bluuebunny/crossref_metadata_2025 huggingface dataset:
Consortium of plant growth‐promoting bacteria improves spinach (Spinacea oleracea L.) growth under heavy metal stress conditions
Authors: Shilev Stefan , Babrikova Ivelina , Babrikov Todor
Published: May 2019

BACKGROUND

Heavy metal contamination results in oxidative stress to plants and leads to decreased plant growth and development. Affected plants cannot be efficiently used in phytoremediation studies and their potential may be significantly reduced. In many cases, bioaugmentation with plant growth‐promoting bacteria is used as a strategy to alleviate this stress condition.

RESULTS

Isolates were found to possess 1‐aminocyclopropane‐1‐carboxylate (ACC) deaminase, to produce indole‐3‐acetic acid (IAA) siderophores and to solubilize phosphates, while identification revealed that the isolates belonged to the genera Pseudomonas and Bacillus. Out of the 17 isolates, ten were found to possess ACC deaminase activity, producing 1–3.2 μmol mg−1 h−1 of α‐ketobutyrate and siderophores of catechol and hydroxamate type. A higher quantity of IAA was observed in the case of isolate SGPI 41 (65 μg mL−1). In addition, the inoculation of consortia of isolates led to decreased accumulation of Cd, Pb and Zn in the whole plant but at the same time increased the plant biomass by up to 100% compared with the un‐inoculated control.

CONCLUSIONS

The use of beneficial bacteria possessing plant growth‐promoting traits is a very useful approach to alleviating heavy metal stress to plants and can be successfully applied in phytoremediation strategies. © 2019 Society of Chemical Industry
Right heart masses in a patient with endometrial stromal sarcoma
Authors: Tadic Marijana , Belyavskiy Evgeny , Cuspidi Cesare , Pieske Burkert , Haßfeld Sabine
Published: May 2019

We present the case of a 61‐year‐old woman with a large tumoral infiltration extending from the pelvis throughout the inferior vena cava inferior to the right atrium, protruding into the right ventricle and right ventricular outflow tract. She had been treated 10 years before for low‐grade endometrial stromal sarcoma by hysterectomy and adnexectomy followed by hormone‐ and radio‐therapy. Due to cancer recurrence, she underwent peritonectomy, appendectomy, and resection of terminal ileum.
Morphology of the third instar larva of Colobopterus quadratus (Coleoptera: Scarabaeidae: Aphodiinae) using scanning electron microscopy
Authors: Li Ce , Lu Ying , Fang Hong , Jiang Lu
Published: May 2019

Aphodiinae are a large cosmopolitan subfamily of Scarab beetles (Scarabaeoidea: Scarabaeidae), playing an important role during dung decomposition. Many aspects, especially immature stages, of these dung beetles have not yet been recorded due to their comparative small body sizes and lacking of striking rolling behavior. In this study, the third instar larva of Colobopterus quadratus is morphologically described using scanning electron microscopy. The larva is atypical for the combination of following morphological features: (a) the larval antennae are five‐segmented; (b) the clypeus bears 4 minute protuberances on dorsal surface; (c) the epitorma on epipharynx is ventrally protuberant; (d) the scissorial area of left mandible is broad and blade‐like; (e) the raster is furnished with six glabrous protuberances and two rows of pali arranged in V‐shape. Some significant ultra‐morphological features were discovered in larval Aphodiinae for the first time. The presence of blade‐like incisor on the left mandible implies the potential root cutting ability.
Synthesis of Novel Trifluoromethyl Group Containing Pyrido Furo/Thieno Pyrimidinone Derivatives and Their Anticancer Activity
Authors: Racha Hanumandlu , Vadla Balakishan , Peddolla Kavitha , Betala Sailu
Published: May 2019

A series of novel trifluoromethyl group containing pyridofuro/thieno pyrimidinone derivatives 5a–p were prepared starting from 2‐oxo/thioxo‐6‐phenyl/thien‐2‐yl‐4‐(trifluoromethyl)‐1,2‐dihydropyridine‐3‐carbonitrile 1 compound on reaction with bromoethylacetate and further different primary aliphatic amines, under their refluxing conditions to afford amide tagged furo/thieno pyridine derivatives 4. Compound 4 on reaction with trifluoroacetic acid and obtained novel trifluoromethyl group containing pyridofuro/thieno pyrimidinone derivatives 5a–p. All the synthesized compounds 5a–p were tested for anticancer activity on four cancer cell lines such as HeLa cervical cancer (CCL‐2), COLO 205 colon cancer (CCL‐222), HepG2 liver cancer (HB‐8065), MCF7 breast cancer (HTB‐22), and one normal cell line (HEK 293); compounds 5m, 5n, and 5p are found to be more promising anticancer activity at micromolar concentration and found to be nontoxic on normal cell line.
Synthesis of 4‐Hydroxy‐3‐(2‐arylimidazo[1,2‐a]pyridin‐3‐yl)quinolin‐2(1H)‐ones in the Presence of DABCO as an Efficient Organocatalyst
Authors: Khalafy Jabbar , Etivand Nasser , Poursattar Marjani Ahmad , Khalillou Neda
Published: May 2019

The one‐pot, three‐component, synthesis of a new series of 4‐hydroxy‐3‐(2‐arylimidazo[1,2‐a]pyridin‐3‐yl)quinolin‐2(1H)‐ones in the presence of DABCO as a catalyst has been achieved using aryl glyoxal monohydrates, quinoline‐2,4(1H,3H)‐dione, and 2‐aminopyridine in H2O/EtOH under reflux conditions. The cheapness of organocatalyst, simple workup, operational simplicity, regioselectivity, and high yields are some advantages of this protocol.
Intraseasonal modulation of spring‐strong wind events associated with convection in northeastern Argentina
Authors: Otero Federico , Alvarez Mariano S. , Salio Paola , Vera Carolina
Published: May 2019

