bluuebunny/crossref_metadata_2025 huggingface dataset:
Decode Innovation Dynamics with a Seven-Stage Model (Part 3)
Authors: Lan Ping
Published: February 2024

Drawing on prior efforts to develop a 7-stage-chain-loop innovation life cycle model, this paper explains how the model can be advanced theoretically and integrated into managerial practices. When the model is applied to the typewriter industry, the paper segments the rich history of the industry, spanning over a century, into a 7-stage-chain with three loops. In broadening the horizons of theoretical innovation research, the paper proposes four themes, ranging from the measurement of innovativeness to the creation of a comprehensive innovation framework. When considering the application of the 7-stage-chain-loop model in future managerial practices, the paper offers distinct perspectives for identifying a specific innovation landscape, devising an apt innovation strategy, and overseeing chosen innovation progress. Taken together, these elements illuminate a distinct pathway for deciphering and harnessing the dynamics of innovation.
How Are Students Reacting to ChatGPT?
Authors: Lloyd T.J. , Burns Bradford
Published: February 2024

This research addresses the question of how students are responding to the spread of artificial intelligence (AI) tools with a particular reference to ChatGPT. With a general class survey and in-depth conversations with some athletic students, this paper reveals students' habits when it comes to this new technology. Furthermore, this research displays the differences between different users, particularly athletic students, and non-athletic students. The research findings provide useful guidance for understanding the usage of ChatGPT among students.
Migration of Traditional Low-Tech Hobbies to the Digital Realm: The Role of ICT and Impact of COVID-19
Authors: Bassett Jamie , Super Kara
Published: February 2024

In this paper, we examine a select set of hobbies that originated in a time before computers and the internet, to explore how these pastimes have adapted to the demands of the digital age and how the related challenges have been addressed. Our research, which incorporates a survey of over sixty individuals, reveals that, unlike previous technological advancements, information and communication technology (ICT) doesn't just alter the environments in which hobbies are pursued, but also impacts the outcomes of these pursuits. Three key findings emerged from our research: First, the Covid-19 pandemic has complicated this migration, tying it not only to convenience but also accessibility. Second, the digital transition of low-tech hobbies carries a financial cost, with a third of respondents expressing concerns about expenditure. Finally, the psychological barriers to transitioning low-tech hobbies online appear to be greater than the physical ones.
Organising a Latin-American anthology in translation under the auspices of the US State
Department in the 1940s: Translators and editor’s correspondence
Authors: Mitiyo Morinaka Eliza
Published: February 2024

Angel Flores, a Puerto Rican literary critic and translator, and Dudley Poore, a
North American poet and translator, worked together to compile literary texts from
Latin-American countries for the anthology Fiesta in November, published by
Houghton Mifflin in 1942. It was part of a translation project subsidised by the US State
Department through the Office of the Coordinator of Inter-American Affairs (OCIAA). This
article aims to unravel and analyse the process underlying the organisation of Fiesta in
November by examining OCIAA documents and Dudley Poore’s unpublished correspondence and
by looking into themes such as patronage, manipulation, censorship and policies. It
‘listens’ to the editor’s and translators’ voices to demonstrate the multifaceted practices
of an editor and a group of translators, which, in the end, converged and shaped Latin
American texts for a US audience under the auspices of the State Department in the
1940s.
Best sellers y censura franquista: las traducciones de Teresa Pàmies
Authors: Bacardí Montserrat
Published: February 2024

Después de más de treinta años de exilio, la narradora, ensayista y periodista
catalana Teresa Pàmies (Balaguer, Lérida, 1919 – Granada, 2012) llegó a Barcelona en 1971,
gracias a la obtención del premio Josep Pla por su primer libro, Testament a Praga.
A falta de otros recursos económicos, vivió del trabajo de traducir al castellano obras
seleccionadas por los editores Joan Grijalbo y los hermanos Martínez Roca, con los que
compartía una dilatada militancia marxista. Ello la convirtió en traductora «profesional» a
lo largo de la década de los setenta, hasta que la repercusión de su obra propia le permitió
devenir escritora «profesional». En siete años, de 1972 a 1978, publicó una veintena de
traducciones, casi todas del inglés, de autores actuales que en sus novelas planteaban
temáticas actuales y, sobre todo, de una cierta controversia social (el aborto, las drogas,
los matrimonios «abiertos», vidas rebeldes…). A la par, tradujo algunos ensayos que
revisitaban el pasado contemporáneo a través de protagonistas de la historia (Buffalo Bill,
Hitler o Stalin). Ya fuera por los autores y los títulos escogidos, por los editores que los
presentaban o por la trayectoria de la traductora, el caso es que muchos de estos best
sellers toparon frontalmente con las «normas» de la censura franquista, que, en la
mayoría de los casos, las autorizó tras varios trámites, informes y «revisiones»
expurgadoras, incluso más allá del final de la dictadura. Por el amplio público que podía
estar interesado en ellas, las traducciones de literatura «comercial» fueron estrictamente
vigiladas por el régimen.
#Goyas2024 o la tímida repolitización del cine español
Authors: Herrera Sánchez Sonia
Published: February 2024

El pasado 10 de febrero asistí como miembro de la Academia de las Artes y las Ciencias Cinematográficas a la 38.ª Gala de los Premios Goya que tuvo lugar en la Feria de Valladolid. A las puertas del recinto, las protestas de los agricultores se hacían sentir en forma de gritos y algún que otro insulto dirigido a las personas asistentes a la ceremonia.
Optical mapping of ground reaction force dynamics in freely behaving Drosophila melanogaster larvae
Authors: Booth Jonathan H. , Meek Andrew T. , Kronenberg Nils M. , Pulver Stefan R. , Gather Malte C.
Published: February 2024

