Characteristics of Entrained Air Voids in Hardened Concrete with the Method of Digital Image Analysis Coupled with Schwartz-Saltykov Conversion

This paper presents the characteristics of air void systems in hardened concrete with the method of digital image analysis (DIA) coupled with Schwartz-Saltykov (SS) conversion. The results indicate that the DIA method coupled with SS conversion estimates the air content with more accuracy than it would without SS conversion; the correlation between air content obtained from the DIA method, and that from the thin section (TS) method is as good as the correlation observed between the pressure saturation (PS) method and the TS method. It was also found that the DIA method shows a better correlation with the TS method when the spacing factor without SS conversion is considered, while both methods show poor correlations when the corresponding specific surface is considered. In addition, it indicates that the peak of three-dimensional size distribution (3-DSD) of air voids after SS conversion falls in smaller voids, and 3-DSD of air voids shifts to a narrow size range, in comparison with the 2-DSD without SS conversion; the shape of the 3-DSD air voids remains constant irrespective of the class widths. Increasing the number of classes can minimise the standard deviation in the estimation, however, it also results in a leap in voids volume density, which will influence the estimation of air content.     

Role of Chemistry and Crystal Structure on the Electronic Defect States in Cs-Based Halide Perovskites

The electronic structure of a series perovskites ABX₃ (A = Cs; B = Ca, Sr, and Ba; X = F, Cl, Br, and I) in the presence and absence of antisite defect X_B were systematically investigated based on density-functional-theory calculations. Both cubic and orthorhombic perovskites were considered. It was observed that for certain perovskite compositions and crystal structure, presence of antisite point defect leads to the formation of electronic defect state(s) within the band gap. We showed that both the type of electronic defect states and their individual energy level location within the bandgap can be predicted based on easily available intrinsic properties of the constituent elements, such as the bond-dissociation energy of the B–X and X–X bond, the X–X covalent bond length, and the atomic size of halide (X) as well as structural characteristic such as B–X–B bond angle. Overall, this work provides a science-based generic principle to design the electronic states within the band structure in Cs-based perovskites in presence of point defects such as antisite defect.     

Survival of patients receiving fibrinolytic therapy for acute ST-segment elevation myocardial infarction in a developing country – patient characteristics and predictors of mortality

There is paucity of outcomes data on patients receiving fibrinolytic therapy (FT) for acute ST-elevation myocardial infarction (STEMI) in Indo-Asians. We conducted this study to determine survival as well as correlates of mortality in this population. Hospital charts of 230 patients receiving FT for acute STEMI between January 2002 and December 2004 were reviewed. Primary outcome variable was total mortality. Cox proportional hazards regression models were constructed. At a median follow-up of 717 days, 13.5% died, majority (23) during the in-hospital period. Multivariate predictors of mortality included (adjusted hazards ratio [HR], 95% confidence interval [CI]) age (HR 1.06, 95% CI 1.01–1.13), ejection fraction (HR 0.93, 95% CI 0.89–0.97), admission white cell count (HR 1.02, 95% CI 1.01–1.04) and change in ST-segment elevation (HR 0.96, 95% CI 0.92–0.99). We conclude that patients receiving FT for acute STEMI in Pakistan are a relatively high-risk group with a 10% in-hospital mortality and high frequency of recurrent events. Comparison data with primary angioplasty as an alternative strategy are needed.     

Impact of Microvascular Obstruction on the Assessment of Coronary Flow Reserve,Index of Microcirculatory Resistance,and Fractional Flow Reserve After ST-Segment Elevation Myocardial Infarction

Background

Invasive assessment of coronary physiology (IACP) offers important prognostic insights in ST-segment elevation myocardial infarction (STEMI) but the dynamics of coronary recovery are poorly understood.

Objectives

This study sought to examine the evolution of coronary flow reserve (CFR), index of microcirculatory resistance (IMR), ratio of distal coronary pressure (Pd) to mean aortic pressure (Pa), and fractional flow reserve (FFR) in patients undergoing primary percutaneous coronary intervention (PPCI).

Methods

82 patients with STEMI underwent IACP at PPCI. Repeat IACP was performed in 61 patients (74%) at day 1 and in 46 patients (56%) at 6 months. Contrast-enhanced cardiac magnetic resonance imaging (CMR) was performed in 45 patients (55%) at day 1 and in 41 patients (50%) at 6 months. Changes in IACP were compared between patients with and without microvascular obstruction (MVO) on CMR.

