bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of poly(benzimidazole‐amide) nanocomposites by the incorporation of amine‐functionalized ZnO nanoparticles: Thermal and morphological characterization
Authors: Toiserkani Hojjat
Published: March 2018

Fabrication, characterization, and properties of novel poly(benzimidazole‐amide)/functionalized ZnO nanocomposites (PBIA/APS‐ZnO NCs) were investigated. At first, an aromatic PBA containing 3 imidazole units per repeat unit was synthesized by direct polycondensation of 1,3‐bis(5‐carboxylic acid‐2‐benzimidazole)benzene (BCAB) with 5‐(2‐benzimidazole)‐1,3‐phenylenediamine (DAMI) with good yield as a polymeric matrix. The periphery of zinc oxide nanoparticles (ZnO NPs) was modified with 3‐aminopropyltriethoxysilane (APS) to have a better dispersion NPs and enhancing interactions between nanoparticles and PBIA matrix. Different percentages of functionalized NPs (0, 4, 8, and 12 wt.%) were then embedded in PBA matrix through ultrasonic irradiation technique. Fourier transform infrared and thermo‐gravimetric analysis (TGA) confirmed that APS was successfully attached on the ZnO NP surface. The obtained NCs were characterized by means of Fourier transform infrared, X‐ray diffraction, scanning electron microscopy, and TGA. The TGA of the PBIA/APS‐ZnO NCs showed the enhancement in the thermal stability in comparison with the neat PBIA and that this increase is higher when the NP content increases. Scanning electron microscopy analyses of NCs revealed that the dispersion of APS‐ZnO NPs was uniformly done in the PBIA matrix.
Preparation and characterization of hybrid cationic hydroxyethyl cellulose/sodium alginate polyelectrolyte antimicrobial films
Authors: Şen Ferhat , Kahraman Memet Vezir
Published: March 2018

This study aimed to develop polyelectrolyte‐structured antimicrobial food packaging materials that do not contain any antimicrobial agents. Cationic hydroxyethyl cellulose was synthesized and characterized by Fourier‐transform infrared, 1H NMR, and 13C NMR spectroscopy. Its nitrogen content was determined by Kjeldahl method. Polyelectrolyte‐structured antimicrobial food packaging materials were prepared using hydroxyethyl cellulose, cationic hydroxyethyl cellulose, and sodium alginate. Antimicrobial activity of materials was defined by inhibition zone method (disc diffusion method). Thermal stability of samples was evaluated by thermal gravimetric analysis and differential scanning calorimetry. Surface morphology of samples was investigated by SEM. The obtained results prove that produced food packaging materials have good thermal and antimicrobial properties, and they can be used as food packaging material in many industries.
Screening of bioactive components from traditional Chinese medicines using cell membrane chromatography coupled with mass spectrometry
Authors: Han Shengli , Lv Yanni , Wei Fen , Fu Jia , Hu Qi , Wang Sicen
Published: March 2018

Introduction

Cell membrane chromatography (CMC), as a highly selective type of affinity chromatography, has been demonstrated as an effective method to screen bioactive components acting on specific receptor from a complicated biological system.

Objective

To review the recent research progress and the technical applications of these analytical methods using CMC combined with gas chromatography‐mass spectrometry, (GC/MS) and liquid chromatography‐mass spectrometry (LC/MS).

Methodology

In this review, we briefly introduce the CMC offline GC/MS, CMC online GC/MS, CMC offline LC/MS, and CMC online LC/MS system. And the practical application of these technologies is also enumerated. Then the future of these technologies and research methods were discussed.

Results

Many bioactive components interacting with specific receptors have been screened and identified in traditional Chinese medicines.

Conclusion

CMC technique has been combined with GC/MS and HPLC/MS and these combined systems have been successfully used to screen bioactive components acting on specific receptors from a complicated biological system.
A simple and fast quantitative analysis of quinolizidine alkaloids and their biosynthetic precursor, lysine, in Sophora alopecuroides by hydrophilic interaction chromatography coupled with triple‐quadrupole tandem mass spectroscopy
Authors: Wang Hanqing , Xiao Dong , Li Wei , Zhang Xia , Gao Xiaojuan , Yong Jingjiao , Zhao Jianjun , Koike Kazuo
Published: March 2018

Introduction

Different parts of Sophora alopecuroides L. (Fabaceae) have historically been used in traditional Chinese medicine for the treatment of dysentery and enteritis. This plant is also utilised as an important resource for industrial preparation of quinolizidine alkaloidal pharmaceuticals.

Objective

Establish a reliable, simple and fast analytical method for the quantitative determination of the quinolizidine‐type alkaloids and extend understanding of the metabolism of quinolizidine‐type alkaloids in S. alopecuroides.

Methods

Hydrophilic interaction chromatography coupled with triple‐quadrupole tandem mass spectrometry (HILIC‐TQ‐MS/MS) in multiple‐reaction monitoring (MRM) mode were used to determine seven quinolizidine‐type alkaloids and their biosynthetic precursor, lysine, in S. alopecuroides.

Results

A good separation was obtained on an ultra high‐performance liquid chromatography (UHPLC) amide column within 7 min. The overall limits of detection (LODs) were between 1.13 and 2.81 ng/ml, and limits of quantitation (LOQs) were between 3.80 and 8.48 ng/ml. The developed method was successfully applied to 21 samples of S. alopecuroides. The seeds had the highest concentration of alkaloids among the different plant parts. Oxymatrine and oxysophocarpine were the two most abundant alkaloids in all of the different parts and at different phenological growth stages. The contents of quinolizidine alkaloids showed correlations with lysine.

