bluuebunny/crossref_metadata_2025 huggingface dataset:
Psychometric properties of infant electroencephalography: Developmental stability, reliability, and construct validity of frontal alpha asymmetry and delta–beta coupling
Authors: Anaya Berenice , Ostlund Brendan , LoBue Vanessa , Buss Kristin , Pérez‐Edgar Koraly
Published: August 2021

Resting‐state electroencephalography (EEG) provides developmental neuroscientists a noninvasive view into the neural underpinnings of cognition and emotion. Recently, the psychometric properties of two widely used neural measures in early childhood—frontal alpha asymmetry and delta–beta coupling—have come under scrutiny. Despite their growing use, additional work examining how the psychometric properties of these neural signatures may change across infancy is needed. The current study examined the developmental stability, split‐half reliability, and construct validity of infant frontal alpha asymmetry and delta–beta coupling. Infants provided resting‐state EEG data at 8, 12, and 18 months of age (N = 213). Frontal alpha asymmetry and delta–beta coupling showed significant developmental change from 8 to 18 months. Reliability for alpha asymmetry, and alpha, delta, and beta power, individually, was generally good. In contrast, the reliability of delta–beta coupling scores was poor. Associations between frontal alpha asymmetry and approach tendencies generally emerged, whereas stronger (over‐coupled) delta–beta coupling scores were associated with profiles of dysregulation and low inhibition. However, the individual associations varied across time and specific measures of interest. We discuss these findings with a developmental lens, highlighting the importance of repeated measures to better understand links between neural signatures and typical and atypical development.
Sociodemographics and chronic stress in mother–toddler dyads living in poverty
Authors: Bates Randi A. , Ford Jodi L. , Jiang Hui , Pickler Rita , Justice Laura M. , Dynia Jaclyn M. , Ssekayombya Prosper
Published: August 2021

Experiencing chronic stress early in life is associated with later health disparities, and poverty may be a significant stressor for both mothers and children. With a sample of primarily Black and White mothers (N = 75) and toddlers (N = 71) living in poverty in the United States, we examined the direct relations between sociodemographic conditions of poverty and chronic physiological stress. Mothers completed questionnaires on sociodemographics, including mother/toddler race, mother's education, father's education, poverty level, economic hardship, marital status, unemployment status, and toddler sex. Physiological chronic stress was measured by assaying the cortisol content of 4 cm samples of hair cut from the posterior vertex of mothers and toddlers (20–24 months of age) to represent 4 months of stress. Mothers’ and toddlers’ chronic stress was significantly, moderately, and positively associated. Toddlers had a trending relationship of moderately higher chronic stress if they were Black compared to not Black. Mothers had significantly, moderately higher chronic stress if they were Black or had a Black toddler (compared to not Black), not married (compared to married), or were working (compared to not working). The findings suggest that these mothers, simultaneously navigating poverty and parenting a toddler, need resources to reduce chronic stress.
Longitudinal investigation of shyness and physiological vulnerability: Moderating influences of attention biases to threat and safety
Authors: Hassan Raha , Schmidt Louis A.
Published: August 2021

Shyness has long been identified as a vulnerability factor to developing psychosocial problems, but there is heterogeneity in these observed outcomes. One potential factor underlying these relations is individual differences in threat sensitivity. Using a longitudinal design, we examined whether attentional biases toward social threat and safety measured during adulthood moderated the association between shyness measured in emerging adulthood (N = 83, nfemale = 48; Mage = 23.56 years, SDage = 1.09 years) and frontal electroencephalogram (EEG) asymmetry at rest, a physiological index of vulnerability to psychopathology, measured nearly a decade later in adulthood (Mage = 31.68 years, SDage = 2.27 years). We found that only biases to threat moderated the association between shyness and resting frontal EEG asymmetry longitudinally. In individuals who displayed relative vigilance to social threat, shyness was associated with greater relative right frontal EEG activity at rest (i.e., increased physiological vulnerability). These findings suggest that attentional biases to threat may play a role in understanding the relation between shyness and some known physiological vulnerabilities to psychopathology in adults.
Stereospecific Synthesis of Conjugated Dienes by Carbenoid Eliminative Cross‐Coupling Using Lithiated Allylic Carbamates
Authors: Tanpure Subhash D. , Blakemore Paul R.
Published: August 2021

1,2,4‐Trisubstituted 1,3‐butadienes were prepared in a stereocontrolled manner by carbenoid eliminative cross‐coupling between stereodefined lithiated secondary allylic carbamates and α‐carbamoyloxyalkyl boronates. All four geometric isomers of 4,7‐dimethyl‐1‐phenylocta‐3,5‐diene were stereospecifically generated [yields 44–73 %, dr (Δ3,4)=84 : 16 to 97 : 3] by appropriate combinations of (S,E)‐ or (S,Z)‐i‐PrCH=CHCLi(Me)OCb with (R)‐Ph(CH2)2CH(Bneo)OCb. A conjugated cyclohexenylidene and a model diene representing the C5‐C12 domain of cytotoxin callystatin A, were similarly elaborated in a stereochemically programmed manner. The configuration of the 1,2‐disubstituted alkene within the Li‐carbenoid was preserved in the diene product and the newly generated trisubstituted alkene component of the diene could be selectively installed in either (E)‐ or (Z)‐configuration by variation in carbenoid stereochemical pairing (like or unlike) and/or the mode of the elimination stage (syn or anti).
A novel structure preserving semi‐implicit finite volume method for viscous and resistive magnetohydrodynamics
Authors: Fambri Francesco
Published: August 2021