During locomotion, soft-bodied terrestrial animals solve complex control problems at substrate interfaces, but our understanding of how they achieve this without rigid components remains incomplete. Here, we develop new all-optical methods based on optical interference in a deformable substrate to measure ground reaction forces (GRFs) with micrometre and nanonewton precision in behaving
Drosophila
larvae. Combining this with a kinematic analysis of substrate interfacing features, we shed new light onto the biomechanical control of larval locomotion. Crawling in larvae measuring ∼1 mm in length involves an intricate pattern of cuticle sequestration and planting, producing GRFs of 1-7 µN. We show that larvae insert and expand denticulated, feet-like structures into substrates as they move, a process not previously observed in soft bodied animals. These ‘protopodia’ form dynamic anchors to compensate counteracting forces. Our work provides a framework for future biomechanics research in soft-bodied animals and promises to inspire improved soft-robot design.
Continuous endosomes form functional subdomains and orchestrate rapid membrane trafficking in trypanosomes
Authors: Link Fabian , Borges Alyssa , Karo Oliver , Jungblut Marvin , Müller Thomas , Meyer-Natus Elisabeth , Krüger Timothy , Sachs Stefan , Jones Nicola G. , Morphew Mary , Sauer Markus , Stigloher Christian , McIntosh J. Richard , Engstler Markus
Published: February 2024

Endocytosis is a common process observed in most eukaryotic cells, although its complexity varies among different organisms. In
Trypanosoma brucei
, the endocytic machinery is under special selective pressure because rapid membrane recycling is essential for immune evasion. This unicellular parasite effectively removes host antibodies from its cell surface through hydrodynamic drag and fast endocytic internalization. The entire process of membrane recycling occurs exclusively through the flagellar pocket, an extracellular organelle situated at the posterior pole of the spindle-shaped cell. The high-speed dynamics of membrane flux in trypanosomes do not seem compatible with the conventional concept of distinct compartments for early, late and recycling endosomes. To investigate the underlying structural basis for the remarkably fast membrane traffic in trypanosomes, we employed advanced techniques in light and electron microscopy to examine the three-dimensional architecture of the endosomal system. Our findings reveal that the endosomal system in trypanosomes exhibits a remarkably intricate structure. Instead of being compartmentalized, it constitutes a continuous membrane system, with specific functions of the endosome segregated into membrane subdomains enriched with classical markers for early, late, and recycling endosomes. These membrane subdomains can partly overlap or are interspersed with areas that are negative for endosomal markers. This continuous endosome allows fast membrane flux by facilitated diffusion that is not slowed by multiple fission and fusion events.
The embryonic role of juvenile hormone in the firebrat, Thermobia domestica, reveals its function before its involvement in metamorphosis
Authors: Truman James W. , Riddiford Lynn M. , Konopová Barbora , Nouzova Marcela , Noriega Fernando G. , Herko Michelle
Published: February 2024

To gain insights into how juvenile hormone (JH) came to regulate insect metamorphosis, we studied its function in the ametabolous firebrat,
Thermobia domestica
. Highest levels of JH occur during late embryogenesis, with only low levels thereafter. Loss-of-function and gain-of-function experiments show that JH acts on embryonic tissues to suppress morphogenesis and cell determination and to promote their terminal differentiation. Similar embryonic actions of JH on hemimetabolous insects with short germ band embryos indicate that JH’s embryonic role preceded its derived function as the postembryonic regulator of metamorphosis. The postembryonic expansion of JH function likely followed the evolution of flight. Archaic flying insects were considered to lack metamorphosis because tiny, movable wings were evident on the thoraces of young juveniles and their positive allometric growth eventually allowed them to support flight in late juveniles. Like in
Thermobia
, we assume that these juveniles lacked JH. However, a postembryonic reappearance of JH during wing morphogenesis in the young juvenile likely redirected wing development to make a wing pad rather than a wing. Maintenance of JH then allowed wing pad growth and its disappearance in the mature juvenile then allowed wing differentiation. Subsequent modification of JH action for hemi- and holometabolous lifestyles are discussed. The likely action of this sesquiterpene hormone as a morphogenesis-to-differentiation switch in archaic embryos preadapted it for later assuming its function as the
status quo
regulator of insect metamorphosis.
Post-fertilization transcription initiation in an ancestral LTR retrotransposon drives lineage-specific genomic imprinting of ZDBF2
Authors: Kobayashi Hisato , Igaki Tatsushi , Kumamoto Soichiro , Tanaka Keisuke , Takashima Tomoya , Suzuki Shunsuke , Hayashi Masaaki , Renfree Marilyn B. , Kawahara Manabu , Saito Shun , Kobayashi Toshihiro , Nagashima Hiroshi , Matsunari Hitomi , Nakano Kazuaki , Uchikura Ayuko , Kiyonari Hiroshi , Kaneko Mari , Imai Hiroo , Nakabayashi Kazuhiko , Lorincz Matthew C. , Kurimoto Kazuki
Published: February 2024