Conclusion

A rapid and sensitive analytical method was established for the simultaneous determination of seven quinolizidine‐type alkaloids and their biosynthetic precursor, lysine, in S. alopecuroides; the content of lysine may be used as a marker to predict alkaloid production.
Anti‐ageing effect of red ginseng revealed by urinary metabonomics using RRLC‐Q‐TOF‐MS
Authors: Sun Jinghui , Jiao Chuanxin , Ma Yue , Chen Jianguang , Wu Wei , Liu Shuying
Published: March 2018

Introduction

Red ginseng (RG) is one of the main processed products of the roots and rhizomes of Panax ginseng C.A. Meyer and is used for anti‐ageing. But how metabonomic influences of RG on the progress of ageing are less researched.

Objective

A metabonomic method was developed to study the characters of the ageing process and the effects of total ginsenosides of red ginseng (TGRG) on the progress of ageing.

Methods

Urine samples from four different ages (4, 12, 18 and 24 months old) of rats and interference after TGRG were analysed by rapid resolution liquid chromatography coupled with quadruple‐time‐of‐flight mass spectrometry (RRLC‐Q‐TOF‐MS) and multivariate statistical analysis were performed for the pattern recognition and characteristic metabolites identification.

Results

Fourteen potential biomarkers were found and identified by MS/MS analysis by referring to authentic chemicals. The analysis of metabolic pathways indicated that the reduced energy and lipid metabolism, the decline of kidney function and amino acids metabolism disorders were the main features of ageing. After TGRG administration, lipid and amino acids metabolism of 18 and 24 month‐old rats were adjusted to restore a younger level, and nine related biomarkers in the ageing process reset to a younger level were recognised.

Conclusion

These changes showed that TGRG may produce an anti‐ageing effect by intervening in the lipid metabolism and correcting the amino acid metabolism disorders in ageing rats.
Clinical application of chromosomal microarray analysis for the prenatal diagnosis of chromosomal abnormalities and copy number variations in fetuses with congenital heart disease
Authors: Xia Yu , Yang Yongchao , Huang Shufang , Wu Yueheng , Li Ping , Zhuang Jian
Published: March 2018

Objectives

This study aimed to determine chromosomal abnormalities and copy number variations (CNVs) in fetuses with congenital heart disease (CHD) by chromosomal microarray analysis (CMA).

Methods

One hundred and ten cases with CHD detected by prenatal echocardiography were enrolled in the study; 27 cases were simple CHDs, and 83 were complex CHDs. Chromosomal microarray analysis was performed on the Affymetrix CytoScan HD platform. All annotated CNVs were validated by quantitative PCR.

Results

Chromosomal microarray analysis identified 6 cases with chromosomal abnormalities, including 2 cases with trisomy 21, 2 cases with trisomy 18, 1 case with trisomy 13, and 1 unusual case of mosaic trisomy 21. Pathogenic CNVs were detected in 15.5% (17/110) of the fetuses with CHDs, including 13 cases with CHD‐associated CNVs. We further identified 10 genes as likely novel CHD candidate genes through gene functional enrichment analysis. We also found that pathogenic CMA results impacted the rate of pregnancy termination.

Conclusions

This study shows that CMA is particularly effective for identifying chromosomal abnormalities and CNVs in fetuses with CHDs as well as having an effect on obstetrical outcomes. The elucidation of the genetic basis of CHDs will continue to expand our understanding of the etiology of CHDs.
Methodological challenges when evaluating potential off‐label prescribing of drugs using electronic health care databases: A case study of dabigatran etexilate in Europe
Authors: Cainzos‐Achirica Miguel , Varas‐Lorenzo Cristina , Pottegård Anton , Asmar Joelle , Plana Estel , Rasmussen Lotte , Bizouard Geoffray , Forns Joan , Hellfritzsch Maja , Zint Kristina , Perez‐Gutthann Susana , Pladevall‐Vila Manel
Published: March 2018

Purpose

To report and discuss estimated prevalence of potential off‐label use and associated methodological challenges using a case study of dabigatran.

Methods

Observational, cross‐sectional study using 3 databases with different types of clinical information available: Cegedim Strategic Data Longitudinal Patient Database (CSD‐LPD), France (cardiologist panel, n = 1706; general practitioner panel, n = 2813; primary care data); National Health Databases, Denmark (n = 28 619; hospital episodes and dispensed ambulatory medications); and Clinical Practice Research Datalink (CPRD), UK (linkable to Hospital Episode Statistics [HES], n = 2150; not linkable, n = 1285; primary care data plus hospital data for HES‐linkable patients). Study period: August 2011 to August 2015. Two definitions were used to estimate potential off‐label use: a broad definition of on‐label prescribing using codes for disease indication (eg, atrial fibrillation [AF]), and a restrictive definition excluding patients with conditions for which dabigatran is not indicated (eg, valvular AF).

Results

Prevalence estimates under the broad definition ranged from 5.7% (CPRD‐HES) to 34.0% (CSD‐LPD) and, under the restrictive definition, from 17.4% (CPRD‐HES) to 44.1% (CSD‐LPD). For the majority of potential off‐label users, no diagnosis potentially related to anticoagulant use was identified. Key methodological challenges were the limited availability of detailed clinical information, likely leading to overestimation of off‐label use, and differences in the information available, which may explain the disparate prevalence estimates across data sources.

