bluuebunny/crossref_metadata_2025 huggingface dataset:
The Neuron-specific IIS/FOXO Transcriptome in Aged Animals Reveals Regulatory Mechanisms of Cognitive Aging
Authors: Weng Yifei , Zhou Shiyi , Morillo Katherine , Kaletsky Rachel , Lin Sarah , Murphy Coleen T.
Published: June 2024

Cognitive decline is a significant health concern in our aging society. Here, we used the model organism
C. elegans
to investigate the impact of the IIS/FOXO pathway on age-related cognitive decline. The
daf-2
Insulin/IGF-1 receptor mutant exhibits a significant extension of learning and memory span with age compared to wild-type worms, an effect that is dependent on the DAF-16 transcription factor. To identify possible mechanisms by which aging
daf-2
mutants maintain learning and memory with age while wild-type worms lose neuronal function, we carried out neuron-specific transcriptomic analysis in aged animals. We observed downregulation of neuronal genes and upregulation of transcriptional regulation genes in aging wild-type neurons. By contrast, IIS/FOXO pathway mutants exhibit distinct neuronal transcriptomic alterations in response to cognitive aging, including upregulation of stress response genes and downregulation of specific insulin signaling genes. We tested the roles of significantly transcriptionally-changed genes in regulating cognitive functions, identifying novel regulators of learning and memory. In addition to other mechanistic insights, comparison of the aged vs young
daf-2
neuronal transcriptome revealed that a new set of potentially neuroprotective genes is upregulated; instead of simply mimicking a young state,
daf-2
may enhance neuronal resilience to accumulation of harm and take a more active approach to combat aging. These findings suggest a potential mechanism for regulating cognitive function with age and offer insights into novel therapeutic targets for age-related cognitive decline.
Multiplexed assays of human disease-relevant mutations reveal UTR dinucleotide composition as a major determinant of RNA stability
Authors: Su Jia-Ying , Wang Yun-Lin , Hsieh Yu-Tung , Chang Yu-Chi , Yang Cheng-Han , Kang YoonSoon , Huang Yen-Tsung , Lin Chien-Ling
Published: June 2024

Untranslated regions (UTRs) contain crucial regulatory elements for RNA stability, translation and localization, so their integrity is indispensable for gene expression. Approximately 3.7% of genetic variants associated with diseases occur in UTRs, yet a comprehensive understanding of UTR variant functions remains limited due to inefficient experimental and computational assessment methods. To systematically evaluate the effects of UTR variants on RNA stability, we established a massively parallel reporter assay on 6555 UTR variants reported in human disease databases. We examined the RNA degradation patterns mediated by the UTR library in two cell lines, and then applied LASSO regression to model the influential regulators of RNA stability. We found that UA dinucleotides and UA-rich motifs are the most prominent destabilizing element. Gain of UA dinucleotide outlined mutant UTRs with reduced stability. Studies on endogenous transcripts indicate that high UA-dinucleotide ratios in UTRs promote RNA degradation. Conversely, elevated GC content and protein binding on UA dinucleotides protect high-UA RNA from degradation. Further analysis reveals polarized roles of UA-dinucleotide-binding proteins in RNA protection and degradation. Furthermore, the UA-dinucleotide ratio of both UTRs is a common characteristic of genes in innate immune response pathways, implying a coordinated stability regulation through UTRs at the transcriptomic level. We also demonstrate that stability-altering UTRs are associated with changes in biobank-based health indices, underscoring the importance of precise UTR regulation for wellness. Our study highlights the importance of RNA stability regulation through UTR primary sequences, paving the way for further exploration of their implications in gene networks and precision medicine.
Multiplexed Assays of Human Disease-relevant Mutations Reveal UTR Dinucleotide Composition as a Major Determinant of RNA Stability
Authors: Su Jia-Ying , Wang Yun-Lin , Hsieh Yu-Tung , Chang Yu-Chi , Yang Cheng-Han , Kang YoonSoon , Huang Yen-Tsung , Lin Chien-Ling
Published: June 2024

UTRs contain crucial regulatory elements for RNA stability, translation and localization, so their integrity is indispensable for gene expression. It has been estimated that ∼3.7% of disease-associated genetic variants are located in UTRs. However, functional interpretation of UTR variants is largely incomplete because efficient means of experimental or computational assessment are lacking. To systematically evaluate the effects of UTR variants on RNA stability, we established a massively parallel reporter assay on 6,555 UTR variants reported in human disease databases. We examined the RNA degradation patterns mediated by the UTR library in multiple cell lines, and then applied LASSO regression to model the influential regulators of RNA stability. We found that TA dinucleotides are the most prominent destabilizing element. Gain of TA dinucleotide outlined mutant UTRs with reduced stability. Studies on endogenous transcripts indicate that high TA-dinucleotide ratios in UTRs promote RNA degradation. Conversely, elevated GC content and protein binding on TA dinucleotides protect high-TA RNA from degradation. Further analysis reveals polarized roles of TA-dinucleotide-binding proteins in RNA protection and degradation. Furthermore, the TA-dinucleotide ratio of both UTRs is a common characteristic of genes in innate immune response pathways, implying that the global transcriptomic regulon involves stability coordination via UTRs. We also demonstrate that stability-altering UTRs are associated with changes in biobank-based health indices, providing evidence that UTR-mediated RNA stability contributes to establishing robust gene networks and potentially enabling disease-associated UTR variants to be classified for precision medicine.
Changes in wing morphology rather than wingbeat kinematics enabled evolutionary miniaturization of hoverflies
Authors: Le Roy Camille , Tervelde Nina , Engels Thomas , Muijres Florian T.
Published: June 2024

