bluuebunny/crossref_metadata_2025 huggingface dataset:
Correction: Progress on particulate matter filtration technology: basic concepts, advanced materials, and performances
Authors: Liu Hui , Cao Chunyan , Huang Jianying , Chen Zhong , Chen Guoqiang , Lai Yuekun
Published: January 2020

Correction for ‘Progress on particulate matter filtration technology: basic concepts, advanced materials, and performances’ by Hui Liu, et al., Nanoscale, 2020, DOI: 10.1039/c9nr08851b.
Synthetic approaches for multiblock copolymers
Authors: Beyer Valentin P. , Kim Jungyeon , Becer C. Remzi
Published: January 2020

Multiblock copolymers (MBCs) are an emerging class of synthetic polymers that exhibit different macromolecular architectures and behaviours to those of homopolymers or di/triblock copolymers.
Self-sacrificed construction of defect-rich ZnO@ZIF-8 nanocomposites with enhanced photocurrent properties
Authors: Ma Yali , Wang Xue , Sun Xiaodong , Wang Tao , Liu Yunling , Huo Qisheng , Song Shuyan , Qiao Zhen-An
Published: January 2020

An in situ self-sacrificed template strategy was used to construct core–shell structured defective ZnO@ZIF-8 nanocomposites with enhanced photocurrent properties.
DEEPScreen: high performance drug–target interaction prediction with convolutional neural networks using 2-D structural compound representations
Authors: Rifaioglu Ahmet Sureyya , Nalbat Esra , Atalay Volkan , Martin Maria Jesus , Cetin-Atalay Rengul , Doğan Tunca
Published: January 2020

The DEEPScreen system is composed of 704 target protein specific prediction models, each independently trained using experimental bioactivity measurements against many drug candidate small molecules, and optimized according to the binding properties of the target proteins.
Copper-catalyzed enantioselective arylalkynylation of alkenes
Authors: Lei Guangyue , Zhang Hanwen , Chen Bin , Xu Meichen , Zhang Guozhu
Published: January 2020

Enantioselective aryl and alkynylation of activated/nonactivated alkenes.
(Homo)polymer-mediated colloidal stability of micellar solutions
Authors: González García Álvaro , Ianiro Alessandro , Beljon Roos , Leermakers Frans A. M. , Tuinier Remco
Published: January 2020

Shifts in the micelle–unimer equilibrium due to added compounds affect the colloidal stability of micelles.
Correction: Thermally induced top-down nanostructuring for the synthesis of a core/shell-structured CoO/CoSx electrocatalyst
Authors: Kim Min Soo , Abbas Muhammad Awais , Thota Raju , Bang Jin Ho
Published: January 2020

Correction for ‘Thermally induced top-down nanostructuring for the synthesis of a core/shell-structured CoO/CoSx electrocatalyst’ by Min Soo Kim et al., J. Mater. Chem. A, 2019, 7, 26557–26565.
Correction: Solvent-free vacuum growth of oriented HKUST-1 thin films
Authors: Han Sungmin , Ciufo Ryan A. , Meyerson Melissa L. , Keitz Benjamin K. , Mullins C. Buddie
Published: January 2020

Correction for ‘Solvent-free vacuum growth of oriented HKUST-1 thin films’ by Sungmin Han et al., J. Mater. Chem. A, 2019, 7, 19396–19406.
Crystal structure of a hemerythrin-like protein from Mycobacterium kansasii and homology model of the orthologous Rv2633c protein of M. tuberculosis
Authors: Ma Zhongxin , Abendroth Jan , Buchko Garry W. , Rohde Kyle H. , Davidson Victor L.
Published: January 2020

Pathogenic and opportunistic mycobacteria have a distinct class of non-heme di-iron hemerythrin-like proteins (HLPs). The first to be isolated was the Rv2633c protein, which plays a role in infection by Mycobacterium tuberculosis (Mtb), but could not be crystallized. This work presents the first crystal structure of an ortholog of Rv2633c, the mycobacterial HLP from Mycobacterium kansasii (Mka). This structure differs from those of hemerythrins and other known HLPs. It consists of five α-helices, whereas all other HLP domains have four. In contrast with other HLPs, the HLP domain is not fused to an additional protein domain. The residues ligating and surrounding the di-iron site are also unique among HLPs. Notably, a tyrosine occupies the position normally held by one of the histidine ligands in hemerythrin. This structure was used to construct a homology model of Rv2633c. The structure of five α-helices is conserved and the di-iron site ligands are identical in Rv2633c. Two residues near the ends of helices in the Mka HLP structure are replaced with prolines in the Rv2633c model. This may account for structural perturbations that decrease the solubility of Rv2633c relative to Mka HLP. Clusters of residues that differ in charge or polarity between Rv2633c and Mka HLP that point outward from the helical core could reflect a specificity for potential differential interactions with other protein partners in vivo, which are related to function. The Mka HLP exhibited weaker catalase activity than Rv2633c. Evidence was obtained for the interaction of Mka HLP irons with nitric oxide.
The Trp triad within the V-domain of the receptor for advanced glycation end products modulates folding, stability and ligand binding
Authors: Indurthi Venkata S.K. , Jensen Jaime L. , Leclerc Estelle , Sinha Sangita , Colbert Christopher L. , Vetter Stefan W.
Published: January 2020

