bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication of Reduction‐Responsive Star‐Shaped Amphiphilic Block Copolymers with Click Coupling‐Generated Block Junctions toward Enhanced Therapeutic Efficacy
Authors: Wang Mingqi , Wang Yunfei , Zhao Sijie , Zhang Xiaolong , Wei Hua 
Published: May 2018

AbstractIncorporation of the reducible disulfide links into delivery systems has been repeatedly highlighted to realize, elegantly, the tradeoff between extracellular stability and intracellular high therapeutic efficacy. Of all the reported introducing strategies, esterification, seemingly the most extensively‐adopted one, suffers from relatively low yield, especially for the esterification coupling between two macromolecules, due to the low condensation efficiency. To improve the coupling efficiency, Cu(I)‐catalyzed azide−alkyne cycloaddition (CuAAc) click coupling with high efficiency and high selectivity is used to incorporate disulfide links to the star‐shaped amphiphilic block copolymers in this study. Interestingly, besides such synthetic advantages, the click coupling‐introduced disulfide joints further endow the resulting star‐shaped copolymer‐based nanocarriers with higher therapeutic efficacy than the analogues containing esterification‐generated disulfide links, in terms of better buffering capacity, greater selective drug release in reducing over nonreducing environments, and higher in vitro cytotoxicity. The disclosed effect of introducing strategy of disulfide link on the delivery efficacy of the drug carriers provides new insights into the structure–property relationship of reduction‐sensitive delivery systems, as well as offering new opportunities for the future design and development of intelligent nanocarriers toward enhanced therapeutic efficacy.
Corundum Fillers with Variable Sizes and Shapes for Epoxy Nanocomposites as High‐Performance Chemical Anchoring and Bonding Systems
Authors: Huber Michael Peter , Angarano Marco , Mülhaupt Rolf 
Published: May 2018

AbstractHerein, the influence of corundum filler types and contents on the morphological, thermal, and mechanical properties of epoxy nanocomposites tailored for applications as chemical anchoring and bonding systems is investigated. Up to 65 wt% corundum particles with aspect ratios (AR) varying between 1 and 70, average particle sizes ranging from 500 nm to 48 µm, and nanoplatelet thickness varying from 40 to 300 nm, are uniformly dispersed in amine‐cured epoxy resins. At both 25 and 50 wt% filler content, the properties of corundum/epoxy composites are far superior to those of the corresponding benchmark epoxy composites containing a conventional filler such as cement, talcum, or sand. The incorporation of corundum nanoplatelets with AR of 50, length of 2 µm, and thickness of 40 nm, significantly improves Young's modulus (3.5–9.8 GPa) and fracture toughness KIc (0.83–1.24 MPa of epoxy nanocomposites at the expense of tensile strength (72–49 MPa). The pull‐out values of the corresponding chemical anchoring systems substantially improve with decreasing sub‐micrometer corundum particle sizes and correlate with tensile strength of the corundum/epoxy nanocomposites, but are much less dependent on corundum particle morphologies, filler aspect ratio, and Young's modulus of the corundum/epoxy composite.
Physically Linked PVA/P(AAm‐co‐SMA) Hydrogels: Tough, Fast Recovery, Antifatigue, and Self‐Healing Soft Materials
Authors: Zheng Wen Jiang , Gao Yang , Fan Xiao Xi , Cui Xiao Feng , Zou Wei , Zheng Dan , Yan Jie , Li Bin 
Published: May 2018

AbstractThe application of traditional chemically crosslinked hydrogels is often limited by poor mechanical properties because of their own inhomogeneous network and irreversible crosslinking bonds. Herein, physical interactions are applied to crosslink the interpenetrating network hydrogel, i.e., hydrogen bonding and crystalline domain for polyvinyl alcohol network, and hydrophobic interaction inside micelle for poly (acrylamide‐co‐stearyl methyl acrylate) [P(AAm‐co‐SMA)] network. In this gel network system, reversible energy dissipation mechanism is realized by dissociation and reassociation of weak interactions including hydrogen bonding and hydrophobic interaction inside the micelle. Strong crystalline domains serve as permanent crosslinking interactions to maintain network integrity under large extension. As a result, the synergy of weak and strong interactions leads to tough, antifatigue, fast recovery, and self‐healing properties of the hydrogel. This proposed strategy of achieving versatile hydrogels can broaden the use of hydrogels into load‐bearing applications.
Regulous vector bundles
Authors: Kucharz Wojciech , Zieliński Maciej 
Published: May 2018