The relationship between intraseasonal variability (IS; 10–90 days) and days which registered convection‐associated strong surface wind events (CSSWE) over northeastern Argentina (NEA) was studied. The climatological behaviour of these strong wind events showed a higher duration and occurrence in austral spring. CSSWE were categorized as a function of the wet and dry phases of the spring‐season intraseasonal (spring‐SIS) index, which describes the activity of the leading pattern of IS‐filtered outgoing longwave radiation (IS‐OLR) during that season in eastern South America. A modulation of the IS variability over localized and mesoscale phenomena as the CSSWE was found, showing significant peaks of wind variability in that timescale, and especially the submonthly timescale. The CSSWE were categorized according to the phases of the spring‐SIS pattern and most of them occurred before or during a wet phase, especially for the longer CSSWE. Moreover, the detection of CSSWE days during and before a dry phase was scarce. Rossby wave trains were observed to organize the circulation on intraseasonal timescales that configure regional cyclonic anomalies in such way that favours the development of CSSWE, promoting mid‐level ascents over NEA and northerly advection of humidity to the region. Together with the composites of IS‐OLR anomalies and the spectra of wind velocity, they support the fact that the higher‐frequency IS variability is the primary influence for the development of CSSWE.
Oral cancer on the gingiva in patients with proliferative leukoplakia: A study of 30 cases
Authors: Bagan Jose , Murillo‐Cortes Judith , Leopoldo‐Rodado Manuel , Sanchis‐Bielsa Jose M. , Bagan Leticia
Published: May 2019

Background

Proliferative verrucous leukoplakia, recently coined as proliferative leukoplakia (PL), is associated with a strong tendency to recur after treatment and an elevated rate of malignant transformation. We compared the clinical characteristics of patients with gingival PL with and without progression to oral squamous cell carcinoma.

Methods

The patients were divided into two groups: group 1 included 33 patients with gingival PL that did not progress to cancer, and group 2 included 30 patients with PL who developed malignant transformation during follow‐up. We compared age, sex, tobacco habit, clinical characteristics of gingival PL lesions, and location, tumor‐node‐metastasis (TNM) stage, and clinical characteristics of gingival malignancy between groups.

Results

Female sex was predominant in the group with gingival cancer, and simultaneous involvement of the buccal mucosa, tongue, and palate was more common in this group than in the group without cancer. PL lesions were also largest in the group of patients with cancer. Most gingival cancer occurred in areas with teeth and took the form of oral ulceration. TNM stage I was most common.

Conclusions

The simultaneous presence of lesions on the buccal mucosa, grade of lesion extension, and presence of ulcerative lesion were significantly associated with gingival cancer in patients with PL.
Determination of multiple pesticide residues in teas by gas chromatography with accurate time‐of‐flight mass spectrometry
Authors: Li Jianxun , Teng Xiaoyu , Wang Wenwen , Zhang Zijuan , Fan Chunlin
Published: May 2019

In this work, gas chromatography tandem with electron ionization and full‐scan high‐resolution mass spectrometry with a time‐of‐flight mass analyzer was evaluated for analyzing pesticide residues in teas. The relevant aspects for mass spectrometry analysis, including the resolution and mass accuracy, acquisition rate, temperature of ion source, were investigated. Under acquisition condition in 2‐GHz extended dynamic range mode, accurate mass spectral library including 184 gas chromatography detectable pesticides was established and retrieval parameters were optimized. The mass spectra were consistent over a wide concentration range (three orders) with good match values to those of NIST (EI‐quadrupole). The methodology was verified by the validation of 184 pesticides in four tea matrices. A wide linear range (1–1000 μg/kg) was obtained for most compounds in four matrices. Limit of detection, limit of quantification, and limit of identification values acquired in this study could satisfy the requirements for maximum residue levels prescribed by the European Community. Recovery studies were performed at three concentrations (10, 50, and 100 μg/kg). Most of the analytes were recovered at an acceptable range of 70–120% with relative standard deviations ≤ 20% in four matrices. The potential extension of qualitative screening scope makes gas chromatography tandem with electron ionization and mass spectrometry with a time‐of‐flight mass analyzer a more powerful tool compared with gas chromatography with tandem mass spectrometry.
Yttria‐based sol–gel coating for capillary microextraction online coupled to high‐performance liquid chromatography
Authors: Jillani Shehzada Muhammad Sajid , Alhooshani Khalid
Published: May 2019

This work about the development of yttria‐based polymeric coating using [bis(hydroxyethyl) amine] terminated polydimethylsiloxanes and yttrium trimethoxyethoxide inside the capillary. The coated capillary was utilized for online capillary microextraction and high‐performance liquid chromatography analysis. The prepared coating material was characterized using scanning electron microscopy, X‐ray photoelectron spectroscopy, energy dispersive X‐ray spectrometry, and thermogravimetric analysis. The coated capillary with polymer presented better extraction efficiency compared with the pure yttria‐based coated capillary with applicability in extreme pH environments (pH 0–pH 14). Excellent extraction towards polyaromatic hydrocarbons, aldehydes, ketones, alcohols, phenols, and amides was observed with limit of detection ranging from 0.18 to 7.35 ng/mL (S/N = 3) and reproducibility in between 0.6 and 6.8% (n = 3). Capillary‐to‐capillary extraction analysis has presented reproducibility between 4.1 and 9.9%. The analysis provided linear response for seven selected phenols in the range of 5–200 ng/mL with R2 values between 0.9971 and 0.9998. The inter‐day, intra‐day, and capillary‐to‐capillary reproducibility for phenols was also <10%. Real sample analysis by spiking 5, 50, and 200 ng/mL of phenols in wastewater and pool‐water produced recovery between 84.7 and 94.3% and reproducibility within 7.6% (n = 3).
Wound Complications in Head and Neck Squamous Cell Carcinomas After Anti–PD‐1 Therapy
Authors: Hwang Victoria , Mendez Eduardo , Chow Laura Q. M. , Futran Neal David , Andersen Peter , Li Ryan , Divi Vasu , Rodriguez Cristina P.
Published: May 2019