The receptor for advanced glycation end products (RAGE) recognizes damage-associated molecular patterns (DAMPs) and plays a critical role for the innate immune response and sterile tissue inflammation. RAGE overexpression is associated with diabetic complications, neurodegenerative diseases and certain cancers. Yet, the molecular mechanism of ligand recognition by RAGE is insufficiently understood to rationalize the binding of diverse ligands. The N-terminal V-type Ig-domain of RAGE contains a triad of tryptophan residue; Trp51, Trp61 and Trp72. The role of these three Trp residues for domain folding, stability and binding of the RAGE ligand S100B was investigated through site-directed mutagenesis, UV/VIS, CD and fluorescence spectrometry, protein–protein interaction studies, and X-ray crystallography. The data show that the Trp triad stabilizes the folded V-domain by maintaining a short helix in the structure. Mutation of any Trp residue increases the structural plasticity of the domain. Residues Trp61 and Trp72 are involved in the binding of S100B, yet they are not strictly required for S100B binding. The crystal structure of the RAGE-derived peptide W72 in complex with S100B showed that Trp72 is deeply buried in a hydrophobic depression on the S100B surface. The studies suggest that multiple binding modes between RAGE and S100B exist and point toward a not previously recognized role of the Trp residues for RAGE-ligand binding. The Trp triad of the V-domain appears to be a suitable target for novel RAGE inhibitors, either in the form of monoclonal antibodies targeting this epitope, or small organic molecules.
Considerations for Choosing Microphone Technologies for Students With Limited Useable Hearing Unilaterally
Authors: Picou Erin M. , Davis Hilary , Tharpe Anne Marie
Published: January 2020

Purpose

Current recommendations for clinical management of school-aged children with limited useable hearing unilaterally primarily focus on remote microphone systems and preferential seating. The purpose of this narrative review is to examine the existing evidence supporting these recommendations.

Method

A narrative review was conducted, focused on nonsurgical interventions for children with limited useable hearing unilaterally.

Results

Six articles were identified. Three survey studies suggest high use rates and improved academic performance with contralateral routing of signal systems. One laboratory study suggests students with hearing loss need to sit closer to the desired signal (e.g., teacher) than their peers with normal hearing to achieve similar speech recognition. Two laboratory studies suggest remote microphone systems provide consistent benefits when the microphone is located near the talker of interest, whereas contralateral routing of signal systems impairs performance in noise.

Conclusions

The discrepancy between survey studies and laboratory studies could be explained partly due to the difference between listening situations in the laboratory and in classrooms. Everyone in the classroom is a potential talker of interest, and the listening environments are often dynamic. Thus, contralateral routing of signal systems might have more potential to improve classroom communication than was suggested by the laboratory studies. Recommendations for microphone technologies should be based on the extent to which a student is struggling, where the student sits in the classroom, and where the important talkers are located. There is not one optimal recommendation for all students, but a combination of remote microphone and contralateral routing of signal systems could work for most students.

Supplemental Material

https://doi.org/10.23641/asha.9956663
Audibility-Based Hearing Aid Fitting Criteria for Children With Mild Bilateral Hearing Loss
Authors: McCreery Ryan W. , Walker Elizabeth A. , Stiles Derek J. , Spratford Meredith , Oleson Jacob J. , Lewis Dawna E.
Published: January 2020

Purpose

Because of uncertainty about the level of hearing where hearing aids should be provided to children, the goal of the current study was to develop audibility-based hearing aid candidacy criteria based on the relationship between unaided hearing and language outcomes in a group of children with hearing loss who did not wear hearing aids.

Method

Unaided hearing and language outcomes were examined for 52 children with mild-to-severe hearing losses. A group of 52 children with typical hearing matched for age, nonverbal intelligence, and socioeconomic status was included as a comparison group representing the range of optimal language outcomes. Two audibility-based criteria were considered: (a) the level of unaided hearing where unaided children with hearing loss fell below the median for children with typical hearing and (b) the level of unaided hearing where the slope of language outcomes changed significantly based on an iterative, piecewise regression modeling approach.

Results

The level of unaided audibility for children with hearing loss that was associated with differences in language development from children with typical hearing or based on the modeling approach varied across outcomes and criteria but converged at an unaided speech intelligibility index of 80.

Conclusions

Children with hearing loss who have unaided speech intelligibility index values less than 80 may be at risk for delays in language development without hearing aids. The unaided speech intelligibility index potentially could be used as a clinical criterion for hearing aid fitting candidacy for children with hearing loss.
Waveguide‐input resonant tunnelling diode mixer for THz communications
Authors: Yu X. , Ohira T. , Kim J.‐Y. , Fujita M. , Nagatsuma T.
Published: January 2020

A hollow metallic waveguide‐input resonant tunnelling diode three‐terminal mixer device based on a photonic‐crystal platform for terahertz (THz) communication applications is presented. Coherent detection was successfully demonstrated, with an increase in the sensitivity of >30 dB compared with that of direct detection. Error‐free communications with a data rate >10 Gbit/s at 0.3 THz using the developed device as a coherent THz receiver are achieved.
Design, analysis, and realisation of chipless RFID tag for orientation independent configurations
Authors: Hashmi Mohammad S. , Sharma Vijay
Published: January 2020

