High-yield synthesis of CsPbBr3nanoparticles: diphenylphosphine as a reducing agent and its effect in Pb-seeding nucleation and growth.

Based on the reported nucleation mechanisms for CsPbX3and II-VI/IV-VI quantum dots, CsPbBr3nanoparticles with a higher reaction-yield (up to 393% mass-increment) were synthetized by the hot-injection method. The introduction of diphenylphosphine (DPP) as a reducing agent improved nanoparticle nucleation and growth, giving out evidence for Pb-seeding in CsPbBr3nanoparticles formation. Additionally, a clear influence of the DPP in a CsPbBr3-Cs4PbBr6incomplete phase transformation was observed, marked by the appearance of several PbBr2nanoparticles. This indicated the need for an improved ratio between the stabilizing agents and the precursors, due to the increased number of nucleation sites produced by DPP. The resulting CsPbBr3nanoparticles showed high quality, as they displayed 70%-90% photoluminescence quantum yield; narrow size distribution with an average nanoparticle size of∼10 nm; and the characteristic cubic morphology reported in previous works. This increment in CsPbBr3nanoparticles' reaction yield will contribute to making them a more attractive option for different optoelectronic applications.

Study on photovoltaic stability and performance by incorporating tetrabutyl phosphonium iodide into the active layer of a perovskite type photovoltaic cell.

A simple synthesis of an ionic liquid is carried out using a trialkylphosphine and an alkyl halide. The results showed that the quality of perovskite crystals is enhanced by the incorporation of B4PI, when the percentage is 1.5% the PCE of champion PSCs MA98.5(B4PI)1.5PbI3 increases significantly from 15.5%, with a V OC of 0.957 mV, J SC of 23.6 mA cm-2, and an FF of 68.4%. Stability tests show that excess B4PI by 20% has a protective effect against humidity, MA80(B4PI)20PbI3 was more stable towards humidity, losing only 20% efficiency for 200 h.

Ultrasonic irradiation-assisted synthesis of Bi2S3 nanoparticles in aqueous ionic liquid at ambient condition.

In this work, an easy, fast and environmentally friendly method to obtain Bi2S3 nanostructures with sphere-like morphology is introduced. The promising material was successfully synthesized by a sonochemical route in 20% 1-ethyl-3-methylimidazolium ethyl sulfate [EMIM][EtSO4] ionic liquid solution (IL). Morphological studies by electron microscopy (SEM and TEM) show that the use of IL in the synthesis of Bi2S3 favors the formation of nanocrystals non-agglomerated. Micro Raman and energy dispersive X-ray spectroscopy (EDXS) were used to determine the composition and purity of the synthesized material. X-ray powder diffraction (XRD) and selective area electron diffraction (SAED) revealed that ultrasonic radiation accelerated the crystallization of Bi2S3 into orthorhombic bismuthinite structure. The band gap calculated from the diffuse reflectance spectra (DRS) was found to be 1.5eV.

Encapsulation and immobilization of papain in electrospun nanofibrous membranes of PVA cross-linked with glutaraldehyde vapor.

In this paper, papain enzyme (E.C. 3.4.22.2, 1.6 U/mg) was successfully immobilized in poly(vinyl alcohol) (PVA) nanofibers prepared by electrospinning. The morphology of the electrospun nanofibers was characterized by scanning electron microscopy (SEM) and the diameter distribution was in the range of 80 to 170 nm. The presence of the enzyme within the PVA nanofibers was confirmed by infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDXS) analyses. The maximum catalytic activity was reached when the enzyme loading was 13%. The immobilization of papain in the nanofiber membrane was achieved by chemical crosslinking with a glutaraldehyde vapor treatment (GAvt). The catalytic activity of the immobilized papain was 88% with respect to the free enzyme. The crosslinking time by GAvt to immobilize the enzyme onto the nanofiber mat was 24h, and the enzyme retained its catalytic activity after six cycles. The crosslinked samples maintained 40% of their initial activity after being stored for 14 days. PVA electrospun nanofibers are excellent matrices for the immobilization of enzymes due to their high surface area and their nanoporous structure.

Prevalence and characteristics of bone disease in cirrhotic patients under evaluation for liver transplantation.

