bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and synthesis study of the thermo‐sensitive copolymer carrier of penicillin G acylase
Authors: Li Ke , Chen Zhen Bin , Liu Dong Lei , Zhang Lin , Tang Zhenghua , Wang Zhe , Zhao Yu , Liu Zhen 
Published: April 2018

Reversible‐addition‐fragmentation chain transfer polymerization method was adopted here in this study to prepare a series of thermo‐sensitive tri‐block copolymer carrier, poly(N,N‐diethylacrylamide‐b‐β‐hydroxyethyl methacrylate‐b‐glycidyl methacrylate), PDEA‐b‐PHEMA‐b‐PGMA (named as DHG). Their structures and temperature sensitivity performances were further characterized by the nuclear magnetic resonance, the gel permeation chromatography, and the fluorescence spectroscopy, respectively. It has been identified that the synthesis reaction of tri‐block copolymer was living polymerization. The thermo‐sensitivity study suggested that 2 monomers, β‐hydroxyethyl methacrylate and glycidyl methacrylate, played key roles on the lower critical solution temperature performance. Finally, above block copolymer was conscripted to immobilize penicillin G acylase; relationships among the number‐average molar weight
of the 2 monomer, β‐hydroxyethyl methacrylate and glycidyl methacrylate, loading (L), and activity recover rate (Ar) of immobilized PGA were investigated. And the results showed that L and Ar arrived at 19 502 U and 92%, respectively.
First trimester screening for major cardiac defects based on the ductus venosus flow in fetuses with trisomy 21
Authors: Wagner Philipp , Sonek Jiri , Eberle Katrin , Abele Harald , Hoopmann Markus , Prodan Natalia , Kagan Karl Oliver 
Published: April 2018

AbstractObjectiveTo examine whether in fetuses with trisomy 21 (T21), the ductus venosus (DV) flow differs in presence of a major cardiac defect (congenital cardiac defect [CHD]) and whether this affects the risk distribution in first trimester screening for T21.MethodsThis retrospective study included pregnant women who underwent first trimester screening. This involves an examination of the crown‐rump length, the nuchal translucency, the ductus venosus (DV) flow, and the heart. Three groups of fetuses were examined: euploid without CHD, T21 with CHD, and T21 without CHD. We examined the DV pulsatility index for veins, the direction of the a‐wave, and ratios of velocities: v/S, v/D, a/S, a/D, and S/D.ResultsThe study population consisted of 410 euploid fetuses and 136 with T21 (51 with CHD and 85 without CHD). In the 3 groups, the a‐wave was reversed in 3.2%, 66.7%, and 57.6%. The DV flow ratios in T21 with and without CDH were significantly different compared with normal fetuses. When comparing the ratios between the 2 T21 groups, only the a/S and a/D ratio were significantly different. The risk distributions in screening for T21 with and without CDH were similar.ConclusionThere are some small differences in the DV flow of T21 fetuses with and without CHD, but they are not clinically useful.
Exploration of the fifth position of leu‐enkephalin and its role in binding and activating delta (DOP) and mu (MOP) opioid receptors
Authors: Bella Ndong Dominique , Blais Véronique , Holleran Brian J. , Proteau‐Gagné Arnaud , Cantin‐Savoie Isabelle , Robert William , Nadon Jean‐François , Beauchemin Sophie , Leduc Richard , Piñeyro Graciela , Guérin Brigitte , Gendron Louis , Dory Yves L. 
Published: April 2018

AbstractEnkephalins are pentapeptidic endogenous ligands that regulate nociception by binding to mu (MOP) and delta (DOP) opioid receptors. To further explore the role of the leucine residue of Leu‐enkephalin, 12 peptidomimetic analogs were synthesized by systematically replacing this residue with non‐natural amino acids. The analogs were tested for their ability to bind DOP and MOP. We also investigated the potency of these analogs to inhibit cAMP production and to recruit β‐arrestin 2 via both receptors. We found that replacement of the leucine residue by substituted non‐natural amino acid derivatives of alanine, cycloleucine, or isoleucine was generally well tolerated. By contrast, substituting leucine with homoproline greatly reduced the affinity for DOP and, to a lesser extent, for MOP. Interestingly, when compared to Leu‐enkephalin, analogs containing either aza‐β‐homoleucine or cycloleucine showed a bias toward inhibition of cAMP production through the activation of DOP but not MOP. By contrast, derivatives containing 4,5‐dehydroleucine or d‐allo‐isoleucine conferred a bias toward β‐arrestin 2 at MOP, but not DOP. Our results suggest that position 5 in Leu‐enkephalin analogs can be further exploited to develop compounds with the potential to produce bias toward G protein or β‐arrestin 2.
Silyl‐functionalized polyolefins via co‐polymerization of vinylsilanes with ethylene or propylene catalyzed by group IV metallocene complexes
Authors: Fu Peng‐Fei , Yang Shengtian 
Published: April 2018

