bluuebunny/crossref_metadata_2025 huggingface dataset:
The experiences of AIDS orphans living in a township
Authors: Van Rooyen Dalena , Frood Sharon , Ricks Esmeralda
Published: February 2012

An overwhelming challenge to health-care professionals today, is the rendering of care services to AIDS orphans. This article is based on a study that explored and described the lived experiences of AIDS orphans in a township in order to understand their ‘life world’ as AIDS orphans. A further purpose was to provide information to primary health-care nurses (PHCNs), related professionals and partners involved in the care of these children, so that they could plan a care response to meet the orphans’ unique needs. A qualitative research design that used an explorative, descriptive, contextual and phenomenological strategy of inquiry was employed. Data were collected by means of in-depth interviews from a purposively selected sample, and were analysed according to the steps of qualitative data analysis proposed by Tesch (Creswell 1994). Guba’s model was used to ensure the trustworthiness of the qualitative data. Two main themes and their sub-themes were identified. The first theme was that children experience devastating changes in their life circumstances when they become AIDS orphans. The second theme highlighted how the participants rediscovered hope to persevere. Recommendations directed at nursing practice, education and research, were made based upon the findings.Opsomming‘n Uitdaging wat professionele gesondheidswerkers huidiglik oorweldig, is dienslewering aan VIGS weeskinders. Die doel van die studie was om die geleefde ervaring van kinders wat in dorpsgebiede woon en VIGS weeskinders geword het, te verken en te beskryf ten einde hul leefwêreld te verstaan. Hierdie inligting kan deur Primêre Gesondheidsorg Verpleegkundiges (PVGs), verwante beroepslui en vennote betrokke by die versorging van hierdie kinders, gebruik word as basis om versorging te beplan wat in die kinders se unieke behoeftes sal voorsien. ‘n Kwalitatiewe navorsingsontwerp met verkennende, beskrywende, kontekstuele en fenomologiese strategieë van ondersoek, is gebruik. Data is versamel deur middel van in-diepte onderhoude met ‘n doelbewus geselekteerde steekproef. Data is geanaliseer ooreenkomstig die stappe van kwalitatiewe data analise volgens Tesch (in Creswell 1994). Guba se model was gebruik om die betroubaarheid van data te bepaal. Twee hooftemas en hul subtemas is geïdentifiseer. Die eerste tema was dat kinders dramatiese veranderinge in hulle lewensomstandighede ervaar wanneer hulle VIGS weeskinders word. Die tweede tema wat na vore gekom het, was hoe die deelnemers die hoop om voort te gaan met die lewe, herontdek het. Aanbevelings, gebaseer op die bevindinge, is gemaak wat verpleegpraktyk, onderrig en navorsing sal rig.
Evaluation of the smoke-injection height from wild-land fires using remote-sensing data
Authors: Sofiev M. , Ermakova T. , Vankevich R.
Published: February 2012

Abstract. A new methodology for the estimation of smoke-injection height from wild-land fires is proposed and evaluated. It is demonstrated that the approaches developed for estimating the plume rise from stacks, such as the formulas of G. Briggs, can be formally written in terms characterising the wild-land fires: fire energy, size and temperature. However, these semi-empirical methods still perform quite poorly because the physical processes controlling the uplift of the wildfire plumes differ from those controlling the plume rise from stacks. The proposed new methodology considers wildfire plumes in a way similar to Convective Available Potential Energy (CAPE) computations. The new formulations are applied to a dataset collected within the MISR Plume Height Project for about 2000 fire plumes in North America and Siberia. The estimates of the new method are compared with remote-sensing observations of the plume top by the MISR instrument, with two versions of the Briggs' plume-rise formulas, with the 1-D plume-rise model BUOYANT, and with the prescribed plume-top position (the approach widely used in dispersion modelling). The new method has performed significantly better than all these approaches. For two-thirds of the cases, its predictions deviated from the MISR observations by less than 500 m, which is the uncertainty of the observations themselves. It is shown that the fraction of "good" predictions is much higher (>80%) for the plumes reaching the free troposphere.
Modelling future changes in surface ozone: a parameterized approach
Authors: Wild O. , Fiore A. M. , Shindell D. T. , Doherty R. M. , Collins W. J. , Dentener F. J. , Schultz M. G. , Gong S. , MacKenzie I. A. , Zeng G. , Hess P. , Duncan B. N. , Bergmann D. J. , Szopa S. , Jonson J. E. , Keating T. J. , Zuber A.
Published: February 2012

Abstract. This study describes a simple parameterization to estimate regionally averaged changes in surface ozone due to past or future changes in anthropogenic precursor emissions based on results from 14 global chemistry transport models. The method successfully reproduces the results of full simulations with these models. For a given emission scenario it provides the ensemble mean surface ozone change, a regional source attribution for each change, and an estimate of the associated uncertainty as represented by the variation between models. Using the Representative Concentration Pathway (RCP) emission scenarios as an example, we show how regional surface ozone is likely to respond to emission changes by 2050 and how changes in precursor emissions and atmospheric methane contribute to this. Surface ozone changes are substantially smaller than expected with the SRES A1B, A2 and B2 scenarios, with annual global mean reductions of as much as 2 ppb by 2050 vs. increases of 4–6 ppb under SRES, and this reflects the assumptions of more stringent precursor emission controls under the RCP scenarios. We find an average difference of around 5 ppb between the outlying RCP 2.6 and RCP 8.5 scenarios, about 75% of which can be attributed to differences in methane abundance. The study reveals the increasing importance of limiting atmospheric methane growth as emissions of other precursors are controlled, but highlights differences in modelled ozone responses to methane changes of as much as a factor of two, indicating that this remains a major uncertainty in current models.
A laboratory investigation into the aggregation efficiency of small ice crystals
Authors: Connolly P. J. , Emersic C. , Field P. R.
Published: February 2012

