bluuebunny/crossref_metadata_2025 huggingface dataset:
An electrostatic energy-based charge model for molecular dynamics simulation
Authors: Wang Xianwei , Yan Jinhua , Zhang Hang , Xu Zhousu , Zhang John Z. H.
Published: April 2021

The interactions of the polar chemical bonds such as C=O and N–H with an external electric field were investigated, and a linear relationship between the QM/MM interaction energies and the electric field along the chemical bond is established in the range of weak to intermediate electrical fields. The linear relationship indicates that the electrostatic interactions of a polar group with its surroundings can be described by a simple model of a dipole with constant moment under the action of an electric field. This relationship is employed to develop a general approach to generating an electrostatic energy-based charge (EEC) model for molecules containing single or multiple polar chemical bonds. Benchmark test studies of this model were carried out for (CH3)2–CO and N-methyl acetamide in explicit water, and the result shows that the EEC model gives more accurate electrostatic energies than those given by the widely used charge model based on fitting to the electrostatic potential (ESP) in direct comparison to the energies computed by the QM/MM method. The MD simulations of the electric field at the active site of ketosteroid isomerase based on EEC demonstrated that EEC gave a better representation of the electrostatic interaction in the hydrogen-bonding environment than the Amber14SB force field by comparison with experiment. The current study suggests that EEC should be better suited for molecular dynamics study of molecular systems with polar chemical bonds such as biomolecules than the widely used ESP or RESP (restrained ESP) charge models.
Temperature induced dynamics of water confined between graphene and MoS2
Authors: Bampoulis P.
Published: April 2021

Water trapped between MoS2 and graphene assumes a form of ice composed of two planar hexagonal layers with a non-tetrahedral geometry. Additional water does not wet these ice layers but forms three-dimensional droplets. Here, we have investigated the temperature induced dewetting dynamics of the confined ice and water droplets. The ice crystals gradually decrease in size with increasing substrate temperature and completely vanish at about 80 °C. Further heating to 100 °C induces changes in water droplet density, size, and shape through droplet coalescence and dissolution. However, even prolonged annealing at 100 °C does not completely dry the interface. The dewetting dynamics are controlled by the graphene cover. Thicker graphene flakes allow faster water diffusion as a consequence of the reduction of graphene’s conformity along the ice crystal’s edges, which leaves enough space for water molecules to diffuse along the ice edges and evaporate to the environment through defects in the graphene cover.
Dynamics of a pair of paramagnetic particles in shear flows under a uniform magnetic field
Authors: Zhang Jie , Rifat Hassan Md , Wang Cheng
Published: April 2021

We numerically investigated the particle–particle interaction and relative motion of a pair of equal-sized magnetic particles in simple shear and plane Poiseuille flows. Two-dimensional numerical models were created by using direct numerical simulations, which are based on the finite element method and arbitrary Lagrangian–Eulerian approach with full consideration of particle–particle, particle–magnetic field, particle–flow field interactions. The effects of direction and strength of magnetic field on the dynamics of the particles in simple shear and plane Poiseuille flows were investigated, respectively. In the simple shear flow, the presence of magnetic field can show stabilizing or destabilizing effect on the particle trajectories, depending on the direction of the magnetic field. Specifically, the particles initially located at closed trajectories moved closer and closer when the magnetic field is applied at 0°and 135°, while they moved further apart and separated when the field is applied at 90°. In the plane Poiseuille flow, the magnetic field changed the relative motion of two particles: it induced two particles to form a chain when a strong magnetic field is applied at 0°and 135°; it separated the two particles when a strong magnetic field is applied at 45°and 90°. This work offers insights toward understanding the mechanisms of particle–particle interaction in magnetorheological fluids in simple shear or plane Poiseuille flows under a uniform magnetic field.
Role of oxygen in the UV-ps laser triggered amorphization of poly-Si for Si solar cells with local passivated contacts
Authors: Schäfer Sören , Mercker Anja , Köhler Adrian , Neubert Tobias , Mettner Larissa , Wolpensinger Bettina , Mertens Verena , Peibst Robby
Published: April 2021

In recent years, poly-Si based passivated contacts elevated the conversion efficiencies of crystalline Si solar cells to levels of 26%abs due to their outstanding electrical surface passivation performance and current transport characteristics. A major associated challenge, however, is the large parasitic light absorption within the doped poly-Si, regardless if the contacts are applied on the front and/or on the rear side of the solar cell. It, therefore, might be beneficial to confine the passivated contacts to local regions underneath the metal contacts. We present an effective and flexible laser-based approach to structure the poly-Si layer after its full-area deposition. Laser pulses with a pulse duration of 9 ps and a wavelength of 355 nm trigger an amorphization of the poly-Si surface. The minimum threshold fluence for amorphization is between 89 and 129 mJ/cm2. The a-Si layer, which is laterally homogeneous and up to (33 ± 4) nm in thickness, works as an etch barrier in an alkaline solution. The most robust barrier corresponding to the maximum thickness of the a-Si layer is found for a fluence of (270 ± 30) mJ/cm2. Besides the impact of the laser fluence on the etch resistiveness of the modified poly-Si layer, we study the role of oxygen during the laser process. We find that oxygen becomes incorporated into the material for certain laser fluences, which results in a more robust etch barrier. The amount of oxygen incorporated is below 3 wt. %. Eventually, we present a phenomenological model of our findings.
Effect of thickness on metal-to-semiconductor transition in 2-dimensional TiN thin films
Authors: Roy Manosi , Mucha Nikhil Reddy , Fialkova Svitlana , Kumar Dhananjay
Published: April 2021

