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  • Chemistry
  • American Association for the Advancement of Science (AAAS)  (342)
  • Iranian Fisheries Science Research Institute  (12)
  • 1
    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.
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  • 2
    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.
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  • 3
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    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
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  • 4
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    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
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  • 5
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    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
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  • 6
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    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
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  • 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
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  • 8
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    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
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  • 9
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    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
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  • 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
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  • 11
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    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
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  • 12
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    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
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  • 13
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-07-08
    Description: Separation and purification are critical industrial processes for separating components of chemical mixtures, and these processes account for about half of industrial energy usage (1). Gas mixtures of compounds with very similar physical properties are particularly difficult to separate. On pages 137 and 141 of this issue, Cadiau et al. (2) and Cui et al. (3), respectively, show that microporous materials can be designed to have high adsorption capacity and selectivity for particular hydrocarbons, enabling energy-efficient separation. Author: Jerry Y. S. Lin
    Keywords: Chemistry
    Print ISSN: 0036-8075
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  • 14
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-05-27
    Description: Biomass-degrading microorganisms use lytic polysaccharide monooxygenase (LPMO) enzymes to help digest cellulose, chitin, and starch. By cleaving otherwise inaccessible crystalline cellulose chains, these enzymes provide access to hydrolytic enzymes. LPMOs are of interest to biotechnology because efficient depolymerization of cellulose is a major bottleneck for the production of biologically based chemicals and fuels. On page 1098 of this issue, Kracher et al. (1) compare LPMO-reducing substrates in fungi from different taxonomic groups and lifestyles, based on both biochemical and genomic evidence. The results provide insights into reductive activation of LPMO that are important for developing more efficient industrial enzymes for lignocellulose biorefineries. Author: Angel T. Martínez
    Keywords: Chemistry
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  • 15
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-03-25
    Description: Author: Marc S. Lavine
    Keywords: Chemistry
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  • 16
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-05-31
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Demaine, Linda J -- Fellmeth, Aaron X -- New York, N.Y. -- Science. 2003 May 30;300(5624):1375-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉RAND, Santa Monica, CA 90401, USA. demaine@rand.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12775825" target="_blank"〉PubMed〈/a〉
    Keywords: Aluminum Oxide ; Chemical Phenomena ; Chemistry ; Natural Science Disciplines ; Patents as Topic/*legislation & jurisprudence ; Plant Extracts ; Plant Roots ; Titanium ; United States
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  • 17
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-03-16
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Eisner, Thomas -- Berenbaum, May -- New York, N.Y. -- Science. 2002 Mar 15;295(5562):1973.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11896239" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biochemical Phenomena ; *Biochemistry ; *Biological Factors/chemistry ; *Biology ; Chemical Phenomena ; Chemistry ; *Ecology ; Ecosystem ; *Molecular Biology ; Research Support as Topic ; United States
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  • 18
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-08-19
    Description: The question of how the primary amino acid sequence of a protein determines its three-dimensional structure is still unanswered. One approach to this problem involves the de novo design of model peptides and proteins that should adopt desired three-dimensional structures. A systematic approach was aimed at the design of a four-helix bundle protein. The gene encoding the designed protein was synthesized and the protein was expressed in Escherichia coli and purified to homogeneity. The protein was shown to be monomeric, highly helical, and very stable to denaturation by guanidine hydrochloride (GuHCl). Thus a globular protein has been designed that is capable of adopting a stable, folded structure in aqueous solution.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Regan, L -- DeGrado, W F -- New York, N.Y. -- Science. 1988 Aug 19;241(4868):976-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉E. I. du Pont de Nemours & Company, Central Research & Development Department, Wilmington, DE 19898.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3043666" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Chemical Phenomena ; Chemistry ; Chromatography, Gel ; Escherichia coli/genetics ; Molecular Sequence Data ; Plasmids ; *Protein Conformation ; *Proteins/genetics
