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  • Articles  (407,099)
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  • Islamic Azad University, Science and Research Branch, Tehran, Marine Biology  (7)
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  • 1
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    Islamic Azad University, Science and Research Branch, Tehran, Marine Biology
    In:  http://aquaticcommons.org/id/eprint/19121 | 17408 | 2016-02-01 21:05:26 | 19121 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: Study on the biomarkers types to assess health status of marine ecosystems in environmental biomonitoring has an important value. Accordingly, accumulation of polycyclic aromatic hydrocarbons(PAHs) in sediment, water and tissues (liver and gill) of mudskipper(i.e. Boleophthalmus dussumieri) and some physiological responses like lysosomal membrane change performed on haemocytes, stability of red blood cell membrane and the Glutathione-S Transferase (GST) activity in the liver were measured in mudskipper. Samples were obtained from five sites along north western coast of the Persian Gulf (Khuzestan coast). Red blood cell membrane changes after different concentration of PAHs at different time was also studied to evaluate impact of PAHs compound on cell membrane. PAHs concentration was measured by HPLC method. The activity of GST enzyme was analysed by spectrophotometric method. Lysosomal membrane change was measured by NRR time method and stability of red blood cell membrane was evaluated by EOF test. Total PAH concentrations in the coastal sea water, the sediments, theliver and the gill tissues ranged between 0.80-18.34 μg/l, 113.50-3384.34 ng g-1 (dry weight), 3.99-46.64 ng g-1 dw and 3.11-17.76 ng g-1 dw, respectively.Highest PAHs pollution was found at Jafari while the lowest was detected at Bahrakan sampling sites. The lowest enzymatic activity was identified at Bahrakan (7.19 ± 1.541 nmol/mg protein/min), while the highest was recordedat Jafari (46.96 ± 7.877 nmol/mg protein/min). Comparative analysis of GST activity in the liver of mudskippers showed significant difference (p 〈 0.05) between the locations of Jafari and Bahrakan, and with other sites. Moreover, nosignificant difference was detected between the locations of Arvand, Zangi and Samayeli (p 〈 0.05). The mean RT was below 90 minutes in all sampling sites.Values of mean RT of the dye ranged from 34 (for the blood samples of mudskipper collected from Jafari site) to 78 minutes (for the blood samples of mudskipper collected from Bahrakan site). Spatial evaluation revealed the longest RT in fish from Bahrakan as compared with those from other sites.Preliminary results showed a significant difference (p 〈 0.05) among sampling sites except between Arvand and Zangi (p 〉 0.05). Osmotic fragility curves indicated that erythrocytes collected from mudskippers at Jafari were the most 009fragile followed by Zangi〉 Arvand〉 Samayeli〉 and Bahrakan. The mean erythrocyte fragility was significantly higher at Jafari site (p 〈 0.05) when compared to other sites. Significant differences were found between the varioussites (p 〈 0.05).The result indicated no significant differences between the control and treatments of mudskipper RBC exposed to field concentrations of PAHs (P〉0.05). The results further indicated significant differences (P〈0.05) between the control and treatments of mudskipper RBC exposed to acute. Potency Divisor concentrations. It is clear from the present result that chronic. Potency Divisor concentrations protect red cells against osmotic hemolysis. This study, however, showed that PAH concentrations in this region are not higher than the available standards. The findings showed that Lysosomal membrane destabilization, liver GST activities and fragility of red cell membrane are highly sensitive in the mudskipper, B. dussumieri. Thus, mudskipper perceived to begood sentinel organisms for PAH pollution monitoring. Sediment PAH concentrations were strongly correlated with biomarkers, indicating that PAH type pollutants were biologically available to fish. One of the possible riskassessment implications of this study is that biomarkers can be applied not only to characterize biological effects of pollution exposures, but also to determine the bioavailability of pollution in aquatic systems. The results also indicated that PAHs compound possess anti haemolytic property.
    Description: PhD
    Description: Advisors:P. Eghtesadi Araghi, A. Mashinchian Counsellors: M. R. Fatemi, G. Riazi
    Keywords: Biology ; Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
    Format: application/pdf
    Format: application/pdf
    Format: 134
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  • 2
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    Islamic Azad University, Science and Research Branch, Tehran, Marine Biology
    In:  http://aquaticcommons.org/id/eprint/20998 | 17408 | 2016-08-17 09:39:37 | 20998 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: Oxidative refolding is one of the key challenges hampering the development of peptide based compounds as therapeutics. The correct refolding for three disulfide peptide like w-Conotoxi n MVIIA is difficult and crucial for biological activity. This work advanced knowledge of chemical and biological for improve oxidative refolding of synthetic w-Conotoxi n MVIIA in base of Conus magus venom. The present study aimed to set up an appropriate and effective protocols for refolding of disulfide-rich w-Conotoxin MVIIA. In this study, the crude peptide was protected with Acm group, according to the right amino acid sequences (Synthesized by Australian Company). The crude peptide was purified by H PLC. To prepare the peptide to refolding, innovative deprotection applied molar ratio (AMR) method was performed based on mercury. Accuracy of deprotection was approved by reverse phase chromatography. The deprotected target peptide (omega-conotoxin) was determined by SDS-PAGE. Then the Oxidative refolding of target peptide was performed in six protocol based on Guanidinium chloride and oxidized and reduced Glutathione. Analgesic effect of refolded peptide was surveyed with formalin test in mice Balb/c. Non neurotoxic effects of target peptides were survey with ICV injection in mice model (C57/BL6). The innovative deprotection protocol performed based on the best ratio of mercury/2-mercaptoethanol adjusted to 1mg/10p1 in 90 minute. The results showed the yield and purity of omega-conotoxin MVIIA as 93 and 95%, respectively. Refolding of 40 mg omega Conotoxin with GSSG and GSH on ratio of 10:1 and 20 mM ammonium acetate showed the best analgesic effect compared with the other methods. The result showed 95.5% yield and 98% purity of omega-conotoxin MVIIA in this refolding method. Related refolding method reduced 85% pain in experimented mice using 7 ng of the peptide. That was 71.5 fold stronger than morphine and 2 times than standard Prialt®. And it was not neurotoxic in mice. In this study, refolding method for omega-conotoxin MVIIA was optimized in the fourth factor including: reducing the time, amount and number of reagent and increase the efficiency. We introduced new method for deprotection of omega-conotoxin MVIIA. Effective, economic and applied refolding and deprotecti on method was performed in this research may al so be applied to similar omega conotoxin peptides.
    Description: PhD
    Description: Advisors: Delavar, Shahbazzadeh; Shahla, Jamili; counsellors: Kamran, Pooshang Bagheri; Pargol, Ghavam Mostafavi
    Keywords: Biology ; Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
    Format: application/pdf
    Format: application/pdf
    Format: 120
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  • 3
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    Islamic Azad University, Science and Research Branch, Tehran, Marine Biology
    In:  http://aquaticcommons.org/id/eprint/21024 | 17408 | 2016-08-24 10:11:29 | 21024 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: Sponges are the most primitive of the multicellular, These organisms don’t have any mechanical defense system, so their early appearance in evolution has given them a lot of time for the development of advanced secondary metabolites as chemical defense system. Sponges have the potential to provide drugs from chemical components against diseases. In this investigation the sponge samples, which it is Ircina spp., were collected at depth of 15- 24 meter, from locations on the coastline of Island Kish in Persian Gulf of Iran. For identifying natural components, methanolic and diethyletter were used as extraction solvents, after removal of the solvents, the GC/MS spectra of the fraction were obtained. Then in vitro cytotoxic, antimicrobial and antifungal were identified. In vitro cytotoxity screening, by XTT assay, against KB/ C359 and HUT-56/ C365 cell line, was conducted in this study in 1 - 544 μg/ml. IC54 for winter diethyletter extract was 325 μg/ml, winter methanolic extract was 364 μg/ml, IC54 for summer diethyletter extract was 544 μg/ml, and summer methanolic extract was 454 μg/ml in HUT-56. IC54 for winter diethyletter extract was 454 μg/ml, winter methanolic extract was 444 μg/ml, IC54 for summer diethyletter extract was 344 μg/ml, and summer methanolic extract was 424 μg/ml in KB. In vitro antimicrobial activity by Broth Dilution Methods against clinical gram-positives and gram negatives (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis). The results conducted that the MIC values of winter diethyletter extract for Escherichia coli 24mg/ml, the MIC values of winter diethyletter extract for Escherichia coli 24mg/ml, the MIC and MBC values of winter diethyletter extract for Staphylococcus aureus was 2mg/ml and 24mg/ml. The MIC and MBC values of winter diethyletter extract for Bacillus subtilis was 1.5 mg/ml and 2mg/ml. In vitro antifungal activity by Broth Dilution Methods against clinical pathogens; Candida albicans and Aspergillus fumigatus. The results conducted that the aqueous extracts didn’t have any antifungal activities on pathogens, the MFC of the summer and winter diethyletter extract was 30 mg/ml and 2 mg/ml A. fumigates, the summer and winter methanolic extract was 0722 mg/ml and 2 mg/ml A. fumigates, the summer and winter methanolic was 4/75mg/ml, MFC 5 mg/ml on C. albicans.