AbstractAmong recently introduced new notions in real algebraic geometry is that of regulous functions. Such functions form a foundation for the development of regulous geometry. Several interesting results on regulous varieties and regulous sheaves are already available. In this paper, we define and investigate regulous vector bundles. We establish algebraic and geometric properties of such vector bundles, and identify them with stratified‐algebraic vector bundles. Furthermore, using new results on curve‐rational functions, we characterize regulous vector bundles among families of vector spaces parametrized by an affine regulous variety. We also study relationships between regulous and topological vector bundles.
Novel Theoretical Self‐Consistent Mean‐Field Approach to Describe the Conductivity of Carbon Fiber–Filled Thermoplastics: PART II. Validation by Computer Simulation
Authors: Yang Guanda , Schubert Dirk W. , Qu Muchao , Nilsson Fritjof 
Published: May 2018

AbstractThe electrical conductivity of polymeric fiber composites is generally strongly dependent on the constituent conductivities, the fiber filler fraction, the fiber aspect ratio, and on the orientation of the fibers. Even though electrically conductive polymer composites are emerging materials of high scientific and commercial interest, accurate mathematical models for describing such materials are rare. A very promising mathematical model for predicting the electrical conductivity below the electrical percolation threshold, for both isotropic and anisotropic composites, is however recently published by Schubert. The shortcomings of that study are that the model includes so far only one predicted parameter and that it is not sufficiently validated. In the current study, finite element modeling is used to successfully validate the model of Schubert for isotropic fiber composites and to accurately determine the predicted parameter. These theoretical predictions are finally compared with experimental conductivity data for isotropic carbon fiber/poly(methyl methacrylate) (PMMA) composites with fiber filler fractions in the range 0–12 vol% and fiber aspect ratios from 5 to 30. The model forecasts, without any adjustable parameters, are satisfactory close to the experimental data.
The underlying pathophysiology and therapeutic approaches for osteoporosis
Authors: Awasthi Harshika , Mani Dayanandan , Singh Divya , Gupta Atul 
Published: May 2018

AbstractWith an increase in the ageing population worldwide, the prevalence of osteoporosis increases at an alarming rate in both male and female irrespective of their ethnicity. At present, the currently available therapeutic options are mostly limited to either bone resorptive or bone forming efficacies and both approaches are associated with serious side effects. Despite these options, there is still need for newer therapeutics to treat osteoporosis, which can offer beneficial effects for maintaining balanced dynamics between bone formation and bone resorption, devoid of any side effect. The proper understanding of pathophysiology of the disease is essential for designing or investigating an effective and safe anti‐osteoporotic agent. This review represents a discussion around the molecular targets with their implications in disease progression, available therapeutic options, the emerging targets, and the importance of designing an effective anti‐osteoporotic agent.
Task‐based design of a synthetic‐collimator SPECT system used for small animal imaging
Authors: Lin Alexander , Kupinski Matthew A. , Peterson Todd E. , Shokouhi Sepideh , Johnson Lindsay C. 
Published: May 2018