Conclusions

Estimates of potential off‐label use should be interpreted cautiously due to limitations in available information. In this context, CPRD HES‐linkable estimates are likely to be the most accurate.
A systematic review of adverse events of rifapentine and isoniazid compared to other treatments for latent tuberculosis infection
Authors: Pease Christopher , Hutton Brian , Yazdi Fatemeh , Wolfe Dianna , Hamel Candyce , Barbeau Pauline , Skidmore Becky , Alvarez Gonzalo G.
Published: March 2018

Purpose

Tuberculosis (TB) remains a common cause of death globally. A regimen of 12 doses of isoniazid (INH) and rifapentine given once weekly (INH/RPT‐3) has recently been recommended by the World Health Organization for the treatment of latent TB infection (LTBI). We aimed to determine whether the INH/RPT‐3 regimen had similar or lesser rates of adverse events compared to other LTBI regimens, namely INH for 9 months, INH for 6 months, rifampin for 3 to 4 months, and rifampin plus INH for 3 to 4 months.

Methods

We searched MEDLINE, Embase, CENTRAL, PubMed, ICTRP, clinicaltrials.gov, and Canadian Agency for Drugs and Technologies in Health's Gray Matters Light for randomized, postmarketing, and comparative nonrandomized studies of patients with confirmed LTBI that reported the frequency of at least 1 adverse event of relevance for a regimen of interest. The search included studies published until March 2017. The frequencies of adverse events were extracted and are presented descriptively.

Results

Data from 23 randomized and 55 nonrandomized studies were included. Although inconsistent event reporting and high heterogeneity limited comparisons, the adverse event profile of INH/RPT‐3 appeared generally favorable. Flu‐like reactions were reported with an increased frequency and hepatotoxicity with a lower frequency than standard treatment.

Conclusions

While INH/RPT‐3 had an overall low frequency of adverse events compared to INH monotherapy, reporting of adverse events for many regimens was limited meaning results should be interpreted cautiously. Future studies of LTBI treatment would benefit from more complete collection and reporting of adverse events and more consistent definitions of hepatotoxicity.
Converting polar cyclic peptides into membrane permeable molecules using N‐methylation
Authors: Lee Leo L. H. , Buckton Laura K. , McAlpine Shelli R.
Published: March 2018

Described are the design, synthesis, and biological evaluation of 5 N‐methylated analogs that are based on a lead drug structure LB51. LB51 is a cyclic pentapeptide that inhibits heat shock protein 90 and although a potent inhibitor of the protein function, it has poor cell permeability. Introduction of an N‐methyl moiety at each amino acid produces 5 analogs of LB51, where all 5 show significantly improved membrane permeability over the lead molecule despite the presence of 4 highly polar side chains.
On the use of acrylated epoxidized soybean oil as a reactive compatibilizer in injection‐molded compostable pieces consisting of polylactide filled with orange peel flour
Authors: Quiles‐Carrillo Luis , Montanes Nestor , Lagaron Jose Maria , Balart Rafael , Torres‐Giner Sergio
Published: March 2018

Novel green composites made of polylactide (PLA) and orange peel flour (OPF) were melt‐compounded using twin‐screw extrusion and shaped into pieces by injection molding. Orange peel, a major by‐product of the juice industry, was first ground to flour and then incorporated as a lignocellulosic filler into the biopolymer at 10, 20 and 30 wt%. Since both components of the green composite presented low compatibility, the resultant injection‐molded pieces showed poor ductility and impaired thermomechanical performance. As a new bio‐based reactive compatibilizer, acrylated epoxidized soybean oil (AESO) was added at five parts per hundred resin to the PLA/OPF formulations during the extrusion process. The addition of AESO increased the filler–biopolymer adhesion and led to compostable green composite pieces with improved physical properties. The enhancement achieved was related to a dual effect of plasticization and melt grafting of the OPF particles onto the PLA chains provided by the multiple acrylate and epoxy groups present in AESO. The use of multi‐functionalized vegetable oils to improve the performance of green composites certainly opens up new opportunities for the expansion of fully bio‐based and biodegradable materials that are partially obtained from agro‐food waste. © 2018 Society of Chemical Industry
Preparation of composites based on recycled polypropylene and automotive shredder residue
Authors: Yang Shuangqiao , Bai Shibing , Duan Wenfeng , Wang Qi
Published: March 2018

In past research, mechanical recycling of automotive shredder residue (ASR) has led to serious deterioration of material performance, and real‐scale application in this way still remains a challenge. Here, we report a sustainable approach called solid‐state shear milling (SSSM) for the production of high‐performance polypropylene (PP)/ASR composites with robust mechanical performance on a commercial scale. After the SSSM process, the obtained 50/50 wt% PP/ASR composite exhibited a 41.3% increase in tensile strength, 32.9% increase in flexural strength and 55.0% increase in impact toughness when compared with corresponding composites made by traditional direct melt blending. In particular, the toughness of the material can be improved by further addition of PP grafted with maleic anhydride with toughness comparable to that of recycled PP, and a 325% increase in toughness can be obtained with addition of styrene–butadiene–styrene block copolymer grafted with maleic anhydride. This PP/ASR composite shows good processability and high thermal stability, and meets the requirements of many applications for nonstructural products. The approach presented in this paper highlights a novel technique for ASR recycling. © 2018 Society of Chemical Industry
Self‐propagating amplification reactions for molecular detection and signal amplification: Advantages, pitfalls, and challenges
Authors: Sun Xiaolong , Shabat Doron , Phillips Scott T. , Anslyn Eric V.
Published: March 2018