    Description: PhD
    Description: Advisors: A. A., Motallebi; SH., Jamili; Counsellors: A., Mashinchian; P., Gavam Mostafavi
    Keywords: Biology ; Chemistry ; Fisheries ; Health
    Repository Name: AquaDocs
    Type: thesis
    Format: application/pdf
    Format: application/pdf
    Format: 162
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  • 4
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    Islamic Azad University, Science and Research Branch, Tehran, Marine Biology
    In:  http://aquaticcommons.org/id/eprint/21650 | 17408 | 2017-11-14 09:22:12 | 21650 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-06-27
    Description: Toxins produced by flora and fauna and its proteins as well as valuable pharmaceutical compounds. They contain proteins used in producing painkillers, drugs for treating cancer, infectious diseases, allergy, blood pressure, etc. In this study on 250 blackfin stonefish, we investigated the LD50 and hematological effects of the toxin produced by this fish along with its pharmacological and enzymatic properties investigated by other researchers. One and three LD50 of venom injected IM in Rabbits under study was administered IV and different parameter like PT, PTT, cbc total protein and SDS-PAGE venom electrophoreses were studied before and 24 hours after venom injection. The total protein was estimated 331 µg/ml and the level of RBC WBC were 6.62 and 7.1 mm3 before venom treatment and reduce to 6.3 and 5.7 mm3 after venom injection. The MCH=21 pg MCHC=32.6% Hb=13.95 g/dl HCT=42.8% were before venom treatment and reduce to MCV=65.3 fl MCH= 22 pg MCHC=33.7% Hb=12.7 g/dl HCT=37.7% after venom injection The PT and PTT reduce after venom treatment (before venom treatment were PT=8.5 second & PTT = 27 second and after venom injection PT=15 second & PTT = 34 second) the platelet count reduce after venom injection (before venom=495 103/microliter and after venom was 49 103/microliter). Our results showed that the venom caused a significant reduction In WBC, RBC Hb, Hct, and platelet count which is due to lysis of cell after venom treatment.
    Description: Masters
    Description: Advisors:Dr. Shahla Jamili; Dr. Hossein Zolfagharian
    Keywords: Biology ; Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
    Format: application/pdf
    Format: application/pdf
    Format: 101
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  • 5
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23422 | 19325 | 2018-04-25 19:24:46 | 23422 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: Tilapia guineensis eggs were spawned and hatched in different salinities (17, 12, 7, 5, 2 and 0) ppt. The study was conducted in eight replicates. The aim of the investigation was to ascertain disparity in hatching size of Tilapia guineensis attributable to salinity. Immediately hatching was observed, body weight of five hatchlings in each replicate was individually weighed in milligramme. The individual total length of the five hatchlings was also measured in millimeter. The height of the yolk sac larva was determined with micro-metre screw gauge graduated in millimeter from the top of the yolk sac to the dorsal region of the larva. Data obtained were used to calculate yolk sac volume. Significant differences (P〈0.01) were observed in body weight and total length of larvae hatched in different salinities. The heaviest and longest larvae were hatched in 12 ppt saline water. The yolk sac volume of larvae hatched in lower salinities were significantly higher (P〈0.01) than the yolk sac volume of larvae hatched in higher salinities. The smallest yolk sac volume was recorded in 12ppt saline water. Our findings show that salinity could be manipulated for economic production of heavier seeds of Tilapia.
    Description: Includes:- 5 tables.;6 refs.
    Keywords: Aquaculture ; Chemistry ; Tilapia guineensis ; Nigeria ; brackishwater environment ; Salinity effects ; Larvae
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 51-55
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  • 6
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    Fisheries Society of Nigeria | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23440 | 19325 | 2018-05-02 08:25:12 | 23440 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: The physical and chemical parameters of ABU Dam and Zaria Dam were carried out between September and October 2009. The results obtained in the two water bodies were temperature 27.7 0C, pH (7.5 and 7.3), dissolved oxygen (5.8 mg/l and 5.0 mg/l), biochemical oxygen demand (1.74 mg/l and 2. 16 mg/l), alkalinity (58 mg CaC03/l and 49 mgCaCO3/l) P04-P (2.47 mg/l and 1.59 mg/l) NO3-N (3.67 mg/l and 3.47 mg/l), conductivity (54.70 ~ks-1 and 42.48 ~ks-1), total hydrocarbon (TH) (47.66 mg/l) and 48.00 mg/l) and total dissolved solids (32.68 mg/l and 25.35 mg/l) respectively. There was no significant difference in the mean values of the parameters (P〉0.05) except conductivity and total dissolved solids. The water bodies were found to be neutral with high conductivity. All the properties in the water bodies were in conformity with international standards both for drinking and aquatic life.
    Description: Includes:- 2 tables.;7 refs.
    Keywords: Chemistry ; Limnology ; Pollution ; Nigeria ; Zaria Dam ; Nigeria ; ABU Dam ; freshwater environment ; Physicochemical properties ; Pollution
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 144-146
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  • 7
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    Fisheries Society of Nigeria | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23442 | 19325 | 2018-05-02 08:28:15 | 23442 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: In recent times there has been an upsurge in the culture of Tilapia in Nigeria resulting in increased demand for the fingerlings which is hardly satisfied. This is due to increasing demand for table size tilapia as food fish and under-sized tilapia in the fish meal and fish canning industries in Nigeria. Collection of Tilapia guineensis fingerlings from the wild, to augment hatchery production, has been the practice and this is subject to environmental fluctuations. Multivariate regression and correlation analyses of accumulated data were used to investigate the effects of changes in water quality parameters on abundance of fingerlings of Tilapia guineensis in a brackishwater habitat in Lagos. Dissolved oxygen (DO), salinity and secchi transparency were found to be the most dominant factors affecting the abundance of Tilapia guineensis fingerlings in the Lagos lagoon. Peak period of abundance was closely associated with period of low salinity (0.50%o to 5.60%o), which coincided with the period of low transparency and low DO in the rainy season. The correlation analyses of Tilapia guineensis fingerlings with the water quality parameters yielded the following correlation coefficients (r)- 0.598; (salinity); -0.644 (transparency); -0.710 (DO); -0.566; (temperature) and 0.129 (pH). The abundance of Tilapia guineensis fingerlings in the Lagoon was ultimately defined by a suitable regression equation. This result is expected to optimize the collection of fingerlings of Tilapia guineensis from the wild and boost food fish security in Nigeria and elsewhere.
    Description: Includes:- 1 table.;1 fig.;( refs.
    Keywords: Chemistry ; Fisheries ; Tilapia guineensis ; Nigeria ; Port Harcourt ; brackishwater environment ; Water quality ; Fingerlings ; Chemical properties ; Physicochemical properties
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 153-157
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  • 8
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    Fisheries Society of Nigeria | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23445 | 19325 | 2018-05-02 08:32:33 | 23445 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: Spatial and temporal variations of physico-chemical variables of Onu-Iyi ?Ukwu stream were studied for 12 months from March 2005 to February 2006. Three sampling stations were established along the main stream channel from source to mouth. Spatial variation in physico-chemical parameters indicated that total alkalinity, total hardness, conductivity, and nitrate-nitrogen (NO3) recorded their highest values at the upper reaches (with values 14.0mg/l, 88.09mg/l, 17.00~kscmiscm, and 0.60mg/l respectively). Dissolved Oxygen (DO) and pH had their maximum values of 8.20mg/l and 6.94 at the middle reaches. Turbidity, biochemical oxygen demand (BOD), temperature and phosphate-phosphorus (PO4) increased steadily from source to mouth. The observed seasonal variation indicated that wet season values were higher for all the parameters except temperature, turbidity, phosphate-phosphorus (PO4) and total alkalinity although the values were not statistically significant at p〉0.05. The correlation coefficient (r) showed no significant relationships p〈0.05 between physico-chemical parameters except DO and BOD with correlation values of (0.75 and -0.54) respectively.
    Description: includes:- 2 tables.;1 fig.;17 refs.
    Keywords: Chemistry ; Limnology ; Nigeria ; Onu-Iyi-Uku Stream ; freshwater environment ; Physicochemical properties ; Phosphates ; Phosphorus ; Turbidity
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 174-180
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  • 9
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    Fisheries Society of Nigeria | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23449 | 19325 | 2018-05-02 08:39:20 | 23449 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: The physico-chemical parameters of Bosso Dam were analyzed weekly for a period of six (6) weeks from 29th October, 2009. In all, six (6) stations were identified within the dam. The physico-chemical parameters assessed were: temperature, dissolved oxygen, pH, alkalinity, hardness, conductivity and transparency. The results obtained from the analysis revealed slight variations in most parameters. There was no significant difference p〉0.05 in pH regardless of stations and weeks. But significant difference p〉0.05 were observed in dissolved oxygen, nitrate, temperature, conductivity, hardness, alkalinity, biological oxygen demand, transparency, in respect regard to stations. These variations could be due to influx of organic waste from surface run offs and inorganic waste deposited by man. The physico-chemical parameters observed, indicated that most of them fall with the recommended range or standard by the Federal Ministry of Environment
    Description: Includes:- 2 tables.;10 figs.;18 refs.
    Keywords: Chemistry ; Limnology ; Nigeria ; Bosso dam ; freshwater environment ; Physicochemical properties ; Chemical properties ; Physical properties ; Water properties
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 196-214
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  • 10
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24590 | 19325 | 2018-05-20 16:05:58 | 24590 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: The water analysis of five selected ponds in Ado-Ekiti in Ekiti State, was carried out to determine their suitability for fish culture. Pa rameters analyzed were: Temperature, Turbidity, Carbon (IV) oxide, Alkalinity, Hardness, pH and Dissolved oxygen. Values for temperature ranged between 20.0~'C and 29.0~'C, Turbidity values were between 46.0-50.2cm, Carbon (IV) oxide: 11.5-12.2mg/litre; alkalinity: 100-120mg/liter; hardness: 110-200mg/litre; pH: 6.8-7.8 and dissolved oxygen: 5.8-6.8mg/liter. The values obtained were found to be within acceptable range for fish production.
