STEM electron beam-induced current measurements of organic-inorganic perovskite solar cells.

We describe a new approach for preparing organic-inorganic perovskite solar cells for electron beam-induced current (EBIC) measurements in plan-view geometry. This method substantially reduces sample preparation artefacts, provides good electrical contact and keeps the preparation steps as close as possible to those for real devices. Our EBIC images were acquired simultaneously with annular dark-field scanning transmission electron microscopy images using a home-made highly sensitive EBIC amplifier. High-angle annular dark-field images and energy dispersive X-ray maps were recorded from the same area immediately afterwards. This allowed the EBIC contrast to be correlated with regions containing N and a deficiency of O. The EBIC contrast was also found to be similar to secondary electron contrast recorded with a scanning electron microscope. By identifying the generation and absorption electron processes, we determine that EBIC cannot be separated from the secondary electron and absorbed currents. This means that careful analysis needs to be performed before conclusions can be made on the origin of the current measured across p-n or p-i-n junctions.

Synthesis of ligand-free CZTS nanoparticles via a facile hot injection route.

Single-phase, ligand-free Cu2ZnSnS4 (CZTS) nanoparticles that can be dispersed in polar solvents are desirable for thin film solar cell fabrication, since water can be used as the solvent for the nanoparticle ink. In this work, ligand-free nanoparticles were synthesized using a simple hot injection method and the precursor concentration in the reaction medium was tuned to control the final product. The as-synthesized nanoparticles were characterized using various techniques, and were found to have a near-stoichiometric composition and a phase-pure kesterite crystal structure. No secondary phases were detected with Raman spectroscopy or scanning transmission electron microscopy energy dispersive x-ray spectroscopy. Furthermore, high resolution transmission electron microscopy showed large-sized nanoparticles with an average diameter of 23 nm ± 11 nm. This approach avoids all organic materials and toxic solvents that otherwise could hinder grain growth and limit the deposition techniques. In addition the synthesis route presented here results in nanoparticles of a large size compared to other ligand-free CZTS nanoparticles, due to the high boiling point of the solvents selected. Large particle size in CZTS nanoparticle solar cells may lead to a promising device performance. The results obtained demonstrate the suitability of the synthesized nanoparticles for application in low cost thin film solar cells.

The CEPHEUS Pan-Asian survey: high low-density lipoprotein cholesterol goal attainment rate among hypercholesterolaemic patients undergoing lipid-lowering treatment in a Hong Kong regional centre.

OBJECTIVES. To evaluate attainment of low-density lipoprotein cholesterol goals among hypercholesterolaemic patients undergoing lipid-lowering drug treatment in Hong Kong and to identify potential determinants of treatment outcomes. DESIGN. Cross-sectional observational study. SETTING. A single site in Hong Kong, as part of the CEPHEUS Pan-Asian survey. PATIENTS. Subjects with hypercholesterolaemia aged 18 years or above, who had been on lipid-lowering drug treatment for at least 3 months with no dose adjustment for at least 6 weeks. RESULTS. A total of 561 such patients (mean age, 65.3; standard deviation, 9.7 years) were evaluated. Most had major cardiovascular risk factors; 534 (95.2%) of 561 patients had coronary heart disease and 534 (95.4%) of 560 patients had low-density lipoprotein cholesterol goals set at lower than 70 mg/dL. In all, 465 (82.9%) patients attained their respective low-density lipoprotein cholesterol goals. Among 75 patients who had coronary heart disease or equivalent risk, and multiple risk factors with a 10-year coronary heart disease risk of over 20%, 62 (82.7%) attained their respective low-density lipoprotein cholesterol goals. Significant predictors of low-density lipoprotein cholesterol goal attainment included the patient's baseline lipid profile (total cholesterol and low-density lipoprotein cholesterol levels), blood pressure, and drugs (statin/non-statin) used for treatment. CONCLUSIONS. Hypercholesterolaemic patients undergoing lipid-lowering drug treatment in the present Hong Kong study were able to achieve a very high attainment rate for the low-density lipoprotein cholesterol goal, despite the fact that most of them had major cardiovascular risk factors.

HPV vaccination in Hong Kong: implications for medical education.

