ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Chemistry
  • American Association for the Advancement of Science (AAAS)  (342)
  • Ambleside, UK  (27)
  • Tehran, Iran  (12)
  • Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
  • 1
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5238 | 1256 | 2011-09-29 15:13:42 | 5238 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: This report presents five batches of data which have been despatched to the Joint Research Centre, Ispra. The data as been allocated to various ECDIN (Environmental Chemicals Data and Information Network) files. The data comprises environmental chemicals in the freshwater environment, taking in paricular consideration: aquatic toxicity, bioaccumulation, metabolism and elimination biodegradation.
    Keywords: Chemistry ; Ecology ; Limnology ; Data ; Data processing ; Data collections ; Chemical compounds ; Toxicity ; Bioaccumulation ; Biodegradation ; Metabolism
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 8
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5293 | 1256 | 2011-09-29 15:08:09 | 5293 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: Esthwaite Water is the most productive or eutrophic lake in the English Lake District. Since 1945 its water quality has been determined from weekly or biweekly measurements of temperature, oxygen, plant nutrients and phytoplankton abundance. The lake receives phosphorus from its largely lowland-pasture catchment, sewage effluent from the villages of Hawkshead and Near Sawrey, and from a cage-culture fish farm. From 1986 phosphorus has been removed from the sewage effluent of Hawkshead which was considered to contribute between 47% and 67% of the total phosphorus loading to the lake. At the commencement of phosphorus removal regular measurements of phosphorus in the superficial 0-4 cm layer of lake sediment were made from cores collected at random sites. Since 1986 the mean annual concentration of alkali-extractable sediment phosphorus has decreased by 23%. This change is not significant at the 5% level but nearly so. There has been no marked change in water quality over this period. Summer dominance of blue-green algae which arose in the early 1980s after decline of the previous summer forms, Ceratium spp., has been maintained. Improvement in water quality is unlikely to be achieved at the present phosphorus loading.
    Keywords: Chemistry ; Limnology ; Pollution ; Eutrophication ; Freshwater lakes ; Limnological surveys ; Phosphorus ; Phytoplankton ; Primary production ; Sediment analysis ; Water quality ; England ; Esthwaite Water
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 119-131
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    facet.materialart.
    Unknown
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25179 | 18721 | 2018-09-03 17:23:17 | 25179 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-16
    Description: In this study two species of algae, Sargassum glaucescens and Padina boergeseni that found plenteously in Persian Gulf and Bushehr coast, were collected and hot water extracts of them were lyophilized. F. indicus (11.32±1.20 g), after two weeks adaptation in Shoghab research station were immersed in seawater (39 ppt and 25±1 ○C) containing hot-water extract of each brown algae, S.glaucescens and P.boergeseni, at 100, 300 and 500 mg/l concentration, Survival rate and immunological parameters (total haemocyte count (THC), total plasma protein (TPP), Phagocytic activity, bacterial clearance efficiency and bactericidal activity) were examined. In addition effect of dietary administration of beta 1, 3 1, 6 glucan on prevention of White Spot Disease and immunological parameters of shrimp were investigated. According to results, immersion in seawater containing 300 and 500 mg/l concentration of algal hot-water extract after 2 and 3 hours or oral administration of beta 1,3 1,6 glucan at level of 10 g/kg diet for 14 days significantly enhanced THC, TPP, Phagocytic activity, bacterial clearance efficiency and bactericidal activity. Immersion in seawater containing 100, 300 and 500 mg/l hot-water extract of S.glaucescens after 3 hours, improved the survival rate of WSSV-infected F. indicus.
    Keywords: Biology ; Chemistry ; Iran ; Persian Gulf ; Bushehr Province ; Beta-glucan ; Sargassum ; Padina algae ; WSD ; Fenneropenaeus indicus ; Species ; Algae ; Brown Algae ; S.glaucescens ; P.boergeseni ; Survival rate ; White Spot Disease ; Shrimp
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 57
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    facet.materialart.
    Unknown
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25618 | 18721 | 2018-10-07 16:34:53 | 25618 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-16
    Description: Chitin and chitosan are 2 very important products of biopolymer that enjoy high consumption in industry, but their production sources are very limited. In this study, Artemia urmiana cyst shells were obtained from previously collected and stored ones in Iranian Artemia Research Center. 20 kg of Artemia urmiana cyst shells were sampled, cleaned, separated, dried and transferred to Iranian Artemia Research Center Laboratory to extract their Chitin and chitosan. Their chitin and chitosan initially were extracted using optimized common chemical methods. Their properties were compared to 2 other types of Chitin and chitosan obtained from crab and shrimp manufactured by Vietnam and China, respectively. To determine their quality, elemental analysis device, infrared spectrophotometry, x –ray radiography, determination of viscosity , molecular weight, crystallinity percent, color, de stylization measure, empirical and molecular formulas were made. The results showed that the percentage of chitin obtained from Artemia cyst Shells in Chemical method was 28 ± 3 % by weight and efficiency into chitosan (grade steel relief) in this method was 50± 5%. To optimize the extraction procedure and the removal of proteins of chitin by biological practices that were done by sodium hydroxide in the chemical method, it was replaced by the bacterium Bacillus subtilis. And in the bio- phase of chitosan de steelation fungus Aspergillus niger enzyme was replaced instead of sodium hydroxide at high temperatures. The results showed that chitin and chitosan can be extracted from Artemia cyst shell using biological method and their characteristics included as in chitin 49.6% C, 8.2 % N, 7.5 % H, and 34.5 %O. Also the same levels for chitosan were 44.4 %, 8.9, 7.2 and 39.5 %, respectively. Their other quality characteristics were included chitin average molecular weight 4.9×10^6 Dalton, crystallinity percentage of 36.4, viscosity at 20°C 31 centipoise and its color was gray to brown. In the biologic method, the average molecular weight of chitosan, crystallinity percentage, viscosity at 20°C, were 5.1×105 Dalton, 94.5, and 18 centipoises, respectively. Also, its color was pale brown. Chemical structure of extracted chitin and chitosan from the shell of Artemia urmiana cysts were C_7H_12NO_4 and C_6H_11 NO_4c, respectively. The comparison of chitin and chitosan obtained from each chemical and biological method revealed that replacing biological methods instead of chemical methods is possible in achieving these products at suitable condition and better quality. This can eliminate the use of chemicals damaging the environment such as sodium hydroxide and decrease environmental pollution.
    Keywords: Biology ; Chemistry ; Iran ; Artemia urmiana cyst shell ; Chitin ; Chitosan ; Chemical ; Biological methods ; Crab shell ; Shrimp shell ; Biotechnology
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 82
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    facet.materialart.
    Unknown
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25642 | 18721 | 2018-10-14 02:40:17 | 25642 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-16
    Description: Padina boergesenii is one of the most abundant brown algae distributed in the north of Persian Gulf and Oman Sea. In this study after sampling and preparation of Padina boergesenii by Chroform-Etanol (3-1) solvent and by Methanol has been extract. Separation and purification of the compounds was carried out using thin layer, general and inverse column chromatography, Cephadex and high-performance liquid chromatography (HPLC). Structural elucidation of the constituents was based on the data obtained from H-NMR, 13C-NMR, HSQC, HMBC, DEPT and Cephadex LH-20. The steroids compounds separated from above alga were identified as 22dehydrocholesterol (1), cholesterol (2), fucosterol (3), β-sitosterol (4), stigmasterol (5), ostreasterol (6) and two epimer of hyroxyestrol(7), based on their spectral data and from comparison with those previously reported in the literature.
    Keywords: Biology ; Chemistry ; Iran ; Oman Sea ; Persian Gulf ; Brown Algae ; Padina boergesenii ; Steroids compounds ; Extraction ; Purification ; Identification ; Amount verification ; Sargassum glaucescens ; Algae ; Abundant ; Sampling ; Chromatography ; Cephadex ; Dehydrocholesterol ; Cholesterol ; Fucosterol ; β-sitosterol ; Stigmasterol ; Ostreasterol
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 42
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    facet.materialart.
