bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical and thermal properties of calcium carbonate‐filled PP/LLDPE composite
Authors: Ghalia Mustafa Abu , Hassan Azman , Yussuf Abdirahman
Published: March 2011

Polymer blends typically are the most economical means to develop new resins for specific applications with the best cost/performance balance. In this paper, the mechanical properties, melting, glass transition, and crystallization behavoir of 80 phr polypropylene (PP) with varying weights of linear low density polyethylene (LLDPE) at 10, 20/ 20 wt % CaCO3, 30, 40, and 50 phr were studied. A variety of physical properties such as tensile strength, impact strength, and flexural strength of these blends were evaluated. The compatibility of these composite was examined by differential scanning calorimetry (DSC) to estimate Tm and Tc, and by dynamic mechanical analysis (DMA) to estimate Tg. The fractographic analysis of these blends was examined by scanning electron microscopy (SEM). It has been confirmed that increasing the LLDPE content trends to decreases the tensile strength and flexural strength. However, increasing the LLDPE content led to increases in the impact strength of PP/LLDPE blends. It was also found that up to 40 phr the corresponding melting point (Tm) was not effected with increasing LLDPE content. Each compound has more than one Tg, which was informed that there is a brittle‐ductile transition in fracture nature of these blends, the amount of material plastically deformed on the failure surface seems to increase with the increasing the LLDPE content. And PP/LLDPE blends at temperature (23°C) showed a ductile fracture mode characterized by the co‐existence of a shear yielding process; whereas at lower temperature (−20°C) the fractured surfaces of specimens appear completely brittle. The specimens broke into two pieces with no evidence of stress whitening, permanent macroscopic deformation or yielding. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Studies of organoclays with functionalized pillaring agents
Authors: Zhang Yongcheng , Pittman Charles U. , Arockiasamy Antonyraj , King Roger L.
Published: March 2011

A series of clay pillaring agents with amino, olefin, and epoxy groups were synthesized. These pillaring agents were used to modify montmorillonite clay by ion‐exchange reactions. TGA studies showed that organoclays with imidazolium pillaring agents have a higher thermal stability than those with ammonium groups. The d‐spacings of organoclays were not affected by the pillaring agent functional groups and were sensitive to the size of pillaring agents. The dynamic‐mechanical properties of the resulting clay/epoxy composites determined by DMA were similar. The addition of these clays to this epoxy resin enhanced the Tg value of the resulting composites and greatly enhanced the storage moduli versus the pure epoxy resin by 1.6–1.8 times at 135°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Impact behavior and fracture morphology of acrylonitrile–butadiene–styrene resins toughened by linear random styrene–isoprene–butadiene rubber
Authors: Yang Juan , Wang Chao‐Xian , Yu Zhi‐Sheng , Li Yang , Yang Ke‐Ke , Wang Yu‐Zhong
Published: March 2011

A novel toughening modifier, styrene–isoprene–butadiene rubber (SIBR), was used to improve the impact resistance and toughness of acrylonitrile–butadiene–styrene (ABS) resin via bulk polymerization. For comparison, two kinds of ABS samples were prepared: ABS‐1 was toughened by a conventional modifier (a low‐cis polybutadiene rubber/styrene–butadiene block copolymer), and ABS‐2 was toughened by SIBR. The mechanical properties, microstructures of the as‐prepared materials, and fracture surface morphology of the specimens after impact were studied by instrumented notched Izod impact tests and tensile tests, transmission electron microscopy, and scanning electron microscopy, respectively. The mechanical test results show that ABS‐2 had a much higher impact strength and elongation at break than ABS‐1. The microscopic results suggested that fracture resistance of ABS‐1 only depended on voids, shear yielding, and few crazing, which resulted in less ductile fracture behavior. Compared with ABS‐1, ABS toughened by linear random SIBR (ABS‐2) displayed the synergistic toughening effect of crazing and shear yielding, which could absorb and dissipate massive energy, and presented high ductile fracture behavior. These results were also confirmed by instrumented impact tests. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Intramolecular and intermolecular crosslinked poly(vinyl alcohol)–borate complexes for the sustained release of fertilizers and enzymes
Authors: Kale S. N. , Mona J. , Dhobale Sandip , Thite Trupti , Laware S. L.
Published: March 2011

Therapeutic agents or agricultural fertilizers captured in polymer colloids (PCs) give rise to interesting applications, which are typically related to sustained release. We synthesized crosslinked polymer structures with poly(vinyl alcohol) (PVA) and borax precursors. Fourier transform infrared spectroscopy showed that a polymer–boron ion complex was formed with the crosslinking reaction at the OH site of PVA; thereby, PCs were formed. Field‐emission scanning electron microscopy showed that a uniform mesoporous two‐dimensional structure formed via intermolecular and intramolecular crosslinking. Trypsin enzyme and phosphate fertilizer were trapped in these PCs independently to study sustained release. Fertilizer‐incorporated PCs were mixed with soil samples, in which seeds of fenugreek were sown, and the plant growth was monitored a duration of 15 days. The fertilizer release, studied with UV–visible spectroscopy, showed a sustained signature of the fertilizer (at 690 nm) in the water extracts of soil, with much healthier plant growth compared to the control. For the trypsin‐incorporated PC samples, the released enzyme was made to interact with bovine serum albumin protein to monitor the released percentage with UV absorption spectroscopy. A systematic increase in the enzyme signature (at 280 nm) was observed for a duration of 60 min; this indicated the potential of PC for sustained drug release. The swelling calculations predicted that the mechanism involved was composed of pseudo‐swelling behavior. We envisaged that the hydroxyl groups of the PC broke in water and formed a complex with water. This complex slowly dissolved in water to release the entrapped molecules. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and characterization of porous poly(N‐isopropylacrylamide) hydrogels prepared in ethanol–water mixtures
Authors: Biswas Chandra Sekhar , Patel Vijay Kumar , Vishwakarma Niraj Kumar , Mishra Avnish Kumar , Ray Biswajit
Published: March 2011

