Stabilization of hybrid perovskite CH_3NH_3PbI_3 thin films by graphene passivation

We report the long-term stability of water-sensitive hybrid perovskites CH_3NH_3PbI_3 that were protected with monolayer graphene. This successful passivation was enabled by our development of a new water-free and polymer-free graphene transfer method. Monolayer graphene samples grown by plasma-enhanced chemical vapor deposition and transferred onto different substrates with the water/polymer-free method were found to preserve their high-quality characteristics after the transfer, as manifested by the studies of Raman, X-ray and ultraviolet photoemission spectroscopy (XPS and UPS), optical absorption, and sheet resistance. Additionally, XPS, UPS and optical absorption studies of fully graphene-covered CH_3NH_3PbI_3 thin films showed spectral invariance even after 3 months, which was in sharp contrast to the drastic spectral changes after merely one week in control CH_3NH_3PbI_3 samples without graphene protection. This successful demonstration of the graphene-enabled passivation and long-term stability of CH_3NH_3PbI_3 thin films therefore opens up a new pathway towards realistic photovoltaic applications of hybrid perovskites

Stabilization of hybrid perovskite CH_3NH_3PbI_3 thin films by graphene passivation

We report the long-term stability of water-sensitive hybrid perovskites CH_3NH_3PbI_3 that were protected with monolayer graphene. This successful passivation was enabled by our development of a new water-free and polymer-free graphene transfer method. Monolayer graphene samples grown by plasma-enhanced chemical vapor deposition and transferred onto different substrates with the water/polymer-free method were found to preserve their high-quality characteristics after the transfer, as manifested by the studies of Raman, X-ray and ultraviolet photoemission spectroscopy (XPS and UPS), optical absorption, and sheet resistance. Additionally, XPS, UPS and optical absorption studies of fully graphene-covered CH_3NH_3PbI_3 thin films showed spectral invariance even after 3 months, which was in sharp contrast to the drastic spectral changes after merely one week in control CH_3NH_3PbI_3 samples without graphene protection. This successful demonstration of the graphene-enabled passivation and long-term stability of CH_3NH_3PbI_3 thin films therefore opens up a new pathway towards realistic photovoltaic applications of hybrid perovskites

Klebsiella pneumoniae Bacteremia and Capsular Serotypes, Taiwan

Capsular serotypes of 225 Klebsiella pneumoniae isolates in Taiwan were identified by using PCR. Patients infected with K1 serotypes (41 isolates) had increased community-onset bacteremia, more nonfatal diseases and liver abscesses, lower Pittsburgh bacteremia scores and mortality rates, and fewer urinary tract infections than patients infected with non–K1/K2 serotypes (147 isolates)

Predicting Hospital-Acquired Infections by Scoring System with Simple Parameters

BACKGROUND: Hospital-acquired infections (HAI) are associated with increased attributable morbidity, mortality, prolonged hospitalization, and economic costs. A simple, reliable prediction model for HAI has great clinical relevance. The objective of this study is to develop a scoring system to predict HAI that was derived from Logistic Regression (LR) and validated by Artificial Neural Networks (ANN) simultaneously. METHODOLOGY/PRINCIPAL FINDINGS: A total of 476 patients from all the 806 HAI inpatients were included for the study between 2004 and 2005. A sample of 1,376 non-HAI inpatients was randomly drawn from all the admitted patients in the same period of time as the control group. External validation of 2,500 patients was abstracted from another academic teaching center. Sixteen variables were extracted from the Electronic Health Records (EHR) and fed into ANN and LR models. With stepwise selection, the following seven variables were identified by LR models as statistically significant: Foley catheterization, central venous catheterization, arterial line, nasogastric tube, hemodialysis, stress ulcer prophylaxes and systemic glucocorticosteroids. Both ANN and LR models displayed excellent discrimination (area under the receiver operating characteristic curve [AUC]: 0.964 versus 0.969, p = 0.507) to identify infection in internal validation. During external validation, high AUC was obtained from both models (AUC: 0.850 versus 0.870, p = 0.447). The scoring system also performed extremely well in the internal (AUC: 0.965) and external (AUC: 0.871) validations. CONCLUSIONS: We developed a scoring system to predict HAI with simple parameters validated with ANN and LR models. Armed with this scoring system, infectious disease specialists can more efficiently identify patients at high risk for HAI during hospitalization. Further, using parameters either by observation of medical devices used or data obtained from EHR also provided good prediction outcome that can be utilized in different clinical settings

