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https://www.readbyqxmd.com/read/28532131/investigation-into-the-anomalous-temperature-characteristics-of-ingan-double-quantum-well-blue-laser-diodes-using-numerical-simulation
#1
Han-Youl Ryu
GaN-based blue laser diodes (LDs) may exhibit anomalous temperature characteristics such as a very high characteristic temperature (T 0) or even negative T 0. In this work, temperature-dependent characteristics of GaN-based blue LDs with InGaN double quantum well (QW) structures were investigated using numerical simulations. The temperature-dependent threshold current is found to become increasingly anomalous as the thickness or doping concentration of the barrier layer between QWs increases. For a properly chosen barrier thickness and doping concentration, very high T 0 of >10,000 K can be obtained...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28532123/origin-of-dislocation-luminescence-centers-and-their-reorganization-in-p-type-silicon-crystal-subjected-to-plastic-deformation-and-high-temperature-annealing
#2
Bohdan Pavlyk, Markiyan Kushlyk, Dmytro Slobodzyan
Changes of the defect structure of silicon p-type crystal surface layer under the influence of plastic deformation and high temperature annealing in oxygen atmosphere were investigated by deep-level capacitance-modulation spectroscopy (DLCMS) and IR spectroscopy of molecules and atom vibrational levels. Special role of dislocations in the surface layer of silicon during the formation of its energy spectrum and rebuilding the defective structure was established. It is shown that the concentration of linear defects (N ≥ 10(4) cm(-2)) enriches surface layer with electrically active complexes (dislocation-oxygen, dislocation-vacancy, and dislocation-interstitial atoms of silicon) which are an effective radiative recombination centers...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28532118/facile-synthesis-of-polymeric-fluorescent-organic-nanoparticles-based-on-the-self-polymerization-of-dopamine-for-biological-imaging
#3
Yingge Shi, Ruming Jiang, Meiying Liu, Lihua Fu, Guangjian Zeng, Qing Wan, Liucheng Mao, Fengjie Deng, Xiaoyong Zhang, Yen Wei
Polymeric fluorescent organic nanoparticles (polymer-FONs) have raised considerable research attention for biomedical applications owing to their advantages as compared with fluorescent inorganic nanoparticles and small organic molecules. In this study, we presented an efficient, facile and environment-friendly strategy to produce polymer-FONs, which relied on the self-polymerization of dopamine and polyethyleneimine (PEI) in rather mild conditions. To obtain the final polymer-FONs, aldehyde group-containing copolymers (named as poly(UA-co-PEGMA)) were synthesized by reversible addition-fragmentation chain-transfer polymerization using polyethylene glycol methyl ether methacrylate (PEGMA) and 1-undecen-10-al (UA) as monomers...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532113/nanofibers-of-human-tropoelastin-inspired-peptides-structural-characterization-and-biological-properties
#4
Valeria Secchi, Stefano Franchi, Marco Fioramonti, Giovanni Polzonetti, Giovanna Iucci, Brigida Bochicchio, Chiara Battocchio
Regenerative medicine is taking great advantage from the use of biomaterials in the treatments of a wide range of diseases and injuries. Among other biomaterials, self-assembling peptides are appealing systems due to their ability to spontaneously form nanostructured hydrogels that can be directly injected into lesions. Indeed, self-assembling peptide scaffolds are expected to behave as biomimetic matrices able to surround cells, to promote specific interactions, and to control and modify cell behavior by mimicking the native environment as well...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532111/surface-biofunctionalization-of-three-dimensional-porous-poly-lactic-acid-scaffold-using-chitosan-ogp-coating-for-bone-tissue-engineering
#5
Sen Zeng, Jianhua Ye, Zhixiang Cui, Junhui Si, Qianting Wang, Xiaofeng Wang, Kaiping Peng, Wenzhe Chen
As one of the stimulators on bone formation, osteogenic growth peptide (OGP) improves both proliferation and differentiation of the bone cells in vitro and in vivo. The aim of this work was the preparation of three dimensional porous poly(lactic acid) (PLA) scaffold with high porosity from PLA-dioxane-water ternary system with the use of vacuum-assisted solvent casting, phase separation, solvent extraction and particle leaching methods. Then, by surface coating of PLA scaffold with chitosan (CS)/OGP solution, biofunctionalization of PLA scaffold had been completed for application in bone regeneration...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532102/islet-encapsulated-implantable-composite-hollow-fiber-membrane-based-device-a-bioartificial-pancreas