ABSTRACTVinylsilanes CH2CHSiR3 (R = Me, NMe2, OMe, OTMS) copolymerize with ethylene rapidly in the presence of catalytic amounts of [Cp′2ZrMe][MeB(C6F5)3] (Cp′ = η5‐C5Me5) (I) to give high molecular weight silyl‐functionalized polyethylene. The molecular weight of the polymer can be controlled by varying the comonomer concentration as well as the reaction temperature. Relatively low molecular weight polymer was produced at a higher silyl monomer concentration and a higher polymerization temperature. The incorporation of silyl monomer in the polymer is in the range of 0.1‐ 6.0%. On the other hands, catalysts [Cp2ZrMe][MeB(C6F5)3] (Cp′ = η5‐C5H5) (II) and [Cp″2ZrMe][MeB(C6F5)3] (Cp″ = η5‐1,2‐C5Me2H3) (III) show much lower activity. With the use of more coordinatively unsaturated constrained geometry catalysts (CGC), Me2Si(η5‐C5Me4)(NtBu)MMe][MeB(C6F5)3] (IV, M = Zr; V, M = Ti), the silyl monomer incorporation in the polymer was increased to 40%. The Ti catalyst is more active and produces polymer with a higher molecular weight with a higher silyl monomer incorporation at 23 °C. The copolymerization of vinyltrimethylsilane with propylene was also investigated with these catalysts, yielding high silyl‐functionalized propylene copolymer/oligmer. The microstructure of the copolymers/oligomers has been thoroughly investigated by 1D and 2D NMR techniques (1H, 13C, NOE, DEPT, HETCOR, and FLOCK). The results show that the backbone of the copolymers/oligomers is essentially random. Several termination pathways have been identified. In particular, two unsaturated silyl terminations, cis and/or trans‐TMSCHCH, were identified with the constrained geometry catalysts. Their formation was rationalized based on transition state models. It was found that occasional 1,2‐insertion of either propylene or vinyltrimethylsilane into the chain propagation process has a high probability serving as the trigger for polymer chain termination via β‐H elimination. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1308–1321
Characteristics and self‐assembly behaviors of photochromic triblock azo‐copolymers based on hard‐soft‐hard segments synthesized via RAFT process
Authors: Zenati Athmen , Thammalangsy Soulighothai 
Published: April 2018

ABSTRACTA novel series of hard‐soft‐hard triblock azo‐copolymers (TBCs) composed of poly(2‐[2‐(4‐cyano‐azobenzene‐4‐oxy)ethylene‐oxy]ethyl methacrylate) (PCEAMA), poly(methyl methacrylate) (PMMA) and poly(p‐dodecylphenyl‐N‐acrylamide) (PDOPAM) were synthesized by employing reversible addition‐fragmentation chain transfer polymerization. Chemical structures and molecular weights were characterized by 1H nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). Thermal behavior, mesophase, photochemistry and morphology were investigated using differential scanning calorimetry (DSC), optical polarizing microscopy (OPM), ultraviolet–visible spectrophotometry (UV–vis), atomic force microscopy (AFM) and grazing‐incidence small‐angle X‐ray scattering (GISAXS). Kinetic studies confirmed characteristic of controlled/living radical polymerization with low polydispersities (≤1.40). TBCs manifested both endothermic and exothermic transition peaks assigned to smectic to nematic, nematic to smectic, and smectic‐A to smectic‐C phases. TBCs having hight azo fractions of 39 and 34 wt % revealed textures of smectic phase whereas TBC possessing 30 wt % of azo content exhibited poor texture, suggesting nematic phase. Regarding TBC with low azo ratio (25 wt %), neither mesophase texture was found. All TBCs showed photoresponsive behavior under UV–vis irradiation or thermal relaxation. TBC‐1 with PCAEMA (39 wt %), PMMA (40 wt %) and PDOPAM (21 wt %) generated a mixture of cylinder and lamellar nanostructures compared to TBC‐2 and TBC‐3 which formed lamellae. However, TBC‐4 having the highest PDOPAM fraction (50 wt %) produced hexagonal cylindrical nanostructure. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1617–1629
Frequent border‐crossing children and cultural membership
Authors: Chiu Tuen Yi , Choi Susanne Y.P. 
Published: April 2018