BACKGROUND: We performed a retrospective study to examine the prevalence of bone disease (BD) among cirrhotic patients being evaluated for liver transplantation (OLT) using bone densitometry dual-energy x-ray absorptiometry in the hip/femoral neck and lumbar spine. The associations of BD with demographic and clinical data, disease etiology and liver function were studied by univariate and multivariate logistic regression analyses. Osteopenia and osteoporosis were defined by World Health Organization criteria. RESULTS: We included 486 patients (79% men of mean age, 53 ± 8.8 years (range, 21-69) who included 62.6% smoker and 23.7% diabetic subjects. Body mass index (BMI) was 28.8 ± 5.7 kg/m(2) (range, 16-43). The liver disease was Child-Pugh class A (22%), B (51%), or C (27%); the Model for End-Stage Liver Disease (MELD) score was 14.6 ± 5.4 (range, 7-33). The disease etiology was alcohol (59%), hepatitis C (32%), hepatitis B (10%), primary biliary cirrhosis (PBC) (2.3%), secondary biliary cirrhosis, (2%) or other causes (10%). In all, 350 patients (72%) had BD in the hip/femoral neck and/or lumbar spine: Global hip, 26% (osteopenia, 22%; osteoporosis, 4%); femoral neck, 48% (osteopenia, 43%; osteoporosis, 5%) and lumbar spine, 63% (osteopenia, 40%; osteoporosis, 23%). Univariate analysis showed the BD risk to increase with the following variables: Female gender (odds ratio [OR], 1.88; P = .023) and lower BMI (OR, 0.95; P = .012). Upon multivariate analysis, female gender (OR, 2.43; P = .004), lower BMI (OR, 0.96; P = .016), and tobacco use (OR, 1.59; P = .043) were significant. PBC showed BD in 100% of cases. By adjusting bone mineral density (BMD) values to age (Z-score) in relation to that defined by T-score, we observed a decrease in BD prevalence in both the femoral neck (20% vs 48%) and the lumbar spine (44% vs 63%). CONCLUSION: BD, especially in the lumbar spine, is common among cirrhotic patients under evaluation for OLT. Cirrhosis is a major BD risk factor that remains even when BMD values are adjusted for age. Female gender, lower BMI, and tobacco consumption are major risk factors for BD in cirrhotic patients. Bone densitometry must be included in the OLT evaluation of all patients.

Response to vaccination against hepatitis B virus with a schedule of four 40-µg doses in cirrhotic patients evaluated for liver transplantation: factors associated with a response.

We performed a retrospective study to evaluate the rate of and factors associated with a response to recombinant hepatitis B virus (HBV) vaccination using 4 intramuscular doses (40 µg) administered at 0, 1, 2, and 6 months among 278 cirrhotic patients being evaluated for orthotopic liver transplantation (OLT). We re-vaccinated 57 non-responders with the same schedule. The 39.2% overall response rate to vaccination included 36% after three and 40.7% after four doses, namely, a median anti-HBs level of 100 IU/mL (range, 10 to 1000 IU/mL). The 51% revaccination response rate achieved a median hepatitis B surface antibody (anti-HBs) level of 99 IU/mL (range, 11 to >1000 IU/mL). Upon univariate analysis, variables associated with a higher response were: better liver function (Child-Pugh class [A, 53.8% B, 33.3%, C, 30.1%; P = .002), Model for End-stage Liver-Disease (MELD) score (11.4 versus 13.6; P = .001]), absence of diabetes (43.6% versus 20.8%; P = .002), presence of isolated hepatitis B core antibody (anti-HBc) positivity (80% versus 37.7%; P = .007), and younger age (< 45 years, 52.2%; range, 45 to 55 years, 40.4%; > 55 years, 34.1%; P = .031). Upon multivariate logistic regression analysis, lower MELD score (odds ratio [OR]: 0.922; P = .046), absence of diabetes (OR:0.359; P = .008) and isolated anti-HBc positivity (OR:5.826; P = .034) were associated with a higher response. No differences were observed to be associated with gender, weight, body mass index, etiology or tobacco consumption. Among the same patient cohort (n = 79), the responses after the third and fourth doses were 36.7% and 51.9% respectively. In conclusion, the response rate to HBV vaccination in cirrhotic patients evaluated for OLT reached more than 35% among those who received at least 3 doses. It was higher among patients who showed isolated anti-HBc positivity, better liver function, younger age, and non-diabetic status. The fourth dose only increased the response rate by 24% over that obtained after the first three doses, whereas a revaccination achieved a 50% response rate, which probably accounts for revaccination after no response to 3 doses. Vaccination should be introduced against HBV in the early stages of the disease.