Immune checkpoint inhibitors have demonstrated activity in recurrent/metastatic head and neck squamous cell cancer, but less is known regarding their long‐term sequelae. We describe four patients who, after complete responses to anti–PD‐1 therapy, developed complications requiring surgical intervention. Patient 1 is a 57‐year‐old female whose marked tumor regression exposed some mandibular hardware. Patient 2 is a 39‐year‐old male who developed an ulcerated buccal lesion with exposed mandible. Patient 3 is a 66‐year‐old male with craniofacial osteoradionecrosis. Patient 4 is a 71‐year‐old male who developed an exposed and fractured mandible. All patients successfully underwent surgical intervention and remain disease free. Laryngoscope, 129:E428–E433, 2019
Peripheral Vestibular Organ Degeneration After Temporal Bone Fracture: A Human Otopathology Study
Authors: Knoll Renata M. , Ishai Reuven , Lubner Rory J. , Trakimas Danielle R. , Brodsky Jacob R. , Jung David H. , Rauch Steven D. , Nadol Joseph B. , Remenschneider Aaron K. , Kozin Elliott D.
Published: May 2019

Objectives/Hypothesis

Vestibular symptoms are a common sequela of temporal bone fractures (TBFs). The mechanisms of injury to the peripheral vestibular system following TBF, however, are not well described. Herein, we aimed to investigate the histopathology of the peripheral vestibular system in patients who sustained TBFs.

Study Design

Retrospective human specimen analysis.

Methods

Specimens from the National Temporal Bone Pathology Registry with (cases) and without (controls) TBFs were evaluated. Specimens were analyzed by light microscopy for vestibular hair cell and/or dendritic degeneration, presence of endolymphatic hydrops, blockage of the endolymphatic duct, and number of Scarpa ganglion cells (ScGCs) in the superior and inferior vestibular nerves.

Results

Seven temporal bones (TBs) from five individuals with TBFs, and seven TBs from six age‐matched individuals without a history of head injury met inclusion and exclusion criteria. All fractures involved the otic capsule. Severe degeneration of the cristae was identified in the semicircular canals in all TBF cases. The utricular and saccular maculae showed mild to severe degeneration in the TBF cases. Vestibular hydrops (n = 2 TBs) and blockage of the endolymphatic duct (n = 3 TBs) were also present in the TBF cases. There was a decrease of 52.6% in the mean total ScGC count in the TBF cases (n = 3 TBs) compared to age‐matched controls (n = 7 TBs,P =.015). There was a mean loss of 53% of the ScGCs in the superior vestibular nerve and a mean loss of 52.3% of the ScGCs in the inferior vestibular nerve compared to age‐matched controls (P =.033 andP =.021, respectively).

Conclusions

In a cohort of patients with TBFs, there were distinct peripheral vestibular changes including reduction of ScGCs.

Level of Evidence

NA

Laryngoscope, 130:752–760, 2020
African dryland ecosystem changes controlled by soil water
Authors: Wei Fangli , Wang Shuai , Fu Bojie , Wang Lixin , Liu Yi Y. , Li Yan
Published: May 2019

Monitoring long‐term vegetation dynamics in African drylands is of great importance for both ecosystem degradation studies and carbon‐cycle modelling. Here, we exploited the complementary use of optical and passive microwave satellite data— normalized difference vegetation index (NDVI) and vegetation optical depth (VOD)—to provide new insights of ecosystem changes in African drylands. During 1993–2012, 54% of African drylands experienced a significant increase of VOD, mainly located in southern Africa and west and central Africa, with an average rate of increase of (1.2 ± 2.7) × 10−3 yr−1. However, a significant decreasing NDVI was observed over 43% of the African drylands, in particular in western Niger and eastern Africa, with an average browning rate of (−0.13 ± 1.5) × 10−3 yr−1. The contrasting vegetation trends (increasing VOD and decreasing NDVI) were largely caused by an increase in the relative proportion of the woody component of the vegetation, as a result of the prevailing woody encroachment in African drylands during the study period. Soil water emerges as the dominant driver of ecosystem changes in African drylands, in particular in arid and semiarid areas. This is evidenced by a strong spatio‐temporal correlation between soil water and vegetation, where soil water changes explain about 48% of vegetation variations. This study emphasizes the potential of utilizing multiple satellite products with different strengths in monitoring different characteristics of ecosystems to evaluate ecosystem changes and reveal the underlying mechanisms of the observed changes.
A Multifunctional Photonic Integrated Circuit for Diverse Microwave Signal Generation, Transmission, and Processing
Authors: Zou Xihua , Zou Fang , Cao Zizheng , Lu Bing , Yan Xianglei , Yu Ge , Deng Xiong , Luo Bin , Yan Lianshan , Pan Wei , Yao Jianping , Koonen Antonius M. J.
Published: May 2019