Abstract. The aggregation of ice crystals and its temperature dependence is studied in the laboratory using a large ice cloud chamber. This process is important to the evolution of ice clouds in earth's atmosphere, yet there have been relatively few laboratory studies quantifying this parameter and its dependence on temperature. A detailed microphysical model is used to interpret the results from the experiments and derive best estimates for the aggregation efficiency as well as error bars. Our best estimates for the aggregation efficiency, at temperatures other than −15 °C, (in the interval −30≤T≤5 °C) are mostly in agreement with previous findings, which were derived using a very different approach to that described here. While the errors associated with such experiments are reasonably large, statistically, at temperatures other than −15, we are able to rule out aggregation efficiencies larger than 0.5 at the 75th percentile and rule out non-zero values at −15 °C, whereas at −15 °C we can rule out values higher than 0.85 and values lower than 0.35. The values of the aggregation efficiency shown here may be used in model studies of aggregation, but care must be taken that they only apply for the initial stages of aggregate growth, with humidities at or close to water saturation, and for particles up to a maximum size of ~500 μm. They may therefore find useful application for modelling supercooled mid-level layer clouds that contain ice crystals, which are known to be important radiatively.
Aerosol-precipitation interactions in the southern Appalachian Mountains
Authors: Kelly G. M. , Taubman B. F. , Perry L. B. , Sherman J. P. , Soulé P. T. , Sheridan P. J.
Published: February 2012

Abstract. There are many uncertainties associated with aerosol-precipitation interactions, particularly in mountain regions where a variety of processes at different spatial scales influence precipitation patterns. Aerosol-precipitation linkages were examined in the southern Appalachian Mountains, guided by the following research questions: (1) how do aerosol properties observed during precipitation events vary by season (e.g., summer vs. winter) and synoptic event type (e.g., frontal vs. non-frontal); and (2) what influence does air mass source region have on aerosol properties? Precipitation events were identified based on regional precipitation data and classified using a synoptic classification scheme developed for this study. Hourly aerosol data were collected at the Appalachian Atmospheric Interdisciplinary Research (AppalAIR) facility at Appalachian State University in Boone, NC (1110 m a.s.l., 36.215°, −81.680°). Backward air trajectories provided information on upstream atmospheric characteristics and source regions. During the warm season (June to September), greater aerosol loading dominated by larger particles was observed, while cool season (November to April) precipitation events exhibited overall lower aerosol loading with an apparent influence from biomass burning particles. Aerosol-induced precipitation enhancement may have been detected in each season, particularly during warm season non-frontal precipitation.
P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model
Authors: Draebing D. , Krautblatter M.
Published: February 2012

Abstract. P-wave refraction seismics is a key method in permafrost research but its applicability to low-porosity rocks, that constitute alpine rock walls, has been denied in prior studies. These explain p-wave velocity changes in freezing rocks exclusively due to changing velocities of pore infill, i.e. water, air and ice. In existing models, no velocity increase is expected for low-porosity bedrock. We postulate, that mixing laws apply for high-porosity rocks, but freezing in confined space in low-porosity bedrock also alters physical rock matrix properties. In the laboratory, we measured p-wave velocities of 22 decimeter-large low-porosity (<6 %) metamorphic, magmatic and sedimentary permafrost rock samples with a natural texture (>100 micro-fissures) from 25 °C to –15 °C in 0.3 °C increments close to the freezing point. P-wave velocity increases by 7–78 % when freezing parallel to cleavage/bedding and matrix velocity increases from 5–59 % coincident to an anisotropy decrease in most samples. The expansion of rigid bedrock upon freezing is restricted and ice pressure will increase matrix velocity and decrease anisotropy while changing velocities of the pore infill are insignificant. Here, we present a modified Timur's 2-phase equation implementing changes in matrix velocity dependent on lithology and demonstrate the physical basis for refraction seismics in low-porosity bedrock.
The Neoteny Barrier: Seeking Respect for the Non-Cute
Authors: Estren Mark J.
Published: February 2012

A foundational human attraction to mammalian neoteny may be crucial for preservation of our own species, but it can be counterproductive in relationships between humans and other animals. The deeply rooted human psychological attraction to and preference for anthropomorphically viewed neotenic characteristics explains why some animals, whether endangered or not, receive far more public attention and scientific study than others. An understanding of the neoteny barrier makes it possible to find ways around it: The barrier may not be possible to break, but it can be modified by scientific awareness of its existence and an alteration of public perception of value to include animals who would not, in neotenic terms, be considered cute.
Opening the Door: Non-Veterinarians and the Practice of Complementary and Alternative Veterinary Medicine
Authors: Schommer Megan
Published: February 2012