AbstractMigration studies typically conceptualise children as either “stayers” or “movers.” However, such binary conceptualisation is at odds with the experiences of children who cross borders frequently. Using the case of children with Hong Kong right of abode who live in southern China but commute daily to Hong Kong to pursue education, this paper examines the structural and family factors leading to this form of frequent border crossing and identifies 4 major strategies that mothers of these children use to help them overcome the barriers to acculturation. These strategies underscore the salience of the rhetoric of cultural membership as symbolic boundaries that delegitimise claims to citizenship of the perceived outsiders and the situated agency of parents in maximising the life chances of their children by helping them permeate the rigid symbolic boundary, and overcome identity ambivalence associated with their simultaneous existence in 2 politically and socially divided territories.
Tunable Spectrum Selectivity for Multiphoton Absorption with Enhanced Visible Light Trapping in ZnO Nanorods
Authors: Tan Kok Hong , Lim Fang Sheng , Toh Alfred Zhen Yang , Zheng Xia‐Xi , Dee Chang Fu , Majlis Burhanuddin Yeop , Chai Siang‐Piao , Chang Wei Sea 
Published: April 2018

AbstractObservation of visible light trapping in zinc oxide (ZnO) nanorods (NRs) correlated to the optical and photoelectrochemical properties is reported. In this study, ZnO NR diameter and c‐axis length respond primarily at two different regions, UV and visible light, respectively. ZnO NR diameter exhibits UV absorption where large ZnO NR diameter area increases light absorption ability leading to high efficient electron–hole pair separation. On the other hand, ZnO NR c‐axis length has a dominant effect in visible light resulting from a multiphoton absorption mechanism due to light reflection and trapping behavior in the free space between adjacent ZnO NRs. Furthermore, oxygen vacancies and defects in ZnO NRs are associated with the broad visible emission band of different energy levels also highlighting the possibility of the multiphoton absorption mechanism. It is demonstrated that the minimum average of ZnO NR c‐axis length must satisfy the linear regression model of Z
p,min = 6.31d to initiate the multiphoton absorption mechanism under visible light. This work indicates the broadening of absorption spectrum from UV to visible light region by incorporating a controllable diameter and c‐axis length on vertically aligned ZnO NRs, which is important in optimizing the design and functionality of electronic devices based on light absorption mechanism.
Scaling Effect on Silicon Nitride Memristor with Highly Doped Si Substrate
Authors: Kim Sungjun , Jung Sunghun , Kim Min‐Hwi , Chen Ying‐Chen , Chang Yao‐Feng , Ryoo Kyung‐Chang , Cho Seongjae , Lee Jong‐Ho , Park Byung‐Gook 
Published: April 2018

AbstractA feasible approach is reported to reduce the switching current and increase the nonlinearity in a complementary metal–oxide–semiconductor (CMOS)‐compatible Ti/SiNx/p+‐Si memristor by simply reducing the cell size down to sub‐100 nm. Even though the switching voltages gradually increase with decreasing device size, the reset current is reduced because of the reduced current overshoot effect. The scaled devices (sub‐100 nm) exhibit gradual reset switching driven by the electric field, whereas that of the large devices (≥1 µm) is driven by Joule heating. For the scaled cell (60 nm), the current levels are tunable by adjusting the reset stop voltage for multilevel cells. It is revealed that the nonlinearity in the low‐resistance state is attributed to Fowler–Nordheim tunneling dominating in the high‐voltage regime (≥1 V) for the scaled cells. The experimental findings demonstrate that the scaled metal–nitride–silicon memristor device paves the way to realize CMOS‐compatible high‐density crosspoint array applications.
Mechanically Assisted Self‐Healing of Ultrathin Gold Nanowires
Authors: Wang Binjun , Han Ying , Xu Shang , Qiu Lu , Ding Feng , Lou Jun , Lu Yang 
Published: April 2018