The architectures of two innovative compact orientation independent chipless radio frequency identification device (RFID) tags for emerging applications such as the internet of things are presented. These tags, when illuminated, generate resonant frequencies in the radar cross‐section backscattered spectrum, which are used to encode the data. These are based around L‐type resonators, which can be read from front and back using linear polarisation waves as they do not have the ground plane. The first tag design consists of L‐resonators in the lower triangular of the substrate, and thereby mutual coupling is increased as a reduction in the size. The second tag design incorporates alternate L‐resonators in both halves of the substrate and exhibits reduced mutual coupling and enhanced printing strength but with a reduction in bit density. The proposed concept is demonstrated through prototypes of 8‐bit chipless tags on Rogers substrate. These tags require very low bandwidth to encode 8‐bit and occupy a small board size of 20 mm × 20 mm, and these are considerable improvements in the development of chipless RFID.
Neglected X-ray discovered polars
Authors: Beuermann K. , Burwitz V. , Reinsch K. , Schwope A. , Thomas H.-C.
Published: January 2020

We report on the X-ray observations of the eclipsing polar HY Eri (RX J0501–0359), along with its photometric, spectrophotometric, and spectropolarimetric optical variations, collected over 30 years. With an orbital period of 2.855 h, HY Eri falls near the upper edge of the 2–3 h period gap. After 2011, the system went into a prolonged low state, continuing to accrete at a low level. We present an accurate alias-free long-term orbital ephemeris and report a highly significant period change by 10 ms that took place over the time interval from 2011 to 2018. We acquired a high-quality eclipse spectrum that shows the secondary star as a dM5–6 dwarf at a distance d = 1050 ± 110 pc. Based on phase-resolved cyclotron and Zeeman spectroscopy, we identify the white dwarf (WD) in HY Eri as a two-pole accretor with nearly opposite accretion spots of 28 and 30 MG. The Zeeman analysis of the low state spectrum reveals a complex magnetic field structure, which we fit by a multipole model. We detected narrow emission lines from the irradiated face of the secondary star, of which Mg Iλ5170 with a radial velocity amplitude of K′2 = 139 ± 10 km s−1 (90% confidence) tracks the secondary more reliably than the narrow Hα line. Based on the combined dynamical analysis and spectroscopic measurement of the angular radius of the WD, we obtain a primary mass of M1 = 0.42 ± 0.05 M⊙ (90% confidence errors), identifying it as a probable He WD or hybrid HeCO WD. The secondary is a main sequence star of M2 = 0.24 ± 0.04 M⊙ that seems to be slightly inflated. The large distance of HY Eri and the lack of similar systems suggest a very low space density of polars with low-mass primary. According to current theory, these systems are destroyed by induced runaway mass transfer, suggesting that HY Eri may be doomed to destruction. Over the last 30 years, HY Eri experienced high and low states with mass transfer rates that differed by three orders of magnitude, varying between Ṁ ≃ 10−9 M⊙ yr−1 and 10−12 M⊙ yr−1. At a galactic latitude of −26.1°, it is located about 500 pc below the galactic plane.
Near-ultraviolet detections of four dwarf nova candidates in the globular cluster 47 Tucanae
Authors: Modiano David , Parikh Aastha S. , Wijnands Rudy
Published: January 2020

We investigate near-ultraviolet variability in the Galactic globular cluster (GC) 47 Tucanae (47 Tuc). This work was undertaken within the GC sub-project of the Transient UV Objects project, a programme which aims to find and study transient and strongly variable UV sources. Globular clusters are ideal targets for transient searches because of their high stellar densities and large populations of variable systems. Using all 75 archival observations of 47 Tuc obtained with the UV/optical telescope (UVOT) aboard theNeil Gehrels Swiftobservatory with theuvm2filter, we searched for UV variability using a specialised pipeline which utilises difference image analysis. We found four clear transients, hereafter SW1–4, with positions consistent with those of known cataclysmic variables (CVs) or CV candidates identified previously usingHubbleSpace Telescope observations. All four sources exhibit significant outbursts, likely brightening by several orders of magnitude. Based on the inferred outburst properties and the association with known CVs, we tentatively identify the UV transients as CV-dwarf novae (DNe). Two DNe have been previously observed in 47 Tuc: V2, which has a position consistent with that of SW4; and AKO 9, which was not in outburst during any of the UVOT observations. We thus increase the known number of DNe in 47 Tuc to 5 and the total number of detected DNe in all Galactic GCs combined from 14 to 17. We discuss our results in the context of the apparent scarcity of DNe in GCs. We suggest that the likely cause is observational biases, such as limited sensitivity due to the high background from unresolved stars in the GC and limited angular resolution of the telescopes used. We additionally detected one strongly variable source in 47 Tuc, which could be identified as the known RR Lyrae star HV 810. We found its period to have significantly increased with respect to that measured from data taken in 1988.
Perception de la verticale en présence d’indices d’orientation visuels ou sonores : vers une dépendance allocentrée ?
Authors: Chomienne Loïc , Goulon Cédric , Parseihian Gaëtan , Bringoux Lionel
Published: January 2020