Growing interest in complementary and alternative veterinary medicine (CAVM) has sparked a debate among veterinarians, who claim such therapeutic modalities fall under the purview of veterinary medicine, and non-veterinarians, who argue that several modalities do not require the rigorous training of a veterinarian to be performed safely. The veterinary profession must proactively redefine its definition of the practice of veterinary medicine in the face of increasing challenges to state practice acts. By looking to human medicine as a model for how to balance conventional and alternative modalities, the profession can develop a system that provides animal caregivers access to CAVM while still safeguarding animal health.
Laying the Foundations for an International Animal Protection Regime
Authors: Otter Caley , O’Sullivan Siobhan , Ross Sandy
Published: February 2012

In this article we consider what form a future supranational animal protection regime might take. We conclude that no such regime exists at present, although one is likely to develop over the next couple of decades, with two viable options already on the horizon. One model would see the role of the World Organisation for Animal Health (OIE) extended, whereas the other would occur within the context of the United Nations (UN). The former would suit agricultural interests, whereas the latter would probably appeal to so-called new welfarists. However, neither is likely to satisfy animal rights advocates because both regimes assume animals can be legitimately traded and utilized as means to human ends.
Some Ancient and Modern Views on the Expression of Shame in Animals
Authors: Newmyer Stephen T.
Published: February 2012

Greco-Roman philosophers and historians frequently attempted to define the human being vis-á-vis other animals by isolating capacities, intellectual, physical, and emotional, judged unique to humans. The Stoic claim that only humans have a sense of shame because only humans are rational and therefore capable of emotions, which entail reasoning, was contradicted by other philosophers and naturalists who argued that some animal behaviors were analogous to behavior in humans that indicate shame. Ancient debates on both sides of the issue of animal emotions are paralleled in current philosophy and cognitive ethology employing anecdotal and anthropomorphizing arguments that mirror classical examples.
Toward a Theory of Justice for Animals
Authors: Garner Robert
Published: February 2012

This highly recommended book explores the animal ethics debate from the perspective of Western political thought, offering the reader not only a survey but also the framework for an original interest-based theory of animal rights. Cochrane’s operating definition of justice is of limited use, and the author is perhaps too uncritical of the utility of employing justice as a means to protect the interests of animals. It is suggested, too, that an account of the political theory of animal rights can invoke profitably the debate between exponents of ideal and non-ideal theories of justice.
Interplay between Bimolecular Recombination and Carrier Transport Distances in Bulk Heterojunction Organic Solar Cells
Authors: Tumbleston John R. , Liu Yingchi , Samulski Edward T. , Lopez Rene
Published: February 2012

In this work, it is demonstrated that bimolecular recombination depends on the distance that free carriers are required to travel in transit to the electrodes in bulk heterojunction organic solar cells. By employing semi‐transparent devices, the carrier transport distance can be controlled via the local light absorption profile with an appropriate choice of the illumination side and incident wavelength. Using a series of light intensity‐dependent measurements, bimolecular recombination is shown to depend on the distance electrons or holes are required to transit the active layer. This effect is demonstrated for three different bulk heterojunction blends, where the restrictive carrier that causes the onset of recombination is identified. The mobility‐lifetime products of the limiting carriers are also estimated using a simple model for carrier extraction, where similar values are obtained regardless of the absorption profile. Implications for 1‐sun performance are also discussed, which provide guidelines for fabricating devices with thicker active layers capable of maximizing light absorption without succumbing to recombination losses.
On separation efficiency
Authors: Cussler E. L. , Dutta Binay K.
Published: February 2012

Rising energy costs have renewed interest in energy efficient separations. Such efficiencies can be defined as the free energy of unmixing divided by the work done on and the heat added to the process. The greatest efficiencies occur when the energy cost far exceeds any capital cost. In this limit, rate processes are not important, and efficiency is governed by thermodynamics. Efficiencies for gas absorption and stripping are then typically around 50%. The efficiencies of liquid–liquid extractions are lower, especially when one solute is wanted at higher concentration. The efficiencies of membrane separations are higher, but these require high pressure, normally obtained mechanically. As a result, membrane efficiencies should be reduced by any Carnot efficiency of generating the mechanical energy. These results, which are consistent with earlier estimates for distillation, have implications for carbon dioxide capture as a route to mitigating global warming. © 2012 American Institute of Chemical Engineers AIChE J, 2012
Preserving workers' dignity in workers' compensation systems: An international perspective
Authors: Lippel Katherine
Published: February 2012

Background

Workers' compensation systems are among the most generous disability insurance systems in North America, although they are also known to be potentially adversarial and may have iatrogenic effects on claimants. This article examines issues to be considered to ensure fair compensation provided in a way that respects the dignity of workers.

Methods

An overview of the literature on characteristics and effects of workers' compensation systems is followed by an analysis based on classic legal methods, including those of comparative law, complemented with interview data to examine three models of disability compensation.

Results

The first part of the article identifies cross cutting issues to be considered in the examination of the equity of compensation systems and the protection of the dignity of claimants. These include three underpinnings of workers' compensation: the links between a “no‐fault” system and the adversarial process, the appropriate use of medical and scientific evidence in the determination of compensability and the application of appropriate measures for promoting return to work. The second part looks at accident compensation in New Zealand, where compensation is available regardless of the cause of the accident, and disability insurance in the Netherlands, where compensation is available regardless of the cause of the disability. It then describes a composite of characteristics favorable to equity drawn from the thirteen workers' compensation systems in Canada.