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  • 19
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-03-03
    Description: Monoclonal antibodies have been induced that are capable of catalyzing specific hydrolysis of the Gly-Phe bond of peptide substrates at neutral pH with a metal complex cofactor. The antibodies were produced by immunizing with a Co(III) triethylenetetramine (trien)-peptide hapten. These antibodies as a group are capable of binding trien complexes of not only Co(III) but also of numerous other metals. Six peptides were examined as possible substrates with the antibodies and various metal complexes. Two of these peptides were cleaved by several of the antibodies. One antibody was studied in detail, and cleavage was observed for the substrates with the trien complexes of Zn(II), Ga(III), Fe(III), In(III), Cu(II), Ni(II), Lu(III), Mg(II), or Mn(II) as cofactors. A turnover number of 6 x 10(-4) per second was observed for these substrates. These results demonstrate the feasibility of the use of cofactor-assisted catalysis in an antibody binding site to accomplish difficult chemical transformations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Iverson, B L -- Lerner, R A -- New York, N.Y. -- Science. 1989 Mar 3;243(4895):1184-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2922606" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; *Antibodies, Monoclonal ; Antigens/immunology ; Binding Sites, Antibody ; Catalysis ; Chemical Phenomena ; Chemistry ; Cobalt/immunology/metabolism ; Glycine/metabolism ; Haptens/immunology ; Hydrogen-Ion Concentration ; Hydrolysis ; Immunization ; Metals/metabolism ; Mice ; Molecular Sequence Data ; Molecular Structure ; Oligopeptides/*metabolism ; Phenylalanine/metabolism ; Trientine/immunology
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  • 20
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-02-16
    Keywords: Chemistry
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  • 21
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    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
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  • 22
    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
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  • 23
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-07-27
    Keywords: Chemistry
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  • 24
    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
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  • 25
    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
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  • 26
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-06-29
    Keywords: Chemistry
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  • 27
    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
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  • 28
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-17
    Keywords: Chemistry
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  • 29
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-17
    Keywords: Chemistry
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  • 30
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    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
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  • 31
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-17
    Keywords: Chemistry
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  • 32
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    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
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  • 33
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-24
    Keywords: Chemistry
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  • 34
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-24
    Keywords: Chemistry
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  • 35
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-31
    Keywords: Chemistry
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  • 36
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    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
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  • 37
    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
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  • 38
    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
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  • 39
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-28
    Keywords: Chemistry
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  • 40
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-28
    Keywords: Chemistry
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  • 41
    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
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  • 42
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    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
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  • 43
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-05
    Keywords: Chemistry
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  • 44
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-05
    Keywords: Chemistry
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  • 45
    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
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  • 46
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-12
    Keywords: Chemistry
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  • 47
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-12
    Keywords: Chemistry
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  • 48
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    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
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  • 49
