bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal evaporation cycle in oxbow lakes formed along the Tisza River in Hungary for flood control
Authors: Babka Beáta , Futó István , Szabó Szilárd
Published: May 2018

As a result of water regulation, dykes (i.e., embankments against floods) were constructed along the Tisza River and meanders were cut to control the floods in the region. These cut‐off meanders resulted in oxbow lakes that are important locations for nature conservation. We collected water samples over 5 years in 7 campaigns to measure the δ18O (‰) and δ2H (‰) ratios in 45 oxbow lakes from the Upper Tisza Region (NE‐Hungary). We applied Random Forest Regression involving climatic data to reveal the connection with the stable isotopes. We determined that isotope ratios changed as a function of time, due to evaporation and a varying water supply (precipitation and groundwater). The average difference in the isotopic ratios for the river and oxbows increased from spring to winter, but decreased between the oxbows on both sides of the dyke. We found that isotope ratios were determined by the maximum monthly temperature in the case of oxbows in the active floodplain, whereas in case of oxbows on the reclaimed side, this was also influenced by the maximum monthly temperature, and the cumulative evaporation. As direct measurement of evaporation is difficult to evaluate, stable isotope measurements provided an effective quantitative alternative to estimate evaporation. Measuring the seasonality of the δ18O and δ2H is important to interpret the results and these data are useful to water management experts to identify the lakes at risk of running dry.
Epigenetic loss of heparan sulfate 3‐O‐sulfation sensitizes ovarian carcinoma to oncogenic signals and predicts prognosis
Authors: Huang Rui‐Lan , Chen Hsiang‐Ju , Chen Lin‐Yu , Chao Tai‐Kuang , Lin Wei‐Yu , Liew Phui‐Ly , Su Po‐Hsuan , Weng Yu‐Chun , Wang Yu‐Chi , Liao Chi‐Chun , Hsu Yaw‐Wen , Wang Hui‐Chen , Lai Hung‐Cheng
Published: May 2018

Precision medicine requires markers for therapeutic guidance. The purpose of this study was to determine whether epithelial ovarian cancer (EOC) epigenetics can lead to the identification of biomarkers for precision medicine. Through integrative methylomics, we discovered and validated the epigenetic signature of NEFH and HS3ST2 as an independent prognostic factor for type II EOC in our dataset (n = 84), and two independent methylomics datasets (total n = 467). Integrated transcriptomics dataset (n = 1147) and tissue microarrays (n = 54) of HS3ST2 also related to high‐methylation statuses and the EOC prognosis. Mechanistic explorations of HS3ST2 have assessed responses to oncogenic stimulations such as IL‐6, EGF, and FGF2 in cancer cells. The combination of HS3ST2 and various oncogenic ligands also confers the worse outcome. 3‐O‐sulfation of heparan sulfate by HS3ST2 makes ovarian cancer cells intrinsically sensitive to oncogenic signals, which sheds new light on the application of HS3ST2 as a companion diagnostic for targeted therapy using kinase inhibitors or therapeutic antibodies.
Experimental and computational studies on a new mixed ligand oxido–rhenium(V) compound
Authors: Saha Pinki , Naskar Jnan Prakash , Majumder Smita , Saha Baptu , Ganguly Rakesh , Bhattacharya Arnab , Chowdhury Shubhamoy
Published: May 2018

