bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the Fibrillar and Microfibrillar Structure During Biomimetic Mineralization of Wood
Authors: Fritz‐Popovski Gerhard , Van Opdenbosch Daniel , Zollfrank Cordt , Aichmayer Barbara , Paris Oskar 
Published: October 2012

AbstractWood is a hierarchical composite, consisting at its lowest hierarchy level of crystalline cellulose elementary fibrils with diameters of 2–4 nm embedded in a matrix of hemicelluloses and lignin. At the micrometer scale, it has a cellular architecture resembling a honeycomb structure. The transformation of the hierarchical wood structure into a silica replica has been reported recently. Its formation process and structural details are studied in this contribution. First, a silica/biopolymer composite is prepared by wood delignification and cell‐wall modification, followed by silica precursor infiltration and condensation. The calcination process is monitored to gain insight into the structure development upon decomposition of the biopolymers. The material changes its architecture gradually from fibrillar structures of 10–20 nm in diameter with homogeneous electron density, into fibrils of 8–10 nm in diameter with inhomogeneous electron density, exhibiting internal sub‐fibrillar structures of about 2 nm in diameter. The steps of the successful replication of the cellulose elementary fibrils into nanopores of similar diameter and orientation in a fibrillar silica matrix are demonstrated. These nanopore replicas of the original cellulose are wound in a steep helix within the macropore walls. These advanced materials may have lightweight structural applications and the nanopores may be advantageous for molecular separation.
2‐Alkynylbenzaldehyde: A Versatile Building Block for the Generation of Cyclic Compounds
Authors: Wang Huanhuan , Kuang Yunyan , Wu Jie 
Published: October 2012

AbstractThe extensive use of cyclic compounds in many fields encourages the efficient construction of this class of compounds. Tandem reactions provide easy access to cyclic compounds because of their simple procedures, high efficiency, and superior atom economy. 2‐Alkynylbenzaldehyde is a versatile and powerful building block for generating functionalized polycyclic compounds, especially heterocycles, by tandem reactions. This Focus Review discusses recent advances in using 2‐alkynylbenzaldehydes as starting materials in the preparation of diverse and complex cyclic compounds. The progress that has been made provides important protocols for the design of more complex compounds and total syntheses of natural products.
Straightforward and Versatile Synthesis of Fullerooxazoles from C60 and Carboxamides through Radical Reactions under Mild Conditions
Authors: Takeda Youhei , Enokijima Satoru , Nagamachi Toshiki , Nakayama Kazuhisa , Minakata Satoshi 
Published: October 2012

AbstractA direct synthetic method for producing oxazoline‐fused fullerenes, that is, fullerooxazoles, from [60] fullerene and readily available carboxamides by radical pathways has been developed. The method presented allows efficient access to a variety of fullerooxazoles with high functional compatibility under mild reaction conditions. Furthermore, systematic investigation of their properties, such as solubility, thermostability, and electrochemical behavior, was conducted.
Natural selection and the origin and maintenance of standard genetic marker systems
Authors: Livingstone Frank B. 
Published: October 2012

AbstractNatural selection has always been assumed to be the major force of evolution, but its presence has been difficult to demonstrate. A review of the evidence for selective differences among genotypes for most human genetic polymorphisms indicates there is little of a direct nature. Indirect theoretical evidence, however, seems to support a major role for natural selection, and it does not seem to support the hypothesis that most amino acid substitutions within the human species are neutral. Among small isolates, most of the gene frequency differences are most likely due to genetic drift or the founder effect, and the principal counterbalancing force is gene flow or migration. But genetic differences among the major human subdivisions do not seem to be due to the same interacting forces. One reason for the inability to detect selection has been an oversimplified view of its operation, which assigns genotypes a constant fitness in every generation. Many recent theoretical developments of more complicated kinds of selection may lead to a resolution of the problem and suggest better interpretations of the enormous amount of data on human genetic variation that is rapidly accumulating.
Hominid paleoecology: The competitive exclusion principle and determinants of niche relationships
Authors: Winterhalder Bruce 
Published: October 2012

