Search

Polygonatum sibiricum (P. sibiricum) rhizomes are widely used as a tonic and functional food, and are often processed to enhance their tonic function by repeated steaming and drying. As the most important constituent, the polysaccharide from P. sibiricum rhizomes (PSP) has demonstrated various activities, but the alteration of structural characteristics and activities of the purified PSPs during steaming process was rarely investigated. To well understand the effect of steaming process on the polysaccharides of P. sibiricum, neutral polysaccharides from P. sibiricum rhizomes (PSP0 ~ PSP9) after steaming were first isolated and purified, and then the chemical properties and antioxidant activities were determined. The results showed that the molar ratios of monosaccharides in PSPs were different. The molecular weights of PSPs were increased significantly after the fourth steaming. Morphological studies showed that the surface of PSPs became much tighter during the steaming process. Fourier transform infrared spectroscopy spectra displayed the polysaccharides had similar backbones and chemical groups. Furthermore, the antioxidant activity of PSPs was measured through radical scavenging tests. It was found that the radical scavenging activity of PSPs was elevated strikingly after steaming, and increased gradually with numbers of steaming process. The biological and chemical variance of PSPs revealed considerable segregation of PSP0, PSP1 ~ PSP4 and PSP5 ~ PSP9. In conclusion, our results proposed the fourth time as the optimal number of steaming to extract functional polysaccharide from P. sibiricum rhizomes.

Despite recent advances, Chagas disease is still a public health issue that requires more efforts in order to develop efficient and safe drugs. Plants and fungi are the main source for semi-synthetic natural-inspired new molecules to treat human illness. In the present work, we summarize the main findings of natural-derived and semi-synthetic alkaloids against Trypanosoma cruzi. Over the last 10 years, at least seven alkaloids groups with structural modifications, including 130 molecules and almost 100 semi-synthetic compounds derived from natural alkaloids, including hybrids molecules, modifications of aliphatic chain extension, chemical groups, and heteroatoms, were analyzed for its toxicity over parasites and mammalian cells. According to the available data, there are a good number of promising natural and/or semi-synthetic alkaloids that would meet the criteria to become candidates in the drug discovery process against Trypanosoma cruzi parasites. Main scaffolds that deserve special attention are natural quinolones, isoquinolines, and semi-synthetic hybrids molecules.

This research aims to contribute to the discussion of ceramic objects found at the Monte Castelo shellmound, an archaeological site located at south-west Amazonia, Brazil. This paper provides the results of a preliminary characterization of eighty-four pottery samples using instrumental neutron activation analysis (INAA) and dating by thermoluminescence (TL). The results showed the existence of three different chemical groups whose dates range from 3000 to 1500 BP. confirming changes in clay sources during that period. These results agree with previous studies about the technological changes and continuities in the Bacabal phase, one of the oldest ceramic cultures of South America.

Clostridium difficile is a leading cause of morbidity and mortality particularly in hospital settings. In addition, treatment is very challenging due to the scarcity of effective therapeutic options. Thus, there remains an unmet need to identify new therapeutic agents capable of treating C. difficile infections. In the current study, we screened two FDA-approved drug libraries against C. difficile. Out of almost 3,200 drugs screened, 50 drugs were capable of inhibiting the growth of C. difficile. Remarkably, some of the potent inhibitors have never been reported before and showed activity in a clinically achievable range. Structure-activity relationship (SAR) analysis of the active hits clustered the potent inhibitors into four chemical groups; nitroimidazoles (MIC(50)= 0.06 − 2.7 μM), salicylanilides (MIC(50)= 0.2 − 0.6 μM), imidazole antifungals (MIC(50)= 4.8 − 11.6 μM) and miscellaneous group (MIC(50)= 0.4 − 22.2 μM). The most potent drugs from the initial screening were further evaluated against additional clinically-relevant strains of C. difficile. Moreover, we tested the activity of potent inhibitors against representative strains of human normal gut microbiota to investigate the selectivity of the inhibitors towards C. difficile. Overall, this study provides a platform that could be used for further development of potent and selective anticlostridial antibiotics.

A series of novel 5-alkoxyfuran-2(5H)-one derivatives was synthesized, and characterized by 1H NMR, 13C NMR and HRMS. Biological activities of all the title compounds were evaluated systematically. Preliminary bioassays indicated that most of the compounds exhibited moderate insecticidal activities against Aphis craccivora and Nilaparvata lugens at 100 mg/L. Compounds 4h and 4w exhibited 100% mortality rate against Aphis craccivora at 100 mg/L, and compound h exhibited good mortality rate against Aphis craccivora and Nilaparvata lugens (60% and 75%, respectively) even at 4 mg/L. The results demonstrated the impact of various chemical groups on insecticidal activities and provided a potential clue for further exploring novel high-effective broad-spectrum insecticides.