    Description: Includes: 10 references.
    Keywords: Aquaculture ; Chemistry ; Nigeria ; Physico-chemical parameter ; Fish pond ; Ado-Ekiti ; Fish production ; freshwater environment ; automation
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 97-100
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  • 11
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24618 | 19325 | 2018-05-22 06:12:36 | 24618 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: One of the priority research projects of the Nigerian Institute for Oceanography and Marine Research (NIOMR) is broodstock development and mass propagation of silver catfish, Chrysichthys nigrodigitatus of which the broodstock is naturally abundant in New Gala River. Selected physical characteristics and water physico-chemical parameters of the upper reach of the New Calabar River at Aluu were investigated. The highest depth value of 9.20 m was recorded in the middle of the river. The width of the river measured during spring high tide and low tide were 174 m and 110 m respectively. The cross-sectional area and average flow velocity of the river were 797.13 m2 and 0.374 m/s respectively. The discharge of the river was computed as 298.13m3/s. The river water was acidic most of the period (Hydrogen ion concentration, pH: 5.12 to 7.43), with low total alkalinity values (4.00 to 12.00 mgCaCO3/L) and low total hardness values (11.5 to 51.2 mgCaCO3/L) which indicate that the river water is black and soft. There was significant (p~,0.05) seasonal variation in temperature (23.1 to 31.7~'C\}, Secchi transparency (9.30 to 19.00 cm), total hardness (11.5 to 51.2 mgCaCO3/L), dissolved oxygen (5.20 to 7.50 mg/L) and dissolved oxygen deficit (0.02 to 2.95mg/L). These results are useful for several stake holders who use the river as a sink for trade wastes, as source of water for fish farming, as source of broodstocks of Chrysichthys nigrodigitatus, as raw water for water treatment plants, and as means of transportation of industrial materials.
    Description: Includes: 16 references.
    Keywords: Chemistry ; Fisheries ; Limnology ; Chrysichthys nigrodigitatus ; Nigeria ; New Calabar River ; New calabar River ; Physical characteristics and physico-chemical features ; Seasonal variation ; freshwater environment ; automation
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 206-210
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  • 12
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24619 | 19325 | 2018-05-22 06:14:16 | 24619 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Eight month physicochemical study of Dadin Kowa Dam was carried out forthnightly from July, 2011 to february 2012. Air temperature ranged from 18.25~'C ~c 28~'C ~c 0.50 to 28~'C ~c 2.16. Water tmperature ranged from 18.75~'C ~c 2.21. Transparency ranged from 11.00cm ~c 1.83 to 29.63 cm ~c ~c 2.14. Conductivity ranged from 13.00~Ks/cm ~c 13.33 to 41.38~Ks/cm ~c 5.54. Hydrogen ion (pH) ranged from 6.69 ~c 1.03 to 8.39 ~c 1.17. Dissolved oxygen ranged from 6.39mg/l ~c 1.03 to 10.14mg/l ~c 1.17. Total alkalinity ranged from o.69mg/l ~c 0.38 1.34mb/l ~c 0.02. Total ammonia ranged from 0.20mg/l ~c 0.027 to 0.83mg/l ~c 0.05. There were various levels of correlation between these parameters. There was no significant difference between both sites and months (p〉0.05) of all the parameters except total nitrogen which show a significant difference between the sites (p〈0.05) and transparency also shows a significance between the months (p〈0.05). All physicochemical parameters were almost within the tolerable limits for supporting aquatic life.
    Description: Includes: 27 references.
    Keywords: Fisheries ; Chemistry ; Nigeria ; Dadin Kowa Dam ; Physico-chemical parameters ; Fish production ; Dadin Kowa Dam ; freshwater environment ; automation
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 211-213
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  • 13
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    Islamic Azad University, Science and Research Branch, Tehran, Marine Biology
    In:  http://aquaticcommons.org/id/eprint/19419 | 17408 | 2016-01-22 09:16:53 | 19419 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-06-28
    Description: In the present research, investigations were carried out for structure elucidation of natural compounds and also for studing biological and teratogenical effects of two Genus of soft corals named as " Echinogorgia cf. indica" and "Sinularia erecta" in Persian Gulf. First, 350 gr Echinogorgia was extracted by Acetone, then, the extract was separated by ether from aqueos phase to give 4.5 gr oil. The oil eluted with Petrol - ether Et2 o (9:1) which was recovered Linderazulene and it's derivative as purple Cristals (350 mg/ca 0.1 %). In order to determine molecular structure, the Samples were used for spectroscopic method as: H1- NMR , C13- NMR and 2D NMR. Also, for extraction and structure elucidation of natural compounds, the soft coral " sinularia erecta " were used 1187/37 gr and extracted by Aceton. The extract was concentrated and resulting aqueous suspension and extracted by using ether to give 8.41 gr oil. The oil , was Chromatographed on a column of silica gel and some different fractions were gathered. Initial fraction (1-11) which were nonpolar compounds were seprated by GC/MS. Mass spectrum were prepared and much compounds were recognized.
    Description: PhD
    Description: Advisors:Sh. Oryan, Ab. Rustaiyan Counsellors:K. Parivar, K. Zareh. The full text document is in Farsi only so it has not been possible for AC Editors to check the metadata input.
    Keywords: Biology ; Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
    Format: application/pdf
    Format: application/pdf
    Format: 237
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  • 14
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    Fisheries Society of Nigeria | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23460 | 19325 | 2018-05-05 12:31:34 | 23460 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: The morphometric characters of Cynothrissa mento from three major Lagoons (Ologe, Badagry and Epe) in Lagos, Nigeria were compared to assess the possibility of this fish species from the three Lagoons belonging to the same sub-population. The length-weight relationships (LWR), and condition factors (CF) of the fish were also described as well as the physico-chemical parameters of the three water bodies. The study was conducted between May, 2009 and April, 2010 and monthly sampling of fish and water was done in each sampling site. Seven7 physico-chemical parameters were assessed and these are; temperature, pH, salinity, turbidity, dissolved oxygen, total alkalinity and total hardness. A total of 294 specimens (Ologe 60, Badagry 174 and Epe 60) of C. mento were collected from the landings of the local fisher folks from the sampling sites. Seven morphometric characters; total length (TL), standard length (SL), body depth (BD), head length (HL), head depth (HD), eye diameter (ED) and interorbital width (IW) were measured. There was no significant difference (p 〉 0.05) in all the physico-chemical parameters measured among the sampling sites except pH. Coefficient of difference revealed that the C. mento from the three lagoons are uniform in all the morphometric parameters examined, which means that the specimens from the three sampling sites do not belong to different sub-populations. The growth coefficient/slope (b) values obtained for the fish species from the sampling sites ranged from 2.27 - 2.53, and differed significantly (p 〈 0.05) from 3, which indicates that most of the fish species have negative algometric growth.
    Description: Includes:- 4 tables.;1 fig.;24 refs.
    Keywords: Ecology ; Chemistry ; Cynothrissa mento ; Nigeria ; Ologe Lagoon ; Nigeria ; Badagry Lagoon ; Nigeria Epe Lagoon ; marine environment ; Population dynamics ; Morphometry ; Check lists ; Length-weight relationships ; Condition factor ; Physicochemical properties
    Repository Name: AquaDocs
    Type: conference_item , TRUE
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  • 15
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24638 | 19325 | 2018-05-24 09:36:38 | 24638 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Study of some Physico-chemical parameters and fish species composition of Doma Darn was carried out between the month of August 2012. Fishing communities along the dam were selected at sampling stations and collection of fish species. The values of physico-parameters obtained for stations were in the range of 28.10-92 m for depth, 27.70-28.48~'for temperature, 7.03-7.64 for PH, 7.23-7.64mg/l for dissolved oxygen (DO), 30.08-31.75 ntu for turbidity, 94.64-105.17mg/l for alkalinity and 79.17-80.58mg/l for total hardness. The result indicated that there was significant difference (p〈0.5)for depth, temperature turbidity and alkalinity, while there was no significant difference (p〈0.05) for DO, pH and water hardness among the stations. The result of these parameters among the duration shows that there was significant different (p〈0.05) in all the parameters except pH. The study revealed that there were twenty-five (25) fish species belonging to 12 families in the dam. The family Cichlidae and Mochokidae and Bagridae which has three each, While the family, Polypteridae, Channidae, Centropomidae, flepsetidae and Protopteridae has the lowest number of one (1) each. The overall result revealed that the Phvsico-chemical parameters were mostly influenced by duration and not much by stations; and parametersoaram measured were within the recommended water quality requirement for growth and survival of aquatic organisms.
    Description: Includes: 10 references.