OBJECTIVE: To explore the experience and attitudes of physicians in clinics, and to facilitate physicians' promotion of HPV vaccination. DATA SOURCES: Primary data collected from conducting semi-structural in-depth interviews from May to June 2010 with 12 physicians in one district in Hong Kong to understand their experience of providing HPV vaccines, the difficulties in promoting HPV vaccines, and their attitudes towards HPV vaccination. STUDY DESIGN: Physicians identified 4 categories of factors related to their experiences of and attitudes to providing HPV vaccination: (a) background information on HPV vaccination provided by physicians, (b) factors influencing women to receive vaccination, (c) physicians' recommendations to the public on HPV vaccines, and (d) physicians' perspectives on HPV vaccine promotion. CONCLUSIONS: Our findings show that public knowledge on HPV and cervical cancer is insufficient and the role of government in vaccine promotion is unclear. Promotion strategies such as physicians' recommendation, financial assistance and health education provided by the government will influence HPV vaccination and its promotion.

Does measurement of the anatomic axis consistently predict hip-knee-ankle angle (HKA) for knee alignment studies in osteoarthritis? Analysis of long limb radiographs from the multicenter osteoarthritis (MOST) study.

OBJECTIVE: Researchers commonly use the femoral shaft-tibial shaft angle (FS-TS) from knee radiographs to estimate the hip-knee-ankle angle (HKA) in studies examining risk factors for knee osteoarthritis (OA) incidence and progression. The objective of this study was to determine the relationship between HKA and FS-TS, depending on the method of calculating FS-TS and the direction and degree of knee deformity. METHODS: 120 full-length digital radiographs were assigned, with 30 in each of four alignment groups (0.0°-4.9°, and ≥5.0° of varus and valgus), from a large cohort of persons with and at risk of knee OA. HKA and five measures of FS-TS (using progressively shorter shaft lengths) were obtained using Horizons Analysis Software, Orthopaedic Alignment & Imaging Systems Inc. (OAISYS). The offsets between HKA and the different versions of FS-TS were calculated, with 95% confidence intervals (CIs). Pearson correlations were calculated. RESULTS: In varus limbs use of a shorter shaft length increased the offset between HKA and FS-TS from 5.1° to 7.0°. The opposite occurred with valgus limbs (from 5.0° to 3.7°). Correlations between HKA and FS-TS for the whole sample of 120 individuals were excellent (r range 1.00-0.88). However, correlations for individual alignment groups were low to moderate, especially for the shortest-shaft FS-TS (r range 0.41-0.66). CONCLUSIONS: The offsets obtained using the shorter FS-TS measurements vary depending on direction and degree of knee deformity, and therefore may not provide reliable predictions for HKA We recommend that full-length radiographs be used whenever an accurate estimation of HKA is required, although broad categories of alignment can be estimated with FS-TS.

Systematic identification of placental epigenetic signatures for the noninvasive prenatal detection of Edwards syndrome.

BACKGROUND: Noninvasive prenatal diagnosis of fetal aneuploidy by maternal plasma analysis is challenging owing to the low fractional and absolute concentrations of fetal DNA in maternal plasma. Previously, we demonstrated for the first time that fetal DNA in maternal plasma could be specifically targeted by epigenetic (DNA methylation) signatures in the placenta. By comparing one such methylated fetal epigenetic marker located on chromosome 21 with another fetal genetic marker located on a reference chromosome in maternal plasma, we could infer the relative dosage of fetal chromosome 21 and noninvasively detect fetal trisomy 21. Here we apply this epigenetic-genetic (EGG) chromosome dosage approach to detect Edwards syndrome (trisomy 18) in the fetus noninvasively. PRINCIPAL FINDINGS: We have systematically identified methylated fetal epigenetic markers on chromosome 18 by methylated DNA immunoprecipitation (MeDIP) and tiling array analysis with confirmation using quantitative DNA methylation assays. Methylated DNA sequences from an intergenic region between the VAPA and APCDD1 genes (the VAPA-APCDD1 DNA) were detected in pre-delivery, but not post-delivery, maternal plasma samples. The concentrations correlated positively with those of an established fetal genetic marker, ZFY, in pre-delivery maternal plasma. The ratios of methylated VAPA-APCDD1(chr18) to ZFY(chrY) were higher in maternal plasma samples of 9 male trisomy 18 fetuses than those of 27 male euploid fetuses (Mann-Whitney test, P=0.029). We defined the cutoff value for detecting trisomy 18 fetuses as mean+1.96 SD of the EGG ratios of the euploid cases. Eight of 9 trisomy 18 and 1 of 27 euploid cases showed EGG ratios higher than the cutoff value, giving a sensitivity of 88.9% and a specificity of 96.3%. CONCLUSIONS: Our data have shown that the methylated VAPA-APCDD1 DNA in maternal plasma is predominantly derived from the fetus. We have demonstrated that this novel fetal epigenetic marker in maternal plasma is useful for the noninvasive detection of fetal trisomy 18.

Isolated left ventricular non-compaction: an unusual indication for heart transplantation.