Poly(N‐isopropylacrylamide) (PNIPAM) hydrogels were prepared by free‐radical polymerization in different ethanol–water mixtures. A scanning electron microscopy study revealed that the resulting hydrogels were macroporous. The swelling ratios of the resultant hydrogels in water at 20°C followed this order: X0.34 ≈ X0.68 > X0.48 > X0.09 > X0.04 > X0, where Xa denotes a gel prepared in an ethanol–water solvent mixture with an ethanol molar fraction of a. Below the lower critical solution temperature, the swelling ratio values of all of the hydrogels gradually decreased with increasing temperature. The complete collapse of the PNIPAM chain of all of these gels occurred at about 38°C, whereas the same was observed at about 35°C for the conventional gel prepared in water. The swelling ratio values of all of the PNIPAM gels with different molar fractions of ethanol at 20°C passed through a minimum in the cononsolvency zone. The deswelling rates of the hydrogels decreased in the following order: X0.34 > X0.48 > X0.68 > X 0.09 > X0.04 > X0. The reswelling rates of these hydrogels decreased in the following order: X0 > X0.04 ≈ X0.48 > X0.09 ≈ X0.68 > X 0.34. The freeze‐drying process decreased the swelling ratios but increased the deswelling and reswelling properties of the PNIPAM gels. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Effect of the solvent type on the formation and physical properties of polyacrylonitrile fibers via a solvent‐free coagulation bath
Authors: Mahmod D. S. A. , Ismail A. F. , Mustafa A. , Ng B. C. , Abdullah M. S.
Published: March 2011

Polyacrylonitrile (PAN) fibers were fabricated via a dry‐jet wet‐spinning technique, and a solvent‐free coagulation bath system was adopted. The effects of different types of dope solvent on the formation and physical properties of the PAN fibers were investigated. Dimethylformamide and dimethyl sulfoxide (DMSO) were selected as the solvents and were added to a spinning solution consisting of 18 wt % PAN. The PAN fibers were examined with field emission scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis. The field emission scanning electron micrographs revealed that the PAN fibers with the DMSO solvent exhibited a more circular shape and a smoother skin. The PAN fibers with the DMSO solvent had their glass‐transition temperature (Tg) at 121°C. This study indicated that the different types of dope solvent used in the dope preparation did not affect Tg of the PAN fibers because of the solvent‐free coagulation bath system; however, they significantly affected the physical formation of the PAN fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Emulsion copolymerization of tetrafluoroethylene with ω‐chlorotetrafluoroethyltrifluorovinyl ether and the synthesized copolymer properties
Authors: Allayarov S. R. , Ilyin A. N. , Olkhov Yu. A. , Allayarova U. Yu. , Dixon D. A.
Published: March 2011

Emulsion copolymerization of ω‐chlorotetrafluoroethyltrifluorovinyl ether (Cl(CF2)2OCF = CF2 (FVE)) with tetrafluoroethylene (CF2 = CF2 (TFE)) was investigated at various monomer ratios. The copolymerization rate is below the rate of TFE homopolymerization and the copolymerization kinetics depends on the FVE content in the reaction medium. The copolymer composition is very similar if the FVE content in monomer mixture is ≤2.5 mol %. However, the percent amount of FVE in the copolymer, the copolymerization rate, and molecular mass of synthesized copolymers decrease noticeably with increase in the FVE content in the monomer mixture. The constants of copolymerization are r1= 2.8 (TFE) and r2 = 0.03 (FVE). The copolymer is a statistical polymer consisting of TFE blocks and individual FVE molecules between the blocks. The average molecular mass of copolymers is significantly less than that of the TFE homopolymer (PTFE) synthesized at the same conditions. The morphologies of PTFE and copolymer powders were investigated by thermomechanical analysis and are not similar. The copolymer has a completely amorphous diblock morphology depending on the FVE content. The introduction of FVE molecules into the copolymer macromolecules is accompanied by reduction of the crystalline portion of copolymer. If the FVE content in copolymer is ≥3.5 mol %, the copolymer macromolecules completely lose the ability to form crystalline portions as a result of their amorphicity. The introduction of up to 2.4 mol % FVE into the copolymer macromolecules yields a highly thermostable and meltable copolymer which can be processed by using the industrial processes used widely for thermoplastics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
The thermal conductivity of fir and beech wood heat treated at 170, 180, 190, 200, and 212°C
Authors: Kol Hamiyet Şahin , Sefil Yusuf
Published: March 2011