Titanium nitride thin films have been grown on c-plane sapphire substrates using a pulsed laser deposition technique in the thickness range of 6–45 nm. X-ray diffraction (XRD) analysis has demonstrated TiN (111) as the preferred orientation of growth on the sapphire substrates. The XRD measurements have also indicated that orientational alignment between the TiN and the sapphire improved with an increase in the TiN film thickness. A change in the resistivity behavior of the TiN thin films from metallic to semiconducting has been observed as the TiN film thickness is reduced below 15 nm. Analyzing and fitting of TiN films’ conductivity data have shown that while the Arrhenius law governs their conductivity in the temperature range of 300–350 K, conductivity values of the films follow the variable range hopping mechanism below 300 K.
Fast periodic Gaussian density fitting by range separation
Authors: Ye Hong-Zhou , Berkelbach Timothy C.
Published: April 2021

We present an efficient implementation of periodic Gaussian density fitting (GDF) using the Coulomb metric. The three-center integrals are divided into two parts by range-separating the Coulomb kernel, with the short-range part evaluated in real space and the long-range part in reciprocal space. With a few algorithmic optimizations, we show that this new method—which we call range-separated GDF (RSGDF)—scales sublinearly to linearly with the number of k-points for small to medium-sized k-point meshes that are commonly used in periodic calculations with electron correlation. Numerical results on a few three-dimensional solids show about ten-fold speedups over the previously developed GDF with little precision loss. The error introduced by RSGDF is about 10−5 Eh in the converged Hartree–Fock energy with default auxiliary basis sets and can be systematically reduced by increasing the size of the auxiliary basis with little extra work.
An interplay of excluded-volume and polymer–(co)solvent attractive interactions regulates polymer collapse in mixed solvents
Authors: Bharadwaj Swaminath , Nayar Divya , Dalgicdir Cahit , van der Vegt Nico F. A.
Published: April 2021

Cosolvent effects on the coil–globule transitions in aqueous polymer solutions are not well understood, especially in the case of amphiphilic cosolvents that preferentially adsorb on the polymer and lead to both polymer swelling and collapse. Although a predominant focus in the literature has been placed on the role of polymer–cosolvent attractive interactions, our recent work has shown that excluded-volume interactions (repulsive interactions) can drive both preferential adsorption of the cosolvent and polymer collapse via a surfactant-like mechanism. Here, we further study the role of polymer–(co)solvent attractive interactions in two kinds of polymer solutions, namely, good solvent (water)–good cosolvent (alcohol) (GSGC) and poor solvent–good cosolvent (PSGC) solutions, both of which exhibit preferential adsorption of the cosolvent and a non-monotonic change in the polymer radius of gyration with the addition of the cosolvent. Interestingly, at low concentrations, the polymer–(co)solvent energetic interactions oppose polymer collapse in the GSGC solutions and contrarily support polymer collapse in the PSGC solutions, indicating the importance of the underlying polymer chemistry. Even though the alcohol molecules are preferentially adsorbed on the polymer, the trends of the energetic interactions at low cosolvent concentrations are dominated by the polymer–water energetic interactions in both the cases. Therefore, polymer–(co)solvent energetic interactions can either reinforce or compensate the surfactant-like mechanism, and it is this interplay that drives coil-to-globule transitions in polymer solutions. These results have implications for rationalizing the cononsolvency transitions in real systems such as polyacrylamides in aqueous alcohol solutions where the understanding of microscopic driving forces is still debatable.
Modeling interactions of dsDNA inside single-walled nanotubes
Authors: Alshehri Mansoor H.
Published: April 2021

Nanotubes (NTs) have unique physicochemical properties, and therefore, they have found various applications, especially in medicine and electronics. This study models the interaction of a double-stranded deoxyribonucleic acid (dsDNA) molecule inside carbon, boron nitride, silicon, molybdenum disulphide (MoS2), and tungsten disulphide (WS2) single-walled NTs by using the Lennard-Jones potential and a continuum approach. Explicit analytical expressions for the interaction energy are obtained to determine the preferred minimum-energy position of the dsDNA molecule inside the NTs. Furthermore, the encapsulation behavior of the dsDNA molecule inside these five types of NTs is compared. The results indicate that the encapsulation of the dsDNA molecule inside the NTs depends on the NT diameter. The results also indicate that DNA can be encapsulated inside NTs for applications in biosensors, drug and gene delivery systems, and biomaterials as well as for detecting biomolecules for biotechnology and medical science applications.
Intramolecular O—H⋯S hydrogen bonding in threefold symmetry: Line broadening dynamics from ultrafast 2DIR-spectroscopy and ab initio calculations
Authors: Brünker Paul , Domenianni Luis I. , Fleck Nico , Lindner Jörg , Schiemann Olav , Vöhringer Peter
Published: April 2021