Conclusion

Systems that succeed in reducing opportunities for adversarial interactions and that provide substantive protection could better promote the dignity of claimants. Am. J. Ind. Med. 55:519–536, 2012. © 2012 Wiley Periodicals, Inc.
Karyotype/phenotype correlation in partial trisomies of the long arm of chromosome 16: Case report and review of literature
Authors: Laus Ana C. , Baratela Wagner A.R. , Laureano Lucimar A.F. , Santos Silvio A. , Huber Jair , Ramos Ester S. , Rebelo Camila C. , Squire Jeremy A. , Martelli Lucia
Published: February 2012

Trisomy 16q is a clinically recognizable entity presenting with a wide spectrum of abnormalities. Only five infants with a diagnosis of partial trisomy 16q13 → qter have been previously reported, and all died during the first year of life. We report the clinical and molecular cytogenetic findings in a patient with trisomy 16q13 → qter due to the presence of a supernumerary marker chromosome (SMC). The child presented with microcephaly, ambiguous genitalia, cardiac malformations and dysmorphic features. Cytogenetic investigation using GTG‐banding, spectral karyotyping (SKY) and fluorescence in situ hybridization analyses revealed an SMC of maternal origin with karyotype der(15)t(15;16)(q13;q13). Specific genotype–phenotype correlations among different segments of the 16q region cannot yet be defined. We suggest that the involvement of the entire region spanning from 16q11 to 16q22 is necessary for the characteristic phenotype of the trisomy 16q. © 2012 Wiley Periodicals, Inc.
Hydrocephalus with Hirschsprung disease: Severe end of X‐linked hydrocephalus spectrum
Authors: Takenouchi Toshiki , Nakazawa Mie , Kanemura Yonehiro , Shimozato Sachiko , Yamasaki Mami , Takahashi Takao , Kosaki Kenjiro
Published: February 2012

L1CAM molecule is a cell adhesion molecule in nervous and enteric systems and is responsible for X‐linked hydrocephalus (XLH) spectrum, which is a rare condition with severe congenital hydrocephalus, dysgenesis of the corpus callosum, intellectual disability, spasticity, and adducted thumbs. Several cases of XLH accompanied by Hirschsprung disease (HSCR) have been reported in the literature, but whether HSCR results from a gain‐of‐function mutation in cases with XLH, i.e., a neomorphic mutation, or the severe end of the L1CAM mutation spectrum remains unclear. The present patient was a Japanese boy with severe congenital hydrocephalus with aqueductal stenosis as well as hypoplasia of the corpus callosum. HSCR had been confirmed by a biopsy. A mutation analysis of the L1CAM gene showed a C61T mutation in exon 1, resulting in a truncating nonsense mutation at amino acid position 21 and producing an extremely short protein that was unlikely to interact with other proteins. These findings suggest that XLH‐HSCR represents the severe end of the XLH spectrum, rather than a neomorphic mutation. A thorough abdominal investigation to rule out HSCR should be considered in patients with XLH accompanied by severe constipation. © 2012 Wiley Periodicals, Inc.
Association of Catechol‐O‐methyltransferase gene polymorphisms with schizophrenia and negative symptoms in a Chinese population
Authors: Li Wen Jun , Kou Chang Gui , Yu Yaqin , Sun Shilong , Zhang Xuan , Kosten Thomas R. , Zhang Xiang Yang
Published: February 2012

The gene encoding Catechol‐O‐methyltransferase (COMT), a dopamine catabolic enzyme, has been associated inconsistently with schizophrenia in spite of consistent evidence for dopaminergic dysfunction in the prefrontal cortex (PFC) of schizophrenia. Since one contribution to this inconsistency might be genetic heterogeneity, this study investigated whether the COMT gene was associated with the development and symptoms of schizophrenia in relatively genetically homogeneous Chinese schizophrenic patients. We analyzed two polymorphisms (rs740603 and rs4818) of the COMT gene in a case‐control study of 604 Han Chinese (284 patients and 320 controls). The patients' psychopathology was assessed using the Positive and Negative Syndrome Scale (PANSS). We found no significant differences in the rs740603 and rs4818 genotype and allele distributions between the patient and control groups. Quantitative trait analysis by the UNPHASED program showed that the rs740603 and rs740603(G)‐rs4818(G) haplotypes were associated with negative symptoms in the schizophrenic patients, particularly among female patients. Thus, the COMT gene polymorphisms may not contribute to the susceptibility to schizophrenia, but may contribute to the negative symptoms of schizophrenia among Han Chinese. © 2012 Wiley Periodicals, Inc.
Synthesis of bifunctional cellulosic adsorbent by radiation induced graft polymerization of glycidyl methacrylate‐co‐methacrylic acids
Authors: Sokker H. H. , Gad Y. H. , Ismail S. A.
Published: February 2012