In this work we introduce a novel semi‐implicit structure‐preserving finite‐volume/finite‐difference scheme for the viscous and resistive equations of magneto‐hydrodynamics (VRMHD) based on an appropriate 3‐split of the governing PDE system, which is decomposed into a first convective subsystem, a second subsystem involving the coupling of the velocity field with the magnetic field, and a third subsystem involving the pressure‐velocity coupling. The nonlinear convective terms are discretized explicitly, while the remaining two subsystems accounting for the Alfvén waves and the magneto‐acoustic waves are treated implicitly. Thanks to this, the final algorithm is at least formally constrained only by a mild CFL stability condition depending on the velocity field of the pure hydrodynamic convection. To preserve the divergence‐free constraint of the magnetic field exactly at the discrete level, a proper set of overlapping dual (staggered) meshes is employed. The resulting linear algebraic systems are shown to be symmetric and therefore can be solved by means of an efficient standard matrix‐free conjugate gradient algorithm. The final scheme can be regarded as a novel shock‐capturing, conservative, and structure preserving semi‐implicit scheme for VRMHD. Several numerical tests are presented to show the main features of our novel divergence‐free semi‐implicit FV/FD solver: linear‐stability in the sense of Lyapunov is verified at a prescribed constant equilibrium solution; a second‐order of convergence is obtained for a smooth time‐dependent solution; shock‐capturing capabilities are proven against a standard set of stringent MHD shock‐problems; accuracy and robustness are verified against a non‐trivial set of two‐ and three‐dimensional MHD problems.
Covariate adjusted inference of parent‐of‐origin effects using case–control mother–child paired multilocus genotype data
Authors: Zhang Kai , Zhang Hong , Hochner Hagit , Chen Jinbo
Published: August 2021

It is of great interest to identify parent‐of‐origin effects (POEs) since POEs play an important role in many human heritable disorders and human early life growth and development. POE is sometimes referred to as imprinting effect in the literature. Compared with the standard logistic regression analyses, retrospective likelihood‐based statistical methods are more powerful in identifying POEs when data are collected from related individuals retrospectively. However, none of existing retrospective‐based methods can appropriately incorporate covariates that should be adjusted for if they are confounding factors. In this paper, a novel semiparametric statistical method, M‐HAP, is developed to detect POEs by fully exploring available information from multilocus genotypes of case–control mother–child pairs and covariates. Some large sample properties are established for M‐HAP. Finite sample properties of M‐HAP are illustrated by extensive simulation studies and real data applications to the Jerusalem Perinatal Study and the Danish National Birth Cohort study, which confirm the desired superiority of M‐HAP over some existing methods. M‐HAP has been implemented in the updated R package CCMO.
Role of primary tumor resection in patients with metastatic medullary thyroid cancer who have unresectable distant metastases
Authors: Zhuang Shi‐Min , Xie Liang‐En , Pang Feng , Zhong Qian‐Yi , Sun Xiao‐Mei , Wen Wei‐Ping , Liu Tian‐Run
Published: August 2021

Background

Whether patients with medullary thyroid carcinoma (MTC) who have unresectable synchronous distant metastases should undergo primary surgical resection (PTR) remains controversial. This study aimed to identify predictive factors associated with the survival of such patients.

Methods

We conducted a retrospective study of patients with MTC who were registered in the Surveillance, Epidemiology, and End Results registry. The overall and cancer‐specific mortality rates were assessed using risk‐adjusted Cox proportional hazards regression modeling and stratified propensity score matching.

Results

One hundred and eight matched patients were assessed. Patients in the PTR group had lower overall mortality than did those in the non‐PTR group. The 1‐, 3‐, and 5‐year overall and cancer‐specific survival rates in the PTR group were significantly higher.

Conclusions

PTR appears to be the most appropriate intervention for patients with good performance status. Such patients are likely to benefit from surgery and to experience long‐term stable disease.
RGD‐pectin microfiber patches for guiding muscle tissue regeneration
Authors: Campiglio Chiara Emma , Carcano Anna , Draghi Lorenza
Published: August 2021

Opportunely arranged microscaled fibers offer an attractive 3D architecture for tissue regeneration as they may enhance and stimulate specific tissue regrowth. Among different scaffolding options, encapsulating cells in degradable hydrogel microfibers appears as particularly attractive strategy. Hydrogel patches, in fact, offer a highly hydrated environment, allow easy incorporation of biologically active molecules, and can easily adapt to implantation site. In addition, microfiber architecture is intrinsically porous and can improve mass transport, vascularization, and cell survival after grafting. Anionic polysaccharides, as pectin or the more popular alginate, represent a particularly promising choice for the fabrication of cell‐laden patches, due to their extremely mild gelation in the presence of divalent ions and widely accepted biocompatibility. In this study, to combine the favorable properties of hydrogel and fibrous architecture, a simple coaxial flow wet‐spinning system was used to prepare cell‐laden, 3D fibrous patches using RGD‐modified pectin. Rapid fabrication of coherent self‐standing patches, with diameter in the range of 100–200 μm and high cell density, was possible by accurate choice of pectin and calcium ions concentrations. Cells were homogeneously dispersed throughout the microfibers and remained highly viable for up to 2 weeks, when the initial stage of myotubes formation was observed. Modified‐pectin microfibers appear as promising scaffold to support muscle tissue regeneration, due to their inherent porosity, the favorable cell–material interaction, and the possibility to guide cell alignment toward a functional tissue.
Ginsenoside Rg3 attenuates cisplatin‐induced kidney injury through inhibition of apoptosis and autophagy‐inhibited NLRP3
Authors: Zhai Jinghui , Gao Huan , Wang Shuo , Zhang Sixi , Qu Xiaoyu , Zhang Yueming , Tao Lina , Sun Jingmeng , Song Yanqing , Fu Li
Published: August 2021

