bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and Property Testing of Compatibilized Poly(l‐lactide)/Thermoplastic Polyurethane Blends
Authors: Suthapakti Kanyarat , Molloy Robert , Punyodom Winita , Nalampang Kanarat , Leejarkpai Thanawadee , Topham Paul D. , Tighe Brian J.
Published: August 2015

Poly(l‐lactide) (PLL) has been blended with a polycaprolactone‐based thermoplastic polyurethane (TPU) elastomer as a toughening agent and a poly(l‐lactide‐co‐caprolactone) (PLLCL) copolymer as a compatibilizer. Both 2‐component (PLL/TPU) and 3‐component (PLL/TPU/PLLCL) blends were prepared by melt mixing, characterized, hot‐pressed into thin sheets and their tensile properties tested. The results showed that, although the TPU could toughen the PLL, the blends were largely immiscible leading to phase separation. However, addition of the PLLCL copolymer improved blend compatibility. The best all‐round properties were found for the 3‐component blend of composition PLL/TPU/PLLCL = 90/10/10 parts by weight.
The Potential of Perlite as an Odour‐Adsorbing Fillers in Natural Rubber Vulcanizates
Authors: Rattanaplome Tithinun , Pornprasit Philaiwan , Chantaramee Napat
Published: August 2015

The objective of this research was to reduce an offensive odour by using perlite as an odour‐adsorbing filler. Perlite was mixed with highly odorous STR20 and RSS5. Perlite content was varied at 0, 10, 20 and 30 phr. The ability to reduce odour by sensory method and GC‐MS were examined. Cure characteristics and mechanical properties, such as tensile strength, hardness and abrasion resistance, were also determined. From the sensory method, the odour reduction efficiency increased with increasing perlite content.With an addition of perlite, the reduction of some components from an offensive odour, such as thiourea and benzothiazole, was also observed using GC‐MS technique. Furthermore, the addition of perlite showed an increase in torque difference, a slight change in scorch time and a decrease in cure time, an increase in hardness and abrasion resistance but a decrease in tensile strength. Perlite was shown to be comparable to clay with respect to mechanical properties and potentially be used as low‐cost and odour‐adsorbing filler.
Crystallization of Double Crystalline Diblock Copolymer by Dynamic Monte Carlo Simulation
Authors: Kundu Chitrita , Dasmahapatra Ashok Kumar
Published: August 2015

We report dynamic Monte Carlo simulation results on the crystallization of double crystalline A‐B diblock copolymer, wherein the melting temperature of A‐block is higher than B‐block. Crystallization of A‐block precedes the crystallization of B‐block upon cooling from a homogeneous melt. The interaction between A‐type and B‐type units is modelled as the repulsive interaction to represent their mutual immiscibility. The morphological development is controlled by the interplay between crystallization and microphase separation. With increasing segregation strength, we observe a gradual decrease in crystallinity accompanying with smaller and thinner crystals. During crystallization, A‐block crystallizes first and creates confinement for the crystallization of the B‐block. Thus, crystallization of B‐block slows down, influencing the overall crystal morphology. With changing block composition, we observe a non‐monotonic trend in the crystallization behaviour (viz., crystallinity, lamellar thickness) of A‐block when B‐block composition is significantly higher than A‐block. This non‐monotonic trend is attributed to the dilution effect of the B‐block.
Effect of Vegetable Oils as Processing Aids in SBR Compounds
Authors: Pechurai Worawan , Chiangta Warunee , Tharuen Pariya
Published: August 2015

This research was studied on the cure characteristics and mechanical properties of rubber compounds using vegetable oil as the processing aid in styrene butadiene rubber compound such as castor oil and jatropha oil in comparison with petroleum based aromatic oil. The quantities of the oils varied from 0 to 9 phr. The study showed that the cure characteristics in terms of maximum torque and torque difference tended to decrease with increasing concentrations of oils, while scorch time and cure rate index increased. Moreover, hardness and 100% modulus tended to decrease as increasing loading levels of the oils in the SBR vulcanizates while elongation at break increased. However, tensile strength was not significantly affected. For using the vegetable oils, we found that abrasion resistance and rebound resilience were better than those of aromatic oil, and also displayed high hardness. It could be concluded that the vegetable oils were better alternative processing aids compared to aromatic oil, which has been reported as carcinogenic.
Biopolymer‐Nanocomposites with Silica, Alumino‐Silicate and Graphene: Structural Characterization and Properties
Authors: Mittal Vikas , Patwary F. , Chaudhry Ali U. , Luckachan Gisha E.
Published: August 2015

Mechanical, rheological and thermal properties of melt processes bio‐nanocomposites of poly(butylene succinate) (PBS) and chitosan blends with 0‐dimensional and 2‐dimensional nanofillers were studied. The weight ratio of PBS and chitosan in the blend was optimized based on ease of processing, mixing quality and mechanical performance. The chitosan phase was observed to be dispersed as non‐continuous phase in PBS and enhanced it mechanical properties markedly. The fillers had different degrees of improvement in the mechanical performance with graphene exhibiting a maximum increase of > 225% in the Young's modulus at 10% filler content. The IR characterization also signaled toward chemical interactions between the polymer and graphene phases. Increasing the filler content had overall reduction in crystallinity.
Potential Antibacterial Activity of Polystyrene Nanoparticles/Chitosan Coated on Cotton Fabrics
Authors: Siralertmukul Krisana , Watcharamul Supawin , Wicheanpaisan Natthakrita , Nuisin Roongkan
Published: August 2015