Due to physical scaling laws, size greatly affects animal locomotor ability and performance. Whether morphological and kinematic traits always jointly respond to size variation is however poorly known. Here, we examine the relative importance of morphological and kinematic changes in mitigating the consequence of size on aerodynamic force production for weight support in flying insects, focusing on hovering flight of hoverflies (Syrphidae). We compared the flight biomechanics, aerodynamics, and morphology of eight hoverfly species varying from 5 to 100 mg. Our study reveals no effect of body size on wingbeat kinematics among species, suggesting that morphological rather than kinematic changes may compensate for the reduction in weight support associated with an isometric reduction in size. Computational fluid dynamics simulations confirmed that variations in wing morphology, and not kinematics, allow species of different sizes to generate weight support. We specifically show that relatively larger wings and aerodynamically more effective wing shape have evolved in smaller hoverflies, mitigating the reduction in aerodynamic weight support with decreasing size. Altogether, these results suggest that hovering flight of hoverflies underpins highly specialised wingbeat kinematics, which have been conserved throughout evolution; instead, wing morphological adaptations have enabled the evolutionary miniaturisation of hoverflies.
Diurnal rhythmicity in metabolism and salivary effector expression shapes host colonization by aphids
Authors: Han Jinlong , Kunk Daniel , Cui Meihua , Goldstein Yoshiahu , Tzin Vered , Nalam Vamsi J.
Published: June 2024

Diurnal rhythms influence insect behavior, physiology, and metabolism, optimizing their performance by adapting to daily changes in the environment. While their impact on agricultural pests has been briefly explored, our understanding of how these rhythms drive adaptative responses in pest biology and influence host colonization remains elusive. Here, we show that a notorious global aphid pest,
Rhopalosiphum padi
, exhibits distinct diurnal patterns in feeding behavior, with elevated honeydew excretion at night and extended phloem salivation during early nighttime. Temporal aphid transcriptome profiling reveals four diurnally rhythmic clusters, two of which peak at night, exhibiting enrichment in carbohydrate and amino acid metabolism. Beyond the established role in manipulating host responses and allowing sustained feeding, our study reveals the first evidence in any insect species for cyclical fluctuations in salivary effector expression. Silencing key effector genes, peaking in expression during the increased nighttime salivation, results in a more pronounced reduction in aphid feeding activity on host plants during the night compared to the day, a phenomenon not observed on artificial diets. A better understanding of aphid diurnal rhythms and their roles on host colonization provides a promising avenue to refine and optimize pest management, granting a strategic advantage for minimizing crop damage.
Synergizing Bacteriophage Therapy and Computational Neuroscience: A Ray of Hope in the Fight against Antibiotic Resistance
Authors: Ghani Saad , Ghani Imaan , Naureen Shazia
Published: June 2024

Antibiotic resistance presents an urgent and pervasive global health crisis that jeopardises human well-being. This dilemma primarily arises from the inappropriate and excessive use of antibiotics across diverse sectors, leading to the emergence of bacteria that have developed resistance to multiple medications. It is a matter of utmost concern due to its direct link to increased mortality rates and the disconcerting possibility of reverting to an era where antibiotics lose their effectiveness. This student experience paper delves into the potential of bacteriophage therapy as a remedy for antibiotic-resistant infections, a pressing issue emphasized by the National Health Service (NHS) in England. Building upon the recent first-hand experience of the first author while shadowing a General Medical Practitioner in Birmingham, UK, the study delves into critical facets of phage therapy. This exploration encompasses phage selection, formulation, delivery, and safety considerations. It also highlights the convergence with computational neuroscience, emphasizing the pivotal role of computational models in comprehending bacterial infections, antibiotic resistance, and neurological responses. This interdisciplinary approach underscores the necessity for collaborative efforts among microbiologists, healthcare professionals, and computational neuroscientists in addressing global healthcare challenges. Additionally, this experience sheds light on the practice of using antibiotics without a prescription, often for the treatment of infections that do not necessitate antibiotic intervention. This observation underscores the urgent requirement for stricter regulatory controls and an extensive educational program, both at the national and global levels.
Effect of Seed Priming and Fertilizer Levels on Growth, Yield Attributes and Yield of Rabi Maize
Authors: Choudhary Khemendra , Pankhaniya Ramesh M. , Choudhary Mahendra , Pareek Akshay , Choudhary Raghuveer , Gurjar Satyanarayan , Ram Ganesha
Published: June 2024

The present investigation was conducted during the rabi season of 2019-20 at College of Agriculture, Navsari Agricultural University, Navsari to study the “Effect of seed priming and fertilizer levels on rabi maize under south Gujarat condition”. The experiment was laid out in Randomized Block Design with factorial concept (FRBD) with ten treatment combinations consisting of two factors which consists seed priming, Control (No priming), Seed priming with water for 12 hrs., Seed priming with 0.5% KCl for 12 hrs., Seed priming with 0.5% KMnO4 for 12 hrs., Seed priming with 0.5% KH2PO4 for 12 hrs and fertilizer levels, 75% RDF (112.5+45+00, N: P2O5: K2O kg/ha) and 100  Recommended dose of fertilizers (RDF) (150+60+00, N: P2O5: K2O kg/ha). Treatments are replicated three times. The result indicated Seed priming with 0.5% KH2PO4 for 12 hrs recorded significantly higher plant population, number of leaves per plant, plant height, grain and straw yield compared to other treatments. In case of fertilizer levels number of leaves per plant and plant height recorded non significant at 30 DAS. Significantly higher plant height at 60 DAS, 90 DAS, at harvest, grain and straw yield recorded in treatment of 100% RDF (150+60+00, N: P2O5: K2O kg/ha). Treatment combination S5F2: (KH2PO4 at 0.5% for 12 hrs with 100% RDF i.e., 150+60+00, N: P2O5: K2O kg/ha) recorded significantly higher plant height at 90 DAS, at harvest, Grain and straw yield as compared to other treatments. Thus a combination of Seed priming 0.5% KH2PO4 for 12 hrs with 100% RDF (150+60+00, N: P2O5: K2O kg/ha) helps in enhancing the growth parameters, yield attributes and yield of rabi maize without negative influence on plant and the environment.
Evaluating the Efficacy of Selected Insecticides on Diamondback Moth (Plutella xylostella) Damaging Cabbage (Brassica oleracea)
Authors: Aliubaidh Shaik , Tayde Anoorag R. , Chandar Ashok Sakharam , Divya Reguri , Singh Udai Pal
Published: June 2024