Self‐propagating cascade reactions are a recent development for chemosensing protocols. These cascade reactions, in principle, offer low limits of detection by virtue of exponential signal amplification and are initiated by a specific, preplanned molecular detection event. This combination of selectivity for a detection event followed by in situ signal amplification is achieved by exploitation of mechanistic organic chemistry and thus has resulted in various chemosensing protocols that use one or more reagents to achieve the desired selectivity and sensitivity for an assay. Species such as hydrogen peroxide, thiols, and fluoride have been used as active reagents to initiate the first examples of self‐propagating signal amplification reactions, although many other active reagents should be compatible with the approaches. A common feature of the reagents that support the self‐propagating signal amplification reactions is the involvement of quinone methide intermediates resulting from elimination of optical reporters and/or active reagents, where the latter propagates the signal amplification reaction. The early examples of these amplification sequences, however, are slow to reach full signal, thus leaving time for background reactions to generate nonspecific signals. This issue of background has limited practical applications of these self‐propagating signal amplification reactions, as has challenging synthetic routes to the reagents, as well as the potential for other chemical species to interfere with the detection and signal amplification processes. Thus, the goal of this review is to summarize the progress of self‐propagating signal amplification technology, to identify the pitfalls of current designs, and by doing so, to stimulate future studies in this growing and promising research area.
Tetrasubstituted bisadamantylidenes—Highly twisted alkenes
Authors: Bachrach Steven M.
Published: March 2018

A number of 1,3,1′,3′‐tetrasubstituted bisadamantylidenes are examined with 4 different density functional methods (BP86‐D3, ωB97X‐D, B3LYP, and B3LYP‐D3) and the 6‐311G(d) basis set. With increasing steric bulk, these substituted bisadamantylidenes become ever more twisted about the central carbon‐carbon double bond. This manifests in significantly reduced singlet‐triplet gaps from that of typical alkenes, with the tetra‐t‐butylbisadamantylidene 17, twisted to almost 90°, having a gap of only 2.2 kcal mol−1. While its large strain energy may preclude the synthesis of 17, other less‐strained tetrasubstituted analogues are more feasible synthetic targets and still possess small singlet‐triplet gaps, which should be testable by variable temperature NMR and EPR spectroscopy. The twisted alkenes also result in a low rotational energy barrier, and 4 examples with a low barrier to cis‐trans isomerization are presented. These too should be testable by experiment.
Identification of Clostridium difficile Immunoreactive Spore Proteins of the Epidemic Strain R20291
Authors: Pizarro‐Guajardo Marjorie , Ravanal María Cristina , Paez Maria Daniela , Callegari Eduardo , Paredes‐Sabja Daniel
Published: March 2018

Purpose

Clostridium difficile infections are the leading cause of diarrhea associated with the use of antibiotics. During infection, C. difficile initiates a sporulation cycle leading to the persistence of C. difficile spores in the host and disease dissemination. The development of vaccine and passive immunization therapies against C. difficile has focused on toxins A and B. In this study, an immunoproteome‐based approach to identify immunogenic proteins located on the outer layers of C. difficile spores as potential candidates for the development of immunotherapy and/or diagnostic methods against this devastating infection is used.

Experimental design

To identify potential immunogenic proteins on the surface of C. difficile R20291, spore coat/exosporium extracts are separated by 2D electrophoresis (2‐DE) and analyzed for reactivity against C. difficile spore‐specific goat sera. Finally, the selected spots are in‐gel digested with chymotrypsin, peptides generated are separated by nanoUPLC followed by MS/MS using Quad‐TOF‐MS, corroborated by Ultimate 3000RS‐nano‐UHPLC coupled to Q‐Exactive‐Plus‐Orbitrap MS.

Results

The analysis identify five immunoreactive proteins: spore coat proteins CotE, CotA, and CotCB; exosporium protein CdeC; and a cytosolic methyltransferase.

Conclusion

This data provides a list of spore surface protein candidates as antigens for vaccine development against C. difficile infections.
2‐fluoro‐5‐maleimidobenzoic acid‐linked albumin drug (MAD) delivery for selective systemic targeting of metastatic prostate cancer
Authors: Akinboye Emmanuel S. , Rogers Oliver C. , Isaacs John T.
Published: March 2018

Background

The SH‐group at Cys‐34 of human serum albumin (HSA) is a unique and accessible functional group that can be exploited for efficient linkage of a maleimide containing cytotoxic drug derivative to albumin. The specific maleimide chemistry used for production of the maleimide‐linked albumin drug (MAD) is critical, however, to minimize the plasma concentration of “free” cytotoxic drug spontaneously released from albumin carrier thus decreasing dose‐limiting host toxicity while enhancing the plasma half‐life from minutes to days (ie, pharmacokinetic effect) and tissue concentration of the MAD in the extracellular cellular fluid at sites of cancer (ie, EPR effect).

Methods

To accomplish this goal, a chemical synthesis was developed using 2‐fluoro‐5‐maleimidobenzoic acid to stably link the potent cytotoxic chemically modified analogue of the naturally occurring sesquiterpene γ‐lactone, thapsigargin, 8‐O‐(12‐aminododecanoyl)‐8‐O‐debutanoyl thapsigargin (12ADT), to Cys‐34 of albumin to produce 12ADT‐MAD.

Results

Using FITC‐labeling, LC/MS analysis, and in vitro growth and clonogenic survival assays on a series of 6 human prostate cancer lines (LNCaP, LAPC‐4, VCap, CWR22Rv1, PC3, and Du145), we documented that 12ADT‐MAD is endocytosed by prostate cancer cells where it is degraded into its amino acids liberating cysteinyl‐maleimide‐12ADT which is both chemically stable at the acidic pH of 5.5 present in the endosome while retaining its high killing ability (IC50 50 nM) via SERCA inhibition.