A bifunctional cotton fabric waste bearing N+ (CH2CH3)3 and COOH groups was prepared by radiation induced graft polymerization of glycidyl methacrylate and methacrylic acid using gamma irradiation and subsequent chemical modification of the grafted cotton fabric with triethylamine. Factors affecting the grafting of cotton fabric such as radiation dose and comonomer composition were investigated. The adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscope. Functional groups were tested for its potential application in the removal of cobalt (Co2+) and nitrate (NO) from aqueous solutions. Batch experiments were performed to evaluate the adsorption efficiency of the modified grafted cellulose (MGC) towards the cation and the anion. The adsorption capacity for Co2+ at pH 3 and pH 5 was 36.0 and 38.5 mg/g, respectively, whereas that of nitrate was 11 mg/g at pH 4.5. The adsorption process of Co2+ and nitrate obeys both Freundlich and Langmuir isotherm models and followed Pseudosecond order kinetics. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Polymer–copper‐modified MWNTs by radiation‐induced graft polymerization and their efficient adsorption of odorous gases
Authors: Kim Kyo‐Il , Oh Sang‐Hyeb , Kwen Hai‐Doo , Choi Seong‐Ho
Published: February 2012

Polymer–copper‐modified multi‐walled carbon nanotubes (MWNTs) were prepared by radiation‐induced graft polymerization of epoxy‐containing glycidyl methacrylate and subsequent amination and Cu complexing. Two amines, triethyldiamine and imidazol, were used as polymeric ligand compounds. The Cu‐modified MWNTs were confirmed by high‐resolution transmittance electron microscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy, and thermal gravimetric analysis. The dynamic adsorption of odor gases, such as CH3SH and H2S, on the Cu‐modified MWNTs and amine‐modified MWNTs was also evaluated. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synergistic antimicrobial effects of polyaniline combined with silver nanoparticles
Authors: Jia Qingming , Shan Shaoyun , Jiang Lihong , Wang Yaming , Li Dan
Published: February 2012

Silver/polyaniline nanocomposites (Ag NPs/PANI) containing PANI nanofiber and Ag nanoparticles were synthesized by one‐step approach without using any extra reducing agent or surfactant and applied to new antimicrobial agents. Morphologies and crystallinity of the nanocomposites were characterized with SEM and XRD. The results showed that the average diameter of the PANI nanofibers is around 50–150 nm, and the average particle size of Ag NPs is around 100 nm. The crystallinity of PANI gets better with increasing silver nitride concentration. UV–vis absorption spectroscopy analysis indicated that the Ag NPs have some effect on the microstructure of PANI. The antimicrobial properties of Ag NPs/PANI against Gram‐negative Escherichia coli, Gram‐positive Staphylococcus aureus and fungous Yeast were evaluated using viable cell counts. The test results demonstrated that Ag NPs/PANI have enhanced antimicrobial efficacy compared to that of pure Ag NPs or pure PANI under the same test condition. The mechanism of the synergistic antimicrobial effect of Ag NPs with PANI was also proposed. In addition, thermal gravity analysis indicated that pure PANI and Ag NPs/PANI exhibit better thermal stability. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effects of talc on the mechanical and thermal properties of polylactide
Authors: Yu Fengmei , Liu Tao , Zhao Xiuli , Yu Xuejiang , Lu Ai , Wang Jianhua
Published: February 2012

Polylactide (PLA) composites with various talc content were prepared by melt extrusion. The thermal, dynamic mechanical, tensile and flexural properties, and fracture surface morphologies of neat PLA and PLA/talc composites were investigated and compared. The results showed that talc had significant nucleation effect and the cold crystallization temperature of PLA decreased with talc concentration. The thermal degradation and heat distortion temperature of PLA were slightly enhanced by compounding with talc. Talc showed significant reinforcing and toughening effects on PLA, the tensile strength, flexural strength and modulus increased with talc content ranging from 0 to 24.3 wt %. The results of tensile test showed that the elongation at break increased with talc content up to 18.1 wt % with obvious changes in fracture behavior, changing from brittle to ductile, when talc content increased to 24.3%, samples failed in a brittle manner with low elongation at break. The fracture surface morphologies showed that the talc layers were partially delaminated, aligned along the flow direction, and uniformly dispersed in the PLA matrix. The results obtained by SEM and FTIR confirmed that the interfacial adhesion between talc and PLA matrix was good. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Dynamic mechanical properties of curaua composites
Authors: Ornaghi Heitor Luiz , da Silva Humberto Sartori Pompeo , Zattera Ademir José , Amico Sandro Campos
Published: February 2012

In this study, we aimed to evaluate the characteristics of curaua composites using dynamic mechanical analysis. Curaua composites with distinct fiber volume fractions (11–38%) were studied, and their storage and loss moduli were found to increase with reinforcement content. On the other hand, the activation energy of the relaxation process in the glass‐transition region decreased with the curaua content; this conclusion was corroborated by the elastic chain concentration results. The Cole–Cole plots became flattened as the curaua content increased; this was indicative of a more homogeneous system, and the tan δ peak height and peak width at half‐height decreased. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effect of cobalt‐60 γ radiation on the physical and chemical properties of poly(ethylene terephthalate) polymer
Authors: Siddhartha  , Aarya Suveda , Dev Kapil , Shakir Mohd , Ahmed Bashir , Wahab M. A.
Published: February 2012

