bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon mineralization, biological indicators, and phytotoxicity to assess the impact of urban sewage sludge on two light‐textured soils in a microcosm
Authors: Hechmi Sarra , Hamdi Helmi , Mokni‐Tlili Sonia , Zoghlami Inès Rahma , Khelil Mohamed Naceur , Benzarti Saoussen , Hassen Abdennaceur , Jedidi Naceur
Published: March 2020

The agricultural reuse of urban sewage sludge (USS) modifies soil properties depending on sludge quality, management, and pedo‐environmental conditions. The aim of this microcosm study was to assess C mineralization and subsequent changes in soil properties after USS addition to two typical Mediterranean soils: sandy (Soil S) and sandy loam (Soil A) at equivalent field rates of 40 t ha−1 (USS‐40) and 120 t ha−1 (USS‐120). Outcomes proved the biodegradability of USS through immediate CO2 release inside incubation bottles in a dose‐dependent manner. Accordingly, the highest rates of daily C emission were recorded with USS‐120 (3.7 and 3.9 mg kg−1 d−1 for Soils S and A, respectively) after 84 d of incubation at 25 °C. The addition of USS also improved soil fertility by enhancing soil macronutrients, microbial proliferation, and protease activity. Protease showed significant correlation with N, total organic C, and heterotrophic bacteria, reflecting the biostimulation and bioaugmentation effects of sludge. Soil indices like C/N/P stoichiometry and metabolic quotient (qCO2) varied mostly with mineralization rates of C and P in both soils. Despite a significant increase of soil salinity and total heavy metal content (lead, nickel, zinc, and copper) with USS dose, wheat germination was not affected by these changes. Both experimental soils showed intrinsic (Soil A) and incubation‐induced (Soil S) phytotoxicities that were alleviated by USS addition. This was likely due to the enhancement of biodegradation and/or retention of phytotoxicants originating from previous land uses. Urban sewage sludge amendments could have applications in soil remediation by reducing the negative effects of allelopathic and/or anthropogenic phytoinhibitors.
Prognostic impact of the number of metastatic lymph nodes in distal bile duct cancer: An analysis of Japanese registration cases by the study group for biliary surgery of the Japanese Society of Hepato‐Biliary‐Pancreatic Surgery
Authors: Ishihara Shin , Horiguchi Akihiko , Endo Itaru , Wakaki Toshifumi , Hirano Satoshi , Yamaue Hiroki , Yamamoto Masakazu
Published: March 2020

Background

Lymph node metastasis is an important prognostic factor for distal bile duct cancer. The number of lymph node metastases was adopted for nodal classification. However, different cutoff values have been proposed, ranging from two to five.

Methods

A total of 1748 cases who underwent curative surgery with pancreatoduodenectomy for distal bile duct cancer registered in the nationwide biliary tract cancer registry in Japan from 2008 to 2013 were included. Univariate Cox regression was performed to assess the effect of prognostic lymph node metastasis counts on mortality and to determine cutoff values.

Results

The overall survival rate after resection was 47.4% at 5 years. Univariate and multivariate analysis found prognostic factors to include lymph node metastasis. The cutoff point was set to two lymph node metastases using the Cox model. There were significant differences in pairwise comparisons between three groups by the number of metastatic lymph node (P < .001 for 0 vs 1‐2 and P = .003 for 1–2 vs ≥3).

Conclusion

Our data suggest lymph node classification as N0 (patients without lymph node metastases), N1 (metastasis in 1–2 regional lymph nodes), and N2 (metastases in ≥3 regional lymph nodes).
Facile one‐pot, three‐component synthesis of novel bis(heterocycles) incorporating thieno[2,3‐b]thiophenes via Michael addition reaction
Authors: Eid Elshimaa M. , Hassaneen Huwaida M. E. , Abdelhamid Ismail A. , Elwahy Ahmed H. M.
Published: March 2020

A synthesis of novel series of bis(2‐amino‐3‐cyano‐4H‐chromene), bis(2‐amino‐3‐cyanopyrano[3,2‐c]chromene), bis(6‐amino‐5‐cyano‐1,4‐dihydropyrano[2,3‐c]pyrazole), and bis(2,7‐diamino‐3,4,6‐tricyanopyrazolo[1,5‐a]pyridine) derivatives linked to thieno[2,3‐b]thiophene core via ether or ester linkages was reported. The formation of the target compounds presumably proceeds through a three component reaction of the appropriate bis(aldehyde) with 2 M of each of malononitrile and the corresponding active methylene compounds namely; dimedone, 4‐hydroxycoumarine, 5‐methyl‐2,4‐dihydro‐3H‐pyrazol‐3‐one, or cyanomethylpyrazole in dioxane at reflux in the presence of piperdine as a basic catalyst. The chemical structures of the new compounds were elucidated by several spectral tools.
Cytomegalovirus, Epstein‐Barr virus, and human herpesvirus‐6 infections in patients with myalgic еncephalomyelitis/chronic fatigue syndrome
Authors: Shikova Evelina , Reshkova Valentina , Kumanova Аntoniya , Raleva Sevdalina , Alexandrova Dora , Capo Natasa , Murovska Modra , on behalf of the European Network on ME/CFS (EUROMENE)
Published: March 2020