Conclusions

Based upon these positive in vitro validation results, the in vivo efficacy versus host toxicity of this 12‐ADT‐MAD approach is presently being evaluated against a series of patient derived androgen responsive and castration resistant human xenografts in immune‐deficient mice.
A novel mouse model of human prostate cancer to study intraprostatic tumor growth and the development of lymph node metastases
Authors: Linxweiler Johannes , Körbel Christina , Müller Andreas , Hammer Markus , Veith Christian , Bohle Rainer M. , Stöckle Michael , Junker Kerstin , Menger Michael D. , Saar Matthias
Published: March 2018

Background

In this study, we aimed to establish a versatile in vivo model of prostate cancer, which adequately mimics intraprostatic tumor growth, and the natural routes of metastatic spread. In addition, we analyzed the capability of high‐resolution ultrasonography (hrUS), in vivo micro‐CT (μCT), and 9.4T MRI to monitor tumor growth and the development of lymph node metastases.

Methods

A total of 5 × 105 VCaP cells or 5 × 105 cells of LuCaP136‐ or LuCaP147 spheroids were injected into the prostate of male CB17‐SCID mice (n = 8 for each cell type). During 12 weeks of follow‐up, orthotopic tumor growth, and metastatic spread were monitored by repetitive serum‐PSA measurements and imaging studies including hrUS, μCT, and 9.4T MRI. At autopsy, primary tumors and metastases were harvested and examined by histology and immunohistochemistry (CK5, CK8, AMACR, AR, Ki67, ERG, and PSA). From imaging results and PSA‐measurements, tumor volume doubling time, tumor‐specific growth rate, and PSA‐density were calculated.

Results

All 24 mice developed orthotopic tumors. The tumor growth could be reliably monitored by a combination of hrUS, μCT, MRI, and serum‐PSA measurements. In most animals, lymph node metastases could be detected after 12 weeks, which could also be well visualized by hrUS, and MRI. Immunohistochemistry showed positive signals for CK8, AMACR, and AR in all xenograft types. CK5 was negative in VCaP‐ and focally positive in LuCaP136‐ and LuCaP147‐xenografts. ERG was positive in VCaP‐ and negative in LuCaP136‐ and LuCaP147‐xenografts. Tumor volume doubling times and tumor‐specific growth rates were 21.2 days and 3.9 %/day for VCaP‐, 27.6 days and 3.1 %/day for LuCaP136‐ and 16.2 days and 4.5 %/day for LuCaP147‐xenografts, respectively. PSA‐densities were 433.9 ng/mL per milliliter tumor for VCaP‐, 6.5 ng/mL per milliliter tumor for LuCaP136‐, and 11.2 ng/mL per milliliter tumor for LuCaP147‐xenografts.

Conclusions

By using different monolayer and 3D spheroid cell cultures in an orthotopic xenograft model, we established an innovative, versatile in vivo model of prostate cancer, which enables the study of both intraprostatic tumor growth as well as metastatic spread to regional lymph nodes. HrUS and MRI are feasible tools to monitor tumor growth and the development of lymph node metastases while these cannot be visualized by μCT.
Synthesis and physicochemical studies of amyloidogenic hexapeptides derived from human cystatin C
Authors: Iłowska Emilia , Sawicka Justyna , Szymańska Aneta
Published: March 2018

Human cystatin C (hCC) is a low molecular mass protein that belongs to the cystatin superfamily. It is an inhibitor of extracellular cysteine proteinases, present in all human body fluids. At physiological conditions, hCC is a monomer, but it has a tendency to dimerization. Naturally occurring hCC mutant, with leucine in position 68 substituted by glutamine (L68Q), is directly involved in the formation of amyloid deposits, independently of other proteins. This process is the primary cause of hereditary cerebral amyloid angiopathy, observed mainly in the Icelandic population. Oligomerization and fibrillization processes of hCC are not explained equally well, but it is proposed that domain swapping is involved in both of them. Research carried out on the fibrillization process led to new hypothesis about the existence of a steric zipper motif in amyloidogenic proteins. In the hCC sequence, there are 2 fragments which may play the role of a steric zipper: the loop L1 region and the C‐terminal fragment. In this work, we focused on the first of these. Nine hexapeptides covering studied hCC fragment were synthesized, and their fibrillogenic potential was assessed using an array of biophysical methods. The obtained results showed that the studied hCC fragment has strong profibrillogenic propensities because it contains 2 fragments fulfilling the requirements for an effective steric zipper located next to each other, forming 1 super‐steric zipper motif. This hCC fragment might therefore be responsible for the enhanced amyloidogenic properties of dimeric or partially unfolded hCC.
Multifunctional Polarization Converter Based on Dielectric Metamaterial
Authors: Gao Ju , Wang Cong , Qiang Tian , Zhang Kuang , Wu Qun
Published: March 2018

In this study, the development of a novel polarization converter using all‐dielectric‐based metamaterial, for the simultaneous high‐efficiency conversion of both linearly and circularly polarized electromagnetic waves is reported. Supported by the field transformation technique, the developed converter is analyzed based on two methods: the constituent parameter and the decoupling incident‐wave. Additionally, the inter‐relationship among the structural parameters of the proposed structure and the effect of their individual variations are well investigated. The simulation and experimental results indicate that the developed polarization converter, which operates at approximately 12 GHz, converts up to 99.9% of the induced wave into its cross‐polarized wave in the transmitted component. Moreover, the stability performance of the developed polarization converter reveals that the device exhibits moderate conversion efficiency over a wide incident‐wave‐angle variation range.
Reducing Optical Losses in GaN Waveguides – Toward an Electro‐Optic Phase Modulator
Authors: Westreich Ohad , Atar Gil , Paltiel Yossi , Sicron Noam
Published: March 2018