A mixed ligand oxido–rhenium(V) complex, [ReOS3(HL)]Cl.H2O (1pCl.H2O), with 3‐thiopentane‐1,5‐dithiolato (S3) as a tridentate ligand and imidazolidinethione (HL) as an ancillary monodentate sulfur donor co‐ligand, has been synthesized. 1pCl.H2O has been characterized by spectral analyses. The X‐ray crystal structure of 1pCl.H2O shows that the complex contains a distorted square‐pyramidal “ReOS4” core. The structural parameters agree with our optimized structure of 1p+. Subsequently, the optimized structure was used to calculate systematically the relative stabilities of a sequence of oxido–Re(V) and the analogous oxido–Tc(V) complexes just by varying the donor sites (N, S, and O) on the tridentate ligand moiety in 1p+. Electrochemical studies on 1pCl.H2O show an oxidative rhenium(VI)/ rhenium(V) couple at 1.561 V versus Ag/AgCl under controlled linear diffusion situation. Vibrational frequencies, electronic structures, and redox potential of 1p+ have been calculated theoretically employing density functional theory (DFT) or time‐dependent‐DFT methods. The experimental findings are in excellent agreement with the computed results. The calculated redox potentials of the investigated oxido–Re(V) complexes and their oxido–Tc(V) counterparts are shown to correlate linearly with their respective chemical potential values.
Association between the XPG gene rs2094258 polymorphism and risk of gastric cancer
Authors: Zhang Zhe , Yin Jiefeng , Xu Qi , Shi Jianfeng
Published: May 2018

Background

Xeroderma pigmentosum group G (XPG) plays an important role in maintaining the stability and integrity of genomic DNA. Previous studies demonstrate some XPG gene polymorphisms are associated with susceptibility to gastric cancer (GC).

Methods

The association between XPG rs2094258 polymorphism and GC risk was investigated first by a hospital‐based case‐control study involving 386 patients and 439 controls and then by a meta‐analysis. The polymorphism was genotyped by polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLR).

Results

Xeroderma pigmentosum group G rs2094258 polymorphism was associated with an increased risk of GC in a Chinese population. The meta‐analysis did not reveal any significant difference in the overall population. Subgroup analysis of geographic locations showed a significant association between the XPG gene rs2094258 polymorphism and GC risk in Southern China. Stratification analysis further indicated significant associations in hospital‐based studies and studies using PCR‐RFLR.

Conclusion

Xeroderma pigmentosum group G gene rs2094258 polymorphism may be associated with an increased risk of GC in Southern China. Nevertheless, the findings of this meta‐analysis should be validated by well‐designed large‐scale case‐control studies among other ethnicities.
Influence of 6 genetic variants on the efficacy of statins in patients with dyslipidemia
Authors: Cano‐Corres Ruth , Candás‐Estébanez Beatriz , Padró‐Miquel Ariadna , Fanlo‐Maresma Marta , Pintó Xavier , Alía‐Ramos Pedro
Published: May 2018

Background

Patients with dyslipidemia are often treated with statins to reduce lipids and hence cardiovascular risk, but treatment response is variable, partly due to genetic factors.

Methods

We studied the influence of 6 gene variants (APOE c.526C > T (APOE2), APOE c.388T > C (APOE4), SLCO1B1 c.521T > C, CYP3A4 c.‐392G > A, HMGCR c.1564‐106A > G, and LPA c.3947 + 467T > C) on statin efficacy assessing 2 indicators: the percent reduction in total cholesterol (TC) and non‐HDL cholesterol (non‐HDL), as well as the achievement of therapeutic goals. The study was performed in a group of patients (n = 100) without previous pharmacological treatment. Multiple regression models were used to calculate the percentage of explanation in response variability added by every variant to a basal model constructed with significant nongenetic control variables.

Results

The most influential variant was HMGCR c.1564‐106A > G (rs3846662), and carriers showed a significantly lower reduction in TC and non‐HDL. This variant is related to an alternative splicing involving exon 13, which is also regulated by lipid concentrations in patients without the variant. Concerning therapeutic goals, HMGCR c.1564‐106A > G hindered the achievement of TC targets on patients.