    Unknown
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25792 | 18721 | 2018-10-13 08:54:26 | 25792 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-16
    Description: Cheshmehkileh River and adjacent mountainous streams, play a strategic role as a historical axis for anthropogenic civilization, human welfare also habitat and migration pathway of commercial – biologic valuable fishes e.g. Caspian trout, Caspian kuttum, members of Cyprinidae family in south Caspian Sea drainage. Treats such as overfishing of Caspian trout and Red spotted trout stocks in mountainous headwaters, barriers construction and manipulations those are out of river carrying capacity developed by human activities, affected normal function of river as well. Sand mining big factories establishment next to the river, legal and illegal trade of river sediments, direct entry of Tonekabon landfill leakage into the river, development of Rainbow trout farms since 3 decades and huge effluents into the river containing dead fish and types of solids, escapement of cultured Rainbow trouts into the river, … are major minimum factors which needs basic information for integrating inclusively drainage management system. Cheshmehkileh River contains Headwaters of Dohezar (Daryasar & Nusha), Sehezar and Valamroud rivers during 13 monthly sampling phases between September 2009 and October 2010 based on macrozoobenthoses investigations by EPT, EPT/C EPA protocols, measurements of nominated physic-chemical and microbiologic parameters. Probability of Rainbow trouts escapement and invasion, existence, nutrition in Cheshmehkileh environment indeed investigated. Data analysis explained significant differences (P〈0.05) between groups of measured parameters in different sampling stations. Dendogram of clustered analysis based on consolidation of major biologic/ physic-chemical and microbiologic parameters, separated stations No. 1, 3, 2, 4 in one group and remained classified in different groups. Station 8 and 9 similarly separated which expressed general similarities according to Sehezar river environment which were differs in comparison with other stations. Station 11 separated according to its natural quality of water and environment. Similarities between station 10 to Sehezar river stations 8 and 9 expressed general influence of Sehezar River more than Dohezar River in Cheshmehkileh condition especially in station No. 10. High scores of EPT and EPT/C indices in upstream stations 1, 3 and 8 also low score of indices in stations 7, 13 and 6 expressed levels of environment quality between these groups of stations. Maximum average biomass of macroinvertebrates belongs to Trichoptera order in Cheshmehkileh River. Significant decrease of biomass in stations 11, 12 and 13 in comparison with other stations stated environment degradation in mentioned stations relevant to excessive sand mining as well. Pollution resistant groups of invertebrates significantly increased in downstreams against upstream stations. Also disappearing of Plecoptera order in station No. 7, 9, 10 and 13 stated low quality of environment in comparison with upstream stations. Confirmation of effects quality and quantity for point and non-point sources of imported pollutants require specific management considerations in order to present exploitations, pollutants control and emergencies for river monitoring in forthcoming years.
    Keywords: Aquaculture ; Management ; Iran ; Tonekabon ; Cheshmehkileh ; River ; Pollution ; Aquaculture ; EPTC ; Assessment ; Macroinvertebrates ; Chemistry ; Microbiology
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 138
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2021-07-16
    Description: In this study, first, the influence of three precooking methods (steaming, oven-baking and microwave-cooking) on the contents of mineral elements-copper, zinc, iron, calcium and sodium-of silver carp (Hypophthalmichthys molitrix) was evaluated. Determination results of evaluated elements in raw fish and cooked samples were in range 3.05 to 4.19 for copper, 71.45 to 82.85 for zinc, 32.18 to 40.70 for iron, 425.6 to 529.46 and 315.5 to 534.76 for calcium. Results showed different precooking treatments had no significant effects on the amounts of mineral elements such as copper, zinc, calcium and sodium. The Iron content in the samples subjected to microwave cooking increased. With doing multivariate analysis, on comparing the raw and precooked fillets, steam cooking found to be the best precooking method on retain mineral elements. After choosing the best precooking method, for evaluating the influence of different filling media including sunflower oil, soybean oil, olive oil and brine, on the quality of canned silver carp, amounts of mineral elements(copper, zinc, iron, calcium and sodium) and microbial indices(total counts, thermopile count and clostridium) and sensory indices (color, smell, taste and texture) was surveyed. Assessments of microbial indices showed no microbial activity in canned products. After canning amounts of sodium increased in all the treatments. Except for iron, using soybean oil had no significant effect on the contents of other elements. The highest levels of iron and copper were observed in olive oil canned samples sterilized at 130°C. Sensory evaluating showed, kind of filling media had no significant effects on sensory indices such as taste, smell and color of canned samples. The texture of soybean oil canned samples and the quality defects of olive oil and brine canned samples had better condition than other treatments. In the last step, canned silver carp were proceed under three different temperatures (115°C, 120°C and 130°C) with equal lethality value (Fo=7min), then sensory indices and amount of mineral elements were compared. Results showed, the contents of iron, copper, sodium and calcium were changed in soybean oil canned sample. The amounts of copper and sodium in sunflower oil canned sample subjected to different heating regimes showed significant variation. The highest amount of copper was observed in the canned samples subjected to 130°C heating regime. Results showed contents of iron and copper of olive oil canned sample subjected to 120°C and 130°C heating regimes were higher than sample subjected to 115°C heating regime, while the zinc and calcium contents had no variation. In brine canned samples the highest amounts of copper and iron was obtained after sterilization in 120°C. Results of sensory evaluation showed different heating regimes had no significant effects on the indices of taste, smell, and color of products. Doing 130°C heating regime in brine canned samples led to obtain the better tenacity of texture. While this heating regime caused to increase the quality defects of soybean oil canned samples as a result of existence of hard parts of bone.
    Keywords: Chemistry ; Fisheries ; Iran ; Precooking ; Filling media ; Heating regime ; Sterilization ; Silver carp ; Mineral elements ; Hypopthalmichthys molitrix ; Samples ; Sunflower oil ; Soybean oil ; Silver Carp
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 109
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    facet.materialart.
    Unknown
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25118 | 18721 | 2018-08-22 02:17:23 | 25118 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-16
    Description: Studies show that thyroxine can play an important role in regulating growth and other physiology activities. Since the direct role of thyroxine in growth metamorphose larval of bony fishes hasn't been proved yet, during the experiment accomplished in Shahid Ansari and Jajrood station, the hormones function in the survival of development of silver carp, grass carp and rainbow trout were studied. In this study accomplished of thyroxine baths with 0.1, 0.5 and 1 ppm (with 3 repeat). The other phase, thyroxine injected to females grass carp, silver carp, rainbow trout and barbell of Caspian Sea with different doses (1, 10 and 100 g/g B.W.). Tehn survival of development of embryo and larval and precent of fertilization were studied. Also, the percent of mortality were compared in two phases in stages of development. Results show that: 1) Trout: a) Phase of thyroxine bath: The number of hatching eggs and survival of larval in 0.5 ppm were increased to other treatment. b) Phase of hormone injection: The survival of larval in treatment of 10 g/g was 8.58% that was meaningful difference to other treatment (P〈0.05). 2) Silver carp: a) Phase of thyroxine bath: The number of hatching eggs and survival of larval in 0.5 ppm were (20%) increased to other treatment (P〈0.5). b) Phase of hormone injection: The survival of larval in treatment of 10 g/g was meaningful difference to other treatment (P〈0.05). 3) Grass carp: a) Phase of thyroxine bath: The number of hatching eggs and survival of larval in 0.5 ppm were 39% increased to other treatment. b) Phase of hormone injection: The survival of larval in treatment of 1 g/g was meaningful difference to other treatment (P〈0.05). 4) Barbel of Caspian Sea: Development stages wasn't determined in this fish. Number of eggs degenerated, number of eggs were the first development stages and growth of numbers increased on ovary.
    Keywords: Biology ; Chemistry ; Iran ; Caspian Sea ; Thyroxine ; Female ; Survival ; Growth ; Egg ; Larval ; Grass Carp ; Silver Carp ; Thyroxine (T4)
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 39
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    facet.materialart.
    Unknown
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25713 | 18721 | 2018-10-10 10:11:15 | 25713 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-16
    Description: Chitin nanofibers are prepared from the exoskeletons of shrimp by a simple mechanical treatment after a series of purification steps. The nanofibers have fine nanofibers networks with a uniform width of approximately 10 nm. Grinders and highpressure water jet systems are effective for disintegrating chitin into nanofibers. Acidic conditions are the key factor to facilitate mechanical fibrillation. Ultrafine fibers were successfully fabricated chitosan and fish skinextracted gelatin via electrospinning (ES). Important ES parameters, such as concentration of aqueous acid and fish gelatin solutions, and electric field intensity were examined to investigate the effects on the morphology of the gelatin nanofibers. Due to the poor mechanical properties of the fish gelatin membranes, composite nanofibers made of fish gelatin and poly(L-lactide)(PLLA) were produced with a novel solution. The introduction of PLLA remarkably improved the mechanical properties of the gelatin membranes. With a combination of good biocompatibility and mechanical properties, fish gelatin/PLGA blending non-woven mats are considered to be very promising in fish fillet coating application.. in this study, we fabricated a novel nanofibers composed of fish collagen (FC) and polycaprolactone (PCL) blends by using the electrospinning method. Nanofibers were characterized using a scanning electron microscope (SEM), and it was revealed that the diameter of nanofibers decreases as FC content was increased in the FC/PCL composite nanofibers. Several modifications to the chitin NF surface are achieved, including acetylation, deacetylation and maleylation. The results of this study revealed that: 1–It is possible to produce Nanofibers from chitosan and fish gelatin. 2– Covering and coating of processed fish by nanofibers are applicable and increasing the possibility of shell life for the processed fish. 3– Nanofibers which have been produced from chitosan and fish gelation not only is environmentally friendly but also it will be eatable while has been covered for fish fillets. biocompatible chitosan and gelatin made from fish, fresh fish fillets do not have the ability to cover and packaging, but is edible and used.