This research is to study the potential of using polystyrene nanoparticles and chitosan solution to increase the anti‐bacterial activity on cotton fabrics prepared by a conventional pad‐dry‐cure method. Firstly, cotton fabrics were coated with chitosan solutions at the concentrations of 0.1, 0.5, and 1.0 (%w/v) and tested for the antibacterial property which was determined by clear zone measurement and viable count assay using Escherichia coli (ATCC 25922) as a tested microorganism. The results showed that, the percentage bacterial reductions were 87.2, 86.3, and 48.5%, respectively, when the cotton fabrics was coated only with chitosan solution. When polystyrene nanoparticle solution was coated onto cotton fabrics prior to coating with chitosan solutions at the concentrations of 0.1, 0.5, and 1.0 (%w/v), the percentage bacterial reductions were 90.3, 90.8, and 65.5%, respectively. This indicated that coating the cotton fabrics with polystyrene nanoparticles prior to chitosan coating would remarkably increase the antibacterial activity. The scanning electron micrographs showed that polystyrene nanoparticles were aggregated and inserted in between the interfiber spacings. The thin film of chitosan was also observed on the surface of cotton fabrics and hydrophobic property of the fabrics was tested via contact angle measurement.
Biopolymer Films Based on Chitosan and Polyethylene Glycol with Pineapple Leaf Fiber for Food Packaging Applications
Authors: Ninjiaranai Padarat
Published: August 2015

Pineapple is a tropical plant native to South East Asia. Pineapple leaf fiber is rich in cellulose, relatively inexpensive and abundantly available. Furthermore, it has the potential for polymer reinforcement, and is more environmentally friendly than films that are reinforced with the artificial additives. The objectives of the present work were to compare the mechanical and water vapor barrier properties of biopolymer films, chitosan and polyethylene glycol 6000 (PEG 6000), with and without incorporating pineapple leaf fibers which had been chemically treated in an alkaline solution. The water vapor permeability (WVP), % soluble matter (SM), moisture index, tensile strength (TS) and % elongation (E) were investigated in these films. The composite yellow film exhibited an excellent water vapor permeability of 5.14 ± 1.87 g mm m−2day−1kPa−1. The solubility was 65.00 ± 0.97% while the moisture index was in the range of 10.50‐31.20%. The results suggested that biodegradable films could be advantageously used to replace polymer films in the packaging of freshly processed vegetables and thereby reduce the negative environmental impact of polymeric films.
A New Crosslinker for the Preparation of Silk Fibroin Hydrogels
Authors: Suttenun Nuchada , Punyamoonwongsa Patchara
Published: August 2015

Silk fibroin (SF) hydrogels has recently been explored as promising matrices for biomedical applications due to their excellent biodegradability, biocompatibility and hydrophilicity. Despite these, native SF hydrogels showed poor water resistance with typical uncontrollable gelation kinetics. To overcome these drawbacks, a new method of chemical crosslinking using O'O‐bis[2‐(N‐succinimidyl succinylamino) ethyl]polyethylene glycol (NHSP) as a homobifunctional protein crosslinker was employed. A crosslinking reaction, performed under physiological conditions, was completed within 24 hours, producing a hybrid interconnected porous architecture. This network formation contributed to the shortened gelation kinetics and was confirmed by the appearance of a new IR absorption peak of the ether linkage (1102–1104 cm−1). A new thermal degradation temperature found at 430 °C also reconfirmed the presence of such newly‐formed covalent network within the samples. In addition, NHSP could induce a silk phase transformation from the α‐helices into the β‐sheets, as convinced by the shifts of the amide absorption bands (Amide I, Amide II and Amide III), illustrating their strong intermolecular interactions. The new proposed method has thus, proven its potential use to render the silk‐based materials for controlled drug delivery applications.
Properties of Dual Cured Polyurethane Film Coatings Based on Natural Rubber
Authors: Thitithammawong Anoma , Rungvichaniwat Adisai , Srangkum Suthasinee
Published: August 2015

Dual curable polyurethane (PU) material coating was prepared from natural rubber based polyol. The end capping technique was applied to terminate the PU prepolymer chains with thiol and acrylate monomers. The end capped PU coatings had improved physical and mechanical properties as well as curing time. The developed end capped PU prepolymers or PUDUALs obviously reduced paint defects. A 2/1 molar ratio of thiol/acrylate monomers prominently gave a PUDUAL coating with properties comparable to a commercial PU coating.
Study on Reuse of Diphenyl Disulfide‐Devulcanized Natural Rubber from Truck Tires
Authors: Saiwari Sitisaiyidah , Waesateh Kamaruddin , Lopattananon Natinee , Thititammawong Anoma , Kaesaman Azizon
Published: August 2015

The post‐consumer rubber in truck tires can be converted to a valuable raw material by de‐vulcanization. Natural rubber (NR) from used truck tires (UR) has been recycled by thermo‐chemical de‐vulcanization using DPDS as a de‐vulcanization aid. The de‐vulcanization efficiency is analyzed in term of the soluble fraction and the crosslink density of de‐vulcanizates (D‐UR). The D‐UR has significantly higher soluble fraction and lower crosslink density compared to those of original UR, indicating destruction of the rubber network by the de‐vulcanization. Blends of the D‐UR with virgin NR were also prepared at various blend ratios. D‐UR loading can be up to 40% with acceptable mechanical properties. The curing system and the compounding recipes for the blends were studied to achieve material properties having closely comparable to those achieved with virgin raw materials.
Enhancement of Mechanical Properties of Photo‐Responsive Polymers
Authors: Christogianni Paraskevi , Moniruzzaman Mohammed , Kister Guillaume
Published: August 2015