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disabling multisystem chronic disease. The etiology and pathogenesis of ME/CFS are unknown. Infections of cytomegalovirus (CMV), Epstein‐Barr virus (EBV), and human herpesvirus‐6 (HHV‐6) are suspected as etiological agents for ME/CFS. This study aims to estimate prevalence and type (active/latent) of EBV, CMV, and HHV‐6 infections in Bulgarian ME/CFS patients. In the study were included 58 patients with ME/CFS and 50 healthy controls. Virus‐specific antibodies were detected by enzyme‐linked immunosorbent assay and viral genomic sequences in peripheral blood mononuclear cell (PBMCs) and plasma samples by nested polymerase chain reaction (PCR). We did not observe any significant differences in virus‐specific immunoglobulin G and immunoglobulin M positivity rates between patients with ME/CFS and control group. In ME/CFS plasma samples, EBV DNA was found in 24.1%, CMV DNA in 3.4%, and HHV‐6 DNA in 1.7% of samples. EBV DNA was detected in 4%, and CMV and HHV‐6 DNA were not found in plasma samples of controls. The frequency of viral genome detection in PBMCs of patients and controls was 74% vs 78% for CMV, 81% vs 84% for EBV, and 82.8% vs 82% for HHV‐6. The difference in frequency of EBV active infection in ME/CFS and control group was statistically significant (P = .0027). No ME/CFS and control individuals with active CMV and HHV‐6 infection were observed. In conclusion, this study using both serological and PCR‐based techniques for distinguishing between active and latent infection showed high rate of active EBV infection among patients with ME/CFS indicating that at least in a subset of cases, EBV is important factor for the development of disease.
Circadian rhythms in the mouse reproductive axis during the estrous cycle and pregnancy
Authors: Yaw Alexandra M. , Duong Thu V. , Nguyen Duong , Hoffmann Hanne M.
Published: March 2020

Molecular and behavioral timekeeping is regulated by the circadian system which includes the brain's suprachiasmatic nucleus (SCN) that translates environmental light information into neuronal and endocrine signals aligning peripheral tissue rhythms to the time of day. Despite the critical role of circadian rhythms in fertility, it remains unexplored how circadian rhythms change within reproductive tissues during pregnancy. To determine how estrous cycle and pregnancy impact phase relationships of reproductive tissues, we used PER2::Luciferase (PER2::LUC) circadian reporter mice and determined the time of day of PER2::LUC peak (phase) in the SCN, pituitary, uterus, and ovary. The relationships between reproductive tissue PER2::LUC phases changed throughout the estrous cycle and late pregnancy and were accompanied by changes to PER2::LUC period in the SCN, uterus, and ovary. To determine if the phase relationship adaptations were driven by sex steroids, we asked if progesterone, a hormone involved in estrous cyclicity and pregnancy, could regulate Per2‐luciferase expression. Using an in vitro transfection assay, we found that progesterone increased Per2‐luciferase expression in immortalized SCN (SCN2.2) and arcuate nucleus (KTAR) cells. In addition, progesterone shortened PER2::LUC period in ex vivo uterine tissue recordings collected during pregnancy. As progesterone dramatically increases during pregnancy, we evaluated wheel‐running patterns in PER2::LUC mice. We confirmed that activity levels decrease during pregnancy and found that activity onset was delayed. Although SCN, but not arcuate nucleus, PER2::LUC period changed during late pregnancy, onset of locomotor activity did not correlate with SCN or arcuate nucleus PER2::LUC period.
Rare variants and biological pathways identified in treatment‐refractory depression
Authors: McClain Lora Lee , Shaw Patricia , Sabol Roisin , Chedia Anna Maria , Segretti Anna Maria , Rengasamy Manivel , Finegold David N. , Pan Lisa , Peters David Gerard
Published: March 2020

Individuals diagnosed with major depressive disorder not responding to at least two adequate treatments are defined as treatment‐refractory major depressive disorder (TR‐MDD). Some TR‐MDD patients have altered metabolic phenotypes that may be pharmacologically reversed. The characterization of these phenotypes and their underlying etiologies is paramount, particularly their genetic components. In this study, TR‐MDD patients (n = 124) were recruited and metabolites were quantified in their cerebrospinal fluid (CSF) and peripheral blood. Three sub‐categories of deficiencies were examined, namely 5‐methyltetrahydrofolte (in CSF; n = 13), tetrahydrobiopterin (in CSF; n = 11), and abnormal acylcarnitine profiles (in peripheral blood; n = 8). Whole exome sequencing was performed on genomic DNA from the entire TR‐MDD cohort and exonic variant allele frequencies for cases were compared to a control cohort (1:5 matching on ancestry). Low frequency, damaging alleles were identified and used for in silico pathway analyses. Three association signals for TR‐MDD approached genome‐wide significance on chromosomes 22, 7, and 3. Three risk‐associated variants from a prior depression study were replicated. Relevant biological pathways were identified that contained an enrichment of rare, damaging variants in central nervous system (CNS)‐specific pathways, including neurotransmitter receptors, potassium channels, and synapse transmission. Some TR‐MDD patients had rare variants in genes that were previously associated with other psychiatric disorders, psychiatric endophenotypes, CNS structural defects, and CNS‐related cellular and molecular functions. Exome analysis of metabolically phenotyped TR‐MDD patients has identified potentially functional gene pathways and low frequency, deleterious gene variants for further investigation. Further studies in larger cohorts of biochemically phenotyped TR‐MDD patients are desirable to extend and confirm these findings.
A newly isolated Streptomyces rimosus strain capable of degrading deltamethrin as a pesticide in agricultural soil
Authors: Khajezadeh Masoud , Abbaszadeh‐Goudarzi Kazem , Pourghadamyari Hossein , Kafilzadeh Farshid
Published: March 2020