The structural, optical, and morphological properties of Co60 γ irradiation on poly(ethylene terephthalate) polymer samples were studied with X‐ray diffraction (XRD), ultraviolet–visible spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy. The diffraction pattern of virgin sample showed that the polymer was semicrystalline in nature. However, because of irradiation, the crystallinity decreased up to a dose level of 110 kGy and increased up to 300 kGy. The crystallite size, strain, and dislocation were calculated from the XRD data, and the crystallite size decreased from 291.07 to 346.90 Å. The absorption edge shifted from 315 to 330 nm, and the band gap of the samples decreased from 3.79 to 3.66 eV. The SEM micrographs showed radial bulging along with inhomogeneous liner exfoliation, and also, a rocky shape pattern with different sizes was observed. A significant change was found in the Raman spectra of the γ‐irradiated polymer at the highest dose. The results of the structural, optical, and morphological studies show recovery characteristics at the highest dose level of 300 kGy. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Properties of styrene butadiene rubber/recycled acrylonitrile‐butadiene rubber (SBR/NBRr) blends: Effect of the addition of trans‐polyoctylene rubber
Authors: Noriman N. Z. , Ismail H. , Rashid A. A.
Published: February 2012

This study investigated polymer blends based on different ratios of styrene butadiene rubber (SBR) and recycled acrylonitrile butadiene rubber (NBRr) with and without trans‐polyoctylene rubber (TOR) as a compatibilizer. Five compositions of SBR/NBRr/TOR were prepared; 95/5/5, 85/15/5, 75/25/5, 65/35/5, and 50/50/5. Rheological characteristics, tensile and physical properties, and the morphological behavior of compatibilized and uncompatibilized SBR/NBRr blends were determined. The rheological characteristics indicated that compatibilized SBR/NBRr blends had a shorter cure time (t90) than uncompatibilized SBR/NBRr blends. The compatibilized SBR/NBRr blends showed lower minimum torque (ML) when compared with as uncompatibilized SBR/NBRr blends, indicating that compatibilization improved the processability of the blends. However, the maximum torque (MH) of compatibilized SBR/NBRr blends was higher than that of uncompatibilized SBR/NBRr blends. The incorporation of TOR improved the tensile strength, tensile modulus (M100), hardness, and crosslinked density of compatibilized SBR/NBRr blends. However, the elongations at break (Eb) and resilience of compatibilized SBR/NBRr blends were lower as compared to uncompatibilized SBR/NBRr blends. Scanning electron microscopy of the tensile fractured surfaces demonstrated that the addition of TOR in SBR/NBRr blends improved the adhesion between NBRr and the SBR matrix, thus improving the compatibility of SBR/NBRr blends. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Production and characterization of hybrid BEH‐PPV/PEO conjugated polymer nanofibers by forcespinning™
Authors: Padron Simon , Patlan Richard , Gutierrez Jose , Santos Nestor , Eubanks Thomas , Lozano Karen
Published: February 2012

The fabrication of hybrid poly(2,5‐bis(2′‐ethyl‐hexyl)‐1,4‐phenylenevinylene) (BEH‐PPV) and polyethylene oxide (PEO) nanofibers is reported. Nanofibers were created using a novel production method that uses centrifugal rather than electrostatic force to produce nanofibers. The nanofiber production method exhibits high yield production of nanofibers enabling mass‐production capabilities. Thermo‐physical characterization and X‐ray diffraction of bulk PEO and BEH‐PPV was conducted, and the results are compared with the produced hybrid nanofibers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Functional terpolymers containing vinylphosphonic acid: The synthesis and characterization of poly(vinylphosphonic acid‐co‐styrene‐co‐maleic anhydride)
Authors: Kavlak Serap , Güner Ali , Rzayev Zakir M. O.
Published: February 2012

Novel functional temperature‐sensitive amphiphilic P‐containing polymers were synthesized by complex‐radical ternary polymerization of vinylphosphonic acid (VPA), styrene (S), and maleic anhydride (MA). Charge transfer complexes (CTCs), complex‐formation constants (Kc) between acceptor and donor monomer systems and the complexed monomer reactivity ratios were investigated by 1H‐NMR analysis. Contrary to theoretical predictions, the VPA…S complex is more active as compared to MA…S complex in the ternary system since VPA monomer can form the CTC both with S monomer and strong H‐bonded complex with MA monomer. The terpolymer compositions, characterizations, and structure–property relationships of a series of poly(VPA‐co‐S‐co‐MA)s were investigated by GPC, FTIR, Raman, 1H‐NMR, 13C‐NMR, DEPT‐135, 31P‐NMR, TGA‐DSC, DMA, XRD, viscometry, and titration. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effective aminolytic depolymerization of poly(ethylene terephthalate) waste and synthesis of bisoxazoline therefrom
Authors: Shah Rikhil V. , Shukla Sanjeev R.
Published: February 2012