Photomechanical polymers are characterised by changes in their mechanical properties under light radiation. This process is driven by the reversible isomerisation of chromophores in a polymer matrix. Azobenzene‐based materials can switch their isomeric structure from trans to cis by light of appropriate wavelength. When this class of materials is chemically connected to polymers as a side chain or backbone, the polymers show photo‐induced mechanical property improvements. This paper reports on the photomechanical property changes in a series of copolymers of methyl methacrylate (MMA) and methacryloyloxy azobenzene (MOAB) with azobenzene in the side chains. The chromophore loading ranges between 10% and 65%mol. Nanoindentation was employed to quantify the relationship between the variation in the photo‐driven mechanical properties and the amount of chromophore loading in the copolymer films. Results demonstrated that the stiffness of the polymer films increases up to 19% with an optimum loading of 30%mol azobezene. Above this level of azobenzene loading (30%mol) the stiffness decreases suggesting a maximum effect can be obtained with 30%mol loading in this copolymer matrix. The rate of isomerisation in thin films was established by monitoring the visible spectra before and after irradiation. The duration of trans to cis isomerisation increases with azobenzene loading. The cis to trans isomerisation under visible light is faster than the trans to cis conversion, due to the greater thermodynamic stability of the trans form.
DFT Study of Proton Transfer in Methyl Urocanate and Butyl Urocanate
Authors: Yana Janchai , Chirachanchai Suwabun , Jarumaneeroj Chatchai , Lee Vannajan Sanghiran , Kodchakorn Kanchanok , Tashiro Kohji , Nimmanpipug Piyarat
Published: August 2015

Development of proton conductivity is necessary to improve polymer electrolyte efficiency of proton exchange membrane fuel cell (PEMFC) which is alternative environmentally friendly resource. Modification of polymer electrolyte has been employed using water free polymer instead of hydrated polymer membrane to disregard water loss problem at high temperature. Heterocycles such as imidazole and benzimidazole derivatives was considered for anhydrous membrane modification to encourage proton transfer in polymer electrolyte membrane. Alkyl urocanate was interested as a vehicle for proton transfer between side chains of polymer membrane. In this work, investigation of blending of butyl urocanate in polymer membrane to assist the proton transfer ability was carried out. Energy barrier of proton movement between alkyl urocanate was calculated. The preferred orientation of bimolecular alkyl urocanaetes was initiated by crystallographic data. The energies of various proton position in between neighbouring molecules were calculated to determine the barrier of proton transfer. The density function theory (DFT) with generalized gradient approximation (GGA) and BLYP function was used for calculation. The energy barrier of butyl urocanate was found lower than methyl urocanate corresponding to the previous experimental proton conductivity data.
Cellulose Graft Poly(acrylic acid) and Polyacrylamide: Grafting Efficiency and Heavy Metal Adsorption Performance
Authors: Wichaita Waraporn , Samart Chanatip , Yoosuk Boonyawan , Kongparakul Suwadee
Published: August 2015

Corn cob cellulose was prepared by alkali‐treatment method and grafted with acrylic acid and acrylamide using ammonium persulphate as an initiator and N,N'‐methylenebisacrylamide as a cross‐linker. The influences of monomer to cellulose ratio, initiator content, cross‐linker content and reaction temperature on grafting efficiency were studied. The maximum grafting efficiency was achieved at 89% at the appropriate condition. Properties of grafted cellulose were characterized by SEM, FTIR, CHNO analysis and TGA. Poly(acrylic acid) and polyacrylamide modified cellulose were used as adsorbents for Cu(II) and Ni(II) removal from aqueous solution. The adsorption capacity was in the range of 8–12 mg g−1 with the removal performance up to 52–99%.
Reusable Modified Natural Rubber Foam for Petroleum‐Based Liquid Removal
Authors: Ratcha Arissara , Samart Chanatip , Yoosuk Boonyawan , Kongparakul Suwadee
Published: August 2015

A new kind of natural rubber‐based oil sorbent material was prepared by sulfur vulcanization system. Natural rubber (NR) foam was modified with poly(butyl methacrylate) (PBMA) and poly(butyl acrylate) (PBA) which were prepared by emulsion polymerization. The functionality of pure polyacrylate and modified NR foam were characterized by Fourier transform infrared (FTIR) spectroscopy. Morphology of the modified NR foam was observed by scanning electron microscope (SEM). The oil/water sorption capacity and reusability of modified NR foam were investigated. Sorption test of modified NR foam showed that the modified NR foam were efficiently removed petroleum‐based liquid (viscosities of 0.49–37 cSt) such as gasohol, diesel, engine oil, xylene and toluene. The oil sorption capacity of modified NR foam was in the range of 5–16 g g−1 and maintained oil sorption capacity over the range of 3–15 g g−1 after 20 cycles of absorption. About 95% of foam can be recovered by squeezing or evaporating the oil or organic solvent within the modified NR foam. The results showed that the modified NR foams are promised as reusable oil sorbent.
High Temperature Thermal Gradient Interaction Chromatography (HT‐TGIC) for Blends of Ethylene/1‐Octene Copolymers: A Mathematical Model
Authors: Inwong Nantiya , Anantawaraskul Siripon , Soares João B. P. , Al‐Khazaal Abdulaal Z.
Published: August 2015