Results

MVO was present in 21 of 45 patients (47%). Patients with MVO had lower CFR at PPCI and day 1 (p < 0.05) and a trend toward higher IMR values (p = 0.07). At 6 months, CFR and IMR were not significantly different between the groups. Baseline flow and Pd/Pa remained stable over time but FFR reduced significantly between PPCI and 6 months (p = 0.008); this reduction was mainly observed in patients with MVO (p = 0.006) but not in those without MVO (p = 0.21).

Conclusions

In PPCI-treated patients with STEMI, coronary microcirculation begins to recover within 24 h and recovery progresses further by 6 months. FFR significantly reduces from baseline to 6 months. The presence of MVO indicates a highly dysfunctional microcirculation.     

Regulation of iron homeostasis through the erythroferrone-hepcidin axis in sickle cell disease

Sickle cell disease (SCD) has a distinct pattern of transfusional iron overload (IO) when compared to transfusion-dependent β-thalassaemia major (TDT). We conducted a single institution prospective study to evaluate plasma biomarkers of iron regulation and inflammation in patients with SCD with IO (SCD IO cases, n = 22) and without IO (SCD non-IO cases, n = 11), and non-SCD controls (n = 13). Hepcidin was found to be inappropriately low, as evidenced by a significantly higher median hepcidin/ferritin ratio in non-SCD controls compared to SCD IO cases (0·3 vs. 0·02, P < 0·0001) and SCD non-IO cases (0·3 vs. 0·02, P < 0·0001), suggesting that certain inhibitory mechanism (s) work to suppress hepcidin in SCD. As opposed to the SCD non-IO state, where hepcidin shows a strong significant positive correlation with ferritin (Spearman ρ = 0·7, P = 0·02), this correlation was lost when IO occurs (Spearman ρ = −0·2, P = 0·4). Although a direct non-linear correlation between erythroferrone (ERFE) and hepcidin did not reach statistical significance both in the IO (Spearman ρ = −0·4, P = 0·08) and non-IO state (Spearman ρ = −0·6, P = 0·07), patients with highest ERFE had low hepcidin levels, suggesting that ERFE contributes to hepcidin regulation in some patients. Our results suggest a multifactorial mechanism of hepcidin regulation in SCD.     

‘The clock keeps ticking’ – the role of a community-based intervention in reducing delays in seeking emergency obstetric care in rural Bangladesh: a quasi-experimental study

Objective

To explore the role of a community-based intervention in reducing delays in accessing emergency obstetric care (EmOC) in rural Bangladesh, and the factors associated with delayed decision making, reaching the health facility and receiving treatment.

Study design

Quasi-experimental study.

Methods

Multistage random sampling was used to select 540 villages, from which 1200 women who reported obstetric complications in March–April 2010 were interviewed.

Results

The median time taken to make the decision to access health care was significantly lower in the intervention areas compared with the control areas (80 vs 90 min). In addition, the median time taken to reach the health facility was significantly lower in the intervention areas compared with the control areas (110 vs 135 min). However, no difference was found in the median time taken to receive treatment. Multiple linear regressions demonstrated that the community intervention significantly reduced decision making and time taken to reach the health facility when accessing EmOC in rural Bangladesh. However, for women experiencing haemorrhage, the delays were longer in the intervention areas. Protective factors against delayed decision making included access to television, previous medical exposure, knowledge, life-threatening complications during childbirth and use of a primary health facility. Financial constraints and traditional perceptions were associated with delayed decision making. Complications during labour, use of a motorized vehicle and use of a primary health facility were associated with faster access to EmOC, and poverty, distance, transportation difficulties and decision made by male guardian were associated with slower access to EmOC.

Conclusions

The intervention appeared to reduce the time taken to make the decision to access health care and the time taken to reach the health facility when accessing EmOC. This study provides support for a focus on emergency preparedness for timely referral from the community.     

Primary intra osseous venous malformation of nasal bone: A rare case report

Primary intra osseous venous malformation with involvement of nasal bone is a rare phenomenon. Nasal bone intraosseous venous malformation on a back ground of port wine stain of face has not been reported in the available literature. We report the very rare case of intraosseous venous malformation of left nasal bone developing on a background of port wine stain of face, its diagnosis, pathology, management and review of literature.KEY WORDS: Intraosseous venous malformation, nasal bone, port wine stain, sun burst appearance