We report a patient with isolated left ventricular non-compaction diagnosed by echocardiography and cardiac magnetic resonance imaging. She developed refractory congestive heart failure and subsequently underwent successful heart transplantation. This type of cardiomyopathy is thought to be caused by the arrest of normal embryogenesis of the endocardium and myocardium. The spectrum of clinical, radiological, and pathological abnormalities is discussed.

Reliability of ventilatory parameters during cycle ergometry in multicentre trials in COPD.

We studied the distribution profiles and repeatability of key exercise performance parameters in the first large multicentre trials to include these measurements in chronic obstructive pulmonary disease (COPD). After a screening visit, 463 subjects with COPD (mean+/-SD forced expiratory volume in 1 s 43+/-13% predicted) completed two run-in visits before treatment randomisation. At the run-in visits, measurements were conducted at rest, at a standardised time near end-exercise (isotime) and at peak exercise during constant work rate (CWR) cycle tests at 75% of each individual's maximum work capacity. The intraclass correlation coefficient was used to evaluate the test-retest repeatability of measurements of endurance time (ET), inspiratory capacity (IC), ventilation and dyspnoea intensity (Borg scale) during exercise. IC, ventilation and dyspnoea ratings were normally distributed; ET showed rightward skew (median or = 0.87). Ventilation was repeatable over the same time-points (R > or = 0.92), as was dyspnoea intensity at isotime (R = 0.79) and at peak exercise (R = 0.81). In conclusion, key perceptual and ventilatory parameters can be reliably measured during CWR cycle exercise in multicentre clinical trials in moderate to very severe COPD.

Evaluation of acute bronchodilator reversibility in patients with symptoms of GOLD stage I COPD.

BACKGROUND: Patients with symptoms of GOLD stage I chronic obstructive pulmonary disease (COPD) can have significant abnormalities of ventilatory mechanics with greater exertional symptoms and exercise limitation than age-matched healthy subjects. In such patients the impact of bronchodilator therapy remains unknown and is difficult to evaluate. METHODS: The acute effects of nebulised ipratropium bromide 500 microg (IB) on resting pulmonary function and on dyspnoea and ventilatory parameters during symptom-limited constant work rate cycle exercise were measured. In a randomised double-blind crossover study, 16 patients with COPD (mean (SD) post-bronchodilator forced expiratory volume in 1 s (FEV(1)) 90 (7)% predicted, FEV(1)/forced vital capacity (FVC) 59 (7)%) with a significant smoking history (mean (SD) 44 (16) pack-years) inhaled either IB or placebo on each of two separate visits. Pulmonary function tests and cycle exercise at 80-85% of each subject's maximal work capacity were performed 2 h after dosing. RESULTS: Compared with placebo, FEV(1) increased 5 (9)% predicted, residual volume decreased 12 (20)% predicted and specific airway resistance decreased 81 (93)% predicted (all p<0.05) after IB. At a standardised time during exercise, dynamic inspiratory capacity and tidal volume significantly increased in tandem by 0.12 and 0.16 litres, respectively (each p<0.05), dyspnoea fell by 0.9 (1.8) Borg units (p = 0.07) and dyspnoea/ventilation ratios fell significantly (p<0.05). The fall in dyspnoea intensity at higher submaximal ventilations correlated with the concurrent decrease in end-expiratory lung volume (p<0.05). CONCLUSION: In patients with symptoms of GOLD stage I COPD, IB treatment is associated with modest but consistent improvements in airway function, operating lung volumes and dyspnoea intensity during exercise. These results provide a physiological rationale for a trial of bronchodilator therapy in selected patients with milder but symptomatic COPD.

Synthesis and characterization of CdSe nanorods using a novel microemulsion method at moderate temperature.

CdSe nanoparticles have been successfully synthesized using a novel microemulsion method at moderate temperature. It is found that with a combination of the surfactant AOT and hydrazine hydrate, it is possible to control the morphology of the nanoparticles. The hydrazine hydrate acts as both a reducing agent and a templating agent that favors the formation of a rodlike structure. The composition, morphology and optical properties of the CdSe nanoparticles were investigated using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption spectroscopy, photoluminescence (PL) spectroscopy, energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FT-IR) spectroscopy. The nucleation and growth mechanism for this system is also proposed based on a time-dependent study. This synthesis route provides a moderate temperature (100 degrees C) method for synthesizing rodlike CdSe, hence reducing the possibility of oxidation of this chalcogenide compound.