High temperature thermal gradient interaction chromatography (HT‐TGIC) was recently developed to characterize chemical composition distribution (CCD) of ethylene/1‐olefin copolymers based on the interaction between polymer chains and graphitic surface. In this work, a mathematical model of HT‐TGIC was developed based on the population balance in a non‐equilibrium, multi‐stage adsorption/desorption process. Results from the proposed model were found to be in a good agreement with the experimental results of blends over various operating conditions.
Preparation of Green High Impact Polystyrene Beads via Suspension Polymerization
Authors: Kittiwattanakul Tatiya , Prasassarakich Pattarapan , Hinchiranan Napida
Published: August 2015

The aim of this research was to investigate the important effects and their interaction on production of Green High Impact Polystyrene (HIPS) synthesized by using natural rubber (NR) as elastomeric phase via suspension polymerization initiated and stabilized by using benzoyl peroxide (BPO) and poly(vinyl alcohol) (PVA), respectively. The effects of reaction parameters: wt ratio of NR/styrene and PVA/NR including agitation rate on HIPS bead size were studied by using 2k factorial design experiment. The HIPS bead size increased with increasing the NR content (0.01–0.08 w/w of NR/ST) in the mixture of NR/styrene syrup. Whereas, the increase in the PVA content (1.5–2.5 w/w of PVA/NR) and agitation rate (350–450 rpm) decreased HIPS bead size. Thermal gravimetric analysis (TGA) results were showed that HIPS containing the various amounts of NR had more thermal stability than the neat PS. Moreover, the glass transition temperature (Tg) of PS phase in the obtained HIPS bead was shifted from 97.9 to 84.2 °C when the wt ratio of NR/ST was increased to 0.08.
Studies of Different Properties of Polystyrene‐Asphaltene Composites
Authors: Siddiqui Mohammad Nahid
Published: August 2015

The study of thermal and viscoelastic properties of polystyrene composites with different filler loadings of asphaltenes were carried out. The thermogravimetric analysis revealed that the T10 for neat polystyrene was around 365°C and it increased to 440°C with an addition of asphaltene (3 wt% loading, St3). Further addition of asphaltene also showed an increase in the T10 value compared to the neat polystyrene. The second important parameter from TGA analysis can be seen that the neat polystyrene had a degradation maximum (T50) at around 432°C and St3 composite shows the highest T50 value of 450°C. Differential Scanning calorimetric studies of the composites shows that Tg of polystyrene was around 66°C and St2 composite showed the Tg at the maximum of 69°C, which infers that there was interaction between the filler and the matrix. St3 composite shows higher storage modulus as compared to all others. Addition of asphaltenes improved the storage modulus of polystyrene system due to the compatibility effect, which facilitated better load transfer due to the strengthening of the interphase between the filler and matrix. Loss modulus curves of the polystyrene and composites showed a higher loss modulus than the neat polymer in the whole temperature region. It was concluded that the thermal stability and viscoelastic properties of the polystyrene composites were significantly improved with the addition of asphaltene as filler.
Effect of a combined oral contraceptive on patency of arterial anastomosis in a female rat model
Authors: Dadaci Mehmet , Oztekin Can , Oztekin Pelin Seher , Sargon Mustafa Fevzi , Ozgur Figen
Published: August 2015

Background

Oral contraceptives, which may lead to thrombotic events, are widely used drugs by women in reproductive age, some of whom might need emergent or elective microsurgical intervention. This study was planned to investigate the effects of combined oral contraceptives (COC) on arterial anastomosis patency in female rat model.

Methods

A third generation COC (ethinyl estradiol and desogestrel) was used in this study. A total of 50 female Wistar albino rats were included. The rats were divided into two groups. Experimental group received 0.03 mg ethinyl estradiol/0.15 mg desogestrel with gastric catheter for 20 days before the surgery. Afterward, the femoral arteries of all rats were divided and anastomosed. The patency of the anastomoses were assessed surgically (at 15 min, 7th day) and radiologically with Doppler ultrasonography (at 3rd and 7th days). The samples were examined using light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Results

The early patency assessed in the 15th min showed arterial flow in all rats. But at the 7th day 68% of the anastomosis were patent in the COC group while 100% of the anastomosis were patent in the control group as demonstrated surgically and radiologically (P = 0.004). Microscopic examination showed an increase in cytoplasmic organelles and activation of endothelial cells in all rats in the experimental group that received COCs.

Conclusion

The present study demonstrated the negative effects of the use of COCs on anastomosis patency in rats. © 2015 Wiley Periodicals, Inc. Microsurgery 35:553–559, 2015.
Electromagnetic eigenfields in checkerboard patterns
Authors: Kjellmert B.
Published: August 2015

Here are described four solvers for time‐harmonic electromagnetic fields in checkerboard patterns. A pattern is built by four squares with constant permittivity, or . It is enclosed by conducting walls or is a unit cell of a periodic structure. The field is represented in two ways: by , the transverse component of the magnetic induction, and by , the magnetic vector potential in Lorenz gauge. and satisfy Helmholtz equations in each square as well as transmission and boundary conditions (BCs). These governing equations yield eigensolutions and , which are found to be at worst. Variational versions of the governing equations are introduced. The weak formulations for are standard, while those for are new. They imply that the derivative transmission and BCs are satisfied weakly on interfaces between regions with different permittivity. Eigenpairs are computed approximately by spectral element methods. They yield mutually consistent eigenpairs. However, only about half of the eigenpairs () correspond to eigenpairs (). For each set of BCs, the first few eigenfrequencies are given by tables, and some of the eigenfunctions are presented by contour plots. © 2015 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 32: 418–444, 2016
Targeting Glycoprotein NMB With Antibody‐Drug Conjugate, Glembatumumab Vedotin, for the Treatment of Osteosarcoma
Authors: Roth Michael , Barris David M. , Piperdi Sajida , Kuo Vicky , Everts Stephanie , Geller David , Houghton Peter , Kolb E. Anders , Hawthorne Thomas , Gill Jonathan , Gorlick Richard
Published: August 2015

Background

Cure rates for children and young adults with osteosarcoma have remained stagnant over the past three decades. Targeting glycoprotein non‐metastatic b (GPNMB) with the antibody‐drug conjugate glembatumumab vedotin has improved outcomes for patients with melanoma and breast cancer. The potential utility of targeting GPNMB in osteosarcoma was explored.