    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
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  • 50
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-12-21
    Keywords: Chemistry
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  • 51
    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
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  • 52
    Publication Date: 1989-11-17
    Description: The surface forces apparatus technique was used for measuring the adhesion, deformation, and fusion of bilayers supported on mica surfaces in aqueous solutions. The most important force leading to the direct fusion of bilayers is the hydrophobic interaction, although the occurrence of fusion is not simply related to the force law between bilayers. Bilayers do not need to "overcome" some repulsive force barrier, such as hydration, before they can fuse. Instead, once bilayer surfaces come within about 1 nanometer of each other, local deformations and molecular rearrangements allow them to "bypass" these forces.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Helm, C A -- Israelachvili, J N -- McGuiggan, P M -- New York, N.Y. -- Science. 1989 Nov 17;246(4932):919-22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemical and Nuclear Engineering, University of California, Santa Barbara 93106.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2814514" target="_blank"〉PubMed〈/a〉
    Keywords: Chemical Phenomena ; Chemistry ; *Lipid Bilayers ; Models, Biological ; Models, Structural ; Phosphatidylcholines ; Phosphatidylethanolamines
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  • 53
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-07-28
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Waldrop, M M -- New York, N.Y. -- Science. 1989 Jul 28;245(4916):354-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2756423" target="_blank"〉PubMed〈/a〉
    Keywords: *Catalysis ; Chemical Phenomena ; Chemistry ; *Enzymes ; Technology, Pharmaceutical
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  • 54
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-03
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Waldrop, M M -- New York, N.Y. -- Science. 1990 Aug 3;249(4968):472-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2382127" target="_blank"〉PubMed〈/a〉
    Keywords: Chemical Phenomena ; Chemistry ; *Information Systems ; Jurisprudence ; Societies, Scientific ; United States
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  • 55
    Publication Date: 1991-10-25
    Description: The presence of clathrate hydrates in cometary ice has been suggested to account for anomalous gas release at large radial distances from the sun as well as the retention of volatiles in comets to elevated temperatures. However, how clathrate hydrates can form in low-pressure environments, such as in cold interstellar molecular clouds, in the outer reaches of the early solar nebula, or in cometary ices, has been poorly understood. Experiments performed with the use of a modified electron microscope demonstrate that during the warming of vapor-deposited amorphous ices in vacuo, clathrate hydrates can form by rearrangements in the solid state. Phase separations and microporous textures that are the result of these rearrangements may account for a variety of anomalous cometary phenomena.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Blake, D -- Allamandola, L -- Sandford, S -- Hudgins, D -- Freund, F -- New York, N.Y. -- Science. 1991 Oct 25;254:548-51.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Planetary Biology Branch, Ames Research Center, Moffett Field, CA 94035, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11538372" target="_blank"〉PubMed〈/a〉
    Keywords: Chemical Phenomena ; Chemistry ; Crystallography ; Earth (Planet) ; Hydrocarbons/chemistry ; Ice/*analysis ; *Meteoroids ; Microscopy, Electron ; *Solar System
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  • 56
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-05-26
    Description: Methods for the design and synthesis of ligands intended to be specific for a metal ion have been a recent chemical development. This article describes how this process can be inverted so that the specifics of the coordination environment around the metal ion can be used as a template in large-scale ligand synthesis. The synthesis of macrobicyclic ligands for ferric ion has been accomplished by using active esters of catechol ligands in which catecholate coordination to iron is a prelude to the organic chemical reactions that link the coordination subunits together into one ligand system surrounding a central metal ion coordination site. The lanthanide(III) ions, which are among the most labile metal ions known, have coordination numbers of 8 or higher, and thus their encapsulation into a macrobicyclic structure is a challenging problem. Lanthanide amine complexes have been used as metal templates in the synthesis of such macrobicyclic lanthanide complexes. There is evidence that such a complex is inert to exchange in aqueous solution.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McMurry, T J -- Raymond, K N -- Smith, P H -- New York, N.Y. -- Science. 1989 May 26;244(4907):938-43.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Radiation Oncology Branch, National Cancer Institute, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2658057" target="_blank"〉PubMed〈/a〉
    Keywords: Cations ; Chemical Phenomena ; Chemistry ; Iron/metabolism ; *Ligands ; Macromolecular Substances ; Metals/*metabolism ; Metals, Rare Earth/metabolism ; Molecular Structure ; Templates, Genetic
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  • 57
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-02-17