Nanoparticles (NPs) are useful for radiotherapy. Currently, efforts are underway globally for the development of novel titanium dioxide NPs (TiO2-NPs) that exhibit both contrast effects and anti-tumor effects. In this study, the image contrast properties of TiO2-NPs were evaluated using a clinical magnetic resonance imaging (MRI) system and a clinical computed tomography (CT) scanner, as the use of TiO2-NPs as an anti-cancer agent has been reported in several reports. An obvious difference in visualization was observed between the control and TiO2-NP samples on T2-weighted images. These results suggest that TiO2 can potentially be used as a novel theranostic drug with radiosensitizing ability and radiological diagnostic ability, through modification of chemical groups on its surface, and as a component of drug delivery systems.

The elytra of females of the white-spotted longhorn beetle, Anoplophora malasiaca (Coleoptera: Cerambycidae), are coated with a contact sex pheromone, which was previously shown to be composed of at least three chemical groups. Individually, the chemical groups had little pheromonal activity, but a blend of all three exhibited activity equal to that of the crude female extract. Two groups are female-specific aliphatic hydrocarbons and ketones, which were previously synthesized and confirmed to elicit mating behavior. The third group consists of three lactones, gomadalactones A, B, and C, whose chemical structures were previously identified. These have now been synthesized, and the contact sex pheromone activities of synthetic gomadalactones A, B, and C, and the diastereomer of gomadalactone C, were tested in bioassays in this study. When tested in combination with synthetic hydrocarbons and ketones at the same doses as found in female elytra extract, the individual gomadalactones and a blend showed potent pheromonal activity equivalent to that of the crude extract of the elytra of female beetles. This completes the identification of the essential components of the contact sex pheromone of A. malasiaca. Redundancy of components in the hydrocarbon and ketone groups required to elicit mating behavior was observed previously, and this was also true for the gomadalactones.

This study aims to determine the urinary stones' chemical compositions, morphologies, and crystal size by using X-ray diffraction, scanning electron microscopy with energy dispersive X-ray, and Fourier transform infrared spectroscopy. This study has been conducted with 30 urinary stones from the 30 patients who were treated at the Department of Urology in Mersin University Hospital (Mersin, Turkey). With respect to the detected phase compositions, results were classified into four chemical groups: oxalates (43.3%), phosphates (13.3%), urates (6.7%), and mixed stone (36.7%).

Heat modification is an effective method of reducing the hygroscopicity of wood. To gain a detailed understanding of water adsorption mechanism of heat-treated wood, the molecular interaction between the adsorbed water and heat-treated wood was studied via micro-FTIR spectroscopy. The micro-FTIR spectra of heat-treated wood exhibited a typical change in the chemical groups resulting from the heat treatment. In addition, the micro-FTIR spectra at different relative humidity levels confirmed the chemical sites at which the heat-treated wood adsorbed the water. A component band analysis of these difference spectra revealed three component peaks that were assigned to strongly, moderately, and weakly hydrogen-bonded water, respectively. Based on this variation of these three types of adsorbed water, the water adsorption process of heat-treated wood was divided into three different sections. Furthermore, the structure of the water adsorbed in these three sections was demonstrated. The results of this study provide a valuable insight into the state of water present in heat-treated wood.

The objectives of this study were to determine the relationship between the results provided by the classical CIELab (ΔEab*) and the CIEDE2000 (ΔE00) formulas and the gingival color space using the Bland and Altman limits of agreement, to use this relationship to establish the equivalences between the gingival color thresholds of perceptibility of both formulas, and to evaluate whether the relationship between ΔEab* and ΔE00 is modified depending on the axis in which the changes occur. The means of the L*, a*, and b* coordinates of the 21 gingiva porcelain samples (Heraceram, Heraeus Kulzer Mitsui Chemical Groups) were used and the differences in color were calculated in 210 pairs of samples using the CIELab (ΔE*ab) and CIEDE2000 (ΔE00) color-difference formulas. The results obtained with these formulas were compared and the limits of agreement after a logarithmic transformation of the data were obtained. The relationship between both formulas was ln ΔE00 = - 0.22 + ln ΔEab*. The results obtained with the CIELab formula were between 1.01 (95% confidence interval 0.98-1.03) and 1.54 (95% confidence interval 1.52-1.59) times higher than those obtained with the CIEDE200 formula. In the gingiva color space, the scale factor between the CIEDE2000 and CIELab values changes from 0.63 to 1.02, such that providing an accurate scale factor between both values proves difficult. The pairs with the highest ratio were those where the difference in color was mainly due to changes in lightness, whereas the pairs with the smallest ratio were those where the difference in color was mainly due to changes in the blue-yellow or green-red axes.

Dmitri Mendeleev’s detailed prediction in 1871 of the properties of three as yet unknown elements earned him enormous prestige. Eleven other predictions, thrown off without elaboration, were less uniformly successful, thanks mainly his unbending adherence to the structure of his table and his failure to account for the lanthanides. At the end of his life he returned to his table without making the required changes, and added a theoretical discussion of elements lighter than hydrogen. The overall balance of success and failure is nevertheless in his favour. There may now be a similar failure to understand the ultra-heavy elements because of adherence to the pattern of chemical groups.