A field investigation was carried out in Rabi season of 2022-2023 at the Central Research Farm (CRF), Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, India to evaluate the efficacy of some selected pesticides on controlling diamondback moth that causes yield loss of cabbage. The experiment was laid in Randomized Block Design (RBD) with eight treatments each replicated thrice using a single variety Green Soccer. The treatments viz. NSKE 5% @50 ml/L, Spinosad 45% SC @0.35 ml/L, Emamectin Benzoate 5% SG @0.5 g/L, Neem oil 5% @50 ml/L, Dimethoate 30% EC @1 ml/L, Indoxacarb 14.5% SC @ 0.5 g/L, Cartap Hydrochloride 50% SP @0.5ml/L, and along with an untreated control was used against Plutella xylostella in Cabbage. The overall mean data on larval population of diamond back moth over control on first and second spray revealed that all treatments were significantly superior over control. Among all the treatments Spinosad 45% SC showed the lowest mean larval population (2.04%), (0.93%) followed by Emamectin benzoate 5% SG (2.22%) (1.06%), Indoxacarb 14.5% SC (2.66%) (1.37%), Cartap Hydrochloride 50% SP (3.20%) (1.86%), Dimethoate 30% EC (3.48%) (2.02 %), and NSKE 5% (4.08 %) (2.33 %), Neem oil 5% (3.82 %), (2.37 %) and highest population was recorded in control (8.13%), (7.73%). The highest yield and cost benefit ratio recorded in Spinosad 45% SC (296 q/ha) (1:5.7) followed by Emamectin benzoate 5% SG (264 q/ha) (1:6.2), Indoxacarb 14.5% SC (249 q/ha) (1:5.0), Cartap Hydrochloride 50% SP (215 q/ha) (1:4.8) followed by Dimethoate 30% EC (194 q/ha) (1:4.4), Neem oil 5% (178 q/ha), (1:3.9) and NSKE 5% (170 q/ha) (1:3.8) and control (102 q/ha) (1:2.5). The information obtained in this study has the potential application for controlling diamondback moth and will be useful to the farmers and researchers.
Growth Response and Economics Variability in Hybrid Pigeonpea to Nitrogen and Phosphorus Fertilization
Authors: G. Sai Kumari, , P. Venkata Rao, , M. Sree Rekha, , V Srinivasa Rao,
Published: June 2024

Aims: To study the growth response and economic variability in hybrid pigeonpea to nitrogen and phosphorus fertilization.
Study Design: Factorial randomized block design.
Place and Duration of Study: A field experiment was conducted on deep black cotton soils of Regional Agricultural Research Station, Lam during kharif season, 2018-19 in hybrid pigeonpea (ICPH-2740).
Methodology: The experiment was laid out in factorial randomized block design (FRBD) comprised of four levels of nitrogen in first factor (N1: 20 kg ha-1, N2: 40 kg ha-1, N3: 60 kg ha-1, N4: 80 kg ha-1) and three levels of phosphorus allotted to second factor (P2O5) (P1: 50 kg ha-1, P2: 75 kg ha-1, P3: 100 kg ha-1).
Results: The higher values of grain yield (1900 kg ha-1 & 1833 kg ha-1), net returns (Rs.60522/- & Rs.57181/-) and B:C ratio (1.62 & 1.54) were found with application of nitrogen (60 kg ha-1) and phosphorus (75 kg ha-1), respectively.
Conclusion: It was concluded that in Krishna agro-climatic zone of Andhra Pradesh, an application of 60 kg N ha-1 and 75 kg P2O5 ha-1 was applied for getting economically higher grain yield in hybrid pigeonpea.
Enhancement of ionic conductivity and structural properties by 1‐butyl‐3‐methylimidazolium trifluoromethanesulfonate ionic liquid in poly(vinylidene fluoride–hexafluoropropylene)‐based polymer electrolytes
Authors: Ramesh S. , Lu Soon‐Chien
Published: May 2012

Polymer electrolytes (PEs) with poly(vinylidene fluoride–hexafluoropropylene) [P(VdF–HFP)] as the polymer host and doped with lithium trifluoromethanesulfonate (LiTf) and 1‐butyl‐3‐methylimidazolium trifluoromethanesulfonate (BMIMTf) were synthesized via a solution casting method. This P(VdF–HFP)/LiTf/BMIMTf‐based PE achieved about 1.8 ×10−3 S/cm at room temperature with 100 parts by weight (pbw) of BMIMTf. A discrepancy was observed when 25 pbw of BMIMTf was doped into the system and was related to the reactivity of Li+ and 1‐butyl‐3‐methylimidazolium cation (BMIM+), which could be corroborated with differential scanning calorimetry scans. Fourier transform infrared spectroscopy and X‐ray diffraction revealed the role of P(VdF–HFP) as merely a mechanical support with no direct interaction with BMIMTf. Photoluminescence was also used to detect structural alterations in the local environment of PE. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012
Flammability of EVA/IFR (APP/PER/ZB system) and EVA/IFR/synergist (CaCO3, NG, and EG) composites
Authors: Wu Xinfeng , Wang Lichun , Wu Chao , Wang Genlin , Jiang Pingkai
Published: May 2012

