Thermal conductivity of polymer nanocomposites made with carbon nanofibers

An internal mixer was used to prepare polycarbonate (PC)-based nanocomposites containing carbon fibers, carbon nanofibers (CNF), and mixtures of the two fillers. The influence of the filler volume fraction, the relative amounts of the two fillers, and the filler orientation relative to the direction of heat flow on the thermal conductivity was examined. Filler orientation was obtained by the extrusion of strands of the nanocomposite. The thermal conductivity was measured using a steady-state heat conduction technique. The CNF were fragile, and their aspect ratio could be decreased during processing. In general, the composite thermal conductivity increased with increasing filler content. Fiber alignment in the heat flux direction resulted in a significant increase in thermal conductivity. Mixing of nanofibers with microfibers resulted contacts between the microfibers. This, together with fiber alignment provided large increases in the thermal conductivity

Rheological and mechanical properties of ABS/PC blends

Acrylonitrile-Butadiene-Styrene (ABS), polycarbonate (PC) and their alloys are an important class of engineering thermoplastics that are widely used for automotive industry, computer and equipment housings. For the process of recycling mixtures of ABS and PC, it is desirable to know how sensitive the blend properties are to changes in compositions. It was for this reason that blends of virgin ABS and virgin PC at five different compositions, namely, 15%, 30%, 50%, 70% and 85% by weight of ABS were prepared and characterised by rheological and mechanical measurements. Rheological properties of these blends in steady, oscillatory and transient step shear and mechanical properties, namely, tensile strength, elongation-at-break and Izod impact strength are reported. The results show that PC behaves in a relatively Newtonian manner, but ABS exhibits significant shear thinning. The ABS-rich blends show a trend that is similar to that of ABS, while PC-rich blends, namely 0% and 15%, exhibit a nearly Newtonian behaviour. However, at a fixed shear rate or frequency, the steady shear or the dynamic viscosity varied respectively in a non-monotonic manner with composition. Except for 15% blend, the viscosities of other blends fall into a narrow band indicating a wide-operation window of varying blend ratio. The blends exhibited a lower viscosity than either of the two pure components. The other noticeable feature was that the blends at 70% and 85% ABS content had a higher G' than pure ABS, indicating an enhancement of elastic effect. The tensile yield strength of the blends followed the ‘rule of mixtures’ showing a decreasing value with the increase of ABS content in PC. However, the elongation-at-break and the impact strength did not appear to obey this ‘rule of mixtures,’ which suggests that morphology of the blends also plays a significant role in determining the properties. Indeed, scanning electron micrographs of the fracture surfaces of the different blends validate this hypothesis, and the 15% blend is seen to have the most distinct morphology and correspondingly different behaviour and properties

Flammability properties of virgin and recycled Polycarbonate (PC) and Acrylonitrile-Butadiene-Styrene (ABS) recovered from end-of-life electronics

Acrylonitrile-Butadiene-Styrene (ABS), Polycarbonate (PC) and their alloys are widely used in automotive industry, computer and equipment housings. With increasing disposal of end-of-life electronic equipment, there is also an increased demand for recycling of these materials so that they do not pose environmental challenge as solid waste. One of the recycling approaches is mechanical recycling of these thermoplastics where recycled plastic is melt blended with virgin materials to obtain a high quality product. Besides obtaining desirable mechanical properties, such blends should also conform to fire safety standards. In this work, a series of blends were prepared using PC and ABS recovered from discarded computers and virgin materials using a twin-screw extruder. Their flammability properties were evaluated using burner flammability tests and Ohio State University (OSU) release rate tests. It was found that the extinguishing time, burning extent and weight loss appears to progressively decrease with the addition of both virgin or recycled PC to virgin or recycled ABS. It was also seen that the addition of the 70% of PC, virgin or recycled, to ABS virgin or recycled, appears to significantly decrease heat release and smoke evolution. The results of this study indicate that recycled polycarbonate can be used as an additive for virgin or recycled ABS, as a means of giving flame resistance to ABS in high-value applications. This result is significant when related to the result obtained by a separate study indicating that up to 25% of recycled material can be used without degradation of mechanical properties in the presence of 15% short glass fiber reinforcement

Could Peer-Mentors Support Families of Care Home Residents to Prepare for Deterioration and End-of-Life? An Interview Study with Families and Care Home Staff