L’étude de la perception de la verticale initiée par Witkin et Asch (1948) a abouti au concept de dépendance à l’égard du champ, distinguant les individus dans leur propension à être influencés par l’inclinaison d’un cadre visuel sur le jugement de la direction gravitaire (i.e., verticale subjective [VS]). Depuis, cette dépendance est souvent considérée comme révélatrice d’une sensibilité préférentielle aux informations visuelles par rapport à d’autres modalités sensorielles (e.g., vestibulaires ou somesthésiques). Ce travail pilote vise à reconsidérer la notion de dépendance à l’égard du champ dans la perception spatiale. Nous faisons l’hypothèse que des informations d’orientation issues d’un même cadre de référence centré sur l’environnement (i.e., référentiel allocentré) puissent conduire à une distinction comparable entre participants, quelle que soit la modalité sensorielle considérée. Face à deux scènes allocentrées (visuelle et sonore), 23 participants ont été testés sur une tâche d’ajustement de la VS. Nos résultats montrent une forte corrélation entre les ajustements dans les deux conditions sensorielles où la scène allocentrée était inclinée. Ceci suggère que les individus peuvent se différencier dans le traitement des informations spatiales issues d’un même cadre de référence, et ce de la même façon quelle que soit la modalité sensorielle permettant de relayer ces informations.
Was tun bei Hämaturie? – Schritt für Schritt
Authors: Tratz Florian , Reich Oliver , Cohen Clemens David
Published: January 2020

Hematuria is a common clinical finding and has a wide spectrum of possible causes. Erythrocytes can originate from any part of the genitourinary tract. An urine dipstick test is the first step in diagnostic approach. Medical history may help to narrow down the range of causes: arterial hypertension or a family history of renal disease may indicate a renal disease. Risk factors for an urinary tract malignoma point to an urological origin. If the microscopy shows more than 5 % acanthocytes in the urine sediment, a glomerular cause can be assumed. Normal erythrocytes suggest a non-glomerular cause. A nephrologist should be consulted if urine sediment microscopy and other clinical features (e. g. clinically relevant proteinuria, elevated serum creatinine) indicate a renal disease. In this case, a renal biopsy should be considered to confirm the diagnosis of glomerulopathy and to develop a treatment plan. If an urological pathology is suspected, sonography should be complemented by a multi-phasic computed tomography. Based on the imaging results, a retrograde ureteroscopy should be considered. Repeated urinalysis on an annual basis for two consecutive years is recommended, if no diagnosis can be established.
Lyme-Borreliose: Kutane und neurologische Manifestationen, Falldefinitionen und Therapie
Authors: Scheerer Cora , Dersch Rick , Huppertz Hans-Iko , Hofmann Heidelore
Published: January 2020

Lyme borreliosis is the most common zoonosis in Germany with an incidence of up to 138/100 000. More than 90 % of all cases show dermatological manifestations. Early manifestations are erythema migrans, multiple erythemata migrantia, and (less frequently) borrelial lymphocytoma. A typical late manifestation is acrodermatitis chronica atrophicans. Lyme neuroborreliosis is much less common with an incidence of about 0.8/100 000 inhabitants in Germany. Bannwarth’s syndrome (painful radiculoneuritis) is the most common manifestation of Lyme neuroborreliosis in adults followed by meningitis. International case definitions exist regarding the likelihood of Lyme neuroborreliosis on the basis of diagnostic test results. A CSF analysis should be performed in patients with suspected Lyme neuroborreliosis. The first line treatment for dermatological manifestations of Lyme borreliosis is doxycycline, in children and pregnant women amoxicillin. Doxycycline and beta-lactam antibiotics show similar efficacy regarding neurological symptoms and adverse effects for treatment of neurological manifestations. Treatment duration for early manifestations is 10 to 14 days, in Lyme neuroborreliosis it should not exceed 21 days. All manifestations, also Lyme neuroborreliosis, usually show a favourable prognosis after antibiotic treatment. Antibiotic treatment does not show any efficacy in patients with unspecific symptoms and concurrent positive anti-borrelial serology.
Lyme-Borreliose: Serologische und mikrobiologische Diagnostik und Differenzialdiagnostik
Authors: Fingerle Volker , Sing Andreas
Published: January 2020

Lyme borreliosis caused by at least six Borrelia burgdorferi species, is the most important tick-borne disease in the northern hemisphere. With a wide spectrum of possible symptoms, the microbiological diagnosis of this disease is associated with a wide variety of ideas, divergent approaches and much uncertainty. The aim of the article is to introduce the treating physicians to a meaningful microbiological diagnostic procedure. Most important messages include that (I) the suspected diagnosis of Lyme borreliosis is first based on anamnestic data and clinical symptoms (compare “case definitions”) which is substantiated by microbiological examinations; (II) microbiological diagnostics – primarily antibody detection, downstream PCR and culture – are only indicated if there are indicative symptoms, with typical erythema migrans not requiring microbiological diagnostics; (III) keep in mind: The more unspecific the symptoms are the lower the positive and the higher the negative predictive value of microbiological testing; (IV) serological diagnosis should follow a two-step procedure: a sensitive ELISA as first step, if reactive followed by immunoblot (IgM and IgG). Detection rates are ca. 50 % in localized, 70– > 90 % in disseminated early and nearly 100 % (only IgG relevant) in late disease; (V) in the immunoblot early forms of disease show a narrow band spectrum, late forms show a broad spectrum; (VI) methods that are not recommended for diagnostic purposes include lymphocyte activation or transformation tests (LTT, MELISA, ELISPOT), PCR or antigen detection from urine or blood, lymphocyte subpopulations, or direct detection of borreliae from patient material using dark field- or focus floating microscopy.
Orientierung in der medizinischen Forschung
Authors: Jassoy Christian
Published: January 2020