Conclusions

The HMGCR c.1564‐106A > G variant was associated with less statin efficacy to decrease cholesterol.
Dim artificial light at night affects mating, reproductive output, and reactive oxygen species in Drosophila melanogaster
Authors: McLay Lucy Katherine , Nagarajan‐Radha Venkatesh , Green Mark Philip , Jones Therésa Melanie
Published: May 2018

Humans are lighting the night‐time environment with ever increasing extent and intensity, resulting in a variety of negative ecological effects in individuals and populations. Effects of light at night on reproductive fitness traits are demonstrated across taxa however, the mechanisms underlying these effects are largely untested. One possible mechanism is that light at night may result in perturbed reactive oxygen species (ROS) and oxidative stress levels. Here, we reared Drosophila melanogaster under either dim (10 lx) light or no light (0 lx) at night for three generations and then compared mating and lifetime oviposition patterns. In a second experiment, we explored whether exposure to light at night treatments resulted in variation in ROS levels in the heads and ovaries of six, 23‐ and 36‐day‐old females. We demonstrate that dim light at night affects mating and reproductive output: 10 lx flies courted for longer prior to mating, and female oviposition patterns differed to 0 lx females. ROS levels were lower in the ovaries but not heads, of 10 lx compared with 0 lx females. We suggest that reduced ROS levels may reflect changes in ovarian physiology and cell signaling, which may be related to the differences observed in oviposition patterns. Taken together, our results indicate negative consequences for invertebrates under more stressful, urban, lit conditions and further investigation into the mechanisms driving these changes is warranted to manage invertebrate communities in a brighter future.
Bandwidth enhancement of rectangular microstrip antenna with a rectangular slot by using a novel hybrid optimization method based on the ABC and DE algorithms
Authors: Akdagli Ali , Ustun Deniz
Published: May 2018

In this study, the bandwidth of the rectangular microstrip antenna is improved by using a new integrated technique consisting of a novel hybrid optimization algorithm (HOA) and HyperLynx® 3D electromagnetic platform based on the method of moments (MoM). The novel HOA is developed by integrating the powerful mutation and crossover strategies of the differential evolution algorithm with onlooker bee stage of the artificial bee colony algorithm. The main objective of the design is to enhance bandwidth of the rectangular microstrip antenna by the etching rectangular slot on the antenna ground plane. The optimal position and sizes of the slot are determined by using the integrated optimization technique. The simulation and measurement results indicated a high improvement in the bandwidth of the rectangular microstrip antenna over 45% by using the proposed slot etching method on the ground plane. Additionally, in order to evaluate performance of the HOA, eight benchmark functions having multi or unimodal characteristics were used. The experimental results show that the performance of the HOA was better than both artificial bee colony and differential evolution algorithms.
Impact of poxB, pta, and ackA genes on mineral‐weathering of Enterobacter cloacae S71
Authors: Wang Qi , Zhang Zhendong , Zhu Ying , He Linyan , Sheng Xiafang
Published: May 2018

In this study, biotite weathering behaviors were compared between mineral‐weathering bacteria Enterobacter cloacae S71, mutant strains created by the deletion of poxB, pta, and ackA genes involved in acetate formation, and their complemented strains. Compared to strain S71, a decrease in bacterial growth was observed during the early and middle stages for the mutant ΔpoxB and at the middle and later stages for the mutants Δpta and ΔackA. Dissolved Al and Fe concentrations were lower during the early stage for strain ΔpoxB, at the early or middle stage for strain Δpta, and at the middle and later stages and throughout the weathering process for strain ΔackA, compared to strain S71. Acetate production was depressed during the early stage for strain ΔpoxB, at the early and middle stages for strain Δpta, and throughout the weathering process for strain ΔackA. Overall, the ackA gene exhibited a larger impact on dissolved Fe and acetate concentrations than both the poxB and pta genes. Reduced bacterial growth and lower dissolved Al, Fe, and acetate concentrations recovered by the complemented strains. These results show that strain S71 promoted mineral weathering through the production of acetic acid with distinctive impacts by the genes involved in acetate.
Are Speedy Brains Needed when Divergent Thinking is Speeded—or Unspeeded?
Authors: Forthmann Boris , Lips Corinna , Szardenings Carsten , Scharfen Jana , Holling Heinz
Published: May 2018