The NOD‐like receptor family pyrin domain‐containing (NLRP3) inflammasomes is centrally implicated in cisplatin (CP)‐induced kidney injury. Autophagy is critical for inhibiting production of NLRP3 protein that effectively reduces the inflammatory response. Ginsenoside Rg3 (SY), an active component extracted from ginseng, is reported to protect against CP‐induced nephrotoxicity. However, the mechanisms underlying renoprotection by SY have not been established to date. Our results indicate that SY attenuated CP‐induced apoptosis and damage in vivo and in vitro, as evidenced by increased cell viability, decreased the proportion of late apoptotic cells, elevated mitochondrial membrane potential, and ameliorated histopathological damage of the kidney. SY ameliorated CP‐induced human renal tubular (HK‐2) cells and kidney injury through upregulation of LC3II/I and beclin‐1, inhibition of p62, NLRP3, ASC, caspase‐1, and interleukin‐1β. However, blockade of autophagy by 3‐methyladenine reversed the suppression of SY on NLRP3 inflammasome activation and the protection of SY on HK‐2 cells. Our collective results support the utility of SY as a therapeutic agent that effectively protects against CP‐induced kidney injury by activating the autophagy‐mediated NLRP3 inhibition pathway.
The influence of aeration control and temperature reduction on nitrogen removal and microbial community in two anammox‐based hybrid sequencing batch biofilm reactors
Authors: Azari Mohammad , Jurnalis Aisha , Denecke Martin
Published: August 2021

BACKGROUND

Two hybrid biofilm reactors, an integrated fixed‐film activated sludge–sequencing batch reactor (IFAS‐SBR) and a hybrid SBR with a mixture of activated sludge and granules, were used to reach enhanced nitrogen removal based on the anaerobic ammonium oxidation (anammox) process under intermittent aeration.

RESULTS

IFAS‐SBR reached a more stable performance after a rapid start‐up period of 25 days, and it showed a more reliable performance than the other reactor. The highest nitrogen removal efficiency (NRE) was up to 99% based on NH4+‐N concentration and 91% based on total nitrogen concentration (TIN). A nitrogen removal rate of 0.01 to 0.15 kgN m−3 d−1 was achieved throughout the operation based on the TIN. The set‐point of maximum dissolved oxygen (DO) at the peak of each aeration cycle was maintained at 1.2 ± 0.1 mg L−1. The optimum working range for daily average DO concentration was 0.2–0.7 mg L−1. Cold temperatures caused a decline of NRE, but NRE > 50% for temperatures above 13 °C was achieved.

CONCLUSIONS

Results implied a higher abundance of Candidatus brocadia species of anammox bacteria in the biofilm samples and Denitratisoma genus in the flocs. The most substantial contribution of shared taxa among all samples at class level was Betaproteobacteria and Gammaproteobacteria, and the least abundant class was Nitrospira. Overall, results implied that IFAS‐SBR is a robust configuration for anammox‐based nitrogen removal in sidestream, and controlled intermittent aeration could suppress nitrite oxidation and help to regain system efficiency.
A case of human immunodeficiency virus (HIV) infection without increase in HIV RNA level: A rare observation during the modern antiretroviral therapy era
Authors: Iwata Kentaro , Morishita Naomi , Otani Sachiyo
Published: August 2021

It is known that some with human immunodeficiency virus (HIV)–positive patients can remain immunocompetent for long period, maintaining their CD4‐positive T lymphocytes (CD4 cells) while suppressing HIV. However, this population became rarely seen recently since potent antiretroviral therapy (ART) became available worldwide, and the latest guidelines recommend initiating ART regardless of the status of immunity of the patients. Herein, we present a rather unusual case of HIV‐1 infection, where the patient was hospitalized for 3 years and was accidentally found to have the infection, without increasing his HIV RNA level in serum although his CD4 cells were decreased.
Mechano‐energetic aspects of Barth syndrome
Authors: Dudek Jan , Maack Christoph
Published: August 2021

Energy‐demanding organs like the heart are strongly dependent on oxidative phosphorylation in mitochondria. Oxidative phosphorylation is governed by the respiratory chain located in the inner mitochondrial membrane. The inner mitochondrial membrane is the only cellular membrane with significant amounts of the phospholipid cardiolipin, and cardiolipin was found to directly interact with a number of essential protein complexes, including respiratory chain complexes I to V. An inherited defect in the biogenesis of cardiolipin causes Barth syndrome, which is associated with cardiomyopathy, skeletal myopathy, neutropenia and growth retardation. Energy conversion is dependent on reducing equivalents, which are replenished by oxidative metabolism in the Krebs cycle. Cardiolipin deficiency in Barth syndrome also affects Krebs cycle activity, metabolite transport and mitochondrial morphology. During excitation‐contraction coupling, calcium (Ca2+) released from the sarcoplasmic reticulum drives sarcomeric contraction. At the same time, Ca2+ influx into mitochondria drives the activation of Krebs cycle dehydrogenases and the regeneration of reducing equivalents. Reducing equivalents are essential not only for energy conversion, but also for maintaining a redox buffer, which is required to detoxify reactive oxygen species (ROS). Defects in CL may also affect Ca2+ uptake into mitochondria and thereby hamper energy supply and demand matching, but also detoxification of ROS. Here, we review the impact of cardiolipin deficiency on mitochondrial function in Barth syndrome and discuss potential therapeutic strategies.
Sinomenine increases adenosine A2A receptor and inhibits NF-κB to inhibit arthritis in adjuvant-induced-arthritis rats and fibroblast-like synoviocytes through α7nAChR
Authors: Yi Lang , Ke Junyu , Liu Jiayan , Lai Huili , Lv Yanjun , Peng Chong , Zhi Yingkun , Du Qun , Liu Liang , Wang Peixun , Zhou Hua , Dong Yan
Published: August 2021