Microwave photonics (MWP) studies the interaction between microwaves and optical waves for the generation, transmission, and processing of microwave signals (i.e., three key domains), taking advantage of the broad bandwidth and low loss offered by modern photonics. Integrated MWP using photonic integrated circuits (PICs) can reach a compact, reliable, and green implementation. Most PICs, however, are recently developed to perform one or more functions restricted inside a single domain. Herein, as highly desired, a multifunctional PIC is proposed to cover the three key domains. The PIC is fabricated on an InP platform by monolithically integrating four laser diodes and two modulators. Using the multifunctional PIC, seven fundamental functions across microwave signal generation, transmission, and processing are demonstrated experimentally. Outdoor field trials for electromagnetic environment surveillance along in‐service high‐speed railways are also performed. The success of such a PIC marks a key step forward for practical and massive MWP implementations.
High‐Speed and High‐Responsivity Hybrid Silicon/Black‐Phosphorus Waveguide Photodetectors at 2 µm
Authors: Yin Yanlong , Cao Rui , Guo Jingshu , Liu Chaoyue , Li Jiang , Feng Xianglian , Wang Huide , Du Wei , Qadir Akeel , Zhang Han , Ma Yungui , Gao Shiming , Xu Yang , Shi Yaocheng , Tong Limin , Dai Daoxin
Published: May 2019

Silicon photonics is being extended from the near‐infrared window of 1.3–1.5 µm for optical fiber communications to the mid‐infrared (mid‐IR) wavelength‐band of 2 µm or longer for satisfying the increasing demands in many applications. Mid‐IR waveguide photodetectors on silicon have attracted intensive attention as one of the indispensable elements for various photonic systems. However, when combining traditional semiconductor materials with silicon, there are some challenges due to lattice mismatch and thermal expansion mismatch. As an alternative, two‐dimensional (2D) materials provide a new and promising option for enabling active photonic devices on silicon. Here black‐phosphorus (BP) thin films with optimized medium thicknesses (≈40 nm) are introduced as the active material for light absorption and silicon/BP hybrid ridge waveguide photodetectors at 2 µm are demonstrated with a high responsivity of 306.7 mA W−1 at a low bias voltage of 0.4 V. The 3 dB‐bandwidth is up to 1.33 GHz and an experiment of a 4.0 Gbit s−1 data receiving is also demonstrated.
Ends, tangles and critical vertex sets
Authors: Kurkofka Jan , Pitz Max
Published: May 2019

We show that an arbitrary infinite graph G can be compactified by its ends plus its critical vertex sets, where a finite set X of vertices of an infinite graph is critical if its deletion leaves some infinitely many components each with neighbourhood precisely equal to X. We further provide a concrete separation system whose ℵ0‐tangles are precisely the ends plus critical vertex sets. Our tangle compactification is a quotient of Diestel's (denoted by ), and both use tangles to compactify a graph in much the same way as the ends of a locally finite and connected graph compactify it in its Freudenthal compactification. Finally, generalising both Diestel's construction of and our construction of , we show that G can be compactified by every inverse limit of compactifications of the sets of components obtained by deleting a finite set of vertices. Diestel's is the finest such compactification, and our is the coarsest one. Both coincide if and only if all tangles are ends. This answers two questions of Diestel.
Necessary and sufficient conditions for oscillation of second‐order dynamic equations on time scales
Authors: Zhou Yong , Ahmad Bashir , Alsaedi Ahmed
Published: May 2019

In this paper, we establish necessary and sufficient conditions for oscillation of second‐order strongly superlinear and strongly sublinear dynamic equations. Our results unify and improve many known results in the literature.
Integrative neuromuscular medicine: Neuropathy and neuropathic pain: Consider the alternatives
Authors: Rowin Julie
Published: May 2019

Complementary and alternative treatment modalities are commonly utilized by patients for neuropathy and neuropathic pain due to perceived lack of benefit from conventional medical treatment. As the association between metabolic syndrome and neuropathy is increasingly recognized, diet and lifestyle interventions are becoming important components in the management of neuropathy. Progress in the understanding of the gut–immune interaction highlights the role the gut microbiome and inflammation plays in the modulation of neuropathy and neuropathic pain. Evidence for nutritional interventions, exercise, supplements, acupuncture, and mindfulness‐based practices in the treatment of neuropathic pain is encouraging. This article reviews the available evidence to support the safe use of complementary and alternative treatments for commonly encountered conditions associated with neuropathy and neuropathic pain. Muscle Nerve 60: 124–136, 2019
Synthesis of a novel DPPA‐containing benzoxazine to flame‐retard epoxy resin with maintained thermal properties
Authors: Luo Qinqin , Sun Yulin , Yu Biao , Li Chengpeng , Song Jiangli , Tan Dexin , Zhao Jianqing
Published: May 2019

The flame‐retarded epoxy resin with improved thermal properties based on environmentally friendly flame retardants is vital for industrial application. Hereby, a novel reactive‐type halogen‐free flame retardant, 10‐(3‐(4‐hydroxy phenyl)‐3,4‐dihydro‐2H‐benzo[e] [1,3] oxazin‐4‐yl)‐5H‐phenophosphazinine 10‐oxide (DHA‐B) was synthesized via a two‐step reaction route. Its structure was characterized using 1H, 13C, and 31P NMR and HRMS spectra. For 4,4′‐diaminodipheny ethane (DDM) and diglycidyl ether of bisphenol A (DGEBA)‐cured systems, the epoxy resin with only 2 wt% loading of DHA‐B passed V‐0 rating of UL‐94 test. Significantly, its glass transition temperature (Tg) and initial decomposition temperature (T5%) were as high as 169.6°C and 359.6°C, respectively, which were even higher than those of the corresponding original epoxy resin. Besides, DHA‐B decreased the combustion intensity during combustion. The analysis of residues after combustion suggested that DHA‐B played an important role in the condensed phase.
Induced birefringence of rubbed and stretched polyvinyl alcohol foils as alignment layers for nematic molecules
Authors: Nechifor Cristina‐Delia , Postolache Mihai , Albu Raluca Marinica , Barzic Andreea Irina , Dorohoi Dana‐Ortansa
Published: May 2019