In this study, we focus on mental speed and divergent thinking, examining their relationship and the influence of task speededness. Participants (N = 109) completed a set of processing speed tasks and a test battery measuring divergent thinking. We used two speeded divergent‐thinking tasks of 2 minutes and two unspeeded tasks of 8 minutes to test the influence of task speededness on creative quality and their relation to mental speed. Before each task, participants were instructed to be creative in order to optimally measure creative quality. We found a large main effect of task speededness: less creative ideas were generated when tasks were speeded as compared to unspeeded (Cohen's d = −1.64). We could also replicate a positive relationship of mental speed with speeded divergent thinking (r = .21) and mental speed with unspeeded divergent thinking (r = .25). Our hypothesis that the relation is higher for the speeded divergent‐thinking tasks was not confirmed. Importantly, variation in creative quality scores under speeded conditions was not explained by mental speed beyond the predictive power of unspeeded creative quality. The latter finding implies that measurement of creative quality under speeded conditions is not confounded by mental speed.
Endovascular repair of aortic arch intramural hematoma and penetrating ulcers with 810 nm in situ laser‐assisted fenestration: Preliminary results of a single‐center
Authors: Liu Guang , Qin Jinbao , Cui Chaoyi , Zhao Zhen , Ye Kaichuang , Shi Huihua , Liu Xiaobing , Yin Minyi , Yang Guanglin , Huang Sheng , Lu Min , Huang Xintian , Jiang Mier , Li Weimin , Lu Xinwu
Published: May 2018

Purpose

The aim of the present study was to report the clinical outcomes of the use of 810 nm in situ laser‐generated fenestration (ISLF) for the treatment of aortic aneurysms (AAs) and intramural hematomas (IMHs) located in the aortic arch.

Study Design and Methods

Between April 2014 and September 2017, 23 patients (15 men, mean age 66.0 years) with AAs (n = 12) or IMHs (n = 11) underwent thoracic endovascular aortic repair (TEVAR) with 810 nm ISLF of the arch. The primary outcomes of the safety assessment were the presence of endoleaks, mortality and morbidity, including adverse in situ fenestration‐related, cardiovascular, and cerebral events.

Results

Technical success was achieved in all cases. Urgent intervention was performed in 15 (65.2%) cases. Left subclavian artery (LSA) ISLF was applied in six patients, LSA and left common carotid artery (LCCA) ISLF in three patients, and total aortic arch vessel ISLF in two patients. One patient suffered minimal stroke after the procedure and recovered without permanent disability to the extremities in 2 weeks. There were no fenestration‐related complications except in one patient with brachial artery access who suffered a hematoma and underwent incision repair at the puncture site. All fenestrations remained patent, and there were no endoleaks during a mean follow‐up of 10.5 ± 5.7 (range: 2–21) months.

Conclusions

Complete or incomplete endovascular arch reconstruction by ISLF in arch diseases (AAs and IMHs) is feasible and reproducible with safe, effective, and favorable primary results and no need for customized endografts. Lasers Surg. Med. 50:837–843, 2018. © 2018 Wiley Periodicals, Inc.
An Enzyme‐Responsive “Turn‐on” Fluorescence Polymeric Superamphiphile as a Potential Visualizable Phosphate Prodrug Delivery Vehicle
Authors: Yang Xi , Shen Shihong , Guo Li , Tan Jidong , Lei Henxin , Wu Jianghan , Zhao Lei , Xiong Tao , Wu Youshen , Cheng Yilong , Zhang Yanfeng
Published: May 2018