Heat treatment changes the chemical, physical, and mechanical properties of wood. The properties of heat‐treated wood have been researched considerably, but the thermal conductivity of heat‐treated wood in various conditions has not been reported. In this study, the thermal conductivity of heat‐treated fir and beech wood at temperatures 170, 180, 190, and 212°C for 2 h with ThermoWood method were investigated. The results were compared with industrially kiln‐dried reference samples. The results show that heat treatment caused an important reduction on thermal conductivity of wood, the extend of which is depend upon temperature and wood species. Considering all heat treating temperatures, generally by increasing heat treatment temperature the thermal conductivity of wood decreased. The effect of heat treating temperature on thermal conductivity was identical for fir and beech wood. The highest decrease in thermal conductivity occurred at 212°C for both wood species. When compared with untreated wood, the decreases in thermal conductivity at 170°C, and 212°C for fir and beech wood were 2%, 9 and 2%, 16% respectively. Depending on heat treatment temperature, the decrease found out beech in high temperature is higher than that of fir. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Curing kinetics of fluorene containing benzoxazine investigated by nonisothermal differential scanning calorimetry
Authors: Lu Yanbing , Li Mingming , Ke Lili , Hu Ding , Xu Weijian
Published: March 2011

Fluorene containing benzoxazine monomer (B‐pbf) was synthesized from 9, 9‐bis(4‐hydroxyphenyl) fluorene, aniline, and paraformaldehyde via a solution method. The chemical structure of B‐pbf was characterized with FTIR and 1H‐NMR. The curing reaction of B‐pbf was investigated by nonisothermal differential scanning calorimetry (DSC) at different heating rates. The kinetic parameters and the kinetic models of the curing processes were examined utilizing Kissinger, Ozawa, Flynn‐Wall‐Ozawa, and Friedman methods. The average activation energy of the curing reaction was determined to be 95.1 kJ mol−1 and 99.0 kJ mol−1, respectively, according to Kissinger and Ozawa method. The autocatalytic kinetic model was found to be the best description of the investigated curing reaction. The reaction order m and n are 0.95 and 2.03, respectively. In addition, the predicted curves from the kinetic models fit well with the nonisothermal DSC thermograms. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Epigenetic programming: From gametes to blastocyst
Authors: Hales Barbara F. , Grenier Lisanne , Lalancette Claudia , Robaire Bernard
Published: March 2011

Embryo development requires a series of cell fate decisions; cell lineages are established early during development and must be “remembered” through multiple cell divisions. It is increasingly evident that epigenetic marks, DNA methylation, histone modifications, and noncoding RNAs, have a critical role in this cell memory during development. During gametogenesis, epigenetic programming results in the production of spermatozoa and oocytes with distinctive chromatin. The goal of this article is to review what is known about the epigenetic marks in mature gametes and how these marks change during early embryo development. An understanding of the role of epigenetic programming during normal development will lay the basis for the elucidation of its role when development goes awry and the consequence is a birth defect. Birth Defects Research (Part A) 2011. © 2011 Wiley‐Liss, Inc.
Expression patterns of placental microRNAs
Authors: Mouillet Jean–Francois , Chu Tianjiao , Sadovsky Yoel
Published: March 2011

Among different types of small RNA molecules, distinct types of microRNAs (miRNAs) are expressed in many cell types, where they modulate RNA stability and translation, thus controlling virtually every aspect of tissue development, proliferation, differentiation, and function. Aberrant miRNA expression has been linked to discrete pathologic processes. As the placenta plays a pivotal role in governing fetal development, it is not surprising that the placenta expresses numerous types of miRNAs. Whereas many of these miRNAs are ubiquitously expressed, certain miRNA species are largely unique to the placenta. Research in the field of placental miRNAs is in its early phase, with most studies centering on cataloging placental miRNA species or examining differences in placental miRNA expression between placentas from normal pregnancies and those from pregnancies complicated by pathologies that are associated with placental dysfunction. Recent research endeavors ventured to assess the function of miRNAs in cultured placental trophoblasts, using in vitro conditions that model relevant pathophysiological processes. The impact of miRNA‐mediated repression on the trophoblast transcriptome, particularly in response to genetic and environmental perturbations, remains largely unknown. Further indepth studies are required to unravel the functional significance of miRNAs in molding placental robustness, which must constantly adapt to altered maternal physiologic status to sustain optimal support to the developing embryo. In this review, we summarize the current information about placental miRNAs expression, and the lingering challenges in this field. Birth Defects Research (Part A) 2011. © 2011 Wiley‐Liss, Inc.
IUGR differentially alters MeCP2 expression and H3K9Me3 of the PPARγ gene in male and female rat lungs during alveolarization
Authors: Joss–Moore Lisa A. , Wang Yan , Ogata Elizabeth M. , Sainz Anthony J. , Yu Xing , Callaway Christopher W. , McKnight Robert A. , Albertine Kurt H. , Lane Robert H.
Published: March 2011