PurposeIn traditional multipinhole SPECT systems, image multiplexing — the overlapping of pinhole projection images — may occur on the detector, which can inhibit quality image reconstructions due to photon‐origin uncertainty. One proposed system to mitigate the effects of multiplexing is the synthetic‐collimator SPECT system. In this system, two detectors, a silicon detector and a germanium detector, are placed at different distances behind the multipinhole aperture, allowing for image detection to occur at different magnifications and photon energies, resulting in higher overall sensitivity while maintaining high resolution. The unwanted effects of multiplexing are reduced by utilizing the additional data collected from the front silicon detector. However, determining optimal system configurations for a given imaging task requires efficient parsing of the complex parameter space, to understand how pinhole spacings and the two detector distances influence system performance.MethodsIn our simulation studies, we use the ensemble mean‐squared error of the Wiener estimator (EMSEW) as the figure of merit to determine optimum system parameters for the task of estimating the uptake of an 123I‐labeled radiotracer in three different regions of a computer‐generated mouse brain phantom. The segmented phantom map is constructed by using data from the MRM NeAt database and allows for the reduction in dimensionality of the system matrix which improves the computational efficiency of scanning the system's parameter space. To contextualize our results, the Wiener estimator is also compared against a region of interest estimator using maximum‐likelihood reconstructed data.ResultsOur results show that the synthetic‐collimator SPECT system outperforms traditional multipinhole SPECT systems in this estimation task. We also find that image multiplexing plays an important role in the system design of the synthetic‐collimator SPECT system, with optimal germanium detector distances occurring at maxima in the derivative of the percent multiplexing function. Furthermore, we report that improved task performance can be achieved by using an adaptive system design in which the germanium detector distance may vary with projection angle. Finally, in our comparative study, we find that the Wiener estimator outperforms the conventional region of interest estimator.ConclusionsOur work demonstrates how this optimization method has the potential to quickly and efficiently explore vast parameter spaces, providing insight into the behavior of competing factors, which are otherwise very difficult to calculate and study using other existing means.
Image reconstruction algorithm for motion insensitive MR Fingerprinting (MRF): MORF
Authors: Mehta Bhairav Bipin , Ma Dan , Pierre Eric Yann , Jiang Yun , Coppo Simone , Griswold Mark Alan 
Published: May 2018

PurposeThe purpose of this study is to increase the robustness of MR fingerprinting (MRF) toward subject motion.MethodsA novel reconstruction algorithm, MOtion insensitive MRF (MORF), was developed, which uses an iterative reconstruction based retrospective motion correction approach. Each iteration loops through the following steps: pattern recognition, metric based identification of motion corrupted frames, registration based motion estimation, and motion compensated data consistency verification. The proposed algorithm was validated using in vivo 2D brain MRF data with retrospective in‐plane motion introduced at different stages of the acquisition. The validation was performed using qualitative and quantitative comparisons between results from MORF, the iterative multi‐scale (IMS) algorithm, and with the IMS results using data without motion for a ground truth comparison. Additionally, the MORF algorithm was evaluated in prospectively motion corrupted in vivo 2D brain MRF datasets.ResultsFor datasets corrupted by in‐plane motion both prospectively and retrospectively, MORF noticeably reduced motion artifacts compared with iterative multi‐scale and closely resembled the results from data without motion, even when ∼54% of data was motion corrupted during different parts of the acquisition.ConclusionsMORF improves the insensitivity of MRF toward rigid‐body motion occurring during any part of the MRF acquisition.
Sensitivity regularization of the Cramér‐Rao lower bound to minimize B1 nonuniformity effects in quantitative magnetization transfer imaging
Authors: Boudreau Mathieu , Pike G. Bruce 
Published: May 2018

PurposeTo develop and validate a regularization approach of optimizing B1 insensitivity of the quantitative magnetization transfer (qMT) pool‐size ratio (F).MethodsAn expression describing the impact of B1 inaccuracies on qMT fitting parameters was derived using a sensitivity analysis. To simultaneously optimize for robustness against noise and B1 inaccuracies, the optimization condition was defined as the Cramér‐Rao lower bound (CRLB) regularized by the B1‐sensitivity expression for the parameter of interest (F). The qMT protocols were iteratively optimized from an initial search space, with and without B1 regularization. Three 10‐point qMT protocols (Uniform, CRLB, CRLB+B1 regularization) were compared using Monte Carlo simulations for a wide range of conditions (e.g., SNR, B1 inaccuracies, tissues).ResultsThe B1‐regularized CRLB optimization protocol resulted in the best robustness of F against B1 errors, for a wide range of SNR and for both white matter and gray matter tissues. For SNR = 100, this protocol resulted in errors of less than 1% in mean F values for B1 errors ranging between −10 and 20%, the range of B1 values typically observed in vivo in the human head at field strengths of 3 T and less. Both CRLB‐optimized protocols resulted in the lowest σF values for all SNRs and did not increase in the presence of B1 inaccuracies.ConclusionThis work demonstrates a regularized optimization approach for improving the robustness of auxiliary measurements (e.g., B1) sensitivity of qMT parameters, particularly the pool‐size ratio (F). Predicting substantially less B1 sensitivity using protocols optimized with this method, B1 mapping could even be omitted for qMT studies primarily interested in F.
Topology optimization with incompressible materials under small and finite deformations using mixed u/p elements
Authors: Zhang Guodong , Alberdi Ryan , Khandelwal Kapil 
Published: May 2018