The development of inexpensive and highly efficient enzyme‐responsive polymers has significantly contributed to targeted drug delivery systems. Here, a superamphiphile with a capability of fluorescent dissociation sensing is designed. It is constructed with negatively charged adenosine 5′‐triphosphate (ATP) and negatively charged fluorescein diphosphate (FDP), which are used as fluorescence detection, and a cationic diblock copolymer methoxy‐poly(ethylene glycol)113‐b‐poly(2‐dimethyl‐aminoethyl methacrylate)70. Upon addition of calf intestinal alkaline phosphatase, the superamphiphile disintegrates, presumably due to the enzymatic hydrolysis of ATP. This process is accompanied by an increase in the fluorescence emission intensity of fluorescein owing to the hydrolysis of FDP. The in vitro application of the superamphiphile is also proven. Thus, the “turn‐on” fluorescence of the superamphiphile serves as a real‐time module for detection of the disintegration of superamphiphile.
Injectable Hydrogels for Cardiac Tissue Engineering
Authors: Peña Brisa , Laughter Melissa , Jett Susan , Rowland Teisha J. , Taylor Matthew R. G. , Mestroni Luisa , Park Daewon
Published: May 2018

In light of the limited efficacy of current treatments for cardiac regeneration, tissue engineering approaches have been explored for their potential to provide mechanical support to injured cardiac tissues, deliver cardio‐protective molecules, and improve cell‐based therapeutic techniques. Injectable hydrogels are a particularly appealing system as they hold promise as a minimally invasive therapeutic approach. Moreover, injectable acellular alginate‐based hydrogels have been tested clinically in patients with myocardial infarction (MI) and show preservation of the left ventricular (LV) indices and left ventricular ejection fraction (LVEF). This review provides an overview of recent developments that have occurred in the design and engineering of various injectable hydrogel systems for cardiac tissue engineering efforts, including a comparison of natural versus synthetic systems with emphasis on the ideal characteristics for biomimetic cardiac materials.
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

Incorporation 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

Herein, 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

The 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

Among 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

The 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

With 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

Purpose

In 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.

Methods

In 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.

Results

Our 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.

Conclusions

Our 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

Purpose

The purpose of this study is to increase the robustness of MR fingerprinting (MRF) toward subject motion.

Methods

A 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.

Results

For 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.

Conclusions

MORF 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

Purpose

To develop and validate a regularization approach of optimizing B1 insensitivity of the quantitative magnetization transfer (qMT) pool‐size ratio (F).

Methods

An 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).

Results

The 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.

Conclusion

This 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.
Nuclear magnetic resonance (NMR)‐based metabolomics for cancer research
Authors: Ranjan Renuka , Sinha Neeraj
Published: May 2018

Nuclear magnetic resonance (NMR) has emerged as an effective tool in various spheres of biomedical research, amongst which metabolomics is an important method for the study of various types of disease. Metabolomics has proved its stronghold in cancer research by the development of different NMR methods over time for the study of metabolites, thus identifying key players in the aetiology of cancer. A plethora of one‐dimensional and two‐dimensional NMR experiments (in solids, semi‐solids and solution phases) are utilized to obtain metabolic profiles of biofluids, cell extracts and tissue biopsy samples, which can further be subjected to statistical analysis. Any alteration in the assigned metabolite peaks gives an indication of changes in metabolic pathways. These defined changes demonstrate the utility of NMR in the early diagnosis of cancer and provide further measures to combat malignancy and its progression. This review provides a snapshot of the trending NMR techniques and the statistical analysis involved in the metabolomics of diseases, with emphasis on advances in NMR methodology developed for cancer research.
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

This 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

Malignant 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.
Effects of E44 and KH560 modifiers on properties of distillers grains poly(butylene succinate) composites
Authors: Li Chengtao , Wu Ni , Zhang Min , Wei Chunhui , Yan Fei , Wang Zhenghong
Published: May 2018