Earlier research has shown that several common late antique glass types circulate in Cyprus between the fifth and the seventh century AD, specifically Levantine 1, HLIMT, HIMTa, HIMTb and Egypt 1, HIT, Roman and a plant ash glass. By investigating the glass material from Yeroskipou-Agioi Pente, Maroni-Petrera, and Kalavasos-Kopetra, we aimed to refine the chemical groups present within three late antique Cypriot sites and define the relations between trace elements obtained from LA-ICP-MS. Our data demonstrate compositional patterns that can be exploited to provenance late antique glass by investigating the REE-bearing mineral fractions, the amount of zircon and the carbonaceous fraction of the sand. In addition, Nb and Ti display a strong linear relation which depends on the glass type. Finally, the paper discusses the occurrence of glass recycling on the island and how this activity influenced the concentration levels of specific trace elements. Our study thus sets out an analytical framework to identify recycling events tailored on each compositional type.

Essential oils (EO) obtained from Xylopia parviflora root bark and Hoslundia opposita leaf via hydro distillation were analysed by GC-MS and evaluated for their insectifugal (repellent) and insecticidal activities against cowpea seed bruchid (Callosbruchus maculatus Fabricius), a cosmopolitan pest of cowpea seeds. X. parviflora was predominated by sesquiterpenes (59.57%), with the main compounds being β-himachalene (22.68%), 1,7,7,Trimethylbicyclo[2.2.1]hept-5-en-2-ol (19.68%), β-elemene (14.41%), 5(1H)-Azulenone, 2,4,6,7,8,8a–hexahydro-3,8-dimethyl-4-(1-methylethylidene)-(85-cis)- (12.38%) and (−)-α-parasinsen (8.34%). The predominant compounds in H. opposita EO were 1,8-cineole (61.15%), followed by α-terpineol (16.81%) and β-phellandrene (13.25%). Percentage repellence at application rates of 0.66–1.32 μl/cm2 (46.93–73.07%) was significantly (p

Pategrás is a typical semi-hard cheese of Argentina. Over the years, successive technological changes have been applied to its manufacture, being the addition of propionibacteria (PAB) one of the most relevant. The aims of the present work were to determine some physicochemical parameters and volatile composition of commercial samples and evaluate the effect of PAB on volatile profile during ripening, by comparing cheeses made at pilot scale, with or without added PAB. Commercial samples displayed some differences in terms of rough composition, mainly ripening degree. Acids, especially short-chain fatty acids (C2to C4), were the most representative group of volatile compounds, being propanoic acid the most abundant. Alcohols and ketones were other chemical groups that prevailed in the volatile profiles whereas esters and aldehydes constituted a minority fraction. For cheeses made at pilot scale, the levels of several compounds such as diacetyl, acetoin, primary alcohols, ethyl esters, branched-chain aldehydes, branched-chain alcohols, branched-chain acids, and short-chain fatty acids were significantly influenced by the presence of PAB. Most of the changes observed in the volatile fraction during ripening and the differences found between cheeses made with and without added PAB were in agreement with published data. This work provides detailed information about the volatile composition of Pategrás cheeses made with the inclusion of PAB, which contribute to the characterization of the most traditional Argentinean semi-hard cheese. Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Peralta, Guillermo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Candioti, Mario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

This work comprises the utilization of instrumental neutron activation analysis to determine the concentration of 24 chemical elements in pottery shards from two large archaeological sites in central Amazon, Lago Grande and Osvaldo. The multidimensional data set was analyzed by cluster and principal component analysis for defining chemical groups of pottery. The results were correlated to potential exchange networks driven by three mechanisms: trade, exogamic marriage and territorial integration in the region. All of them have important consequences for archaeological research regarding the Amazonian pre-colonial occupation.

Enzymes or proteins are commonly present in oligomeric forms for active biological functions. The formation of protein oligomers, either in nature or by artificial means, can take place via covalent bonding or through weak-bond-network associations. Disulfide bonds are more common in forming covalent protein oligomers. Covalent bound protein oligomers usually have additional elements introduced, while proteins associated through weak-bond-networks usually do not involve any additional bound chemical groups. Proteins are commonly present in stable forms or folds. Oligomerization can occur when stable proteins unfold, creating exposed interfaces for association interactions. One well-known process of weak-bond-network oligomerization is domain swapping (DS). Separating the two touching/interacting domains creates opportunities for similar interactions with different protein molecules, leading to oligomerization. Both disulfide bonding and DS oligomerization can be dynamic (or reversible) at least at low Degree of Polymerizations (DPs). The dynamic nature of the protein oligomerization is important for bioactivity control. The morpheein model and the polymorph model are thus important in quantifying enzyme catalyzed biotransformations. Disulfide bonding and DS can act together to form supramolecules. The formation of supramolecules, such as amyloids, in nature can be benign or harmful. Industrial applications of protein oligomerization exploit the special functions /properties of the resultant supramolecules, such as multiple biofunctions, niche structure, etc..