Some optical properties of poly (vinyl alcohol) (PVA) films are investigated prior and after the rubbing and stretching of the samples. Birefringence of the prepared foils is enhanced as their stretching degree and rubbing become larger. These processing factors are also affecting the values of the ordinary and extraordinary refractive indices. The induced anisotropy in PVA foils is evidenced in the morphological characteristics observed by optical microscopy. The spreading and adhesion behaviors of a nematic liquid crystal on PVA foils are analyzed by means of contact angle measurements. Preliminary testing of the nematic on the PVA films revealed significant variations in transmitted light intensity during sample rotation under crossed polarizers. The high contrast between dark and bright patterns is indicative of uniform and homogenous alignment of nematic on the rubbed and stretched PVA foils.
Multivariate analysis reveals environmental and genetic determinants of element covariation in the maize grain ionome
Authors: Fikas Alexandra Asaro , Dilkes Brian P. , Baxter Ivan
Published: May 2019

The integrated responses of biological systems to genetic and environmental variation result in substantial covariance in multiple phenotypes. The resultant pleiotropy, environmental effects, and genotype‐by‐environmental interactions (GxE) are foundational to our understanding of biology and genetics. Yet, the treatment of correlated characters, and the identification of the genes encoding functions that generate this covariance, has lagged. As a test case for analyzing the genetic basis underlying multiple correlated traits, we analyzed maize kernel ionomes from Intermated B73 x Mo17 (IBM) recombinant inbred populations grown in 10 environments. Plants obtain elements from the soil through genetic and biochemical pathways responsive to physiological state and environment. Most perturbations affect multiple elements which leads the ionome, the full complement of mineral nutrients in an organism, to vary as an integrated network rather than a set of distinct single elements. We compared quantitative trait loci (QTL) determining single‐element variation to QTL that predict variation in principal components (PCs) of multiple‐element covariance. Single‐element and multivariate approaches detected partially overlapping sets of loci. QTL influencing trait covariation were detected at loci that were not found by mapping single‐element traits. Moreover, this approach permitted testing environmental components of trait covariance, and identified multi‐element traits that were determined by both genetic and environmental factors as well as genotype‐by‐environment interactions. Growth environment had a profound effect on the elemental profiles and multi‐element phenotypes were significantly correlated with specific environmental variables.
Low‐Temperature, Rapid Copolymerization of Acrylic Acid and Sodium Acrylate in Water
Authors: Narupai Benjaporn , Willenbacher Johannes , Bates Morgan W. , Barbon Stephanie M. , Zerdan Raghida Bou , McGrath Alaina J. , Lee In‐Hwan , Anastasaki Athina , Discekici Emre H. , Laitar David S. , Van Dyk Antony K. , Kalantar Tom H. , Ren Jing M. , Hawker Craig J.
Published: May 2019

Regulating the aqueous polymerization of acrylic acid (AA) is a major opportunity for future materials design, requiring the development of scalable, industry‐oriented procedures that afford modest molar mass and dispersity control without long reaction times and environmentally demanding conditions. To address these challenges, this report presents the rapid copolymerization of aqueous mixtures of AA and sodium acrylate using an inexpensive and scalable protocol based on alkyl iodides/sodium iodide as mediators in water. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1414–1419
Plasticity and transient binding are key ingredients of the periplasmic chaperone network
Authors: Chum Aaron P. , Shoemaker Sophie R. , Fleming Patrick J. , Fleming Karen G.
Published: May 2019

SurA, Skp, FkpA, and DegP constitute a chaperone network that ensures biogenesis of outer membrane proteins (OMPs) in Gram‐negative bacteria. Both Skp and FkpA are holdases that prevent the self‐aggregation of unfolded OMPs, whereas SurA accelerates folding and DegP is a protease. None of these chaperones is essential, and we address here how functional plasticity is manifested in nine known null strains. Using a comprehensive computational model of this network termed OMPBioM, our results suggest that a threshold level of steady state holdase occupancy by chaperones is required, but the cell is agnostic to the specific holdase molecule fulfilling this function. In addition to its foldase activity, SurA moonlights as a holdase when there is no expression of Skp and FkpA. We further interrogate the importance of chaperone–client complex lifetime by conducting simulations using lifetime values for Skp complexes that range in length by six orders of magnitude. This analysis suggests that transient occupancy of durations much shorter than the Escherichia coli doubling time is required. We suggest that fleeting chaperone occupancy facilitates rapid sampling of the periplasmic conditions, which ensures that the cell can be adept at responding to environmental changes. Finally, we calculated the network effects of adding multivalency by computing populations that include two Skp trimers per unfolded OMP. We observe only modest perturbations to the system. Overall, this quantitative framework of chaperone–protein interactions in the periplasm demonstrates robust plasticity due to its dynamic binding and unbinding behavior.
Tracing the evolution of novel features of human Toll‐like receptor 4
Authors: Anderson Jeremy A. , Loes Andrea N. , Waddell Grace L. , Harms Michael J.
Published: May 2019