Chemical pesticides or insecticides with complex structures are highly abundant in the biosphere and have inevitable side effects on farmland, natural resources, and human health. Deltamethrin is the most popular and widely used pesticide that disrupts the cellular calcium channels. In the present study, isolated strains of bacteria were examined to determine the ones that were capable of degrading deltamethrin. Different species of bacteria were evaluated in terms of the capability to degrade deltamethrin. It is important to note that Streptomyces rimosus was able to degrade up to 200 mg/L deltamethrin concentration and could be grown in mineral salt medium agar containing deltamethrin to be used as a source of carbon and energy. The results demonstrated that there is a diversity of deltamethrin‐degrading bacteria in agricultural soil ecosystems. The application of these bacteria, especially S. rimosus, might be used as a bioremediation technique to decrease pesticide contamination of the ecosystem.
Comparison between two rabbit models of posttraumatic osteoarthritis: A longitudinal tear in the medial meniscus and anterior cruciate ligament transection
Authors: Huang Kai , Cai Hai‐li , Zhang Peng‐li , Wu Li‐dong
Published: March 2020

Animal osteoarthritis (OA) models have been developed to understand OA progression and evaluate new OA therapies. However, individual variations in joint lesions remain a critical problem in most current OA models. We established a novel rabbit model by creating a longitudinal tear in the medial meniscus body that was reproducible and similar to posttraumatic biomechanical disturbances in human OA. New Zealand rabbits underwent surgery and were assessed for 9 weeks. The rabbits were randomized into the sham control, medial meniscal tear (MMT), and anterior cruciate ligament transection (ACLT) groups. The animals were sacrificed at 4, 6, and 9 weeks posttreatment. The knee joints were harvested for histological and gene expression assessments. Both the MMT and ACLT procedures led to time‐dependent degenerative changes in the femoral condyle cartilage. At each time point, the MMT group cartilage showed more severe degenerative changes than did the ACLT group cartilage. Consistently, inflammatory cytokine and catabolic gene expression were significantly higher, and anabolic gene expression was significantly lower in the MMT group than in the ACLT group. MMT treatment caused more severe structural damage to the cartilage and higher catabolic gene expression levels than the ACLT model at each time point. The MMT model may be highly beneficial in investigating posttraumatic OA (PTOA) development, especially PTOA from a meniscal injury. The MMT model replicated key features of human PTOA, including meniscal lesions, inflammatory responses, and the progression to osteoarthritic cartilage degeneration, thereby providing an exciting new avenue for translating promising treatments to clinical practice.
Addition of [18F]Fluorodeoxyglucose Positron Emission Tomography With Computed Tomography to Cross‐Sectional Imaging Improves Staging and Alters Management in Hepatocellular Carcinoma
Authors: John Binu V. , Aubuchon Sean , Dahman Bassam , Konjeti Venkata Rajesh , Heuman Douglas , Hubert Jennifer , Thomas Smitha , Deng Yangyang , Solomon Cynthia , Sundaram Latha Thankam , Love Eleanor , Singal Amit G. , Tatum James L.
Published: March 2020

In this work, we characterize the value of positron emission tomography (PET) with computed tomography (CT) in combination with cross‐sectional imaging for staging and prognostication of hepatocellular carcinoma (HCC) patients. In this retrospective cohort study, HCC patients underwent PET‐CT after initial staging with contrast‐enhanced CT or magnetic resonance imaging (MRI). The benefit of PET‐CT was measured by the identification of new HCC lesions, and potential harm was quantified by the number of false positives and subsequent diagnostic evaluation. We used multivariate Cox regression analysis to evaluate the association between the highest grade on PET‐CT with the risk of extrahepatic metastasis, progression‐free, and overall survival. Among 148 patients, PET‐CT detected additional extrahepatic metastasis in 11.9% of treatment‐naïve and 13.8% of treatment‐experienced patients. PET‐CT changed the Barcelona Clinic Liver Cancer (BCLC) staging in 5.9% of treatment‐naïve and 18.8% of treatment‐experienced patients compared with CT/MRI alone, changing HCC management in 9.9% and 21.3% of patients, respectively. Of the patients, 5% (n = 8) experienced severe physical harm requiring additional procedures to evaluate extrahepatic findings. High tumor grade on PET‐CT was independently associated with a higher likelihood of extrahepatic metastasis (hazard ratio [HR], 17.1; 95% confidence interval [CI], 3.6‐81.5) and worse overall survival (HR, 2.4; 95% CI, 1.4‐4.3). Treatment‐experienced patients (versus treatment‐naïve patients; HR, 9.7; 95% CI, 1.9‐49.4) and BCLC stage A (HR, 8.2; 95% CI, 1.5‐45.9; P < 0.01) and BCLC stage B (HR, 20.6; 95% CI, 1.5‐282.2; P < 0.05) were more likely to have an upstaging with PET‐CT compared with BCLC stage C (reference). PET‐CT provides prognostic information and improves tumor staging beyond CT/MRI alone, with subsequent changes in management for patients with HCC.
Two‐weight norm inequalities for fractional maximal functions and fractional integral operators on weighted Morrey spaces
Authors: Pan Junren , Sun Wenchang
Published: March 2020