    Keywords: Chemistry ; Fisheries ; Nigeria ; Doma Dam ; Doma Dam ; Fishing community ; Physico-chemical parameter ; Fish species ; freshwater environment ; automation
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    Type: conference_item , TRUE
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  • 16
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    Islamic Azad University, Science and Research Branch, Tehran, Marine Biology
    In:  http://aquaticcommons.org/id/eprint/19122 | 17408 | 2015-12-11 10:34:52 | 19122 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: Green scat namely as Scatophagus argus argus is a venomous aquarium fish belonging to Scatophagidae family. It can induce painful wounds in injured hand with partial paralysis to whom that touch the spines. Dorsal and ventral rough spines contain cells that produce venom with toxic activities. According to unpublished data collected from local hospitals in southern coastal region of Iran, S. argus is reported as a venomous fish. Envenomation induces clinical symptoms such as local pain, partial paralysis, erythema and itching. In the present study green scat (spotted scat) was collected from Persian Gulf coastal waters. SDS-PAGE indicated 12 distinct bands in the venom ranged between 10-250 KDa. The crude venom had hemolytic activity on human erythrocytes (1%) with an LC100 (Lytic Concentration) of about 1.7 μg. The crude venom can release 813 μg proteins from 0.5% casein. Phospholipase C activity was recorded at 3.125 μg of total venom. Our findings showed that the edematic activity remained over 48 h after injection.The purification of the venom was done by HPLC and 30 peaks were obtained within 80 min but only one peak in 68 min retention time showed hemolytic activity at 90% acetonitril was isolated. The area percentage of the hemolytic protein showed that this hemolytic protein consist of 32 percent of total proteins and its molecular weight was 72 KDa in SDS_PAGE.The results demonstrated that crude venom extracted from Iranian coastal border has different toxic and enzymatic activities.
    Description: PhD
    Description: Advisors:Shahla Jamili, Delavar Shahbazzadeh. Counsellors: Mohammad reza Fatemi, Behrouz Vaziri
    Keywords: Biology ; Chemistry ; Fisheries
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    Type: thesis
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    Islamic Azad University, Science and Research Branch, Tehran, Marine Biology
    In:  http://aquaticcommons.org/id/eprint/19197 | 17408 | 2016-02-07 16:50:51 | 19197 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: Chemical ecology is the science of study and analysis of natural chemical products in result of biochemical processes in organisms and their reactions to variations of ecological and environmental parameters.In marine chemical ecology the existence of natural products in aquatic organisms and their ecological roles in marine animals and their reactions to environmental parameters variations will be studied.Among them, fatty acids are the most various and abundant ones in natural products which had been extracted from many marine organisms such as mollusks and algae.In this study selected animals were the dominant species of mollusks in intertidal zone of chabahar bay including gastropods, bivalves and polyplacophora classes.Nerita textilis and Turbo coronatus species are among gastropoda, Saccostrea cucullata is from bivalve, and Chiton lamyi is from polyplacophora.After seasonal sampling, separation and identification of natural products of these species, fatty acids had been isolated and identified by GC mass chromatography and their seasonal variations had been identified.In addition environmental factors of the location including pH, salinity temperature, dissolved oxygen, chlorophyll a and nutrients were measured monthly.Then the effect of seasonal variations of environmental factors on fatty acids had been studied by applying statistical analysis.GC/MS resulted thirteen fatty acids, which the most importants were myristic, stearic, oleic, palmitoleic, arachidonic and eicosapentaenoic acids.In majority of species palmitic acid was most abundant than the others and saturatedes had the most percentage levels than unsaturated ones.Although seasonal variations of identified fatty acids was not similar in species, but the majority of unsaturated ones had their maximum during winter, while saturated acids reached their maximum in summer.Statistical Analysis showed the strong correlations between Environmental factors and some fatty acids and temperature, nitrate, silicate and pH had strong correlations in all species.The species was studied from the point of lipid content and the results showed a good quality of lipid content in the selected species in the intertidal zone of Chabahar bay.
    Description: PhD
    Description: Advisors:Peiman Eghtesadi, Ali Mashianchin Counsellors:Isa Iavari, Shahla Jamili. The full text document is in Farsi only so it has not been possible for AC Editors to check the metadata input.
    Keywords: Biology ; Chemistry ; Ecology
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  • 18
    Electronic Resource
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    Journal of Chemometrics 5 (1991), S. 545-545 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 19
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    Journal of Chemometrics 6 (1992) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    ISSN: 0886-9383
    Keywords: Derivatization reaction ; Factorial design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of nucleophiles have been successfully identified and quantified using the Kröhnke reaction with 2,3-diphenyl derivatives of quinolizinium salts. Optimization of the reaction conditions by means of a mathematical model involving analysis of the response surface has led to a better understanding of the factors exerting an influence on the above reaction.The parameters chosen were temperature, reaction time, base concentration, water concentration and nucleophile concentration. The reaction was developed in polar aprotic solvents (acetone, acetonitrile). To facilitate the nucleophilic attack, the presence of an organic base (triethylamine) was necessary, although concentrations in excess of 0·15M did not alter the development of the reaction. Since pharmaceutical solutions are often aqueous, the influence of water on the reaction was studied. Low water volumes have no significant influence on the opening of the quinolizinium ring by the nucleophilic reagent. However, when the water proportion exceeded that of the organic solvent, the fluorescence intensity was lower than expected. Development of the fluorescent reaction product was first detected 5 min after the reaction started. The fluorescence intensity reached its optimum value after 138 min.
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  • 21
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    Journal of Chemometrics 6 (1992), S. i 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 22
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    Journal of Chemometrics 6 (1992), S. 65-83 
    ISSN: 0886-9383
    Keywords: Trilinear decomposition ; Receptor modeling ; Source identification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In many cases, monitoring data for ambient airborne particles can be organized in the form of a three-way data table with one way for chemical species, one for sampling periods and one for sites. A direct trilinear decomposition followed by a matrix reconstruction (DTDMR) is developed to analyze such a data table as a whole. The three-way data set is composed into three two-way matrices by a direct trilinear decomposition (DTD). The column vectors of each of the matrices are called ‘source profiles’, ‘emission patterns’ and ‘site coefficients’ respectively. Particulate sources are identified by examining both their source profiles and emission patterns. After the sources have been identified, emission patterns and site coefficients are used to produce a three-way matrix that gives estimates of mass contributions of sources to the samples collected at every site in every period. By simulation study, not only has the method been verified, but a good indicator has been found that shows the number of factors (i.e. sources) in the system. Unlike other receptor models, DTDMR does not require source profile data and does not involve trial-and-error procedures. Since DTDMR identifies sources based on variations in two dimensions, it has a higher potential to distinguish two sources that have similar chemical compositions. The DTDMR model has provided excellent results with simulated data and has been applied in a real world three-way data set.
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  • 23
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    Journal of Chemometrics 6 (1992), S. 163-175 
    ISSN: 0886-9383
    Keywords: Multiple-correspondence analysis ; Starch granule description ; Image analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raw starch is composed botanically of characteristic granules of various sizes and shapes, so that each kind of starch may be characterized by the population of its granules. In the present study ten commercial starch species were studied: wheat, rice, manioc, potato, arrowroot, amylomaize, normal maize, waxy maize and two different banana species. Six variables measuring the size and shape of granules were obtained by image analysis. The objective was to find a method to describe and compare the granule populations of the ten species. For such a study, multiple-correspondence analysis (MCA) was applied. MCA makes it possible to draw similarity maps of categories and objects. For each starch species the frequency distributions (histograms) of the six variables were assessed and each granule was characterized by its species and the classes of histograms to which it belonged. MCA was applied to the granule table and a description of the histogram classes and the granules was obtained. From the variables description a general typology of the granules was deduced. The similarity maps showed considerable scatter of the granules for all species except rice. A particular species could therefore not be identified by a single granule, but the granule distribution seemed to be characteristic. MCA was an appropriate method to analyse these data because it points out non-linear relationships between quantitative and qualitative variables.
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  • 24
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    Journal of Chemometrics 6 (1992), S. 177-188 
    ISSN: 0886-9383
    Keywords: PLS ; Prediction error ; Background constituents ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modification of a technique proposed by Lorber and Kowalski for the estimation of prediction errors is presented. The method is applied to five data sets. The results show that for some data sets the estimated prediction errors are close to the actual prediction errors for samples within the calibration range, while samples outside the calibration range must be background corrected before quantification of the prediction error.
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  • 25
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    Journal of Chemometrics 6 (1992), S. 199-216 
    ISSN: 0886-9383
    Keywords: MARS ; Splines ; Multivariate calibration ; Non-linear ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This tutorial paper presents a simplified view of one of the more recently published multivariate calibration methods particularly suited to dealing with non-linear data sets. The method is referred to as MARS and stands for multivariate adaptive regression splines. Simple examples are provided to explain the workings of the method.
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  • 26
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    Journal of Chemometrics 4 (1990), S. 47-50 
    ISSN: 0886-9383
    Keywords: Classification ; Pattern recognition ; Preprocessing ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Over the past 15 years the linear learning machine has been applied to a large number of chemical problems. The learning machine approach is conceptually simple and does not require knowledge about the statistical distribution of the data. However, there are problems associated with this approach. One problem which has not been investigated is the influence of mislabeled samples on the positioning of the hyperplane in feature space. If a few samples in a data set are incorrectly tagged prior to training (i.e. the samples are labeled as members of class 2 even though they are actually members of class 1), it is still possible using the linear learning machine to achieve a classification success rate of 100% for the training set. However, unfavorable results will be obtained for the prediction set. The magnitude of this effect and its potential implications regarding the proper use of the linear learning machine are discussed.
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  • 27
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    Journal of Chemometrics 4 (1990), S. 51-59 
    ISSN: 0886-9383
    Keywords: Deconvolution ; Jansson's method ; Peak restoration ; Iterative deconvolution ; Peak resolution ; Non-linear deconvolution ; Super-resolution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In previous papers Jansson's method was found to be successful at deconvolving severely overlapped gas chromatographic peaks. In the most recent paper the method was evaluated with respect to quantitative accuracy, peak area and retention time repeatability. The problems associated with deconvolving noisy data and some alternatives which can improve the ability of Jansson's method to deconvolve noisy data are discussed. These alternatives include presmoothing the data with a nine-point, third-order polynomial filter and data reblurring. This paper will test these methods on peaks with various degrees of resolution and signal-to-noise ratios.