In the present work, an electrospun nanofibrous textile composed of polyurethane (PU), sodium bicarbonate ( $$\hbox {NaHCO}_{3}$$ ) and pantothenic acid (PA) is developed for treating chronic wounds. Wounds are a common health problem and in particular, the chronic wounds such as vascular ulcers, diabetic ulcers and pressure ulcers cause a large number of morbidity and mortality. The main problems of the chronic wounds are prolonged inflammation phase and presence of acidic environment. These events deactivate the operation of growth factors and also the progression of natural healing mechanism. Hence, various types of advanced textile-based dressings are developed to address the clinical complications associated with chronic wound management. The prepared electrospun scaffolds were characterized to study their physicochemical and haemocompatible properties. The scanning electron microscopy micrographs depicted continuous, smooth-interconnected nanofibrous morphology of PU–NaHCO $$_{3}$$ –PA scaffolds. The Fourier transform infrared spectroscopy spectra indicated the addition of NaHCO $$_{3}$$ and PA-based hydrophilic chemical groups, which significantly enhanced the wettability of the composites. Further, the PU–NaHCO $$_{3}$$ –PA composite membrane inferred to have a highly porous structure with the mean porosity of 79.4 ± 4.8%, which may provide a conducive environment for adherence and proliferation of skin cells. The composite scaffold also offers a highly haemocompatible surface by delaying coagulation of blood through contact activation pathways and by limiting red blood cells damage. Therefore, the excellent physicochemical properties, blood compatibility and the delivery of PA are anticipated to speed up the impaired healing process of chronic wounds.

The ability to attach a variety of chemical groups to one position in a molecule facilitates the search for compounds that have useful properties. Reactions have been reported that could transform how chemists do this. Cross-coupling reactions at carbon–sulfur bonds.

The function of histone proteins can be modified through addition or removal of certain chemical groups. The addition of a serotonin molecule is a newly found histone modification that could influence gene expression. A nuclear role for serotonin discovered.

Pharmaceuticals are one of the chemical groups largely used in health care, diagnosis aids, cure, treatment, and prevention of disease. Increasing production and use of pharmaceutical products has led to the entry of these products into the environment and eventual pollution. Several processes have been studied including the use of ultrasound for the removal of these pollutants from the aquatic environment. This review summarizes recent research advances dealing with the development of sonochemical technologies for the degradation of pharmaceutical organic pollutants. The review also includes the mechanism of sonochemical processes, the characteristics of irradiation sources, and the types of reactors used. Moreover, the important factors affecting the sonochemical oxidation efficiency are discussed, including the electrical power, frequency, and temperature. Finally, this paper discusses the recent applications of sonochemical processes on the degradation of pharmaceutical organic pollutants and suggests new research directions for the development of this promising technology.

This paper aims at studying the elementary chemical composition of 70 ceramic fragments from the Sao Paulo II archaeological site by instrumental neutron activation analysis. The concentration data was studied next using multivariate statistical methods, such as cluster analysis, principal component analysis and discriminant analysis. The results showed three different chemical groups of samples regarding the similarity/dissimilarity between the samples. Ceramics from each group have been selected and dated using thermoluminescence. The firing temperature of the ceramics was determined by electron paramagnetic resonance.

Scanning probe microscopes can be used to image and chemically characterize surfaces down to the atomic scale. However, the localized tip-sample interactions in scanning probe microscopes limit high-resolution images to the topmost atomic layer of surfaces, and characterizing the inner structures of materials and biomolecules is a challenge for such instruments. Here, we show that an atomic force microscope can be used to image and three-dimensionally reconstruct chemical groups inside a protein complex. We use short single-stranded DNAs as imaging labels that are linked to target regions inside a protein complex, and T-shaped atomic force microscope cantilevers functionalized with complementary probe DNAs allow the labels to be located with sequence specificity and subnanometre resolution. After measuring pairwise distances between labels, we reconstruct the three-dimensional structure formed by the target chemical groups within the protein complex using simple geometric calculations. Experiments with the biotin-streptavidin complex show that the predicted three-dimensional loci of the carboxylic acid groups of biotins are within 2 Å of their respective loci in the corresponding crystal structure, suggesting that scanning probe microscopes could complement existing structural biological techniques in solving structures that are difficult to study due to their size and complexity.

This research explored some factors involved in the emergence of intraverbals as demonstrated by Perez-Gonzalez, Herszlikowicz, and Williams (2008) in three experiments. Eleven adults learned to say the chemical elements corresponding to two chemical groups (the A-B relations) and to say the atomic numbers of two elements (the B-C relations). Thereafter, we probed the relations that result from combining these stimuli. For example, we asked the groups corresponding to the atomic numbers (the C-A relations). In Experiment 1, we taught A-B and B-C and probed the remaining relations without additional teaching. In Experiment 2, with Categories, participants learned to say the categories of the exemplars (i.e., “What is polonium?” –the correct answer was “an element”). In Experiment 3, with Exemplars, participants learned to say the exemplars of the categories (i.e., “Name a chemical element”; the correct answers were the two chemical elements). The Categories facilitated emergence in some but not all participants. The Exemplars was shown to be effective in promoting the emergence of the emergent relations. These results indicate that the simpler intraverbals (Categories and Exemplars) play a role in the emergence of the more complex intraverbals.