    Keywords: Biology ; Chemistry ; Fisheries ; Iran ; Chitin ; Chitosan ; Nanofiber ; Chemical modification ; Fish ; Aquatic ; Maintenance
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 66
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2021-07-16
    Description: This study was conducted to determine phosphorous and nitrogen species at the surface sediment in the southern Caspian Sea (Mazandaran Coast, Kelarabad). Surface sediments samples were collected at three stations from autumn of 2011 to winter of 2012. All samples were prepared by digesting and extracting processes and then phosphorous and nitrogen species concentrations determined using spectroscopy instrument. Results of this study showed that annual mean of Loosely-P, Fe-P, Al-P, Bioava.-P, Ca-P, TIP, Rese.-P and TP was obtained as 5.06±0.33, 55.11±2.52, 42.38±3.74, 102.52±5.68, 172.91±7.12, 275±9.12, 333.30±28.52 and 608±52 µg/g.dw, respectively. The results also showed that inorganic phophorous was less than organic phophorous during different seasons, however, mean percentage of residue-P containing organic compounds and non-degradable compounds was more than 50 percent. Percentage of Ca-P was higher than 60, whereas Bioava.-P was less than 40 percent. In addition, Fe-P and Loosely-P attained the maximum and minimum values, respectively, among the bioavailable phophorous. The order of different forms of phosphorous were recorded as Org-P〉Ca-P〉FeP〉Al-P〉Loosely-P. Annual mean of NH4/N, NO2/N, NO3/N, TIN, TON and TN were observed as 4.23±0.50, 0.06±0.01, 0.74±0.12, 5.02±0.53, 2.48±0.63 and 7.53±0.51 µg/g.dw, respectively. Annual percentage of TIN was two folds than TON and concentration of NH4/N was also four times than NO3/N. As a conclusion, the results revealed that main causes of Bioava.-P adsorption and desorption were temperature, Eh and pH. Also, the form of NH4+/N was of a high percentage because of anaerobic condition in the sediments. According to the high ratios of nitrogen/phosphorous of sediments to nitrogen and phosphorous of bottom water, it finds that released of those from the sediments to water will be happened with high rates. Therefore, it is expected that the establishment of fish farming cages should be carried out with more precautionary approaches which not leads to increased algae bloom.
    Keywords: Biology ; Chemistry ; Ecology ; Iran ; Caspian Sea ; Kelarabad ; Mazandaran coast ; Phophorous ; Nitrogen ; Surface sediment ; Determination ; Breeding
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 42
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    facet.materialart.
    Unknown
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25772 | 18721 | 2018-10-13 08:08:05 | 25772 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-16
    Description: Seaweed belonged to baseborn marine plants with cell wall containing of valued polysaccharides such as Agar, Alginate, Limen sulfate and Carmine, used as food additives and in different industries. Base on previous studies, more than 1000 MT. of Sargassum seaweed withdraw from Oman Sea in Sistan and Baluchistan coastal line which can be collect, dried and powdered for using as supplement in shrimp feed. In this project, Sargassum ilicifolium collected from 6 coastal areas, rinsed, dried, powdered and measured the nutritional values in laboratory for surveying statistically. According to the high nutritional value of Tis coastal seaweed, this variety seaweed powder, replaced with protein resources (fish meal and Soy and Wheat) of white-leg shrimp feed which was formulated by Havorash feed factory of Boshehr in four treatments (A: as control without any replacement) B: with 5%, C: 10 % and D: 15% seaweed replacement, each with three replicates in order to obtain isonitrogenus 33% CP., and iso-caloric (13% fat and 15% carbohydrate) feed using winfeed software. The weighed milled ingredients were carefully mixed using a laboratory food mixer. The mixtures were primed with 30% hot water to yield a suitable pulp. Wet diets were made into 2 mm pellet size and dried at 40 °C in a drying cabinet and maintained in standard condition which was used for water stability and absorption capacity test of the pellets in sea water, statistically one way- ANOVA. The Tis coastal seaweed with 9.8% CP, 2% lipid and 23% carbohydrate had higher nutritional value compared to the other gathered seaweed. Also amino acid and fatty acid profiles, vitamins and minerals were measured in all seaweed samples each, with three replications. As result, for using Sargassum ilicifolium as vitamins and mineral premixes in white- leg shrimp feed, Zinc, Cobalt and Phenylalanine with dose of 1.1, 06.0 and 4.0 ml. 100% dried seaweed must be added respectively. The water stability of D feed treatment in seawater (98%) and C (97%) had statistical differences with A and B (95% stability) (P〈0.05). Water absorption capacity of feeds after one hour immersion in seawater showed significance difference between D (110%) and three others, C(100%), B(85% and control(80%) (P〈0.05). As final aim of this project, enriched product of this seaweed as minerals and vitamins supplements were handsel joinery in the Second Medicine Plant Festival, 2016 and registered in recording organization to give the final certificate.
    Keywords: Aquaculture ; Chemistry ; Iran ; Sargassum illicifolium ; Sargassum illicifolium ; Mineral and vitamins supplements ; Natural binder ; Litopenaeus vannamei ; Seaweed ; Vitamin ; White leg shrimp
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 82
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    facet.materialart.
    Unknown
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25580 | 18721 | 2018-10-07 10:35:48 | 25580 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-16
    Description: By-products consist of more than half of the total weight of fish. Most part of these wastes made from connective tissue proteins that provide good potential to produce gelatin. Nowadays, consumers are more health conscious and have responded to the call for a diet that contains low calorie and low fat. This work involved the characterization of a low-fat spread made of fish gelatin as gelling agent, emulsifier and fat replacer. Six treatments with Fish gelatin (FG) to pectin ratio 1:1 and 2:1, with pectin concentration of 1, 2 and 3%, were produced and evaluated for quality changes and storage-life at refrigerated storage. The results showed that prepared emulsions were physically stable and no phase separation observed during 8 wks. The pH of treatments was 4.5 to 4.9. The moisture content of treatments varied from 68.9% for T1 (FG/pectin ratio 1:1) to 65.4% for T6 (FG/pectin ratio 6:3). The Max. lipid of samples was measured 28.4%. Max. and min. protein of samples were 3.8% for T6 and 1.6% for T2 (FG/pectin ratio 2:1), respectively. No significant differences (p≥0.05) were observed between ash content of all treatments and control (commercial margarin). The acidity of treatments increased during storage and were significantly different from production day (p≤0.05). Peroxide value (PV) of treatments increased significantly at refrigerated storage. No significant differences were observed between PV of treatments during different wks of sampling. The results of texture profile analysis showed that firmness, compressibility and adhesiveness properties were significantly increase with higher substitution of FG with pectin. Color, Aroma, Taste and texture properties of prepared samples were found to significantly lower than control, according to sensory evaluation. Significant increases were observed in mold/yeast and psychrophilic count of treatments during storage. The macroscopic growth of molds was observed on all samples in 8th wks. No coliform growth was observed in all treatments at any time. Results suggest that low-fat spread properties were significantly influenced by different ratios of fish gelatin and pectin incorporated. It seems that these results can provide new opportunities to develop market with introducing novel products to response consumer demands. Some quality defects observed in this study can be improved by using suitable machinery at industrial scale.
    Keywords: Biology ; Chemistry ; Iran ; Fish gelatin ; Low-fat spread ; Fish wastes ; Quality characterictics ; Texture profile ; Shelf-life ; Refrigerated temperature ; Cultured Carp ; Diet ; Lipid
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 74
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5157 | 3949 | 2011-09-29 15:19:58 | 5157 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: The area studied was the River Frome system below Dorchester. The main river has its origins mainly in chalk springs, although some of its tributaries have surface run-off from farm lands and heath-lands. Thus the chemistry of the river is affected by changes in land practice and differences in the geology of the catchment area. Regular chemical analysis of chalk waters started at the River Laboratory in 1964, Regular weekly analyses have been carried out since 1965 at Bere Stream (a small chalk stream) and the River Frome (a large chalk stream); also single samples have been analysed to provide preliminary information. In 1970-71 an attempt was made to discover the contribution each main source made to the flow and chemical composition of the River Frome. Results of these investigations are presented in the paper.
    Keywords: Chemistry ; Environment ; Chemical analysis ; Chemical composition ; Rivers ; Stream flow ; Annual report ; England ; Dorset
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5171 | 3949 | 2011-09-29 15:18:48 | 5171 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: An explanation of the basic premises of the subject and its terminology is given. The article then outlines aspects of research on the organic material found in lacustrine sediments, and the analytical methods involved.
    Keywords: Chemistry ; Earth Sciences ; Diagenesis ; Freshwater lakes ; Geochemistry ; Lipids ; Sediment analysis ; Annual report
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 45-56
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5225 | 1256 | 2011-09-29 15:12:36 | 5225 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: The overall goal of the joint research project is to relate the chemical reactions involved in the formation of organo-aluminium complexes under acid conditions to their toxic effects on the physiology of aquatic organisms. Finally, this research is intended to predict toxic effects arising from acidity and aluminium under varying environmental conditions. This interim report examines the chemical modelling of ion-binding by humic substances where a computer model has been developed and is being tested using field data, and conditions required for the precipitation of aluminium in surface waters.