Sinomenine (SIN) is a clinical drug for treating rheumatoid arthritis (RA) in China. Our previous study found SIN inhibited inflammation via alpha7 nicotinic acetylcholine receptor (α7nAChR) in macrophages in vitro. Adenosine receptor A2A has anti-inflammatory and immunosuppressive function. However, the mechanisms of SIN acting on α7nAChR and the effect on adenosine A2A receptor (A2AR) in RA are not clear. In the present study, the effects of SIN on adjuvant-induced-arthritis (AIA) rats in vivo and on fibroblast-like synoviocytes (FLSs) in vitro were investigated. Indomethacin (Indo) and methotrexate (MTX), the clinical anti-arthritis drugs, were used as controls. Nicotine (Nic), a specific agonist of α7nAChR, was used as a control for targeting α7nAChR. Alpha-bungarotoxin (α-BTX), the antagonist of α7nAChR or small interference RNA (siRNA) was used to block or knock down α7nAChR. Results showed that SIN decreased arthritis index, hind paw volume, erythrocyte sedimentation (ESR) and serum TNF-α in AIA rats, and α-BTX attenuated the earlier-mentioned effects of SIN and Nic, but not Indo and MTX. The expressions of A2AR in synovium declined in AIA rats, but remarkably increased after the intervention of SIN. The expression of A2AR decreased by LPS or TNF-α, but increased by SIN; cAMP also increased by SIN in FLSs in vitro. SIN inhibited the expression of MCP-1, IL-6, and vascular endothelial growth factor in LPS-induced FLSs. SIN inhibited the activation of NF-κB. Meanwhile, α-BTX or α7nAChR siRNA blocked the earlier-mentioned effects of SIN in FLSs. Results suggested the expressions of A2AR in synovium and FLSs are negatively correlated with the arthritis progression of AIA rats and the activation of FLSs. SIN increases A2AR and inhibits the activation of NF-κB pathway via α7nAChR in AIA rats and FLSs.
Utility of Advanced DWI in the Detection of Spinal Cord Microstructural Alterations and Assessment of Neurologic Function in Cervical Spondylotic Myelopathy Patients
Authors: Zhang Meng‐Ze , Ou‐Yang Han‐Qiang , Liu Jian‐Fang , Jin Dan , Wang Chun‐Jie , Zhang Xian‐Chang , Zhao Qiang , Liu Xiao‐Guang , Liu Zhong‐Jun , Lang Ning , Jiang Liang , Yuan Hui‐Shu
Published: August 2021

Background

Diffusion‐weighted imaging (DWI) can quantify the microstructural changes in the spinal cord. It might be a substitute for T2 increased signal intensity (ISI) for cervical spondylotic myelopathy (CSM) evaluation and prognosis.

Purpose

The purpose of the study is to investigate the relationship between DWI metrics and neurologic function of patients with CSM.

Study Type

Retrospective.

Population

Forty‐eight patients with CSM (18.8% females) and 36 healthy controls (HCs, 25.0% females).

Field Strength/Sequence

3 T; spin‐echo echo‐planar imaging‐DWI; turbo spin‐echo T1/T2; multi‐echo gradient echo T2*.

Assessment

For patients, conventional MRI indicators (presence and grades of T2 ISI), DWI indicators (neurite orientation dispersion and density imaging [NODDI]‐derived isotropic volume fraction [ISOVF], intracellular volume fraction, and orientation dispersion index [ODI], diffusion tensor imaging [DTI]‐derived fractional anisotropy [FA] and mean diffusivity [MD], and diffusion kurtosis imaging [DKI]‐derived FA, MD, and mean kurtosis), clinical conditions, and modified Japanese Orthopaedic Association (mJOA) were recorded before the surgery. Neurologic function improvement was measured by the 3‐month follow‐up recovery rate (RR). For HCs, DWI, and mJOA were measured as baseline comparison.

Statistical Tests

Continuous (categorical) variables were compared between patients and HCs using Student's t‐tests or Mann–Whitney U tests (chi‐square or Fisher exact tests). The relationships between DWI metrics/conventional MRI findings, and the pre‐operative mJOA/RR were assessed using correlation and multivariate analysis. P < 0.05 was considered statistically significant.

Results

Among patients, grades of T2 ISI were not correlated with pre‐surgical mJOA/RR (P = 0.717  and 0.175, respectively). NODDI ODI correlated with pre‐operative mJOA (r = −0.31). DTI FA, DKI FA, and NODDI ISOVF were correlated with the recovery rate (r = 0.31, 0.41, and −0.34, respectively). In multivariate analysis, NODDI ODI (DTI FA, DKI FA, NODDI ISOVF) significantly contributed to the pre‐operative mJOA (RR) after adjusting for age.

Data Conclusion

DTI FA, DKI FA, and NODDI ISOVF are predictors for prognosis in patients with CSM. NODDI ODI can be used to evaluate CSM severity.