The dynamics of intramolecular hydrogen-bonding involving sulfur atoms as acceptors is studied using two-dimensional infrared (2DIR) spectroscopy. The molecular system is a tertiary alcohol whose donating hydroxy group is embedded in a hydrogen-bond potential with torsional C3-symmetry about the carbon–oxygen bond. The linear and 2DIR-spectra recorded in the OH-stretching region of the alcohol can be simulated very well using Kubo’s line shape theory based on the cumulant expansion for evaluating the linear and nonlinear optical response functions. The correlation function for OH-stretching frequency fluctuations reveals an ultrafast component decaying with a time constant of 700 fs, which is in line with the apparent decay of the center line slopes averaged over absorption and bleach/emission signals. In addition, a quasi-static inhomogeneity is detected, which prevents the 2DIR line shape to fully homogenize within the observation window of 4 ps. The experimental data were then analyzed in more detail using a full ab initio approach that merges time-dependent structural information from classical molecular dynamics (MD) simulations with an OH-stretching frequency map derived from density functional theory (DFT). The latter method was also used to obtain a complementary transition dipole map to account for non-Condon effects. The 2DIR-spectra obtained from the MD/DFT method are in good agreement with the experimental data at early waiting delays, thereby corroborating an assignment of the fast decay of the correlation function to the dynamics of hydrogen-bond breakage and formation.
GaN-based pyramidal quantum structures for micro-size light-emitting diode applications
Authors: Le Son Phuong , Hsu Chih-Wei , Martinovic Ivan , Holtz Per-Olof
Published: April 2021

GaN-based pyramidal quantum structures, InGaN nanostructures located on top of micro-sized GaN pyramids, were fabricated by selective-area growth on SiC substrates by means of hot-wall metal-organic chemical vapor deposition. Arrays of GaN-based pyramidal structures exhibit micro-size pyramids possessing high uniformity, precise hexagonal bases, and InGaN/GaN quantum-well layers with well-defined interfaces. Each pyramid comprises a p-i-n InGaN/GaN structure, which is separated from that of other pyramids by a dielectric layer, serving as a building block for micro-emitters. Moreover, interconnected micro-size light-emitting diodes (microLEDs) built on the GaN-based pyramidal quantum structures were demonstrated, resulting in well-determined electroluminescence in the near-ultraviolet regime with negligible spectral shifts at high current levels. The results elucidated the rewards for development of these light-emitting designs and their potential for microLED applications.
Evaluation of Calcium Binding Capacity of Chelating Agents in Calcium Carbonate Suspension and Effects on Calcium Distribution of Calcium Chelating Agents
Authors: Song Mingyue , Dang Leping , Wei Hongyuan
Published: April 2021

In this study, the binding capacity of calcium ions of sodium tripolyphosphate (STPP), tetrasodium pyrophosphate (TSPP), trisodium citrate (TSC), and potassium oxalate (PO) were evaluated, and the calcium distribution in the presence of STPP and TSPP in CaCl2 solutions (50 mmol L−1) were investigated. Under conditions simulating industrial toothpaste, the concentration of fluoride in calcium carbonate suspensions (30 g/50 g) was measured by ion chromatography to investigate the effects of chelating agents on calcium ions. Among all the chelating agents, STPP and TSPP have the highest retention rate of fluoride, indicating better calcium binding capacity. Preliminary studies were carried out in CaCl2 solutions to investigate the influence of concentration and pH on the chelating performance of STPP and TSPP. The distribution of free calcium, chelated calcium, and precipitated calcium in CaCl2 solution in the presence of STPP and TSPP were investigated to reveal two different calcium-chelation mechanisms and laws for STPP and TSPP. This work has a positive guiding significance for the stabilisation of calcium and fluoride in toothpaste formula.
(Mis)informed about what? What it means to be a science-literate citizen in a digital world
Authors: Howell Emily L. , Brossard Dominique
Published: April 2021

Science literacy is often held up as crucial for avoiding science-related misinformation and enabling more informed individual and collective decision-making. But research has not yet examined whether science literacy actually enables this, nor what skills it would need to encompass to do so. In this report, we address three questions to outline what it should mean to be science literate in today’s world: 1) How should we conceptualize science literacy? 2) How can we achieve this science literacy? and 3) What can we expect science literacy’s most important outcomes to be? If science literacy is to truly enable people to become and stay informed (and avoid being misinformed) on complex science issues, it requires skills that span the “lifecycle” of science information. This includes how the scientific community produces science information, how media repackage and share the information, and how individuals encounter and form opinions on this information. Science literacy, then, is best conceptualized as encompassing three dimensions of literacy spanning the lifecycle: Civic science literacy, digital media science literacy, and cognitive science literacy. Achieving such science literacy, particularly for adults, poses many challenges and will likely require a structural perspective. Digital divides, in particular, are a major structural barrier, and community literacy and building science literacy into media and science communication are promising opportunities. We end with a discussion of what some of the beneficial outcomes could be—and, as importantly, will likely not be—of science literacy that furthers informed and critical engagement with science in democratic society.
Integrins protect sensory neurons in models of paclitaxel-induced peripheral sensory neuropathy
Authors: Shin Grace Ji-eun , Pero Maria Elena , Hammond Luke A. , Burgos Anita , Kumar Atul , Galindo Samantha E. , Lucas Tanguy , Bartolini Francesca , Grueber Wesley B.
Published: April 2021