    Description: Mechanistic and synthetic studies in organometallic chemistry have provided considerable insight into olefin metathesis and Ziegler-Natta polymerization. New homogeneous olefin metathesis catalysts based on high oxidation state transition metals have opened new opportunities in polymer synthesis by providing unprecedented control in ring-opening polymerization of cyclic alkenes. The recent development of living coordinative polymerization systems has led to the preparation of a number of new, interesting materials, including block copolymers, conducting polymers or precursors, and ionophoric polymeric substrates.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grubbs, R H -- Tumas, W -- New York, N.Y. -- Science. 1989 Feb 17;243(4893):907-15.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉California Institute of Technology, Pasadena 91125.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2645643" target="_blank"〉PubMed〈/a〉
    Keywords: Chemical Phenomena ; Chemistry ; *Organometallic Compounds ; *Polymers
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  • 58
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-09-14
    Description: Direct osmotic stress measurements have been made of forces between helices of xanthan, an industrially important charged polysaccharide. Exponentially decaying hydration forces, much like those already measured between lipid bilayer membranes or DNA double helices, dominate the interactions at close separation. Interactions between uncharged schizophyllans also show the same kind of hydration force seen between xanthans. In addition to the practical possibilities for modifying solution and suspension properties through recognition and control of molecular forces, there is now finally the opportunity for theorists to relate macroscopic properties of a polymer solution to the microscopic properties that underlie them.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rau, D C -- Parsegian, V A -- New York, N.Y. -- Science. 1990 Sep 14;249(4974):1278-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Biochemistry and Metabolism, National Institute of Diabetes and Digestive and Kidney Diseases, National Institues of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2144663" target="_blank"〉PubMed〈/a〉
    Keywords: Carbohydrate Sequence ; Chemical Phenomena ; Chemistry ; Gels ; *Glycosaminoglycans ; Macromolecular Substances ; Molecular Sequence Data ; Osmosis ; *Polysaccharides, Bacterial ; *Sizofiran ; Solutions ; Viscosity
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  • 59
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-02-02
    Description: Protein unfolding and the dissolution of hydrophobic compounds (including solids, liquids, and gases) in water are characterized by a linear relation between entropy change and heat capacity change. The same slope is found for various classes of compounds, whereas the intercept depends on the particular class. The feature common to these processes is exposure of hydrophobic groups to water. These observations make possible the assignment of the heat capacity change to hydrophobic solvation and lead to the description of protein stability in terms of a hydrophobic and a nonhydrophobic contribution. A general representation of protein stability is given by the heat capacity change and the temperature.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murphy, K P -- Privalov, P L -- Gill, S J -- New York, N.Y. -- Science. 1990 Feb 2;247(4942):559-61.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2300815" target="_blank"〉PubMed〈/a〉
    Keywords: Chemical Phenomena ; Chemistry ; *Protein Denaturation ; *Proteins ; Thermodynamics
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  • 60
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-03-02
    Description: Ultrasound has become an important synthetic tool in liquid-solid chemical reactions, but the origins of the observed enhancements remained unknown. The effects of high-intensity ultrasound on solid-liquid slurries were examined. Turbulent flow and shock waves produced by acoustic cavitation were found to drive metal particles together at sufficiently high velocities to induce melting upon collision. A series of transition-metal powders were used to probe the maximum temperatures and speeds reached during such interparticle collisions. Metal particles that were irradiated in hydrocarbon liquids with ultrasound underwent collisions at roughly half the speed of sound and generated localized effective temperatures between 2600 degrees C and 3400 degrees C at the point of impact for particles with an average diameter of approximately 10 microns.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Doktycz, S J -- Suslick, K S -- New York, N.Y. -- Science. 1990 Mar 2;247(4946):1067-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Chemical Sciences, University of Illinois, Urbana 61801.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2309118" target="_blank"〉PubMed〈/a〉
    Keywords: Chemical Phenomena ; Chemistry ; *Metals ; Microscopy, Electron, Scanning ; Microspheres ; *Ultrasonics
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  • 61
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-01-12
    Description: Experiments are presented that confirm earlier predictions that the mode of supply of reactants to a nonlinear (bio)chemical reaction determines or controls concentrations at steady states far from equilibrium. The oxidation of nicotinamide adenine dinucleotide (NADH) catalyzed by the enzyme horseradish peroxidase with continuous input of oxygen was studied; NAD+ is continuously recycled to NADH through a glucose-6-phosphate dehydrogenase system. A comparison of steady-state concentrations is made with an oscillatory oxygen input and a constant input at the same average oxygen input for both modes. By varying the frequency and amplitude of the perturbation (O2 influx), the following may be changed: the average concentration of NADH; the Gibbs free energy difference delta G of the reactants and products at steady state; the average rate of the reaction; the phase relation between the oscillatory rate and delta G; and the dissipation. These results confirm the possibility of an "alternating current chemistry," of control and optimization of thermodynamic efficiency and dissipation by means of external variation of constraints in classes of nonlinear reactions and biological pumps, and of improvements of the yield in such reactions (heterogeneous catalysis, for example).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lazar, J G -- Ross, J -- New York, N.Y. -- Science. 1990 Jan 12;247(4939):189-92.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Stanford University, CA 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2294601" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Chemical Phenomena ; Chemistry ; Glucosephosphate Dehydrogenase/*metabolism ; Horseradish Peroxidase/*metabolism ; Kinetics ; NAD/*metabolism ; Oxidation-Reduction ; Oxygen/metabolism ; Peroxidases/*metabolism ; Thermodynamics