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  • 28
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    Journal of Chemometrics 4 (1990), S. 61-77 
    ISSN: 0886-9383
    Keywords: Infrared ; Spectroscopy ; Spectrometry ; Retrieval ; Confirmation ; Chemometrics ; Adequate peaks ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the series of analytical techniques for identification of chemical substances, infrared spectrometry presents by far the highest information content. However, the information is most complicated too. It concerns a multitude of band positions, band intensities and band shapes, which, moreover, can be disturbed by matrix and other effects. The high redundancy, however, allows conclusions to be made by a qualitative, subjective procedure.IR is often used to prove the equality between a sample and a reference material, e.g. in quality control of a production process. In forensic control, the question to be answered is mostly not to prove equality, but whether or not the presence of a compound in a sample, e.g. a drug, can be proved. Moreover, testing has to be performed according to objective rules.To fulfil these requirements, a new retrieval algorithm, the ‘Adequate Peaks Search’, is presented. It concerns representing the reference spectra by sets of adequate peak positions and the sample spectrum by a set of all peak positions, whereafter the cross-sections of the sample set and the reference sets are determined. The concept ‘adequate peak’ is defined and criteria have been formulated to evaluate the results into a positive (presence of the analyte is proved) or negative (presence is not proved) conclusion.The detection limit when the Adequate Peaks Search (APS) method was applied was four to seven times lower than that attained by a number of experts.
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  • 29
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    Journal of Chemometrics 4 (1990), S. 79-90 
    ISSN: 0886-9383
    Keywords: PLS ; Three-way matrices ; Calibration ; Residual bilinearization ; Background correction ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When using hyphenated methods in analytical chemistry, the data obtained for each sample are given as a matrix. When a regression equation is set up between an unknown sample (a matrix) and a calibration set (a stack of matrices), the residual is a matrix R.The regression equation is usually solved by minimizing the sum of squares of R. If the sample contains some constituent not calibrated for, this approach is not valid. In this paper an algorithm is presented which partitions R into one matrix of low rank corresponding to the unknown constituents, and one random noise matrix to which the least squares restrictions are applied. Properties and possible applications of the algorithm are also discussed.In Part 2 of this work an example from HPLC with diode array detection is presented and the results are compared with generalized rank annihilation factor analysis (GRAFA).
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    Journal of Chemometrics 4 (1990), S. 91-96 
    ISSN: 0886-9383
    Keywords: Sample size ; Monte Carlo ; Multivariate, normal ; Q-Q plots ; Classification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Because many pattern recognition techniques are predicated on the assumption of mutivariate normal data, Monte Carlo simulation studies were performed to determine the number of samples that are necessary to describe a multivariate normal population adequately. From these studies we have learned that hundreds of samples are required. These results suggest that parametric procedures should only be used to analyze very large data sets.
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    Journal of Chemometrics 4 (1990), S. 97-100 
    ISSN: 0886-9383
    Keywords: Matrix decomposition ; NIPALS ; Principal component ; SIMCA ; PLS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Non-linear Iterative Partial Least Squares (NIPALS) algorithm is used in principal component analysis to decompose a data matrix into score vectors and eigenvectors (loading vectors) plus a residual matrix. NIPALS starts with some guessed starting vector. The principal components obtained by NIPALS depends on the starting vector; the first principal component could not always be computed. Wold has suggested a starting vector for NIPALS, but we have found that even if this starting vector is used, the first principal component cannot be obtained in all cases. The reason why such a situation occurs is explained by the power method. A simple modification of the original NIPALS procedure to avoid getting smaller eigenvalues is presented.
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    Journal of Chemometrics 4 (1990), S. 101-101 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 4 (1990), S. 102-102 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 4 (1990) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 4 (1990), S. 102-102 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 4 (1990), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 4 (1990), S. 103-121 
    ISSN: 0886-9383
    Keywords: Kalman filter ; Recursive digital filter ; Square-root filter ; Information filter ; Parameter estimation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of recursive filtering techniques for parameter estimation in a variety of areas is reviewed. In particular, the Kalman filter algorithm is described, along with several variations, including square-root, UDUT and information filters. The solution to parameter estimation problems is discussed for both linear and non-linear models. Applications described include calibration, curve resolution in spectroscopy, chromatography, electrochemistry, kinetic analysis and process monitoring.
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    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 7 (1993), S. 243-253 
    ISSN: 0886-9383
    Keywords: Orthogonal expansion ; Mapping ; Modelling ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we discuss the orthogonal expansion of data matrices and its application to mapping and modelling. Two new methods, modified optimal discriminant plane (MODP) for mapping and order Gram-Schmidt orthogonalization (OGSO) for modelling, are proposed and examples are given.
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    Journal of Chemometrics 7 (1993) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
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  • 41
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    Journal of Chemometrics 7 (1993), S. 381-392 
    ISSN: 0886-9383
    Keywords: Factor analysis ; Kolmogorov-Smirnov test ; Non-parametric tests in factor analysis ; Non-parametric test for principal components ; Principal component analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Each eigenvector of the dispersion matrix [X]T [X] was shown to be a partial predictor of the original data matrix [X], the sum of the predictions from the individual principal components being equal to the expectance of [X]. By comparing the distributions of the members of two neighbouring predicted matrices, [X̃]1…i and [X̃]1…i+1 (i.e. the sums of the first i and i + 1 individual predictions respectively), it was shown that they should be indistinguishable provided that i is equal to or greater than the effective rank of [X], and significantly different otherwise. This was confirmed by analysing the visible absorption spectra of methyl orange and methyl red solutions as well as the Raman spectra of Na2SO4 and MgSO4 solutions. On the grounds of these findings, a non-parametric goodness-of-fit test for assessing the effective rank of [X] was proposed which proved to be comparatively conservative and more robust than most currently used tests.
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    Journal of Chemometrics 7 (1993), S. 447-452 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 7 (1993), S. 477-494 
    ISSN: 0886-9383
    Keywords: Three-way principal components analysis ; Core matrix ; Body diagonalization ; Lower and upper bounds ; Simulation ; Soil contamination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In contrast with conventional PCA, a direct superposition and joint interpretation of loading plots is not possible in three-way PCA, since there may be data variance which is described by unequal components of different modes. The contributions to variance of all possible combinations of components are described in the core matrix. Body diagonalization, which is achieved by appropriate rotation of component matrices, is an essential tool for simplifying the core matrix structure. The maximum degree of body diagonality which may be obtained from such transformations is analysed from both the mathematical and simulation viewpoints. It is shown that, at least in the average case, high degrees can be expected, which makes the procedure reasonable for many practical applications. Furthermore, simulation as well as theoretical derivation show that the success of body diagonality depends on the so-called polarity of the core array. The methodology is illustrated by a three-way data example from environmental chemistry.
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  • 44
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    Journal of Chemometrics 7 (1993) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
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  • 45
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    Journal of Chemometrics 7 (1993), S. 495-526 
    ISSN: 0886-9383
    Keywords: Standard errors ; Eigenvalues ; PCA ; MLR ; GRAM ; Rank estimation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New expressions are derived for the standard errors in the eigenvalues of a cross-product matrix by the method of error propagation. Cross-product matrices frequently arise in multivariate data analysis, especially in principal component analysis (PCA). The derived standard errors account for the variability in the data as a result of measurement noise and are therefore essentially different from the standard errors developed in multivariate statistics. Those standard errors were derived in order to account for the finite number of observations on a fixed number of variables, the so-called sampling error. They can be used for making inferences about the population eigenvalues. Making inferences about the population eigenvalues is often not the purposes of PCA in physical sciences. This is particularly true if the measurements are performed on an analytical instrument that produces two-dimensional arrays for one chemical sample: the rows and columns of such a data matrix cannot be identified with observations on variables at all. However, PCA can still be used as a general data reduction technique, but now the effect of measurement noise on the standard errors in the eigenvalues has to be considered. The consequences for significance testing of the eigenvalues as well as the usefulness for error estimates for scores and loadings of PCA, multiple linear regression (MLR) and the generalized rank annihilation method (GRAM) are discussed. The adequacy of the derived expressions is tested by Monte Carlo simulations.
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  • 46
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    Journal of Chemometrics 7 (1993), S. 559-566 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
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  • 47
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    Journal of Chemometrics 8 (1994), S. 21-36 
    ISSN: 0886-9383
    Keywords: GRAM ; Tucker ; Unfold ; NBRA ; Second-order ; Three-way ; PARAFAC ; Trilinear ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If an analytical instrument or instrumental method gives a response matrix when analyzing a pure analyte, the instrument or instrumental method is called a second-order method. Second-order methods that generate a response matrix for a pure analyte of rank one are called rank-one second-order methods. If the response matrix of a pure analyte is not rank one, essentially two cases exist: medium rank (between two and five) and high rank (greater than five). Subsequently, medium- and high-rank second-order calibration tries to use medium- and high-rank second-order methods to analyze for analytes of interest in a mixture. A particular advantage of second-order methods is the ability to analyze for analytes of interest in a mixture which contains unknown interferences. Keeping this advantage is the challenge on moving away from rank-one second-order calibration methods. In this paper a medium-rank second-order calibration method is proposed based on least-squares restricted Tucker models. With this method the second-order advantage is retained.
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  • 48
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    Journal of Chemometrics 8 (1994), S. 81-93 
    ISSN: 0886-9383
    Keywords: Sensory evaluation ; Cumulative ranks ; Assessor variation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A graphical method of assessing differences between sets of rankings based on cumulative ranks is developed. The method can be used to identify rankings that differ over all or just part of the range of objects ranked. The method is applied to an example of sensory evaluation of green peas in which ten assessors scored six attributes on each of 60 samples.