#6
Rohit S Teotia, Sachin Kadam, Atul Kumar Singh, Surendra Kumar Verma, Ashutosh Bahulekar, Sujata Kanetkar, Jayesh Bellare
Islets from xeno-sources and islet like clusters derived from autologus stem cells have emerged as alternatives to cadaveric pancreas used for treatment of type 1 diabetes. However, the immuno-isolation of these islets from the host immune system suffers from the issue of biocompatibility and hypoxia. To overcome the issues of immunobarrier biocompatibility, we developed a Polysulfone (Psf)/TPGS composite hollow fiber membrane (HFM) using a hollow fiber spinning pilot plant specially developed for this purpose...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532097/influence-of-telopeptides-on-the-structural-and-physical-properties-of-polymeric-and-monomeric-acid-soluble-type-i-collagen
#7
Róisín Holmes, Steve Kirk, Giuseppe Tronci, Xuebin Yang, David Wood
Currently two factors hinder the use of collagen as building block of regenerative devices: the limited mechanical strength in aqueous environment, and potential antigenicity. Polymeric collagen is naturally found in the cross-linked state and is mechanically tougher than the monomeric, acid-soluble collagen ex vivo. The antigenicity of collagen, on the other hand, is mainly ascribed to inter-species variations in amino acid sequences of the non-helical terminal telopeptides. These telopeptides can be removed through enzymatic treatment to produce atelocollagen, although the effect of this cleavage on triple helix organization, amino acidic composition and thermal properties is often disregarded...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532090/in-situ-synthesis-of-bilayered-gradient-poly-vinyl-alcohol-hydroxyapatite-composite-hydrogel-by-directional-freezing-thawing-and-electrophoresis-method
#8
Cui Su, Yunlan Su, Zhiyong Li, Muhammad Abdul Haq, Yong Zhou, Dujin Wang
Bilayered poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogels with anisotropic and gradient mechanical properties were prepared by the combination of directional freezing-thawing (DFT) and electrophoresis method. Firstly, PVA hydrogels with aligned channel structure were prepared by the DFT method. Then, HA nanoparticles were in situ synthesized within the PVA hydrogels via electrophoresis. By controlling the time of the electrophoresis process, a bilayered gradient hydrogel containing HA particles in only half of the gel region was obtained...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532086/freeze-casting-for-plga-carbonated-apatite-composite-scaffolds-structure-and-properties
#9
M Schardosim, J Soulié, D Poquillon, S Cazalbou, B Duployer, C Tenailleau, C Rey, R Hübler, C Combes
This paper focuses on the fabrication of three-dimensional porous PLGA-biomimetic carbonated apatite composite scaffolds by freeze-casting and using dimethyl carbonate as a solvent. Several charge/polymer ratios were tested in order to finely understand the influence of the filler rate on the scaffold porosity and mechanical and degradation properties using complementary characterization techniques (SEM, mercury porosimetry and X-ray microtomography). It was demonstrated that the apatite ratio within the composite scaffold has a strong influence in terms of architecture, material cohesion, mechanical properties and in vitro degradation properties...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532083/effects-for-rapid-conversion-from-abalone-shell-to-hydroxyapaptite-nanosheets-by-ionic-surfactants
#10
Shengnan Zhong, Zhenliang Wen, Jingdi Chen, Qian Li, Xuetao Shi, Shinnjyh Ding, Qiqing Zhang
Hydroxyapatite (HAP) has been widely used for repairing or substituting human hard tissues. In this paper, two typical ionic surfactants, cation hexadecyltrimethylammonium bromide (CTAB) and anion sodium dodecyl sulfate (SDS), were used for rapid conversion of HAP from abalone shell. From field emission scanning electron microscopy (FESEM), the prepared HAP is flake-like structure. From X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal analysis, these samples contain a small amount of calcium carbonate whose content gradually increases by increasing the surfactants...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532079/nerve-growth-factor-loaded-heparinized-cationic-solid-lipid-nanoparticles-for-regulating-membrane-charge-of-induced-pluripotent-stem-cells-during-differentiation