In this account, the interaction between E44 and KH560 modifiers and poly(butylene succinate)‐distillers grains (PBS/DGs) composite system was studied experimentally and theoretically by means of molecular dynamics simulation. The PBS/DG biodegradable composites were prepared by melt blending the modified DG and PBS, and composting degradation tests were carried out for a period of 75 days. The effect of E44 and KH560 modifiers on the interfacial features, tensile characteristics, thermal stability and degradation properties of PBS/DG composites were examined. The results showed that both χ and Emix significantly decreased in the composite system, indicating that PBS and DG became easier to mix together in presence of E44 and KH560. Also, the interface effect of DG and PBS improved after the modification with KH560. The mechanical properties of the composites remarkably enhanced when DG was treated with 2% KH560. When compared with PBS, the tensile strength and elongation at break were boosted by 23.66 and 33.18%, respectively. After composting degradation for 75 days, the mass loss rate of PBS/DG reached 42.82%, corresponding to 5.90 times higher than that of pure PBS. Overall, the comprehensive properties of the composites improved. POLYM. COMPOS., 40:1499–1509, 2019. © 2018 Society of Plastics Engineers
Enhanced high permittivity and lowed dielectric loss in cellulose–fiber framework polymer microcomposites
Authors: Xiang Lei , Chen Jing , Yang Yuxi , Xie Dongri , Li Yongqiang , Liu Fang , Ma He , Wu Fan , Chen Kai , Wu Haiping , Lan Ping , Yuan Guoliang , Li Shengtao , Zhang Qinghua , Gu Lin , Wang Yiping , Liu Junming , Zhu Jinsong
Published: May 2018

Poly(vinylidene fluoride) and poly(bisphenol A carbonate), are developed to fabricate advanced dielectric polymer microcomposites. After the cellulose–fiber frameworks are incorporated into the matrix, the room temperature permittivity at 1 kHz is increased as large as by almost 109% to reach ∼81, while the dielectric loss at 1 kHz is decreased by 31% at the magnitude of 10−2. The dielectric mechanism is discussed based on a combination mechanism of dipole polarization, interfacial polarization and surface effect. This study demonstrates the beneficial effect of the cellulose–fiber framework on dielectric properties, providing a promising route to achieve high‐performance dielectric materials. POLYM. COMPOS., 40:1526–1535, 2019. © 2018 Society of Plastics Engineers
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

A 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

The 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

Crosslinked 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
Cross‐linking photopolymerization of monoacrylate initiated by benzophenone
Authors: Sanai Yasuyuki , Kagami Shinobu , Kubota Kouzou
Published: May 2018

The chain‐end structure of the photopolymerized acrylate using benzophenone as an initiator was investigated as well as polymerization behavior. Dodecyl acrylate was used as a monomer in this study. Gelation occurred during ultraviolet (UV) irradiation, whereas a cross‐linker was not employed. Conversion‐time profile below gel point gave a linear first‐order plot suggesting that the steady‐state was held throughout polymerization. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra of the resultant polymer indicated that most polymers had an acryloyl group at one of the chain‐ends, while some polymers had an acryloyl group at each chain‐end. The cross‐linking reaction leading to gelation would have been caused by the subsequent copolymerization of the residual monomer with the latter polymer having two acryloyl groups. Dissolved oxygen in the monomer solution influenced the polymer structure giving hydroxyl group at chain‐end. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1545–1553
Hydrogen bond‐reinforced double‐network hydrogels with ultrahigh elastic modulus and shape memory property
Authors: Wang Yan Jie , Li Chen Yu , Wang Zhi Jian , Zhao Yiping , Chen Li , Wu Zi Liang , Zheng Qiang
Published: May 2018

Development of tough hydrogels has greatly expanded their applications as load‐bearing materials. However, the elastic modulus of tough hydrogels is usually lower than 1 MPa. It remains a challenge to design tough hydrogels with high modulus. We report here a series of tough double‐network (DN) hydrogels with ultrahigh elastic modulus (up to 200 MPa) by forming robust hydrogen bonds between the first poly(acrylic acid) network and the second poly(N‐isopropyl acrylamide) network. The dense cooperative hydrogen bonds greatly reduce the segmental mobility and thus improve the rigidity of gel matrix. Owing to the dynamic nature of hydrogen bonds, the modulus of hydrogels is strongly influenced by temperature and pH, affording the gels shape memory property. The strategy by forming robust noncovalent bonds between interpenetrating networks should be applicable to other systems for designing tough and versatile hydrogels with diverse promising applications. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1281–1286