In this paper, we consider weighted norm inequalities for fractional maximal operators and fractional integral operators. For suitable weights, we prove the two‐weight norm inequalities for both operators on weighted Morrey spaces.
Composition, diversity, and activity of aerobic ammonia‐oxidizing Bacteria and Archaea in the intertidal sands of a grand strand South Carolina beach
Authors: Taylor Harrison B. , Kurtz Harry D.
Published: March 2020

Aerobic ammonia oxidation to nitrite has been established as an important ecosystem process in regulating the level of nitrogen in marine ecosystems. This process is carried out by ammonia‐oxidizing bacteria (AOB) within the classes Betaproteobacteria and Gammaproteobacteria and ammonia‐oxidizing Archaea (AOA) from the phylum Thaumarchaeota, and the latter of which has been established as more prevalent in marine systems. This study investigated the presence, abundance, and activity of these groups of microbes at a beach near Springmaid Pier in Myrtle Beach, South Carolina, through the implementation of next generation sequencing, quantitative PCR (qPCR), and microcosm experiments to monitor activity. Sequencing analysis revealed a diverse community of ammonia‐oxidizing microbes dominated by AOA classified within the family Nitrosopumilaceae, and qPCR revealed the abundance of AOA amoA genes over AOB by at least an order of magnitude in most samples. Microcosm studies indicate that the rates of potential ammonia oxidation in these communities satisfy Michaelis–Menten substrate kinetics and this process is more active at temperatures corresponding to summer months than winter. Potential rates in AOA medium were higher than that of AOB medium, indicating a potentially greater contribution of AOA to this process in this environment. In conclusion, this study provides further evidence of the dominance of AOA in these environments compared with AOB and highlights the overall efficiency of this process at turning over excess ammonium that may be present in these environments.
Technical Note: The development of a multi‐physics simulation tool to estimate the background dose by systemic targeted alpha therapy
Authors: Xu T. , Liu T. , Li G. , Dugal C. , Aydemir N. A. , Liu Y. , Roeske J. C.
Published: March 2020

Purpose

To predict biological effects of targeted alpha therapy (TAT) in preclinical studies, dosimetry calculations based on the micro‐level distributions of emitters are essential. Due to the saturation of the tumor antigenic sites and bonding breaks by decay, some of Alpha‐immuno‐conjugate and decay daughters may inevitably be transported by convection and diffusion along with blood or lymphatic circulation. This results in highly nonuniform and unsteady distributions of irradiation sources. Since the micro‐level distribution of emitters cannot be measured and obtained in patients with current technology, a modeling toolset to give more insight of the internal dose could be an alternative.

Methods

A multi‐physics model based on a Monte Carlo microdosimetry technique and computational fluid dynamics (CFD) modeling was developed and applied to multiple internal irradiation sources. The CFD model tracks the path of the radionuclides and the dose model is capable of evaluating the time‐dependent absorbed dose to the target.

Results

The conceptual model is capable of handling complex nonuniform irradiation sources in vasculature. The results from the simulations indicate that the assumption of homogeneous and motionless distribution of the administered activity used in the conventional dose calculation tends to significantly underestimate or overestimate the absorbed dose to the vascular system in various scenarios.

Conclusion

Modeling the in vivo transport of radionuclides has the potential to improve the accuracy of TAT dose estimates. It could be the first step to develop a simulation tool set for assessing absorbed dose to tumor or normal tissues and predict the corresponding biological responses in the future.
Pushing functional MRI spatial and temporal resolution further: High‐density receive arrays combined with shot‐selective 2D CAIPIRINHA for 3D echo‐planar imaging at 7 T
Authors: Hendriks Arjan D. , D'Agata Federico , Raimondo Luisa , Schakel Tim , Geerts Liesbeth , Luijten Peter R. , Klomp Dennis W.J. , Petridou Natalia
Published: March 2020

To be able to examine dynamic and detailed brain functions, the spatial and temporal resolution of 7 T MRI needs to improve. In this study, it was investigated whether submillimeter multishot 3D EPI fMRI scans, acquired with high‐density receive arrays, can benefit from a 2D CAIPIRINHA sampling pattern, in terms of noise amplification (g‐factor), temporal SNR and fMRI sensitivity. High‐density receive arrays were combined with a shot‐selective 2D CAIPIRINHA implementation for multishot 3D EPI sequences at 7 T. In this implementation, in contrast to conventional inclusion of extra kz gradient blips, specific EPI shots are left out to create a CAIPIRINHA shift and reduction of scan time. First, the implementation of the CAIPIRINHA sequence was evaluated with a standard receive setup by acquiring submillimeter whole brain T2*‐weighted anatomy images. Second, the CAIPIRINHA sequence was combined with high‐density receive arrays to push the temporal resolution of submillimeter 3D EPI fMRI scans of the visual cortex. Results show that the shot‐selective 2D CAIPIRINHA sequence enables a reduction in scan time for 0.5 mm isotropic 3D EPI T2*‐weighted anatomy scans by a factor of 4 compared with earlier reports. The use of the 2D CAIPIRINHA implementation in combination with high‐density receive arrays, enhances the image quality of submillimeter 3D EPI scans of the visual cortex at high acceleration as compared to conventional SENSE. Both the g‐factor and temporal SNR improved, resulting in a method that is more sensitive to the fMRI signal. Using this method, it is possible to acquire submillimeter single volume 3D EPI scans of the visual cortex in a subsecond timeframe. Overall, high‐density receive arrays in combination with shot‐selective 2D CAIPIRINHA for 3D EPI scans prove to be valuable for reducing the scan time of submillimeter MRI acquisitions.
Non‐Hermitian perturbations of Hermitian matrix‐sequences and applications to the spectral analysis of the numerical approximation of partial differential equations
Authors: Barbarino Giovanni , Serra‐Capizzano Stefano
Published: March 2020