Level of Evidence

3

Technical Efficacy Stage

5
Failure to thrive: A severe manifestation of interleukin 10 receptor A mutation in adult inflammatory bowel disease
Authors: Ruiz Nicole C. , Kamel Amir Y. , Liu Xiuli , Pham Angela , Forsmark Christopher , Glover Sarah
Published: August 2021

Background

Very early‐onset inflammatory bowel disease (VEO‐IBD) secondary to interleukin 10 receptor A (IL‐10RA) mutations has aggressive disease courses with increased nutrition needs compared with those in other monogenic forms of IBD.

Presentation

A male patient was hospitalized when he was 18 days old for bloody diarrhea, which was diagnosed as Crohn's disease at 6 months old. He showed failure to thrive (FTT) and worsening inflammation while receiving enteral nutrition (EN) and standard IBD treatment. He was hospitalized in 2016, at 28 years old, for a Crohn's flare when sequencing confirmed a heterozygous mutation in IL10‐RA. His weight and plasma micronutrient levels improved when he transitioned to parenteral nutrition (PN). He was initiated on anakinra while awaiting hematopoietic stem cell transplant, with substantial decrease in inflammation. He was able to gain weight, initiate an oral diet, and decrease his PN requirement.

Conclusion

Our patient experienced progressive FTT while receiving EN. VEO‐IBD incidence is rising, and its diagnosis is often delayed. Therefore, prompt recognition with treatment initiation is essential to improving nutrition outcomes in this patient population. Further investigation is warranted to determine whether these patients would benefit from early initiation of PN.
Analysis of Epoxy Nanocomposites Characteristics by Impedance Spectroscopy
Authors: Rashmi  , Sailaja R. R. N. , Madhu B. M.
Published: August 2021

The research work is carried out to analyse the electrical characteristics of glass fiber reinforced epoxy composites with the addition of multiwall carbon nanotubes and graphene nanoplatelets. The dispersion of 2wt.% multi walled carbon nanotubes(MWCNT) and 1‐3wt.% graphene nanoplatelets (GNP) into the epoxy resin is assisted with high shear mechanical mixing followed by ultrasonication. The epoxy‐filler mixture is transferred into temperature‐controlled resin bath for pultrusion process. The pultrusion process helps to resolve major issues like poor dispersion and agglomeration of nanofillers in epoxy resin. The XRD and SEM analysis indicates that fillers are dispersed homogeneously in the epoxy matrix. The electrical conductivity (σ) and impedance (Z) are studied in the frequency range (10 Hz‐8 MHz) with the variation in temperature (over 25 °C‐150 °C). It is observed that the addition of two conductive nanofillers results in a synergistic effect at the percolation threshold, and the conductivity value increases by few orders due to the formation of a number of conductive paths in the composite. The complex impedance decreases with increase in frequency for the composites except for the sample with 3wt.% GNP and 2wt.% MWCNT indicating the semiconducting behaviour. The complex impedance plot is characterized by the appearance of a single semi‐circular arc whose radii of curvature decreases with an increase in temperature, indicating the existence of electrical relaxation phenomena.
Effect of Hybrid Fillers on GFRP Epoxy Composites with Water Immersion and Thermal Conditioning
Authors: Balasubramanya Rashmi , Bhattacharya R. R. N. Sailaja , B. M. Madhu
Published: August 2021

Glass fiber reinforced epoxy composite with graphene nanoplatelets, multi‐walled carbon nanotubes, and aluminium trihydrate fillers are fabricated by the pultrusion method. The role of fillers in complementing each other, improving the dielectric properties of the epoxy matrix is not fully understood. The objective of this work is to investigate the effects of nano and micro fillers combination by short‐duration laboratory ageing techniques. A comparison of aged and unaged specimen is carried‐out by impedance spectroscopy and gravimetric analyses. The dielectric properties are observed to be dependent on the interaction between the fillers and the epoxy matrix, also on the relative permittivity of individual nanofillers, dissolved ions that diffuse with water into the bulk of the composites. The composite specimens are immersed in distilled water up to 360 h for water ageing and the temperature is varied from 25 °C to 200 °C for thermal ageing. The impedance spectroscopy of the composites is measured over the frequency range (10 Hz–8 MHz). The observed reduction in the impedance values indicate that dipolar polarization is occurring due to absorbed water molecules during water immersion and mobilization of free electrons is taking place due to an increase in temperature. This study indicates that the effect of ageing can be quantified in terms of changes in the impedance spectra. From the results obtained, the effect of fillers is implicit since diffusion coefficient values are reduced from 5.58 × 10−9 m2 s−1 of the base epoxy composite to 3.48 × 10−9 m2 s−1 in hybrid nanocomposites. The percentage of water absorption at equilibrium condition is reduced from 0.68% to 0.46% of the total mass.
Novel Core‐Shell System Based on Gelatin and Hydrophilic Polymers Useful as Concrete Self‐healing Systems
Authors: da Costa Vítor Corrêa , de Souza Fernando Gomes , Sousa Luana de Castro , Filho Romildo Dias Tolêdo
Published: August 2021

Concrete structures repair results in substantial economic and environmental issues. So, new technologies able to increase concrete lifetime are being developed. Among them, the self‐healing mechanisms, which can be improved by using polymers. Thus, three different materials are synthesized to act as self‐healing systems. They are: (I) cross‐linked gelatin mixed with CaCO3 (the self‐healing agent); (II) a core‐shell system based on the material I layered by poly(hydroxypropyl methacrylate); and (III) a second core‐shell structure based on the material I covered with poly(vinyl alcohol). Cross‐linking and grafting are performed using glutaraldehyde. Fourier‐transform infrared spectroscopy (FTIR) proves the structure obtaining. Thermogravimetric analysis and differential scanning calorimetry prove that the materials show thermal properties that allow their use in concrete applications. Swelling degree shows that all materials swell when in contact with water. Granulometry shows the materials are mostly in the millimeter scale. Last, an aqueous media release test shows that the three tested systems did not liberate significant amounts of CaCO3. Therefore, both the gelatin and gelatin + polymer systems can protect the healing material, avoiding the release of the self‐healing agent before the concrete cracking takes place.
Core‐Shell System Based on Gelatin and Poly(Vinyl Alcohol) (PVA) for Concrete Self‐Healing Applications: Synthesis, Characterization, and Optimization
Authors: da Costa Vítor Corrêa , Junior Fernando Gomes de Souza , Sousa Luana de Castro , Pal Kaushik , Filho Romildo Dias Tolêdo
Published: August 2021