Significance

Paclitaxel is a common chemotherapeutic agent and often causes a form of sensory dysfunction termed chemotherapy-induced peripheral neuropathy (CIPN). There is no approved therapy to counteract CIPN, although the CIPN symptoms interfere with effective cancer treatment and impose long-term health and economic burdens for cancer survivors. As chemotherapy is still a first-line treatment for many patients, understanding the basis for CIPN is critical. Using complementary approaches in
Drosophila
and mouse sensory neurons, we characterized paclitaxel-induced cellular and behavioral changes. We link changes in sensory neurons with integrins, cell surface receptors critical for coupling neurons with the extracellular matrix. Altogether, we propose that altered interactions between sensory neurons and their extracellular environment are an important contributor to paclitaxel-induced peripheral neuropathy.
Measuring voluntary and policy-induced social distancing behavior during the COVID-19 pandemic
Authors: Yan Youpei , Malik Amyn A. , Bayham Jude , Fenichel Eli P. , Couzens Chandra , Omer Saad B.
Published: April 2021

Significance

Early in the US COVID-19 epidemic, Americans spent substantially more time at home to reduce cases. Disentangling voluntary from policy-induced behavioral changes is critical for governments grappling with relaxing or renewing restrictions. We estimate the number of additional reported cases that would have been needed to elicit a voluntary behavioral response equivalent to the behavioral response to policy. A substantial share of the observed behavioral response was voluntary. Stay-at-home orders increased the time people spent at home by replacing voluntary actions that likely would have emerged as cases rose. Our analysis is an initial step in answering the critical policy question as to whether fast forwarding the response provides sufficient public health benefits to justify the mandates.
Myristoylation alone is sufficient for PKA catalytic subunits to associate with the plasma membrane to regulate neuronal functions
Authors: Xiong Wei-Hong , Qin Maozhen , Zhong Haining
Published: April 2021

Significance

Myristoylation is a major type of cotranslational lipid modification to many proteins that play important roles in numerous cell biology processes. Myristoylation serves diverse roles in protein–membrane association, protein structure, protein stability, and protein–protein interaction. With regard to protein–membrane association, it is believed that myristoylation alone does not confer sufficient energy to associate a protein to the membrane unless assisted by a second membrane-affinity motif. We find that the myristoylation on the PKA catalytic subunit (PKA-C) is sufficient to associate a fraction of PKA-C molecules to the plasma membrane in neuronal dendrites in a functionally significant manner without a canonical second motif. Our results remove a conceptual constraint for understanding myristoylated proteins and their function.
Outcomes of an Interprofessional SBIRT Training Program: Knowledge Attainment and Perceived Competence for Practice
Authors: Acquavita Shauna P. , Richardson George B. , Smith Rachel , Van Loon Ruth Anne , Brehm Bonnie , Kim Karissa , Diers Tiffiny
Published: April 2021

Background

One way to address substance misuse is to train health professional students in Screening, Brief Intervention, and Referral to Treatment (SBIRT), an early intervention strategy. This study evaluated a semester-long, 50-hour elective SBIRT training that blended online coursework with interprofessional experiences. Medicine, nursing, pharmacy, and social work students completed an interprofessional standardized patient experience and completed a minimum of two interprofessional SBIRT experiences at community agencies.

Methods

We analyzed longitudinal data from 197 students using structural equation modeling to examine gains in knowledge and perceived competence, as well as to test if background variables predicted 30-day application of SBIRT knowledge and skills, 30-day satisfaction’ 12-month frequencies of care for performing SBIRT; and number of SBIRT clients/patients served directly.

Results

Overall, student SBIRT knowledge and perceived competence both increased by more than a standard deviation during the course. Students who experienced larger gains in perceived competence rated the course significantly higher in terms of relevance and usefulness and, in turn, served significantly more SBIRT clients/patients during the following year. We did not find evidence that intra-individual growth in knowledge impacted the degree to which students ultimately applied SBIRT components. Finally, students who had more previous training and experience related to substance abuse ultimately reported greater application of SBIRT knowledge and skills. Interprofessional differences included: At baseline, medicine students had significantly lower substance abuse education knowledge as compared to the other disciplines. Pharmacy and social work students were more likely to have had previous experience with motivational interviewing. Baseline perceived competence in applying SBIRT was higher in social work and nursing. Upon completion, pharmacy and medicine students had lower satisfaction with the course.

Conclusions

These findings suggest that SBIRT courses can increase knowledge and perceived competence; moreover, student background characteristics, work settings, and experiences may have important effects on learning SBIRT.
Recent and Active Problematic Substance use among Primary Care Patients: Results from the Alcohol, Smoking, and Substance Involvement Screening Test in a Multisite Study
Authors: John William S. , Zhu He , Greenblatt Lawrence H. , Wu Li-Tzy
Published: April 2021

Background

Primary care settings provide salient opportunities for identifying patients with problematic substance use and addressing unmet treatment need. The aim of this study was to examine the extent and correlates of problematic substance use by substance-specific risk categories among primary care patients to inform screening/intervention efforts.

Methods

Data were analyzed from 2000 adult primary care patients aged ≥18 years (56% female) across 5 clinics in the eastern U.S. Participants completed the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST). Prevalence and ASSIST-defined risk-level of tobacco use, alcohol use, and nonmedical/illicit drug use was examined. Multinomial logistic regression models analyzed the demographic correlates of substance use risk-levels.