#11
Yung-Chih Kuo, Rajendiran Rajesh
Nerve growth factor (NGF)-loaded heparinized cationic solid lipid nanoparticles (NGF-loaded HCSLNs) were developed using heparin-stearic acid conjugate, cacao butter, cholesterol, stearylamine (SA), and esterquat 1 (EQ 1). The effect of cationic lipids and lipid matrix composition on the particle size, particle structure, surface molecular composition, chemical structure, electrophoretic mobility, and zeta potential of HCSLNs was investigated. The effect of HCSLNs on the membrane charge of induced pluripotent stem cells (iPSCs) was also studied...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532078/enhancement-of-fibroblast-growing-on-the-mannosylated-surface-of-cellulose-membranes
#12
Simone Birkheur, Paula Cristina de Sousa Faria-Tischer, Cesar A Tischer, Elisângela Flávia Pimentel, Marcio Fronza, Denise Coutinho Endringer, Anna Paola Butera, Renato Márcio Ribeiro-Viana
Bacterial cellulose membrane is a biomaterial with high value in the biomedical field. Many groups have been making efforts to promote chemical modifications of its structure and, consequently, add new characteristics. Recently, our group has developed a methodology to insert monoester succinic acid in bacterial cellulose membrane without disrupting the microfibril network and bind a protein on it. Considering the role of carbohydrates in the molecular recognition process in biological events, we continued these studies by inserting covalently multiples copies of aryl monosaccharide to bacterial cellulose succinylated and to study the in vitro tissue compatibility using fibroblasts...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532073/fabrication-of-vinyl-organosilicon-poly-n-n-4-5-dihydroxy-1-2-phenylene-bis-methylene-bisacrylamide-core-shell-antibacterial-agent
#13
Zhijia Zhang, Xiaole Zhao, Yingchun Su, Defeng Xing, Xiaojun Han
We demonstrate that antibacterial agent N, N'-[(4, 5-dihydroxy-1, 2-phenylene)bis(methylene)]bisacrylamide (OHABA) can be assembled on the surface of vinyl organosilicon nanospheres (VOSNs) by atom transfer radical polymerization (ATRP). Chemically cross-linked vinyl organosilicon cores were facilely fabricated by sol-gel method as support, which densely grafted poly-OHABA (POHABA) as shells. Antibacterial assessment test results revealed that POHABA-based core@shell structure displayed high antibacterial performance, long-term stability, and kept broad-spectrum antibacterial effect of against Gram-negative and Gram-positive bacteria...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532070/ribose-mediated-crosslinking-of-collagen-hydroxyapatite-hybrid-scaffolds-for-bone-tissue-regeneration-using-biomimetic-strategies
#14
Gopal Shankar Krishnakumar, Natalia Gostynska, Elisabetta Campodoni, Massimiliano Dapporto, Monica Montesi, Silvia Panseri, Anna Tampieri, Elizaveta Kon, Maurilio Marcacci, Simone Sprio, Monica Sandri
This study explores for the first time the application of ribose as a highly biocompatible agent for the crosslinking of hybrid mineralized constructs, obtained by bio-inspired mineralization of self-assembling Type I collagen matrix with magnesium-doped-hydroxyapatite nanophase, towards a biomimetic mineralized 3D scaffolds (MgHA/Coll) with excellent compositional and structural mimicry of bone tissue. To this aim, two different crosslinking mechanisms in terms of pre-ribose glycation (before freeze drying) and post-ribose glycation (after freeze drying) were investigated...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532063/biodegradable-galactitol-based-crosslinked-polyesters-for-controlled-release-and-bone-tissue-engineering
#15
Janeni Natarajan, Sahitya Movva, Giridhar Madras, Kaushik Chatterjee
Various classes of biodegradable polymers have been explored towards finding alternates for the existing treatments for bone disorders. In this framework, two families of polyesters using an array of crosslinkers were synthesized. One was based on galactiol/adipic acid and the other based on galactitol/dodecanedioic acid. The structures of the polymers were confirmed by FTIR and further confirmed by (1)H NMR. DSC showed that the polymers were amorphous and the glass transition temperature increased with increase in crosslinking...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532061/wound-healing-effect-of-bioactive-ion-released-from-mg-smectite