Insofar the cost of repairing concrete structures reaches the trillions of dollars, new technologies, such as concrete self‐healing, are investigated continuously. Consequently, the main objective of this work is on the production of a cheap and easy‐to‐make material, which can be used in large‐scale applications, besides presenting similar results as other ones more complex systems. In brief, a core‐shell system is produced and investigated as a self‐healing agent. Aiming this, a mix of gelatin and sodium silicate (Na2SiO3) is used as the core, while poly(vinyl alcohol) (PVA) is the glutaraldehyde crosslinked shell. The obtained materials are characterized using several techniques, such as Fourier transform infrared spectroscopy (FTIR), as well as, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). FTIR proves the obtaining of the proposed system. In turn, TGA and DSC showed that the material could endure real‐life applications. Also, granulometry tests show that the obtained materials are mostly in the micrometric scale. The Na2SiO3 release is especially tested in aqueous media, proving the core‐shell system swells, releasing its active agent. Thereby, the obtained results allow concluding that the presented core‐shell material is useful to the self‐healing applications.
Acid Encapsulated Wax Particles Potentially Useful to Speed up Drilling in Carbonate Formations
Authors: Barros Alessandro , Pabis Maísa , Gomes Fernando , Pinto José Carlos , Nele Marcio
Published: August 2021

Encapsulated acids can increase the rate of penetration (ROP) during drilling operations by reacting with carbonate formations while avoiding corrosion of the metallic equipment parts. Drilling fluids can carry particles containing acid to the drilling tip where they will be mashed, and the acid released. The paraffin encapsulation is used in the processing of food ingredients, flavors, chemicals, drugs, protection of cosmetics, and in the oil industry. The novel solution presented in this paper is to use paraffin in the strong acid encapsulation to be added to the drilling fluid. Acid containing wax particles is prepared by the double emulsion technique. The results indicate that encapsulation efficiency is dependent on the wax to acid solution ratio and on acid concentration. Acid leakage is a significant concern; it is found to be directly dependent on acid concentration in the particle and on the particle wax fraction.
Development of Novel Dimpled Electrospun P(VDF‐TrFE) Nanofibers
Authors: K. Bicy , Kalarikkal Nandakumar , Rouxel Didier , Thomas Sabu
Published: August 2021

Electrospun polymeric nanofibrous membranes find application in various fields such as biomedical, energy, defense, etc. The flexibility of the electrospinning process and various parameters like temperature, solvent volatility, and polymer nature helps to design nanofibers with desired properties. The wide range application of nanofibers is because of its large surface to volume ratio. The surface area of a nanofiber can be further increased by fabricating dimpled or porous fibers. In the present work, dimpled electrospun polyvinylidene fluoride‐co‐trifluoroethylene (P(VDF‐TrFE)) nanofibers are prepared. The surface nanotopography of the fiber is studied using SEM and TEM analysis. The influence of rough surface on the wettability is evaluated by contact angle analysis. The result indicates that the nanofibrous membrane exhibits a very high contact angle (140°). In addition to this, mechanical property and thermal behavior of the membrane are also studied. The study reveals that the dimpled electrospun nanofibrous membrane is an excellent candidate in various applications where a large surface area is required.
Poly(Butylene Succinate) Molar Mass Calculation by GPC and 1H‐NMR
Authors: da Costa Vítor Corrêa , dos Santos Edson Rodrigo Fernandes , de Souza Jr Fernando Gomes
Published: August 2021

The determination of the molar mass of a polymer is a fundamental characterization. One of the most common techniques used for this purpose is gel permeation chromatography (GPC). However, the most used columns are not appropriate for low molar mass polymers, presenting results that are different from reality. For these cases, it is possible to use the nuclear magnetic resonance (NMR) technique to obtain molar mass values (based on calculations associated with spectra signals and the quantity of the polymer used in the analysis). However, in some cases, the resultant signals of different chain portions can be presented in the same spectral region, hampering calculations. Thus, this paper proposes the use of an external standard. This way, it can correlate to the molar mass of four different samples of poly(butylene succinate) (PBS) with different molar mass values. The results based on NMR spectra were different from those found using GPC, but both increased in the same proportion (R² = 0.8828). Since NMR presents an absolute result, it seems to be the most accurate result. This analysis method also allows us to quantify the experimental percentage of unsaturation, which was lower than the theoretical one due to losses during the PBS synthesis.
Graft Copolymerization of Acrylonitrile onto Sodium Salt of Partially Carboxymethylated Tamarind Kernel Powder Using Ceric Ammonium Nitrate as a Photo‐Initiator in an Aqueous Medium Under Ultraviolet‐Radiation
Authors: Trivedi Jignesh H. , Joshi Harshil A. , Trivedi Harikrishna C.
Published: August 2021