The imprinted
ZDBF2
gene is controlled by oocyte-derived DNA methylation, but its regulatory system is quite different from that of other canonically imprinted genes that are dependent on DNA methylation deposited in the gametes. At the
ZDBF2
locus, maternal DNA methylation in the imprinted differentially methylated region (DMR) does not persist after implantation. Instead, a transient transcript expressed in the early embryo exclusively from the unmethylated paternal allele of the DMR, known as
GPR1-AS
, contributes to establishing secondary DMRs that maintain paternal expression of
ZDBF2
in the somatic lineage. While the imprinting of
ZDBF2
and its unique regulatory system are evident in humans and mice, whether this process is conserved in other mammals has not been addressed. Here, we show that the first exon of human
GPR1-AS
overlaps with that of a long terminal repeat (LTR) belonging to the MER21C subfamily of retrotransposons. Although this LTR family appears and is amplified in eutherians, the MER21C insertion into the
GPR1-AS
orthologous region occurred specifically in the common ancestor of Euarchontoglires, a clade that includes primates, rodents, and rabbits. Directional RNA sequencing of placental tissues from various mammalian species revealed
GPR1-AS
orthologs in rabbits and nonhuman primates, with their first exon embedded within the same ancestral LTR. In contrast, allele-specific expression profiling showed that cow and tammar wallaby, mammals outside the Euarchontoglires group, expressed both alleles in all tissues analyzed. Our previous studies showed that LTRs reactivated in oocytes drive lineage-specific imprinting during mammalian evolution. The data presented here suggest that LTR-derived sequence activation after fertilization can also contribute to the lineage-specific establishment of imprinted genes.
Lipid discovery enabled by sequence statistics and machine learning
Authors: Christensen Priya M. , Martin Jonathan , Uppuluri Aparna , Joyce Luke R. , Wei Yahan , Guan Ziqiang , Morcos Faruck , Palmer Kelli L.
Published: February 2024

Bacterial membranes are complex and dynamic, arising from an array of evolutionary pressures. One enzyme that alters membrane compositions through covalent lipid modification is MprF. We recently identified that
Streptococcus agalactiae
MprF synthesizes lysyl-phosphatidylglycerol (Lys-PG) from anionic PG, and a novel cationic lipid, lysyl-glucosyl-diacylglycerol (Lys-Glc-DAG), from neutral glycolipid Glc-DAG. This unexpected result prompted us to investigate whether Lys-Glc-DAG occurs in other MprF-containing bacteria, and whether other novel MprF products exist. Here, we studied protein sequence features determining MprF substrate specificity. First, pairwise analyses identified several streptococcal MprFs synthesizing Lys-Glc-DAG. Second, a restricted Boltzmann machine-guided approach led us to discover an entirely new substrate for MprF in
Enterococcus
, diglucosyl-diacylglycerol (Glc2-DAG), and an expanded set of organisms that modify glycolipid substrates using MprF. Overall, we combined the wealth of available sequence data with machine learning to model evolutionary constraints on MprF sequences across the bacterial domain, thereby identifying a novel cationic lipid.
The association between urbanization and adolescent depression in China
Authors: Pan Degong , Yan Ning , Pu Lining , He Xiaoxue , Wang Huihui , Zhang Xue , Shi Xiaojuan , Wen Jing , Li Jiangping
Published: February 2024

Background

With the rapid urbanization in many countries, more attention is being paid to the relationship between urbanization and mental health, especially depression. However, in countries with rapid urbanization, few empirical studies exist on the relationship between urbanization and adolescent depression.

Methods

Nationally representative survey data from the China Family Panel Studies in 2012, 2016 and 2018 were used. Data of 1,588 adolescents were obtained from 25 provinces. Depression was measured using the Center for Epidemiology Studies of Depression 20-item score. The urbanization rate was obtained from the National Bureau of Statistics of China. The generalized estimating equation was used to estimate the statistical relationship.

Results

The participants’ mean age at baseline was 15 years, and 51.2% (813/1,588) of participants were male. After adjusting for all covariates (gender, age, ethnicity, level of education, marital status, urban/rural areas, body mass index, self-rated health, academic pressure, smoking, drinking and exercise), the rate of urbanization was monotonically and negatively associated with adolescent depression (odds ratio 0.34, 95% CI [0.14–0.79]). Compared with female adolescents, male adolescents had a lower risk of depression (odds ratio 0.80, 95% CI [0.67–0.97]).

Conclusion

In the context of China, urbanization has a positive effect on the mental health of adolescents. Female adolescents are more likely to experience depression than male adolescents.
Color components determination and full-length comparative transcriptomic analyses reveal the potential mechanism of carotenoid synthesis during Paphiopedilum armeniacum flowering
Authors: Bai Yiwei , Ma Jiping , Ma Yanjun , Chang Yanting , Zhang Wenbo , Deng Yayun , Zhang Na , Zhang Xue , Fan Keke , Hu Xiaomeng , Wang Shuhua , Jiang Zehui , Hu Tao
Published: February 2024

Background

Paphiopedilum armeniacum (P. armeniacum), an ornamental plant native to China, is known for its distinctive yellow blossoms. However, the mechanisms underlying P. armeniacum flower coloration remain unclear.

Methods

We selected P. armeniacum samples from different flowering stages and conducted rigorous physicochemical analyses. The specimens were differentiated based on their chemical properties, specifically their solubilities in polar solvents. This key step enabled us to identify the main metabolite of flower color development of P. armeniacum, and to complete the identification by High-performance liquid chromatography (HPLC) based on the results. Additionally, we employed a combined approach, integrating both third-generation full-length transcriptome sequencing and second-generation high-throughput transcriptome sequencing, to comprehensively explore the molecular components involved.