Education of medical students requires teaching students how to navigate in the broad field of medical research. The objective of this article is to provide an overview about medical research and to show how to denote a medical study in a concise fashion. Medical research can be classified into categories according to the object of investigation. Examples for medical research categories are therapeutic, diagnostic and prognostic studies, epidemiological studies, animal and in vitro studies etc. Each research category uses a specific set of study types with names such as cross-sectional study, case-control study etc. The article describes the principles of the study types. Together, research category and study type briefly describe the design of a medical study.
Endoscopic septotomy as a treatment for leaks after sleeve gastrectomy
Authors: Diaz Ramon , Welsh Leonard K. , Perez Juan Esteban , Narvaez Andres , Davalos Gerardo , Portenier Dana , Guerron A. Daniel
Published: January 2020

Background and study aims Sleeve gastrectomy (LSG) is the most commonly performed bariatric procedure in the world. Leaks are the most feared complications after this procedure. Endoscopic septotomy has been described as a resolution technique that could be useful in the setting of late and chronic leaks. We present our experience in the management of gastric leaks with this advanced endoscopic technique.

Patients and methods Retrospective review of patients who have been admitted to our hospital from January 2016 to December 2018.

Results Five patients were found. All had their index surgery in outside hospitals. The average age was 51 years (range 40 – 69), and four patients were female. Mean time from LSG to leak presentation was 15 days (range 7 – 25). Mean time from leak presentation to septotomy procedure was 61 days (range 21 – 110). All patients were treated with sleeve dilatation before septotomy using endoscopic achalasia balloons. Mean procedure time was 79 minutes (range 55 – 125). Success was achieved in 80 % of patients, and no complications related to the procedure were identified. One patient underwent total gastrectomy for definitive management. Mean follow-up time was 14.25 months (range 6 – 26), and the average time for fistula closure was 60.25 days.

Conclusion Endoscopic septotomy is safe and effective for management of chronic leaks after LSG. Associated non-selective dilatation may be a crucial step to allow distal patency and axis rectification for appropriate leak closure.
A rare case of perivascular epithelioid cell tumor (PEComa) of the pancreas diagnosed by endoscopic ultrasound
Authors: Ulrich J. D. , Specht K. , Schlitter A. M. , Ceyhan G. O. , Quante M. , Schmid R. M. , Schlag C.
Published: January 2020

A 49-year-old woman consulted her general practitioner (GP) regarding epigastric pain that she had experienced for 2 months. Physical examination and laboratory results were unremarkable. An abdominal ultrasound indicated a solid pancreatic tumor, which was confirmed on subsequent CT and MRI. Endoscopic ultrasound (EUS) showed a well-defined heterogeneous, predominantly hypoechoic mass in the pancreatic body, so a neuroendocrine tumor (NET) was suspected. However, EUS-guided fine-needle aspiration (EUS-FNA) was performed and based on (immuno-)histochemical findings, the extremely rare diagnosis of a perivascular epithelioid cell tumor (PEComa) of the pancreas was made. Due to the malignant potential of pancreatic PEComas, laparoscopic left-sided pancreatectomy was performed. We present a case diagnosed by preoperative EUS-FNA highlighting the clinical and endosonographic features which help to distinguish it from its most important differential diagnosis, neuroendocrine tumors (NETs) of the pancreas.
Gram-Scale Synthesis of the Co(nmp)2 Catalyst to Prepare trans-2,5-Disubstituted Tetrahydrofurans by the Aerobic Oxidative Cyclization of Pent-4-en-1-ols
Authors: Morra Barbora , Morra Nicholas A. , MacDonald Daniel G. , Pagenkopf Brian L.
Published: January 2020

Co(nmp)2 is an efficient catalyst for the aerobic oxidative cyclization of pent-4-en-1-ols to give 5-hydroxymethyl trans-tetrahydrofurans (THFs) as single diastereomers in high yield. The trans-THF pharmacophore is of interest because it is found in many biologically active natural products. The three-step synthesis of Co(nmp)2 described here gives the catalyst as a fine powder in 80–85% overall yield on 10-gram scale. The use of the catalyst in a representative oxidative cyclization is also described.
Recent Advances in Radical Nitration Using tert-Butyl Nitrite
Authors: Song Si-Zhe , Dong Youren , Ge Guo-Ping , Li Qiang , Wei Wen-Ting
Published: January 2020

Nitro compounds serve as valuable intermediates for pharmaceuticals, agrochemicals, dyes, and polymers. In recent years, radical nitration using tert-butyl nitrite (t-BuONO) has attracted wide attention and desirable progress has been made. On the one hand, t-BuONO is a potential active nitro radical source and can react with various functional groups. On the other hand, as a green and novel nitration reagent, t-BuONO has relatively low price and can easily produce a radical under mild conditions, which undoubtedly provides a simple and efficient way for nitration reactions. To date, some important reviews are available that summarize the synthesis of nitro compounds. To the best of our knowledge, however, there is still no review that exclusively discusses the synthesis of nitro compounds using t-BuONO through a radical strategy. Therefore, this review aims to highlight the recent advances in radical nitration using t-BuONO as nitration reagent. The main progress in this area has been presented according to the type of reaction substrates. Special attention has been paid discussion of the reaction mechanisms and selected examples of substrates have been given. We hope this paper will be a useful reference and inspiration for those who are exploring the synthesis of nitro compounds using t-BuONO.

