Metal-free adsorption and photodegradation methods for methylene blue dye removal using different reduction grades of graphene oxide.

The release of organic pollutants and dyes into the environment by industries has had profound and harmful effects on both humans and ecosystems. Graphene oxide (GO) and its reduced form have been investigated for their effectiveness in removing pollutant dyes. GO nano-powder was synthesized using an improved version of Hummer's method and subsequently thermally reduced at various temperatures, including 125, 150, 175, and 200 °C, under vacuum conditions. In the X-ray diffraction spectra, an intense (001) diffraction peak was initially observed at 9.136° (2θ) for pristine GO. This peak gradually shifted towards higher angles as the reduction process took place and eventually disappeared when the GO was reduced at 200 °C. The intensity ratio of the D and G bands (ID/IG ratio) for GO nano-powder in the Raman spectra decreased from 0.94 to 0.76 due to the reduction process. The FTIR spectra of GO and reduced graphene oxide (rGO) also illustrated the reduction process. The bandgap of pristine GO significantly decreased from 2.31 to 0.73 eV, as determined by ultraviolet-visible (UV-Vis) diffuse reflectance spectrophotometry during the reduction process. The surface area and pore volume of both pristine GO and rGO-150 were determined using the BET (Brunauer-Emmett-Teller) and BJH (Barrett-Joyner-Halenda) methods. The results indicated an increase in the BET surface area from 6.61 to 7.86 m2/g and a corresponding enhancement in pore volume from 0.118 to 0.128 cc/g after reduction. The adsorption and photocatalytic degradation behavior of pristine GO and reduced graphene oxides (rGOs) were examined using methylene blue dye. The pristine GO demonstrated impressive adsorption capability, effectively removing the dye by 85.78 % within just 15 min and achieving nearly 97 % removal after 4 h. In contrast, the highest photocatalytic degradation of methylene blue, about 47.58 %, was attained for the rGO sample reduced at 150 °C under the illumination of visible light.

Solution-processed CZTS thin films and its simulation study for solar cell applications with ZnTe as the buffer layer.

Using zinc tellurium (ZnTe) as the buffer layer in the Cu2ZnSnS4 (CZTS)-based solar cells showed an improvement in overall efficiency. ZnTe is investigated as an alternative to replace the conventional toxic Cd-contained buffer layers. It may also reduce the overall cost of these cells as both layers (ZnTe and CZTS) have eco-friendly and earth-abundant constituents. The sol-gel spin coating method is used for the deposition of CZTS thin films on the corning glass substrates. The X-ray diffraction studies showed the peaks corresponding to (112), (200), (220), and (312) planes which confirmed the formation of the essential kesterite phase. The optical band gap of the deposited films was found at around 1.45 eV by the UV-visible-NIR spectrophotometer. The optimum thickness of the absorber layer (CZTS) and buffer layer (ZnTe) was investigated based on the performance of the ZnO:Al/ZnO/ZnTe/CZTS/Mo cell structure by using the AMPS-1D simulation tool. In contrast, the tool was molded by the experimentally investigated data for the constituent materials of the cell structure. The solar cells' efficiency was increased by 23.47% at 2500 nm and 50 nm thickness of the CZTS and ZnTe layers, respectively. In addition, it was analyzed and found that the current density value showed an improvement with operating temperature as it is one of the requirements in the high solar radiation areas where the temperature even rises more than 50 °C in the summer.

Property Modulation of Graphene Oxide Incorporated with TiO2 for Dye-Sensitized Solar Cells.

Graphene oxide (GO) nano-powder is synthesized by the modified Hummer's method, and further thin films are deposited by using the water solution of GO through spin-coating. These films are thermally reduced along with the synthesized GO nano-powder at 50 to 200 °C in a high vacuum. Microstructural, electrical, and optical properties are expectedly controlled by thermal reduction. The electronic properties of GO are investigated by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure. The reduction is confirmed by Raman spectroscopy. The work function and band gap of GO are tuned with the thermal reduction. The changes in properties of GO are not linear, and anomalous changes are observed for the reduction around 150 °C. Pristine and reduced GO nano-powder is incorporated into TiO2 paste to be the photoanode for dye-sensitized solar cells (DSSCs). It is observed that the performance of the fabricated cells is significantly enhanced for the GO reduced at 150 °C, and the cell exhibited a significant increment of ∼23% for the power conversion efficiency in comparison to DSSC based on an unmodified TiO2 photoanode.

Calculation of electronic and optical properties of methylammonium lead iodide perovskite for application in solar cell.