Results

Among the total sample, the prevalence of any past 3-month use was 53.9% for alcohol, 42.0% for tobacco, 24.2% for any illicit/Rx drug, and 5.3% for opioids; the prevalence of ASSIST-defined moderate/high-risk use was 45.1% for tobacco, 29.0% for any illicit/Rx drug, 14.2% for alcohol, and 9.1% for opioids. Differences in the extent and risk-levels of substance use by sex, race/ethnicity, and age group were observed. Adjusted logistic regression showed that male sex, white race, not being married, and having less education were associated with increased odds of moderate/high-risk use scores for each substance category; older ages (versus ages 18–25 years) were associated with increased odds of moderate/high-risk opioid use.

Conclusions

Intervention need for problematic substance use was prevalent in this sample. Providers should maintain awareness and screen for problematic substance use more consistently in identified high risk populations.
Covid 19 Impact Screening of Patients Undergoing Medication Treatment for Opioid use Disorder
Authors: Manzardo Ann M. , Sethi Roopa
Published: April 2021

Background

Populations with addiction are considered at-risk for both medical and financial effects of the COVID19 outbreak. Patients receiving medication treatment for opioid use disorder (MOUD) were screened to assess need, vulnerability factors and potential clinical impact of the pandemic for referral and allocation of resources.

Methods

A 31-item quality improvement survey of COVID19-related factors (e.g. engagement in social distancing, food and financial security) and clinical benchmarks of anxiety, craving, and treatment response was administered between March 24 and April 29, 2020. Anonymized data were compiled for study. Frequencies and means were evaluated for gender, age and financial effects on anxiety and craving ratings.

Results

A total of 200 ( N = 117 male; N = 80 female; N = 1 transgender) patients (age 42 ± 13 years) were screened. Medical risk factors known to predict severe COVID19 reactions reported in 33% of patients did not contribute significantly to distress. While 95% of patients reported stable food and housing, personal financial and employment instability reported in 40% of patients was associated with significantly increased anxiety and craving rating, particularly for women.

Conclusions

Financial ramifications of the COVID19 pandemic were the most salient concerns reported by patients engaged in MOUD in the early phases of the outbreak, particularly for women.
Article Commentary: It Will End in Tiers: A Strategy to Include “Dabblers” in the Buprenorphine Workforce after the X-Waiver
Authors: Saloner Brendan , Andraka Christou Barbara , Gordon Adam J. , Stein Bradley D.
Published: April 2021

Buprenorphine is one of the gold standard medication treatments for opioid use disorder (OUD), with proven effectiveness in preventing overdose, increasing abstinence, and improving quality of life. In the United States, buprenorphine can be legally prescribed and administered in office-based settings from clinicians who are specially credentialed to provide that care under the X-waiver. We believe the X-waiver will ultimately be repealed, but there is a need for a variety of strategies to create a new treatment system after the X-waiver. Building a new tier of treatment capacity will require educational outreach, systems strategies, and enhanced payments.
Experimental study of core and edge fluctuations by reflectometry on EAST tokamak
Authors: ZHOU Zhen , ZHANG Tao , WU Mingfu , YE Kaixuan , ZHONG Fubin , HUANG Jia , GENG Kangning , LIU Yukai , LI Gongshun , XIANG Haoming , WANG Yumin , WEN Fei , LIU Sanqiu
Published: April 2021

An eight-channel poloidal correlation reflectometer (PCR) with O-mode polarization has been installed in the EAST tokamak to measure the fluctuations from core to edge. The PCR launches eight different frequency microwaves (20.4, 24.8, 33, 40, 42.4, 48, 52.6, 57.2 GHz) into the plasma from the low field side and two poloidally separated antennae are used to receive the reflected waves. As a result, the diagnostic can measure fluctuations in eight (radial)× two (poloidal) spatial positions. The diagnostic has been applied to study the core and edge pedestal fluctuations during an inter-ELM phase in H-mode plasma. This inter-ELM phase can be divided into two stages. In the first stage, a low frequency (<50 kHz) broadband fluctuation dominates in the pedestal gradient region. In the second stage, this fluctuation is strongly suppressed and quasi-coherent fluctuations (QCFs) appear. The QCF’s amplitude increases with the pedestal density gradient, implying density gradient driven instabilities. But the core fluctuations inside the pedestal show no evident changes during the inter-ELM phase.
Simple and projective correspondence functors
Authors: Bouc Serge , Thévenaz Jacques
Published: April 2021

A correspondence functor is a functor from the category of finite sets and correspondences to the category of

k
k

-modules, where

k
k

is a commutative ring. We determine exactly which simple correspondence functors are projective. We also determine which simple modules are projective for the algebra of all relations on a finite set. Moreover, we analyze the occurrence of such simple projective functors inside the correspondence functor 

F
F

associated with a finite lattice and we deduce a direct sum decomposition of 

F
F

.
Determination of Fucoxanthin in Bloom-Forming Macroalgae by HPLC–UV
Authors: Li Minlan , Feng Haozhan , Ouyang Xiaokun , Ling Junhong
Published: April 2021