    Keywords: Chemistry ; Limnology ; Pollution ; Modelling ; Models ; Humic acids ; Surface water ; Aluminium compounds ; Aluminium ; Ions ; Toxicity ; England ; Duddon River
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 26
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5239 | 3949 | 2011-09-29 15:13:47 | 5239 | Freshwater Biological Association
    Publication Date: 2021-06-24
    Description: This review discusses the processes involved in the decomposition of organic carbon derived initially from structural components of algae and other primary producers. It describes how groups of bacteria interact in time and space in a eutrophic lake. The relative importance of anaerobic and aerobic processes are discussed. The bulk of decomposition occurs within the sediment. The role of bacteria in the nitrogen cycle and the iron cycle, and in sulphate reduction and methanogenesis as the terminal metabolism of organic carbon are described.
    Keywords: Biology ; Chemistry ; Anaerobic bacteria ; Bacteria ; Biodegradation ; Carbon cycle ; Eutrophic lakes ; Fresh water ; Geochemical cycle ; Iron ; Manganese ; Nitrates ; Nitrogen cycle ; Organic carbon ; Oxygen consumption ; Partical size ; Sedimentation ; Sulphates ; Sulphur ; Annual report
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 31-44
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5247 | 3949 | 2011-09-29 15:08:19 | 5247 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: The dace, Leuciscus leuciscus (L.) is an important cyprinid in terms of population biomass in chalk streams of southern England. Dace recruitment has been shown to vary widely from year to year and it is thought that this variation is largely as a result of the influence of abiotic factors, chiefly water temperature. From 1968 to 1981 there was a thirteen-fold difference in the year class structure index between the minimum index (0.25 in 1972) and the maximum (3.21 in 1976). The problems of such variation, especially those that could ensue from a succession of poor year-classes, are offset by the spread of reproductive effort by each female over several years.
    Keywords: Biology ; Chemistry ; Fisheries ; Abiotic factors ; Age composition ; Annual variations ; Climate ; Fecundity ; Fish eggs ; Fish larvae ; Freshwater fish ; Life history ; Mortality ; Population dynamics ; Predation ; Recruitment ; Sexual reproduction ; Survivial ; Water temperature ; Cyprinidae ; Leuciscus leuciscus ; England ; Dorset ; Chalk streams ; Annual report
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 83-96
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5257 | 1256 | 2011-09-29 15:09:23 | 5257 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: Phosalone is a non systematic, wide spectrum organophosphate pesticide which was discovered in 1961 in the laboratories of the Societe des Usines Chimique Rhone-Poulenc in France. It has been approved for commercial use since 1964 in France, in Australia since 1966, in the United Kingdom in 1967 and in many other countries including Japan, Egypt, USSR and the USA. This study provides a full literature review on all aspects of phosalone including its physical, biological and chemical characteristics, and analytical methods of analysis with particular reference to soils/sediments. Furthermore, it aims to develop a method for the determintion of phosalone in aquatic sediments and to determine the adsorption of phosalone onto kaolinite.
    Keywords: Chemistry ; Limnology ; Pollution ; Insecticides ; Metabolism ; Toxicity ; Biodegradation ; Adsorption
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 54
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5278 | 1256 | 2011-09-29 15:11:09 | 5278 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: A literature survey was carried out into the effects of petroleum hydrocarbons in freshwater, from the toxicity, biodegradability and concentration aspects. It was supplemented by a selective search on hydrocarbons in the marine environment for comparison. The aim was to determine the major inputs of these hydrocarbons, their accumulation, effects and fate in freshwaters. The search was confined to the period 1965-1978. The bibliography contains 390 references, divided by subject.
    Keywords: Chemistry ; Limnology ; Pollution ; literature reviews ; petroleum ; toxicity ; biodegradation
    Repository Name: AquaDocs
    Type: book , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 52
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5349 | 1256 | 2011-05-13 11:55:43 | 5349 | Freshwater Biological Association
    Publication Date: 2021-07-10
    Description: This dataset provides raw data of chemical analyses made during studies on seasonal variations of some major ions in the stream water of the River Duddon in Cumbria. Measurements of sodium, calcium, potassium, magnesium and chloride ions and pH were taken at 5 stations in the River Duddon between January 1970 and August 1974.
    Description: This data was used in the publication: Carrick, T.R. & Sutcliffe, D.W.: Concentrations of Major Ions in Streams on Catchments of the River Duddon (1971-1974) and Windermere (1975-1978), English Lake District. Freshwater Biological Association, Ambleside, UK, 1983 (FBA Occasional Publications 22)
    Keywords: Chemistry ; Limnology ; Calcium ; chlorides ; fresh water ; ions ; magnesium ; potassium ; seasonal variations ; sodium ; water analysis ; dataset
    Repository Name: AquaDocs
    Type: other
    Format: text/html
    Format: application/vnd.ms-excel
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5351 | 1256 | 2011-05-13 11:55:21 | 5351 | Freshwater Biological Association
    Publication Date: 2021-07-10
    Description: This dataset provides raw data of chemical analyses made during studies on seasonal variations of some major ions in the stream water of the catchment of Lake Windermere in Cumbria. Measurements of sodium, calcium, potassium, magnesium, chloride ions and pH were taken at 37 stations in the catchment between 1975 and 1978.
    Description: This data was used in the publication: Carrick, T.R. & Sutcliffe, D.W.: Concentrations of major ions in streams on catchments of the River Duddon (1971-1974) and Windermere (1975-1978), English Lake District. Freshwater Biological Association, Ambleside, UK, 1983 (FBA Occasional Publications 22)
    Keywords: Chemistry ; Limnology ; Calcium ; chlorides ; fresh water ; ions ; magnesium ; potassium ; seasonal variations ; sodium ; water analysis ; England ; Lake Windermere ; dataset
    Repository Name: AquaDocs
    Type: other
    Format: text/html
    Format: application/vnd.ms-excel
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5354 | 1256 | 2011-09-16 12:01:28 | 5354 | Freshwater Biological Association
    Publication Date: 2021-07-10
    Description: This dataset provides raw data of chemical analyses made during studies on seasonal variations of 182 tarns in the English Lake District, Cumbria. Measurements of sodium, calcium, potassium, magnesium, pH, chloride ions, alkalinity, sulphite, strong acids and nitrate were taken between 1953 and 1978.
    Description: This data was used in the publication: Carrick, T.R. & Sutcliffe, D.W.: Concentrations of major ions in lakes and tarns on the English Lake District (1953-1978). Freshwater Biological Association, Ambleside, UK, 1982 (FBA Occasional Publications 16)
    Keywords: Chemistry ; Limnology ; Calcium ; chlorides ; fresh water ; ions ; magnesium ; potassium ; seasonal variations ; sodium ; water analysis ; alkalinity ; England ; Lake District ; dataset
    Repository Name: AquaDocs
    Type: other
    Format: application/vnd.ms-excel
    Format: application/vnd.ms-excel
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5352 | 1256 | 2012-07-04 19:32:47 | 5352 | Freshwater Biological Association
    Publication Date: 2021-07-10
    Description: This dataset provides raw data of chemical analyses made during studies on seasonal variations of treated sewage effluent from Grasmere Treatment Unit in Cumbria. Measurements of sodium, calcium, potassium, magnesium and chloride ions were taken between 1974 and 1976.
    Description: This data was used in the publication: Carrick, T.R. & Sutcliffe, D.W.: Concentrations of major ions in streams on catchments of the River Duddon (1971-1974) and Windermere (1975-1978), English Lake District. Freshwater Biological Association, Ambleside, UK, 1983 (FBA Occasional Publications 22)
    Keywords: Chemistry ; Limnology ; Calcium ; chlorides ; fresh water ; ions ; magnesium ; potassium ; seasonal variations ; sodium ; water analysis ; England ; Grasmere ; dataset
    Repository Name: AquaDocs
    Type: other
    Format: application/vnd.ms-excel
    Format: application/vnd.ms-excel
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5350 | 1256 | 2011-05-13 11:56:03 | 5350 | Freshwater Biological Association
    Publication Date: 2021-07-10
    Description: This dataset provides raw data of chemical analyses made during studies on seasonal variations of some major ions in the stream water of the upper basin of the River Duddon in Cumbria. Measurements of sodium, calcium, potassium, magnesium and chloride ions and pH were taken at 26 stations in the River Duddon basin between 1972 and 1974.
    Description: This data was used in the publication: Carrick, T.R. & Sutcliffe, D.W.: Concentrations of Major Ions in Streams on Catchments of the River Duddon (1971-1974) and Windermere (1975-1978), English Lake District. Freshwater Biological Association, Ambleside, UK, 1983 (FBA Occasional Publications 22)
    Keywords: Chemistry ; Limnology ; Calcium ; chlorides ; fresh water ; ions ; magnesium ; potassium ; seasonal variations ; sodium ; water analysis ; England ; River Duddon ; dataset
    Repository Name: AquaDocs
    Type: other
    Format: text/html
    Format: application/vnd.ms-excel
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5353 | 1256 | 2012-07-04 19:33:33 | 5353 | Freshwater Biological Association
    Publication Date: 2021-07-10
    Description: This dataset provides raw data of chemical analyses made during studies on seasonal variations of 25 frequently sampled tarns in Cumbria. Measurements of sodium, calcium, potassium, magnesium, pH, chloride ions, alkalinity, sulphite, strong acids and nitrate were taken between 1954 and 1956 and between 1974-1976.