In recent years, gallium nitride (GaN) has been investigated as a potential material for various integrated photonic devices. A key component of integrated photonic devices is a voltage‐controlled phase modulator in an optical waveguide (WG) design. To date, the main obstacles in the realization of such a device are significant optical losses that are related to various mechanisms. In this research, the main factors for optical losses in a GaN phase modulator are experimentally studied. The suggested design is based on a reverse‐biased p–n junction ridge WG scheme. The losses are determined mainly using the Fabry–Perot method at a wavelength of 1064 nm, which is important for high‐optical‐power applications. The contribution of the ridge waveguide wall roughness losses, the p‐doped layer absorption, and the metallic p‐contacts is evaluated. Based on these results, an optimized structure of an electro‐optical GaN phase modulator is proposed. The modulator voltage response is calculated while taking optical polarization effects into account.
A Partially Etched Structure of Light‐Addressable Potentiometric Sensor for High‐Spatial‐Resolution and High‐Speed Chemical Imaging
Authors: Truong Hoang Anh , Werner Carl Frederik , Miyamoto Ko‐ichiro , Yoshinobu Tatsuo
Published: March 2018

In this study, a partially etched structure of a light‐addressable potentiometric sensor (LAPS) is fabricated for high‐spatial‐resolution and high‐speed imaging of chemical species. An anisotropic etching process based on tetramethylammonium hydroxide (TMAH) is optimized to fabricate the structure, which strikes a balance between the imaging performance and the mechanical strength of the sensor plate. The etched region of the sensor plate with a thickness of 47 µm yields a 12‐fold enhancement of the photocurrent signal at a high frequency of 120 kHz and a 10‐fold frequency bandwidth in comparison with the frame region with a thickness of 150 µm due to the reduced traveling distance of charge carriers inside the semiconductor. This result represents a new approach for high signal‐to‐noise ratio, high‐spatial‐resolution, and high‐speed measurement.
Pyroelectric Energy Harvesting Using Ferroelectric Ba1−xCaxTiO3
Authors: Hayashi Kei , Aikawa Eisuke , Ueno Toru , Kajitani Tsuyoshi , Miyazaki Yuzuru
Published: March 2018

The structural and pyroelectric properties of partially Ca‐substituted BaTiO3, Ba1−xCaxTiO3 (0 ≤ x ≤ 0.2), are investigated. Partial Ca‐substitution in BaTiO3 introduced tetragonal distortion in the TiO6 octahedrons and increased the displacement, Δd, of a Ti4+ cation from the center of an octahedron. This increase in Δd led to enhancement of remanent polarization and pyroelectric voltage, Vp. The pyroelectric energy storage behavior is demonstrated for the partially Ca‐substituted BaTiO3. For the Ba0.9Ca0.1TiO3 sample which exhibited the highest Vp, the stored energy in an output capacitor was proven to be sufficient to operate micropower Internet of Things devices.
Field‐Polarity‐Dependent Domain Growth in Epitaxial BaTiO3 Films
Authors: Roth Robert , Guo Er‐Jia , Rafique Mohsin , Dörr Kathrin
Published: March 2018

The growth of circular tip‐induced domains has been studied in epitaxial BaTiO3 (BTO) films as a function of writing voltage and time using piezoresponse force microscopy (PFM). While abundant for Pb(Zr,Ti)O3 (PZT) films, such studies are rare for BTO. Strong relaxation of written domains is observed in the form of reduction of the PFM amplitude inside the area of written domains which occurs additionally to a decrease of the domain radius. The domain wall velocity observed for negative tip voltage is systematically smaller than that for positive tip voltage. Based on maps of the positive and negative switching fields, the effective driving field for both polarities has been estimated. The polarity‐dependent effective field cannot account for the different velocities, indicating a polarity‐dependent mobility of the domain walls.
Study of the Interface Layers Between Si Nanoparticles and SiO2 Matrix Deposited by e‐Gun Evaporation
Authors: Pivac Branko , Dubček Pavo , Dasović Jasna , Zorc Hrvoje , Bernstorff Sigrid
Published: March 2018

The structural properties of Si nanoparticles (NPs) formed for application in advanced solar cells are explored. A superstructure consisting of Si NPs is formed after annealing of SiO2/Si‐based multilayers. The structural properties are explored by GISAXS/GIWAXS and photoluminescence analysis. Both the GISAXS and GIWAXS techniques are simultaneously used to obtain the size and shape of the grown objects, and in addition the GISAXS patterns are analyzed using the Porod theory to obtain information on the Si NPs/matrix interface. The GIWAXS analysis of multilayers with Si layer thickness of 2 or 4 nm confirms that in both cases already after annealing at only 900 °C crystalline particles are created, GISAXS reveals that depending on the initial thickness of the deposited Si layer (2 or 4 nm), the NPs formed after annealing have either sphere‐like (2 nm Si layer) or a combination of sphere and oblate‐like shapes (4 nm). The photoluminescence results support the assumption that the formed defect layer at the Si NP/matrix interface is dominantly responsible for the light emission. We further analyze the GISAXS data in the light of the Porod theory and the results support the model that the formed NPs are surrounded by a defected layer.
Preferential MBE Growth and Characterization of SiGe Nanoislands on Depth‐Selective Si Pits Etched by Ar+ Plasma
Authors: Şeker İsa , Karatutlu Ali , İstengir Sümeyra
Published: March 2018