Clinical Features, Antimicrobial Susceptibilities, and Outcomes of Elizabethkingia Meningoseptica (Chryseobacterium Meningosepticum) Bacteremia at a Medical Center in Taiwan, 1999-2006

A total of 118 patients with Elizabethkingia meningoseptica bacteremia at a medical center in Taiwan from 1999 to 2006 were studied. Minimum inhibitory concentrations (MICs) of 99 preserved isolates were determined. The incidence (per 100, 000 admissions) of E. meningoseptica bacteremia increased from 7.5 in 1996 to 35.6 in 2006 (p=0.006). Among them, 84% presented with fever, 86% had nosocomial infections, and 60% had acquired the infection in intensive care units (ICUs). The most common underlying diseases were malignancy (36%) and diabetes mellitus (25%). Seventy-eight percent of patients had primary bacteremia, followed by pneumonia (9%), soft tissue infection, and catheter-related bacteremia (6%) . Forty-five patients (38%) had polymicrobial bacteremia. Overall, the 14-day mortality was 23.4%. Multivariate analysis revealed E. meningoseptica bacteremia acquired in an ICU (p=0.048, odds ratio [OR] 4.23) and presence of effective antibiotic treatment after the availability of culture results ( p=0.049, OR 0.31) were independent predictors of 14-day mortality. The 14- day mortality was higher among patients receiving carbapenems (p=0.046) than fluoroquinolones or other antimicrobial agents. More than 80 % of the isolates tested were susceptible to trimethoprim- sulfamethoxzole, moxifloxacin, and levofloxacin. The MIC50 and MIC90 of the isolates to tigecycline and doxycycline were both 4 mu g/mL and 8 mu g/ml, respectively

Clinical Features and Outcome of Tuberculosis in Solid Organ Transplant Recipients

Background: Taiwan is an area with moderate to high incidence of Mycobacterium tuberculosis infection. The risk of M tuberculosis infection in transplantation recipients is considered to be significant. Our aim in this study was to investigate the clinical spectrums of M tuberculosis– infected transplantation recipients in a southeast Asian country, Taiwan. Methods: We retrospectively analyzed the demographic data, clinical features, treatment, and outcome of M tuberculosis infection in kidney, heart, and liver transplant recipients from May 1996 to April 2005 at the National Taiwan University Hospital. Results: Fifteen patients who had received solid organ transplantation developed tuberculosis(kidney duration from transplantation to diagnosis of tuberculosis was 31 months. The cumulative incidence of posttransplantation tuberculosis was 2.0% (15/ 760), ie, times that of the general population. Ten patients (66.7%) had pulmonary tuberculosis, 1 (6.7%) had extrapulmonary tuberculosis, and 4 ( 26.7%) had disseminated tuberculosis. Nine patients completed the anti- tuberculosis treatment; the median treatment duration was 12 months ( pulmonary: 9 months; extrapulmonary: 13.5 months). No treatment failure was noted in patients receiving the complete treatment course. The graft failure and mortality rates of post-transplantation tuberculosis were 13.3 % each ( 2/15). The tuberculosis-associated mortality rate was 6.7% ( 1/15 ). Conclusions: Cumulative incidence of tuberculosis was slightly higher in transplant recipients than in the general population in Taiwan. Conventional 4-combined anti- tuberculosis regimen for 12 months can treat the potentially fatal infection successfully in posttransplantation tuberculosis patients without recurrence. KEY INDEXING TERMS : Solid organ transplantation; Tuberculosis; Post- transplantation tuberculosis. [Am J Med Sci 2007;334(2):106–110.

The prevalence of rectal carriage of Klebsiella pneumoniae amongst diabetic patients and their clinical relevance in Taiwan: A five-year prospective study