    Description: This data was used in the publication: Carrick, T.R. & Sutcliffe, D.W.: Concentrations of major ions in streams on catchments of the River Duddon (1971-1974) and Windermere (1975-1978), English Lake District. Freshwater Biological Association, Ambleside, UK, 1983 (FBA Occasional Publications 22)
    Keywords: Chemistry ; Limnology ; Calcium ; chlorides ; fresh water ; ions ; magnesium ; potassium ; seasonal variations ; sodium ; water analysis ; alkalinity ; England ; Lake District ; dataset
    Repository Name: AquaDocs
    Type: other
    Format: application/vnd.ms-excel
    Format: application/vnd.ms-excel
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5111 | 3949 | 2011-09-29 15:23:22 | 5111 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: An article discussing changes observed in phytoplankton of the Lake District. An overview is given of previous phytoplankton studies undertaken in the area, detailing some changes found in various waterbodies. Water quality changes in Lake Windermere are mentioned, including the gradual increase of dissolved organic matter (DOM), believed to be caused by the increase of sewage to the lake. The lakes in the Alps are given as an example of a similar anthropogenic pollution scenario. The treatment of a Lake District tarn with bone meal is described. The article goes on to discuss the composition of plankton throughout the year under a variety of climatic conditions. A figure shows seasonal variation in the consistuents of phytoplankton in Windermere (north basin).
    Keywords: Biology ; Chemistry ; Limnology ; Phytoplankton ; Limnology ; Dissolved organic matter ; Seasonal variations ; Sewage ; Water quality ; Annual reports ; England ; Lake District
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 42-45
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5107 | 3949 | 2011-09-29 15:23:50 | 5107 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: A progress report on research undertaken on the chemical budget of a lake, outlining the importance of nitrogen and phosphorus in governing the production of life in freshwater. The report uses the Rivers Brathay and Leven, which flow into Windermere, as examples. The report also refers to the Rivers Rothay, Troutbeck and Cunsey. A table is including which shows the monthly average nitrate content (mg per litre) of the River Brathey and River Leven for 1937 into 1938. The report also includes a figure showing Windermere lake levels, discharge and rainfall during 1937. It also briefly considers possible anthropogenic influences on water quality.
    Keywords: Chemistry ; Ecology ; Limnology ; Phosphorus ; Organic compounds ; Sewage ; Diatoms ; Algae ; Sediment chemistry ; Seasonal variations ; Annual reports ; Nitrates ; River discharge ; England
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 38-42
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5114 | 3949 | 2011-09-29 15:21:32 | 5114 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: An article looking at the numerical distribution of bacteria in lakes, the types most commonly present and the nitrogen-cycle, in Lake Windermere. The methodology is explained, including the sampling frequency and depths, and bacteria culturing techniques. Water bodies other than Lake Windermere were also sampled and these are detailed, including a water reservoir. A summary of the work into horizontal of bacteria is given, including a table showing the number of bacteria per millilitre at different distances from inflow into Windermere. A summary of the work into vertical distribution is also given, including two figures, one showing seasonal variation during 1938-9 in numbers of bacteria at different depths in Winderemere, and the other showing the relationship between the numbers of bacteria at 10 metres depth in Windermere and the rainfull during the previous 7 days. A summary of the types of bacteria found, as well as work on the nitrogen cycle in Esthwaite Water, Lake Windermere and Blelham Tarn are given.
    Keywords: Biology ; Chemistry ; Limnology ; Nitrogen cycle ; Bacteria ; Freshwater ecology ; Limnology ; Seasonal variations ; Water column ; Water reservoirs ; Annual reports ; England ; Lake District
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 51-57
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5112 | 3949 | 2011-09-29 15:23:20 | 5112 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: An article reviewing the work undertaken looking at the seasonal variation of chemical conditions in water at various depths in lakes. The laboratory tests undertaken for the research is outlined, as well as details of the sampling locations and the staff involved with the work. One figure shows the seasonal variation in the amounts of dissolved substances in the surface water of Windermere during 1936. Another figure shows seasonal varation inthe dry weight of phyto- and zooplankton in Windermere. Seasonal changes are discussed further and a table is included showing chemical conditions in winter and summer for Windermere.
    Keywords: Biology ; Chemistry ; Limnology ; Limnology ; Chemistry ; Seasonal variations ; Diatoms ; Phytoplankton ; Zooplankton ; Water column ; Surface water ; Annual reports ; England ; Lake District
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 46-51
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5122 | 3949 | 2011-09-29 15:22:47 | 5122 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: An article reviewing the methods of biological surveillance of chalk-streams developed and commonly used at that time, with a focus on their application to the River Frome catchment in Dorset. In evaluating the surveillance methods, the author looks at sampling methods (including cores and kick-sampling), the level of identification of macroinvertebrates, and temporal and spatial variations. Responses of indices to organic pollution are also discussed. A number of accompanying figures are also included.
    Keywords: Biology ; Chemistry ; Ecology ; Environment ; Chalk ; Water management ; Cores ; Aquatic communities ; Freshwater ecology ; Invertebrate larvae ; Biological surveys ; Temporal variations ; Spatial variations ; Annual reports ; England
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 81-92
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5123 | 3949 | 2011-09-29 15:22:51 | 5123 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: A review article detailing the background, development and functionality of the Windermere Profiler, a multi parameter environmental monitoring instrument for use in lakes, reservoirs and rivers. The article explains the requirement for regular data collection by the Freshwater Biological Association at Windermere. The article covers the requirements of a profiling instrument, the design considerations, the electronic circuitry, the computer program, the operation of the computer software, the profiler in use and further developments to the design. A number of figures and images accompany the article.
    Keywords: Chemistry ; Environment ; Limnology ; Profilers ; Inland water environment ; Water reservoirs ; Lakes ; Rivers ; Temperature data ; Electrical conductivity ; Dissolved oxygen ; Depth measurement ; Light attenuation ; Annual reports ; England ; Lake District
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 93-106
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5117 | 3949 | 2011-09-29 15:22:21 | 5117 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: An article discussing the factors affecting the rate of growth of brown trout, detailing the research udnertaken at Wray Castle, designed to clarify the influencing factors in different waters and investigate what would be required to increase their size. The article considers factors such as alkalinity, total hardness, the presence of coarse fish in the waterbodies and competition for food. Previous work undertaken on brown trout in Ireland by other authors is reviewed. A figure showing average growth rate of brown trout in five lakes, as determined from their scales (Lough Derg, Windermere, Loch Leven, Ullswater, Haweswater).
    Keywords: Biology ; Chemistry ; Limnology ; Coarse fish ; pH effects ; Water hardness ; Food availability ; Limnology ; England ; Lake District
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 66-71
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5189 | 3949 | 2011-09-29 15:16:49 | 5189 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: There is no evidence of an increase in the acidity (lower pH or alkalinity) of water-bodies in the Lake District over the last 50 years. Brown trout occur in acid streams and upland tarns where pH is 4.5-5.2 throughout the year. Their occurrence in such waters in Britain and Ireland has been known for most of this century and there is no previous evidence of harmful effects on salmonid fisheries, though numbers of fish are naturally low. However, many benthic invertebrates that are common in hill-streams where pH is above 5.7 do not occur in more acid streams. This phenomenon occurs in the headwaters of several western rivers in Cumbria. It is not a recent response to "acid rain". Harmful effects of pH are undoubtedly more pronounced in waters that are poor in other dissolved ions. Low concentrations of sodium, potassium, calcium and chloride are especially important and may limit the distributions of some aquatic animals even where pH is above 5.7. The concentration of sulphate ions is usually relatively high but this is not important to the fauna; concentrations are at least two times higher in productive alkaline water-bodies than they are in unproductive acid waters.
    Keywords: Chemistry ; Ecology ; Limnology ; Acid rain ; Acidification ; Alkalinity ; Freshwater pollution ; pH ; Pollution effects ; Invertebrata ; Salmonidae ; England ; Lake District ; Annual report
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 30-62
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5181 | 3949 | 2011-09-29 15:17:17 | 5181 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: The chemical speciation of both metals and non-metals, the use of polarographic techniques, and application to the study of the chemistry of anoxic waters are considered. In the first part of the paper unfamiliar terminology is explained and then an example of simple lake chemistry is presented to illustrate why the concept of speciation is necessary.
    Keywords: Chemistry ; Limnology ; Chemical speciation ; Anoxic basins ; Annual report
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 53-59
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5195 | 3949 | 2011-09-29 15:15:06 | 5195 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: This review is concerned with the kinetics of calcium carbonate formation and related processes which are important in many hard waters.
    Keywords: Chemistry ; Calcite ; Calcium carbonates ; Chemical precipitation ; Fresh water ; Geochemical cycle ; Annual report
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 75-90
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5193 | 3949 | 2011-09-29 15:15:03 | 5193 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: A study of the geochemical cycling of iron and manganese in a seasonally stratified lake, Esthwaite water is described. This work is based on speculative ideas on environmental redox chemistry of iron which were proposed by C.H. Mortimer in the 1940's. These observations have been verified and some speculations confirmed, along with a new understanding of the manganese cycle, and detailed information on the particulate forms of both iron and manganese. Details on the mechanisms and transformations of iron have also emerged.