1 Introduction

2 Radical Nitration of Alkenes

3 Radical Nitration of Aromatics

4 Radical Nitration of Alkynes

5 Radical Nitration of 1,n-Enynes

6 Radical Nitration of Alkanes

7 Summary and Perspective
On the transferability of ion parameters to the TIP4P/2005 water model using molecular dynamics simulations
Authors: Döpke Max F. , Moultos Othonas A. , Hartkamp Remco
Published: January 2020

Countless molecular dynamics studies have relied on available ion and water force field parameters to model aqueous electrolyte solutions. The TIP4P/2005 model has proven itself to be among the best rigid water force fields, whereas many of the most successful ion parameters were optimized in combination with SPC/E, TIP3P, or TIP4P/Ew water. Many researchers have combined these ions with TIP4P/2005, hoping to leverage the strengths of both parameter sets. To assess if this widely used approach is justified and to provide a guide in selecting ion parameters, we investigated the transferability of various commonly used monovalent and multivalent ion parameters to the TIP4P/2005 water model. The transferability is evaluated in terms of ion hydration free energy, hydration radius, coordination number, and self-diffusion coefficient at infinite dilution. For selected ion parameters, we also investigated density, ion pairing, chemical potential, and mean ionic activity coefficients at finite concentrations. We found that not all ions are equally transferable to TIP4P/2005 without compromising their performance. In particular, ions optimized for TIP3P water were found to be poorly transferable to TIP4P/2005, whereas ions optimized for TIP4P/Ew water provided nearly perfect transferability. The latter ions also showed good overall agreement with experimental values. The one exception is that no combination of ion parameters and water model considered here was found to accurately reproduce experimental self-diffusion coefficients. Additionally, we found that cations optimized for SPC/E and TIP3P water displayed consistent underpredictions in the hydration free energy, whereas anions consistently overpredicted the hydration free energy.
Asymmetry effects driving secondary instabilities in two-dimensional collisionless magnetic reconnection
Authors: Grasso D. , Borgogno D. , Tassi E. , Perona A.
Published: January 2020

In the framework of the studies on magnetic reconnection, much interest has been recently devoted to asymmetric magnetic configurations, which can naturally be found in solar and astrophysical environments and in laboratory plasmas. Several aspects of this problem have been investigated, mainly in a two-dimensional geometry and by means of particle-in-cell (PIC) simulations. Still, there are open questions concerning the onset and the effects of secondary instabilities in the nonlinear phase of an asymmetric reconnection process. In this work, we focus on the conditions that lead to the appearance of the Kelvin-Helmholtz instability following an asymmetric reconnection event in a collisionless plasma. This investigation is carried out by means of two-dimensional numerical simulations based on a reduced fluid model assuming a strong guide field. We show that, unlike the symmetric case, in the presence of asymmetry, a Kelvin-Helmholtz-like instability can develop also for a finite equilibrium electron temperature. In particular, simulations indicate the formation of steep velocity gradients, which drive the instability, when the resonant surface of the equilibrium magnetic field is located sufficiently far from the peak of the equilibrium current density. Moreover, a qualitative analysis of the vorticity dynamics shows that the turbulent behavior induced by the secondary instability not only is confined inside the island but can also affect the plasma outside the separatrices. The comparison between simulations carried out with an adiabatic closure and a Landau-fluid closure for the electron fluid indicates that the latter inhibits the secondary instability by smoothing velocity gradients.
Microstructural and optical emission properties of diamond multiply twinned particles
Authors: Lebedev Vadim , Yoshikawa Taro , Schreyvogel Christoph , Kirste Lutz , Weippert Jürgen , Kunzer Michael , Graff Andreas , Ambacher Oliver
Published: January 2020

Multiply twinned particles (MTPs) are fascinating crystallographic entities with a number of controllable properties originating from their symmetry and cyclic structure. In the focus of our studies are diamond MTPs hosting optically active defects—objects demonstrating high application potential for emerging optoelectronic and quantum devices. In this work, we discuss the growth mechanisms along with the microstructural and optical properties of the MTPs aggregating a high-density of “silicon-vacancy” complexes on the specific crystal irregularities. It is demonstrated that the silicon impurities incite a rapid growth of MTPs via intensive formation of penetration twins on {100} facets of regular octahedral grains. We also show that the zero-phonon-line emission from the Si color centers embedded in the twin boundaries dominates in photo- and electroluminescence spectra of the MTP-based light-emitting devices defining their steady-state optical properties.
Tuning the structural, optical, local work function and field emission properties of molybdenum oxide thin films with oxygen partial pressures
Authors: Maiti Paramita , Singh Ranveer , Sundaravel B. , Mitra Arijit , Satyam Parlapalli V.
Published: January 2020

We report a simple method involving optimization of oxygen partial pressure (OPP) in the after-growth annealing process of MoOx nanostructured thin films that results in a better field emitter with a low turn-on field and a high field enhancement factor. A ≈250 nm thick molybdenum oxide thin film has been synthesized on Si(100) substrates by the physical vapor deposition technique. The as-deposited thin films are annealed at 600 °C for 30 min in different OPPs, such as ≈2.1 × 10−9 Pa, ≈2.1 × 10−1 Pa, and ≈2.1 × 104 Pa. The effect of postannealing on the morphology, crystal structure, stoichiometry, elemental concentration, optical and local work function of the samples has been investigated using scanning electron microscopy, atomic force microscopy, resonant Rutherford backscattering spectrometry, and X-ray diffraction methods. As-deposited amorphous thin films transformed to granular MoO2 and layeredlike α-MoO3 nanostructures after annealing at 600 °C for 30 min in the OPP of ≈2.1 × 10−9 Pa and ≈2.1 × 104 Pa, respectively. The optical bandgap and the local work function are increased from 2.60 eV to 3.22 eV and 5.12 eV to 5.76 eV, whereas the field emission turn-on field is decreased from 6.6 V/μm to 4.7 V/μm for 10 μA/cm2 with increasing OPP from ≈2.1 × 10−9 Pa to ≈2.1 × 104 Pa.
Response to “Comment on ‘Ion velocity analysis of rotating structures in a magnetic linear plasma device’” [Phys. Plasmas 27, 014701 (2020)]
Authors: Claire N. , Escarguel A. , Rebont C. , Doveil F.
Published: January 2020