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  • 62
    Publication Date: 1990-08-17
    Description: The interaction of a protein antigen, horse cytochrome c (cyt c), with a monoclonal antibody has been studied by hydrogen-deuterium (H-D) exchange labeling and two-dimensional nuclear magnetic resonance (2D NMR) methods. The H-exchange rate of residues in three discontiguous regions of the cyt c polypeptide backbone was slowed by factors up to 340-fold in the antibody-antigen complex compared with free cyt c. The protected residues, 36 to 38, 59, 60, 64 to 67, 100, and 101, and their hydrogen-bond acceptors, are brought together in the three-dimensional structure to form a contiguous, largely exposed protein surface with an area of about 750 square angstroms. The interaction site determined in this way is consistent with prior epitope mapping studies and includes several residues that were not previously identified. The hydrogen exchange labeling approach can be used to map binding sites on small proteins in antibody-antigen complexes and may be applicable to protein-protein and protein-ligand interactions in general.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3432411/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3432411/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Paterson, Y -- Englander, S W -- Roder, H -- GM 31847/GM/NIGMS NIH HHS/ -- GM 35926/GM/NIGMS NIH HHS/ -- R01 GM031847/GM/NIGMS NIH HHS/ -- S07-RR-05415-28/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 17;249(4970):755-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, University of Pennsylvania, Philadelphia 19104.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1697101" target="_blank"〉PubMed〈/a〉
    Keywords: Antibodies, Monoclonal/immunology/metabolism ; Antigen-Antibody Complex ; *Binding Sites, Antibody ; Chemical Phenomena ; Chemistry ; Cytochrome c Group/*immunology ; Deuterium ; Epitopes/immunology ; Hydrogen/*metabolism ; Hydrogen Bonding ; Kinetics ; *Magnetic Resonance Spectroscopy ; Molecular Structure ; Protein Conformation
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  • 63
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1991-07-12
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Baskin, Y -- New York, N.Y. -- Science. 1991 Jul 12;253(5016):140-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1853198" target="_blank"〉PubMed〈/a〉
    Keywords: *Academies and Institutes ; Biology ; California ; Chemical Phenomena ; Chemistry ; Research Support as Topic
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  • 64
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-02-23
    Description: Reactive or unstable molecules are key intermediates in many important reactions, but can be difficult to prepare for experimental studies. Species with missing (:CH-OH) or extra (H3) substituents can often be formed conveniently in the gas phase by neutralizing a beam of a more stable ionic counterpart (CH = O+H, H3+). Reionization of the neutral after approximately 10(-6) seconds tests its stability, whereas its unimolecular chemistry can be probed by preparing it with different amounts of internal energy. The resulting neutral products are reionized and mass analyzed. Isomers are then characterized by ion dissociation and a third mass-analysis step. Many unusual molecules have been characterized with this technique, which can also be used to probe complex unimolecular chemistry, such as that of cyclobutadiene and ethylene oxide.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McLafferty, F W -- GM-16609/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Feb 23;247(4945):925-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cornell University, Baker Laboratory, Ithaca, NY 14853-1301.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2305261" target="_blank"〉PubMed〈/a〉
    Keywords: Butadienes ; Chemical Phenomena ; Chemistry ; Ethylene Oxide ; Free Radicals ; Hydrocarbons ; *Ions ; *Mass Spectrometry ; Methane/analogs & derivatives ; Molecular Structure ; Thermodynamics
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  • 65
    Publication Date: 1990-05-18
    Description: The immunosuppressive agents cyclosporin A and FK506 inhibit the transcription of early T cell activation genes. The binding proteins for cyclosporin A and FK506, cyclophilin and FKBP, respectively, are peptidyl-prolyl-cis-trans isomerases, or rotamases. One proposed mechanism for rotamase catalysis by cyclophilin involves a tetrahedral adduct of an amide carbonyl and an enzyme-bound nucleophile. The potent FKBP rotamase inhibitor FK506 has a highly electrophilic carbonyl that is adjacent to an acyl-pipicolinyl (homoprolyl) amide bond. Such a functional group would be expected to form a stabilized, enzyme-bound tetrahedral adduct. Spectroscopic and chemical evidence reveals that the drug interacts noncovalently with its receptor, suggesting that the alpha-keto amid of FK506 serves as a surrogate for the twisted amide of a bound peptide substrate.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rosen, M K -- Standaert, R F -- Galat, A -- Nakatsuka, M -- Schreiber, S L -- GM-38627/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 May 18;248(4957):863-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Harvard University, Cambridge, MA 02138.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1693013" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Isomerases/*antagonists & inhibitors ; Anti-Bacterial Agents/metabolism/*pharmacology ; Binding Sites ; Carrier Proteins/antagonists & inhibitors/metabolism ; Chemical Phenomena ; Chemistry ; Cloning, Molecular ; Cyclosporins/metabolism/pharmacology ; Escherichia coli/genetics ; Gene Expression ; *Immunosuppressive Agents ; Lymphocyte Activation ; Magnetic Resonance Spectroscopy ; Molecular Structure ; Peptidylprolyl Isomerase ; Recombinant Proteins ; T-Lymphocytes/immunology ; Tacrolimus