This article concerns the spectral analysis of matrix‐sequences which can be written as a non‐Hermitian perturbation of a given Hermitian matrix‐sequence. The main result reads as follows. Suppose that for every n there is a Hermitian matrix Xn of size n and that {Xn}n∼λf, that is, the matrix‐sequence {Xn}n enjoys an asymptotic spectral distribution, in the Weyl sense, described by a Lebesgue measurable function f; if with ‖·‖2 being the Schatten 2 norm, then {Xn+Yn}n∼λf. In a previous article by Leonid Golinskii and the second author, a similar result was proved, but under the technical restrictive assumption that the involved matrix‐sequences {Xn}n and {Yn}n are uniformly bounded in spectral norm. Nevertheless, the result had a remarkable impact in the analysis of both spectral distribution and clustering of matrix‐sequences arising from various applications, including the numerical approximation of partial differential equations (PDEs) and the preconditioning of PDE discretization matrices. The new result considerably extends the spectral analysis tools provided by the former one, and in fact we are now allowed to analyze linear PDEs with (unbounded) variable coefficients, preconditioned matrix‐sequences, and so forth. A few selected applications are considered, extensive numerical experiments are discussed, and a further conjecture is illustrated at the end of the article.
Impact of Exposure to Antibiotics During Pregnancy and Infancy on Childhood Obesity: A Systematic Review and Meta‐Analysis
Authors: Wan Shengrong , Guo Man , Zhang Ting , Chen Qing , Wu Maoyan , Teng Fangyuan , Long Yang , Jiang Zongzhe , Xu Yong
Published: March 2020

Objective

This study aimed to investigate whether antibiotic exposure during pregnancy and infancy was associated with childhood overweight or obesity.

Methods

PubMed, Embase, and Cochrane Library databases were searched from the inception date to April 18, 2019, to identify observational studies that investigated the association between antibiotic exposure during pregnancy and infancy and childhood overweight or obesity. After study selection and data extraction, the meta‐analysis was conducted using Stata software version 12.0 (StataCorp LP, College Station, Texas). The evaluation of the methodological quality was carried out by AMSTAR 2 (Bruyère Research Institute, Ottawa, Ontario, Canada).

Results

A total of 23 observational studies involving 1,253,035 participants were included. The meta‐analysis showed that prenatal exposure to antibiotics was not significantly associated with childhood overweight or obesity, whereas an increased risk of overweight or obesity was seen in subgroup analysis of the second trimester (risk ratio = 1.13; 95% CI: 1.06‐1.22; P = 0.001). In contrast, antibiotic exposure during infancy could increase the risk of childhood overweight or obesity (risk ratio = 1.14; 95% CI: 1.06‐1.23; P = 0.001).

Conclusions

This meta‐analysis found that antibiotic exposure during the second trimester and infancy could increase the risk of childhood overweight or obesity.
A mini review on the generation of crimped ultrathin fibers via electrospinning: Materials, strategies, and applications
Authors: Zaarour Bilal , Zhu Lei , Huang Chen , Jin Xiangyu
Published: March 2020

Structures modification of fibers has been attracting significant attention in various fields and applications. Among different techniques of fabricating ultrathin fibers, electrospinning is the most commonly adopted method because of the ease of forming fibers with a wide range of properties and its exceptional advantages, such as the ability to spin into different shapes and sizes, as well as the adaptable porosity of electrospun fiber webs. The crimped structure has been attracting the attention of scientific researchers owing to its unique properties (eg, spring‐like behavior, supreme strain, remarkable specific surface area, good piezoelectric properties, excellent biological properties, and so on). Therefore, this study summarizes a review of the strategies and methods, reported so far, of generating electrospun crimped ultrathin fibers of various polymers. The review focuses on the polymer types, formation methods, characterizations, and applications of the electrospun crimped ultrathin fibers. We believe this work can serve as an important reference for the materials, strategies, and applications of crimped fibers.
Thermal latent curing agent for epoxy resins from neutralization of 2‐methylimidazole with a phosphazene‐containing polyfunctional carboxylic acid
Authors: Wei Wei , Sun Xin , Ye Weitao , Zhang Bowen , Fei Xiaoma , Li Xiaojie , Liu Xiaoya
Published: March 2020