We thank Th. Pierre for his comments. The aim of our essentially experimental paper was to trigger new discussions about the comparison between m=1, m=2 instabilities in linear magnetized plasma. We are glad that this is the case.
Dissociative recombination of N2H+ ions with electrons in the temperature range of 80–350 K
Authors: Shapko Dmytro , Dohnal Petr , Kassayová Miroslava , Kálosi Ábel , Rednyk Serhiy , Roučka Štěpán , Plašil Radek , Augustovičová Lucie D. , Johnsen Rainer , Špirko Vladimír , Glosík Juraj
Published: January 2020

Recombination of N2H+ ions with electrons was studied using a stationary afterglow with a cavity ring-down spectrometer. We probed in situ the time evolutions of number densities of different rotational and vibrational states of recombining N2H+ ions and determined the thermal recombination rate coefficients for N2H+ in the temperature range of 80–350 K. The newly calculated vibrational transition moments of N2H+ are used to explain the different values of recombination rate coefficients obtained in some of the previous studies. No statistically significant dependence of the measured recombination rate coefficient on the buffer gas number density was observed.
Fingering regimes in unstable miscible displacements
Authors: Abdul Hamid S. A. , Muggeridge A. H.
Published: January 2020

We study the life-cycle of miscible fingering, from the early fingering initiation, through their growth and nonlinear interactions to their decay to a single finger at late times. Dimensionless analysis is used to relate the number of fingers, the nature of their nonlinear interactions (spreading, coalescence, tip splitting), and their eventual decay to the viscosity ratio, transverse Peclet number, and anisotropic dispersion. We show that the initial number of fingers that grow is approximately half that predicted by analytical solutions that neglect the impact of longitudinal diffusion smearing the interface between the injected solvent and the displaced fluid. The growth rates of these fingers are also approximately one quarter that predicted by these analyses. Nonetheless, we find that the dynamics of finger interactions over time can be scaled using the most dangerous wavenumber and associated growth rate determined from linear stability analysis. This subsequently allows us to provide a relationship that can be used to estimate when predict when the late time, single finger regime will occur.
Improving multipole magnets and background vacuum conditions on electron cyclotron resonance ion sources
Authors: Harisaki Shuhei , Onishi Koji , Hamada Kouta , Takeda Tatsuto , Okumura Kazuki , Omori Takayuki , Kubo Wataru , Ishihara Masaki , Kato Yushi
Published: January 2020

Electron cyclotron resonance ion sources (ECRISs) are used in various fields such as accelerator physics, engineering, cancer therapy, and ion engines in the satellite. We are aiming to improve the production of multicharged ions efficiently at the point of view from the length of multipole magnets and vacuum conditions in the ECRIS. The diameter of the connection pipe between the main chamber and diffusion pump was made larger to improve vacuum conductance. Moreover, the length of multipole magnets with the direction along the geometrical axis in the ECRIS was extended. The effects of these improvements are investigated experimentally to measure the pressure in the vacuum chamber, beam intensity, charge state distributions of extracted ion beams, and plasma parameters. The purity of extracted ion beams and magnetic confinement have been enhanced. These results are expected to have positive effects on the production of various species and synthesized ion beams, e.g., production of iron endohedral fullerene in the future experiments in the ECRIS.
Hydrogen ion beam transport in an energy range lower than 50 eV: Ion beam species
Authors: Ikemoto Fumiya , Yamada Ippei , Kasuya Toshiro , Kinsho Michikazu , Wada Motoi
Published: January 2020

Low energy beam transport in the energy range below 50 eV is studied using a compact ion source with a high temperature tungsten cathode that can be put into a vacuum system. A 2.6 cm diameter, 5.2 cm long compact ion source successfully produced more than 2.4 nA beam of H2+ ions at 50 eV beam energy. The source also supplied a stable beam of H3+ ions at 2.5 eV energy with more than 100 pA mass-separated current. The inside wall of the ion source was covered by thin sheets of titanium, nickel, and molybdenum to see if the species composition of the ion beam can be controlled by changing the ion source wall material. Usually, the H2+ ion peak was the highest in the mass spectrum, and the H2+ ion ratio (H2+/Hn+) was measured for a source operation with hydrogen gas. The ion species ratio drifted against time, and Mo showed the most stable ion ratio.
Low-charge-state ion production by a laser ion source for the TIARA ion implanter
Authors: Yamada K. , Kashiwagi H.
Published: January 2020