Aminolytic depolymerization of postconsumer poly(ethylene terephthalate) (PET) bottle waste with 2‐amino‐2‐methyl‐1‐propanol and 1‐amino‐2‐propanol under atmospheric condition was investigated in the presence of catalysts zinc acetate or sodium acetate. The virtual products obtained in pure form were, respectively, bis(1‐hydroxy‐2‐methylpropan‐2‐yl)terephthalamide and bis(2‐hydroxypropyl)terephthalamide. The latter was taken for further studies because of its higher yield and subjected to cyclization using thionyl chloride under low‐temperature conditions to get 1,4‐bis(5‐methyl‐4,5‐dihydrooxazol‐2‐yl)benzene, which is used as chain extender in polyester and nylon compositions and as a crosslinking agent in powder paint compositions. The products obtained from depolymerization were characterized by TLC, melting point, IR spectroscopy, 1H‐NMR, 13C‐NMR, and DSC. We have shown that it is possible to synthesize new utility products by recycling of PET waste. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Investigation of the curing process of spray polyurea elastomer by FTIR, DSC, and DMA
Authors: Zhou Qing , Cao Li , Li Qing , Yao Yalin , Ouyang Zhaofei , Su Zhiqiang , Chen Xiaonong
Published: February 2012

The curing process of a typically formulated spray polyurea elastomer (SPUA) system has been thoroughly investigated with the help of a combined analysis of Fourier transform infrared spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis. The evolvement of the microstructure and mechanical responses of the SPUA system during the curing process have been described in detail. The experimental results indicated that the fast curing property of SPUA, which mainly based on the reaction between the primary amine groups and the isocyanate groups, led to the formation of the unstable hard segments in the interphase. After the tack‐free time, the residual isocyanate groups continued to react with the rest of the secondary amine groups of the chain extenders for several hours and caused the increase of the molecular weight of the hard segment in SPUA. Furthermore, during the curing process, the “disordered” hydrogen bond formed by one CO and one nearby NH (secondary amine) reconstructed to “ordered” bond, which contributed to the increase of the content of the hard segment and ultimately, improved the mechanical properties of the SPUA system greatly. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effects of electrostatic polarity and the types of electrical charging on electrospinning behavior
Authors: Wu Chang‐Mou , Chiou Hau‐Geng , Lin Siang‐Ling , Lin Jian‐Min
Published: February 2012

In this study, we examined the effect of applied electrostatic voltages and the types of electrical charging on jet movement, fiber productivity, fiber diameter and deposited configuration by two inverse polarity systems, termed as spinneret and collector charging systems. Jet movement parameters such as Taylor cone, straight jet length, whipping angle, and pitch of whipping loop are examined and compared. The results show that the electronegative collector charging system or the electropositive spinneret charging system is superior to their contrastive system in terms of smaller fiber diameter, compact fiber deposited configuration, and higher fiber productivity. Optimal applied voltage found was 25 kV for electronegative collector charging system and 30 kV for electropositive spinneret charging system and resulted in finest fiber diameter (209 nm for electronegative collector charging system and 247 nm for electropositive spinneret charging system). Polyvinyl acetate solution jet is easier to be ejected, stretched, and accelerated under electropositive charging. The spinning jet with electropositive charges can be achieved either in the spinneret charging system by using electropositive charger or in the collector charging system by using electronegative charger. This finding is an important guideline for the designing of electrospinning device. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Overview on the production of biodiesel from Jatropha curcas L. by using heterogenous catalysts
Authors: Yusuf Nik N.A.N. , Kamarudin Siti K. , Yaakob Zahira
Published: February 2012

Jatropha curcas oil (JCO) is considered a future feedstock for biodiesel production because it is easily grown in harsh environments and is a non‐edible crop that is not in demand as a food source. Three basic methods are used to produce biodiesel from oils/fats, namely the base‐catalyzed transesterification, acid‐catalyzed transesterification, and enzymatic catalysis. However, heterogeneous transesterification using a solid catalyst rather than a liquid acid or base catalyst is a more environmentally responsible way to utilize crude Jatropha oil for biodiesel production. The use of a heterogeneous catalyst also avoids neutralization and washing steps, thereby leading to a simpler and more efficient process. This paper presents an overview of the production of biodiesel from Jatropha Curcas Linnaeus (JCL) using a heterogeneous catalyst. This review also includes the current economic trend of biofuel production particularly on the production of biodiesel. Different types of conventional and advanced methods like ultrasound, microwave, membrane reactor, supercritical methanol, etc., using several types of heterogeneous catalysts like calcium oxide (CaO), sulfanated zirconia alumina (SZA) and others in the JCO biodiesel transesterification process are discussed in detail. The system design of the transesterification process via process simulation and optimization are also presented. Finally, the persistent challenges facing this process are discussed. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd
On the formation of the double helix between adenine single strands at acidic pH from synchrotron radiation circular dichroism experiments
Authors: Holm Anne I. S. , Munksgaard Nielsen Lisbeth , Vrønning Hoffmann Søren , Brøndsted Nielsen Steen
Published: February 2012