Results

We combined physical and chemical analysis with transcriptome sequencing to reveal that carotenoid is the main pigment of P. armeniacum flower color. Extraction colorimetric method and HPLC were used to explore the characteristics of carotenoid accumulation during flowering. We identified 28 differentially expressed carotenoid biosynthesis genes throughout the flowering process, validated their expression through fluorescence quantification, and discovered 19 potential positive regulators involved in carotenoid synthesis. Among these candidates, three RCP2 genes showed a strong potential for governing the PDS and ZDS gene families. In summary, our study elucidates the fundamental mechanisms governing carotenoid synthesis during P. armeniacum flowering, enhancing our understanding of this process and providing a foundation for future research on the molecular mechanisms driving P. armeniacum flowering.
Eficiência na produção de madeira e a seleção de espécies de árvores brasileiras
Authors: Santos Ricardo Augusto Oliveira , Fonseca Simone Evangelista
Published: February 2024

O estudo buscou analisar e selecionar espécies tropicais brasileiras com a maior eficiência produtiva. Utilizou-se a metodologia de Análise Envoltória de Dados - DEA para mensurar o índice de eficiência relativa presente na relação produtiva do plantio e cultivo de espécies tropicais brasileiras usadas para produção de madeira serrada. Na pesquisa foram consideradas 18 espécies tropicais nativas do Brasil como Guanandi, Cassia Rosea, Mogno, Pau de Ferro do Sul, Cedro, Vassourão Graudo, Maria Preta, Canela Guaicá, Ângico Gurucaia, Barú, Cajarana, Aribá Amarelo, Amendoim, Santa Rita, Ingá Ferradura, Louro Pardo, Faveira Benguê e Ângico Branco. Variáveis técnicas publicadas pela EMBRAPA em comunicados, informações de espaçamento, fuste e DAP foram utilizadas para calcular a capacidade de transformação produtiva dos insumos em produtos de cada espécie. Guanandi, Cassia Rosea, Mogno, Pau de Ferro do Sul e Cedro foram às espécies que alcançaram índices máximos de eficiência em relação à média dos anos analisados. Diante do exposto o trabalho contribui para a escolha ótima da espécie tropical que possui melhor produtividade madeireira.
Standardization on Effect of Storage and Packaging Materials on Shelf Life and Quality of Ridge Gourd (Luffa acutangula L.)
Authors: Sushma K. , Padma M. , Rajkumar M. , Goud Ch. Raja , Kumar B. Naveen , Gouthami P
Published: February 2024

An experiment was conducted on ‘‘Standardization on effect of storage and packaging materials on shelf life and quality of ridge gourd (Luffa acutangula L)’’ during Kharif 2021 and Summer 2022 on shelf life and quality of ridge gourd at PG laboratory, College of Horticulture, Rajendranagar. The experiment design is factorial completely randomized design with eight packaging materials as factor-1 and three elite treatments as factor-2 with a total of twenty four (24) treatments replicated thrice. The results revealed that, the Polyethylene 200 gauge with 2% vent and Vermicompost 12 t/ha + Arka microbial consortium recorded lowest physiological loss in weight, titrable acidity and highest shelf life, TSS, ascorbic acid, firmness, chlorophyll content with increase in days of storage.
Analysis of Historical and Future Rainfall Projections in India's Lower Godavari Basin
Authors: Sravani A. , Sujatha N. , Rao L. V. , Rao V. Lakshmana
Published: February 2024

Changes in evaporation and precipitation in the climate are precursors to changes in the water cycle due to the increase in temperatures due to climate change. In recent years, enormous changes in precipitation patterns have led to an increase in extreme rainfall events, reflecting flash floods in smaller areas. To understand this, you must study the rainfall patterns of the district and the smaller watersheds. In the present study, we have observed the trend of rainfall in the lower Godavari basin, which was part of the Godavari River from 1970 to 2019, using IMD 0.25X0.25 ° gridded rainfall data. According to the study, during the winter season and before the monsoon, there is no significant increasing or decreasing trend. In the post-monsoon season they are showing a negative and decreasing trend with a magnitude of 4 mm/year. But in the monsoon season, one end (the right end near the river mouth) of the basin or watershed is showing an increasing trend, while the left part is showing a significantly decreasing trend. In addition to that, future projections of the CMIP5 two scenarios data from 2000 to 2100 to understand the precipitation patterns in future projections. Lower Godavari basin from 2020–2040 and 2040-2100 with the RCP 4.5 and RCP 8.5 scenarios. With the RCP 4.5 scenario, the first 40 years (2020–2040) of the future projected mean seasonal rainfall are 4.5 mm/year higher in the western part of the sub-basin than in the eastern and river mouth regions.
The Use of Immersion Oil in Parasitology Light Microscopic Examination
Authors: Siagian Forman Erwin
Published: February 2024

Aims: to briefly review the history of application of immersion oil and specifically in some Parasitology Microscopic examination.

Discussion: One way of increasing the optical resolving power of the microscope is to use immersion liquids between the front lens of the objective and the cover slip. The application of immersion oil in microscopic examination began in the mid-17th century. The principle of immersion oil in microscopic examination is to improve the resolution and clarity of the image by reducing the refractive index mismatch between the specimen and the objective lens. In the context of micro-sized parasitic agent, adding this oil will greatly enhanced visualization and in turn will have a direct impact on improving the characteristic morphological image/appearance, thereby enabling observers to optimize microscopic assessment for parasitological examination. Protozoan parasites such as Plasmodium spp, Entamoeba histolytica, Giardia lamblia, Microsporidia spp., Trichomonas vaginalis, Toxoplasma spp, Trypanosoma spp, Babesia spp, Leishmania spp, Cyclospora cayetanensis, and Blastocystis hominis are some examples of parasitic organisms that should be viewed at great magnification to see detailed morphology; and for that it means you need to add immersion oil.