Fucoxanthin is a carotenoid natural product with extensive biological activities and offers a variety of health benefits. Brown algae and diatoms are known producers of this compound as an important component of their light-harvesting complexes. Considering its important function in algal photosynthesis, we assume that the massive biomass from macroalgal blooms is potential bioresources of this compound. Accordingly, a high-performance liquid chromatography–ultra-violet (HPLC–UV) method was developed and validated for quantitation of fucoxanthin in bloom-forming macroalgal species from coastal waters of north China. The linear regression was acquired with r = 0.9991. The precisions were evaluated by intra- and inter-day tests, and the relative standard deviation (RSD) values were within the range of 0.59 and 2.30%, respectively. The recoveries for the method were observed over the range of 99.3–100.4% with RSD values < 2.6%. Our results showed that fucoxanthin occurs in all the tested algae including red and green algal species, which are not generally considered as fucoxanthin producers. Application of HPLC–time-of-flight mass spectrometry for the qualitative analysis further confirmed the production of fucoxanthin in these species. The developed method provided an insight into the potential of the macroalgal biomass commercial production of fucoxanthin.
Rapid Determination of Metronidazole and 2-Hydroxymetronidazole in Murine Blood Plasma
Authors: Zemanová Nina , Anzenbacher Pavel , Hudcovic Tomáš , Anzenbacherová Eva
Published: April 2021

Metronidazole is a drug used to treat bacterial and protozoan infections. Nowadays, it is one of the most frequently prescribed drugs worldwide. The main aim of this paper is to present a rapid, reliable and simple high-performance liquid chromatography (HPLC) method to determine metronidazole along with its primary metabolite, 2-hydroxymetronidazole, in plasma or serum using paracetamol as an internal standard. A total of 100% methanol was used to denature plasma proteins. After centrifugation, the supernatant was evaporated under nitrogen flow. The samples were dissolved in the mobile phase and injected into a Li-Chrospher RP-18 column. A total of 10 mmol/L NaH2PO4: acetonitrile (90:10, v/v) solution with a flow rate of 1 mL/min was used as the mobile phase. Metronidazole and 2-hydroxymetronidazole were detected at two different wavelengths at 320 nm and 311 nm, respectively. The method is characterized by high precision (relative standard deviation % < 6). The method was used for the determination of metronidazole and 2-hydroxymetronidazole in murine blood using small amounts of plasma (≤100 μL).
Obstructive sleep apnoea testing and management in atrial fibrillation patients: a joint survey by the European Heart Rhythm Association (EHRA) and the Association of Cardiovascular Nurses and Allied Professions (ACNAP)
Authors: Desteghe Lien , Hendriks Jeroen M L , Heidbuchel Hein , Potpara Tatjana S , Lee Geraldine A , Linz Dominik
Published: April 2021

Obstructive sleep apnoea (OSA) is highly prevalent in atrial fibrillation (AF) patients and associated with reduced response to rhythm control strategies. However, there is no practical guidance on testing for OSA in AF patients and for OSA treatment implementation. We sought to evaluate current practices and identify challenges of OSA management in AF. A descriptive cross-sectional study was performed with a content-validated survey to evaluate OSA management in AF by healthcare practitioners. Survey review, editing, and dissemination occurred via the European Heart Rhythm Association and the Association of Cardiovascular Nursing and Allied Professions and direct contact with arrhythmia centres. In total, 186 responses were collected. OSA-related symptoms were ranked as the most important reason to test for OSA in AF patients. The majority (67.7%) indicated that cardiologists perform ‘ad-hoc’ referrals. Only 11.3% initiated systematic testing by home sleep test or respiratory polygraphy and in addition, 10.8% had a structured OSA assessment pathway in place at the cardiology department. Only 6.7% of the respondents indicated that they test >70% of their AF patients for OSA as a component of rhythm control therapy. Various barriers were reported: no established collaboration between cardiology and sleep clinic (35.6%); lack in skills and knowledge (23.6%); lack of financial (23.6%) and personnel-related resources (21.3%). Structured testing for OSA occurs in the minority of AF patients. Centres apply varying methods. There is an urgent need for increased awareness and standardized pathways to allow OSA testing and treatment integration in the management of AF.
Association between handgrip strength and mental health in Korean adolescents
Authors: Hwang In Cheol , Ahn Hong Yup , Choi Soo Jung
Published: April 2021

Background and Objectives

Muscle strength is associated with adverse mental health outcomes in adults; however, few studies have examined this association among adolescents. This study investigated the association between handgrip strength and mental health in a nationally representative sample of Korean adolescents.

Methods

We performed a cross-sectional study of 3530 adolescent (12–18 years old) from the 2014–2017 Korean National Health and Nutrition Survey. Handgrip strength was defined as the maximum measurement in kilograms from the dominant hand. Adverse mental health included the presence of perceived stress, depressive mood and suicidal ideation. Logistic regression models were used with adjustment for potential confounders.

Results

The mean age ± SD of the study participants was 14.9 ± 2.0 years. Girls (47.5% of participants) had poorer mental health than boys. For boys, each 1-kg increase in handgrip strength was associated with a 3% decrease in the odds of having perceived stress and depressive moods. For girls, there was a positive association between handgrip strength and perceived stress. The relationship between handgrip strength and perceived stress was dose dependent for both sexes.