AbstractAs the critical feature sizes of integrated circuits approaching sub‐10 nm, ultrathin gold nanowires (diameter <10 nm) have emerged as one of the most promising candidates for next‐generation interconnects in nanoelectronics. Also due to their ultrasmall dimensions, however, the structures and morphologies of ultrathin gold nanowires are more prone to be damaged during practical services, for example, Rayleigh instability can significantly alter their morphologies upon Joule heating, hindering their applications as interconnects. Here, it is shown that upon mechanical perturbations, predamaged, nonuniform ultrathin gold nanowires can quickly recover into uniform diameters and restore their smooth surfaces, via a simple mechanically assisted self‐healing process. By examining the local self‐healing process through in situ high‐resolution transmission electron microscopy, the underlying mechanism is believed to be associated with surface atomic diffusion as evidenced by molecular dynamics simulations. In addition, mechanical manipulation can assist the atoms to overcome the diffusion barriers, as suggested by ab initio calculations, to activate more surface adatoms to diffuse and consequently speed up the self‐healing process. This result can provide a facile method to repair ultrathin metallic nanowires directly in functional devices, and quickly restore their microstructures and morphologies by simple global mechanical perturbations.
Combining Multiplex SERS Nanovectors and Multivariate Analysis for In Situ Profiling of Circulating Tumor Cell Phenotype Using a Microfluidic Chip
Authors: Zhang Yizhi , Wang Zhuyuan , Wu Lei , Zong Shenfei , Yun Binfeng , Cui Yiping 
Published: April 2018

AbstractIsolating and in situ profiling the heterogeneous molecular phenotype of circulating tumor cells are of great significance for clinical cancer diagnosis and personalized therapy. Herein, an on‐chip strategy is proposed that combines size‐based microfluidic cell isolation with multiple spectrally orthogonal surface‐enhanced Raman spectroscopy (SERS) analysis for in situ profiling of cell membrane proteins and identification of cancer subpopulations. With the developed microfluidic chip, tumor cells are sieved from blood on the basis of size discrepancy. To enable multiplex phenotypic analysis, three kinds of spectrally orthogonal SERS aptamer nanovectors are designed, providing individual cells with composite spectral signatures in accordance with surface protein expression. Next, to statistically demultiplex the complex SERS signature and profile the cellular proteomic phenotype, a revised classic least square algorithm is employed to obtain the 3D phenotypic information at single‐cell resolution. Combined with categorization algorithm partial least square discriminate analysis, cells from different human breast cancer subtypes can be reliably classified with high sensitivity and selectivity. The results demonstrate that this platform can identify cancer subtypes with the spectral information correlated to the clinically relevant surface receptors, which holds great potential for clinical cancer diagnosis and precision medicine.
Simplified Perovskite Solar Cell with 4.1% Efficiency Employing Inorganic CsPbBr3 as Light Absorber
Authors: Duan Jialong , Zhao Yuanyuan , He Benlin , Tang Qunwei 
Published: April 2018

AbstractPerovskite solar cells with cost‐effectiveness, high power conversion efficiency, and improved stability are promising solutions to the energy crisis and environmental pollution. However, a wide‐bandgap inorganic–semiconductor electron‐transporting layer such as TiO2 can harvest ultraviolet light to photodegrade perovskite halides, and the high cost of a state‐of‐the‐art hole‐transporting layer is an economic burden for commercialization. Here, the building of a simplified cesium lead bromide (CsPbBr3) perovskite solar cell with fluorine‐doped tin oxide (FTO)/CsPbBr3/carbon architecture by a multistep solution‐processed deposition technology is demonstrated, achieving an efficiency as high as 4.1% and improved stability upon interfacial modification by graphene quantum dots and CsPbBrI2 quantum dots. This work provides new opportunities of building next‐generation solar cells with significantly simplified processes and reduced production costs.
Synergistic Targeting and Efficient Photodynamic Therapy Based on Graphene Oxide Quantum Dot‐Upconversion Nanocrystal Hybrid Nanoparticles
Authors: Liu Yan , Xu Yawen , Geng Xiangshuai , Huo Yingying , Chen Dexin , Sun Kang , Zhou Guangdong , Chen Biqiong , Tao Ke 
Published: April 2018

AbstractLocating nanotherapeutics at the active sites, especially in the subcellular scale, is of great importance for nanoparticle‐based photodynamic therapy (PDT) and other nanotherapies. However, subcellular targeting agents are generally nonspecific, despite the fact that the accumulation of a nanoformulation at active organelles leads to better therapeutic efficacy. A PDT nanoformulation is herein designed by using graphene oxide quantum dots (GOQDs) with rich functional groups as both the supporter for dual targeting modification and the photosensitizer for generating reactive oxygen species, and upconversion nanoparticles (UCNs) as the transducer of excitation light. A tumor‐targeting agent, folic acid, and a mitochondrion‐targeting moiety, carboxybutyl triphenylphosphonium, are simultaneously attached onto the UCNs–GOQDs hybrid nanoparticles by surface modification, and a synergistic targeting effect is obtained for these nanoparticles according to both in vitro and in vivo experiments. More significant cell death and a higher extent of mitochondrion damage are observed compared to the results of UCNs–GOQDs nanoparticles with no or just one targeting moiety. Furthermore, the PDT efficacy on tumor‐bearing mice is also effectively improved. Overall, the current work presents a synergistic strategy to enhance subcellular targeting and the PDT efficacy for cancer therapy, which may also shed light on other kinds of nanotherapies.
Charge‐Trap Memory Based on Hybrid 0D Quantum Dot–2D WSe2 Structure
Authors: Hou Xiang , Zhang Heng , Liu Chunsen , Ding Shijin , Bao Wenzhong , Zhang David Wei , Zhou Peng 
Published: April 2018