Conclusion: The addition of immersion oil in Paarasitology microscopic examination is surely improve optical resolution and clarity of the image and positively support Parasitologist to make correct diagnosis.
Surface‐binding autoantibodies to cerebellar neurons in opsoclonus syndrome
Authors: Blaes Franz , Fühlhuber Verena , Korfei Martina , Tschernatsch Marlene , Behnisch Wolfgang , Rostasy Kevin , Hero Barbara , Kaps Manfred , Preissner Klaus T.
Published: June 2005

Childhood opsoclonus‐myoclonus syndrome can occur with or without associated neuroblastoma. An autoimmune pathogenesis has been discussed for both forms. We show here that the majority of children with opsoclonus‐myoclonus syndrome (10/14) have autoantibodies binding to the surface of isolated rat cerebellar granular neurons. In some patients, these antibodies are masked by IgG binding to ubiquitous surface antigens, which could be removed by preincubation with the nonneuronal control cell line HEK 293. A newly introduced competitive binding assay showed that the surface binding is directed against the same autoantigen in different patients. Therefore, we hypothesize that opsoclonus‐myoclonus syndrome may be the result of an autoimmune process against a neuronal surface protein. Ann Neurol 2005
Role of 1,10‐phenanthroline and ortho phosphoric acid on graft polymerization of vinyl monomers from poly (vinyl alcohol) in the presence of Fenton's reagent
Authors: Chowdhury P. , Ali Md. A.
Published: June 2005

The effect and role of 1,10‐phenanthroline (o‐phen) and ortho phosphoric acid on graft polymerization of vinyl monomers from poly (vinyl alcohol) (PVA) in the presence of Fenton's reagent have been studied. Reaction conditions were optimized. Fourier transform infrared (FT‐IR) spectra were used for confirmation of grafting. A probable mechanism of grafting to elucidate the role of phenanthroline and phosphoric has been suggested. Thermal properties of the grafted polymer were studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2335–2339, 2005
Tensile properties and stress whitening of polypropylene/polyolefin elastomer/magnesium hydroxide flame retardant composites for cable insulating application
Authors: Hong Chae Hwan , Lee Yong Bum , Bae Jin Woo , Jho Jae Young , Uk Nam Byeong , Chang Do‐Hoon , Yoon Seoung‐Hoon , Lee Kun‐Joo
Published: June 2005

Flame retardant polypropylene (PP) composites were prepared by combining random polypropylene with uncoated and surface‐treated forms of magnesium hydroxide filler and elastomeric modifiers, with and without maleic anhydride functionalization. Four types of magnesium hydroxide (MDH) with different surface treatments were compounded at amounts up to 60% by weight to PP/polyolefin elastomer (POE) matrix resin to obtain a series of composites. The tensile strength and elongation at break were measured. MDH coated with polymeric material was found to give a high elongation at break value compared with the values obtained with uncoated and vinyl silane and amino silane coated MDH. Two types of POE, i.e., neat and maleic anhydride grafted POE (POEgMA), were used to investigate the stress whitening of composites in bending deformation. POEgMA used composites showed no stress whitening while neat POE used composites showed whitening when bended. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2311–2318, 2005
Epoxy‐silica nanocomposites: Preparation, experimental characterization, and modeling
Authors: Bondioli Federica , Cannillo Valeria , Fabbri Elena , Messori Massimo
Published: June 2005

Silica nanoparticles having different sizes were obtained by the sol‐gel process and characterized. The prepared nanoparticles were subsequently used as reinforcing fillers to prepare epoxy‐based composites with a silica content ranging from 1 to 5 wt %. SEM analysis and tensile tests carried out on the silica‐epoxy nanocomposites indicated the absence of particle aggregation and a reinforcing effect in terms of increased elastic modulus. Mechanical properties were also modeled by using a finite element code able to construct a numerical model from a microstructural image of the material. A more reliable model was prepared by considering the presence of an interphase layer surrounding the particles with intermediate elastic properties between the epoxy and the inclusions and a characteristic size proportional to the particle radius. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2382–2386, 2005
Glass‐transition temperature based on dynamic mechanical thermal analysis techniques as an indicator of the adhesive performance of vinyl ester resin
Authors: Herzog Benjamin , Gardner Douglas J. , Lopez‐Anido Roberto , Goodell Barry
Published: June 2005

Vinyl ester resins are being used extensively as matrices in fiber‐reinforced polymer composite materials, but their use as a structural adhesive has been limited. Initial studies investigating the durability of a vinyl ester as a wood adhesive showed unsatisfactory performance in comparison with other adhesives. In this work, the glass‐transition temperatures (Tg's) of a vinyl ester and a E‐glass/vinyl ester composite material, fabricated by the Composites Pressure Resin Infusion System, were determined with dynamic mechanical thermal analysis. The results indicated that the resin cured under ambient conditions had a much lower Tg (∼60°C) than the postcured material (∼107°C). This suggested undercuring, that is, incomplete crosslinking, of the resin when it was cured at room temperature. E‐glass/vinyl ester samples, however, showed virtually no difference in Tg between room‐temperature‐cured and postcured samples. The exact reasons for this are not currently known but are thought to be both mechanical and chemical in nature. On the basis of the findings presented in this article, it can be concluded that if this vinyl ester resin is to be used as a structural adhesive, postcuring or formulation to ensure a high degree of crosslinking under ambient conditions is necessary. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2221–2229, 2005
Synthesis and mesomorphic properties of side‐chain cholesteric liquid‐crystalline polysiloxanes
Authors: Zheng Ying‐Ying , Li Qian‐Yue , Zhang Bao‐Yan , Zhang Li‐Feng
Published: June 2005