SummaryThis paper focuses on topology optimization utilizing incompressible materials under both small‐ and finite‐deformation kinematics. To avoid the volumetric locking that accompanies incompressibility, linear and nonlinear mixed displacement/pressure (u/p) elements are utilized. A number of material interpolation schemes are compared, and a new scheme interpolating both Young's modulus and Poisson's ratio (E‐ν interpolation) is proposed. The efficacy of this proposed scheme is demonstrated on a number of examples under both small‐ and finite‐deformation kinematics. Excessive mesh distortions that may occur under finite deformations are dealt with by extending a linear energy interpolation approach to the nonlinear u/p formulation and utilizing an adaptive update strategy. The proposed optimization framework is demonstrated to be effective through a number of representative examples.
Overexpression of EZH2 in conjunctival melanoma offers a new therapeutic target
Authors: Cao Jinfeng , Pontes Kelly CS , Heijkants Renier C , Brouwer Niels J , Groenewoud Arwin , Jordanova Ekaterina S , Marinkovic Marina , van Duinen Sjoerd , Teunisse Amina FAS , Verdijk Robert M , Snaar‐Jagalska Ewa , Jochemsen Aart G , Jager Martine J 
Published: May 2018

AbstractMalignant melanoma of the conjunctiva (CM) is an uncommon but potentially deadly disorder. Many malignancies show an increased activity of the epigenetic modifier enhancer of zeste homolog 2 (EZH2). We studied whether EZH2 is expressed in CM, and whether it may be a target for therapy in this malignancy. Immunohistochemical analysis showed that EZH2 protein expression was absent in normal conjunctival melanocytes and primary acquired melanosis, while EZH2 was highly expressed in 13 (50%) of 26 primary CM and seven (88%) of eight lymph node metastases. Increased expression was positively associated with tumour thickness (p =0.03). Next, we targeted EZH2 with specific inhibitors (GSK503 and UNC1999) or depleted EZH2 by stable shRNA knockdown in three primary CM cell lines. Both pharmacological and genetic inactivation of EZH2 inhibited cell growth and colony formation and influenced EZH2‐mediated gene transcription and cell cycle profile in vitro. The tumour suppressor gene p21/CDKN1A was especially upregulated in CM cells after EZH2 knockdown in CM cells. Additionally, the potency of GSK503 against CM cells was monitored in zebrafish xenografts. GSK503 profoundly attenuated tumour growth in CM xenografts at a well‐tolerated concentration. Our results indicate that elevated levels of EZH2 are relevant to CM tumourigenesis and progression, and that EZH2 may become a potential therapeutic target for patients with CM. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
Carbon nanotubes and polyaniline filled hybrid epoxy composites: Assessing the viscoelastic behavior and mechanical properties
Authors: Khandelwal Vinay , Sahoo Sushanta K. , Manik Gaurav , Biswas Kishor 
Published: May 2018

In the current work, polyaniline (PANI) and epoxy (EP) composites were prepared and the effect of carbon nanotubes (CNT) addition to EP/PANI (5%) composite on mechanical and viscoelastic properties was studied. PANI was synthesized using p‐toluenesulfonic acid (PTSA) as dopant and characterized through UV–vis and FTIR spectroscopy. Viscosity of uncured EP and composites was studied as a function of shear rate and found to increase with fillers concentration. Dynamic mechanical analysis revealed that PANI increased the storage modulus wherein glass transition temperature (Tg) almost remains constant. Addition of 0.1% CNT to EP/PANI (5%) composite further raised the modulus whereas 0.4% CNT had no significant effect on storage modulus due to agglomeration. However, peak intensity of tan δ curve and Tg were improved for both CNT concentrations. Mechanical properties like tensile, flexural, and impact strength remained unaltered at low PANI (5%) content while at high loading these properties deteriorated significantly. 0.1% CNT has marginal effect on mechanical strength of EP/PANI (5%) system while 0.4% CNT notably reduced the properties. Morphological studies showed that PANI had good dispersion in matrix at lower loading (5%) while it forms uniformly distributed aggregates at higher contents. PANI dispersion was not affected by inclusion of CNT. POLYM. COMPOS., 40:E1143–E1150, 2019. © 2018 Society of Plastics Engineers
Noncovalent functionalization of carbon nanotubes using branched random copolymer for improvement of thermal conductivity and mechanical properties of epoxy thermosets
Authors: Tang Yuyao , Zhao Fangqiao , Fei Xiaoma , Wei Wei , Li Xiaojie , Luo Jing , Zhu Ye , Liu Xiaoya 
Published: May 2018