Conclusions

Low handgrip strength was associated with poor mental health among boys. Future research is required to validate our findings and to establish whether interventions to increase muscular strength can reduce the prevalence of perceived stress and depressive mood in boys.
The Burden of Invasive Bacterial Disease and the Impact of 10-Valent Pneumococcal Conjugate Vaccine in Children <5 years hospitalized for Meningitis in Lusaka, Zambia, 2010–2019
Authors: Yamba Kaunda , Mpabalwani Evans , Nakazwe Ruth , Mulendele Evans , Weldegebriel Goitom , Mwenda Jason M , Katsande Reggis , de Gouveia Linda , Chizema-Kawesha Elizabeth , Chanda Raphael , Matapo Belem , Mwansa James C L , Lukwesa-Musyani Chileshe
Published: April 2021

Background

Despite the availability of vaccines, invasive bacterial diseases remain a public health concern and cause childhood morbidity and mortality. We investigated the characteristics of etiological agents causing bacterial meningitis in children <5 years in the years pre- (2010–2012) and post- (2014–2019) 10-valent pneumococcal conjugate vaccine (PCV10) introduction in Zambia.

Methods

Streptococcus pneumoniae (Spn), Haemophilus influenzae (Hi), and Neisseria meningitidis (Nm) from cerebrospinal fluid (CSF) were identified by microbiological culture and/or real-time polymerase chain reaction.

Results

During the surveillance period, a total of 3811 children were admitted with suspected meningitis, 16% (598 of 3811) of which were probable cases. Bacterial meningitis was confirmed in 37% (221 of 598) of the probable cases. Spn pneumoniae, Hi, and Nm accounted for 67% (148 of 221), 14% (31 of 221), and 19% (42 of 221) of confirmed cases, respectively. Thirty-six percent of pneumococcal meningitis was caused by 10-valent pneumococcal conjugate vaccine (PCV10) serotypes, 16% 13-valent pneumococcal conjugate vaccine and 39% by nonvaccine serotype (NVS). There was an association between the introduction of PCV10 vaccination and a decrease in both Spn meningitis and the proportion of PVC10 serotypes in the postvaccination period. Antimicrobial susceptibility of 47 Spn isolates revealed 34% (16 of 47) penicillin resistance. The 31 serotyped Hi accounted for 74% type b (Hib) and 10% type a (Hia). All 42 serogrouped Nm belonged to serogroup W.

Conclusions

There was a decline in pneumococcal meningitis and proportion of PCV10 serotypes in the postvaccination period. However, the serotype replacement with non-PCV10 serotypes and penicillin resistance warrant continued surveillance to inform policy.
Pretreatment with metformin protects mice from whole-body irradiation
Authors: Da Fei , Guo Juan , Yao Lin , Gao Qiaohui , Jiao Shengyuan , Miao Xia , Liu Junye
Published: April 2021

Metformin, a first-line oral drug for type II diabetes mellitus, not only reduces blood glucose levels, but also has many other biological effects. Recent studies have been conducted to determine the protective effect of metformin in irradiation injuries. However, the results are controversial and mainly focus on the time of metformin administration. In this study, we aimed to investigate the protective effect of metformin in BALB/c mice exposed to 6 Gy or 8 Gy of a 60Co source of γ-rays for total body irradiation (TBI). Survival outcomes were assessed following exposure to 8 Gy or 6 Gy TBI, and hematopoietic damage and intestinal injury were assessed after exposure to 6 Gy TBI. Metformin prolonged the survival of mice exposed to 8 Gy TBI and improved the survival rate of mice exposed to 6 Gy TBI only when administered before exposure to irradiation. Moreover, pretreatment with metformin reduced the frequency of micronuclei (MN) in the bone marrow of mice exposed to 6 Gy TBI. Pretreatment of metformin also protected the intestinal morphology of mice, reduced inflammatory response and decreased the number of apoptotic cells in intestine. In conclusion, we demonstrated that pretreatment with metformin could alleviate irradiation injury.
Paraneoplastic limbic encephalitis due to lung squamous cell carcinoma
Authors: So Tetsuya , Yamashita Naoki , Shimokawa Hidehiko , Yamaoka Masatoshi , Kawano Daigo , Yoshimatsu Takashi , Oyama Tsunehiro
Published: April 2021

Paraneoplastic limbic encephalitis (PLE) is one of paraneoplastic neurological syndrome (PNS). We herein report a case of PLE due to lung squamous cell carcinoma. A 80-year-old woman visited because of several neurological symptoms. Brain magnetic resonance imaging revealed hyperintense signals at the splenium of the corpus callosum, suggesting limbic encephalitis. Chest X-ray and computed tomography showed a 17 × 14 mm tumor in the left lung field, suggesting lung cancer. Surgical examination revealed T1bN0M0 lung squamous cell carcinoma. She died 50 days after surgery due to the rapid progression of encephalitis. PLE is an extremely rare disorder, and even a case in the early stage of cancer shows poor prognosis. We should doubt a possibility of PLE, and detailed brain examination should be performed in case of consciousness disorder with rapid progression in the cancer patient.
Effects of water temperature on glochidium viability of Unio crassus and Sinanodonta woodiana: implications for conservation, management and captive breeding
Authors: Benedict Alia , Geist Juergen
Published: April 2021