A series of new side‐chain cholesteric liquid‐crystalline polysiloxanes was synthesized by grafting copolymerization. The chemical structures of the obtained monomers and polymers were confirmed by Fourier transform infrared or 1H‐NMR spectroscopy. The mesomorphic properties were investigated with differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the content of cholesteryl 4‐allyloxybenzoate on the phase behavior of the polymers was examined. The monomer 4‐(undec‐10‐en‐1‐yloxy)‐4′‐(4‐ethoxybenzoyloxy)biphenyl showed nematic and smectic (A, C, and B) phases upon cooling, and cholesteryl 4‐allyloxybenzoate revealed an enantiotropic cholesteric phase. One polymer showed a nematic schlieren texture, other polymers showed cholesteric Grandjean and oily‐streak textures, and another polymer showed a smectic fan‐shaped texture. The experimental results demonstrated that the glass‐transition temperature and clearing temperature decreased first and then increased with an increasing content of cholesteryl 4‐allyloxybenzoate. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2392–2398, 2005
Coefficient of friction reduction of ethylene‐co‐acrylic acid film: Effects of grafted 12‐aminododecanamide and solvent exposure
Authors: Luo Ning , Janorkar Amol V. , Hirt Douglas E. , Husson Scott M. , Schwark Dwight W.
Published: June 2005

The effect of covalently bound 12‐aminododecanamide on the surface coefficient of friction (COF) of ethylene–acrylic acid copolymer (EAA) films was investigated. The reaction involved grafting 12‐aminododecanoic acid to the inherent carboxylic acid groups on the film, followed by amidation of the grafted amino acid. Conversion of film carboxylic acid groups to primary amide groups was also conducted to compare the impact of direct surface amidation. Subsequent measurements showed that both surface amidation schemes reduced the kinetic COF from 0.30 to 0.15 ∼ 0.18. Repetitive COF testing revealed that amide‐modified EAA films maintained low COF values that were independent of the number of COF test runs. However, control experiments showed that COF values also depended greatly on simply exposing film to the various reaction solvents, which increased surface roughness. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2242–2248, 2005
Characterization of polyamideamine‐epichlorohydrin (PAE) resin: Roles of azetidinium groups and molecular mass of PAE in wet strength development of paper prepared with PAE
Authors: Obokata Takao , Yanagisawa Masahiro , Isogai Akira
Published: June 2005

Polyamideamine‐epichlorohydrin (PAE) resin is a crosslinked heteropolymer having cationic charges, and has been widely used as a wet strength agent of paper in the papermaking process. In this study, more accurate molecular mass values of PAE were determined by size exclusion chromatography attached with a multi angle laser light scattering detector (SEC‐MALS). The obtained weight average molecular mass (Mw) values of commercial and laboratory‐made PAE samples were 1,140,000 and 494,000, respectively, and these values were much higher than those reported so far. SEC‐MALS analysis also revealed that PAE molecules had highly crosslinked structures and extremely wide molecular mass distributions. Molecular mass values and content of 3‐hydroxy‐azetidinium (AZR) groups in PAE and PAE intermediates during the course of PAE synthesis were also determined by the SEC‐MALS and 1H NMR methods, and the relationships between these values and the wet strength development of handsheets prepared with these PAE samples were studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2249–2255, 2005
Modification of novolac resin by interpenetrating network formation with poly(butyl acrylate)
Authors: Goswami S. , Nad S. , Chakrabarty D.
Published: June 2005

Interpenetrating networks (IPNs) of novolac (phenol formaldehyde) resin and poly(butyl acrylate) (PBA) were prepared by a sequential mode of polymerization. Both full IPNs and semi‐IPNs of different compositions were synthesized and characterized with respect to their mechanical properties, that is, their modulus, ultimate tensile strength (UTS), elongation‐at‐break percentage, and toughness. Their thermal properties were examined with differential scanning calorimetry and thermogravimetric analysis (TGA). A morphological study was performed with an optical microscope. The effects of the variation of the blend ratios on the aforementioned properties were studied. There was a gradual decrease in the modulus and UTS with a simultaneous increase in the elongation‐at‐break percentage and toughness for both types of IPNs as the proportions of PBA were increased. With increasing proportions of PBA, the glass‐transition temperatures of the different IPNs underwent shifts toward a lower temperature region. This showed a plasticizing influence of PBA on the rigid and brittle phenolic matrix. TGA thermograms depicted the classical two‐step degradation for the phenolic resin. Although there was an apparent increase in the thermal stability at the initial stage (up to 350°C), particularly at lower temperatures, a substantial decrease in the thermal stability was observed at higher temperatures under study. In all the micrographs of full IPNs and semi‐IPNs, two‐phase structures were observed, regardless of the PBA content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2407–2417, 2005
Influence of branching characteristics on thermal and mechanical properties of Ziegler–Natta and metallocene hexene linear low‐density polyethylene blends with low‐density polyethylene
Authors: Hussein Ibnelwaleed A. , Hameed Tayyab
Published: June 2005