Intrauterine growth restriction (IUGR) increases the risk of postnatal lung disease, with males more affected. In rat lungs, IUGR impairs alveolarization in conjunction with altered expression of peroxisome proliferator‐activated receptor gamma (PPARγ). In non‐lung cells, PPARγ transcription is regulated in part by the epigenetic modifying enzyme, and the methyl CpG binding protein 2 (MeCP2). However, it is unknown if IUGR affects MeCP2 expression or its interaction with PPARγ in the rat lung during alveolarization. In this study, we hypothesized that the rat lung would be characterized by the presence of MeCP2 short and long mRNA transcripts, MeCP2 protein isoforms, and the MeCP2 regulatory micro RNA, miR132. We further hypothesized that IUGR would, in a gender‐specific manner, alter the levels of MeCP2 components in association with changes in PPARγ mRNA, MeCP2 occupancy at the PPARγ promoters, and PPARγ histone 3 lysine 9 trimethylation (H3K9Me3). To test these hypotheses, we used a well‐characterized rat model of uteroplacental insufficiency‐induced IUGR. We demonstrated the presence of MeCP2 mRNA, protein, and miR132 in the rat lung throughout alveolarization. We also demonstrated that IUGR alters MeCP2 expression and its interaction with PPARγ in a gender‐divergent manner. We conclude that IUGR induces gender‐specific alterations in the epigenetic milieu in the rat lung. We speculate that in the IUGR rat lung, this altered epigenetic milieu may predispose to gender‐specific alterations in alveolarization. Birth Defects Research (Part A) 2011. © 2011 Wiley‐Liss, Inc.
Symbiosis and development: The hologenome concept
Authors: Rosenberg Eugene , Zilber‐Rosenberg Ilana
Published: March 2011

All animals and plants establish symbiotic relationships with microorganisms; often the combined genetic information of the diverse microbiota exceeds that of the host. How the genetic wealth of the microbiota affects all aspects of the holobiont's (host plus all of its associated microorganisms) fitness (adaptation, survival, development, growth and reproduction) and evolution is reviewed, using selected coral, insect, squid, plant, and human/mouse published experimental results. The data are discussed within the framework of the hologenome theory of evolution, which demonstrates that changes in environmental parameters, for example, diet, can cause rapid changes in the diverse microbiota, which not only can benefit the holobiont in the short term but also can be transmitted to offspring and lead to long lasting cooperations. As acquired characteristics (microbes) are heritable, consideration of the holobiont as a unit of selection in evolution leads to neo‐Lamarckian principles within a Darwinian framework. The potential application of these principles can be seen in the growing fields of prebiotics and probiotics. Birth Defects Research (Part C) 93:56–66, 2011. © 2011 Wiley‐Liss, Inc.
Endocrine disrupting chemicals and the developmental programming of adipogenesis and obesity
Authors: Janesick Amanda , Blumberg Bruce
Published: March 2011

Obesity and related disorders are a burgeoning public health epidemic, particularly in the U.S. Currently 34% of the U.S. population is clinically obese (BMI > 30) and 68% are overweight (BMI > 25), more than double the worldwide average and 10‐fold higher than Japan and South Korea. Obesity occurs when energy intake exceeds energy expenditure; however, individuals vary widely in their propensity to gain weight and accrue fat mass, even at identical levels of excess caloric input. Clinical, epidemiological, and biological studies show that obesity is largely programmed during early life, including the intrauterine period. The environmental obesogen hypothesis holds that prenatal or early life exposure to certain endocrine disrupting chemicals can predispose exposed individuals to increased fat mass and obesity. Obesogen exposure can alter the epigenome of multipotent stromal stem cells, biasing them toward the adipocyte lineage at the expense of bone. Hence, humans exposed to obesogens during early life might have an altered stem cell compartment, which is preprogrammed toward an adipogenic fate. This results in a higher steady state number of adipocytes and potentially a lifelong struggle to maintain a healthy weight, which can be exacerbated by societal influences that promote poor diet and inadequate exercise. This review focuses on the developmental origins of the adipocyte, the relationship between adipocyte number and obesity, and how obesogenic chemicals may interfere with the highly efficient homeostatic mechanisms regulating adipocyte number and energy balance. Birth Defects Research (Part C) 93:34–50, 2011. © 2011 Wiley‐Liss, Inc.
The role of developmental plasticity and epigenetics in human health
Authors: Gluckman Peter D. , Hanson Mark A. , Low Felicia M.
Published: March 2011

Considerable epidemiological, experimental and clinical data have amassed showing that the risk of developing disease in later life is dependent on early life conditions, mainly operating within the normative range of developmental exposures. This relationship reflects plastic responses made by the developing organism as an evolved strategy to cope with immediate or predicted circumstances, to maximize fitness in the context of the range of environments potentially faced. There is now increasing evidence, both in animals and humans, that such developmental plasticity is mediated in part by epigenetic mechanisms. However, recognition of the importance of developmental plasticity as an important factor in influencing later life health—particularly within the medical and public health communities—is low, and we argue that this indifference cannot be sustained in light of the growing understanding of developmental processes and the rapid rise in the prevalence of obesity and metabolic disease globally. Birth Defects Research (Part C) 93:12–18, 2011. © 2011 Wiley‐Liss, Inc.
Role of epigenetics in developmental biology and transgenerational inheritance
Authors: Skinner Michael K.
Published: March 2011