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  • 66
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1991-05-03
    Description: Immunochemistry has historically focused on the nature of antigenicity and antibody-antigen recognition. However, in the last 5 years, the field of immunochemistry has taken a new direction. With the aid of mechanistic and synthetic chemistry, the vast network of molecules and cells of the immune system has been tapped to produce antibodies with a new function--catalytic antibodies. Because antibodies can be generated that selectively bind almost any molecule of interest, this new technology offers the potential to tailor-make highly selective catalysts for applications in biology, chemistry, and medicine. In addition, catalytic antibodies provide fundamental insight into important aspects of biological catalysis, including the importance of transition-state stabilization, proximity effects, general acid and base catalysts, electrophilic and nucleophilic catalysis, and strain.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lerner, R A -- Benkovic, S J -- Schultz, P G -- New York, N.Y. -- Science. 1991 May 3;252(5006):659-67.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2024118" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Antibodies/chemistry/immunology/metabolism ; Antibodies, Monoclonal/immunology/metabolism ; Antibody Specificity ; Antigens/chemistry/immunology/metabolism ; Binding Sites, Antibody ; *Catalysis ; Chemical Phenomena ; Chemistry ; Haptens ; Hydrogen-Ion Concentration ; Hydrolysis ; Metals ; Molecular Conformation ; Recombinant Proteins ; Thermodynamics ; Zinc
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  • 67
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2006-07-22
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Szathmary, Eors -- New York, N.Y. -- Science. 2006 Jul 21;313(5785):306-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Biology, Eotvos University Budapest, and Collegium Budapest (Institute for Advanced Study), 2 Szentharomsag utca, H-1014 Budapest, Hungary. szathmary@colbud.hu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16857926" target="_blank"〉PubMed〈/a〉
    Keywords: *Biological Evolution ; Chemical Phenomena ; Chemistry ; Computational Biology ; Cooperative Behavior ; Cultural Evolution ; Exobiology ; Humans ; Language ; Models, Biological ; Models, Theoretical ; Molecular Biology ; Origin of Life ; *Research ; Selection, Genetic
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2006-11-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Enserink, Martin -- New York, N.Y. -- Science. 2006 Nov 24;314(5803):1235-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17124302" target="_blank"〉PubMed〈/a〉
    Keywords: Chemistry ; *Cooking ; *Food ; France ; History, 20th Century ; History, 21st Century
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  • 69
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2005-05-10
    Description: Here we describe the requirements of an e-Infrastructure to enable faster, better, and different scientific research capabilities. We use two application exemplars taken from the United Kingdom's e-Science Programme to illustrate these requirements and make the case for a service-oriented infrastructure. We provide a brief overview of the UK "plug-and-play composable services" vision and the role of semantics in such an e-Infrastructure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hey, Tony -- Trefethen, Anne E -- New York, N.Y. -- Science. 2005 May 6;308(5723):817-21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Engineering and Physical Sciences Research Council, Polaris House, North Star Avenue, Swindon SN2 1ET, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15879209" target="_blank"〉PubMed〈/a〉
    Keywords: Chemical Phenomena ; Chemistry ; Combinatorial Chemistry Techniques ; *Computational Biology ; *Computer Communication Networks ; *Computing Methodologies ; Databases as Topic ; Graves Disease/genetics ; *Internet ; *Research ; *Software ; Williams Syndrome/genetics
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-05-29
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, David -- New York, N.Y. -- Science. 2004 May 28;304(5675):1283.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15166364" target="_blank"〉PubMed〈/a〉
    Keywords: Biotechnology ; Career Choice ; Chemistry ; Emigration and Immigration ; History, 20th Century ; History, 21st Century ; Siberia ; United States
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  • 71
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2005-10-22
    Description: If you trust the conventional wisdom, Amy Palmer and Alexis Templeton did a lot of things wrong in their job search. Then why did things turn out so right?〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Austin, Jim -- New York, N.Y. -- Science. 2005 Oct 21;310(5747):518-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16239480" target="_blank"〉PubMed〈/a〉
    Keywords: *Career Choice ; *Career Mobility ; Chemical Phenomena ; Chemistry ; Education, Graduate ; *Faculty ; Microbiology ; *Research ; United States ; *Universities
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  • 72
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-04-29
    Description: Author: Jake Yeston
    Keywords: Chemistry
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 73
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-03-18
    Description: Author: Marc S. Lavine
    Keywords: Chemistry
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  • 74
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-03-18