Methods

GPNMB protein expression was evaluated by immunohistochemistry in human osteosarcoma tumor samples and by enzyme‐linked immunosorbent assay (ELISA) in osteosarcoma cell lines. mRNA expression was measured by quantitative PCR in primary osteosarcoma samples and cell lines. Surface GPNMB expression was evaluated by flow cytometry and correlated with in vitro and in vivo cytotoxicity of glembatumumab vedotin.

Results

Sixty seven human osteosarcoma samples were evaluated by immunohistochemistry, including 12 samples from initial biopsy, 38 samples from definitive surgery, and 17 from the time of disease recurrence. GPNMB was expressed in 92.5% (62/67) of osteosarcoma samples. All primary osteosarcoma samples expressed high levels of GPNMB mRNA. Glembatumumab induced cytotoxic effects in 74% (14/19) of osteosarcoma cell lines, and GPNMB protein levels correlated with glembatumumab in vitro cytotoxicity (r = −0.46, P = 0.04). All osteosarcoma cell lines demonstrated surface GPNMB expression.

Conclusions

GPNMB is expressed in osteosarcoma and targeting GPNMB with the antibody‐drug conjugate glembatumumab vedotin demonstrates osteosarcoma cytotoxic activity. Clinical trials are indicated to assess the efficacy of targeting GPNMB in patients with osteosarcoma. Pediatr Blood Cancer 2015; 9999:1–7 © 2015 Wiley Periodicals, Inc.
Temozolomide Treatment for Pediatric Refractory Anaplastic Ependymoma with Low MGMT Protein Expression
Authors: Komori Kazutoshi , Yanagisawa Ryu , Miyairi Yosuke , Sakashita Kazuo , Shiohara Masaaki , Fujihara Ikuko , Morita Daisuke , Nakamura Tomohiko , Ogiso Yoshifumi , Sano Kenji , Shirahata Mitsuaki , Fukuoka Kohei , Ichimura Koichi , Shigeta Hiroaki
Published: August 2015

The benefit of postoperative chemotherapy for anaplastic ependymoma remains unknown. We report two pediatric patients with refractory anaplastic ependymoma treated with temozolomide (TMZ). We did not detect O6‐methylguanine‐DNA methyltransferase (MGMT) promoter methylation in tumor samples; however, MGMT protein expression was low. With TMZ treatment, one patient had a 7‐month complete remission; the other, stable disease for 15 months. Three other patients did not respond to TMZ; two had high and one low MGMT expression, and two showed no MGMT promoter methylation. These findings suggest that TMZ may be effective for pediatric refractory anaplastic ependymoma with low MGMT protein expression. Pediatr Blood Cancer © 2015 Wiley Periodicals, Inc.
Mechanical properties of surface‐modified ultra‐high molecular weight polyethylene fiber reinforced natural rubber composites
Authors: Li Weiwei , Li Ruipei , Li Chunyang , Chen Zhong‐Ren , Zhang Li
Published: August 2015

The mechanical properties of ultra‐high molecular weight polyethylene (UHMWPE) fibers reinforced natural rubber (NR) composites were determined, and the effects of fiber surface treatment and fiber mass fraction on the mechanical properties of the composites were investigated. Chromic acid was used to modify the UHMWPE fibers, and the results showed that the surface roughness and the oxygen‐containing groups on the surface of the fibers could be effectively increased. The NR matrix composites were prepared with as‐received and chromic acid treated UHMWPE fibers added 0–6 wt%. The treated UHMWPE fibers increased the elongation at break, tear strength, and hardness of the NR composites, especially the tensile stress at a given elongation, but reduced the tensile strength. The elongation at break increased markedly with increasing fiber mass fraction, attained maximum values at 3.0 wt%, and then decreased. The tear strength and hardness exhibited continuous increase with increasing the fiber content. Several microfibrillations between the fiber and NR matrix were observed from SEM images of the fractured surfaces of the treated UHMWPE fibers/NR composites, which meant that the interfacial adhesion strength was improved. POLYM. COMPOS., 38:1215–1220, 2017. © 2015 Society of Plastics Engineers
An efficient optimal method for a 2D strain estimation of ultrasound tissue‐mimicking material phantom
Authors: Zhu Haijiang , Zhou Shifeng , Yang Ping , He Longbiao , Zhou Jinglin
Published: August 2015