When older people move into a care home, family members often continue to be involved in caregiving. This can include contributing to discussion and decisions about care and treatment, especially when the resident lacks capacity. However, families may not know what to expect as their relative's condition progresses and may not have a good understanding of their relative's end-of-life care and treatment wishes. Therefore, although often willing, families may feel unprepared for making decisions in advance of or at the time of deterioration and end-of-life. The study aimed to explore the potential role that peer-mentors might have in supporting families to prepare for discussion and decisions about care and treatment and to understand what participants would consider to be important characteristics of an effective peer-mentor and peer-mentoring program. The study was guided by the philosophical assumptions of social constructionism. Data from semistructured interviews with 14 current and 15 bereaved family members and 11 senior members of care were analysed thematically. Findings suggest that peer-mentors could help to empower families to prepare to be involved in discussions and decisions about the types of care their relatives might receive as their health deteriorates and they reach the end-of-life. However, it was seen as important that peer-mentors have lived experience of supporting a relative in a care home, strong interpersonal and communication skills, and the ability to discuss deterioration and end-of-life in a compassionate but factual manner. Although peer-mentoring is often time-limited, introducing mentors to families earlier in the care journey, for example, before admission into a care home, could enable a trusting relationship to develop. This, in turn, could facilitate open discussions about what to expect and different care choices as the person's health changes.</p

Cardiorespiratory Responses between One-Legged and Two-Legged Cycling in Patients with Idiopathic Pulmonary Fibrosis.

International guidelines recommend exercise training within pulmonary rehabilitation (PR) for adults with idiopathic pulmonary fibrosis (IPF) [1]. However, the magnitude of benefits of PR in IPF may be less than in COPD [2] and are not sustained [3]. Partitioned muscle training has been investigated for other chronic diseases where a central limitation to exercise dominates [4-6]. One-legged cycling partitions the targeted exercising muscle thereby reducing the total ventilatory burden for the same muscle specific power. In ventilatory limited patients with COPD, partitioned training increases cardiorespiratory fitness [4, 7] measured by peak oxygen uptake (V̇ O2pk) greater than that achieved with conventional twolegged cycle training. We hypothesised that patients with IPF would increase their tolerable exercise time of a leg exercising alone (one-legged cycling) compared to two-legged cycling so that the total work would be doubled (the primary outcome). We also aimed to quantify peripheral muscle aerobic capacity relative to the central capacity by determining the ratio of V̇ O2pk achieved during one- versus two-legged cycling

Time-in-range and frequency of continuous glucose monitoring: Recommendations for South Asia

Background and aim: The prevalence of diabetes is on its rise and South Asia bears a huge burden. Several factors such as heterogeneity in genetics, socio-economic factors, diet, and sedentary behavior contribute to the heightened risk of developing diabetes, its rapid progression, and the development of complications in this region. Even though there have been considerable advances in glucose monitoring technologies, diabetes treatments and therapeutics, glycemic control in South Asia remains suboptimal. The successful implementation of treatment interventions and metrics for the attainment of glycemic goals depends on appropriate guidelines that accord with the characteristics of the diabetes population. Method: The data were collected from studies published for more than the last ten years in the electronic databases PubMed and Google Scholar on the various challenges in the assessment and achievement of recommended TIR targets in the SA population using the keywords: Blood glucose, TIR, TAR, TBR, HbA1c, hypoglycemia, CGM, Gestational diabetes mellitus (GDM), and diabetes. Results: The objective of this recommendation is to discuss the limitations in considering the IC-TIR Expert panel recommendations targets and to propose some modifications in the lower limit of TIR in older/high-risk population, upper limit of TAR, and flexibility in the percentage of time spent in TAR for pregnant women (GDM, T2DM) for the South Asian population. Conclusion: The review sheds insights into some of the major concerns in implementing the IC-TIR recommendations in South Asian population where the prevalence of diabetes and its complications are significantly higher and modifications to the existing guidelines for use in routine clinical practice

Post-monsoon air quality degradation across Northern India: assessing the impact of policy-related shifts in timing and amount of crop residue burnt

The past decade has seen episodes of increasingly severe air pollution across much of the highly populated Indo-Gangetic Plain (IGP), particularly during the post-monsoon season when crop residue burning (CRB) is most prevalent. Recent studies have suggested that a major, possibly dominant contributor to this air quality decline is that northwest (NW) Indian rice residue burning has shifted later into the post-monsoon season, as an unintended consequence of a 2009 groundwater preservation policy that delayed the sowing of irrigated rice paddy. Here we combine air quality modelling of fine particulate matter (PM2.5) over IGP cities, with meteorology, fire and smoke emissions data to directly test this hypothesis. Our analysis of satellite-derived agricultural fires shows that an approximate 10 d shift in the timing of NW India post-monsoon residue burning occurred since the introduction of the 2009 groundwater preservation policy. For the air quality crisis of 2016, we found that NW Indian CRB timing shifts made a small contribution to worsening air quality (3% over Delhi) during the post-monsoon season. However, if the same agricultural fires were further delayed, air quality in the CRB source region (i.e. Ludhiana) and for Delhi could have deteriorated by 30% and 4.4%, respectively. Simulations for other years highlight strong inter-annual variabilities in the impact of these timing shifts, with the magnitude and even direction of PM2.5 concentration changes strongly dependent on specific meteorological conditions. Overall we find post-monsoon IGP air quality to be far more sensitive to meteorology and the amount of residue burned in the fields of NW India than to the timing shifts in residue burning. Our study calls for immediate actions to provide farmers affordable and sustainable alternatives to residue burning to hasten its effective prohibition, which is paramount to reducing the intensity of post-monsoon IGP air pollution episodes