AbstractSome paleonanthropologists invoke the competitive exclusion principle programmatically in support of a single‐species (or lineage) hypothesis of hominid evolution. Others apparently accept the association between competitive exclusion and a single species view, and develop multi‐species interpretations using only taxonomic concepts. This paper demonstrates that the competitive exclusion principle itself is too assumption‐bound to be appropriate for analyzing questions of hominid coexistence. Especially, the principle does not establish the ecological validity of the single‐species hypothesis. Contrary to its immediate appearances, the principle has developed historically and analytically to predict and explain the evolution and maintenance of diversity in communities. Used in this manner it constitutes an important basis for the study of hominid paleoecology. Niche concepts necessary to demonstrate this are introduced, and competition and other factors that may have influenced the realized niches of sympatric hominid species are discussed. Nearly all modifications of the competitive exclusion principle that make it more realistic also illuminate factors that generate stable coexistence among competing species. These factors and their organizing theory establish the relevance of a broad data base to the analysis of hominid paleoecology; they should help to guide research on the ecology of early homonid species and their interrelationships.
Hominid brain evolution: The approach from paleoneurology
Authors: Falk Dean 
Published: October 2012

AbstractThe recent literature on hominid paleoneurology is reviewed and critically assessed. Two theoretical approaches for interpreting hominid paleoneurological data are discussed: (1) identifying cerebral “rubicons” that theoretically distinguish hominids from other primates and (2) analyzing brain evolution in terms of “residual” encephalization factors that remain after body size factors have been accounted for. Although these two approaches are scientific, much of the literature on human brain evolution is speculative—i.e., based on efforts to identify “prime movers,” such as hunting or warfare, that theoretically were responsible for the marked increase in both absolute and relative brain size that occurred during hominid evolution. The search for rubicons has been unfruitful. Features that distinguish hominid from pongid brains seem to be the result of allometry (i.e., determined by brain size) rather than the result of selection for qualitatively different neurological features. However, this finding may simply reflect the crude nature of the paleoneurological evidence. Thus, the field of comparative neurology is more likely than paleoneurology to contribute to our knowledge of the details of human brain evolution.
Nutritional status and physical work capacity
Authors: Spurr G. B. 
Published: October 2012

AbstractThe functional consequences of nutritional intake and resulting nutritional status are reviewed in terms of maximal oxygen consumption, physical work capacity, heart rate response to exercise, work productivity, and endurance at submaximal work loads. The results of both acute “laboratory” and chronic “naturally occurring” malnutrition are considered as well as the effects of dietary supplementation and recovery from previously existing undernutrition. Obesity and anemia are also treated as separate but related nutritional entities.
Genetic and familial factors in essential hypertension and related traits
Authors: Siervogel Roger M. 
Published: October 2012

AbstractThe health significance of essential hypertension “high blood pressure of undefined origin” is well established. It is a major factor contributing to coronary heart disease, stroke, and kidney failure. It directly affects about one in five Americans. Factors which are known to be associated with blood pressure include: body composition as it relates to overall mass and fat mass; physiological variables involving the sympathetic and parasympathetic nervous systems; biochemical variables such as renin, aldosterone, kallikrein, lipids, and lipoproteins, etc.; environmental variables such as sodium intake, heavy metals, and noise; and psychological variables involving personality type and mental stress.There is a definite, well‐established genetic involvement in hypertension, but specific genetic mechanisms remain a mystery. Familial aggregation occurs for many of the associated traits listed above. For some, specific polymorphic major genes have been identified, but for others genetic factors are unidentified. Essential hypertension is undoubtedly a heterogeneous group of diseases with the common end result of elevated blood pressure. Because of its health significance, there is considerable interest in identifying genetic mechanisms resulting in essential hypertension. One area that currently shows some potential for the identification of a specific genetic mechanism is related to the transmembrane transport of sodium and potassium cations.
Fetal growth as measured by ultrasound
Authors: Cronk Christine E. 
Published: October 2012