Elastography is a relatively new technique in ultrasound or magnetic resonance imaging (MRI). This fact has motivated many investigators to investigate the preparation of tissue‐mimicking material and the imaging of the tissue‐mimicking phantom. In this article, an efficient numerical optimization method based on Quasi‐Newton algorithm is presented for calculating a 2D strain image of tissue‐mimicking material (TMM) sample. The first step in the proposed method is that the initial values for the displacement fields are estimated using the cross‐correlation method. Then, the numerical optimization method based on the Quasi‐Newton algorithm is adopted to improve the displacement and strain through selecting one moving subfield. The basic idea of the proposed method is to construct an object function based on a homogeneous affine transformation between pre‐ and post‐compression data and optimize the displacement and strain image for the initial displacement data. For a validation, the results of the proposed method compare with those of other numerical optimization methods. The simulated and experimental results demonstrate the potential of our two‐step strategy for the strain imaging of tissue‐mimicking phantom with high efficiency and accuracy. POLYM. ENG. SCI., 55:2751–2760, 2015. © 2015 Society of Plastics Engineers
Preparation and characterization of pH‐sensitive hydrogel microspheres based on atom transfer radical polymerization
Authors: Zhu Hong‐Zheng , You Li‐Qin , Wei Hong‐Liang , Wang Guo‐Feng , Chu Hui‐Juan , Zhu Jing , He Juan
Published: August 2015

In this study, we prepared pH‐sensitive hydrogel microspheres by means of atom transfer radical polymerization of hydroxyethyl methacrylate and 4‐vinylpyridine in inverse emulsion, using poly (ethylene glycol) dimethylacrylate as a crosslinker. One‐factor experiment was used to optimize conditions of preparing microspheres and the resulting conditions were presented. The microspheres were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, scanning electron microscopy, and so forth. The swelling behavior of the as‐prepared microspheres was studied by a classic gravimetric method. Afterward, daidzein was used as a model drug and related release mechanism was investigated. The diffusional coefficients and the corresponding kinetic parameters of chosen mathematical models for fitting drug release were calculated, which indicated drug release accorded with anomalous (non‐Fickian) diffusion mechanism. POLYM. ENG. SCI., 55:2775–2782, 2015. © 2015 Society of Plastics Engineers
Synthesis of strigolactones, a strategic account
Authors: Zwanenburg Binne , Ćavar Zeljković Sanja , Pospíšil Tomáš
Published: August 2015

Strigolactones (SLs) constitute a new class of plant hormones that have received growing interest in recent years. They firstly became known as signalling molecules for host recognition by parasitic plants, and for symbiosis of plants with arbuscular mycorrhizal fungi. Furthermore, they are involved in numerous physiological processes in plants, such as the regulation of plant architecture and the response to abiotic factors. SLs are produced by plants in extremely low quantities, and they may be unstable during the purification process. Therefore, their total synthesis is highly relevant for confirming the structures assigned on the basis of spectroscopic and other physical data. A second important theme in SL research is the design and synthesis of SL analogues that have a simplified structure while still featuring the essential bioproperties. This review summarises the strategy and synthesis of naturally occurring SLs, and the design and synthesis of SL analogues with appreciable bioactivity. © 2015 Society of Chemical Industry
Velocity‐free attitude stabilization with inertial vector measurements
Authors: Benziane Lotfi , Benallegue Abdelaziz , Chitour Yacine , Tayebi Abdelhamid
Published: August 2015

This paper deals with the attitude stabilization problem of a rigid body, where neither the angular velocity nor the attitude is used in the feedback; only body‐referenced vector measurements are needed. The proposed control scheme is based on an angular velocity observer‐like system relying solely on vector measurements. The proposed controller ensures almost global asymptotic stability and provides some interesting performance properties through an appropriate tuning of the control gains. The performance and effectiveness of the proposed control scheme are illustrated via simulation results where the control gains are adjusted using a nonlinear optimization. Copyright © 2015 John Wiley & Sons, Ltd.
Provably secure unbounded multi‐authority ciphertext‐policy attribute‐based encryption
Authors: Li Qi , Ma Jianfeng , Li Rui , Xiong Jinbo , Liu Ximeng
Published: August 2015

Multi‐authority attribute‐based encryption (ABE) is a generation of ABE where the descriptive attributes are managed by different authorities. In current multi‐authority ABE schemes, the scale of attribute universe employed in encryption is restricted by various predefined thresholds. In this paper, we propose an unbounded multi‐authority ciphertext‐policy ABE system without such restriction. Our scheme consists of multiple attribute authorities (AAs), one central authority (CA), and users labeled by the set of attributes. Each AA governs a different universe of attributes and operates separately. Moreover, there is no cooperation between the CA and AAs. To provide the private keys for a user, the AAs first issue partial attribute‐related keys according to the attributes; the CA then issues identity‐related keys and links these attribute‐keys with the user's global identifier. Both the identity‐related and the linked attribute‐related keys will be used in decryption. The proposed multi‐authority ciphertext‐policy ABE scheme can support arbitrary linear secret sharing scheme as the access policy. Performance analysis and security proof indicate that our scheme is efficient and secure. Copyright © 2015 John Wiley & Sons, Ltd.
On the practice of ignoring center‐patient interactions in evaluating hospital performance
Authors: Varewyck Machteld , Vansteelandt Stijn , Eriksson Marie , Goetghebeur Els
Published: August 2015