Toll‐like receptor 4 (TLR4) is a critical innate immune protein that activates inflammation in response to extracellular cues. Much of the work to understand how the protein works in humans has been done using mouse models. Although human and mouse TLR4 have many shared features, they have also diverged significantly since their last common ancestor, acquiring 277 sequence differences. Functional differences include the extent of ligand‐independent activation, whether lipid IVa acts as an antagonist or agonist, and the relative species cross‐compatibility of their MD‐2 cofactor. We set out to understand the evolutionary origins for these functional differences between human and mouse TLR4. Using a combination of phylogenetics, ancestral sequence reconstruction, and functional characterization, we found that evolutionary changes to the human TLR4, rather than changes to the mouse TLR4, were largely responsible for these functional changes. Human TLR4 repressed ancestral ligand‐independent activity and gained antagonism to lipid IVa. Additionally, mutations to the human TLR4 cofactor MD‐2 led to lineage‐specific incompatibility between human and opossum TLR4 complex members. These results were surprising, as mouse TLR4 has acquired many more mutations than human TLR4 since their last common ancestor. Our work has polarized this set of transitions and sets up work to study the mechanistic underpinnings for the evolution of new functions in TLR4.
Biopesticide based sustainable pest management for safer production of vegetable legumes and brassicas in Asia and Africa
Authors: Srinivasan Ramasamy , Sevgan Subramanian , Ekesi Sunday , Tamò Manuele
Published: May 2019

Vegetables are one of the important crops which could alleviate poverty and malnutrition among the smallholder farmers in tropical Asia and Africa. However, a plethora of pests limit the productivity of these crops, leading to economic losses. Vegetable producers overwhelmingly rely on chemical pesticides in order to reduce pest‐caused economic losses. However, over‐reliance on chemical pesticides poses serious threats to human and environmental health. Hence, biopesticides offer a viable alternative to chemical pesticides in sustainable pest management programs. Baculoviruses such as nucleopolyhedrovirus (NPV) and granulovirus (GV) have been exploited as successful biological pesticides in agriculture, horticulture and forestry.Maruca vitratamultiple nucleocapsid NPV (MaviMNPV) was found to be a unique baculovirus specifically infecting pod borer on food legumes, and it has been successfully developed as a biopesticide in Asia and Africa. Entomopathogenic fungi also offer sustainable pest management options. Several strains ofMetarhizium anisopliaeandBeauveria bassianahave been tested and developed as biopesticides in Asia and Africa. This review specifically focuses on the discovery and development of entomopathogenic virus and fungi‐based biopesticides against major pests of vegetable legumes and brassicas in Asia and Africa. © 2019 Society of Chemical Industry
Synthesis of alpha‐methyl selenocysteine and its utilization as a glutathione peroxidase mimic
Authors: Wehrle Robert J. , Ste.Marie Emma J. , Hondal Robert J. , Masterson Douglas S.
Published: May 2019

Selenocysteine (Sec) is the 21st amino acid in the genetic code where this amino acid is primarily involved in redox reactions in enzymes because of its high reactivity toward oxygen and related reactive oxygen species. Sec has found wide utility in synthetic peptides, especially as a replacement for cysteine. One limitation of using Sec in synthetic peptides is that it can undergo β‐syn elimination reactions after oxidation, rendering the peptide inactive due to loss of selenium. This limitation can be overcome by substituting Cα‐H with a methyl group. The resulting Sec derivative is α‐methylselenocysteine ((αMe)Sec). Here, we present a new strategy for the synthesis of (αMe)Sec by alkylation of an achiral methyl malonate through the use of a selenium‐containing alkylating agent synthesized in the presence of dichloromethane. The seleno‐malonate was then subjected to an enzymatic hydrolysis utilizing pig liver esterase followed by a Curtius rearrangement producing a protected derivative of (αMe)Sec that could be used in solid‐phase peptide synthesis. We then synthesized two peptides: one containing Sec and the other containing (αMe)Sec, based on the sequence of glutathione peroxidase. This is the first reported incorporation of (αMe)Sec into a peptide as well as the first reported biochemical application of this unique amino acid. The (αMe)Sec‐containing peptide had superior stability as it could not undergo β‐syn elimination and it also avoided cleavage of the peptide backbone, which we surprisingly found to be the case for the Sec‐containing peptide when it was incubated for 96 hours in oxygenated buffer at pH 8.0.
Impact of Cone‐Shape‐Patterned Sapphire Substrate and Temperature on the Epitaxial Growth of p‐GaN via MOCVD
Authors: Yao Weizhen , Wang Lianshan , Li Fangzheng , Meng Yulin , Yang Shaoyan , Wang Zhanguo
Published: May 2019

In this paper, the authors report both the effects of the cone‐shape‐patterned sapphire substrate (CSPSS) and the growth temperature on surface morphology and crystalline quality of the p‐GaN layers, grown via metal‐organic chemical vapor deposition (MOCVD). Low‐temperature GaN buffer and high‐temperature undoped GaN (u‐GaN) coalescence layers are grown between p‐GaN epitaxial film and substrate for all the samples. The time evolution of surface morphology of those films is monitored by scanning electron microscope (SEM) in order to investigate the growth mechanism of films on CSPSS. The compressive stresses in the p‐GaN films is also discussed. From atomic force microscopy (AFM) and X‐ray diffraction (XRD) results, it is observed that, using CSPSS at a lower temperature (1030 °C) significantly reduces the surface roughness and enhances the crystallinity of p‐GaN film compared to growth at 1060 °C on conventional sapphire substrate. Furthermore, the low resistivity level of 0.05 Ω cm and high hole carrier concentration of 1.57 × 1019 cm−3 in the p‐GaN have been achieved by using CSPSS at lower temperature.
Anticholinergic drugs and cognitive impairment in the elderly
Authors: Lam Y. W. Francis
Published: May 2019

