Mechanistic understanding of miscibility effects on fracture strength of polymer interfaces

This research has provided a fundamental framework based on both experiment and theory to understand the fracture behavior as a function of system miscibility for nonreinforced polymer interfaces. The system chosen for study was polystyrene (PS) and the statistically random copolymer poly (styrene-r-4-bromostyrene) (PBS), where the volume fraction of bromine in the copolymer, f, and the degree of polymerization, N, control the miscibility. The phase behavior of thin film blends of PS and PBS as a function of f and N was studied using atomic force microscopy (AFM) and small angle X-ray scattering (SAXS). Simulations based on the Flory-Huggins theory and the Flory-Huggins interaction parameter, chi, measured from SAXS were used to predict phase diagrams for all the systems studied. Using the phase diagrams, a miscibility map as a function of f, N, and the symmetry of N was developed and showed good agreement with compatibility (measured using AFM). A modified double cantilever beam geometry was employed to measure the Mode I fracture energy (Gc) of PS/PBS interfaces as a function of miscibility. The fracture surfaces were analyzed using scanning electron microscopy and optical microscopy to discern the failure mechanism. The fracture experiments showed that three interdiffusion/fracture regimes exist and that maximizing interfacial strength is based on the competition between gradient-driven and miscibility-limited interdiffusion and can be controlled by optimizing the miscibility of the system. Finally, a new stochastic model, which takes into consideration system miscibility, was developed to calculate Sigmaeff for partially miscible polymer interfaces. Based on this Sigmaeff, a new equation for fracture of non-reinforced systems was postulated which correctly predicts the transition from chain pullout to crazing. This equation incorporates system miscibility via Sigmaeff, the interfacial width, and the average distance between entanglements. As a function of system miscibility, the model also accurately predicts a maximum in Gc as a result of the competition between gradient-driven and miscibility limited interdiffusion. The use of the miscibility criterion proposed for the fracture mechanism may be the first step in revealing the universal nature of the pullout to crazing transition

SalmoNet, an integrated network of ten Salmonella enterica strains reveals common and distinct pathways to host adaptation

Salmonella enterica is a prominent bacterial pathogen with implications on human and animal health. Salmonella serovars could be classified as gastro-intestinal or extra-intestinal. Genome-wide comparisons revealed that extra-intestinal strains are closer relatives of gastro-intestinal strains than to each other indicating a parallel evolution of this trait. Given the complexity of the differences, a systems-level comparison could reveal key mechanisms enabling extra-intestinal serovars to cause systemic infections. Accordingly, in this work, we introduce a unique resource, SalmoNet, which combines manual curation, high-throughput data and computational predictions to provide an integrated network for Salmonella at the metabolic, transcriptional regulatory and protein-protein interaction levels. SalmoNet provides the networks separately for five gastro-intestinal and five extra-intestinal strains. As a multi-layered, multi-strain database containing experimental data, SalmoNet is the first dedicated network resource for Salmonella. It comprehensively contains interactions between proteins encoded in Salmonella pathogenicity islands, as well as regulatory mechanisms of metabolic processes with the option to zoom-in and analyze the interactions at specific loci in more detail. Application of SalmoNet is not limited to strain comparisons as it also provides a Salmonella resource for biochemical network modeling, host-pathogen interaction studies, drug discovery, experimental validation of novel interactions, uncovering new pathological mechanisms from emergent properties and epidemiological studies. SalmoNet is available at http://salmonet.org

Characterization of electrospun nanocomposite scaffolds and biocompatibility with adipose-derived human mesenchymal stem cells

Electrospun nanocomposite scaffolds were fabricated by encapsulating multi-walled carbon nanotubes (MWNT) in poly (lactic acid) (PLA) nanofibers. Scanning electron microscopy (SEM) confirmed the fabrication of nanofibers, and transmission electron microscopy identified the alignment and dispersion of MWNT along the axis of the fibers. Tensile testing showed an increase in the tensile modulus for a MWNT loading of 0.25 wt% compared with electrospun nanofibrous mats without MWNT reinforcement. Conductivity measurements indicated that the confined geometry of the fibrous system requires only minute doping to obtain significant enhancements at 0.32 wt%. Adipose-derived human mesenchymal stem cells (hMSCs) were seeded on electrospun scaffolds containing 1 wt% MWNT and 0 wt% MWNT, to determine the efficacy of the scaffolds for cell growth, and the effect of MWNT on hMSC viability and proliferation over two weeks in culture. Staining for live and dead cells and DNA quantification indicated that the hMSCs were alive and proliferating through day 14. SEM images of hMSCs at 14 days showed morphological differences, with hMSCs on PLA well spread and hMSCs on PLA with 1% MWNT closely packed and longitudinally aligned