We evaluate the performance of medical centers based on a continuous or binary patient outcome (e.g., 30‐day mortality). Common practice adjusts for differences in patient mix through outcome regression models, which include patient‐specific baseline covariates (e.g., age and disease stage) besides center effects. Because a large number of centers may need to be evaluated, the typical model postulates that the effect of a center on outcome is constant over patient characteristics. This may be violated, for example, when some centers are specialized in children or geriatric patients. Including interactions between certain patient characteristics and the many fixed center effects in the model increases the risk for overfitting, however, and could imply a loss of power for detecting centers with deviating mortality. Therefore, we assess how the common practice of ignoring such interactions impacts the bias and precision of directly and indirectly standardized risks. The reassuring conclusion is that the common practice of working with the main effects of a center has minor impact on hospital evaluation, unless some centers actually perform substantially better on a specific group of patients and there is strong confounding through the corresponding patient characteristic. The bias is then driven by an interplay of the relative center size, the overlap between covariate distributions, and the magnitude of the interaction effect. Interestingly, the bias on indirectly standardized risks is smaller than on directly standardized risks. We illustrate our findings by simulation and in an analysis of 30‐day mortality on Riksstroke. © 2015 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd.
Chemical Vapor Deposition of High‐Quality and Atomically Layered ReS2
Authors: He Xuexia , Liu Fucai , Hu Peng , Fu Wei , Wang Xingli , Zeng Qingsheng , Zhao Wu , Liu Zheng
Published: August 2015

Recently, anisotropic 2D materials, such as black phosphorus and rhenium disulfides (ReS2), have attracted a lot attention because of their unique applications on electronics and optoelectronics. In this work, the direct growth of high‐quality ReS2 atomic layers and nanoribbons has been demonstrated by using chemical vapor deposition (CVD) method. A possible growth mechanism is proposed according to the controlled experiments. The CVD ReS2‐based filed‐effect transistors (FETs) show n‐type semiconducting behavior with a current on/off ratio of ≈106 and a charge carrier mobility of ≈9.3 cm2 Vs−1. These results suggested that the quality of CVD grown ReS2 is comparable to mechanically exfoliated ReS2, which is also further supported by atomic force microscopy imaging, high‐resolution transmission electron microscopy imaging and thickness‐dependent Raman spectra. The study here indicates that CVD grown ReS2 may pave the way for the large‐scale fabrication of ReS2‐based high‐performance optoelectronic devices, such as anisotropic FETs and polarization detection.
Longitudinal functional data analysis
Authors: Park So Young , Staicu Ana‐Maria
Published: August 2015

We consider dependent functional data that are correlated because of a longitudinal‐based design: each subject is observed at repeated times and at each time, a functional observation (curve) is recorded. We propose a novel parsimonious modelling framework for repeatedly observed functional observations that allows to extract low‐dimensional features. The proposed methodology accounts for the longitudinal design, is designed to study the dynamic behaviour of the underlying process, allows prediction of full future trajectory and is computationally fast. Theoretical properties of this framework are studied, and numerical investigations confirm excellent behaviour in finite samples. The proposed method is motivated by and applied to a diffusion tensor imaging study of multiple sclerosis. Copyright © 2015 John Wiley & Sons, Ltd.
NEDD4 Regulates PAX7 Levels Promoting Activation of the Differentiation Program in Skeletal Muscle Precursors
Authors: Bustos Francisco , de la Vega Eduardo , Cabezas Felipe , Thompson James , Cornelison D.D.W. , Olwin Bradley B. , Yates John R. , Olguín Hugo C.
Published: August 2015

The transcription factor Pax7 regulates skeletal muscle stem cell (satellite cells) specification and maintenance through various mechanisms, including repressing the activity of the muscle regulatory factor MyoD. Hence, Pax7-to-MyoD protein ratios can determine maintenance of the committed-undifferentiated state or activation of the differentiation program. Pax7 expression decreases sharply in differentiating myoblasts but is maintained in cells (re)acquiring quiescence, yet the mechanisms regulating Pax7 levels based on differentiation status are not well understood. Here we show that Pax7 levels are directly regulated by the ubiquitin-ligase Nedd4. Our results indicate that Nedd4 is expressed in quiescent and activated satellite cells, that Nedd4 and Pax7 physically interact during early muscle differentiation—correlating with Pax7 ubiquitination and decline—and that Nedd4 loss of function prevented this effect. Furthermore, even transient nuclear accumulation of Nedd4 induced a drop in Pax7 levels and precocious muscle differentiation. Consequently, we propose that Nedd4 functions as a novel Pax7 regulator, which activity is temporally and spatially controlled to modulate the Pax7 protein levels and therefore satellite cell fate. Stem Cells  2015;33:3138—3151
In Vitro Conditioned Bone Marrow-Derived Mesenchymal Stem Cells Promote De Novo Functional Enteric Nerve Regeneration, but Not Through Direct-Transdifferentiation
Authors: Lin Rong , Ding Zhen , Ma Huan , Shi Huiying , Gao Yuanjun , Qian Wei , Shi Weina , Sun Zhaoli , Hou Xiaohua , Li Xuhang
Published: August 2015