    Description: Water plays a central role in scientific disciplines ranging from geology to astronomy to biology. Yet it is an extraordinarily dif cult liquid to understand because of its complex, ever-changing patterns of hydrogen bonds. Studies of small water clusters have provided important insights into the concerted hydrogen-bond motions that can occur in water. These studies are also crucial for developing an accurate potential function for simulating the properties of liquid water and ice (1). On page 1310 of this issue, Richardson et al. (2) provide evidence for a concerted type of motion in which two hydrogen bonds in a water cluster are broken simultaneously (see the figure). The results have implications for many areas of scientific study, including the chemistry of polar solvents, the conformations of proteins, and the dissolution of ions in minerals. Author: David C. Clary
    Keywords: Chemistry
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  • 75
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-03-18
    Description: Author: Jake Yeston
    Keywords: Chemistry
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 76
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-03-04
    Description: Lower olefins, particularly ethylene (C2H4), propylene (C3H6), and butylene (C4H8), are important intermediates in the manufacture of products such as plastics, solvents, paints, and medicines. They are produced worldwide in amounts exceeding 200 million tons per year (see the photo) (1), mostly from crude oil. More recent approaches use methanol or synthesis gas (syngas; a mixture of carbon monoxide and hydrogen) as feedstocks, but capital investments are high and/or selectivities to lower olefins limited. A bifunctional catalyst reported by Jiao et al. on page 1065 of this issue (2) enables the direct conversion of synthesis gas to lower olefins with a surprisingly high selectivity. Author: Krijn P. de Jong
    Keywords: Chemistry
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  • 77
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-19
    Keywords: Chemistry
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 78
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    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
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  • 79
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-11-02
    Keywords: Chemistry
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  • 80
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-12-14
    Keywords: Chemistry
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  • 81
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-10-26
    Keywords: Chemistry
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  • 82
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    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
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  • 83
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-11-16
    Keywords: Chemistry
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  • 84
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-09-02
    Description: Study of proteins that recognize specific DNA sequences has yielded much information, but the field is still in its infancy. Already two major structural motifs have been discovered, the helix-turn-helix and zinc finger, and numerous examples of DNA-binding proteins containing either of them are known. The restriction enzyme Eco RI uses yet a different motif. Additional motifs are likely to be found as well. There is a growing understanding of some of the physical chemistry involved in protein-DNA binding, but much remains to be learned before it becomes possible to engineer a protein that binds to a specific DNA sequence.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schleif, R -- New York, N.Y. -- Science. 1988 Sep 2;241(4870):1182-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate Department of Biochemistry, Brandeis University, Waltham, MA 02254.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2842864" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acids/metabolism ; Binding Sites ; Chemical Phenomena ; Chemistry ; DNA/metabolism ; DNA Restriction Enzymes/metabolism ; DNA-Binding Proteins/*metabolism ; Deoxyribonuclease EcoRI ; Electrochemistry ; Nucleic Acids/metabolism ; Protein Conformation ; Zinc
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  • 85
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-10
    Keywords: Chemistry
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  • 86
    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
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  • 87
    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
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  • 88
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-31
    Keywords: Chemistry
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  • 89
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-31
    Keywords: Chemistry
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  • 90
    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
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  • 91
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-07
    Keywords: Chemistry
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  • 92
    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
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  • 93
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-14
    Keywords: Chemistry
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-04-27
    Keywords: Chemistry
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-04-27
    Keywords: Chemistry
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  • 96
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    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
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  • 97
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-05-25
    Keywords: Chemistry
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  • 98
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-05-25
    Keywords: Chemistry
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  • 99
    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
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-11-09
    Keywords: Chemistry
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