    Keywords: Biology ; Chemistry ; Chemical precipitation ; Freshwater lakes ; Iron ; Manganese ; Oxidation ; Redox potential ; Reduction ; Stratification ; England ; Esthwaite Lake ; Annual report
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 91-101
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    facet.materialart.
    Unknown
    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5197 | 3949 | 2011-09-29 15:15:33 | 5197 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: Studies by the Freshwater Biological Association over the last 25 years have supplied data relevant to the levels of acidity in local soils and water before the onset of industrial pollution and current interest in acid rain. This article reviews published analysis from cores of lake sediments, in or near the catchment of the River Duddon. Electron spin resonance spectra of humic acids and iodine values confirm evidence from pollen analysis for a history of progressive acidification of the source material of lake sediments since before 5000 radiocarbon years, in upland catchments of the Lake District. Processes involved included: removal of basic ions from soils by rainfall, the effects of which were intensified by removal by man of deciduous forest; acidification of soils and waters by decomposition products of Calluna and further acidification of waters by Sphagnum species which colonized habitats where drainage became impeded by paludification processes.
    Keywords: Biology ; Chemistry ; Earth Sciences ; Acid rain ; Acidification ; Freshwater lakes ; Lake Basins ; Lake deposits ; pH ; Palnology ; England ; Cumbria ; Annual report
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 28-46
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Publication Date: 2021-05-19
    Description: 0Genetic polymorphism by means of biochemical genetic markers using polyacrylamide gel electrophoresis system in four barbus fish species has been investigated. Species scientific name were Barbus sharpeyi ; Gunther, 1847 , Barbus grypus ; Heckel, 1843, Barbus xanthopterus ; Heckel, 1843 and Barbus esocinus ; Heckel, 1843.Sampling site and location were mainly in the rivers located in Khoozestan province such as Karoon and Karkheh rivers and the Dez dam. Different organs such as blood, muscle, kidney, eye and heart were sampled and analysed for the presence of tf, es, sod and pgm alleles. High polymorphism and presence of different alleles scored, but populations were not in the H-W equilibrium. Considring results, using current and avaiable genetic markers such as microsattelits is recommended for future works.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Chemistry ; Genetics ; Genetics Markers ; Distinguish ; Barbus ; Species ; Barbus sharpeyi ; Barbus xanthopterus ; Barbus esocinus
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 62pp.
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Publication Date: 2021-05-19
    Description: Cheshmehkileh River and adjacent mountainous streams, play a strategic role as a historical axis for anthropogenic civilization, human welfare also habitat and migration pathway of commercial – biologic valuable fishes e.g. Caspian trout, Caspian kuttum, members of Cyprinidae family in south Caspian Sea drainage. Treats such as overfishing of Caspian trout and Red spotted trout stocks in mountainous headwaters, barriers construction and manipulations those are out of river carrying capacity developed by human activities, affected normal function of river as well. Sand mining big factories establishment next to the river, legal and illegal trade of river sediments, direct entry of Tonekabon landfill leakage into the river, development of Rainbow trout farms since 3 decades and huge effluents into the river containing dead fish and types of solids, escapement of cultured Rainbow trouts into the river, … are major minimum factors which needs basic information for integrating inclusively drainage management system. Cheshmehkileh River contains Headwaters of Dohezar (Daryasar & Nusha), Sehezar and Valamroud rivers during 13 monthly sampling phases between September 2009 and October 2010 based on macrozoobenthoses investigations by EPT, EPT/C EPA protocols, measurements of nominated physic-chemical and microbiologic parameters. Probability of Rainbow trouts escapement and invasion, existence, nutrition in Cheshmehkileh environment indeed investigated. Data analysis explained significant differences (P〈0.05) between groups of measured parameters in different sampling stations. Dendogram of clustered analysis based on consolidation of major biologic/ physic-chemical and microbiologic parameters, separated stations No. 1, 3, 2, 4 in one group and remained classified in different groups. Station 8 and 9 similarly separated which expressed general similarities according to Sehezar river environment which were differs in comparison with other stations. Station 11 separated according to its natural quality of water and environment. Similarities between station 10 to Sehezar river stations 8 and 9 expressed general influence of Sehezar River more than Dohezar River in Cheshmehkileh condition especially in station No. 10. High scores of EPT and EPT/C indices in upstream stations 1, 3 and 8 also low score of indices in stations 7, 13 and 6 expressed levels of environment quality between these groups of stations. Maximum average biomass of macroinvertebrates belongs to Trichoptera order in Cheshmehkileh River. Significant decrease of biomass in stations 11, 12 and 13 in comparison with other stations stated environment degradation in mentioned stations relevant to excessive sand mining as well. Pollution resistant groups of invertebrates significantly increased in downstreams against upstream stations. Also disappearing of Plecoptera order in station No. 7, 9, 10 and 13 stated low quality of environment in comparison with upstream stations. Confirmation of effects quality and quantity for point and non-point sources of imported pollutants require specific management considerations in order to present exploitations, pollutants control and emergencies for river monitoring in forthcoming years.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: River ; Pollution ; Aquaculture ; EPTC ; Assessment ; Macroinvertebrates ; Chemistry ; Microbiology
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 138pp.
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    facet.materialart.
    Unknown
    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Publication Date: 2022-05-25
    Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2018
    Description: Many chemical constituents are removed from the ocean by attachment to settling particles, a process referred to as “scavenging.” Radioisotopes of thorium, a highly particle-reactive element, have been used extensively to study scavenging in the ocean. However, this process is complicated by the highly variable chemical composition and concentration of particles in oceanic waters. This thesis focuses on understanding the cycling of thorium as affected by particle concentration and particle composition in the North Atlantic. This objective is addressed using (i) the distributions 228,230,234Th, their radioactive parents, particle composition, and bulk particle concentration, as measured or estimated along the GEOTRACES North Atlantic Transect (GA03) and (ii) a model for the reversible exchange of thorium with particles. Model parameters are either estimated by inversion (chapter 2-4), or prescribed in order to simulate 230Th in a circulation model (chapter 5). The major findings of this thesis follow. In chapters 2 and 3, I find that the rate parameters of the reversible exchange model show systematic variations along GA03. In particular, 𝑘1, the apparent first-order rate "constant" of Th adsorption onto particles, generally presents maxima in the mesopelagic zone and minima below. A positive correlation between 𝑘1 and bulk particle concentration is found, consistent with the notion that the specific rate at which a metal in solution attaches to particles increases with the number of surface sites available for adsorption. In chapter 4, I show that Mn (oxyhydr)oxides and biogenic particles most strongly influence 𝑘1 west of the Mauritanian upwelling, but that biogenic particles dominate 𝑘1 in this region. In chapter 5, I find that dissolved 230Th data are best represented by a model that assumes enhanced values of 𝑘1 near the seafloor. Collectively, my findings suggest that spatial variations in Th radioisotope activities observed in the North Atlantic reflect at least partly variations in the rate at which Th is removed from the water column.
    Description: This work was supported by the US National Science Foundation. Two US NSF grants have supported the research in this thesis (OCE-1232578 and OCE-155644).