The effect of the branch content (BC) and composition distribution (CD) of linear low‐density polyethylene (LLDPE) on the thermal and mechanical properties of its blends with LDPE were studied. All blends and pure resins were conditioned in a Haake PolyDrive blender at 190°C and in the presence of adequate amounts of antioxidant. Two metallocene LLDPEs (m‐LLDPE) and one Ziegler–Natta (ZN) hexene LLDPE were melt blended with the same LDPE. The effect of the BC was investigated by blending two hexene m‐LLDPEs of similar weight‐average molecular weights and molecular weight distributions but different BCs with the same LDPE. The effect of the CD was studied by using a ZN and an m‐LLDPE with similar weight‐average molecular weights, BCs, and comonomer type. Low‐BC m‐LLDPE blends showed separate crystallization whereas cocrystallization was observed in the high‐BC m‐LLDPE‐rich blends. However, ZN‐LLDPE/LDPE blends showed separate crystallization together with a third population of cocrystals. The influence of the crystallization behavior was reflected in the mechanical properties. The BC influenced the modulus, ultimate tensile strength, and toughness. The addition of a small amount of LDPE to a low‐BC m‐LLDPE resulted in a major improvement in the toughness, whereas the results for the high‐BC pair followed the additivity rule. ZN‐LLDPE blends with LDPE blends were found to be more compatible and exhibited superior mechanical properties compared to m‐LLDPE counterparts with the same weight‐average molecular weight and BC. All mechanical properties of ZN‐LLDPE blends follow the linear rule of mixtures. However, the CD had a stronger influence on the mechanical properties in comparison to the BC. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2488–2498, 2005
Processing–structure–properties relationships of mechanically and thermally enhanced smectite/epoxy nanocomposites
Authors: Kotsilkova R.
Published: June 2005

Mechanically reinforced and thermally enhanced smectite/epoxy nanocomposites were synthesized using “direct” (without solvent) and “solvent” processing techniques. The molecular dispersion of smectite clay in the epoxy resin was investigated for its role in the rheology, structure formation, and properties of nanocomposites. The effects of three types of organic modifiers on the dispersion structure were compared. The use of solvent during processing assists in the enhancement of clay exfoliation. Rheology was used as a method to compare the degree of clay delamination in the resin matrix, as well as to estimate the suspension structure. The critical volume fraction (Φ*) and maximal packaging of smectites were determined and used for prediction of the viscosity. The qualitative changes in the nanostructure of suspensions above Φ*, due to flocculation of exfoliated clay layers, were compared with the alteration of the properties of nanocomposites, related to the structure formation and morphology. The curing kinetics were found to depend on both the organic modifier and solvent, but the extent of curing was roughly equivalent for the pure epoxy resin and the nanocomposites. The structure of the nanocomposites, either intercalated or exfoliated, produced by the direct processing technique was controlled by the organic modifier. By using solvent processing, the effect of the solvent dominates that of the organic modifier, presumably leading to exfoliated nanocomposites. The mechanical and thermal properties are strongly enhanced above the Φ* of smectites, and they are significantly dependent on the type of nanocomposite structure and the use of solvent. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2499–2510, 2005
Effects of molecular weight on phase structure of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends
Authors: Takahashi Mizuho , Ito Masayoshi , Ida Shinichiro , Ikawa Tokimitsu
Published: June 2005

The phase structure of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends was studied in relation to the molecular weight. The samples were prepared by both solution blends, which showed two glass‐transition temperatures (Tg), and melt blends (MQ), which showed a single Tg, depending on the composition of the blends. The Tg of the MQ series was independent of the molecular weight of the homopolymer, although the degree of transesterification in the blends was affected by the molecular weight. The MQ series showed two exotherms during the heating process of a differential scanning calorimetry scan. The peak temperature and the heat flow of the exotherms were affected by the molecular weight of the homopolymers. The strain‐induced crystallization of the MQ series suggested the independent crystallization of PET and PEN. Based on the results, a microdomain structure of each homopolymer was suggested. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2428–2438, 2005
Thermal and crystallization behavior of hydrogen‐bonded miscible blend of poly(3‐hydroxybutyrate) and enzymatically polymerized polyphenol
Authors: Li Jianchun , Fukuoka Tokuma , He Yong , Uyama Hiroshi , Kobayashi Shiro , Inoue Yoshio
Published: June 2005

Enzymatically prepared novel polyphenol poly(4,4′‐dihydroxydiphenyl ether) (PDHDPE) is blended to modify the properties of biodegradable polyester poly[(R)‐3‐hydroxybutyrate] (PHB). Because the differential scanning calorimetry data show a single composition‐dependent glass transition for each blend, PHB and PDHDPE are found to be miscible in the amorphous phase. The crystallization of PHB is depressed by PDHDPE because PDHDPE reduces the molecular mobility and the flexibility of molecular chains of PHB. The Fourier transform IR spectra clearly indicate that PHB and PDHDPE interact through strong intermolecular hydrogen bonds between the carbonyl groups of PHB and the hydroxyl groups of PDHDPE. However, when PHB is blended with DHDPE monomer, no obvious hydrogen bonds are observed because of the phase separation and strong self‐intermolecular hydrogen bonds between DHDPE molecules. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2439–2449, 2005
Physical properties of crosslinked cellulose catalyzed with nano titanium dioxide
Authors: Wang Chyung‐Chyung , Chen Cheng‐Chi
Published: June 2005