Poly(ethylene‐co‐vinyl acetate)/intumescent flame retardant (ammonium polyphosphate/pentaerythritol/zinc borate system) composites‐EVA/IFR (APP/PER/ZB system) and EVA/IFR/Synergist [CaCO3, natural graphite, or expanded graphite (EG)] composites have been prepared by melting compounding method. The flammability, the combustion process, the quantity of the residual chars, the morphology of the residual chars, and the thermal stability of the chars have been investigated by cone calorimeter, scanning electron microscopy and thermo gravimetric analysis. The results indicate that heat release rate (HRR), total heat released, and total smoke release (TSR) of EVA/IFR (IFR 30 phr) composite decrease to about 67.1, 78.2, and 64% of that of pure EVA, respectively. HRR, THR, and TSR of EVA/IFR/EG (IFR 9 phr, EG 1phr) composite decrease to about 62.1, 76.2, and 44% of that of pure EVA, respectively. The quantity, the thermal stability of residual chars and the char structure are discussed to find the reasons of the phenomenon above. It has been found that the flame retardant of EVA vulcanizates is improved and the fire jeopardizing is dramatically reduced due to the addition of IFR and synergist, which can give some advice to design formulations for practical applications as cable. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Improvement of the properties of plasma‐modified ground tire rubber‐filled cement paste
Authors: Cheng Xiaowei , Chen Haitao , Huang Sheng , Li Zaoyan , Guo Xiaoyang
Published: May 2012

The thesis investigated that the adhesion of ground tire rubber (GTR) to cement can be improved by applying surface plasma modification. The hydrophobic surface of GTR powder has been transformed to a hydrophilic one through plasma treatment. Attenuated total reflectance Fourier transform infrared spectral studies showed the increase in peak intensity at the range of 1400–1600 cm−1, indicating the generation of carbon–carbon double bond after plasma treatment on the surface of the GTR powder. The X‐ray photoelectron spectroscopic analysis further confirmed the presence of oxygen‐containing polar functional groups on the surface of the GTR powder after atmospheric plasma treatment. The improvements in plastic deformation and elastic deformation that attributed to the enhanced interfacial interaction between modified GTR powder and cement matrix were observed for the modified GTR‐filled cement paste via triaxial test. The pore size distribution testing manifested a better compactness of plasma GTR‐filled cement paste. Besides, scanning electron microscope illustrated that adhesion of modified GTR powder with cement matrix increased. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Study of carbon black‐filled poly(butylene succinate)/polylactide blend
Authors: Wang Xuemei , Zhuang Yugang , Dong Lisong
Published: May 2012

In this study, carbon black (CB) was used to control the conductivity and the compatibility of immiscible poly(butylene succinate)/polylactide (PBS/PLA) blend. It is shown that most of the CB particles are selectively dispersed in the matrix PBS phase because of the viscosity ratio of the blend components. The increasing viscosity of PBS phase prevents the coalescence of the dispersed PLA domain during the melt mixing. The domain sizes of PLA are refined when compared with that of blank PBS/PLA blend. The ternary composite shows an onset of the electrical conductivity at low filler loadings (1.5 wt %), which is attributed to a percolation of CB in the insulating matrix polymer. Moreover, the composites exhibited remarkable improvement of rheological properties in the melt state when compared with that of blank PBS/PLA blend. According to the van Gurp‐Palmen plot, the rheological percolation threshold for ternary systems is lower than 1.5 wt %. Furthermore, the ternary composites present improved mechanical properties and thermal stability even at very low loading levels of the CB. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Disecondary amine synthesis and its reaction kinetics with epoxy prepolymers
Authors: Pramanik Monoj , Mendon Sharathkumar K. , Rawlins James W.
Published: May 2012

3,3′‐Diaminodiphenyl sulfone (3,3′‐DDS) was reacted with acetaldehyde in the presence of sodium triacetoxy borohydride via reductive amination to yield a 3,3′‐DDS based secondary diamine, N,N′‐diethyl‐3,3′‐diaminodiphenyl sulfone. Near IR analysis indicated that the 5060 cm−1 peak for primary amine (NH2) in 3,3′‐DDS was absent in the reaction product spectrum. The NH2 proton peak at δ 5.66 ppm shifted to δ 6.16 ppm in the product. Methyl and methylene protons of CH3CH2NHPh group were observed at δ 3.01 and 1.12 ppm, respectively, in the product. The carbon NMR spectrum of the reaction product showed new peaks at δ 37.46 and 14.47 ppm that further confirmed secondary amine formation. The liquid chromatography coupled mass spectra peaks at 248–250 for 3,3′‐DDS and 304 for the reaction product further supported the formation of N,N′‐diethyl‐3,3′‐diaminodiphenyl sulfone. A blend of N,N′‐diethyl‐3,3′‐diaminodiphenyl sulfone with diglycidyl ether of bisphenol‐A (DGEBA) epoxy prepolymer started reacting at about 110–125°C surpassing an energy barrier of ∼ 66 kJ/mol as determined via differential scanning calorimetry analysis. Reaction kinetics were characterized via near IR spectroscopy specific to the reaction between secondary amine and DGEBA epoxy prepolymer. The results confirmed >97% conversion at a cure protocol of 5 h at 80°C, 5 h at 100°C, 11 h at 125°C, and 6 h at 185°C. N,N′‐diethyl‐3,3′‐diaminodiphenyl sulfone‐DGEBA thermoplastics displayed tensile and flexural modulii of 3.08 and 2.86 GPa, respectively, and glass transition temperature (Tg) of 120.77°C. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Preparation and properties of polydimethylsiloxane‐mica composites
Authors: Jia Zhenmei , Chen Shuangjun , Zhang Jun
Published: May 2012