Bosentan use in systemic lupus erythematosus patients with pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) in patients with systemic lupus erythematosus (SLE) is uncommon but is associated with poor survival. This study aimed to examine the long-term effects of bosentan, a dual endothelin-1 receptor antagonist, on symptomatology, haemodynamics and quality of life measures in SLE patients with symptomatic PAH. Four local patients had been followed up prospectively with pre-defined protocol during 12-months of bosentan treatment. Six minute walk distance (6MWD), NYHA functional class, Borg Dyspnoea Index (BDI) and SF-36 were measured at 0, 3, 6, 9 and 12 months. Systolic pulmonary arterial pressure (PAP) was measured by transthoracic echocardiography at zero, six and 12 months. Clinical parameters were analysed, pooling data from other SLE patients reported in the literature (n = 4). Bosentan was found to result in significant improvement in 6MWD compared to baseline [+24.8 m, +26.2 m, +54 m and +62.7 m at three (P = 0.001), six (P = 0.001), nine (P = 0.24) and 12 (P = 0.01) months respectively]. A differential effect was found with greater response in patients with lower exercise capacity. This was accompanied by decrease in NYHA functional class, BDI, transient or sustained drop in systolic PAP and mild improvement in SF-36 domains including mental health, vitality, social function and general health. Significantly deranged liver function was found in one patient.

Controlled synthesis and association behavior of graft Pluronic in aqueous solutions.

Poly(vinyl pyrrolidone) (PVP) was grafted onto Pluronic F127 (PEO-PPO-PEO) to produce novel amphiphilic PVP-g-F127 graft copolymers. A controlled synthesis method was used to graft PVP onto different parts of F127. Two types of graft polymers were obtained: one has PVP grafted onto the PEO part of F127 and the other has PVP grafted onto the PPO part of F127. The association behavior of the two modified polymers was examined using differential scanning calorimetry, surface tension measurements, and dynamic light scattering.

A case of takotsubo cardiomyopathy: transient left ventricular apical ballooning.

A 78-year-old woman was admitted to hospital with central chest pain and the electrocardiographic and cardiac marker changes typical of acute anterior myocardial infarction. Coronary angiography revealed normal epicardial coronary arteries, and left ventriculography showed apical akinesis as well as basal hyperkinesis. This is a case of transient left ventricular apical ballooning or takotsubo cardiomyopathy, possibly attributable to catecholamine-mediated myocardial stunning.

Study of mixed micelles and interaction parameters for polymeric nonionic and normal surfactants.

Surface tension (ST) measurements were carried out on various binary mixtures of the "normal" surfactants, such as nonionic surfactant, hexaethylene glycol mono-n-dodecyl ether(C12EO6), and cationic surfactant, tetradecyltrimethylammonium bromide (TTAB), and polymeric copolymer, Pluronic F127, F127(PPO)-g-PVP, and F127(PEO)-g-PVP. In all cases mixed micellar aggregates were formed and critical micellar concentrations of binary mixtures containing different mole fractions of the surfactants were measured using surface tension measurement. In the region where mixed micelles are formed, the interaction of two "normal" surfactants and three "polymeric" nonionic surfactants showed synergistic behavior and the results were analyzed using a interaction parameter, beta, which characterized the interaction in the mixed micelle and introduced by a regular solution theory. The regular solution theory can be applied to describe the interaction between TTAB and C12EO6, and graft polymeric surfactants systems. The results discussed in this paper indicated that regular solution theory has broader extent of application.

Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)-g-poly(vinylpyrrolidone): association behavior in aqueous solution and interaction with anionic surfactants.

In this work, we aimed to study the association and interaction behavior of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) block copolymers grafted with poly(vinylpyrrolidone). Critical micellization concentrations were determined using fluorescent probes (pyrene) and critical micellization temperatures characterizing temperature-dependent transitions from monomers to multimolecular micelles were measured. The thermal responsiveness of the copolymer is not affected by the grafting. The hydrodynamic radius of the graft copolymer micelles is found to be greater than that of the original copolymer micelles. The graft copolymer is found to form anisotropic aggregates. The structure of the graft copolymer micelles is less disrupted by the anionic surfactant sodium dodecyl sulfate, compared to the ungraft copolymer.

Multiple brain abscesses in a patient with bilateral pulmonary arteriovenous malformations and immunoglobulin deficiency.

A 34 year old Chinese man presented with grand mal seizures complicating multiple brain abscesses caused by mixed oral flora. Because of persistent hypoxaemia contrast spiral thoracic computed tomography was done, which revealed bilateral pulmonary arteriovenous malformations (PAVMs). Concomitant IgA and IgG subclass deficiency was also found. The combination of these two conditions appears to have predisposed this patient to presumably paradoxical septic embolism. The patient's cerebral condition responded to postoperative antibiotic treatment and he eventually received selective coil embolisation of right lower lobe PAVMs, which relieved his hypoxaemia and dyspnoea.