Injury or neurodegenerative disorders of the enteric nervous system (ENS) cause gastrointestinal dysfunctions for which there is no effective therapy. This study, using the benzalkonium chloride-induced rat gastric denervation model, aimed to determine whether transplantation of bone marrow-derived mesenchymal stem cells (BMSC) could promote ENS neuron regeneration and if so, to elucidate the mechanism. Fluorescently labeled BMSC, isolated from either WT (BMSC labeled with bis-benzimide [BBM]) or green fluorescent protein (GFP)-transgenic rats, were preconditioned in vitro using fetal gut culture media containing glial cell-derived neurotrophic factor (GDNF), and transplanted subserosally into the denervated area of rat pylorus. In the nerve-ablated pylorus, grafted BMSC survived and migrated from the subserosa to the submucosa 28 days after transplantation, without apparent dedifferentiation. A massive number of PGP9.5/NSE/HuC/D/Tuj1-positive (but GFP- and BBM-negative) neurons were effectively regenerated in denervated pylorus grafted with preconditioned BMSC, suggesting that they were regenerated de novo, not originating from trans-differentiation of the transplanted BMSC. BMSC transplantation restored both basal pyloric contractility and electric field stimulation-induced relaxation. High levels of GDNF were induced in both in vitro-preconditioned BMSC as well as the previously denervated pylorus after transplantation of preconditioned BMSC. Thus, a BMSC-initiated GDNF-positive feedback mechanism is suggested to promote neuron regeneration and growth. In summary, we have demonstrated that allogeneically transplanted preconditioned BMSC initiate de novo regeneration of gastric neuronal cells/structures that in turn restore gastric contractility in pylorus-denervated rats. These neuronal structures did not originate from the grafted BMSC. Our data suggest that preconditioned allogeneic BMSC may have therapeutic value in treating enteric nerve disorders. Stem Cells  2015;33:3545–3557
Bcl3 Bridges LIF-STAT3 to Oct4 Signaling in the Maintenance of Naïve Pluripotency
Authors: Chen Chen-Yun , Lee Desy S. , Yan Yu-Ting , Shen Chia-Ning , Hwang Shiaw-Min , Lee Sho Tone , Hsieh Patrick C.H.
Published: August 2015

Leukemia inhibitory factor (LIF) regulates mouse embryonic stem cell (mESC) pluripotency through STAT3 activation, but the downstream signaling remains largely unelucidated. Using cDNA microarrays, we verified B cell leukemia/lymphoma 3 (Bcl3) as the most significantly downregulated factor following LIF withdrawal in mESCs. Bcl3 knockdown altered mESC morphology, reduced expression of pluripotency genes including Oct4, Sox2, and Nanog, and downregulated DNA binding of acetylated histone 3 and RNA polymerase II on the Oct4 promoter. Conversely, Bcl3 overexpression partially prevented cell differentiation and promoted Oct4 and Nanog promoter activities. Furthermore, coimmunoprecipitation and chromatin immunoprecipitation experiments demonstrated that Bcl3 regulation of mESC pluripotency may be through its association with Oct4 and β-catenin and its promoter binding capability. These results establish that Bcl3 positively regulates pluripotency genes and thus shed light on the mechanism of Bcl3 as a downstream molecule of LIF/STAT3 signaling in pluripotency maintenance. Stem Cells  2015;33:3468–3480
Informal science institutions and learning to teach: An examination of identity, agency, and affordances
Authors: Adams Jennifer D. , Gupta Preeti
Published: August 2015

Informal science education institutions play an important in the public understanding of science and, because of this are well‐positioned to positively impact science teacher education. Informal science institutions (ISIs) have a range of affordances that could contribute to learner‐centered science teacher identity development. This article describes research from a clinical experience in a museum where teacher candidates engaged visitors in learning dialogs around objects on a moveable cart in an exhibit. We describe how working in informal settings and learning to use the affordances of that setting supports aspiring teachers to connect theory to practice in ways that developed Spielraum in that is student‐centered, responsive to the needs of learners, and allows for the imagination future selves and classrooms that are conducive to maintaining these identities. This research supports the critical role that ISIs could play in teacher education, especially during the clinical phase where teacher candidates are forming initial notions about their identities, about the self who teaches. © 2015 Wiley Periodicals, Inc. J Res Sci Teach 54: 121–138, 2017
From cyst to tubule: innovations in vertebrate spermatogenesis
Authors: Yoshida Shosei
Published: August 2015

Although vertebrates share many common traits, their germline development and function exhibit significant divergence. In particular, this article focuses on their spermatogenesis. The fundamental elements that constitute vertebrate spermatogenesis and the evolutionary changes that occurred upon transition from water to land will be discussed. The life‐long continuity of spermatogenesis is supported by the function of stem cells. Series of mitotic and meiotic germ cell divisions are ‘incomplete’ due to incomplete cytokinesis, forming syncytia interconnected via intercellular bridges (ICBs). Throughout this process, germ cells are supported by appropriate microenvironments established primarily by somatic Sertoli cells. In anamniotes (fish and amphibians) spermatogenesis progresses in cysts, in which developing germ cell syncytia are individually encapsulated by Sertoli cells. Accordingly, Sertoli cells undergo turnover with germ cells that they nourish. This mode of cystic spermatogenesis is also observed in nonvertebrates as insects. In amniotes (reptiles, birds, and mammals), however, Sertoli cells do not turn over but comprise a persistent structure of seminiferous tubules. Sertoli cells nourish different stages of germ cells simultaneously in distinct regions of their surface. This function of Sertoli cells is spatiotemporally orchestrated, and the seminiferous epithelial cycle and spermatogenic wave make the seminiferous tubules a high‐throughput factory for sperm production. Furthermore, contrary to the organized differentiating cells, undifferentiated spermatogonia that comprise the stem cell compartment exhibit active motion over the basal layer of seminiferous tubules and the frequent breakdown of ICBs. Thus, amniote seminiferous tubules represent a typical facultative (or open) niche environment without a stem cell tethering anatomically defined niche.WIREs Dev Biol2016, 5:119–131. doi: 10.1002/wdev.204

This article is categorized under:

Gene Expression and Transcriptional Hierarchies > Cellular Differentiation

Adult Stem Cells, Tissue Renewal, and Regeneration > Tissue Stem Cells and Niches

Adult Stem Cells, Tissue Renewal, and Regeneration > Environmental Control of Stem Cells