The molecular mechanisms involved in developmental biology and cellular differentiation have traditionally been considered to be primarily genetic. Environmental factors that influence early life critical windows of development generally do not have the capacity to modify genome sequence, nor promote permanent genetic modifications. Epigenetics provides a molecular mechanism for environment to influence development, program cellular differentiation, and alter the genetic regulation of development. The current review discusses how epigenetics can cooperate with genetics to regulate development and allow for greater plasticity in response to environmental influences. This impacts area such as cellular differentiation, tissue development, environmental induced disease etiology, epigenetic transgenerational inheritance, and the general systems biology of organisms and evolution. Birth Defects Research (Part C) 93:51–55, 2011. © 2011 Wiley‐Liss, Inc.
The effects of alcohol on fetal development
Authors: Jones Kenneth Lyons
Published: March 2011

Prenatal exposure to alcohol has profound effects on many aspects of fetal development. Although alterations of somatic growth and specific minor malformations of facial structure are most characteristic, the effects of alcohol on brain development are most significant in that they lead to substantial problems with neurobehavioral development. Since the initial recognition of the fetal alcohol syndrome (FAS), a number of important observations have been made from studies involving both humans and animals. Of particular importance, a number of maternal risk factors have been identified, which may well be of relevance relative to the development of strategies for prevention of the FAS as well as intervention for those who have been affected. These include maternal age >30 years, ethnic group, lower socioeconomic status, having had a previously affected child, maternal under‐nutrition, and genetic background. The purpose of this review is to discuss these issues as well as to set forth a number of questions that have not adequately been addressed relative to alcohol's effect on fetal development. Of particular importance is the critical need to identify the full spectrum of structural defects associated with the prenatal effects of alcohol as well as to establish a neurobehavioral phenotype. Appreciation of both of these issues is necessary to understand the full impact of alcohol on fetal development. Birth Defects Research (Part C) 93:3–11, 2011. © 2011 Wiley‐Liss, Inc.
Epigenetics and the brain: Transcriptome sequencing reveals new depths to genomic imprinting
Authors: Kelsey Gavin
Published: March 2011

Transcriptome sequencing has identified more than a thousand potentially imprinted genes in the mouse brain. This comes as a revelation to someone who cut his teeth on the identification of imprinted genes when only a handful was known. Genomic imprinting, an epigenetic mechanism that determines expression of alleles according to sex of transmitting parent, was discovered over 25 years ago in mice but remains an enigmatic phenomenon. Why do these genes disobey the normal Mendelian logic of inheritance, do they function in specific processes, and how is their imprinting conferred? Next generation sequencing technologies are providing an unprecedented opportunity to survey the whole genome for imprinted genes and are beginning to reveal that imprinting may be more pervasive than we had come to believe. Such advances should lay the foundation for a definitive account of imprinting, but may also challenge accepted views on what it means to be imprinted.

Editor's suggested further reading in BioEssays RNA as the substrate for epigenome‐environment interactions Abstract
Nucleolar aggresomes as counterparts of cytoplasmic aggresomes in proteotoxic stress
Authors: Latonen Leena
Published: March 2011

The nucleolus may represent a key stress response organelle in the nucleus following proteotoxic stress by serving as a platform for protein aggregates. Aggregation of proteins often results from insufficient protein degradation by the ubiquitin‐proteasome system (UPS), occurring in inclusion diseases, upon treatment by proteasome inhibitors (PIs) or due to various forms of stress. As the nucleolar inclusions resemble cytoplasmic aggresomes in gathering ubiquitin and numerous UPS components and targets, including cancer‐related transcription factors and cell cycle regulators (e.g. p53 and cyclin D) and proteins involved in neurodegenerative diseases (e.g. ataxin‐1, Malin), these organelles are termed herein as nucleolar aggresomes. These nucleolar aggresomes contain polyadenylated RNA, and seem to be linked to defects in nuclear export. Nucleolar aggresomes have been identified in non‐neuronal cells, but prominent similarities with nuclear ubiquitin and/or ribonuclear foci detected in triplet and other repeat disease pathologies are revealed here, creating a common interest between research in cancer and neurodegeneration.
Selectivity and delignification kinetics for oxidative short‐term lime pretreatment of poplar wood, part I: Constant‐pressure
Authors: Sierra‐Ramírez Rocío , Garcia Laura A. , Holtzapple Mark Thomas
Published: March 2011

Kinetic models applied to oxygen bleaching of paper pulp focus on the degradation of polymers, either lignin or carbohydrates. Traditionally, they separately model different moieties that degrade at three different rates: rapid, medium, and slow. These models were successfully applied to lignin and carbohydrate degradation of poplar wood submitted to oxidative pretreatment with lime at the following conditions: temperature 110–180°C, total pressure 7.9–21.7 bar, and excess lime loading of 0.5 g Ca(OH)2 per gram dry biomass. These conditions were held constant for 1–6 h. The models properly fit experimental data and were used to determine pretreatment selectivity in two fashions: differential and integral. By assessing selectivity, the detrimental effect of pretreatment on carbohydrates at high temperatures and at low lignin content was determined. The models can be used to identify pretreatment conditions that selectively remove lignin while preserving carbohydrates. Lignin removal ≥50% with glucan preservation ≥90% was observed for differential glucan selectivities between ∼10 and ∼30 g lignin degraded per gram glucan degraded. Pretreatment conditions complying with these reference values were preferably observed at 140°C, total pressure ≥14.7 bars, and for pretreatment times between 2 and 6 h depending on the total pressure (the higher the pressure, the less time). They were also observed at 160°C, total pressure of 14.7 and 21.7 bars, and pretreatment time of 2 h. Generally, at 110°C lignin removal is insufficient and at 180°C carbohydrates do not preserve well. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Efficient suspension bioreactor expansion of murine embryonic stem cells on microcarriers in serum‐free medium
Authors: Alfred Roz , Radford Jaret , Fan Jessica , Boon Kathryn , Krawetz Roman , Rancourt Derrick , Kallos Michael S.
Published: March 2011