AbstractUntil the last decade, investigation of fetal growth has been based on data from premature births and abortuses. Advances in ultrasound scanning have expanded the precision and uses of this technology in studies of fetal growth. Most ultrasound studies of fetal growth are based on clinical populations and are reported in clinical journals. The present paper reviews features of ultrasound technology relating to fetal measurement. The most commonly measured dimensions and their associated measurement errors, distributions and uses are detailed. Ultrasound studies of intrauterine growth retardation and in utero fetal weight estimation are critically reviewed. Finally, a comparison between the fetal growth curve based on ultrasound measurement and on data from preterm or aborted fetuses is compared. Critical comments on sample design and statistical treatment of the data from ultrasound studies is included in each of the areas discussed.
Dominance and reproductive success in primates
Authors: Fedigan Linda Marie 
Published: October 2012

AbstractTheoretical models of the relationship between competition and differential reproduction in primates share the premise that agonistic dominance hierarchies determine differential access to those limited resources which are essential to reproduction. In particular, the priority‐of‐access‐to‐estrous‐female model is based on the postulate that high rank in males enhances reproductive success. Tests for a correlation between rank and reproductive success in males have produced mixed results. Problems in measuring male reproductive success and in conceptualizing dominance systems are implicated in the diversity of conclusions reached. Other attributes which affect reproductive success have been proposed, and alternative models of mating systems, based on the concepts of reproductive strategies, social skills, and life histories have also been developed.Studies of differential reproduction in female primates are fewer, but have the advantage over male studies of directly measuring infant production and offspring survival. Research on the relationship between rank and reproductive success in females has shown that under conditions of low resource availability, subordinate females sometimes suffer reduced fecundity and infant survival as a result of restricted access to food and water. Under conditions of social stress, low‐ranking females may suffer from disruption of their reproductive cycles, resulting in lowered fecundity. Dominant females may also incur reproductive costs as well as benefits for their social position.Better insights into the relationship between dominance and reproduction are potentially offered by improved genetic paternity measures, new models of social and demographic processes, and the recent availability of life history data from field studies.
The genetics of human fatness
Authors: Mueller William H. 
Published: October 2012

AbstractStudies on the quantitative genetics of fatness are reviewed in the framework of the twin, adoption‐cohabitation, and familial aggregation methodologies. Low to moderate heritability of adult static fatness is evident. Somewhat less than one‐third of the variation appears ascribable to genetic causes. Genetic factors may play a greater role in childhood fatness, especially during adolescence. Comparison of studies is made difficult by many methodological shortcomings. These include a rarity of studies of adult first‐degree relatives “adulthood being the period in which fatness has the greatest health consequences”, different criteria of body fatness among studies, a lack of a full variety of genetic and adoptive relationships, inadequate sample sizes “especially in twin studies”, and unreported precision of fatness variables. Fatness change in the life cycle and the anatomical placement of fat are important modifiers of the health effects of obesity. Yet the genetics of these characteristics are little understood. Innovative statistical methods and study designs including path analysis, the family set method, and families of monozygous twins need wider application to the genetics of human fatness.
Thermal decomposition studies of Schiff‐base‐substitute polyphenol–metal complexes
Authors: Doğan Fatih , Kaya İsmet 
Published: October 2012

AbstractThe thermal behaviors of 2,3‐bis[(2‐hydroxyphenyl)methylene] diaminopyridine, oligo‐2,3‐bis[(2‐hydroxyphenyl)methylene] diaminopyridine, and some oligo‐2,3‐bis[(2‐hydroxyphenyl) methylene] diaminopyridine–metal complexes were studied in a nitrogen atmosphere with thermogravimetric analysis, derivative thermogravimetric analysis, and differential thermal analysis techniques. The decompositions of oligo‐2,3‐bis[(2‐hydroxyphenyl) methylene] diamino pyridine–metal complexes occurred in multiple steps. The values of the activation energy (E) and reaction order of the thermal decomposition were calculated by means of several methods, including Coats–Redfern, Horowitz–Metzger, Madhusudanan–Krishnan–Ninan, van Krevelen, Wanjun–Yuwen–Hen–Cunxin, and MacCallum–Tanner on the basis of a single heating rate. The most appropriate method was determined for each decomposition step according to a least‐squares linear regression. The E values obtained by each method were in good agreement with each other. It was found that the E values of the complexes for the first decomposition stage followed the order EOHPMDAP–Ni > EOHPMDAP–Cd > EOHPMDAP–Cu > EOHPMDAP–Fe > EOHPMDAP–Zn > EOHPMDAP–Co > EOHPMDAP–Cr > EHPMDAP > EOHPMDAP. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Mechanical properties of silane‐treated silica particle‐filled polyisoprene composites: Influence of the alkoxy group mixing ratio in silane coupling agent containing mercapto group
Authors: Nakamura Yoshinobu , Nishida Yuji , Fukuda Tomoyoshi , Fujii Syuji , Sasaki Mariko 
Published: October 2012