Prevalence of hepatitis B and A virus markers and vaccination indication in cirrhotic patients evaluated for liver transplantation in Spain.

In the absence of immunity, vaccination against hepatitis A virus (HAV) and hepatitis B virus (HBV) is recommended for patients with chronic liver disease and those evaluated for liver transplantation (OLT) HAV and HBV infections after OLT which are frequent in this setting, are associated with a worse prognosis. The aim of this study was to estimate the need for vaccination against HBV and HAV among cirrhotic patients who were candidates for OLT and associations with gender, age, and etiologic factors. HBV and HAV serological markers HBsAg, anti-HBc, antiHBs, immunoglobulin G (IgG)-anti-HAV were investigated among 568 patients, including 75% men. The overall mean age was 53.6 ± 8.9 years range 17-69, and 20% were diabetic. This etiologies were alcohol (68%), hepatitis C virus (35%) or other causes (10.4%). Child-Pugh classes were: A (26%), B (44%), and C (30%). In contrast with 359 patients (63.2%) who had negative HBV markers, 209 (36.8%) were positive: HBsAg (+), 43 (7.6%), isolated anti-HBc (+), 57 (10%), isolated anti-HBs (+), 19 (3.3%), anti-HBc (+)/anti-HBs (+), 90 (15.8%). HBV vaccine indication was performed in 416 patients (73.2%) who either had negative HBV markers or isolated anti-HBc (+). It was more frequently performed in women (82.3% versus 70.3%, P = .005), albeit with no differences according to age or etiology. There were only 8.2% (44/538) IgG-anti-HAV-negative, an indication for vaccination against HAV, which was more frequent affecting patients who were younger [≤ 45 years (27.6%), 46-55 (7.2%), >55 (2.6%); P < .0001)]; nondiabetic (9.5% versus 2.8%, P = .023); nonalcoholic (11.4% versus 6.6%, P = .056); and displayed negative HBV markers (10.2% versus 4.6%, P = .023). Only three patients with IgG-anti- HAV (-) were over 60 years. In conclusion, there is a frequent indication for HBV vaccination among cirrhotic and especially HAV vaccine for under 45 year old patients undergoing evaluation for OLT.

Crystal structure characterization of nautilus shell at different length scales.

In this work, we studied the shell structure of the Nautilus pompilius Linnaeus by using analytical techniques of scanning (SEM) and transmission electron microscopy (TEM) and X-ray diffraction. The main objective of this study is the structural characterization of Nautilus shell at different length levels, from micron to nano-scale. The results were also used to try to determine the shell structure mechanism of formation. The information obtained in this work will place our particular knowledge a closer step to understand how self-assembly works in nature, and will increase the opportunities of using this information in the future synthesis of new advanced materials.

Temperature effect on the synthesis of Au-Pt bimetallic nanoparticles.

Pt-Au bimetallic nanoparticles have been synthesized by the polyol method and stabilized with poly(vinylpyrrolidone) (PVP), modifying the temperature of synthesis. Interesting structure changes were observed in the nanoparticles as the temperature was varied. At lower temperatures no bimetallic nanoparticles were detected, but as the temperature increased bimetallic nanoparticles started to appear, commonly obtaining core-shell nanoparticles, always covered by the polymer. This originates the modification of the optical response of the system in the UV-visible region. An absorption peak centered at 520 nm at low temperatures was observed (100-110 degrees C); at higher temperatures (130-170 degrees C) there were non detectable absorption peaks, and finally at the two highest temperatures (180-190 degrees C) the reappearance of an absorption feature centered at 510 nm was noticed. These UV-visible results indirectly imply the composition of the surface of the particle. The structure of the particles has been determined using transmission electron microscopy and high-angle annular dark field (HAADF), the latter being a powerful technique to determine the structural composition of the particles and allowing a direct correlation of the optical response with their structural composition. X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) studies were also performed on the samples and their results support the idea of a Pt(core)-Au(shell) structure with the elements segregated from each other. The combination of these experimental techniques with calculated UV-vis absorption spectra allowed, in a reliable way, the elucidation of the nanoparticles structure and elemental distribution.