Large numbers of cells will be required for successful embryonic stem cell (ESC)‐based cellular therapies or drug discovery, thus raising the need to develop scaled‐up bioprocesses for production of ESCs and their derived progeny. Traditionally, ESCs have been propagated in adherent cultures in static flasks on fibroblasts layers in serum‐containing medium. Direct translation of two‐dimensional flatbed cultures to large‐scale production of the quantities of cells required for therapy simply by increasing the number of dishes or flasks is not practical or economical. Here, we describe successful scaled‐up production of ESCs on microcarriers in a stirred culture system in a serum‐free medium. Cells expanded on CultiSpher S, Cytodex 3, and Collagen microcarriers showed superior cell‐fold expansions of 439, 193, and 68, respectively, without excessive agglomeration, compared with 27 in static culture. In addition, the ESCs maintained their pluripotency after long‐term culture (28 days) in serum‐free medium. This is the first time mESCs have been cultured on microcarriers without prior exposure to serum and/or fibroblasts, while also eliminating the excessive agglomeration plaguing earlier studies. These protocols provide an economical, practical, serum‐free means for expanding ESCs in a stirred suspension bioprocess. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Protein hydrolysis by immobilized and stabilized trypsin
Authors: Marques Daniela , Pessela Benavides C. , Betancor Lorena , Monti Rubens , Carrascosa Alfonso V. , Rocha‐Martin Javier , Guisán Jose M. , Fernandez‐Lorente Gloria
Published: March 2011

The preparation of novel immobilized and stabilized derivatives of trypsin is reported here. The new derivatives preserved 80% of the initial catalytic activity toward synthetic substrates [benzoyl‐arginine p‐nitroanilide (BAPNA)] and were 50,000‐fold more thermally stable than the diluted soluble enzyme in the absence of autolysis. Trypsin was immobilized on highly activated glyoxyl‐Sepharose following a two‐step immobilization strategy: (a) first, a multipoint covalent immobilization at pH 8.5 that only involves low pKa amino groups (e.g., those derived from the activation of trypsin from trypsinogen) is performed and (b) next, an additional alkaline incubation at pH 10 is performed to favor an intense, additional multipoint immobilization between the high concentration of proximate aldehyde groups on the support surface and the high pKa amino groups at the enzyme surface region that participated in the first immobilization step. Interestingly, the new, highly stable trypsin derivatives were also much more active in the proteolysis of high molecular weight proteins when compared with a nonstabilized derivative prepared on CNBr‐activated Sepharose. In fact, all the proteins contained a cheese whey extract had been completely proteolyzed after 6 h at pH 9 and 50°C, as determined by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). Under these experimental conditions, the immobilized biocatalysts preserve more than 90% of their initial activity after 20 days. Analysis of the three‐dimensional (3D) structure of the best immobilized trypsin derivative showed a surface region containing two amino terminal groups and five lysine (Lys) residues that may be responsible for this novel and interesting immobilization and stabilization. Moreover, this region is relatively far from the active site of the enzyme, which could explain the good results obtained for the hydrolysis of high‐molecular weight proteins. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Immobilization of active human carboxylesterase 1 in biomimetic silica nanoparticles
Authors: Edwards Jonathan S. , Kumbhar Amar , Roberts Adam , Hemmert Andrew C. , Edwards Carol C. , Potter Philip M. , Redinbo Matthew R.
Published: March 2011

The encapsulation of proteins in biomimetic silica has recently been shown to successfully maintain enzymes in their active state. Organophosphate (OP) compounds are used as pesticides as well as potent chemical warfare nerve agents. Because these toxicants are life threatening, we sought to generate biomimetic silicas capable of responding to OPs. Here, we present the silica encapsulation of human drug metabolism enzyme carboxylesterase 1 (hCE1) in the presence of a range of catalysts. hCE1 was successfully encapsulated into silica particles when lysozyme or the peptide R5 were used as catalysts; in contrast, polyethyleneimine, a catalyst used to encapuslate other enzymes, did not facilitate hCE1 entrapment. hCE1 silica particles in a column chromatography format respond to the presence of the OP pesticides paraoxon and dimethyl‐p‐nitrophenyl phosphate in solution. These results may lead to novel approaches to detect OP pesticides or other weaponized agents that bind hCE1. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Effect of sodium nitroprusside on growth and terpenoid indole alkaloid production in Catharanthus roseus hairy root cultures
Authors: Li Mai , Peebles Christie A. M. , Shanks Jacqueline V. , San Ka‐Yiu
Published: March 2011