Here, we present synchrotron radiation circular dichroism spectra for a series of DNA adenine strands, (dA)n, n = 2–10, 15, at acidic pH. Reference spectra of a protonated single strand, (dAH+)n, and a protonated double helix, (dAH+)n:(dAH+)n, are provided in the wavelength region from 175 to 330 nm. The largest spectral difference between single and double strands is in the vacuum ultraviolet, where a band changes sign. This new spectral feature that characterizes double helix formation may be useful for analytical purposes but also for shedding light on the underlying complexation mechanism. Furthermore, we find that a minimum of eight or nine bases in a strand is needed for two (dAH+)n strands to form a duplex. This is a relatively high number as compared with guanine quadruplex and cytosine i‐motif formation, which is likely linked to the significant Coulomb repulsion between the all‐protonated bases. Finally, spectra recorded as a function of time after sample preparation indicates that the equilibrium is slowly reached, in certain cases taking an hour or more. © 2012 Wiley Periodicals, Inc. Biopolymers 97:550–557, 2012.
Thermo‐responsive non‐woven scaffolds for “smart” 3D cell culture
Authors: Rossouw Claire L. , Chetty Avashnee , Moolman Francis Sean , Birkholtz Lyn‐Marie , Hoppe Heinrich , Mancama Dalu T.
Published: February 2012

The thermo‐responsive polymer poly(N‐isopropylacrylamide) has received widespread attention for its in vitro application in the non‐invasive, non‐destructive release of adherent cells on two dimensional surfaces. In this study, 3D non‐woven scaffolds fabricated from poly(propylene) (PP), poly(ethylene terephthalate) (PET), and nylon that had been grafted with PNIPAAm were tested for their ability to support the proliferation and subsequent thermal release of HC04 and HepG2 hepatocytes. Hepatocyte viability and proliferation were estimated using the Alamar Blue assay and Hoechst 33258 total DNA quantification. The assays revealed that the pure and grafted non‐woven scaffolds maintained the hepatocytes within the matrix and promoted 3D proliferation comparable to that of the commercially available Algimatrix™ alginate scaffold. Albumin production and selected cytochrome P450 genes expression was found to be superior in cells growing on pure and grafted non‐woven PP scaffolds as compared to cells grown as a 2D monolayer. Two scaffolds, namely, PP‐g‐PNIPAAm‐A and PP‐g‐PNIPAAm‐B were identified as having far superior thermal release capabilities; releasing the majority of the cells from the matrices within 2 h. This is the first report for the development of 3D non‐woven, thermo‐responsive scaffolds able to release cells from the matrix without the use of any enzymatic assistance or scaffold degradation. Biotechnol. Bioeng. 2012; 109:2147–2158. © 2012 Wiley Periodicals, Inc.
A model for cellulase production from Trichoderma reesei in an airlift reactor
Authors: Bannari Rachid , Bannari Abdelfettah , Vermette Patrick , Proulx Pierre
Published: February 2012

A mathematical model for cellulase production by Trichoderma reesei RUT‐C30 grown in a cellulose medium with lactose as fed batch in an airlift reactor is proposed. To describe adequately the mass transfer between the air bubbles and the broth, it uses computational fluid dynamics (CFD) including multiphase Eulerian–Eulerian formulation, with a detailed description of the bubble size distribution through the use of the population balance model (PBM) and the class method (CM). The kinetics of the biomass growth is further coupled to the fluid flow conditions using partial differential equations for all the species involved, providing detailed information of important reactor conditions such as the distribution of oxygen, cellulose, and the shear stress within the reactor over the entire period of fermentation. Predicted results agree well with the available overall measurements for a typical fed‐batch operation and detailed profiles of the predicted concentration fields are discussed from an engineering viewpoint. Biotechnol. Bioeng. 2012; 109:2025–2038. © 2012 Wiley Periodicals, Inc.
Metabolic engineering of Lactobacillus casei for production of UDP‐N‐acetylglucosamine
Authors: Rodríguez‐Díaz Jesús , Rubio‐del‐Campo Antonio , Yebra María J.
Published: February 2012

UDP‐sugars are used as glycosyl donors in many enzymatic glycosylation processes. In bacteria UDP‐N‐acetylglucosamine (UDP‐GlcNAc) is synthesized from fructose‐6‐phosphate by four successive reactions catalyzed by three enzymes: Glucosamine‐6‐phosphate synthase (GlmS), phosphoglucosamine mutase (GlmM), and the bi‐functional enzyme glucosamine‐1‐phosphate acetyltransferase/N‐acetylglucosamine‐1‐phosphate uridyltransferase (GlmU). In this work several metabolic engineering strategies, aimed to increment UDP‐GlcNAc biosynthesis, were applied in the probiotic bacterium Lactobacillus casei strain BL23. This strain does not produce exopolysaccharides, therefore it could be a suitable host for the production of oligosaccharides. The genes glmS, glmM, and glmU coding for GlmS, GlmM, and GlmU activities in L. casei BL23, respectively, were identified, cloned and shown to be functional by homologous over‐expression. The recombinant L. casei strain over‐expressing simultaneously the genes glmM and glmS showed a 3.47 times increase in GlmS activity and 6.43 times increase in GlmM activity with respect to the control strain. Remarkably, these incremented activities resulted in about fourfold increase of the UDP‐GlcNAc pool. In L. casei BL23 wild type strain transcriptional analyses showed that glmM and glmU are constitutively transcribed. By contrast, glmS transcription is down‐regulated with a 21‐fold decrease of glmS mRNA in cells cultured with N‐acetylglucosamine as the sole carbon source compared to cells cultured with glucose. Our results revealed for the first time that GlmS, GlmM, and GlmU are responsible for UDP‐GlcNAc biosynthesis in lactobacilli. Biotechnol. Bioeng. 2012; 109:1704–1712. © 2012 Wiley Periodicals, Inc.