Organic-inorganic metal halide perovskite materials, i.e., ABX3 (A = methylammonium, B = Pb, X = Cl, Br, I) have been proved to be outstanding for solar energy conversion. They provide a solution to renewable energy problems with good efficiency and cost-effective technology. Here, we report the initial calculations done by solving Kohn-Sham equations by the use of density function theory. The electronic structural and band gap of CH3NH3PbI3 material are obtained by using different exchange-correlation potential (PBE, PBE-sol, GGA). Further, solar cell devices with CH3NH3PbI3 as absorption layer and CdS/TiO2/ZnTe as buffer layer have been modeled; device physics is discussed and performance of solar cell structure is analyzed in terms of short circuit current density, open circuit voltage, efficiency, fill factor, and quantum efficiency. The maximum efficiency of CH3NH3PbI3 solar cell is found to be 19.6% with TiO2 buffer layer, whereas efficiency with ZnTe buffer layer is also comparable which is 19.5%. Further the effect of layer thickness and temperature are analyzed for maximum efficiency.

Type-1 Seronegative Autoimmune Pancreatitis: A Rare Case of Autoimmune Pancreatitis with Sclerosing Cholangitis and Hashimoto's Disease.

Autoimmune pancreatitis (AIP) is very rarely reported in the literature. It is one of the immunoglobulin-G (IgG) related diseases that commonly presents with abdominal pain, mass, jaundice, and weight changes. The disease also has extrapancreatic manifestations, of which the most common is autoimmune sclerosing cholangitis. We report a case of autoimmune pancreatitis that was further found to be associated with Hashimoto's thyroiditis and sclerosing cholangitis. The clinical manifestations vary and it is important to exclude pancreatic malignancy before diagnosing any patient with AIP. Although further studies need to be done, currently the treatment of choice is steroid therapy. Physicians should also screen patients for other autoimmune diseases to rule out any concern.

Differentiation of pancreatic ductal adenocarcinoma from other neoplastic solid pancreatic lesions: a tertiary oncology center experience.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC), pancreatic neuroendocrine tumors (pNET), and metastatic lesions (pMET) are the most common neoplastic solid pancreatic lesions (SPLs). Early diagnosis enables prompt treatment. OBJECTIVE: To identify factors differentiating PDAC from non-PDAC lesions and assess the accuracy of EUS-guided FNA. DESIGN AND SETTING: Retrospective tertiary center. PATIENTS AND INTERVENTION: Consecutive patients referred for EUS evaluation of SPLs from 2004 to 2011. MAIN OUTCOME MEASUREMENTS: Pretest (preceding EUS-guided FNA [EUS-FNA]) predictors of PDAC among neoplastic SPLs and accuracy of EUS-FNA. RESULTS: A total of 1333 EUS scans with 1108 EUS-FNAs were performed for pancreatic lesions. Of the 672 patients with neoplastic SPLs, 528 had PDAC and 144 non-PDAC. The sensitivity, specificity, positive predictive value, and accuracy of EUS-FNA for the diagnosis of PDAC were 97.3%, 99.3%, 99.8%, and 97.8%, respectively. Years of EUS experience significantly correlated with fewer needle passes (Rs = -0.18, P < .001). Controlling for all potential confounders, multivariable regression analysis demonstrated that patients with PDAC compared with pNETs and pMETs were older (odds ratio [OR] 4.42; 95% confidence interval [CI], 2.1-9.5; P < .001), had weight loss (OR 3.0; 95% CI, 1.6-5.4; P < .001), hyperbilirubinemia (OR 3.7; 95% CI, 1.8-7.5; P < .001), elevated CA19-9 (OR 6.9; 95% CI, 2.4-20.3; P < .01), evidence of arterial invasion (OR 6.5; 95% CI, 2.7-15.4; P < .001), and PD dilation (OR 3.3; 95% CI, 1.8-5.9; P < .001). LIMITATIONS: Retrospective design, single center. CONCLUSIONS: When evaluating neoplastic SPLs, demographic, clinical, laboratory, and imaging characteristics can reliably discern and suggest PDAC. In addition, EUS-FNA is exceedingly sensitive and specific for PDAC.

Comparison of the utility of covered metal stents versus uncovered metal stents in the management of malignant biliary strictures in 749 patients.