The global decline of freshwater bivalves (Unionida) has prompted many programmes for their conservation and augmentation, which often include a captive breeding component. One key point to such programmes is the collection, maintenance and use of mussel glochidium larvae, which require attachment to a fish host in a sensitive parasitic stage of their life cycle. Understanding the thermal limits of glochidia can increase knowledge of mussel larval survival and ultimately aid in the development of conservation programmes. Glochidia of the endangered thick-shelled river mussel Unio crassus and the non-native Chinese pond mussel Sinanodonta woodiana were observed for active clamping ability at 5, 15, 17, 20 and 25 °C over the course of a 7-d period. The results from this study confirm that an inverse relationship between water temperature and larval viability can be observed in both species. Additionally, the significantly higher thermal tolerance of S. woodiana indicates that the species exhibits competitive invasive behaviour beginning from the larval stage. These findings also suggest that the collection and transportation of glochidia from genetically important yet distant populations is feasible if the larvae can be maintained at temperatures between 5 and 15 °C.
Measuring nonhomologous end-joining, homologous recombination and alternative end-joining simultaneously at an endogenous locus in any transfectable human cell
Authors: Hussain Suleman S , Majumdar Rahul , Moore Grace M , Narang Himanshi , Buechelmaier Erika S , Bazil Maximilian J , Ravindran Pavithran T , Leeman Jonathan E , Li Yi , Jalan Manisha , Anderson Kyrie S , Farina Andrea , Soni Rekha , Mohibullah Neeman , Hamzic Edin , Rong-Mullins Xiaoqing , Sifuentes Christopher , Damerla Rama R , Viale Agnes , Powell Simon N , Higginson Daniel S
Published: April 2021

Double strand break (DSB) repair primarily occurs through 3 pathways: non-homologous end-joining (NHEJ), alternative end-joining (Alt-EJ), and homologous recombination (HR). Typical methods to measure pathway usage include integrated cassette reporter assays or visualization of DNA damage induced nuclear foci. It is now well understood that repair of Cas9-induced breaks also involves NHEJ, Alt-EJ, and HR pathways, providing a new format to measure pathway usage. Here, we have developed a simple Cas9-based system with validated repair outcomes that accurately represent each pathway and then converted it to a droplet digital PCR (ddPCR) readout, thus obviating the need for Next Generation Sequencing and bioinformatic analysis with the goal to make Cas9-based system accessible to more laboratories. The assay system has reproduced several important insights. First, absence of the key Alt-EJ factor Pol θ only abrogates ∼50% of total Alt-EJ. Second, single-strand templated repair (SSTR) requires BRCA1 and MRE11 activity, but not BRCA2, establishing that SSTR commonly used in genome editing is not conventional HR. Third, BRCA1 promotes Alt-EJ usage at two-ended DSBs in contrast to BRCA2. This assay can be used in any system, which permits Cas9 delivery and, importantly, allows rapid genotype-to-phenotype correlation in isogenic cell line pairs.
Exenatide Adjunct to Nicotine Patch Facilitates Smoking Cessation and May Reduce Post-Cessation Weight Gain: A Pilot Randomized Controlled Trial
Authors: Yammine Luba , Green Charles E , Kosten Thomas R , de Dios Constanza , Suchting Robert , Lane Scott D , Verrico Christopher D , Schmitz Joy M
Published: April 2021

Introduction

Approved pharmacological treatments for smoking cessation are modestly effective, underscoring the need for improved pharmacotherapies. Glucagon-like peptide-1 receptor (GLP-1R) agonists attenuate the rewarding effects of nicotine in preclinical studies. We examined the efficacy of extended-release exenatide, a GLP-1R agonist, combined with nicotine replacement therapy (NRT, patch) for smoking cessation, craving, and withdrawal symptoms, with post-cessation body weight as a secondary outcome.

Methods

Eighty-four prediabetic and/or overweight smokers were randomized (1 : 1) to once-weekly placebo or exenatide, 2 mg, subcutaneously. All participants received NRT (21 mg) and brief smoking cessation counseling. Seven-day point prevalence abstinence (expired CO level ≤5 ppm), craving, withdrawal, and post-cessation body weight were assessed following 6 weeks of treatment. A Bayesian approach for analyzing generalized linear models yielded posterior probabilities (PP) to quantify the evidence favoring hypothesized effects of treatment on the study outcomes.

Results

Exenatide increased the risk for smoking abstinence compared to placebo (46.3% and 26.8%, respectively), (risk ratio [RR] = 1.70; 95% credible interval = [0.96, 3.27]; PP = 96.5%). Exenatide reduced end-of-treatment craving in the overall sample and withdrawal among abstainers. Post-cessation body weight was 5.6 pounds lower in the exenatide group compared to placebo (PP = 97.4%). Adverse events were reported in 9.5% and 2.3% of participants in the exenatide and placebo groups, respectively.

Conclusions

Exenatide, in combination with the NRT improved smoking abstinence, reduced craving and withdrawal symptoms, and decreased weight gain among abstainers. Findings suggest that the GLP-1R agonist strategy is worthy of further research in larger, longer duration studies.

Implications

Despite considerable progress in tobacco control, cigarette smoking remains the leading cause of preventable disease, disability, and death. In this pilot study, we showed that extended-release exenatide, a glucagon-like peptide-1 receptor agonist, added to the nicotine patch, improved abstinence and mitigated post-cessation body weight gain compared to patch alone. Further research is needed to confirm these initial positive results.