AbstractSpherical silica particles were treated with a mixture of silane coupling agents with mercapto functional groups and dialkoxy or trialkoxy groups. The surface coverage, which indicates the number of layers covering the silica surface, was in the range from 1.6 to 6.0. The molecular mobility of the treated layer was analyzed with 1H‐NMR spectroscopy. The silane chain became more flexible with increasing dialkoxy structures in the mixture and with increasing surface coverage. The stress–strain behavior was measured for a composite consisting of the treated silica and vulcanized polyisoprene rubber (PIR). There was no influence of the dialkoxy and trialkoxy mixing ratio for near monolayer coverage. In the case of the pure dialkoxy and low trialkoxy contents, a higher stress was observed at the same strain for surface coverages of 2.4–3.8. However, a longer length flexible silane chain, that is, with a surface coverage of 6.0, was disadvantageous for the reinforcement effect. The results of pulse NMR analysis of the unextracted PIR on the particle surface and swelling test indicate that the reinforcement effect was strongly affected both by entanglement and the crosslinking reaction between the silane chain and PIR at the interfacial region. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Gas permeation and separation properties of polyimide/ZSM‐5 zeolite composite membranes containing liquid sulfolane
Authors: Kanehashi Shinji , Gu Hua , Shindo Ryohei , Sato Shuichi , Miyakoshi Tetsuo , Nagai Kazukiyo 
Published: October 2012

AbstractThe preparation, characterization, and gas permeation properties of novel composite membranes containing polyimide (PI), liquid sulfolane (SF), and zeolite (ZSM‐5) were investigated to address the interface defects between the PI and the zeolite. The free‐standing composite membranes were prepared by the solvent casting method. The gas permeability of the PI+ZSM‐5 membrane was higher than that of PI, whereas its gas selectivity was significantly reduced, suggesting that these results are attributed to the interface defects. The CO2 selectivity of PI+ZSM‐5+SF was higher than those of the PI+ZSM‐5 membranes because of the introduction of liquid SF into the interface defects. Furthermore, liquid SF enhanced the CO2/H2 selectivity near the recent upper bound. Therefore, the use of liquid SF could be an effective approach to preventing interface defects and increasing the CO2 selectivity, particularly for CO2/H2. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
A new method for stabilizing softwood kraft lignin fibers for carbon fiber production
Authors: Norberg Ida , Nordström Ylva , Drougge Rickard , Gellerstedt Göran , Sjöholm Elisabeth 
Published: October 2012

AbstractRenewable resources, such as kraft lignin, have shown great potential as precursors for carbon fiber production. This manuscript reports an investigation into the stabilization of softwood kraft lignin (SKL) fibers and the determination of the difference in stabilization between hardwood‐ and softwood‐based kraft lignin fibers. The stabilization was achieved either thermally by using only heat or oxidatively in the presence of air, at various heating rates. A heating rate of 4°C min−1 and a holding time of 30 min at 250°C were successfully used for the thermal stabilization experiments. Faster stabilization was achieved using oxidative conditions at a heating rate of 15°C min−1 and 30 min holding time at 250°C. Furthermore, stabilization and carbonization in a one‐step process was performed on SKL fibers, which show great potential to reduce both production time and costs. The stabilized and carbonized fibers were evaluated using thermal, spectroscopic, and microscopic methods. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Lanolin‐based organogels as a matrix for topical drug delivery
Authors: Sagiri Sai Sateesh , Behera Beauty , Pal Kunal , Basak Piyali 
Published: October 2012