Four different carboxylic acids, 1,2,3,4‐butane tetracarboxylic acid (BTCA), maleic acid (MA), succinic acid (SUA), and citric acid (CA), were used as crosslinking agents to treat cotton fabrics in the presence of nanometer titanium dioxide (TiO2) as a catalyst under UV irradiation. The dry crease recovery angle (DCRA) and wet crease recovery angle (WCRA) values of the treated fabrics were ranked BTCA > MA > CA > SUA and the tensile strength retention (TSR) values were ranked BTCA < MA < CA < SUA at a given resin concentration, catalyst concentration, and irradiation time period. The physical properties of the treated fabrics for nanometer silver/nanometer titanium dioxide (Ag/TiO2) catalyst showed the same tendency. At a given DCRA, the WCRA values were ranked in the order BTCA ≒ MA > CA ≒ SUA; and at a given value of the TSR, the WCRA and DCRA values were both ranked in the order BTCA > MA > CA > SUA. The softness values of the carboxylic acid treated fabrics in the presence of nanometer TiO2 catalyst were all better than that of the untreated fabric. Surface deposition of the treated fabrics for BTCA, which contains one vinyl double bond and four carboxylic acid groups, was higher than that for CA, which contains no vinyl double bond. IR spectra and electron spectroscopy for chemical analysis survey spectra showed the ester bond crosslink between the cellulose molecule and the various acids used in this study. The values of DCRA, WCRA, and add‐on of the CA crosslinked fabrics for the mixed catalysts were in the order ZrO2/TiO2 < SiO2/TiO2 < Ag/TiO2. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2450–2456, 2005
Photografting of N‐isopropylacrylamide and glycidyl methacrylate binary monomers on polyethylene film: Effect of mixed solvent consisting of water and organic solvent
Authors: Irwan Ginting Suka , Aoyama Yoichi , Kuroda Shin‐ichi , Kubota Hitoshi , Kondo Takashi
Published: June 2005

Photografting (λ > 300 nm) of N‐isopropylacrylamide (NIPAAm) and glycidyl methacrylate (GMA) binary monomers (NIPAAm/GMA) on low‐density polyethylene film (thickness = 30 μm) was investigated at 60°C using mixed solvent consisting of water and an organic solvent such as acetone. Xanthone was used as a photoinitiator by coating it on the film surfaces. A maximum percentage of grafting was observed at a certain concentration of acetone in the mixed solvent, which was commonly observed for both ratios of NIPAAm/GMA, 8/2 and 7/3. Based on the photografting of NIPAAm/GMA on xanthone‐coated film, monomer reactivity ratios of NIPAAm (r1) and GMA (r2) were calculated using the Fineman–Ross method. The values were 0.31 ± 0.1 and 4.8 ± 0.2 for the water solvent system, while they were 0.96 ± 0.1 and 4.9 ± 0.1 for the mixed solvent system. NIPAAm/GMA‐grafted films with a homogeneous distribution of grafted chains were formed by photografting using water and mixed solvents. The NIPAAm/GMA‐grafted films exhibited temperature‐responsive characters, whereas the grafted films showed a reversible change in the degree of swelling between 0 and 50°C, respectively. Epoxy groups in the grafted poly(NIPAAm/GMA) chains could be aminated with ethylenediamine in N,N′‐dimethylformamide at 70°C for 3 h. Complexes of the aminated NIPAAm/GMA‐grafted chains with cupric ion exhibited catalytic activity for the decomposition of hydrogen peroxide at 20 to 50°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2469–2475, 2005
Hydration of lysozyme as observed by infrared spectrometry
Authors: Liltorp K. , Maréchal Y.
Published: June 2005

Infrared spectra of a film of lysozyme 3 μm thick, immersed in an atmosphere displaying a relative humidity, or hygrometry, which spans the whole range from 0 to 1 at room temperature, are recorded. The evolution of the spectra with this relative humidity is quantitatively analyzed on the basis of a newly proposed method. It allows the precise measurement of the quantity of water that remains embedded inside the dried sample at each stage of hydration, and the definition, in terms of chemical reactions of the three hydration mechanisms that correspond to the three hydration spectra on which all experimental spectra can be decomposed. With respect to preceding similar studies, some refinements are introduced that allow improvement of the interpretation, but that also raise some new questions, which mainly concern the structure of the hydrogen‐bond network around the carbonyl peptide groups. © 2005 Wiley Periodicals, Inc. Biopolymers 79: 185–196, 2005

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Effects from Hydrogen Bonds on Water Structure in (H3O)2 [Mo6Cl8X6]×yH2O X: Cl (y = 7), Br (y = 6), or I (y = 6).
Authors: Flemstroem A. , Hirsch T. K. , Sehlstedt L. , Lidin S. , Ojamae L.
Published: June 2005

For Abstract see ChemInform Abstract in Full Text.
Pb3Mn5V2O16: A New Lead Manganese Vanadate with Double MnII/MnIV Valence.
Authors: Henry Natacha , Burylo‐Dhuime Laurence , Abraham Francis , Mentre Olivier
Published: June 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis and Energetics of Yellow TaON.
Authors: Orhan Emmanuelle , Tessier Franck , Marchand Roger
Published: June 2005

For Abstract see ChemInform Abstract in Full Text.
Antifluorite to Ni2In‐Type Phase Transition in K2S at High Pressures.
Authors: Vegas Angel , Grzechnik Andrzej , Hanfland Michael , Muehle Claus , Jansen Martin
Published: June 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of Bulk and Alumina‐Supported Bimetallic Carbide and Nitride Catalysts.
Authors: Korlann Scott , Diaz Brian , Bussell Mark E.
Published: June 2005

For Abstract see ChemInform Abstract in Full Text.