BACKGROUND: Self-expandable metal stents (SEMSs) are used to relieve malignant biliary obstruction. OBJECTIVE: To compare outcomes between covered self-expandable metal stents (CSEMSs) and uncovered self-expandable metal stents (USEMSs) in malignant biliary obstruction. DESIGN: Retrospective cohort study. SETTING: Tertiary cancer center. PATIENTS: Patients with malignant biliary obstruction. INTERVENTIONS: Placement of CSEMS or USEMS. MAIN OUTCOME MEASUREMENTS: Time to recurrent biliary obstruction (TRO), overall survival (OS), and adverse events. RESULTS: From January 2000 to June 2011, 749 patients received SEMSs: 171 CSEMSs and 578 USEMSs. At 1 year, there was no significant difference in the percentage of patients with recurrent obstruction (CSEMSs, 35% vs USEMSs, 38%) and survival (CSEMSs, 45% vs USEMSs, 49%). There was no significant difference in the median OS (CSEMSs, 10.4 months vs USEMSs, 11.8 months; P = .84) and the median TRO (CSEMSs, 15.4 months vs USEMSs, 26.3 months; P = .61). The adverse event rate was 27.5% for the CSEMS group and 27.7% for the USEMS group. Although tumor ingrowth with recurrent obstruction was more common in the USEMS group (76% vs 9%, P < .001), stent migration (36% vs 2%, P < .001) and acute pancreatitis (6% vs 1%, P < .001) were more common in the CSEMS group. LIMITATIONS: Retrospective study. CONCLUSIONS: There was no significant difference in the patency rate or overall survival between CSEMSs and USEMSs for malignant distal biliary strictures. The CSEMS group had a significantly higher rate of migration and pancreatitis than the USEMS group. No significant SEMS-related adverse events were observed in patients undergoing neoadjuvant chemoradiation or surgical resection.

Many patients who undergo surgery for colorectal cancer receive surveillance colonoscopies earlier than recommended by guidelines.

BACKGROUND & AIMS: Patients treated with surgery for colorectal cancer (CRC) should undergo colonoscopy examinations 1, 4, and 9 years later, to check for cancer recurrence. We investigated the use patterns of surveillance colonoscopies among Medicare patients. METHODS: We used the Surveillance, Epidemiology and End Results (SEER)-Medicare linked database to identify patients who underwent curative surgery for colorectal cancer from 1992 to 2005 and analyzed the timing of the first 3 colonoscopies after surgery. Early surveillance colonoscopy was defined as a colonoscopy, for no reason other than surveillance, within 3 months to 2 years after a colonoscopy examination with normal results. RESULTS: Approximately 32.1% and 27.3% of patients with normal results from their first and second colonoscopies, respectively, underwent subsequent surveillance colonoscopies within 2 years (earlier than recommended). Of patients who were older than 80 years at their first colonoscopy, 23.6% underwent a repeat procedure within 2 years for no clear indication. In multivariable analysis, early surveillance colonoscopy was not associated with sex, race, or patients' level of education. There was significant regional variation in early surveillance colonoscopies among the Surveillance, Epidemiology, and End Results regions. There was a significant trend toward reduced occurrence of second early surveillance colonoscopies. CONCLUSIONS: Many Medicare enrollees who have undergone curative resection for colorectal cancer undergo surveillance colonoscopy more frequently than recommended by the guidelines. Reducing overuse could free limited resources for appropriate colonoscopy examinations of inadequately screened populations.

Effect of mental disorders on diagnosis, treatment, and survival of older adults with colon cancer.

OBJECTIVES: To evaluate the extent to which preexisting mental disorders influence diagnosis, treatment, and survival in older adults with colon cancer. DESIGN: Retrospective cohort study. SETTING: The Surveillance, Epidemiology and End Results (SEER)-Medicare linked database. PARTICIPANTS: Eighty thousand six hundred seventy participants, aged 67 and older with a diagnosis of colon cancer. MEASUREMENTS: The association between the presence of a preexisting mental disorder and the stage of colon cancer at diagnosis, receipt of cancer treatment, and overall and colon cancer-specific mortality were assessed using Cox proportional hazards regression and logistic regression. RESULTS: Participants with mental disorders were more likely to have been diagnosed with colon cancer at autopsy (4.4% vs 1.1%; P<.001) and at an unknown stage of cancer (14.6% vs 6.2%; P<.001); to have received no surgery, chemotherapy, or radiation therapy (adjusted risk ratio (ARR)=2.09, 95% confidence interval (CI)=1.86-2.35); and to have received no chemotherapy for Stage 3 cancer (ARR=1.63, 95% CI=1.49-1.79). The rate of overall mortality (hazard ratio (HR)=1.33, 95% CI=1.31-1.36) and colon cancer-specific mortality (HR=1.23, 95% CI=1.19-1.27) was substantially higher in participants with a preexisting mental disorder than in their counterparts. All of these associations were particularly pronounced in participants with psychotic disorders and those with dementia. CONCLUSION: Public health initiatives are needed to improve colon cancer detection and treatment in older adults with mental disorders.

Predictors of colorectal cancer following a negative colonoscopy in the Medicare population.