In this study, the size selective deposition of SiGe nanoislands is demonstrated to be possible only in Si nanopits using a molecular beam epitaxy (MBE) system. The depth of the etched Si substrate prepared by Ar+ plasma etching just before the deposition seems to be playing a role in the selectivity of keeping the SiGe nanoislands only inside the nanopits. We observed that, when the thickness of the deposited SiGe layer is around the mean pit depth, which is 4 nm in this case, Ge nucleation takes place selectively on the pre‐etched pits. Relatively larger deposition thickness (e.g., 40 nm) is demonstrated to suppress the preferential growth of the Ge nanocrystals (NCs)/Si NCs which are in return observed all along the surface of the Si substrate. On the other hand, surface migration is considered to play a role in very small depth (relatively more shallow pits) and yielding the unfilled Si nanopits (ca. 1.5 nm) whereas Ge NCs selectively nucleate only within those having larger depths (ca. 3 nm). Such site‐specific 3D controlled growth of nanoislands is shown for the deposition of different semiconductor nanocrystals on top of another for formation of nanodevices fabricated in a single nanopit.
Ammonia‐Sensing Using a Composite of Graphene Oxide and Conducting Polymer
Authors: Hasani Amirhossein , Sharifi Dehsari Hamed , Asghari Lafmejani Milad , Salehi Alireza , Afshar Taromi Faramarz , Asadi Kamal , Kim Soo Young
Published: March 2018

The paper studies the performance of a gas sensor based on an organic/inorganic diode for ammonia (NH3) sensing under atmospheric conditions at room temperature and different humidity levels. The diode structure consists of a layer of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) deposited on top of n‐type GaAs. The PEDOT:PSS layer that is filled with different ratios of graphene oxide (GO) is prepared from the solution phase. We show that the current–voltage (I–V) response of­­­­­ the diode and the sensing performance improve significantly by adding GO to the PEDOT:PSS layer. The sensing response is highest for a diode with 0.04 wt.% of GO. At room temperature, the PEDOT:PSS:GO (0.04 wt.%)/n‐GaAs Schottky diode shows a sensitivity of 194 upon exposure to 20 ppm of NH3 with rapid response and recovery times between 95 and 121 s, respectively. The NH3 sensor based on PEDOT:PSS:GO is cost‐effective, environmentally friendly, and easy to fabricate using low‐cost solution‐processing methods.
The spatial distribution and temporal variability of föhn winds over the Larsen C ice shelf, Antarctica
Authors: Turton Jenny V. , Kirchgaessner Amelie , Ross Andrew N. , King John C.
Published: March 2018

The eastern side of the Antarctic Peninsula (AP) mountain range and the adjacent ice shelves are frequently affected by föhn winds originating from upwind of the mountains. Six automatic weather stations (AWSs) and archived model output from 5 km resolution Antarctic Mesoscale Prediction System (AMPS) forecasts have been combined to identify the occurrence of föhn conditions, and their spatial distribution over the Larsen C Ice Shelf (LCIS) from 2009 to 2012.

Algorithms for semi‐automatic detection of föhn conditions have been developed for both AWS and AMPS data. The frequency of föhn varies by location, being most frequent at the foot of the AP and in the north of the ice shelf. They are most common in spring, when they can prevail for 50% of the time. The results of this study have important implications for further research, investigating the impact of föhn on surface melting, and the surface energy budget of the ice shelf. This is of particular interest due to the collapse of Larsen A and B ice shelves in 1995 and 2002 respectively, and the potential instability issues following a large calving event on Larsen C in 2017.
In situ organic compound analysis on a meteorite surface by desorption electrospray ionization coupled with an Orbitrap mass spectrometer
Authors: Naraoka Hiroshi , Hashiguchi Minako
Published: March 2018

Rationale

Since extraterrestrial organic matter in meteorites is a very complex mixture that is hard to ionize due to its association with minerals, in situ analysis of polar organic compounds has never been performed. In addition, when studying powdered samples, spatial information of organic compounds is lost.

Methods

In situ molecular analysis and chemical imaging of polar organic compounds were performed on a meteorite surface by desorption electrospray ionization coupled with high‐resolution mass spectrometry (DESI‐HRMS) using an Orbitrap mass spectrometer.

Results

Many CHN compounds, including alkylated pyridine and imidazole homologues, were identified from the complex peaks by HRMS using a spray of electrically charged methanol with a spatial resolution of approximately 50 μm. The same alkylated homologues have the same spatial distribution in the meteorite matrix, while alkylpyridines occur in a different location from alkylimidazoles.

Conclusions

The compound distribution suggests a different source for each compound series or a chromatographic separation effect associated with fluid movement in the meteorite parent body. The DESI‐HRMS imaging will further our understanding of organic compound distribution with respect to mineral and water interactions in meteorites.
Axonal regeneration in zebrafish spinal cord
Authors: Ghosh Sukla , Hui Subhra Prakash
Published: March 2018