Prothrombin complex concentrate in cardiac surgery: A systematic review and meta-analysis.

BACKGROUND: Prothrombin complex concentrate (PCC) has recently emerged as effective alternative to fresh frozen plasma (FFP) in treating excessive perioperative bleeding. We performed a systematic review and meta-analysis to evaluate the safety and efficacy of PCC administration as first-line treatment for coagulopathy following adult cardiac surgery. METHODS: We searched PubMed/MEDLINE, EMBASE, and the Cochrane Library from inception to the end of March 2018 to identify eligible articles. Adult patients undergoing cardiac surgery and receiving perioperative PCC were compared to those receiving FFP. RESULTS: A total of 861 adult patients from 4 studies were retrieved. No randomized studies were identified. Pooled odds ratio (OR) showed that PCC cohort was associated with a significant reduction in the risk of RBC transfusion (OR: 2.22; 95% confidence interval [CI] 1.45-3.40) and units of RBC received (OR: 1.34; 95%CI: 0.78-1.90). No differences were observed between the groups for re-exploration for bleeding (OR: 1.09; 95%CI: 0.66-1.82), chest drain output at 24 hours (OR: 66.36; 95%CI: -82.40-216.11), hospital mortality (OR: 0.94; 95%CI: 0.59-1.49), stroke (OR: 0.80; 95%CI: 0.41-1.56), and occurrence of acute kidney injury (OR: 0.80; 95%CI: 0.58-1.12). A trend toward increased risk of renal replacement therapy was observed in the PCC group (OR: 0.41; 95%CI: 0.16-1.02). CONCLUSIONS: In patients with significant bleeding following cardiac surgery, PCC administration seems to be more effective than FFP in reducing perioperative blood transfusions. No additional risks of thromboembolic events or other adverse reactions were observed. Randomized controlled trials are needed to definitively establish the safety of PCC in cardiac surgery

Effects of haemodynamically atrio-ventricular optimized His bundle pacing on heart failure symptoms and exercise capacity: the His Optimized Pacing Evaluated for Heart Failure (HOPE-HF) randomized, double-blind, cross-over trial

Aims: Excessive prolongation of PR interval impairs coupling of atrio-ventricular (AV) contraction, which reduces left ventricular pre-load and stroke volume, and worsens symptoms. His bundle pacing allows AV delay shortening while maintaining normal ventricular activation. HOPE-HF evaluated whether AV optimized His pacing is preferable to no-pacing, in a double-blind cross-over fashion, in patients with heart failure, left ventricular ejection fraction (LVEF) ≤40%, PR interval ≥200 ms and either QRS ≤140 ms or right bundle branch block. Methods and results: Patients had atrial and His bundle leads implanted (and an implantable cardioverter-defibrillator lead if clinically indicated) and were randomized to 6 months of pacing and 6 months of no-pacing utilizing a cross-over design. The primary outcome was peak oxygen uptake during symptom-limited exercise. Quality of life, LVEF and patients' holistic symptomatic preference between arms were secondary outcomes. Overall, 167 patients were randomized: 90% men, 69 ± 10 years, QRS duration 124 ± 26 ms, PR interval 249 ± 59 ms, LVEF 33 ± 9%. Neither peak oxygen uptake (+0.25 ml/kg/min, 95% confidence interval [CI] −0.23 to +0.73, p = 0.3) nor LVEF (+0.5%, 95% CI −0.7 to 1.6, p = 0.4) changed with pacing but Minnesota Living with Heart Failure quality of life improved significantly (−3.7, 95% CI −7.1 to −0.3, p = 0.03). Seventy-six percent of patients preferred His bundle pacing-on and 24% pacing-off (p < 0.0001). Conclusion: His bundle pacing did not increase peak oxygen uptake but, under double-blind conditions, significantly improved quality of life and was symptomatically preferred by the clear majority of patients. Ventricular pacing delivered via the His bundle did not adversely impact ventricular function during the 6 months