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  • 49
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    Journal of Chemometrics 8 (1994), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 50
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    Journal of Chemometrics 8 (1994), S. 155-168 
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    Keywords: Trilinear models ; Tensorial resolution ; PARAFAC ; Swamps ; Two-factor degeneracy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The alternating least squares PARAFAC algorithm is a useful tool for resolving trilinear three-way data arrays. Occasionally, however, it becomes bogged down for many iterations in the vicinity of a poor quality resolution before moving on to a much superior optimum fit. We investigate this behavior in a simulation study and suggest ways of overcoming the obstacles it presents.
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  • 51
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 8 (1994), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 53
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    Journal of Chemometrics 8 (1994), S. 181-203 
    ISSN: 0886-9383
    Keywords: RAFA ; GRAM ; Eigenvalues ; Bias ; Variance ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rank annihilation factor analysis (RAFA) is a method for multicomponent calibration using two data matrices simultaneously, one for the unknown and one for the calibration sample. In its most general form, the generalized rank annihilation method (GRAM), an eigenvalue problem has to be solved. In this second paper expressions are derived for predicting the bias and variance in the eigenvalues of GRAM. These expressions are built on the analogies between a reformulation of the eigenvalue problem and the prediction equations of univariate and multivariate calibration. The error analysis will also be performed for Lorber's formulation of RAFA. It will be demonstrated that, depending on the size of the eigenvalue, large differences in performance must be expected. A bias correction technique is proposed that effectively eliminates the bias if the error in the bias estimate is not too large. The derived expressions are evaluated by Monte Carlo simulations. It is shown that the predictions are satisfactory up to the limit of detection. The results are not sensitive to an incorrect choice of the dimension of the factor space.
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    Journal of Chemometrics 4 (1990), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 55
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    Journal of Chemometrics 4 (1990), S. 337-354 
    ISSN: 0886-9383
    Keywords: Chemometrics ; Chemometrics Society ; History of chemometrics ; Pioneers of modern chemometrics ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This is a first foray into the historical start and early years of chemometrics from about 1972 onwards. We have gathered interviews with three originators (Kowalski, Wold and Massart) as well as with a selected group of six other well-known chemometricians who gradually became active in the 1970s (Christie, Clementi, Hopke, Martens, Brown and Deming). The interviews include amongst a host of subjective recollections a succinct record of the key historical literature as highlighted by the interviewees' own rankings of ‘earliest’ and ‘best’.A discussion of the most general commonalities in these interviews together with other historical material is presented in the second part of the paper.
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    Journal of Chemometrics 4 (1990), S. 355-360 
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    Keywords: Pattern recognition ; U.K. chemometrics usage ; Quantitative structure-activity relationships ; Artificial intelligence ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A survey of members of the U.K. QSAR Discussion Group has been made to determine the extent of use and development of chemometric and artificial intelligence (AI) methods in the analysis of multivariate quantitative structure-activity relationship (QSAR) data in the U.K. Chemometric methods were found to be well established in both industrial and educational establishments and there was significant method development occurring. AI methods were not employed to any great extent and the general level of interest in these techniques was low compared to chemometric methods. A requirement for more education in multivariate statistical methods and regression methods was indicated. A need for a user-friendly, comprehensive, commercially available multivariate statistical package containing multivariate stability testing and regression diagnostic methods was identified.
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    Journal of Chemometrics 4 (1990), S. 361-377 
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    Keywords: Abstract factor analysis ; Exploratory data analysis ; Principal components ; Simulated equilibria ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract factor analyses were performed on databases consisting of simulated samples from aqueous equilbria. The program COMPLEX was used to generate equilibrium species in a system of three reactant metals and five reactant bases. Reactant concentrations and pH were drawn from random-normal distributions so that sample data vectors comprised a multivariate log-normal distribution of equilibrium concentrations. In addition, sample groups were created containing different distributions for pH and reactant concentrations.Equilibrium species were shown to contain variance contributed by change in pH among samples as well as change in reactant concentrations. Factor modelling revealed the qualitative relationships among the species and how the relationships change with pH. Factors also revealed those reactants containing variance in the data matrix. In some cases, reactant variance obscured relationships between pH and the equilibrium species.Since factor modelling of a simulated data matrix revealed the expected chemical equilibrium interactions, a potentially powerful tool exists for investigating the effects of outliers and error.
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    Journal of Chemometrics 8 (1994), S. 301-302 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 8 (1994) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 8 (1994), S. 305-331 
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    Keywords: Pyrolysis ; Mass spectroscopy ; Multivariate analysis ; Biological material identification ; Convexity ; Cones ; Subspaces ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This work addresses the classification of high-dimensional time-dependent pyrolysis mass spectra of biological samples. The aim was the detection and classification of biological agents, and the developed approach resembles mixture analysis. The data were projected on to a low-dimensional subspace using singular value decomposition. Then a convex cone was formed on this subspace, showing as its corners physically meaningful components of the sample. This technique enabled separation of a biological material signal largely independent of the absolute amount of sample. The detection of the presence of any biological material could be accomplished based on the convex cone alone, without other reference to the mass spectra. Automated clustering of samples was successfully carried out using a minimal spanning tree.
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    Journal of Chemometrics 8 (1994), S. 373-373 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 62
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    Journal of Chemometrics 4 (1990), S. 389-412 
    ISSN: 0886-9383
    Keywords: Chemometrics ; Chemometrics Society ; History of chemometrics ; Pioneers of modern chemometrics ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This is a first foray into the historical start and early years of chemometrics from about 1972 onwards. We have gathered interviews with three originators (Kowalski, Wold and Massart) as well as with a selected group of six other well-known chemometricians who gradually became active in the 1970s (Christie, Clementi, Hopke, Martens, Brown and Deming). The interviews include amongst a host of subjective recollections a succinct record of the key historical literature as highlighted by the interviewees' own rankings of ‘earliest’ and ‘best’.A discussion of the most general commonalities in these interviews together with other historical material is presented in the second part of the paper.
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  • 63
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    Keywords: Discriminant analysis ; Size-exclusion chromatography ; Wheat proteins ; Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
    Notes: Continuous digitalized signals such as spectra, electrophoregrams or chromatograms generally have a large number of data points and contain redundant information. It is therefore troublesome performing discriminant analysis without any preliminary selection of variables. A procedure for the application of canonical discriminant analysis (CDA) on this kind of data is studied. CDA can be presented as a succession of two principal component analyses (PCAs). The first is performed directly on the raw data and gives PC scores. The second is applied on the gravity centres of each qualitative group assessed on the normalized PC scores. A stepwise procedure for selection of the relevant PC scores is presented. The method has been tested on an illustrative collection of 165 size-exclusion high-performance (SE-HPLC) chromatograms of proteins of wheat belonging to 55 genotypes and grown in three locations. The discrimination of the growing locations was performed using seven to nine PC scores and gave more than 86% accurate classifications of the samples both in the training sets and the verification sets. The genotypes were also rather well identified, with more than 85% of the samples correctly classified. The studied method gives a way of assessing relevant mathematical distances between digitalized signals according to qualitative knowledge of the samples.
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  • 64
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    Keywords: Principal components ; Multiple and stepwise regression ; Non-parametric density and regression estimation ; Bootstrap inference ; Canonical correlation ; PLS regression ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A statistical study of the dependence between various critical fusion temperatures of a certain kind of coal and its chemical components is carried out. As well as using classical dependence techniques (multiple, stepwise and PLS regression, principal components, canonical correlation, etc.) together with the corresponding inference on the parameters of interest, non-parametric regression and bootstrap inference are also performed.
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    Journal of Chemometrics 9 (1995), S. 197-209 
    ISSN: 0886-9383
    Keywords: proficiency test ; true value ; homogeneity robust statistic ; standard ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Profficiency tests raise two types of problems: (i) the homogeneity of a sample must be carefully checked before using it as a reference material; (ii) it is necessary to define a conventional reference value (RV) in order to rank participants. Since these topics are poorly addressed in the literature, a reference material was specially prepared in order to propose a procedure for verifying homogeneity and to establish whether the algorithms classically used to compute the conventional true value have an influence on the conclusion of the test.The homogeneity of the sample was not perfect and univariate and multivariate techniques were used to demonstrate some analytes can be suspected as heterogeneous. However, this was considered adequate for introducing the sample in a large proficiency test organized between four laboratory associations which regularly perform such tests. Altogether more than 3000 measurements were collected and eight algorithms were applied to compute the RV on 14 analytes. Thus is was possible to demonstrate that some of these algorithms are better adapted than others. It is also obvious that some analytes are better suited to proficiency testing.It can be concluded from this work that some effort towards standardization would be profitable to check homogeneity or to compute the RV, especially since the economic weight of proficiency testing is becoming even more important with the development of certification accreditation.
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    Journal of Chemometrics 5 (1991), S. 129-145 
    ISSN: 0886-9383
    Keywords: Multivariate calibration ; Biased regression ; Partial least squares (PLS) ; Principal component regression (PCR) ; Model validation ; Non-linear calibration ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With the goal of understanding global chemical processes, environmental chemists have some of the most complex sample analysis problems. Multivariate calibration is a tool that can be applied successfully in many situations where traditional univariate analyses cannot. The purpose of this paper is to review multivariate calibration, with an emphasis being placed on the developments in recent years. The inverse and classical models are discussed briefly, with the main emphasis on the biased calibration methods. Principal component regression (PCR) and partial least squares (PLS) are discussed, along with methods for quantitative and qualitative validation of the calibration models. Non-linear PCR, non-linear PLS and locally weighted regression are presented as calibration methods for non-linear data. Finally, calibration techniques using a matrix of data per sample (second-order calibration) are discussed briefly.