    Keywords: Thorium ; Chemistry
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-02-16
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-02-16
    Description: The comment and response concerning the report of oxidation of methane to methanol by water (Reports, 5 May 2017, p. 523) do not fully capture the implications of thermodynamic limitations. A nonisothermal process in which each cycle requires a large temperature swing and permits only substoichiometric methane conversion surely could not be carried out on any practical scale.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Publication Date: 2018-02-16
    Description: Labinger argues that stepwise reaction of methane with water to produce methanol and hydrogen will never be commercially feasible because of its substoichiometric basis with respect to the active site and the requirement of a large temperature swing. This comment is not touching any new ground, beyond describing the thermodynamic feasibility, thermal cycling, and the role of water as discussed previously. Most important, it does not have a solid numerical basis.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-07-27
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Publication Date: 2018-07-27
    Description: Vinyl carbocations have been the subject of extensive experimental and theoretical studies over the past five decades. Despite this long history in chemistry, the utility of vinyl cations in chemical synthesis has been limited, with most reactivity studies focusing on solvolysis reactions or intramolecular processes. Here we report synthetic and mechanistic studies of vinyl cations generated through silylium–weakly coordinating anion catalysis. We find that these reactive intermediates undergo mild intermolecular carbon-carbon bond–forming reactions, including carbon-hydrogen (C–H) insertion into unactivated sp 3 C–H bonds and reductive Friedel-Crafts reactions with arenes. Moreover, we conducted computational studies of these alkane C–H functionalization reactions and discovered that they proceed through nonclassical, ambimodal transition structures. This reaction manifold provides a framework for the catalytic functionalization of hydrocarbons using simple ketone derivatives.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Publication Date: 2018-06-22
    Description: It is commonly assumed that recognition and discrimination of chirality, both in nature and in artificial systems, depend solely on spatial effects. However, recent studies have suggested that charge redistribution in chiral molecules manifests an enantiospecific preference in electron spin orientation. We therefore reasoned that the induced spin polarization may affect enantiorecognition through exchange interactions. Here we show experimentally that the interaction of chiral molecules with a perpendicularly magnetized substrate is enantiospecific. Thus, one enantiomer adsorbs preferentially when the magnetic dipole is pointing up, whereas the other adsorbs faster for the opposite alignment of the magnetization. The interaction is not controlled by the magnetic field per se, but rather by the electron spin orientations, and opens prospects for a distinct approach to enantiomeric separations.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-06-29
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Publication Date: 2018-12-14
    Description: Theory has established the importance of geometric phase (GP) effects in the adiabatic dynamics of molecular systems with a conical intersection connecting the ground- and excited-state potential energy surfaces, but direct observation of their manifestation in chemical reactions remains a major challenge. Here, we report a high-resolution crossed molecular beams study of the H + HD -〉 H 2 + D reaction at a collision energy slightly above the conical intersection. Velocity map ion imaging revealed fast angular oscillations in product quantum state–resolved differential cross sections in the forward scattering direction for H 2 products at specific rovibrational levels. The experimental results agree with adiabatic quantum dynamical calculations only when the GP effect is included.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-17
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-17
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-17
    Description: The chemistry of the carbonyl group is essential to modern organic synthesis. The preparation of substituted, enantioenriched 1,3- or 1,5-dicarbonyls is well developed, as their disconnection naturally follows from the intrinsic polarity of the carbonyl group. By contrast, a general enantioselective access to quaternary stereocenters in acyclic 1,4-dicarbonyl systems remains an unresolved problem, despite the tremendous importance of 2,3-substituted 1,4-dicarbonyl motifs in natural products and drug scaffolds. Here we present a broad enantioselective and stereodivergent strategy to access acyclic, polysubstituted 1,4-dicarbonyls via acid-catalyzed [3,3]-sulfonium rearrangement starting from vinyl sulfoxides and ynamides. The stereochemistry at sulfur governs the absolute sense of chiral induction, whereas the double bond geometry dictates the relative configuration of the final products.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-17
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-17
    Description: With the recent soaring production of natural gas, the use of methane and other light hydrocarbon feedstocks as starting materials in synthetic transformations is becoming increasingly economically attractive, although it remains chemically challenging. We report the development of photocatalytic C–H amination, alkylation, and arylation of methane, ethane, and higher alkanes under visible light irradiation at ambient temperature. High catalytic efficiency (turnover numbers up to 2900 for methane and 9700 for ethane) and selectivity were achieved using abundant, inexpensive cerium salts as photocatalysts. Ligand-to-metal charge transfer excitation generated alkoxy radicals from simple alcohols that in turn acted as hydrogen atom transfer catalysts. The mixed-phase gas/liquid reaction was adapted to continuous flow, enabling the efficient use of gaseous feedstocks in scalable photocatalytic transformations.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-24
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-24
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-31
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-31
    Description: Intrigued by the potential of nanoscale machines, scientists have long attempted to control molecular motion. We monitored the individual 0.7-nanometer steps of a single molecular hopper as it moved in an electric field along a track in a nanopore controlled by a chemical ratchet. The hopper demonstrated characteristics desired in a moving molecule: defined start and end points, processivity, no chemical fuel requirement, directional motion, and external control. The hopper was readily functionalized to carry cargos. For example, a DNA molecule could be ratcheted along the track in either direction, a prerequisite for nanopore sequencing.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Publication Date: 2018-09-21
    Description: Phosphorothioate nucleotides have emerged as powerful pharmacological substitutes of their native phosphodiester analogs with important translational applications in antisense oligonucleotide (ASO) therapeutics and cyclic dinucleotide (CDN) synthesis. Stereocontrolled installation of this chiral motif has long been hampered by the systemic use of phosphorus(III) [P(III)]–based reagent systems as the sole practical means of oligonucleotide assembly. A fundamentally different approach is described herein: the invention of a P(V)-based reagent platform for programmable, traceless, diastereoselective phosphorus-sulfur incorporation. The power of this reagent system is demonstrated through the robust and stereocontrolled synthesis of various nucleotidic architectures, including ASOs and CDNs, via an efficient, inexpensive, and operationally simple protocol.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Publication Date: 2018-09-21
    Description: Here we report an anomalous porous molecular crystal built of C–H···N-bonded double-layered roof-floor components and wall components of a segregatively interdigitated architecture. This complicated porous structure consists of only one type of fully aromatic multijoint molecule carrying three identical dipyridylphenyl wedges. Despite its high symmetry, this molecule accomplishes difficult tasks by using two of its three wedges for roof-floor formation and using its other wedge for wall formation. Although a C–H···N bond is extremely labile, the porous crystal maintains its porosity until thermal breakdown of the C–H···N bonds at 202°C occurs, affording a nonporous polymorph. Though this nonporous crystal survives even at 325°C, it can retrieve the parent porosity under acetonitrile vapor. These findings show how one can translate simplicity into ultrahigh complexity.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-28
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-28
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Publication Date: 2018-09-28
    Description: Some of the simplest and most powerful carbon-carbon bond forming strategies take advantage of readily accessible ubiquitous motifs: carbonyls and olefins. Here we report a fundamentally distinct mode of reactivity between carbonyls and olefins that differs from established acid-catalyzed carbonyl-ene, Prins, and carbonyl-olefin metathesis reaction paths. A range of epsilon, zeta-unsaturated ketones undergo Brønsted acid–catalyzed intramolecular cyclization to provide tetrahydrofluorene products via the formation of two new carbon-carbon bonds. Theoretical calculations and accompanying mechanistic studies suggest that this carbocyclization reaction proceeds through the intermediacy of a transient oxetane formed by oxygen atom transfer. The complex polycyclic frameworks in this product class appear as common substructures in organic materials, bioactive natural products, and recently developed pharmaceuticals.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-28
    Description: Alkene aminoarylation with a single, bifunctional reagent is a concise synthetic strategy. We report a catalytic protocol for the addition of arylsulfonylacetamides across electron-rich alkenes with complete anti-Markovnikov regioselectivity and excellent diastereoselectivity to provide 2,2-diarylethylamines. In this process, single-electron alkene oxidation enables carbon-nitrogen bond formation to provide a key benzylic radical poised for a Smiles-Truce 1,5-aryl shift. This reaction is redox-neutral, exhibits broad functional group compatibility, and occurs at room temperature with loss of sulfur dioxide. As this process is driven by visible light, uses readily available starting materials, and demonstrates convergent synthesis, it is well suited for use in a variety of synthetic endeavors.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-05
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-05
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Publication Date: 2018-10-05
    Description: Photocatalysis based on optically active, "plasmonic" metal nanoparticles has emerged as a promising approach to facilitate light-driven chemical conversions under far milder conditions than thermal catalysis. However, an understanding of the relation between thermal and electronic excitations has been lacking. We report the substantial light-induced reduction of the thermal activation barrier for ammonia decomposition on a plasmonic photocatalyst. We introduce the concept of a light-dependent activation barrier to account for the effect of light illumination on electronic and thermal excitations in a single unified picture. This framework provides insight into the specific role of hot carriers in plasmon-mediated photochemistry, which is critically important for designing energy-efficient plasmonic photocatalysts.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-12
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-12
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-12
    Description: Single-electron reduction of a carbonyl to a ketyl enables access to a polarity-reversed platform of reactivity for this cornerstone functional group. However, the synthetic utility of the ketyl radical is hindered by the strong reductants necessary for its generation, which also limit its reactivity to net reductive mechanisms. We report a strategy for net redox-neutral generation and reaction of ketyl radicals. The in situ conversion of aldehydes to α-acetoxy iodides lowers their reduction potential by more than 1 volt, allowing for milder access to the corresponding ketyl radicals and an oxidative termination event. Upon subjecting these iodides to a dimanganese decacarbonyl precatalyst and visible light irradiation, an atom transfer radical addition (ATRA) mechanism affords a broad scope of vinyl iodide products with high Z -selectivity.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Publication Date: 2018-10-12
    Description: Reactions that form a product with the same reactive functionality as that of one of the starting compounds frequently end in oligomerization. As a salient example, selective aldol coupling of the smallest, though arguably most useful, enolizable aldehyde, acetaldehyde, with just one partner substrate has proven to be extremely challenging. Here, we report a highly enantioselective Mukaiyama aldol reaction with the simple triethylsilyl (TES) and tert -butyldimethylsilyl (TBS) enolates of acetaldehyde and various aliphatic and aromatic acceptor aldehydes. The reaction is catalyzed by recently developed, strongly acidic imidodiphosphorimidates (IDPi), which, like enzymes, display a confined active site but, like small-molecule catalysts, have a broad substrate scope. The process is scalable, fast, efficient (0.5 to 1.5 mole % catalyst loading), and greatly simplifies access to highly valuable silylated acetaldehyde aldols.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-12-21
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Publication Date: 2018-12-21
    Description: Single-molecule magnets (SMMs) containing only one metal center may represent the lower size limit for molecule-based magnetic information storage materials. Their current drawback is that all SMMs require liquid-helium cooling to show magnetic memory effects. We now report a chemical strategy to access the dysprosium metallocene cation [(Cp i Pr5 )Dy(Cp*)] + (Cp i Pr5 , penta-iso-propylcyclopentadienyl; Cp *, pentamethylcyclopentadienyl), which displays magnetic hysteresis above liquid-nitrogen temperatures. An effective energy barrier to reversal of the magnetization of U eff = 1541 wave number is also measured. The magnetic blocking temperature of T B = 80 kelvin for this cation overcomes an essential barrier toward the development of nanomagnet devices that function at practical temperatures.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-19
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-19
    Description: The development of highly reactive and stereoselective catalytic systems is required not only to improve existing synthetic methods but also to invent distinct chemical reactions. Herein, a homogenized combination of nickel-based Lewis acid–surfactant-combined catalysts and single-walled carbon nanotubes is shown to exhibit substantial activity in water. In addition to the enhanced reactivity, stereoselective performance and long-term stability were demonstrated in asymmetric conjugate addition reactions of aldoximes to furnish chiral nitrones in high yields with excellent selectivities. The practical and straightforward application of the designed catalysts in water provides an expedient, environmentally benign, and highly efficient pathway to access optically active compounds.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-11-02
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-12-14
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-26
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-11-02
    Description: Exploration of intermediates that enable chemoselective cycloaddition reactions and expeditious construction of fused- or bridged-ring systems is a continuous challenge for organic synthesis. As an intermediate of interest, the oxyallyl cation has been harnessed to synthesize architectures containing seven-membered rings via (4+3) cycloaddition. However, its potential to access five-membered skeletons is underdeveloped, largely due to the thermally forbidden (3+2) pathway. Here, the combination of a tailored precursor and a Pd(0) catalyst generates a Pd-oxyallyl intermediate that cyclizes with conjugated dienes to produce a diverse array of tetrahydrofuran skeletons. The cycloaddition overrides conventional (4+3) selectivity by proceeding through a stepwise pathway involving a Pd-allyl transfer and ring closure sequence. Subsequent treatment of the (3+2) adducts with a palladium catalyst converts the heterocycles to the carbocyclic cyclopentanones.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-11-16
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-10
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Publication Date: 2018-08-10
    Description: Understanding the practical limitations of chemical reactions is critically important for efficiently planning the synthesis of compounds in pharmaceutical, agrochemical, and specialty chemical research and development. However, literature reports of the scope of new reactions are often cursory and biased toward successful results, severely limiting the ability to predict reaction outcomes for untested substrates. We herein illustrate strategies for carrying out large-scale surveys of chemical reactivity by using a material-sparing nanomole-scale automated synthesis platform with greatly expanded synthetic scope combined with ultrahigh-throughput matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI-TOF MS).