Impairment of cognitive function poses a major concern in elderly patients. A cholinergic deficit that accompanies the normal aging process is thought to contribute to cognitive decline. Most anticholinergic drugs block central muscarinic receptors, which mediate cognitive effects such as attention, learning, and short‐term memory. Even though the causes of cognitive impairment in elderly patients are multifactorial, anticholinergic drugs or drugs with anticholinergic properties contribute significantly to the development of cognitive impairment in these patients.
A four‐step filtering strategy based on ultra‐high‐performance liquid chromatography coupled to quadrupole‐time‐of‐flight tandem mass spectrometry for comprehensive profiling the major chemical constituents of Akebiae Fructus
Authors: Ma Baolian , Yang Shilin , Li Junmao , Ouyang Hui , He Mingzhen , Feng Yulin , Tan Ting
Published: May 2019

Rationale

Akebiae Fructus (AF) is a traditional Chinese medicine (TCM) with antiphlogistic, analgesic, antineoplastic, diuretic, antirheumatic, antidepressant and antiobesity activities. Identification of chemical constituents from AF is helpful to discover the potential active ingredients and to control its quality.

Methods

The four‐step filtering strategy was as follows: (1) To extract the accurate mass by the different adduct ions. (2) To screen different types of the compounds using diagnostic ions. (3) By characteristic ion filtering, to confirm the substituted position and the sugar chain numbers. (4) Based on the neutral loss (NL), to identify the type of monosaccharide and the compositions of sugar chains of triterpenoid saponins and the structure of CGAs.

Results

A total of 94 compounds (85 triterpenoid saponins, 9 chlorogenic acids) were unambiguously or reasonably identified. Fifty constituents were discovered for the first time from AF. Nine types of triterpenoid saponins, including akebonoic acid (type I), norhederagenin (type II), oleanolic acid (type III), 2α,3β‐dihydroxy‐23‐oxo‐30‐norolean‐12,20(21)‐dien‐28‐oic acid (type IV), gypsogenin (type V), norarjunolic acid (type VI), hederagenin (type VII), 2α,3β‐dihydroxy‐23‐oxo‐olean‐12‐en‐28‐oic acid (type VIII), arjunolic acid (type IX), and two types of chlorogenic acid (mono‐CQA and di‐CQA), were identified in AF.

Conclusions

An ultra‐high‐performance liquid chromatography coupled to quadrupole‐time‐of‐flight tandem mass spectrometry with MSE (UPLC–QTOF‐MSE) analysis with four‐step filtering strategy was established and successfully applied to identify the chemical constituents of AF which can provide chemical support for further research and play an important role in the quality control of AF.
Pregenomic RNA: How to assist the management of chronic hepatitis B?
Authors: Wu Yongbin , Wen Jian , Xiao Weiwei , Zhang Bao
Published: May 2019

Pregenomic RNA (pgRNA) is an emerging serological marker for chronic hepatitis B virus (HBV) infection. While pgRNA is principally the template for viral proteins and viral DNAs, additional novel functions for the serum pgRNA have recently been described. These results extend for pgRNA a regulatory function in the viral life cycle and potentially a role in pathogenesis. Here, we review the diverse roles of pgRNA in HBV replication and pathogenesis, emphasizing how the unique structure of this RNA is key to its various functions. We focus in particular on the role of HBV pgRNA in guiding antiviral therapy including nucleot(s)ide analog interruption and role as a marker of cure with new curative therapies. We also briefly allude to the emerging niche for new direct‐acting or indirect‐acting antivirals targeting pgRNA.
Synergistic Amplification of Oxidative Stress–Mediated Antitumor Activity via Liposomal Dichloroacetic Acid and MOF‐Fe2+
Authors: Sun Lei , Xu Yurui , Gao Ya , Huang Xinyu , Feng Shujun , Chen Jianmei , Wang Xuekun , Guo Leilei , Li Meng , Meng Xia , Zhang Jikang , Ge Junliang , An Xueying , Ding Dang , Luo Yadong , Zhang Yu , Jiang Qing , Ning Xinghai
Published: May 2019

Cancer cells are susceptible to oxidative stress; therefore, selective elevation of intracellular reactive oxygen species (ROS) is considered as an effective antitumor treatment. Here, a liposomal formulation of dichloroacetic acid (DCA) and metal–organic framework (MOF)‐Fe2+ (MD@Lip) has been developed, which can efficiently stimulate ROS‐mediated cancer cell apoptosis in vitro and in vivo. MD@Lip can not only improve aqueous solubility of octahedral MOF‐Fe2+, but also generate an acidic microenvironment to activate a MOF‐Fe2+‐based Fenton reaction. Importantly, MD@Lip promotes DCA‐mediated mitochondrial aerobic oxidation to increase intracellular hydrogen peroxide (H2O2), which can be consequently converted to highly cytotoxic hydroxyl radicals (•OH) via MOF‐Fe2+, leading to amplification of cancer cell apoptosis. Particularly, MD@Lip can selectively accumulate in tumors, and efficiently inhibit tumor growth with minimal systemic adverse effects. Therefore, liposome‐based combination therapy of DCA and MOF‐Fe2+ provides a promising oxidative stress–associated antitumor strategy for the management of malignant tumors.
Rational Construction of 3D‐Networked Carbon Nanowalls/Diamond Supporting CuO Architecture for High‐Performance Electrochemical Biosensors
Authors: Zhai Zhaofeng , Leng Bing , Yang Nianjun , Yang Bing , Liu Lusheng , Huang Nan , Jiang Xin
Published: May 2019