AbstractA branched random copolymer, poly[(hydroxyethyl acrylate)‐r‐(N‐vinylcarbazole)] (BPHNV), was synthesized through a facile one‐pot free radical polymerization with hydroxyethyl acrylate andN‐vinylcarbazole monomers, using 4‐vinylmethylmercaptan as the chain transfer agent. BPHNV was employed to noncovalently modify multiwall carbon nanotubes (MWCNTs) by π–π interaction. The as‐modified MWCNTs were then incorporated into epoxy resin to improve the thermal conductivity and mechanical properties of epoxy thermosets. The results suggest that, due to both the conjugation structure and the epoxy‐philic component, BPHNV could form a polymer layer on the wall of MWCNTs and inhibit entanglement, helping the uniform dispersion of MWCNTs in epoxy matrix. Owing to the unprecedented thermal conductivity of MWCNTs and the enhancement in the interfacial interaction between fillers and matrix, the thermal conductivity of epoxy/MWCNTs/BPHNV composites increases by 78% at extremely low filler loadings, while the electrical resistivity is still maintained on account of the insulating polymer layer. Meanwhile, the mechanical properties and glass transition temperature (Tg) of the thermosets are elevated effectively, with no significant decrease occurring to the modulus. The addition of as little as 0.1 wt% of MWCNTs decorated with 1.0 wt% of BPHNV to an epoxy matrix affords a great increase of 130% in impact strength for the epoxy thermosets, as well as an increase of over 13 °C inTg. © 2018 Society of Chemical Industry
Challenge and hindrance stress among schoolteachers
Authors: Stiglbauer Barbara , Zuber Julia 
Published: May 2018

AbstractThe challenge–hindrance stress framework argues that certain job stressors have entirely detrimental effects (hindrance stress), but some may also have beneficial effects (challenge stress). Though the challenge–hindrance framework has largely been neglected in teacher stress research, we adopted it to provide a more differentiated view of the most prominent stressors in the teaching profession. We asked a sample of 528 secondary schoolteachers to report the extent to which they perceived occupation‐specific stressors as motivating (challenge stress) and burdening (hindrance stress). Most stressors (those associated with sociopolitical pressure, students’ misbehavior, and lack of resources) were seen as a hindrance rather than a challenge. Only stressors associated with expanded job scope seem to have had more challenge than hindrance potential. Teachers’ hindrance (but not challenge) stress in turn was a strong predictor of psychophysiological symptoms. Importantly, hindrance stress was highest and also the most significant predictor of psychophysiological symptoms if it arose from sociopolitical pressure. In sum, the results indicate that the challenge–hindrance framework might serve as a useful theoretical background in the field of teacher stress research and could offer another explanation for the poor health reported by this occupational group.
Control of cationic nanogel PEGylation in heterogeneous ARGET ATRP emulsion polymerization with PEG macromonomers
Authors: Spencer David S. , Luu Bryan C. , Beckman David W. , Peppas Nicholas A. 
Published: May 2018

ABSTRACTCrosslinked cationic nanoscale networks with hydrophobic cores are an environmentally robust alternative to self‐assembled polymeric drug delivery carriers with respect to therapeutic encapsulation and stability to dilution. However, the ability to tune the degree of PEG incorporated into nanogels during synthesis is more challenging. In this work, biodegradable cationic nanogels were synthesized by ARGET ATRP emulsion polymerization in a single step. The density of PEG in the final nanogels ranged from zero to 40 wt % and was dependent on the feed concentration of PEG monomer, surfactant concentration, surfactant hydrophilic–lipophilic balance, and the ratio of cationic to nonionic surfactant. A comprehensive analysis of nanogel material properties as a function of PEG graft density is presented including analysis of composition, monomer conversion, thermal properties, size, surface charge, and degradation. This study provides a robust analysis for the synthesis of degradable cationic nanogels via a controlled radical polymerization with predictable degrees of PEGylation. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1536–1544