A novel thermal latent curing agent, 2MZS, was obtained through the reaction of 2‐methylimidazole (2MZ) and a symmetrically carboxyl‐functionalized star‐shaped molecule based on cyclotriphosphazene (N3P3‐COOH). In the complex, the resonance of N3P3‐COOH reduced the activity of lone electron pairs on the pyridine‐type nitrogen atom of imidazole ring, suppressing the nucleophilic attack and crosslinking reaction between 2MZ and epoxy resin. As a result, the storage stability was improved distinctly for the one‐pot epoxy compound, which could be steadily stored at room temperature for nearly 1 month. Nonisothermal DSC revealed a delayed initiation curing mechanism of the prepared one‐pot system, and which could undergo rapid curing reaction upon raising the temperature. Moreover, the introduction of terminally polyfunctional star‐shaped phosphazene derivative could promote the curing process at elevated temperature, as well as improve the chain rigidity of the cured resin by chemical incorporation into the cross‐linked network, thus endowing the cured resin with enhanced glassy storage modulus. The epoxy thermoset exhibited the highest glass transition temperature and thermal degradation temperature when 20 wt% of 2MZS was used. It is suggested that the novel latent curing agent is potential for high‐performance one‐pot epoxy compound, particularly recommended for application in electronic packaging fields.
Measurements of the sediment flocculation characteristics in the Three Gorges Reservoir, Yangtze River
Authors: Li Wenjie , Yu Chengfeng , Yang Shengfa , Yang Yunping , Yang Wei , Xiao Yi
Published: March 2020

The flocculation of fine sediments in the Three Gorges Reservoir (TGR) was confirmed in previous studies, but the flocculation characteristics have yet to be fully clarified. In this study, field measurements were conducted in the TGR to investigate the sediment flocculation characteristics. First, the instantaneous flow velocity and sediment concentration were measured through Acoustic Doppler velocimeter and sediment sampling. Then, the effective settling velocity was calculated based on the sediment diffusion theory to deduce the floc size and flocculation degree. Finally, the influences of particle size, flow velocity, and sediment concentration on flocculation were analyzed. Results showed that flocculation occurred in more than half of the sediments in the TGR, and the maximum flocculation degree was between 10 and 30. Flocculation weakened as particle diameter increased, with the critical particle size being approximately 0.018 mm, meaning that flocculation was unlikely to occur when the particle size exceeded the critical value. As the flow velocity increased, the flocculation degree first increased and then decreased, with the critical flow velocity being approximately 0.7 m/s, but the critical flow velocity increased with an increase in sediment concentration and tended to be a constant. The flocculation degree also increased with increasing sediment concentration and tended to be constant when the sediment concentration exceeded approximately 0.5 kg/m3. The results provide new information on the flocculation characteristics of the TGR and should be useful for understanding and simulating fine sediment transport in the TGR.
People refusing to be wealth: What happens when South African workers are denied access to “belonging in”
Authors: Jeske Christine
Published: March 2020

Research on wealth‐in‐people has proven useful for studying relationships between employers and employees in capitalist systems, but scholars have largely ignored an idea introduced alongside the concept of wealth‐in‐people in Igor Kopytoff and Suzanne Miers's foundational 1977 study. Namely, these authors describe a continuum of ways in which people who are “wealth” to others become either included into or excluded from the groups benefiting from and controlling that wealth. In this article, I use that continuum to examine workplace relationships in South Africa that fall on the exclusion end of the continuum, where discrimination, lack of training and advancement opportunities, and bureaucratic distancing prevent workers from “belonging in” workplace power structures. Drawing on twelve months of fieldwork in low‐wage workplaces and surrounding communities in KwaZulu‐Natal, South Africa, I argue that many workers in such settings respond by withholding their loyalty from employers, thereby limiting the extent to which they will “belong to” employers as wealth‐in‐people. This article sheds light on a popular discourse in South Africa and elsewhere that has criticized low‐waged and unemployed workers for refusing to be model workers. Such workers follow a logic of refusing to “belong to” when they are denied opportunities to “belong in,” thereby heightening one form of estrangement while potentially resisting another.
A general frailty model to accommodate individual heterogeneity in the acquisition of multiple infections: An application to bivariate current status data
Authors: Tran Thao M.P. , Abrams Steven , Braekers Roel
Published: March 2020

The analysis of multivariate time‐to‐event (TTE) data can become complicated due to the presence of clustering, leading to dependence between multiple event times. For a long time, (conditional) frailty models and (marginal) copula models have been used to analyze clustered TTE data. In this article, we propose a general frailty model employing a copula function between the frailty terms to construct flexible (bivariate) frailty distributions with the application to current status data. The model has the advantage to impose a less restrictive correlation structure among latent frailty variables as compared to traditional frailty models. Specifically, our model uses a copula function to join the marginal distributions of the frailty vector. In this article, we considered different copula functions, and we relied on marginal gamma distributions due to their mathematical convenience. Based on a simulation study, our novel model outperformed the commonly used additive correlated gamma frailty model, especially in the case of a negative association between the frailties. At the end of the article, the new methodology is illustrated on real‐life data applications entailing bivariate serological survey
data.
Cryopreservation of DNA Origami Nanostructures
Authors: Xin Yang , Kielar Charlotte , Zhu Siqi , Sikeler Christoph , Xu Xiaodan , Möser Christin , Grundmeier Guido , Liedl Tim , Heuer‐Jungemann Amelie , Smith David M. , Keller Adrian
Published: March 2020