This is a comparison study of the effects of various colloids on polydimethylsiloxane (PDMS) nanocomposites. Mica of layered structure and silica of nanospherical shape were both used with different content. Silane coupling agent was used for surface modification of mica to improve its dispersion. Wide X‐ray diffraction patterns showed no intercalation during the incorporation of mica into PDMS matrix. Rheological characterization of the PDMS composites before curing showed that viscosities of PDMS‐mica composites were much lower than that of PDMS composites with silica, particularly at low shear rates. Scanning electron microscope (SEM) suggested the existence of mica lamellar structure with high aspect ratio within the PDMS matrix. After vulcanization at room temperature, PDMS‐mica composites could obtain mechanical properties close to that of PDMS composites with silica at same filler content. The cooperative effects of mica with silica showed that same mechanical properties of PDMS composites could be obtained at much lower viscosity, cost, and processing insecurity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
A novel water‐soluble, conducting polymer composite for mild steel acid corrosion inhibition
Authors: Ali Fathima Sabirneeza A. , Subhashini S.
Published: May 2012

A novel water‐soluble conducting polymer composite, poly(vinyl alcohol‐histidine) was synthesized from aqueous solution by free radical condensation using persulfate. The composite was characterized using UV–Visible, Fourier transform infrared, scanning electron microscopy, thermogravimetric analysis (TG/DTG), and differential scanning calorimetry techniques while its AC conductance was measured by LCZ analyzer. The inhibitive action of the composite on the corrosion behavior of mild steel in 1MHCl was studied by conventional weight loss method, potentiodynamic polarization studies (Tafel), linear polarization studies, and electrochemical impedance spectroscopy. The effects of inhibitor concentrations, exposure time, and temperature have been investigated. The corrosion rate, inhibition efficiency (IE), and other parameters have been evaluated for different inhibitor concentrations. The composite provided more than 95% IE at an optimum concentration of 0.6% by weight. The results showed the composite as an effective mixed type inhibitor. The adsorption of this inhibitor obeyed Temkin adsorption isotherm. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Preparation and properties of multiwalled carbon nanotube/epoxy‐amine composites
Authors: Jyotishkumar P. , Logakis Emmanuel , George Sajeev Martin , Pionteck Jürgen , Häussler Liane , Haßler Rüdiger , Pissis Polycarpos , Thomas Sabu
Published: May 2012

Different amounts of multiwalled carbon tubes (MWCNTs) were incorporated into an epoxy resin based on diglycidyl ether of bisphenol A and both epoxy precursor and composite were cured with 4,4′‐diamino diphenyl sulfone. Transmission and scanning electron microscopy demonstrated that the carbon nanotubes are dispersed well in the epoxy matrix. Differential scanning calorimetry measurements confirmed the decrease in overall cure by the addition of MWCNTs. A decrease in volume shrinkage of the epoxy matrix caused by the addition of MWCNTs was observed by pressure–volume–temperature measurements. Thermomechanical and dynamic mechanical analysis were performed for the MWCNT/epoxy composites, showing that the Tg was slightly affected, whereas the dimensional stability and stiffness are improved by the addition of MWCNTs. Electrical conductivity measurements of the composite samples showed that an insulator to conductor transition takes place between 0.019 and 0.037 wt % MWCNTs. The addition of MWCNTs induces an increase in both impact strength (18%) and fracture toughness (38%) of the epoxy matrix with very low filler content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Modified shape memory epoxy resin composites by blending activity polyurethane
Authors: Liu Yuyan , Sun He , Tan Huifeng , Du Xingwen
Published: May 2012

A series of modified shape‐memory epoxy resin composites were prepared by blending activity polyurethane (APU). Fourier transform infrared spectroscopy (FTIR), tensile tests, scanning electron microscope (SEM), dynamic mechanical analysis (DMA), and fold‐deploy shape memory tests were used to characterize the structure, mechanical, morphology, thermodynamics, and shape memory performance of these materials. FTIR results suggest that APU has been introduced into the resin matrix resin. Tensile test results show that the addition of appropriate APU can increase the elongation at break significantly, compared with neat epoxy. SEM results indicate that the fracture mechanism has changed from brittle to ductile, suggesting that the brittleness of the material has been overcome. DMA results show that modified materials have lower glass transition temperature (Tg) and lower cross‐linking density for shape memory function. Furthermore, the fold‐deploy shape memory tests prove that the materials possess excellent shape memory properties. They can be deformed into different shapes and recover their original shapes fully within 2 min atTg,while they are hardly affected by ninefold‐deploy cycles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Study on wear and friction behavior of graphite flake‐filled PTFE composites
Authors: Goyal R. K. , Yadav M.
Published: May 2012

The wear rate and coefficient of friction for graphite flake (GF)‐filled polytetrafluoroethylene (PTFE) composites were evaluated on a pin‐on‐disk wear tester under dry conditions. Scanning electron microscopy showed significant reduction in the abrasive wear of the composites. The wear rates of 5 and 10 wt % GF composites were reduced by more than 22 and 245 times, respectively, at sliding speed of 1 m/s. With increasing sliding distance from 1 to 8 km, the wear rate of pure PTFE decreased by 1.4 times whereas that of composites, it decreased up to three times. The significant decreased in wear rate and coefficient of friction might be attributed to the formation of a thin and tenacious transfer film on the counter‐surface. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Properties of nanoparticles filled soft poly(vinyl chloride) composites including antistatic plasticizer
Authors: Liu Shuzhen , Yang Wanqing , Lei Jingxin , Zhou Changlin
Published: May 2012