AbstractThe current study deals with the development of lanolin‐based emulsion gels by hot emulsification method. Bright‐field, phase contrast, and fluorescent micrographs of the gels have shown the uniform distribution of circular water droplets in the formulations. Coalescence of water droplets was observed in gels containing higher proportion of water. Fourier transform infrared spectrophotometric studies indicated absence of Ln‐drug chemical interactions. X‐ray diffraction studies suggested an increase in amorphousness of the gels with the incorporation of water into the gel structure. The salicylic acid (SA), model drug, release from the gels was found to follow Higuchi kinetics. Krossmeyer–Peppas model fitting indicated non‐Fickian release of the drug. As the water content of the gels increased, there was a corresponding increase in the rate of release of the drug. The gels showed non‐Newtonian and thixotropic flow behavior. The gel to sol transition and melting temperatures of the gels were identified by differential scanning calorimetric (DSC) thermal analysis and falling ball method. DSC thermograms indicated an increase in thermal stability with the increase of water content in the gels. The gels showed sufficient spreadability and biocompatibility characteristics to be used as topical formulations. SA loaded gels showed good antimicrobial efficacy against Bacillus subtilis, a Gram‐positive bacterium. Based on the preliminary studies, the developed gels may be regarded as carriers in topical drug delivery. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Electrical properties of sorbitol‐doped poly(vinyl alcohol)–poly(acrylamide‐co‐acrylic acid) polymer membranes
Authors: Josh Vinitha , Haik Mohammad Y. , Ayesh Ahmad I. , Mohsin Mahmoud A. , Haik Yousef 
Published: October 2012

AbstractSolid polymer membranes from poly(vinyl alcohol) (PVA) and poly(acrylamide‐co‐acrylic acid) (PAA) with varying doping ratios of sorbitol were prepared using the solution casting method. The films were examined with Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and AC impedance spectroscopy. The impedance measurements showed that the ionic conductivity of PVA–PAA polymer membrane can be controlled by controlled doping of sorbitol within the polymer blends. The PVA–PAA–sorbitol membranes were found to exhibit excellent thermal properties and were stable for a wide temperature range (398–563K), which creates a possibility of using them as suitable polymers for device applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effect of polymer matrix/montmorillonite compatibility on morphology and melt rheology of polypropylene nanocomposites
Authors: Zhu Shipeng , Chen Jinyao , Li Huilin , Cao Ya 
Published: October 2012

AbstractIn this study, Ca2+‐montmorillonite (Ca2+‐MMT) and organo‐montmorillonite (OMMT) were modified by three compatibilizers with different degrees of polarity [poly(ethylene glycol) (PEG), alkyl‐PEG, and polypropylene (PP)‐g‐PEG]. PP/MMT nanocomposites were prepared by melt blending and characterized using X‐ray diffraction and transmission electron microscopy. The results showed the degree of dispersion of OMMT in the PP/PP‐g‐PEG/OMMT (PMOM) nanocomposite was considerably higher than those in the PP/PEG/OMMT and PP/alkyl‐PEG/OMMT nanocomposites, which indicated that the dispersion was relative to the compatibility between modified OMMT and PP matrix. Linear viscoelasticity of PP/MMT nanocomposites in melt states was investigated by small amplitude dynamic rheology measurements. With the addition of the modified MMT, the shear viscosities and storage modulus of all the PP/MMT nanocomposites decreased. It can be attributed to the plasticization effect of PEG segments in the three modifiers. This rheological behavior was different from most surfactant modified MMT nanocomposites which typically showed an increase in dynamic modulus and viscosity relative to the polymer matrix. The unusual rheological observations were explained in terms of the compatibility between the polymer matrix and MMT. In addition, the mechanical properties of PP/MMT nanocomposites were improved. A simultaneous increase in the tensile strength and toughness was observed in PP/PMOM nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013