Although DNA origami nanostructures have found their way into numerous fields of fundamental and applied research, they often suffer from rather limited stability when subjected to environments that differ from the employed assembly conditions, that is, suspended in Mg2+‐containing buffer at moderate temperatures. Here, means for efficient cryopreservation of 2D and 3D DNA origami nanostructures and, in particular, the effect of repeated freezing and thawing cycles are investigated. It is found that, while the 2D DNA origami nanostructures maintain their structural integrity over at least 32 freeze–thaw cycles, ice crystal formation makes the DNA origami gradually more sensitive toward harsh sample treatment conditions. Whereas no freeze damage could be detected in 3D DNA origami nanostructures subjected to 32 freeze–thaw cycles, 1000 freeze–thaw cycles result in significant fragmentation. The cryoprotectants glycerol and trehalose are found to efficiently protect the DNA origami nanostructures against freeze damage at concentrations between 0.2 × 10−3 and 200 × 10−3 m and without any negative effects on DNA origami shape. This work thus provides a basis for the long‐term storage of DNA origami nanostructures, which is an important prerequisite for various technological and medical applications.
Micro‐/Nanomotors toward Biomedical Applications: The Recent Progress in Biocompatibility
Authors: Ou Juanfeng , Liu Kun , Jiang Jiamiao , Wilson Daniela A. , Liu Lu , Wang Fei , Wang Shuanghu , Tu Yingfeng , Peng Fei
Published: March 2020

Inspired by the highly versatile natural motors, artificial micro‐/nanomotors that can convert surrounding energies into mechanical motion and accomplish multiple tasks are devised. In the past few years, micro‐/nanomotors have demonstrated significant potential in biomedicine. However, the practical biomedical applications of these small‐scale devices are still at an infant stage. For successful bench‐to‐bed translation, biocompatibility of micro‐/nanomotor systems is the central issue to be considered. Herein, the recent progress in micro‐/nanomotors in biocompatibility is reviewed, with a special focus on their biomedical applications. Through close collaboration between researches in the nanoengineering, material chemistry, and biomedical fields, it is expected that a promising real‐world application platform based on micro‐/nanomotors will emerge in the near future.
Decision‐making for the efficient life cycle management of structures
Authors: Zimmert Florian , Braml Thomas , Keuser Manfred
Published: March 2020

Structures made of structural concrete are designed to withstand different time‐dependent or time‐independent influences during their expected service lifetime. Most of these influences can be considered in a sufficient manner by mathematical and statistical approaches, while some do appear combined with certain structural, environmental, and material boundary conditions. These can, in most cases, not be foreseen, verified or they change during the lifecycle of a concrete structure. It is therefore obligatory to rely on an efficient conservation strategy for each structure to ensure its safety and overall economic efficiency. For this purpose, the fib Model Code for Concrete Structures 2010 already suggests a general workflow to follow a predefined or provisional conservation strategy and condition control procedure. These existing proposals are yet of very general nature and disclaim practical decision‐making rules to survey and assess existing structures as part of a condition‐based conservation strategy. In this contribution, the main decision‐making options at an early stage of a construction's life cycle management are pointed out, considering their importance for a structure's time‐dependent performance and their relation to continuative decisions for conservation management. Proposals for the implementation of practical advice for condition‐based conservation strategies in international guidelines are made.
Experimental evaluation of punching shear capacity of reinforced concrete slabs with horizontal crack due to compression rebar corrosion
Authors: Ikehata Shinya , Ishiguro Hirotaka , Nakano Takato , Nakamura Hikaru
Published: March 2020

Punching shear capacity of deteriorated reinforced concrete slab is experimentally investigated in this study. Since horizontal crack near the upper side rebar is often observed in deteriorated reinforced concrete bridge deck slabs due to rebar corrosion, horizontal crack propagation behavior was investigated by accelerated electric corrosion test. Then, in order to evaluate the influence of the horizontal crack on punching shear capacity of slabs, loading tests were carried out using the test specimens with the corrosion‐induced crack and with an artificial horizontal crack. According to the test results, the horizontal crack near the upper side rebar has a significant impact on punching shear capacity of slabs, and it is confirmed that punching shear capacity of reinforced concrete slab correlates to the width of the horizontal crack. Also, it is revealed that cover concrete above horizontal crack does not effectively work if width of the horizontal crack grows to a certain amount.
Transcription and splicing: A two‐way street
Authors: Tellier Michael , Maudlin Isabella , Murphy Shona
Published: March 2020

RNA synthesis by RNA polymerase II and RNA processing are closely coupled during the transcription cycle of protein‐coding genes. This coupling affords opportunities for quality control and regulation of gene expression and the effects can go in both directions. For example, polymerase speed can affect splice site selection and splicing can increase transcription and affect the chromatin landscape. Here we review the many ways that transcription and splicing influence one another, including how splicing "talks back" to transcription. We will also place the connections between transcription and splicing in the context of other RNA processing events that define the exons that will make up the final mRNA.

This article is categorized under:

RNA Processing > Splicing Mechanisms

RNA Processing > Splicing Regulation/Alternative Splicing
Modeling immune cell behavior across scales in cancer
Authors: Makaryan Sahak Z. , Cess Colin G. , Finley Stacey D.
Published: March 2020

Detailed, mechanistic models of immune cell behavior across multiple scales in the context of cancer provide clinically relevant insights needed to understand existing immunotherapies and develop more optimal treatment strategies. We highlight mechanistic models of immune cells and their ability to become activated and promote tumor cell killing. These models capture various aspects of immune cells: (a) single‐cell behavior by predicting the dynamics of intracellular signaling networks in individual immune cells, (b) multicellular interactions between tumor and immune cells, and (c) multiscale dynamics across space and different levels of biological organization. Computational modeling is shown to provide detailed quantitative insight into immune cell behavior and immunotherapeutic strategies. However, there are gaps in the literature, and we suggest areas where additional modeling efforts should be focused to more prominently impact our understanding of the complexities of the immune system in the context of cancer.