Ultraviolet (UV) radiation‐induced graft copolymerization of acrylonitrile (AN) onto sodium salt of partially carboxymethylated tamarind kernel powder (Na‐PCMTKP, ) has been carried out using ceric ammonium nitrate (CAN) as a photo‐initiator. The optimal UV‐radiation‐induced grafting conditions have been established with Na‐PCMTKP = 0.5 g (dry basis), [HNO3] = 0.2 mol L−1, [AN] = 0.295 mol L−1, [CAN] = 6.0 × 10−3 mol L−1, time = 6 h, temperature = 30 °C, volume of water = 144.58 mL, and total volume = 150 mL. The maximum percentage of grafting (%G) and percentage grafting efficiency (%GE) achieved under these established optimum reaction conditions are 361.16% and 89.33%, respectively. The various reaction conditions have been varied with a view to study their influence on the grafting yields (%G and %GE). A plausible mechanism to explain initiation, propagation, and termination of UV‐radiation‐initiated graft copolymerization has also been suggested. The influence of the efficiency of the photo‐initiator on the grafting yields has been investigated. Fourier transform infrared, thermogravimetric analysis, differential scanning calorimeter (DSC), and scanning electron microscopy techniques have been successfully used to provide the evidence of grafting of polyacrylonitrile onto Na‐PCMTKP. The kinetics of thermal decomposition of the graft copolymer, Na‐PCMTKP‐g‐PAN, has also been investigated with the help of the DSC curves obtained at different heating rates. The Ozawa and the Kissinger methods have been utilized for the evaluation of the kinetic parameters for the thermal decomposition of the graft copolymer sample. The synthesized graft copolymer after saponification may be used as a superabsorbent hydrogel for potential applications.
A Study on Annealing Process Influenced Electrical Properties of Ni/CeO2/p‐Si/Al Schottky Barrier Diodes
Authors: Nallabala Nanda Kumar Reddy , Kummara Venkata Krishnaiah , Chinnappa Yuvaraj , George P. P. , Manjunath V. , Sanniboina Jagadeesh , Reddy S. Manikanteswara , Gangasani Nethaji Reddy
Published: August 2021

The impact of annealing process on I‐V characteristics of Ni/CeO2/p‐Si/Al metal‐insulator‐semiconductor (MIS) type Schottky barrier diodes is investigated. The I‐V measurements are performed for the as‐deposited and 700 °C annealed samples at room temperature. The Schottky barrier height (SBH), ideality factor values are evaluated using thermionic emission theory and are found to be 0.67 eV, 1.21 for the as‐deposited sample and 0.72 eV, 1.01 for the 700 °C annealed sample. The calculations indicate that the 700 °C annealed sample for 45 min exhibits a lower series resistance (680 Ω) when compared to the as‐deposited sample (2206 Ω). The calculated shunt resistance for the 700 °C annealed sample is found to be 346 × 103 Ω which is found to be lower than that of the as‐deposited sample that is 962 × 103 Ω. In conclusion, it is elucidated that the intentionally deposited CeO2 (rare‐earth oxide) insulating layer at the interface of Ni/p‐Si and the subsequent annealing process significantly influence the electrical properties of the fabricated Ni/CeO2/p‐Si/Al MIS type Schottky barrier diodes.
Combinatorial technology revitalized by DNA‐encoding
Authors: Furka Árpád
Published: August 2021

Combinatorial chemistry invented nearly 40 years ago was welcomed with enthusiasm in the drug research community. The method offered access to a practically unlimited number of new compounds. The new compounds however are mixtures, and methods had to be developed for the identification of the bioactive components. This was one of the reasons why the method could not providethe expected cornucopia of new drugs. Among the different screening methods, two approaches seem to offer the best results. One of them is based on the intrinsic property of the combinatorial split and pool solid‐phase synthesis: One compound forms on each bead of the solid support. Different methods have been developed to encode the beads and identify the structure of compounds formed on them. The most important method applies DNA oligomers for encoding. As a second approach in screening, DNA‐encoded combinatorial libraries are synthesized omitting the solid support and the mixtures are screened in solution using affinity binding methods. Libraries containing billions and even trillions of components are synthesized and successfully tested, which led to the identification of a significant number of new leads.
“Spare Wheel” R&D in vertically related markets
Authors: Xue Mantian
Published: August 2021

In vertically related markets, downstream firms might launch Spare Wheel R&D plans to deal with potential embargoes enforced by countries where upstream monopolies are located. The existence of Spare Wheel R&D requires several conditions to be satisfied, including the equivalence of the upstream country's expected social welfare of different strategies, higher social welfare of the upstream country when choosing to export, moderate R&D efficiency, and relatively low R&D cost of the downstream firm. Besides, the most appropriate strategic R&D policy of the downstream country is to support the downstream firm's R&D project after the embargo is imposed.
Analytical and qualitative investigation of COVID‐19 mathematical model under fractional differential operator
Authors: Shah Kamal , Sher Muhammad , Rabai'ah Hussam , Ahmadian Ali , Salahshour Soheil , Pansera Bruno A.
Published: August 2021

In the current article, we aim to study in detail a novel coronavirus (2019‐nCoV or COVID‐19) mathematical model for different aspects under Caputo fractional derivative. First, from analysis point of view, existence is necessary to be investigated for any applied problem. Therefore, we used fixed point theorem's due to Banach's and Schaefer's to establish some sufficient results regarding existence and uniqueness of the solution to the proposed model. On the other hand, stability is important in respect of approximate solution, so we have developed condition sufficient for the stability of Ulam–Hyers and their different types for the considered system. In addition, the model has also been considered for semianalytical solution via Laplace Adomian decomposition method (LADM). On Matlab, by taking some real data about Pakistan, we graph the obtained results. In the last of the manuscript, a detail discussion and brief conclusion are provided.
Ultra‐wideband magnetoelectric antenna with dual polarization and compact size
Authors: Zheng Pei , Zhu Hailiang , Liu Ganyu , Qiu Yuwei , Wang Kai , Gao Lu , Liu Jiaqi
Published: August 2021