Nanoparticles (NP) filled permanently antistatic poly(vinyl chloride) (PVC) composites, constituted of dibutyl phthalate (DBP) and antistatic plasticizer (AP) which included bis[2‐(2‐methoxyethoxy)ethyl]phthalate doped with sodium perchlorate (NaClO4), were prepared in a Haaka torque rheometer. Surface resistivity measurement, mechanical test, scanning electron microscopy (SEM) investigation, and thermal gravimetric analysis (TGA)‐differential scanning calorimetry (DSC) analysis were used to investigate the comprehensive properties of PVC/AP/NP (100/40/x) (A40/NP) and PVC/AP/DBP/NP (100/40/40/x) (A80/NP) composites. The results demonstrated that the surface resistivity of A40/NP composites was lower than that of pure A40 composites at a humidity of 60% and 0.1% as the nano SiO2 or TiO2 content is 2 phr, respectively. Moreover, the surface resistivity of A40 composites was decreased by about half an order of magnitude even at the humidity of 0.1% when 2 phr of NP was added. The surface resistivity of A80/NP composites achieved the optimum value as the SiO2 and TiO2 content were 1 phr and 2 phr, respectively. Because the DBP functioned as small molecule plasticizer which endowed PVC composites with comparatively large free volume, the surface resistivity of A80/NP composites is much lower than that of A40/NP composites. The tensile strength and elongation at break of A40/NP (100/2) and A80/NP (100/2) were increased to some extent with respect to pure PVC/AP composites. DSC‐TGA analysis and rheological properties demonstrated that NP filled PVC composites processed good thermostability and thermoprocessability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Production of modified clays and their use in polypropylene‐based nanocomposites
Authors: Seyidoglu Tijen , Yilmazer Ulku
Published: May 2012

The use of modified bentonite as a reinforcement in polypropylene (PP)/organoclay/maleic anhydride grafted polypropylene (MAPP) nanocomposites was investigated. The modified bentonites (organoclays) were prepared from raw (unpurified) bentonite (RB) and two quaternary ammonium salts with long alkyl tails: hexadecyl trimethyl ammonium bromide [HDA][Br] and tetrakisdecyl ammonium bromide [TKA][Br]. The ternary composites were produced by using a corotating twin screw extruder, followed by injection molding, and they exhibited microcomposite structure as observed by XRD. In order to observe the effects of purification of the bentonite, purified bentonite (PB) was obtained through sedimentation of raw bentonite, and later modified with two quaternary ammonium salts: dimethyl dioctadecylammonium chloride [DMDA][Cl] and [TKA][Br], and one quaternary phosphonium salt: tributyl hexadecyl phosphonium bromide [TBHP][Br]. Ternary nanocomposites (PP/organoclay/MAPP) with these organoclays were produced by using a corotating twin screw extruder, followed by batch mixing in an intensive batch mixer, and by injection molding. The use of [DMDA][Cl] and [TBHP][Br] resulted in nanocomposite formation, whereas the use of [TKA][Br] resulted in microcomposite formation as observed by XRD and TEM. Young's modulus of PP was increased by 30% with DMDA and 9% with TBHP. The yield strength of PP was increased by 15% with DMDA and 8.3% with TBHP. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
The effects of polyamic acid on curing behavior, thermal stability, and mechanical properties of epoxy/DDS system
Authors: Yong Liu , Wei Wu , Yu Chen , Pinpin Shi , Mingchang Liu , Xiang Wu
Published: May 2012

A thermoplastic modification method was studied for the purpose of improving the toughness and heat resistance and decreasing the curing temperature of the cured epoxy/4, 4′‐diaminodiphenyl sulfone resin system. A polyimide precursor‐polyamic acid (PAA) was used as the modifier which can react with epoxy. The effects of PAA on curing temperature, thermal stability and mechanical properties were investigated. The initial curing temperature (Ti) of the resin with 5 wt % PAA decreased about 50°C. The onset temperature of thermal decomposition and 10 wt %‐weight‐loss temperature for the resin system containing 2 wt % PAA increased about 60°C and 15°C respectively. Besides, the value of impact toughness and plain strain fracture toughness for the modified epoxy resin increased ∼ 190% and 55%, respectively. Those changes were attributed to the outstanding thermal and mechanical properties of polyimide, and more importantly to formation of semi‐interpenetrating polymer networks composed by the epoxy network and linear PAA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Novel fabrication of disorderly exfoliated sodium montmorillonite in a styrene–butadiene rubber matrix
Authors: Wang Qingguo , Zhong Yuan , Zhang Xiaohong , Song Zhihai
Published: May 2012

Using industrial technologies, we prepared a sodium montmorillonite (Na‐MMT) slurry and an irradiated styrene–butadiene rubber (SBR) latex, and then spray dried them to produce a novel, ultrafine fully vulcanized powder SBR (UFPSBR)/Na‐MMT nanocompound powder in which the nanoscale UFPSBR particles and exfoliated Na‐MMT were isolated and stuck together. When the UFPSBR/Na‐MMT nanocompound powder was mixed with crude SBR, the exfoliated Na‐MMT was disorderly dispersed in the SBR matrix because of the carrier nature of the UFPSBR particle, which is compatible with SBR and disperses easily in the SBR matrix, and the SBR/UFPSBR/Na‐MMT ternary nanocomposite was prepared. When compared with SBR/Na‐MMT binary composites, the SBR/UFPSBR/Na‐MMT ternary nanocomposite has a shorter vulcanization time, higher strength, and better flame retardancy because of the good dispersion of exfoliated Na‐MMT in the SBR matrix with a Na‐MMT loading range of 4 phr. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2013
Biocompatibility evaluation of glycolide‐containing polyesters in contact with osteoblasts and fibroblasts
Authors: Scislowska‐Czarnecka Anna , Pamula Elzbieta , Kolaczkowska Elzbieta
Published: May 2012