This article is categorized under:

Biological Mechanisms > Cell Signaling

Models of Systems Properties and Processes > Mechanistic Models

Models of Systems Properties and Processes > Cellular Models
Bounds in Cohen’s Idempotent Theorem
Authors: Sanders Tom
Published: March 2020

Suppose that G is a finite Abelian group and write $${\mathcal {W}}(G)$$W(G) for the set of cosets of subgroups of G. We show that if $$f:G \rightarrow {\mathbb {Z}}$$f:G→Z satisfies the estimate $$\Vert f\Vert _{A(G)} \le M$$‖f‖A(G)≤M with respect to the Fourier algebra norm, then there is some $$z:{\mathcal {W}}(G) \rightarrow {\mathbb {Z}}$$z:W(G)→Z such that $$\begin{aligned} f=\sum _{W \in {\mathcal {W}}(G)}{z(W)1_W}\quad \text { and }\quad \Vert z\Vert _{\ell _1({\mathcal {W}}(G))} =\exp (M^{4+o(1)}). \end{aligned}$$f=∑W∈W(G)z(W)1Wand‖z‖ℓ1(W(G))=exp(M4+o(1)).
Urinary incontinence in a fitness club setting—is it a workout problem?
Authors: Haakstad Lene A. H. , Gjestvang Christina , Lamerton Tayla , Bø Kari
Published: March 2020

Introduction

The aims of the present study were to report longitudinal data on the prevalence of urinary incontinence (UI) in a fitness club setting and to investigate whether gym members are educated about and exercise their pelvic floor muscles.

Methods

New members (125 women) from 25 fitness clubs in Oslo, Norway, filled in a 25-min online questionnaire (SurveyXact) at four time points (onset, 3, 6 and 12 months of fitness club membership). The questionnaire covered background/health information, membership dropout and exercise habits, including pelvic floor muscle training (PFMT). A modified Subjective Health Complaints Inventory (SHC Inventory) and the International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form (ICIQ-UI SF) were used to gather repeated measures of UI.

Results

At onset, 3, 6 and 12 months of fitness club membership, 16.8%, 13.8%, 19.6% and 18.7% reported UI, respectively (p = 0.11). Of these, 57.1% to 76.2% reported leakage during exercise and perceived the UI to be slight. Less than 8% had received information about PFMT by the fitness club staff. Adherence to regular exercise and PFMT throughout the follow-up period (minimum two sessions/week) did not show any association with absent or present UI at 12 months (p = 0.48 and p = 0.63) and was reported by 30% and 22.2% of the participants, respectively.

Conclusions

About 17% reported UI at onset of fitness club membership, with no changes in proportions throughout the first year. Adherence to regular exercise and PFMT did not show any association with absent or present UI at 12 months. Few had been taught PFMT.
Harmonic tropical morphisms and approximation
Authors: Lang Lionel
Published: March 2020

Harmonic amoebas are generalisations of amoebas of algebraic curves immersed in complex tori. Introduced by Krichever in 2014, the consideration of such objects suggests to enlarge the scope of tropical geometry. In the present paper, we introduce the notion of harmonic morphisms from tropical curves to affine spaces and show how these morphisms can be systematically described as limits of families of harmonic amoeba maps on Riemann surfaces. It extends previous results about approximation of tropical curves in affine spaces and provides a different point of view on Mikhalkin’s approximation Theorem for regular phase-tropical morphisms, as stated e.g. by Mikhalkin in 2006. The results presented here follow from the study of imaginary normalised differentials on families of punctured Riemann surfaces and suggest interesting connections with compactifications of moduli spaces.
Quantification of the dynamics of population heterogeneities in CHO cultures with stably integrated fluorescent markers
Authors: Möller Johannes , Rosenberg Marcel , Riecken Kristoffer , Pörtner Ralf , Zeng An-Ping , Jandt Uwe
Published: March 2020

Cell population heterogeneities and their changes in mammalian cell culture processes are still not well characterized. In this study, the formation and dynamics of cell population heterogeneities were investigated with flow cytometry and stably integrated fluorescent markers based on the lentiviral gene ontology (LeGO) vector system. To achieve this, antibody-producing CHO cells were transduced with different LeGO vectors to stably express single or multiple fluorescent proteins. This enables the tracking of the transduced populations and is discussed in two case studies from the field of bioprocess engineering: In case study I, cells were co-transduced to express red, green, and blue fluorescent proteins and the development of sub-populations and expression heterogeneities were investigated in high passage cultivations (total 130 days). The formation of a fast-growing and more productive population was observed with a simultaneous increase in cell density and product titer. In case study II, different preculture growth phases and their influence on the population dynamics were investigated in mixed batch cultures with flow cytometry (offline and automated). Four cell line derivatives, each expressing a different fluorescent protein, were generated and cultivated for different time intervals, corresponding to different growth phases. Mixed cultures were inoculated from them, and changes in the composition of the cell populations were observed during the first 48 h of cultivation with reduced process productivity. In summary, we showed how the dynamics of population heterogeneities can be characterized. This represents a novel approach to investigate the dynamics of cell population heterogeneities under near-physiological conditions with changing productivity in mammalian cell culture processes.