Carbon–hydrogen bonds in organic molecules can be cut to install other chemical groups on the carbon atom, but these reactions have been limited. A catalytic palladium complex opens up fresh opportunities. Carbon–hydrogen bonds in organic molecules can be cut to install other chemical groups on the carbon atom, but these reactions have been limited. A catalytic palladium complex opens up fresh opportunities.

Hepatoma cells (Hepg2s) as typical cancer cells cultured on hydroxyl (−OH) and methyl (−CH3) group surfaces were shown to exhibit different proliferation and morphological changes. Hepg2s cells on −OH surfaces grew much more rapidly than those on −CH3 surfaces. Hepg2s cells on −OH surfaces had the larger contact area and the more flattened morphology, while those on −CH3 surfaces exhibited the smaller contact area and the more rounded morphology. After 7 days of culture, the migration of Hepg2s cells into clusters on the −CH3 surfaces behaved significantly slower than that on the −OH surfaces. These chemically modified surfaces exhibited regulation of Hepg2s cells on proliferation, adhesion, and migration, providing a potential treatment of liver cancer.

Molecular simulations are used to explore kinetic-friction modification in nanoscale fluid layers of oil and additive confined between sheared parallel walls. The molecules are represented by coarse-grained bead-spring models that reflect the essential solvophilic and solvophobic natures of the chemical groups. The degree of friction modification is surveyed as a function of wall separation, sliding velocity, additive molecular weight and architecture, and oil-additive composition. As a rule, the kinetic-friction coefficient is found to increase first linearly and then logarithmically with increasing sliding velocity. From the results for different additive molecules, some subtle but systematic effects are found that point towards an optimum molecular weight and architecture.

The chemical composition of biologically active compounds of the common duckweed (Lemna minor) was studied. A titrimetric method was used to assay the total iodine content, a spectrophotometric method was used for flavonoids, expressed as luteolin-7-glucoside; gas chromatography/mass spectrometry was used to identify 32 lipophilic substances of various chemical groups. Atomic emission spectrographic studies identified 14 macro and trace elements in the common duckweed. Studies of biologically active substances in the common duckweed are of interest for further investigation of its pharmacological properties with the aim of seeking new medicinal agents.

X-ray fluorescence analysis study of 44 archaeological pottery samples collected from Tell Jendares site north-west of Syria has been carried out. Four samples of the total previous investigated samples were obtained from the kiln found on Tell Jendares site. Seventeen different chemical elements were determined. The XRF results have been processed using two multivariate statistical cluster and factor analysis methods in order to determine the similarities and correlation between the selected samples based on their elemental composition. The methodology successfully separates the samples where three distinct chemical groups were discerned.

Data on levels and accumulation profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/ Fs) and dioxin-like polychlorinated biphenyls (PCBs) in cetaceans are scarce. This paper presents data on the concentrations and accumulation features of PCDD/Fs and dioxin-like PCBs in muscle of minke whales (Balaenoptera acutorostrata) and long-beaked common dolphins (Delphinus capensis) collected from Korean coastal waters. The residue levels in cetaceans were in the order of mono-ortho PCBs> non-ortho PCBs>PCDFs>PCDDs. Total toxic equivalent (TEQ) concentrations in muscle of minke whales and common dolphins from Korea were lower than those reported for cetaceans and seals from other countries. The accumulation profiles of PCDD/Fs and dioxin-like PCBs were different between the cetacean species. Concentrations of PCDD/Fs and dioxin-like PCBs in common dolphins were significantly higher than those measured in minke whales, due to differences in the habitat and diet. The relative contribution of individual chemical groups to total TEQs was different between the cetacean species, suggesting different exposures and metabolic activity.

Over the past years, atomic force microscopy (AFM) has emerged as a powerful tool for imaging the surface of microbial cells with nanometer resolution, and under physiological conditions. Moreover, chemical force microscopy (CFM) and single-molecule force spectroscopy have enabled researchers to map chemical groups and receptors on cell surfaces, providing valuable insight into their structure-function relationships. Here, we present protocols for analyzing spores of the pathogen Aspergillus fumigatus using real-time AFM imaging and CFM. We emphasize the use of porous polymer membranes for immobilizing single live cells, and the modification of gold-coated tips with alkanethiols for CFM measurements. We also discuss recording conditions and data interpretation, and provide recommendations for reliable experiments. For well-trained AFM users, the entire protocol can be completed in 2-3 d.