Ion implanters require various kinds of heavy-ion beams in low-charge states for material science experiments. For this purpose, a laser ion source has been developed for the ion implanter at Takasaki Ion Accelerators for Advanced Radiation Application. In this study, we investigated the particle number of ions per laser pulse for each charge state in the laser-produced carbon plasma. In the experiment, the carbon plasma was generated from a graphite target using a Nd:YAG laser (1064 nm wavelength, 5 ns pulse width) at a laser energy of 37.5 mJ, 28.3 mJ, or 15.6 mJ. The particle number of ions in the plasma was evaluated from the time-integrated value of each ion-charge-state’s current signal by placing the focusing lens at various positions. We found that the particle number of carbon ions was the highest for singly charged ions at all laser energies, with particle number in the order of 1010 ions obtained at a 1-m distance from the target surface.
Interactions of metal phthalocyanines with Stone-Wales defects on single-walled carbon nanotubes: A theoretical study
Authors: Bolivar-Pineda Lina M. , Basiuk Vladimir A.
Published: January 2020

A density functional theory (DFT) analysis of the influence of Stone-Wales (SW) defect incorporated into an armchair and zigzag single-walled carbon nanotube (SWCNT) models (ANT and ZNT, respectively) functionalized noncovalently with unsubstituted nickel(II) and cobalt(II) phthalocyanines (MPcs, where M = Ni2+, Co2+) as representative Pcs was performed at the PBE-D/DNP level of theory. The data obtained (bonding and frontier orbital energies, geometries, charge and spin distribution, etc.) were compared with the DFT results for similar systems based on defect-free nanotube models. SW defect was incorporated into each nanotube model in different orientations with respect to SWCNT axis, depending on whether the (7,7) junction is tilted (ANT_SW-T and ZNT_SW-T models), parallel (ANT_SW-P), or perpendicular (ZNT_SW-P) with respect to the SWCNT axis. The formation energy of SW defect-containing SWCNTs depends on the defect orientation and nanotube chirality, decreasing in the order of ANT_SW-P > ZNT_SW-T > ANT_SW_T > ZNT_SW-P; in all cases, HOMO-LUMO gap narrowing was observed. Phthalocyanine molecules in MPc + SWCNT_SW complexes undergo strong bending distortion in order to increase the area of their contact with the nanotube sidewall. As compared to NiPc and CoPc dyads with defect-free nanotubes, formation energy ΔE decreased (that is, bonding strength increased) for three complexes, for four complexes an opposite effect was found, and in one case the variation was negligible. For most dyads, gap narrowing was observed, as compared to both defect-free complexes and SW defect-containing isolated nanotube models.
Molecular dynamics study of thermal transport in single-layer silicon carbide nanoribbons
Authors: Islam Md. Sherajul , Islam A. S. M. Jannatul , Mahamud Orin , Saha Arnab , Ferdous Naim , Park Jeongwon , Hashimoto Akihiro
Published: January 2020

Aiming to solve the heat dissipation problem of next generation energy-efficient nanoelectronics, we have explored the thermal transport behavior of monolayer silicon carbide nanoribbons (SiCNRs) using equilibrium molecular dynamics simulation based on Green-Kubo formalism. Our comprehensive analysis includes the calculation of thermal conductivity both for armchair and zigzag edged SiCNRs as a function of temperature, ribbon width, and length. At a temperature of 300 K, the thermal conductivity of 10 nm × 3 nm SiCNRs is found to be 23.92 ± 4.01 W/m K and 26.26 ± 4.18 W/m K for the armchair and zigzag direction, respectively. With the increase in temperature and length, a decreasing behavior of the thermal conductivity is observed for both directions of the SiCNRs, while the thermal conductivity increases with the increase in the ribbon width. Besides, to explain the size-dependent thermal transport phenomena, the acoustic phonon density of states is calculated using velocity autocorrelation of atoms. The variation of different low-frequency phonon modes validates the explored thermal conductivity at varying widths and lengths. These results would provide insight into and inspiration to design next-generation nanoelectronics with enhanced thermal efficiency using novel SiCNRs.
Transmission of intense laser light through foil with subwavelength-holes array
Authors: Lu Sidailuo , Sheng Zheng-Mao , Yu Ming-Young
Published: January 2020

Transmission of intense laser light through a thin foil containing multiple near- or sub-wavelength holes is investigated using electromagnetic particle-in-cell simulation. It is found that the intensity of transmitted light neither increased with hole size nor decreased with the hole separation distance monotonically, but there are several maximum transmissivities with optimized parameters. Despite the nonlinear light-matter interaction that can accelerate and expel electrons and, eventually, also ions in the foil, the dependence of the transmitted light intensity on the foil and hole properties is similar to that of extraordinary optical transmission in the nondestructive interaction of weak light of the same profile with thin multiholed metal foils, provided that the ratio width:length:period of the hole dimensions is similar.
Coarse-grained simulations of diffusion controlled release of drugs from neutral nanogels: Effect of excluded volume interactions
Authors: Maroto-Centeno José Alberto , Quesada-Pérez Manuel
Published: January 2020

The primary goal of this work is to assess the effect of excluded volume interactions on the diffusion controlled release of drug molecules from a spherical, neutral, inert, and cross-linked device of nanometric size. To this end, coarse-grained simulations of the release process were performed. In this way, the inner structure and topology of the polymer network can be explicitly taken into account as well. Our in silico experiments reveal that the boundary condition of constant surface concentration is not appropriate for nanogels. In particular, the predictions based on the perfect sink condition clearly overestimate the fraction of drug released. In addition, these simulations provide values for the release exponent that depends on both the diameter of drug molecules and the number of drug molecules loaded in the matrix, which clearly contrasts with the classical prediction of a constant release exponent. Consequently, the widely used classification of drug release mechanisms based on this kinetic exponent must be extended to include new situations.