BACKGROUND: The incidence of colorectal cancer following a normal colonoscopy in the Medicare population is not known. METHODS: A 5% national sample of Medicare enrollees from 1996 to 2005 was used to identify patients undergoing complete colonoscopy. A colonoscopy not associated with any procedure (e.g., biopsy, polypectomy or fulguration) was defined as a negative colonoscopy. Patients with history of inflammatory bowel disease, colorectal cancer or death within 12 months of colonoscopy were excluded. A multivariable model was constructed to evaluate the factors associated with a new diagnosis of colorectal cancer in the period from 12 to 120 months following the negative colonoscopy. RESULTS: Among 200,857 patients (mean age 74 years, 61% female, 92% White) with a negative colonoscopy, the incidence of colorectal cancer was 1.8 per 1,000 person-years. The incidence rate for matched follow-up periods decreased from 2.0/1,000 person-years for patients undergoing colonoscopy during 1996-2000 to 1.2/1,000 person years during 2001-2005. Multivariate analysis revealed a significant regional variation in the incidence of colorectal cancer following a negative colonoscopy. The incidence was higher in patients >85 years, males and patients who underwent a negative colonoscopy by a non-gastroenterologist or endoscopist in the lowest volume quartile. On stratified analyses, endoscopist volume was a significant predictor for non-gastroenterologists only. CONCLUSIONS: The specialty and experience of the endoscopist are significant predictors of the incidence rate of colorectal cancer in Medicare patients with a negative colonoscopy.

Overuse of screening colonoscopy in the Medicare population.

BACKGROUND: All relevant authorities recommend an interval of 10 years between normal screening colonoscopies. We assessed the timing of repeated colonoscopies after a negative screening colonoscopy finding in a population-based sample of Medicare patients. METHODS: A 5% national sample of Medicare enrollees from 2000 through 2008 was used to identify average-risk patients undergoing screening colonoscopy between 2001 and 2003. Colonoscopy was classified as a negative screening examination finding if no indication other than screening were in the claims and if no biopsy, fulguration, or polypectomy was performed. Time to repeated colonoscopy was calculated. RESULTS: Among 24,071 Medicare patients who had a negative screening colonoscopy finding in 2001 through 2003, 46.2% underwent a repeated examination in fewer than 7 years. In 42.5% of these patients (23.5% of the overall sample), there was no clear indication for the early repeated examination. In patients aged 75 to 79 years or 80 years or older at the time of the initial negative screening colonoscopy result, 45.6% and 32.9%, respectively, received a repeated examination within 7 years. In multivariable analyses, male sex, more comorbidities, and colonoscopy by a high-volume colonoscopist or in an office setting were associated with higher rates of early repeated colonoscopy without clear indication, while those 80 years or older had a reduced risk. There were also marked geographic variations, from less than 5% in some health referral regions to greater than 50% in others. CONCLUSIONS: A large proportion of Medicare patients who undergo screening colonoscopy do so more frequently than recommended. Current Medicare regulations intending to limit reimbursement for screening colonoscopy to every 10 years would not appear to be effective.

Antiviral therapy reduces risk of hepatocellular carcinoma in patients with hepatitis C virus-related cirrhosis.

BACKGROUND & AIMS: The effects of antiviral therapy on prevention of hepatocellular carcinoma (HCC) in patients with hepatitis C virus (HCV)-related cirrhosis are unclear. We performed a systematic review and meta-analysis to assess HCC risk reduction in patients with HCV-related cirrhosis who have received antiviral therapy. METHODS: Twenty studies (4700 patients) were analyzed that compared untreated patients with those given interferon (IFN) alone or ribavirin. Risk ratios (RRs) determined effect size using a random effects model. RESULTS: Pooled data showed reduced HCC risk in the treatment group (RR, 0.43; 95% confidence interval [CI], 0.33-0.56), although the data were heterogenous (chi(2) = 59.10). Meta-regression analysis showed that studies with follow-up durations of more than 5 years contributed to heterogeneity. Analysis of 14 studies (n = 3310) reporting sustained virologic response (SVR) rates with antiviral treatment showed reduced HCC risk in patients with an SVR, compared with nonresponders (RR, 0.35; 95% CI, 0.26-0.46); the maximum benefits were observed in patients treated with ribavirin-based regimens (RR, 0.25; 95% CI, 0.14-0.46). Meta-analysis of 4 studies assessing the role of maintenance IFN in nonresponders did not show HCC risk reduction (RR, 0.58; 95% CI, 0.33-1.03). No publication bias was detected by the Egger test analysis (P > 0.1). CONCLUSIONS: The risk of HCC is reduced among patients with HCV who achieve an SVR with antiviral therapy. Maintenance therapy with IFN does not reduce HCC risk among patients who do not respond to initial therapy. View this article's video abstract atwww.cghjournal.org.

Giant trichobezoar and gastric perforation in a normal healthy woman.

We present a case report of a mentally healthy woman who had gastric trichobezoar leading to perforation. A pertinent review of literature is included.