Alicante and Jijona turron are honey- and almond-based confectionery products very famous in Spanish countries, especially during Christmas. In this study, the role of different types of honey (rosemary, orange blossom, and control—a mixture of sugars resembling the sugars composition of real honey) in the aroma and flavor of these confections was studied. Volatile compounds in turron samples were extracted using simultaneous distillation–extraction and finally isolated, quantified and identified using GC-MS. Two different types of panels were used, trained and consumer, for studying the aroma and flavor intensities of turron samples. Aldehydes, aromatic hydrocarbons and furans were the predominant chemical groups in turron samples. The first conclusion was that terpenes and aromatic hydrocarbons decreased with the heating of the boixet step while pyrazines, furans, and pyrroles increased. Chemical feelings, such as cooling and pungency, are the best tool to discriminate among products containing and non-containing honey. Products containing honey were more aromatic and obtained higher satisfaction values than those prepared from a mixture of sugars.

Volatile compounds in afitin, iru and sonru, three traditional food condiments produced in Benin by natural fermentation of the African locust bean (Parkia biglobosa) were identified and quantified, using the Likens-Nickerson simultaneous distillation-extraction method and GC-MS analysis. A total of 13 chemical groups of volatile compounds were identified and classified in six major groups: pyrazines, aldehydes, ketones, alcohols, esters and benzene derivatives. From these groups, 2,5–dimethylpyrazine, tetramethylpyrazine, 3-methylbutanal, 2-decanone, 3,5-dimethylphenylmethanol, ethyl linoleate and chlorobenzene were found in higher amounts in the three condiments. Afitin was characterized by high concentration of 2-decanone, whereas 2,5-dimethylpyrazine, tetramethylpyrazine, 3-methylbutanal and ethyl linoleate were found particularly in higher concentration, both in iru and sonru.

The common practice for determination of orientational angle of interfacial molecular groups with the interfacial sum frequency generation vibrational spectroscopy (SFG-VS) is to measure the intensity ratio between two SFG intensities at a certain vibrational frequency with different polarization directions. Because sometimes the SFG at one polarization direction is too weak to be measured accurately, this ratio usually has big uncertainty, and consequently it is impossible to obtain accurate orientation parameters. Thus the corresponding orientation angle was not accurately calculated. Through analyzing the basic relationship between the orientation angle and SFG intensity, we found that the null angle method would be suitable for such cases. The null angle measurement is simple, precise and easy to realize, therefore can greatly improve the accuracy of orientation angle. Using this method, we determined the orientation angle of the methyl group of methanol orients about 31.8 ± 2.4° from the surface normal at the air/methanol interface, much more accurate than the previously reported value of < 42°. The null angle method provides a reliable experimental analytical tool for studying the orientation of the chemical group or chemical bond at interfaces.

The possibility of specific cleavage of a single-stranded DNA fragment due to cooperative action of two oligonucleotide derivatives bearing chemical groups (at the 3"-phosphate and 5"-thiophosphate ends, respectively) located close to each other in a complementary complex is demonstrated.

Preparations containing complexes of biologically active substances extracted from medicinal plants act upon various systems of the organism, including the antioxidant protection system. For this reason, phytopreparations can be used both for the prophylaxis and for the complex therapy of free-radical pathologies. The antioxidant activity of phytopreparations is determined by the features of their chemical structures and by the content of biologically active substances. Therefore, it is necessary to study how the qualitative and quantitative composition and the interaction between various biologically active substances of medicinal plants influence the antioxidant activity of phytopreparations. Previously [1] we estimated the antioxidant activity of tinctures and balsams. This study is devoted to the antioxidant properties of individual biologically active compounds and aqueous tinctures from raw plant materials. Based on these data, we established relationships between the level of antioxidant activity of phytopreparations and the content of various biologically active substances belonging to various chemical groups.

The discovery that proinflammatory prostaglandins are produced by cyclooxygenase-2 (COX-2), an inducible isoform of the constitutive cyclooxygenase-1 (COX-1), opened a new frontier in the treatment of inflammatory diseases, because the selective inhibition of COX-2 can lead to therapeutically effective compounds which do not have the common side effects of classical non-steroidal antiinflammatory drugs (NSAIDs). Different crystallographic structures of both free COX-1 and COX-2 as well as complexes with inhibitors have been solved. Because of the great similarity between the two enzymes, it is difficult to detect the most important structural and physicochemical features that would be useful for designing inhibitors with an improved selectivity. In this paper we describe the application of a chemometric procedure to the study of COX-2 selective inhibition. This method, developed to reveal the most suitable regions of isoenzymes for the design of selective ligands, also has a very practical utility. GRID multivariate characterization of the enzymes and subsequent Principal Component Analysis (PCA) of the descriptor variables allow the identification of chemical groups that could be added to a core template structure to increase ligand selectivity.

In Finland, biomonitoring action levels (BAL) have been set since the 1970s. There are different ways of setting these BALs. The value for blood lead is based on legislation. Exposure limits have been set on the basis of the indicative values for carbon disulfide, ethylene benzene, toluene, and phenol. The number of BALs set by the Finnish Institute of Occupational Health (FIOH) has increased year by year, and we now have BAL values for more than 36 different chemicals or chemical groups. The Institute annually publishes a booklet with the latest information about the biomonitoring tests, sample collection, and limit values. The booklet is also available in English as a web version (http:/(/)www.occuphealth.fi/tt/bio/guide346. htm).