Design of ultra‐wideband (UWB) dual‐polarized magnetoelectric (ME) dipole antenna with compact size is presented. The proposed antenna consists of a double‐layer ME dipole, a pair of cross‐placed Γ‐shaped probes, and a box‐shaped reflector. Total size of the final design is 95 mm (0.87λ0) × 95 mm (0.87λ0) × 65 mm (0.6λ0). Both simulated and measured results show that the proposed antenna has an operating bandwidth of 127.3% (1–4.5 GHz) with voltage standing‐wave ratio (VSWR) ≤ 2.2 and 5.1 dBic ≤ gain ≤ 9.6 dBic. A stable unidirectional radiation pattern is achieved over the whole band. The cross‐polarization level is less than −15 dB and isolation between two ports exceeds 15 dB. Due to its compact size and good performance, the proposed antenna can be a competitive candidate in most wireless communication application scenarios.
In vitro and in vivo comparison of MRI chemical exchange saturation transfer (CEST) properties between native glucose and 3‐O‐Methyl‐D‐glucose in a murine tumor model
Authors: Anemone Annasofia , Capozza Martina , Arena Francesca , Zullino Sara , Bardini Paola , Terreno Enzo , Longo Dario Livio , Aime Silvio
Published: August 2021

D‐Glucose and 3‐O‐Methyl‐D‐glucose (3OMG) have been shown to provide contrast in magnetic resonance imaging‐chemical exchange saturation transfer (MRI‐CEST) images. However, a systematic comparison between these two molecules has yet to be performed. The current study deals with the assessment of the effect of pH, saturation power level (B1) and magnetic field strength (B0) on the MRI‐CEST contrast with the aim of comparing the in vivo CEST contrast detectability of these two agents in the glucoCEST procedure. Phosphate‐buffered solutions of D‐Glucose or 3OMG (20 mM) were prepared at different pH values and Z‐spectra were acquired at several B1 levels at 37°C. In vivo glucoCEST images were obtained at 3 and 7 T over a period of 30 min after injection of D‐Glucose or 3OMG (at doses of 1.5 or 3 g/kg) in a murine melanoma tumor model (n = 3–5 mice for each molecule, dose and B0 field). A markedly different pH dependence of CEST response was observed in vitro for D‐Glucose and 3OMG. The glucoCEST contrast enhancement in the tumor region following intravenous administration (at the 3 g/kg dose) was comparable for both molecules: 1%–2% at 3 T and 2%–3% at 7 T. The percentage change in saturation transfer that resulted was almost constant for 3OMG over the 30‐min period, whereas a significant increase was detected for D‐Glucose. Our results show similar CEST contrast efficiency but different temporal kinetics for the metabolizable and the nonmetabolizable glucose derivatives in a tumor murine model when administered at the same doses.
Structural relationships among adolescents’ peer attachment, career‐related self‐efficacy, parents’ attitudes and health risk behaviours
Authors: LEE Gyu Young , LEE Da Ye
Published: August 2021

Aim

This study aimed to determine whether the peer attachment of adolescents, mediated by career‐related self‐efficacy and having parents with positive attitudes, influences health risk behaviours.

Design

A cross‐sectional questionnaire survey.

Methods

This study adopted the secondary data analysis method, using the 2010 Korean Children and Youth Panel Survey (KCYPS). The 7th‐wave panel data of 1,932 first graders in high schools were analysed using structural equation modelling.

Results

The final model provided a good fit for the data. Having a close relationship with peers had a direct effect on adolescents’ health risk behaviours. High peer attachment also had an indirect effect on health risk behaviours, mediated by career‐related self‐efficacy and having parents with positive attitudes. Though adolescents with broad and intimate peer relationships may be exposed to more temptations towards health risk behaviours and tend to make riskier decisions, these influences are reduced by being exposed to positive parenting attitudes and having clear, conscious career goals.
Self‐assembled carbon nanofibers–silica nanocomposites for hydrogenated nitrile butadiene rubber reinforcement
Authors: Wang Fanghui , Dong Shengnan , Wang Zhongying , He Huan , Huang Xidai , Liu Dexin , Zhu Hong
Published: August 2021

In order to enhance the dispersion of silica (SiO2) in hydrogenated nitrile butadiene rubber (HNBR) and improve the mechanical properties of rubber composites, carbon nanofibers–silica (CNFs–SiO2) nanocomposites were prepared by the self‐assembly method and used as fillers in HNBR to obtain CNFs–SiO2/HNBR rubber composites. The composition, structures, and properties of CNFs–SiO2 nanocomposites and CNFs–SiO2/HNBR rubber composites were investigated. The results show that SiO2 loaded onto the surface of CNFs by electrostatic adsorption can significantly attenuate SiO2 nanoparticle agglomeration and improve the dispersion of nanocomposites in rubber. The maximum tensile strength (26.7 MPa), this peak strength was 1.6 times that of SiO2/HNBR and 3 times that of CNFs/HNBR, elongation at break (445%), and tear strength (43.7 kN/m) of CNFs–SiO2/HNBR were all reached at a CNF mass percentage of 4% and filling fraction of 50 phr. These results indicate that CNFs–SiO2 as a reinforcing filler can significantly improve rubber mechanical properties.