#16
Yu Sasaki, Gulsan Ara Sathi, Osamu Yamamoto
Bioactive ions like Mg(2+) and Si(4+) have been known as promotion factors of tissue regeneration. In the present work, Mg-smectite, consisting of Mg(2+) and Si(4+) ions, was synthesized by a solution process, and evaluated for the efficiency of the powder on wound healing in rats. White precipitates were obtained by mixing a magnesium chloride hexahydrate solution and a sodium silicate hexahydrate solution at room temperature. The precipitates mixed with a NaOH aqueous solution were subjected to hydrothermal reaction, and finally crystalline Mg-smectite powder was obtained...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532060/design-and-characterization-of-biodegradable-macroporous-hybrid-inorganic-organic-polymer-for-orthopedic-applications
#17
Sunita PremVictor, Jibin Kunnumpurathu, M G Gayathri Devi, K Remya, Vineeth M Vijayan, Jayabalan Muthu
We have engineered hybrid polymer products based on a hybrid inorganic-organic comacromer consisting of hydroxyapatite (HA), carboxyl terminated polypropylene fumarate (CTPPF), PEG300 and ascorbic acid (AA) as a bone graft material. The integration and the spatial distribution of HA in the polymer backbone were facilitated by silanisation and 1-ethyl-3-(-3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) coupling technique. These comacromers and crosslinked polymer products were characterized by Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), Scanning electron microscopy (SEM) and Raman mapping techniques...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532056/stiff-porous-scaffolds-from-magnetized-alumina-particles-aligned-by-magnetic-freeze-casting
#18
Michael B Frank, Steven E Naleway, Tsuk Haroush, Chin-Hung Liu, Sze Hei Siu, Jerry Ng, Ivan Torres, Ali Ismail, Keyur Karandikar, Michael M Porter, Olivia A Graeve, Joanna McKittrick
Bone consists of a hard mineral phase and a compliant biopolymer phase resulting in a composite material that is both lightweight and strong. Osteoporosis that degrades spongy bone preferentially over time leads to bone brittleness in the elderly. A porous ceramic material that can mimic spongy bone for a one-time implant provides a potential solution for the future needs of an aging population. Scaffolds made by magnetic freeze casting resemble the aligned porosity of spongy bone. A magnetic field applied throughout freezing induces particle chaining and alignment of lamellae structures between growing ice crystals...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532053/functionalized-fe3o4-graphene-oxide-nanocomposites-with-hairpin-aptamers-for-the-separation-and-preconcentration-of-trace-pb-2-from-biological-samples-prior-to-determination-by-icp-ms
#19
Mojtaba Shamsipur, Leila Farzin, Mahmoud Amouzadeh Tabrizi, Shahab Sheibani
Lead (Pb) as a topically poisonous metal represents a serious threat to the ecological environment and especially to human beings. Therefore, it is urgent to develop a rapid and reliable monitoring technique for this heavy metal in the environmental samples. In the present study, we have designed a selective and sensitive method for the determination of ultratrace contents of Pb(2+) in biological samples, based on the guanine (G)-quadruplex formed by the aptamer with hairpin structure and Pb(2+). For this purpose, Pb(2+) specific aptamer serving as affinity probe to capture and separate trace amounts of the analyte, was covalently linked to Fe3O4/graphene oxide (GO) surface by using a suitable cross-linking agent...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532052/poly-%C3%AE%C2%B5-caprolactone-modification-via-surface-initiated-atom-transfer-radical-polymerization-with-bio-inspired-phosphorylcholine
#20
Liu He, Lei Huang, Songbai Zhang, Yuanwei Chen, Xianglin Luo
Bio-inspired phosphorylcholine modification on material surface has shown great promise in constructing biocompatible materials. In this study, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) was grown on poly(ε-caprolactone) (PCL) surface in order to suppress protein adsorption and cells adhesion and to improve blood compatibility. The initiator for surface initiated atom transfer radical polymerization (SI-ATRP) was covalently tethered on PCL surface and then PMPC brushes with diverse graft amounts were grafted to PCL film...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
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