Fragile chemical groups can be shielded from harsh reaction conditions by temporary protection. This approach is conventional wisdom for organic synthesis, but is it always the best solution?

One hundred and eighty-seven metal samples, recovered from the fortified mission of Ste. Marie II and nearby villages on Christian Island, include 3 samples of native copper, 22 samples of European copper, 19 samples of brassy copper (≤8% Zn), 141 brass samples and 2 samples of lead. The European copper samples form 5 distinct chemical groups, possibly coming from 5 different copper kettles. The brassy copper samples are more difficult to group. When the brass samples are sorted by Ag and As, they form 2 major groupings: group 1 with high Ag and low As contents; group 2 with similar Ag and As contents through to low Ag and high As contents. Group 1 consisted of 11 chemical sub-groups and 6 outliers, while group 2 contributed 14 sub-groups and 14 outliers. This combines to give a total of 45 potentially unrelated brass chemistries, and leads to the possibility of as few as 20 different brass trading items (mainly kettles) from which the samples were cut. The small sub-sets of samples from the sites away from Ste. Marie II tended to fit within chemical groups found there, suggesting some possible inter-site contemporaneity.

Accurate prediction of the response of an individual patient to lithotripsy remains impossible. Certain factors such as the chemical composition, size, and position of the calculus are known to be important in determining the success rate. This paper reports the use of magnetic resonance imaging (MRI) to evaluate 141 urinary calculi in vitro. A wide range of signals for each chemical type of calculus was found on each of the three imaging sequences used (T1-weighted, T2-weighted, and proton density). None of the chemical groups examined showed a typical MRI profile allowing it to be distinguished from the other groups. Analysis of variance showed a statistical difference between signals for apatite and struvite on the T1-weighted sequence, and between struvite and uric acid on the proton density sequence (both, P < 0.05). These results show for the first time that MRI is capable of distinguishing between different chemical types of stones. This is particularly important for the comparison of struvite and apatite which appear to be similar in conventional investigations but have quite different hardness values. Further work is in progress correlating the results of this study with stone microhardness and extracorporeal shockwave lithotripsy fragility tests to determine whether MRI accurately predicts the success of lithotripsy.

Thirty elements were determined by two INAA methods in sediment core samples from N. Saronikos Gulf, Greece, and the results were subjected to multivariate analysis. This procedure resulted in the separation of samples into chemical groups that were environmentally meaningful and sufficient to (a) distinguish among different pollution sources; (b) trace the routes and the extent of pollution in sediments; and (c) define the least affected areas representing the geochemical background. The principal components analysis of the analytical data for 18 selected elements revealed that, among the elements determined in this study, the most discriminating were As, Sb, Ag, Ca, Au, Zn and the rare earth elements (REE).

Studies were conducted to explore structure-activity relationships for 4'-N,N-dimethylamino-1'-phenylazo-3-pyridine and nine structurally related compounds in Salmonella typhimurium tester strains TA1535, TA100, TA1537, TA1538, TA98. Each compound was tested for mutagenicity at five or more concentrations that varied from 10-5000 micrograms/plate. We used the standard plate test and the investigations were carried out both in the absence and presence of Aroclor-1254-induced rat-liver homogenate and the components of the NADPH-generating system. Negative response was observed for 4'-N,N-dimethylamino-1'-phenylazo-3-pyridine and five of its analogues (4'-N,N-diethylamino-1' phenylazo-3-pyridine; 4'-N,N-di-(beta-hydroxyethylamino)-1' phenylazo-3-pyridine; 4'-N-methylamino sulfonic acid-1'-phenylazo-3-pyridine; 4'-N,N-dimethylamino-6'-acetamido-1' phenylazo-3-pyridine, and 4'-N,N-di-(beta-hydroxyethylamino)-6'-methyl-l' phenylazo-3-pyridine). When S9 induced by Aroclor-1254 was present, the compound 4'-N,N-dimethylamino-6-methoxy-1' phenylazo-3-pyridine exhibited mutagenic activity in the two strains TA1538 and TA98. The compound 4',6'-diamino-3-methyl-1'-phenylazo-3-pyridine was also mutagenic, both in the presence and in the absence of S9 mix. The two compounds 4'-N,N-dimethylamino-6-butoxy-1'-phenylazo-3-pyridine and 4'N,N-di-(beta-hydroxyethylamino)-1'-phenylazo-3-[6-N,N-di-(beta- hydroxyethylamino) pyridine were either weakly mutagenic or nonmutagenic. On the basis of these data, it is concluded that the mutagenicity of phenylazo-3-pyridines, like monocyclic aromatic amines and azo dyes, is influenced by the nature of the substituent chemical groups and their positions in the molecular structure of the compounds.