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    Journal of Chemometrics 5 (1991), S. 147-161 
    ISSN: 0886-9383
    Keywords: Digital filtering ; Real-time analysis ; Kalman filtering ; Infrared spectroscopy ; Principal components regression ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Real-time monitoring of pollutant levels from a mobile measuring platform requires fast, flexible data analysis methods. This paper reports a method for rapid analysis of passive remotely sensed infrared data with the aid of a Kalman filter. The background spectra produced by emission from the atmosphere are modelled at the start of the data collection sequence with a simple principal components model obtained by eigenanalysis of the initial ‘blank’ data taken with the spectrometer. The species of interest are included in the state space model by a separate measurement of their infrared spectra. It is demonstrated that for best filter performance in detecting the simulated pollutant species SF6 in the atmosphere, a filter model with two principal components describing the emission background works best. The filter ‘maps’ of SF6 closely follow the integrated spectral intensities measured after removal of suitable backgrounds.
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    Journal of Chemometrics 5 (1991), S. 163-179 
    ISSN: 0886-9383
    Keywords: Principal component analysis ; Factor analysis ; Chemometrics ; Exploratory data analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Principal component analysis is used to examine large multivariate databases. The graphical approach to exploratory data analysis is described and illustrated with a single example of chemical composition data obtained on environmental dust particles. While the graphical approach to exploratory data analysis has certain advantages over the numerical procedures, the empirical approach described here should be viewed as complementary to the more robust treatments that statistical methodologies afford.
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    Journal of Chemometrics 5 (1991), S. 181-192 
    ISSN: 0886-9383
    Keywords: Chemometrics ; Systems theory ; Experimental design ; Multivariate analysis ; Measurement science ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemometrics is defined as the application of mathematical and statistical methods to chemical systems. Systems theory is seen to be useful for organizing and categorizing the inputs to and outputs from chemical systems. Advances in measurement science in the 1950s and 1960s, particularly in analytical chemistry, created a need for a multivariate approach to data analysis. Early chemometrics emphasized the use of structure-finding methods for existing data sets. In many instances, data sets can be obtained from designed experiments. Such data sets are more likely to contain the desired information and the data can usually be acquired at less cost. Renewed interest in statistical process control will provide many new, more robust data sets in the future.
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    Journal of Chemometrics 5 (1991), S. 193-199 
    ISSN: 0886-9383
    Keywords: Kalman filter ; Chemometrics ; 5-Br-PADAP ; Metallic ions ; Simultaneous spectrophotometric determination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes the simultaneous determination of cobalt, nickel, copper, zinc and cadmium by spectrophotometry and the Kalman filter method. Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) react with 5-bromo-2-(2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) in the presence of cationic surfactant cetyl pyridinium bromide (CPB) to form five different coloured ternary complexes. The absorption curves of these complexes overlap severely in the scanning range 500-620 nm. The Kalman filter algorithm is successfully applied to resolve the overlapped absorption curves and therefore makes the simultaneous determination of these metallic ions possible without tedious pretreatment. The proposed method is applied to analyse the titled elements in synthetic samples and in environmental samples such as hair, fingernail and river water samples with satisfactory results.
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    Journal of Chemometrics 5 (1991), S. 201-209 
    ISSN: 0886-9383
    Keywords: Uncertainty ; Step function ; Additive model ; Transformation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An additive model is used to express the observed value of a sample characteristic as the sum of the true sample characteristic and a value of the data collection error, commonly known as experimental error. The data uncertainty of the experimental results (or of a survey data set) is defined as the expected squared error. The expected squarred error may change with the sample characteristic, e.g. the error moment could be concentration-dependent. The relationship between the error variance and the analyte concentration may not be very distinct. In such a case the data transformation to stabilize the error moments may not be appropriate. A step function is proposed as an alternative way to represent the second moment of the error. The data uncertainty is defined as the weighted average of the step values of the second raw moment of the error, using the appropriate proportions of the routine samples as weights. The data uncertainties associated with the different data collection stages were evaluated by using regional soil survey data.
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    Journal of Chemometrics 5 (1991), S. 211-225 
    ISSN: 0886-9383
    Keywords: Shot noise ; Expectation-maximization ; Regression ; Deconvolution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple algorithm for deconvolution and regression of shot-noise-limited data is illustrated in this paper. The algorithm is easily adapted to almost any model and converges to the global optimum. Multiple-component spectrum regression, spectrum deconvolution and smoothing examples are used to illustrate the algorithm. The algorithm and a method for determining uncertainties in the parameters based on the Fisher information matrix are given and illustrated with three examples. An experimental example of spectrograph grating order compensation of a diode array solar spectroradiometer is given to illustrate the use of this technique in environmental analysis. The major advantages of the EM algorithm are found to be its stability, simplicity, conservation of data magnitude and guaranteed convergence.
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    Journal of Chemometrics 9 (1995) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 9 (1995), S. 451-457 
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    Keywords: non-linear regression ; optimization ; robust methods ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several robust regression methods, including a new proposal, are described and their properties discussed. Resistance to various types of outliers and non-normality is demonstrated. The techniques are applied to non-linear regression models from chemical kinetics and calibration. Optimization of the types of objective functions encountered when applying robust regression is considered.
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    Journal of Chemometrics 9 (1995), S. 471-481 
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    Keywords: batch prediction ; continuum regression ; multivariate calibration ; sequential prediction ; simultaneous prediction ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In analytical chemistry a single fitted calibration model is used repeatedly to predict the level of the analyte of interest for the specimens comprising the prediction set. Unlike the calibration (or training) set, which is often limited in size, the prediction set can be very large.In the case of multivariate calibration a number of methods such as PLS and PCR are commonly used to construct the calibration model. The set of instrumental measurements and the reference analyte level are available for each specimen in the calibration set. For specimens in the prediction set, only the instrumental measurements are available, since the problem is to predict the analyte level for these specimens. It is not widely recognized that predictions of the analyte levels for individual specimens can be improved by utilizing seemingly unrelated information from the instrumental measurements associated with the other members of the prediction set. In the case of PCR there exists a very straightforward procedure for doing this. A description of the various sources of prediction errors is provided to explain the ability of PCR to utilize this additional information. The use of PCR in this context is illustrated with both a synthetic and a real example.
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    Journal of Chemometrics 5 (1991), S. 291-298 
    ISSN: 0886-9383
    Keywords: Absorbance ratio ; Statistical confidence ; Quality control ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ratio measurements are commonly used to address a variety of analytical problems in environmental, forensic and pharmaceutical laboratories. In absorbance ratioing techniques, analytical chemists rely on the spectral features of the analyte(s) of interest. The absorbances at two wavelengths are monitored and the ratio of these two absorbances is computed. This ratio is then used to confirm the identity of the analyte(s) of interest, the purity of a product of the overlap of chromatographic peaks. These decisions often have far-reaching consequences (e.g. the identification of the source, biogenic or petrogenic, of hydrocarbons in biological tissues or water). Given the cost and the liabilities associated with such decisions, it is unfortunate that these ratios are seldom reported with any statistical confidence. The purpose of this study is to delineate the parameters that affect absorbance ratio measurements. The models that can be used to estimate the statistical confidence in these measurements are derived and evaluated experimentally. The results show that these models can estimate the relative standard deviations in absorbance ratios accurately. They can also estimate the effect of signal-to-noise ratio and the choice of wavelengths on the precision of absorbance ratios.
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  • 78
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    Journal of Chemometrics 5 (1991), S. 299-308 
    ISSN: 0886-9383
    Keywords: Errors in variables ; Orthogonal regression ; Latent variables ; Acid rain ; Acidic deposition ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Techniques for testing for and estimating relative bias between two laboratories are developed and applied to a survey of the chemistry of streams in the United States. The design of the quality assurance program allows estimation of linear corrections for bias as well as testing of the hypothesis of linearity. Designs of this type are useful, but improvements are suggested.
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  • 79
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    Journal of Chemometrics 5 (1991), S. 309-319 
    ISSN: 0886-9383
    Keywords: Confidence intervals ; Products of normal random variables ; Risk/exposure modeling ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In many environmental applications, such as exposure assessment and risk modelling, the desired estimate is a random variable computed as the product of three independently distributed random variables. These variables may not necessarily have the same mean and variance. The method for finding the 100(1 - α)% confidence interval for the mean of the product random variable has been proposed by some practitioners as the product of the 100(1 - α)% confidence interval of the three means. In this paper we show that the distribution of the product of three independent normal variables is not normal. We find the mean and variance of the product distribution. Further, we show that although the mean of the product is equal to the product of the means, the product of the three confidence intervals is not a good approximation of the confidence intervals for the mean of the product variable. The confidence interval of the mean of the product variable may be estimated by computer simulation. An algorithm for estimating the confidence interval for the mean of the product random variable is given. The program implementing this algorithm is given as an appendix.
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    Journal of Chemometrics 5 (1991), S. 321-331 
    ISSN: 0886-9383
    Keywords: Screening ; Ground-water quality ; Monitoring ; Volatile organic compounds (VOCs) ; Optimization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that the presence of 31-35 commonly measured volatile organic compounds (VOCs) in ground water can be detected with small error rates by using screening methods which analyze for a subset of such VOCs. A study of selected data sets indicates that analytical determinations of only from two to eight VOCs will suffice to detect 95% of all VOC hits. It is also shown that a serially optimal algorithm for selecting the VOCs for screening is very nearly as accurate as a globally optimal algorithm and much easier to implement. These conclusions are supported by empirical evidence from two drinking-water data sets and one hazardous waste site data set. Additional research areas are also outlined.