In the present review we discuss two interrelated events—axonal damage and repair—known to occur after spinal cord injury (SCI) in the zebrafish. Adult zebrafish are capable of regenerating axonal tracts and can restore full functionality after SCI. Unlike fish, axon regeneration in the adult mammalian central nervous system is extremely limited. As a consequence of an injury there is very little repair of disengaged axons and therefore functional deficit persists after SCI in adult mammals. In contrast, peripheral nervous system axons readily regenerate following injury and hence allow functional recovery both in mammals and fish. A better mechanistic understanding of these three scenarios could provide a more comprehensive insight into the success or failure of axonal regeneration after SCI. This review summarizes the present understanding of the cellular and molecular basis of axonal regeneration, in both the peripheral nervous system and the central nervous system, and large scale gene expression analysis is used to focus on different events during regeneration. The discovery and identification of genes involved in zebrafish spinal cord regeneration and subsequent functional experimentation will provide more insight into the endogenous mechanism of myelination and remyelination. Furthermore, precise knowledge of the mechanism underlying the extraordinary axonal regeneration process in zebrafish will also allow us to unravel the potential therapeutic strategies to be implemented for enhancing regrowth and remyelination of axons in mammals.
Association of genetic variants of PD1 with recurrent pregnancy loss
Authors: Hayashi Yuko , Nishiyama Takeshi , Nakatochi Masahiro , Suzuki Shugo , Takahashi Satoru , Sugiura‐Ogasawara Mayumi
Published: March 2018

Purpose

Programmed cell death 1 (PD1) and PD ligand 1 (PDL1) are speculated to have an important role in maintaining a normal pregnancy and there are also a few reports of an association between the single‐nucleotide polymorphisms (SNPs) of PD1 or PDL1 and diseases in humans. The association was examined between the polymorphisms of PD1, PDL1, CTLA4 and recurrent pregnancy loss (RPL).

Methods

The study group consisted of 243 women with two or more pregnancy losses and 176 parous women. The frequency of three SNPs of PD1, two of PDL1, and four of CTLA4 were compared between the patients and controls. Next, the subsequent live birth rates in the patients with RPL with and without risk alleles were examined.

Results

Two SNPs (rs36084323 and rs3481962) of PD1 were found to occur at significantly higher frequencies in the patient group than in the control group. The subsequent live birth rate of the patients with vs. without the risk alleles of rs36084323 and rs3481962 were 83.3% vs. 83.3% and 81.6% vs. 84.0%, respectively.

Conclusion

Variations of the PD1 gene were identified as risk factors for RPL. However, the presence or absence of the PD1 risk alleles had no predictive effect on the subsequent pregnancy outcome.
Resilience of riparian vegetation after restoration measures on River Inn
Authors: Bauer M. , Harzer R. , Strobl K. , Kollmann J.
Published: March 2018

River restoration is widely applied, although its effects are poorly understood, and degraded habitats might be difficult to improve. Moreover, there is a lack of monitoring as well as few systematic comparisons of restoration methods. This study presents results of a 4‐year monitoring on River Inn (southern Germany) investigating restoration by gravel or sand addition or embankment removal. The results were compared with reference sites that represent the pre‐restoration conditions. At the landscape scale, we analysed vegetation types based on aerial photographs, whereas at a smaller scale, we undertook vegetation surveys and evaluated species composition, growth, and life form, as well as the proportion of the target vegetation. After 4 years, the data indicated a “negative resilience” of the vegetation back to the state prior to restoration. The structural analysis revealed an extensive spread of reed at expense of bare soil. Thus, the species composition largely regressed to the pre‐restoration conditions, and neither annuals nor other pioneer species showed a long‐term benefit of river restoration. There were differences among the three restoration treatments after 2 years, but no longer after 4 years. However, the river restoration had three positive outcomes: (a) There was a temporary benefit for pioneer vegetation that most likely replenished the seed bank of the respective species, (b) the valuable reed communities showed resilience, and (c) the measures allowed some practical learning as expected for adaptive restoration.
Catchment characteristics predicting nitrogen and phosphorus losses in Finland
Authors: Röman E. , Ekholm P. , Tattari S. , Koskiaho J. , Kotamäki N.
Published: March 2018

Empirical relationships between catchment properties and nutrient losses are often derived from spatially restricted data, which hampers the ability to more widely generalize the results. In this study, we regressed the catchment characteristics and the losses of total nitrogen (TN) and total phosphorus (TP) for all monitored catchments in Finland with adequate data (n = 59, from the year 2000 to 2011). TN loss was found to increase with the percentage of arable land and amount of point source loading and to decrease with increasing lake percentage. TP loss also increased not only with the percentage of arable land but also with fine‐grained soils (Cambisols) in the catchment and decreased with the percentage of lakes. Urban areas, scattered settlements, and N deposition were not significant explanatory variables, possibly due to their spatial covariation with arable land in Finland. Despite the fact that only a few significant explanatory variables were identified, the models explained the TN and TP losses by up to 91% and 92%, respectively.
Concise Review: Stem Cell Fate Guided By Bioactive Molecules for Tendon Regeneration
Authors: Zhang Yan-Jie , Chen Xiao , Li Gang , Chan Kai-Ming , Heng Boon Chin , Yin Zi , Ouyang Hong-Wei
Published: March 2018

Tendon disorders, which are commonly presented in the clinical setting, disrupt the patients’ normal work and life routines, and they damage the careers of athletes. However, there is still no effective treatment for tendon disorders. In the field of tissue engineering, the potential of the therapeutic application of exogenous stem cells to treat tendon pathology has been demonstrated to be promising. With the development of stem cell biology and chemical biology, strategies that use inductive tenogenic factors to program stem cell fate in situ are the most easily and readily translatable to clinical applications. In this review, we focus on bioactive molecules that can potentially induce tenogenesis in adult stem cells, and we summarize the various differentiation factors found in comparative studies. Moreover, we discuss the molecular regulatory mechanisms of tenogenesis, and we examine the various challenges in developing standardized protocols for achieving efficient and reproducible tenogenesis. Finally, we discuss and predict future directions for tendon regeneration.