Time to Continuous Renal Replacement Therapy Initiation and 90-Day Major Adverse Kidney Events in Children and Young Adults

IMPORTANCE: In clinical trials, the early or accelerated continuous renal replacement therapy (CRRT) initiation strategy among adults with acute kidney injury or volume overload has not demonstrated a survival benefit. Whether the timing of initiation of CRRT is associated with outcomes among children and young adults is unknown. OBJECTIVE: To determine whether timing of CRRT initiation, with and without consideration of volume overload (VO; DESIGN, SETTING, AND PARTICIPANTS: This multinational retrospective cohort study was conducted using data from the Worldwide Exploration of Renal Replacement Outcome Collaborative in Kidney Disease (WE-ROCK) registry from 2015 to 2021. Participants included children and young adults (birth to 25 years) receiving CRRT for acute kidney injury or VO at 32 centers across 7 countries. Statistical analysis was performed from February to July 2023. EXPOSURE: The primary exposure was time to CRRT initiation from intensive care unit admission. MAIN OUTCOMES AND MEASURES: The primary outcome was MAKE-90 (death, dialysis dependence, or persistent kidney dysfunction [\u3e25% decline in estimated glomerular filtration rate from baseline]). RESULTS: Data from 996 patients were entered into the registry. After exclusions (n = 27), 969 patients (440 [45.4%] female; 16 (1.9%) American Indian or Alaska Native, 40 (4.7%) Asian or Pacific Islander, 127 (14.9%) Black, 652 (76.4%) White, 18 (2.1%) more than 1 race; median [IQR] patient age, 8.8 [1.7-15.0] years) with data for the primary outcome (MAKE-90) were included. Median (IQR) time to CRRT initiation was 2 (1-6) days. MAKE-90 occurred in 630 patients (65.0%), of which 368 (58.4%) died. Among the 601 patients who survived, 262 (43.6%) had persistent kidney dysfunction. Of patients with persistent dysfunction, 91 (34.7%) were dependent on dialysis. Time to CRRT initiation was approximately 1 day longer among those with MAKE-90 (median [IQR], 3 [1-8] days vs 2 [1-4] days; P = .002). In the generalized propensity score-weighted regression, there were approximately 3% higher odds of MAKE-90 for each 1-day delay in CRRT initiation (odds ratio, 1.03 [95% CI, 1.02-1.04]). CONCLUSIONS AND RELEVANCE: In this cohort study of children and young adults receiving CRRT, longer time to CRRT initiation was associated with greater risk of MAKE-90 outcomes, in particular, mortality. These findings suggest that prospective multicenter studies are needed to further delineate the appropriate time to initiate CRRT and the interaction between CRRT initiation timing and VO to continue to improve survival and reduce morbidity in this population

Broadening Participation in Biology Education Research: Engaging Community College Students and Faculty

Nearly half of all undergraduates are enrolled at community colleges (CCs), including the majority of U.S. students who represent groups underserved in the sciences. Yet only a small minority of studies published in discipline-based education research journals address CC biology students, faculty, courses, or authors. This marked underrepresentation of CC biology education research (BER) limits the availability of evidence that could be used to increase CC student success in biology programs. To address this issue, a diverse group of stakeholders convened at the Building Capacity for Biology Education Research at Community Colleges meeting to discuss how to increase the prevalence of CC BER and foster participation of CC faculty as BER collaborators and authors. The group identified characteristics of CCs that make them excellent environments for studying biology teaching and learning, including student diversity and institutional cultures that prioritize teaching, learning, and assessment. The group also identified constraints likely to impede BER at CCs: limited time, resources, support, and incentives, as well as misalignment between doing research and CC faculty identities as teachers. The meeting culminated with proposing strategies for faculty, administrators, journal editors, scientific societies, and funding agencies to better support CC BER

A prospective cohort study of postoperative complications in the management of perforated peptic ulcer