Biodegradable aliphatic polyesters have numerous biomedical applications and their capacity to degrade in biological fluids provides the significant advantage of their removal. Three glycolide‐containing aliphatic polyesters: a copolymer of glycolide and L‐lactide (PGLA), a terpolymer of glycolide, L‐lactide and ε‐caprolactone (PGLCap) and a copolymer of glycolide, and ε‐caprolactone (PGCap) were tested to evaluate their biocompatibility towards osteoblasts and fibroblasts. Each of the polymer units was previously reported to have acceptable biological properties and good biodegradability, and PGLA is already used for biomedical applications. Here we report that both PGLCap and PGCap affected cell adherence, and compromised cell viability as estimated by flow cytometric analyses of apoptotic and necrotic cells. The two polymers enhanced also production of numerous inflammation‐related factors: nitric oxide, matrix metalloproteinases (MMP‐2 and MMP‐9), and cytokines, including pro‐inflammatory TNF‐α, IL‐1β, IL‐6, and chemokines (IL‐8 or MCP‐1) attracting leukocytes. The effects of PGLCap and PGCap were similar despite the fact that they possess different characteristics: amorphous/smooth surface and semicristalline/rough surface, respectively. However, their common feature, distinctive from PGLA, is a presence of ε‐caprolactone units in their structure. This compound is considered to be acceptably biocompatible but our data suggest that its copolymerization with glycolide and L‐lactide does not provide satisfactory biocompatibility towards osteoblasts and fibroblasts. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Thermoresponsive sodium alginate‐g‐poly(N‐isopropylacrylamide) copolymers III. Solution properties
Authors: Cheaburu Catalina Natalia , Ciocoiu Oana‐Nicoleta , Staikos Georgios , Vasile Cornelia
Published: May 2012

Stimuli‐responsive biocompatible and biodegradable materials can be obtained by combining polysaccharides with polymers exhibiting lower critical solution temperature (LCST) phase behavior, such as poly(N‐isopropylacrylamide) (PNIPAAm). The behavior of aqueous solutions of sodium alginate (NaAl) grafted with PNIPAAm (NaAl‐g‐PNIPAAm) copolymers as a function of composition and temperature is presented. The products obtained exhibit a remarkable thermothickening behavior in aqueous solutions if the degree of grafting, the concentration, and the temperature are higher than some critical values. The sol–gel‐phase transition temperatures have been determined. It was found that at temperatures below LCST the systems behave like a solution, whereas at temperatures above LCST, the solutions behave like a stiff gel, because of PNIPAAm segregation. This behavior is reversible and could find applications in tissue engineering and drug delivery systems. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Phenomenological‐based kinetics modelling of dehydrogenation of ethylbenzene to styrene over a Mg3Fe0.25Mn0.25Al0.5 hydrotalcite catalyst
Authors: Hossain Mohammad M. , Atanda Luqman , Al‐Khattaf Sulaiman
Published: May 2012

This communication reports a mechanism‐based kinetics modelling for the dehydrogenation of ethylbenzene to styrene (ST) using Mg3Fe0.25Mn0.25Al0.5 catalyst. Physicochemical characterisation of the catalyst indicates that the presence of basic sites Mg2+O2− on the catalysts along with Fe3+ is responsible for the catalytic activity. The kinetics experiments are developed using a CREC Fluidised Riser Simulator. Based on the experimental observations and the possible mechanism of the various elementary steps, Langmuir–Hinshelwood type kinetics model are developed. To take into account of the possible catalyst deactivation a reactant conversion‐based deactivation function is also introduced into the model. Parameters are estimated by fitting of the experimental data implemented in MATLAB. Results show that one site type Langmuir–Hinshelwood model appropriately describes the experimental data, with adequate statistical fitting indicators and also satisfied the thermodynamic restraints. The estimated heat of adsorptions of EB (64 kJ/mole) is comparable to the values available in the literature. The activation energy for the formation of ST (85.5 kJ/mole) found to be significantly lower than that of the cracking product benzene (136.6 kJ/mole). These results are highly desirable in order to achieve high selectivity of the desired product ST. © 2012 Canadian Society for Chemical Engineering
Accumulation of weathered p,p′-DDTs in hybridized Cucurbita pepo cultivars
Authors: Isleyen Mehmet , Sevim Pinar , White Jason C.
Published: May 2012