AbstractRecently, layered ultrathin 2D semiconductors, such as MoS2 and WSe2 are widely studied in nonvolatile memories because of their excellent electronic properties. Additionally, discrete 0D metallic nanocrystals and quantum dots (QDs) are considered to be outstanding charge‐trap materials. Here, a charge‐trap memory device based on a hybrid 0D CdSe QD–2D WSe2 structure is demonstrated. Specifically, ultrathin WSe2 is employed as the channel of the memory, and the QDs serve as the charge‐trap layer. This device shows a large memory window exceeding 18 V, a high erase/program current ratio (reaching up to 104), four‐level data storage ability, stable retention property, and high endurance of more than 400 cycles. Moreover, comparative experiments are carried out to prove that the charges are trapped by the QDs embedded in the Al2O3. The combination of 2D semiconductors with 0D QDs opens up a novelty field of charge‐trap memory devices.
A White Light‐Emitting Quantum Dot Complex for Single Particle Level Interaction with Dopamine Leading to Changes in Color and Blinking Profile
Authors: Pramanik Sabyasachi , Bhandari Satyapriya , Pan Uday Narayan , Roy Shilaj , Chattopadhyay Arun 
Published: April 2018

AbstractThe interaction of the neurotransmitter dopamine is reported with a single particle white light‐emitting (WLE) quantum dot complex (QDC). The QDC is composed of yellow emitting ZnO quantum dots (Qdots) and blue emitting Zn(MSA)2 complex (MSA = N‐methylsalicylaldimine) synthesized on their surfaces. Sensing is achieved by the combined changes in the visual luminescence color from white to blue, chromaticity color coordinates from (0.31, 0.33) to (0.24, 0.23) and the ratio of the exponents (αon/αoff) of on/off probability distribution (from 0.24 to 3.21) in the blinking statistics of WLE QDC. The selectivity of dopamine toward ZnO Qdots, present in WLE QDC, helps detect ≈13 dopamine molecules per Qdot. Additionally, the WLE QDC exhibits high sensitivity, with a limit of detection of 3.3 × 10−9m (in the linear range of 1–100 × 10−9m) and high selectivity in presence of interfering biological species. Moreover, the single particle on–off bilking statistics based detection strategy may provide an innovative way for ultrasensitive detection of analytes.
Defect‐Free, Highly Uniform Washable Transparent Electrodes Induced by Selective Light Irradiation
Authors: Zhong Zhaoyang , Woo Kyoohee , Kim Inhyuk , Kim Hyuntae , Ko Pyeongsam , Kang Dongwoo , Kwon Sin , Kim Hyunchang , Youn Hongseok , Moon Jooho 
Published: April 2018

AbstractA simple route to fabricate defect‐free Ag‐nanoparticle–carbon‐nanotube composite‐based high‐resolution mesh flexible transparent conducting electrodes (FTCEs) is explored. In the selective photonic sintering‐based patterning process, a highly soft rubber or thin plastic substrate is utilized to achieve close and uniform contact between the composite layer and photomask, with which uniform light irradiation can be obtained with diminished light diffraction. This well‐controlled process results in developing a fine and uniform mesh pattern (≈12 μm). The mesh patternability is confirmed to be dependent on heat distribution in the selectively light‐irradiated film and the pattern design for FTCE could be adopted for more precise patterns with desired performance. Moreover, using a very thin substrate could allow the mesh to be positioned closer to the strain‐free neutral mechanical plane. Due to strong interfacial adhesion between the mesh pattern and substrate, the mesh FTCE could tolerate severe mechanical deformation without performance degradation. It is demonstrated that a transparent heater with fine mesh patterns on thin substrate can maintain stability after 100 repeated washing test cycles in which a variety of stress situations occurring in combination. The presented highly durable FTCE and simple fabrication processes may be widely adoptable for various flexible, large‐area, and wearable optoelectronic devices.