Tremendous demands for highly sensitive and selective nonenzymatic electrochemical biosensors have motivated intensive research on advanced electrode materials with high electrocatalytic activity. Herein, the 3D‐networked CuO@carbon nanowalls/diamond (C/D) architecture is rationally designed, and it demonstrates wide linear range (0.5 × 10−6–4 × 10−3 m), high sensitivity (1650 µA cm−2 mm−1), and low detection limit (0.5 × 10−6 m), together with high selectivity, great long‐term stability, and good reproducibility in glucose determination. The outstanding performance of the CuO@C/D electrode can be ascribed to the synergistic effect coming from high‐electrocatalytic‐activity CuO nanoparticles and 3D‐networked conductive C/D film. The C/D film is composed of carbon nanowalls and diamond nanoplatelets; and owing to the large surface area, accessible open surfaces, and high electrical conduction, it works as an excellent transducer, greatly accelerating the mass‐ and charge‐transport kinetics of electrocatalytic reaction on the CuO biorecognition element. Besides, the vertical aligned diamond nanoplatelet scaffolds could improve structural and mechanical stability of the designed electrode in long‐term performance. The excellent CuO@C/D electrode promises potential application in practical glucose detection, and the strategy proposed here can also be extended to construct other biorecognition elements on the 3D‐networked conductive C/D transducer for various high‐performance nonenzymatic electrochemical biosensors.
Nitrogen‐Doped Porous Carbon Supported Nonprecious Metal Single‐Atom Electrocatalysts: from Synthesis to Application
Authors: Guo Jiaojiao , Huo Juanjuan , Liu Yan , Wu Wenjian , Wang Yong , Wu Minghong , Liu Hao , Wang Guoxiu
Published: May 2019

Nonprecious metal single‐atom materials have attracted extensive attention in the field of electrocatalysis due to their low cost, high reactivity, high selectivity, and high atomic utilization. However, the high surface energy of a single atom causes agglomeration during preparation and catalytic measurement, resulting in damage to the catalytic sites. The strong interaction between substrate and monoatoms is the key factor to prevent the aggregation of individual metal atoms, and the geometry and electronic structure of the catalysts can be adjusted to optimize the catalytic activity. Due to the hierarchically pores, high specific surface area, and defect effect, nitrogen‐doped porous carbon (NPC) has been widely studied as an ideal nonprecious metal single‐atom support, which synergistically enhance the electrocatalytic performance toward oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, carbon dioxide reduction reaction, and nitrogen reduction reaction with non‐noble metal single atoms. This review summarizes the controllable synthesis, characterization, theoretical calculation, and application of M (M = Co, Fe, Ni, Cu, Zn, Mo, etc.) single atoms on nitrogen‐doped porous carbon. Finally, the future development and challenges of nitrogen‐doped porous carbon supported nonprecious metal single‐atom electrocatalysts for practical commercialization are concluded.
Polyanions Enhance Conversion Reactions for Lithium/Sodium‐Ion Batteries: The Case of SbVO4 Nanoparticles on Reduced Graphene Oxide
Authors: Pan Jun , Zhang Yuchen , Li Lili , Cheng Zhenjie , Li Yanlu , Yang Xianfeng , Yang Jian , Qian Yitai
Published: May 2019

Anode materials based on redox alloying/dealloying reactions are regarded as one of the promising electrodes in Li/Na‐ion batteries. However, the enormous volume change upon cycling induces the giant structure strain, particle pulverization and then capacity decay. Here, vanadates are proposed to mitigate this concern for alloy‐type anode materials, using SbVO4 as an example. As indicated by density function theory and in situ/ex situ techniques, VO43− enhances the conversion reaction between Sb3+ and Sb, buffers the structure change induced by alloying/dealloying reactions of Sb and exhibits the electrochemical activity to Li ions. These results make SbVO4 superior to Sb, Sb2O3 and SbPO4 in the electrochemical performances, which applies both to lithium‐ion batteries and to sodium‐ion batteries. Then, the structure design and carbon composite are achieved by depositing monodispersed SbVO4 nanocrystals on reduced graphene oxides via a simple solvothermal reaction. This composite shows a good cycling stability and a high rate capability, especially in sodium‐ion batteries (73.6% after 1500 cycles at 1 A g−1, or 252 mAh g−1 at 10 A g−1). These results open the door for other alloy‐type anode materials to improve the performances.
Evaluating the effectiveness of pseudonym changing strategies for location privacy in vehicular ad‐hoc network
Authors: Saini Ikjot , Saad Sherif , Jaekel Arunita
Published: May 2019

In a vehicular ad‐hoc network, vehicles periodically broadcast safety messages to neighboring vehicles containing information about their identity, location, speed, and other relevant information. The time‐critical nature of these messages means they are typically sent without encryption, which can compromise the privacy of the vehicle/driver. The use of pseudonyms, rather than the actual identity, has been suggested as a way to implement location privacy for drivers. However, such pseudonyms need to change frequently in order to prevent vehicle tracking. A pseudonym changing strategy (PCS) determines how frequently and under which conditions a vehicle should change its pseudonym. Many different PCS have been proposed in the literature over the last decade. However, there is a lack of a systematic analysis of the performance of these techniques, using a set of well‐defined privacy metrics. In this article, we provide a thorough comparison of four main types of PCS, in terms of standard privacy metrics, and identify the advantages and limitations of each approach under different traffic conditions and attacker capabilities. The ultimate aim of this study is to help in the determination of the best PCS to use in different situations, to maximize the location privacy.