'Jumping genes' can wreak havoc by hopping about a genome. Some plants can keep them under control by modifying them with certain chemical groups.

Two different instrumental neutron activation analysis (INAA) methods were applied to characterize chemically 74 ceramic roof tile samples, found in the town of Pella, Greece and dated back to the Hellenistic Period (3rd century B. C.). The samples were first analyzed for 17 elements with a 4 hour irradiation and two counts and then re-analyzed for 9 elements with a 1 minute irradiation and two counts of short-lived radioisotopes. The results of both methods were very similar, showing the validity of the rapid INAA method (1 min irradiation) in the study of ancient ceramics. All samples were divided into 4 chemical groups, each one representing a different tiling.

Atomic force microscopy is applied to image the location of chemical groups inside single protein complexes.

Controlling the positions at which chemical groups attach to benzene rings is vital for the synthesis of materials and medicines. A reaction that targets a normally inaccessible position takes chemists closer to this goal. See Letter p.518 The functionalization of unactivated carbon-hydrogen (C–H) single bonds is an efficient and rapid method for the generation of complex molecules from simpler ones. However, it is difficult to achieve selectivity of C–H activation in target molecules possessing multiple inequivalent C–H bonds. These authors report a class of easily removable 'templates' that direct the activation of distal meta-C–H bonds (more than ten bonds away) of a tethered arene. The innovative structures that are generated through this method are extremely hard to access by traditional methods and may provide different avenues for the development of innovative C–H activation reactions.

Geochemical fingerprinting of obsidian sources was first applied in the Mediterranean region nearly four decades ago. Since then, a number of analytical methods (e.g. INAA, XRF, SEM/Microprobe, ICP-MS) have proven successful in distinguishing the Mediterranean island sources of Giali, Lipari, Melos, Palmarola, Pantelleria, and Sardinia. Moreover, recent geoarchaeological surveys of the central Mediterranean sources have resulted in the more precise location and documentation of each obsidian flow or outcrop, and multiple chemical groups have been identified on at least three of the islands. The ability to specifically attribute artifacts to one of at least five obsidian flows in the Monte Arci region of Sardinia, for example, has enabled the study of specific patterns of source exploitation and the trade mechanisms which resulted in the distribution of obsidian hundreds of kilometers away during the Neolithic period (ca. 6000-3000 BC).Results are presented here from the chemical analysis of 186 artifacts from several sites in Sardinia and Corsica as part of the largest and most comprehensive study of obsidian sources and trade in the Mediterranean. Analyses of large numbers of artifacts demonstrate the differential use of island subsources, which may be attributed to factors such as access (e.g. topography, distance from coast), size and frequency of nodules, and mechanical and visual properties. The patterns of source exploitation revealed by this study specifically support a down-the-line model of obsidian trade during the neolithic period. In addition, the spatial and chronological patterns of obsidian distribution may be used to address such issues as the colonization of the islands; the introduction of neolithic economies; and the increasing social complexity of neolithic and bronze age societies in the central Mediterranean.

Some alcohols can't be made in a way that controls the crucial arrangement of chemical groups in the molecule. A reaction that uses common laboratory reagents offers a practical route to these compounds.

The traditional approach of coupling estimates of human exposures to individual chemicals with laboratory studies of the toxicity of the chemicals as the basis for quantitative assessments of risk is not adequate when considering problems near hazardous waste sites. For example, there are (a) too many chemicals and mixtures involved, (b) containment uncertainties, and (c) future exposure problems associated with groundwater and soil contamination. Among the items to be considered in expanding the dimensions of risk assessment methodologies of the past are (a) identification of chemical groups or of dominant toxic chemicals of principal concern and the likely man-made as well as natural pathways for environmental migration, (b) the role of biological monitoring in addition to traditional monitoring approaches, and (c) the coupling of monitoring data with past, current, and future population activity patterns and with epidemiological and other health data.Monitoring data is a key in risk assessments since there is little likelihood that materials balances or modelling will provide authoritative information concerning exposure levels. The use of monitoring data from control areas and from nationwide baseline surveys in developing comparative risk assessments is particularly important. Finally, recent experience provides us with a number of practical guidelines for designing and carrying out monitoring programs that will provide authoritative and useful data. *** DIRECT SUPPORT *** AZ802019 00002.

1. A new method of deasphalting reduced crudes with a moving bed of adsorbent has been investigated; this process gives efficient separation of the basic chemical groups and a high yield of valuable oil components. 2. The primary deasphalted oils obtained from a series of Volgograd, Perm', Bulgarian and Zhirnovsk crudes are thoroughly deresined products (1.5–3% resins) with high viscosities (30–45 cSt at 100°C) and carbon residues (2–4%), as a result of increased recovery of high-viscosity paraffinic, naphthenic, and aromatic hydrocarbons and compounds from the reduced crudes. 3. When the adsorption-deasphalted oils are further treated with a moving bed of adsorbent, light-colored deresined residual oils can be obtained in various viscosity levels (from aviation oils up to heavy bright stocks).