Nitric oxide (NO) is known as a signaling molecule involved in elicitor‐induced defense responses of plants. Sodium nitroprusside (SNP), a donor of NO, stimulates catharanthine formation in Catharanthus roseus cells.1 Two important terpenoid indole alkaloids produced in small quantities within C. roseus are vinblastine and vincristine which are being used clinically as anticancer drugs. We are interested in engineering C. roseus hairy roots to increase the production of the TIAs. The present work investigates the effects of treating different concentrations of SNP to the hairy root cultures from line LBE‐6‐1. The alkaloid concentrations were analyzed 9, 14, 17, 20, 23, 26, and 30 days after treatment of SNP on day 0. We also studied the transient effects of SNP treatment during the exponential phase in C. roseus hairy roots. Analysis of the results showed that treatment of 0.1‐mM SNP did not affect the growth of hairy roots, whereas 1‐mM SNP suppressed the growth significantly, and 10‐mM SNP almost completely inhibited the growth of hairy roots. 0.1‐mM SNP treatment on day 0 caused a significant increase in the concentration of serpentine, catharanthine, ajmalicine, lochnericine and tabersonine production. SNP treatment on day 12 stimulated the formation of serpentine, catharanthine, ajmalicine, hörhammericine, lochnericine and tabersonine by day 21. After the initial stimulation, serpentine, horhammericine and lochnericine concentrations returned to the basal level by day 28. Treatment of 0.1‐mM SNP on day 0 caused significant decrease in the mRNA levels for TDC, ASA, STR, ORCA3, ZCT1, and Crgbf1 on day 23. Treating 0.1‐mM SNP on day 12 caused decreases in the expression levels of STR, ORCA3, ZCT1, and Crgbf1 on day 21 and day 28. Compared with day 28, the mRNA transcript of ZCT1 on day 21 is about twofold higher. Expression levels of G10H increased significantly. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Recent firsts in cadaveric impact biomechanics research
Authors: King Albert I. , Yang King H. , Hardy Warren N.
Published: March 2011

High‐speed biplane x‐ray and neutral density targets were used to examine brain displacement and deformation, as well as aortic motion and deformation within the mediastinum, during impact. Thirty‐five impacts using eight human cadaver head and neck specimens and eight impacts of the intact cadaver thorax are summarized. During impact, local brain tissue tends to keep its position and shape with respect to the inertial frame, resulting in relative motion between the brain and skull and deformation of the brain. The local brain motions tend to follow looping patterns. Similar patterns are observed for impact in different planes, with some degree of posterior–anterior and right–left symmetry. Clinically relevant damage to the aorta was observed in seven of the thorax tests. The presence of atherosclerosis was demonstrated to promote tearing. The isthmus of the aorta moved dorsocranially during frontal impact and submarining loading modes. The aortic isthmus moved medially and anteriorly during impact to the left side. Clin. Anat. 24:294–308, 2011. © 2011 Wiley‐Liss, Inc.
Human surrogates for injury biomechanics research
Authors: Crandall J.R. , Bose D. , Forman J. , Untaroiu C.D. , Arregui‐Dalmases C. , Shaw C.G. , Kerrigan J.R.
Published: March 2011

This article reviews the attributes of the human surrogates most commonly used in injury biomechanics research. In particular, the merits of human cadavers, human volunteers, animals, dummies, and computational models are assessed relative to their ability to characterize the living human response and injury in an impact environment. Although data obtained from these surrogates have enabled biomechanical engineers and designers to develop effective injury countermeasures for occupants and pedestrians involved in crashes, the magnitude of the traffic safety problem necessitates expanded efforts in research and development. This article makes the case that while there are limitations and challenges associated with any particular surrogate, each provides a critical and necessary component in the continued quest to reduce crash‐related injuries and fatalities. Clin. Anat. 24:362–371, 2011. © 2011 Wiley‐Liss, Inc.
Cadaver use at the University of Tennessee's Anthropological Research Facility
Authors: Shirley Natalie R. , Wilson Rebecca J. , Jantz Lee Meadows
Published: March 2011

The Anthropological Research Facility allows actualistic studies evaluating human decomposition to be conducted in a controlled, scientific setting. These studies have had significant ramifications for forensic investigations. Donated cadavers are used to study the precise nature and timing of decomposition events. More than 1,000 bodies have been donated, and more than 2,000 individuals are registered for donation on their death. Initial studies using cadavers focused on gross morphological changes of human decomposition, while more recent research has delved into biochemical analyses. This research has contributed to the accuracy of time since death estimations, which may be critical in criminal investigations. Furthermore, the donated cadavers contribute to the unprecedented diversity of the William M. Bass Donated Skeletal Collection, which allows for a wide range of skeletal‐based research. The continuous supply of human cadavers is essential for these research endeavors, and the Forensic Anthropology Center strives to ensure that donor wishes are fulfilled and to assure donors that their invaluable gift will serve the scientific community for years to come. Clin. Anat. 24:372–380, 2011. © 2011 Wiley‐Liss, Inc.
The relationship between lower neck shear force and facet joint kinematics during automotive rear impacts
Authors: Stemper Brian D. , Yoganandan Narayan , Pintar Frank A. , Maiman Dennis J.
Published: March 2011