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Publication Date: 2018-08-24
    Description: Researchers around the world have observed the formation of molecularly ordered structures of unknown origin on the surface of titanium dioxide (TiO 2 ) photocatalysts exposed to air and solution. Using a combination of atomic-scale microscopy and spectroscopy, we show that TiO 2 selectively adsorbs atmospheric carboxylic acids that are typically present in parts-per-billion concentrations while effectively repelling other adsorbates, such as alcohols, that are present in much higher concentrations. The high affinity of the surface for carboxylic acids is attributed to their bidentate binding. These self-assembled monolayers have the unusual property of being both hydrophobic and highly water-soluble, which may contribute to the self-cleaning properties of TiO 2 . This finding is relevant to TiO 2 photocatalysis, because the self-assembled carboxylate monolayers block the undercoordinated surface cation sites typically implicated in photocatalysis.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-31
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-31
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Publication Date: 2018-08-31
    Description: The alkaline earth metals calcium (Ca), strontium (Sr), and barium (Ba) typically engage in chemical bonding as classical main-group elements through their n s and n p valence orbitals, where n is the principal quantum number. Here we report the isolation and spectroscopic characterization of eight-coordinate carbonyl complexes M(CO) 8 (where M = Ca, Sr, or Ba) in a low-temperature neon matrix. Analysis of the electronic structure of these cubic O h -symmetric complexes reveals that the metal–carbon monoxide (CO) bonds arise mainly from [M(d )] -〉 (CO) 8 backdonation, which explains the strong observed red shift of the C-O stretching frequencies. The corresponding radical cation complexes were also prepared in gas phase and characterized by mass-selected infrared photodissociation spectroscopy, confirming adherence to the 18-electron rule more conventionally associated with transition metal chemistry.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-07
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Publication Date: 2018-09-07
    Description: Mystery surrounds the transition from gas-phase hydrocarbon precursors to terrestrial soot and interstellar dust, which are carbonaceous particles formed under similar conditions. Although polycyclic aromatic hydrocarbons (PAHs) are known precursors to high-temperature carbonaceous-particle formation, the molecular pathways that initiate particle formation are unknown. We present experimental and theoretical evidence for rapid molecular clustering–reaction pathways involving radicals with extended conjugation. These radicals react with other hydrocarbon species to form covalently bound complexes that promote further growth and clustering by regenerating resonance-stabilized radicals through low-barrier hydrogen-abstraction and hydrogen-ejection reactions. Such radical–chain reaction pathways may lead to covalently bound clusters of PAHs and other hydrocarbons that would otherwise be too small to condense at high temperatures, thus providing the key mechanistic steps for rapid particle formation and surface growth by hydrocarbon chemisorption.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-14
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-04-27
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-04-27
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-04-27
    Description: Basic heteroarenes are a ubiquitous feature of pharmaceuticals and bioactive molecules, and Minisci-type additions of radical nucleophiles are a leading method for their elaboration. Despite many Minisci-type protocols that result in the formation of stereocenters, exerting control over the absolute stereochemistry at these centers remains an unmet challenge. We report a process for addition of prochiral radicals, generated from amino acid derivatives, to pyridines and quinolines. Our method offers excellent control of both enantioselectivity and regioselectivity. An enantiopure chiral Brønsted acid catalyst serves both to activate the substrate and induce asymmetry, while an iridium photocatalyst mediates the required electron transfer processes. We anticipate that this method will expedite access to enantioenriched small-molecule building blocks bearing versatile basic heterocycles.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-05-25
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-05-25
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Publication Date: 2018-10-26
    Description: Primary amines are essential constituents of biologically active molecules and versatile intermediates in the synthesis of drugs and agrochemicals. However, their preparation from easily accessible alkenes remains challenging. Here, we report a general strategy to access primary amines from alkenes through an operationally simple iron-catalyzed aminochlorination reaction. A stable hydroxylamine derivative and benign sodium chloride act as the respective nitrogen and chlorine sources. The reaction proceeds at room temperature under air; tolerates a large scope of aliphatic and conjugated alkenes, including densely functionalized substrates; and provides excellent anti-Markovnikov regioselectivity with respect to the amino group. The reactivity of the 2-chloroalkylamine products, an understudied class of amphoteric molecules, enables facile access to linear or branched aliphatic amines, aziridines, aminonitriles, azido amines, and homoallylic amines.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-11-09
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Publication Date: 2018-11-09
    Description: Despite the enormous potential for the use of stereospecific cross-coupling reactions to rationally manipulate the three-dimensional structure of organic molecules, the factors that control the transfer of stereochemistry in these reactions remain poorly understood. Here we report a mechanistic and synthetic investigation into the use of enantioenriched alkylboron nucleophiles in stereospecific Pd-catalyzed Suzuki cross-coupling reactions. By developing a suite of molecular descriptors of phosphine ligands, we could apply predictive statistical models to select or design distinct ligands that respectively promoted stereoinvertive and stereoretentive cross-coupling reactions. Stereodefined branched structures were thereby accessed through the predictable manipulation of absolute stereochemistry, and a general model for the mechanism of alkylboron transmetallation was proposed.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Publication Date: 2018-11-16
    Description: Heterobiaryls composed of pyridine and diazine rings are key components of pharmaceuticals and are often central to pharmacological function. We present an alternative approach to metal-catalyzed cross-coupling to make heterobiaryls using contractive phosphorus C–C couplings, also termed phosphorus ligand coupling reactions. The process starts by regioselective phosphorus substitution of the C–H bonds para to nitrogen in two successive heterocycles; ligand coupling is then triggered via acidic alcohol solutions to form the heterobiaryl bond. Mechanistic studies imply that ligand coupling is an asynchronous process involving migration of one heterocycle to the ipso position of the other around a central pentacoordinate P(V) atom. The strategy can be applied to complex drug-like molecules containing multiple reactive sites and polar functional groups, and also enables convergent coupling of drug fragments and late-stage heteroarylation of pharmaceuticals.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-07-06
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Publication Date: 2018-07-06
    Description: Conical intersections play a critical role in excited-state dynamics of polyatomic molecules because they govern the reaction pathways of many nonadiabatic processes. However, ultrafast probes have lacked sufficient spatial resolution to image wave-packet trajectories through these intersections directly. Here, we present the simultaneous experimental characterization of one-photon and two-photon excitation channels in isolated CF 3 I molecules using ultrafast gas-phase electron diffraction. In the two-photon channel, we have mapped out the real-space trajectories of a coherent nuclear wave packet, which bifurcates onto two potential energy surfaces when passing through a conical intersection. In the one-photon channel, we have resolved excitation of both the umbrella and the breathing vibrational modes in the CF 3 fragment in multiple nuclear dimensions. These findings benchmark and validate ab initio nonadiabatic dynamics calculations.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-07-13
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...