Cucurbita pepo spp pepo (zucchini) is known as an exceptional weathered dichlorodiphenyldichloroethylene (DDE) accumulator, whereas Cucurbita pepo ssp ovifera (squash) is termed a nonaccumulator. Experiments were conducted with hybridized zucchini and squash to assess the inheritance pattern of DDX (the sum of p,p′-dichlorodiphenyltrichloroethane [p,p′-DDT], p,p′-dichlorodiphenyldichloroethane [p,p′-DDD], and p,p′-dichlorodiphenyldichloroethylene [p,p′-DDE]) accumulation potential in xylem sap and tissues of parental, F1 hybrids, and F1 backcross (BC) generations of plants. Plants were grown in pots containing soil with weathered DDX at 732 to 1,130 ng/g soil or under field conditions in soil with 322 to 2,700 ng/g. The DDX stem bioconcentration factors and xylem sap values showed differences between parental and hybridized plants of squash and zucchini. For squash grown in greenhouse conditions, the DDX flow rate in the xylem sap was 17.3, 121, and 40.8 ng/h in parental, F1 hybrids, and F1 BC plants, respectively. Similarly, the stem DDX content of parental, F1, and F1 BC squash was 11, 253, and 96 ng/g (dry wt), respectively. A similar inheritance pattern for squash was observed when the plants were grown under field conditions. The DDX flow rates in the xylem sap of pot-grown parental, F1, and F1 BC zucchini cultivars were 100, 8.5, and 26 ng/hr, respectively, and the stem DDX content was 191, 102, and 142 ng/g, respectively. Again, similar trends in accumulation potential were observed for hybridized zucchini grown under field conditions. The DDX concentrations in parental plants matched the expected pattern, with hybrids midway between the two species, and the backcross being more like the parent again for both species. This inheritance pattern of contaminant accumulation and translocation ability follows classical Mendelian segregation and suggests single-gene or single-locus control. Environ. Toxicol. Chem. 2012; 31: 1699–1704. © 2012 SETAC
Toxicity of carbon nanotubes to freshwater aquatic invertebrates
Authors: Mwangi Joseph N. , Wang Ning , Ingersoll Christopher G. , Hardesty Doug K. , Brunson Eric L. , Li Hao , Deng Baolin
Published: May 2012

Carbon nanotubes (CNTs) are hydrophobic in nature and thus tend to accumulate in sediments if released into aquatic environments. As part of our overall effort to examine the toxicity of carbon-based nanomaterials to sediment-dwelling invertebrates, we have evaluated the toxicity of different types of CNTs in 14-d water-only exposures to an amphipod (Hyalella azteca), a midge (Chironomus dilutus), an oligochaete (Lumbriculus variegatus), and a mussel (Villosa iris) in advance of conducting whole-sediment toxicity tests with CNTs. The results of these toxicity tests conducted with CNTs added to water showed that 1.00 g/L (dry wt) of commercial sources of CNTs significantly reduced the survival or growth of the invertebrates. Toxicity was influenced by the type and source of the CNTs, by whether the materials were precleaned by acid, by whether sonication was used to disperse the materials, and by species of the test organisms. Light and electron microscope imaging of the surviving test organisms showed the presence of CNTs in the gut as well as on the outer surface of the test organisms, although no evidence was observed to show penetration of CNTs through cell membranes. The present study demonstrated that both the metals solubilized from CNTs such as nickel and the “metal-free” CNTs contributed to the toxicity. Environ. Toxicol. Chem. 2012; 31: 1823–1830. © 2012 SETAC
Learning‐dependent plasticity in human auditory cortex during appetitive operant conditioning
Authors: Puschmann Sebastian , Brechmann André , Thiel Christiane M.
Published: May 2012

Animal experiments provide evidence that learning to associate an auditory stimulus with a reward causes representational changes in auditory cortex. However, most studies did not investigate the temporal formation of learning‐dependent plasticity during the task but rather compared auditory cortex receptive fields before and after conditioning. We here present a functional magnetic resonance imaging study on learning‐related plasticity in the human auditory cortex during operant appetitive conditioning. Participants had to learn to associate a specific category of frequency‐modulated tones with a reward. Only participants who learned this association developed learning‐dependent plasticity in left auditory cortex over the course of the experiment. No differential responses to reward predicting and nonreward predicting tones were found in auditory cortex in nonlearners. In addition, learners showed similar learning‐induced differential responses to reward‐predicting and nonreward‐predicting tones in the ventral tegmental area and the nucleus accumbens, two core regions of the dopaminergic neurotransmitter system. This may indicate a dopaminergic influence on the formation of learning‐dependent plasticity in auditory cortex, as it has been suggested by previous animal studies. Hum Brain Mapp 34:2841–2851, 2013. © 2012 Wiley Periodicals, Inc.
The five factors of personality and regional cortical variability in the baltimore longitudinal study of aging
Authors: Kapogiannis Dimitrios , Sutin Angelina , Davatzikos Christos , Costa Paul , Resnick Susan
Published: May 2012

Although personality changes have been associated with brain lesions and atrophy caused by neurodegenerative diseases and aging, neuroanatomical correlates of personality in healthy individuals and their stability over time have received relatively little investigation. In this study, we explored regional gray matter (GM) volumetric associations of the five‐factor model of personality. Eighty‐seven healthy older adults took the NEO Personality Inventory and had brain MRI at two time points 2 years apart. We performed GM segmentation followed by regional analysis of volumes examined in normalized space map creation and voxel based morphometry‐type statistical inference in SPM8. We created a regression model including all five factors and important covariates. Next, a conjunction analysis identified associations between personality scores and GM volumes that were replicable across time, also using cluster‐level Family‐Wise‐Error correction. Larger right orbitofrontal and dorsolateral prefrontal cortices and rolandic operculum were associated with lower Neuroticism; larger left temporal, dorsolateral prefrontal, and anterior cingulate cortices with higher Extraversion; larger right frontopolar and smaller orbitofrontal and insular cortices with higher Openness; larger right orbitofrontal cortex with higher Agreeableness; larger dorsolateral prefrontal and smaller frontopolar cortices with higher Conscientiousness. In summary, distinct personality traits were associated with stable individual differences in GM volumes. As expected for higher‐order traits, regions performing a large number of cognitive and affective functions were implicated. Our findings highlight personality‐related variation that may be related to individual differences in brain structure that merit additional attention in neuroimaging research. Hum Brain Mapp 34:2829–2840, 2013. © 2012 Wiley Periodicals, Inc.