A primary goal of biomechanical safety research is the definition of localized injury thresholds in terms of quantities that are repeatable and easily measureable during experimentation. Recent biomechanical experimentation using human cadavers has highlighted the role of lower cervical facet joints in the injury mechanism resulting from low‐speed automotive rear impacts. The present study was conducted to correlate lower neck forces and moments with facet joint motions during simulated rear impacts in an effort to define facet joint injury tolerance thresholds that can be used to assess automobile safety. Four male and four female intact head–neck complexes were obtained from cadaveric specimens and subjected to simulated automotive rear impacts using a pendulum‐minisled device. Cervical spine segmental angulations and localized facet joint kinematics were correlated to shear and axial forces, and bending moments at the cervico‐thoracic junction using linear regression. R2 coefficients indicated that spinal kinematics correlated well with lower neck shear force and bending moment. Correlation slope was steeper in female specimens, indicating greater facet joint motions for a given loading magnitude. This study demonstrated that lower neck loads can be used to predict lower cervical facet joint kinematics during automotive rear impacts. Higher correlation slope in female specimens corresponds to higher injury susceptibility in that population. Although lower neck shear force and bending moment demonstrated adequate correlation with lower cervical facet joint motions, shear force is likely the better predictor due to similarity in the timing of peak magnitudes with regard to maximum facet joint motions. Clin. Anat. 24:319–326, 2011. © 2011 Wiley‐Liss, Inc.
Genome‐wide analysis of gene expression in dendritic cells from rat regenerating liver after partial hepatectomy
Authors: Xu Cunshuan , Chen Xiaoguang , Chang Cuifang , Wang Gaiping , Wang Wenbo , Zhang Lianxing , Zhu Qiushi , Wang Lei
Published: March 2011

Dendritic cells (DCs) play a pivotal role in orchestrating immune response occurring in liver regeneration (LR). However, there are few details about relationship between DCs and LR at the molecular level. In this study, we firstly obtained high‐purity DCs by the combination of Percoll density gradient centrifugation and immunomagentic bead sorting, then measured genome‐wide gene expression in DCs from rat regenerating liver after partial hepatectomy (PH) using rat genome 230 2·0 microarray composed of 25 020 genes, and verified the reliability of microarray data with RT‐PCR method. Among 25 020 genes present on the array, 1621 known genes and 1307 unknown genes, totally 2928 genes, were identified to be LR‐related. H‐clustering analysis showed that 2928 genes were grouped into three expression patterns: up‐regulation, down‐regulation and complex changes in expression. And 1621 known genes were functionally grouped into at least 23 biological categories. When expression patterns were combined with gene functions, as a whole, the genes involved in immune/defence response, inflammatory response and secretion of active substance in DCs were highly enriched in down‐regulated pattern. DCs exhibited the reduced immune/defence and inflammatory response, and the suppressed secretion capacity of active substances after PH. A further analysis of genes expressed in the phase‐dependent manner during LR suggested the rapid induction of genes encoding some transcription factors and cytokines in DCs at immediate‐early phase, the unobvious enhancement of metabolic process, immunity and inflammation at proliferation phase, while the impairment of detoxification, immunity and inflammation at terminal phase. Copyright © 2011 John Wiley & Sons, Ltd.
Kinetic Model of Gas‐Liquid‐Liquid Reactive Extraction for Production of Hydrogen Peroxide
Authors: Lu S. , Wang L. , Wang Y. , Mi Z.
Published: March 2011

The kinetic aspects of the gas‐liquid‐liquid reactive extraction process for the production of hydrogen peroxide were investigated in a batch reactor. It was observed that the gas‐liquid reaction rate is strongly affected by mass transfer of oxygen across the liquid film and the reaction can be simplified to pseudo‐first order. The extraction rate is governed by both reaction and liquid‐liquid mass transfer, and is slightly lower than the reaction rate. In addition, a kinetic model of the reactive extraction process for the production of hydrogen peroxide was developed. Kinetic parameters under different conditions were determined by experiments. The data calculated from the kinetic model match experimental data well under different conditions for hydrogen peroxide production in gas‐liquid‐liquid reactive extraction.
Optimization of Methanol Yield from a Lurgi Reactor
Authors: Chen L. , Jiang Q. , Song Z. , Posarac D.
Published: March 2011

Methanol is an important chemical with the potential to become an alternative fuel. An optimization study was performed for a Lurgi methanol synthesis reactor using the commercial process simulator Aspen Plus. The optimization routine is coupled with a steady‐state model of the methanol synthesis reactor. Syngas inlet temperature, steam drum pressure, and cooling water volumetric flow rate were optimized so that methanol production in the reactor outlet was maximized. The methanol yield increased by 7.04 %.
Tandem Insertion of Halocarbenoids and Lithium Acetylides into Zirconacycles: A Novel Rearrangement to Zirconium Alkenylidenates by β‐Addition to an Alkynyl Zirconocene
Authors: Stec Jozef , Thomas Emma , Dixon Sally , Whitby Richard J.
Published: March 2011

Tandem insertion of 1,1‐dihalo‐1‐lithio species (halocarbenoids) and lithium alkynides into zirconacyclopentenes and zirconcyclopentanes affords carbocyclic products in high yields via an unusual rearrangement that probably involves addition of an organolithium species to the β‐position of a zirconium–alkyne complex to give an alkenylidene–zirconate species. A wide variety of cyclopentanoid organic structures are rapidly assembled in good yield using this multicomponent coupling. The main side reaction, which becomes exclusive in some cases, is β‐hydride elimination of an intermediate cyclopentyl‐ or cyclopentenyl zirconocene.