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    Journal of Chemometrics 5 (1991) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 5 (1991), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
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  • 83
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    Journal of Chemometrics 5 (1991), S. 333-343 
    ISSN: 0886-9383
    Keywords: Rank estimation ; Bootstrap resampling ; Canonical correlation ; Excitation-emission matrix ; Singular value decomposition ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rank estimation by canonical correlation analysis in multivariate statistics has been proposed as an alternative approach for estimating the number of components in a multicomponent mixture. A methodological turning point of this new approach is that it focuses on the difference in structure rather than in magnitude in characterizing the difference between the signal and the noise. This structural difference is quantified through the analysis of canonical correlation, which is a well-established data reduction technique in multivariate statistics. Unfortunately, there is a price to be paid for having this structural difference: at least two replicate data matrices are needed to carry out the analysis.In this paper we continue to explore the potential and to extend the scope of the canonical correlation technique. In particular, we propose a bootstrap resampling method which makes it possible to perform the canonical correlation analysis on a single data matrix. Since a robust estimator is introduced to make inference about the rank, the procedure may be applied to a wide range of data without any restriction on the noise distribution. Results from real as well as simulated mixture samples indicate that when used in conjunction with this resampling method, canonical correlation analysis of a single data matrix is equally efficient as of replicate data matrices.
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    Journal of Chemometrics 5 (1991), S. 345-360 
    ISSN: 0886-9383
    Keywords: Three-way PCA ; Three-way PLS ; PARAFAC ; Trilinear ; Unfolding ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For the calibration of chromatographic systems, different methods can be used. One class of methods utilizes three-way approaches. The calibration problem is stated in such a way that the decomposition of a three-way array can serve for the prediction of retention on new stationary phases.Two three-way approaches are presented: the Unfold-PCA and PARAFAC models. The theory of both methods is presented and the differences are highlighted, the main difference being that PARAFAC is a trilinear decomposition whereas Unfold-PCA is not. Both three-way methods are evaluated on a small data set consisting of retention measurements of eight solutes at six mobile phase compositions on six stationary phases. The differences in performance of the two models are minor.For calibration purposes, two variants of the methods are discussed: three-way PLS and an extension of PARAFAC. Again the theory and differences between the two methods are explained. The predictive performance of the two methods is compared using the same data set as earlier. The differences in predictive performance, however, are minor. Both methods are capable of predicting 98% of the variation in the test sets. Yet, there are other considerations when comparing methods than predictive performance, e.g. the quality of the predictions.
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  • 85
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    Journal of Chemometrics 5 (1991), S. 361-374 
    ISSN: 0886-9383
    Keywords: Closure ; Normalization ; Multivariate trimming ; Minimum distance ; Bootstrap ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Compositional data arise naturally in several branches of science, including chemistry, geology, biology, medicine, ecology and manufacturing design. In chemistry, these constrained data seem to occur typically when raw data are normalized or when output is obtained from a constrained estimation procedure, such as might be used in a source apportionment problem. It is important not only for chemists to be aware that the usual multivariate statistical techniques are not applicable to constrained data, but also to have access to appropriate techniques as they become available. The currently available methodology is due principally to Aitchison and is based on log-normal models. This paper suggests new parametric and non-parametric approaches to significantly improve the existing methodology. In the parametric setting, some recent work of Rayens and Srinivasan is extended and a practical regression model is proposed. In the development of the non-parametric approach, minimum distance methods coupled with multivariate bootstrap techniques are used to obtain point and region estimators.
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    Journal of Chemometrics 5 (1991), S. 375-387 
    ISSN: 0886-9383
    Keywords: Determinant criterion ; Multiresponse non-linear fitting ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This work evaluates objective functions for multiresponse non-linear modeling using computer simulations. Tests are performed under a variety of signal-to-noise ratios and noise variance-covariance structures. The standard error of prediction for the model parameters, computed from 50 trials, is used for performance comparisons. The full rank and rank-deficient problems are considered. For the full rank problem one model was investigated, a first-order two-step consecutive reaction model, and two objective functions were considered, the total sum of squares and the determinant criterion. No distinction could be made between the two objective functions for this model.For the rank-deficient case two models were investigated, a first-order two-step consecutive reaction as in the full rank case, and a pH titration model described by the Henderson-Hasselbalch equation. Three objective functions were investigated for the rank-deficient case, the total sum of squares, a weighted total sum of squares and the determinant criterion. The total sum of squares was found to perform poorly under all conditions tested compared to the weighted total sum of squares and the determinant criterion. The determinant criterion was found to perform much better than the other two criteria when the data have a combination of a low signal-to-noise ratio and high variance-covariance noise structure.
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    Journal of Chemometrics 5 (1991), S. 405-409 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 5 (1991), S. 389-403 
    ISSN: 0886-9383
    Keywords: Acoustic emission ; Pattern recognition ; Feature selection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Features used to characterize acoustic emission signals from chemical systems are evaluated with regard to their potential for pattern recognition. Eight chemical systems involving phase transitions, hydration, dissolution and effervescence are employed and treated as separate signal classes. These are compared pairwise and the discriminatory capabilities of about 50 features are investigated by computing Fisher weights. Time domain and frequency domain descriptors are examined. Correlations among the features evaluated are also reported. Recommended descriptors are the mean and median frequencies, frequency bandwidth, number of level crossings (0% and 25%), crest factor (time and frequency domains), half-life, kurtosis and normalized percentiles of the signal and its power spectrum. The effectiveness of the recommended descriptors is demonstrated through the separation of signal classes in two different systems (melting ice and an enzyme-catalyzed gas formation reaction) by principal components analysis.
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 5 (1991), S. 416-416 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 5 (1991) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 5 (1991), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 5 (1991), S. 417-434 
    ISSN: 0886-9383
    Keywords: Factor analysis ; Power density distribution ; Chromatography ; Absorption spectroscopy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Evaluation of the results of factor analysis of sets of spectroscopically detected chromatograms is carried out by examining the shapes of the abstract factors. This is done either by visual inspection or by analysis of the power density spectra produced from them. Owing to constraints imposed by the column function and the spectroscopic instrument function, the information content of the chromatograms necessarily occurs at low spatial frequencies. As a consequence, it appears as relatively broad features in the abstract chromatograms and as a peak in the low-frequency region of the corresponding power density plot. On the basis of examination of the power density distribution, a well-defined distinction is made between primary and secondary abstract factors. The major uncertainty encountered in determining the number of chemical components appears to arise from effects of contaminants in reagents.
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    Journal of Chemometrics 5 (1991), S. 435-453 
    ISSN: 0886-9383
    Keywords: Class-modelling methods ; Potential functions ; Pattern recognition ; Discriminant analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A probabilistic and distribution-free class-modelling technique is developed from potential function discriminant analysis. In the multidimensional space of variables the class boundary is built either by the sample percentile of the probability density estimated by means of potential functions, or by the estimate of the ‘equivalent’ determinant of the variance-covariance matrix. The equivalent determinant is that of a hypothetical multivariate normal distribution whose mean probability density was obtained by potential functions. The bases of this modelling rule are evaluated by means of Monte Carlo experiments. The results on four datasets are used to measure the performances of this method, which equal and sometimes exceed the performances of parametric class-modelling methods based on linear and quadratic discriminant analysis which were used for comparison.
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    Journal of Chemometrics 5 (1991), S. 455-465 
    ISSN: 0886-9383
    Keywords: Correspondence analysis ; Cluster analysis ; Optimization ; Eigenanalysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carey et al. utilized principal components analysis (PCA) to analyze frequency shift data obtained from piezoelectric sensors formed by coating quartz crystals with 27 different GC stationary phases and tested using 14 analytes. The objective of the analysis was to determine an optimal reduced set of coatings for detection of the analytes. The results were correlated with those obtained from cluster analysis. In this paper the data are re-analyzed using correspondence analysis (CA). The advantage of using CA include a symmetric treatment of sensor coatings and analytes and better identification of the representation of the analytes in terms of the detection components. The results obtained by the conjunctive use of PCA, a varimax rotation and cluster analysis were obtained by CA.
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    Journal of Chemometrics 5 (1991), S. 467-486 
    ISSN: 0886-9383
    Keywords: Expert system ; Neural network ; Fuzzy entropy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A fuzzy multivariate rule-building expert system (FuRES) has been devised which also functions as a minimal neural network. This system builds rules from training sets of data that use feature transformation in their antecedents. The rules are constructed using the ID3 algorithm with a fuzzy expression of classification entropy. The rules are optimal with respect to fuzziness and can accommodate overlapped and underlapped clusters of data. The FuRES algorithm combines the benefits obtained from simulated annealing and gradient optimization, which provide robustness and efficiency respectively. FuRES classification trees support OR logic in their inference. The system automatically generates meaningful and consistent certainty factors during rule construction. Unlike other neural networks, FuRES uses local processing which furnishes qualitative information in the rule structure of its classification trees and variable loadings of the weight vectors.
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 5 (1991), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 5 (1991), S. 487-501 
    ISSN: 0886-9383
    Keywords: Calibration ; Locally linear models ; Discrimination ; Optimality ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A calibration situation is considered where the calibration data are split into subsets with good linear relationship between y and x within each group. Different strategies for good prediction in this case are proposed. Modifications for collinear data are considered and a simple simulated data set is used for illustration.
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