Background/purpose: Pyogenic liver abscess (PLA) and bacteremia caused by Klebsiella pneumoniae is a common complication among patients with diabetes mellitus (DM). The aim of this study is to investigate the prevalence of rectal carriage and serotype distribution of K. pneumoniae amongst DM patients and their clinical relevance. Methods: We prospectively collected rectal swabs for K. pneumoniae culture in asymptomatic DM patients from March 2008 to June 2009. Seven capsular serotypes that were commonly associated with PLA were determined by capsular polysaccharide synthesis (cps) genotyping. Microbiologically confirmed bacterial infections were evaluated 1 and 5 years after initial enrolment of the patients. Results: A total of 100 male and 62 female patients (mean age, 56.6 years) were enrolled. Of these, 77 (47.5%) had rectal K. pneumoniae colonization. Colonizers were older than non-colonizers (p = 0.03). Sex, fasting blood glucose, and initial HbA1C were not statistically different (p = 0.26, 0.18, and 0.31, respectively). Among the 65 available isolates, 22 (33.8%) belonged to the seven main serotypes. During the 5-year's follow-up, 21 patients developed microbiologically documented bacterial infections but none of them developed PLA and bacteremia. Risk factors for bacterial infection within 5 years included initial glycosylated hemoglobin (HbA1C) > 10% or first-year average HbA1C > 10%. Conclusion: Although nearly half of asymptomatic DM patients had rectal carriage of K. pneumoniae and one-third of them colonized by isolates belonging to the seven serotypes related to PLA, none of them subsequently developed PLA and colonized patients did not have higher risk of microbiologically confirmed bacterial infections. Keywords: Klebsiella pneumoniae, Pyogenic liver abscess, Diabetes mellitus, Bacterial infections, Rectal carriag

Bidirectional Influences of Cranberry on the Pharmacokinetics and Pharmacodynamics of Warfarin with Mechanism Elucidation

Cranberry is a dietary supplement popularly used for the prophylaxis of urinary tract infection. Interestingly, cranberry–warfarin interactions in clinical reports have shown bidirectional outcomes. (±) Warfarin, a widely prescribed anticoagulant, but with a narrow therapeutic index, contains equal amounts of S- and R-warfarin, of which S-warfarin is more active. The aim of this study was to investigate the effects of different ingestion times of cranberry on the pharmacokinetics and pharmacodynamics of warfarin. Rats were orally administered (±) warfarin (0.2 mg/kg) with and without cranberry (5.0 g/kg) at 0.5 h prior to the warfarin, and at 10 h after the warfarin. The plasma concentrations of S- and R-warfarin were determined by LC/MS. The results indicate that cranberry ingested at 0.5 h before (±) warfarin significantly decreased the systemic exposures of S-warfarin and R-warfarin. Conversely, when cranberry was ingested at 10 h after (±) warfarin, the elimination of S-warfarin was significantly inhibited, and the anticoagulation effect of (±) warfarin was significantly enhanced. The results of the mechanism studies indicate that cranberry activated the breast cancer resistance protein (BCRP), which mediated the efflux transports of S-warfarin and R-warfarin. Moreover, the metabolites of cranberry inhibited cytochrome P450 (CYP) 2C9, the main metabolizing enzyme for S-warfarin. In conclusion, cranberry affected the pharmacokinetics of (±) warfarin in a bidirectional manner by activating the BCRP by CJ during absorption and inhibiting the BCRP and CYP2C9 by CMs during elimination, depending on the ingestion time of CJ. The combined use of cranberry with warfarin should be avoided

Revisiting the association between vitamin D deficiency and active tuberculosis: A prospective case-control study in Taiwan

Background: To revisit the association between vitamin D deficiency (VDD, defined as serum 25(OH)D < 20 ng/ml) and incident active tuberculosis (TB), after two potentially underpowered randomized trials showed statistically non-significant 13%–22% decrease in TB incidence in vitamin D supplementation groups. Methods: We prospectively conducted an age/sex-matched case–control study that accounting for body-mass index (BMI), smoking, and other confounding factors to examine the association between VDD and active TB among non-HIV people in Taiwan (latitude 24°N), a high-income society which continues to have moderate TB burden. Results: We enrolled 62 people with incident active TB and 248 people in control group. The TB case patients had a significantly higher proportion of VDD compared to the control group (51.6% vs 29.8%, p = 0.001). The 25(OH)D level was also significantly lower in TB patients compared to control group (21.25 ± 8.93 ng/ml vs 24.45 ± 8.36 ng/ml, p = 0.008). In multivariable analysis, VDD (adjusted odds ratio [aOR]: 3.03, p = 0.002), lower BMI (aOR: 0.81, p < 0.001), liver cirrhosis (aOR: 8.99, p = 0.042), and smoking (aOR: 4.52, p = 0.001) were independent risk factors for incident active TB. Conclusions: VDD is an independent risk factor for incident active TB. Future randomized trials examining the effect of vitamin D supplementation on TB incidence should focus on people with a low BMI or other risk factors to maximize the statistical power