BACKGROUND: With dwindling rates of postoperative mortality in perforated peptic ulcer that is attributable to H(2)-receptor blocker usage, there is a need to shift the focus towards the prevention of postoperative morbidity. Further, the simultaneous contribution of several putative clinical predictors to this postoperative morbidity is not fully appreciated. Our objective was to assess the predictors of the risk, rate and number of postoperative complications in surgically treated patients of perforated peptic ulcer. METHODS: In a prospective cohort study of 96 subjects presenting as perforated peptic ulcer and treated using Graham's omentoplatsy patch or gastrojejunostomy (with total truncal vagotomy), we assessed the association of clinical predictors with three domains of postoperative complications: the risk of developing a complication, the rate of developing the first complication and the risk of developing higher number of complications. We used multiple regression methods – logistic regression, Cox proportional hazards regression and Poisson regression, respectively – to examine the association of the predictors with these three domains. RESULTS: We observed that the risk of developing a postoperative complication was significantly influenced by the presence of a concomitant medical illness [odds ratio (OR) = 8.9, p = 0.001], abdominal distension (3.8, 0.048) and a need of blood transfusion (OR = 8.2, p = 0.027). Using Poisson regression, it was observed that the risk for a higher number of complications was influenced by the same three factors [relative risk (RR) = 2.6, p = 0.015; RR = 4.6, p < 0.001; and RR = 2.4, p = 0.002; respectively]. However, the rate of development of complications was influenced by a history suggestive of shock [relative hazards (RH) = 3.4, p = 0.002] and A(- )blood group (RH = 4.7, p = 0.04). CONCLUSION: Abdominal distension, presence of a concomitant medical illness and a history suggestive of shock at the time of admission warrant a closer and alacritous postoperative management in patients of perforated peptic ulcer

Determining Factors of the Level of Disclosure of Information on Business Combinations with the Entry into Force of the Accounting Standard CPC 15

This paper aimed to investigate information disclosure on business combination transactions that took place in Brazil in 2010, when the Accounting Standard CPC 15 entered into force, and evaluate which were the determining factors of the level of disclosure of information related to it. To evaluate the disclosure level, a disclosure index of business combinations (INDCOMB) was prepared, having the disclosure index developed by Shalev (2009) as a basis. We evaluated, in the light of the literature on disclosure and business combinations, whether the following factors influenced on the disclosure level: acquiring company size, recognized percentage of overprice for expected future profitability in relation to the transaction value, dispersion of capital of the acquiring company, audit firm size, and participation of the acquiring company in American Depositary Receipts (ADRs) programs. The control variables used were listing of the acquiring company in the various segments of BM&FBOVESPA, operation sector, origin (state, private company with national capital or private company with foreign capital), and relative acquired company size in relation to the acquiring company. We analyzed business combination transactions that took place in 2010, reported by 40 open capital companies involved in 76 transactions. We conclude that the audit firm size and the relative acquired company size were factors that influenced on the level of disclosure of information regarding business combinations in 2010. The other factors showed no conclusive results

Nitration of the Pollen Allergen Bet v 1.0101 Enhances the Presentation of Bet v 1-Derived Peptides by HLA-DR on Human Dendritic Cells

Nitration of pollen derived allergens can occur by NO2 and ozone in polluted air and it has already been shown that nitrated major birch (Betula verrucosa) pollen allergen Bet v 1.0101 (Bet v 1) exhibits an increased potency to trigger an immune response. However, the mechanisms by which nitration might contribute to the induction of allergy are still unknown. In this study, we assessed the effect of chemically induced nitration of Bet v 1 on the generation of HLA-DR associated peptides. Human dendritic cells were loaded with unmodified Bet v 1 or nitrated Bet v 1, and the naturally processed HLA-DR associated peptides were subsequently identified by liquid chromatography-mass spectrometry. Nitration of Bet v 1 resulted in enhanced presentation of allergen-derived HLA-DR-associated peptides. Both the copy number of Bet v 1 derived peptides as well as the number of nested clusters was increased. Our study shows that nitration of Bet v 1 alters antigen processing and presentation via HLA-DR, by enhancing both the quality and the quantity of the Bet v 1-specific peptide repertoire. These findings indicate that air pollution can contribute to allergic diseases and might also shed light on the analogous events concerning the nitration of self-proteins