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OBJECTIVE: To identify baseline clinical and demographic characteristics associated with clinically important treatment responses in a randomized trial of nonsurgical therapies for fecal incontinence (FI). METHODS: Women (N = 296) with FI were randomized to loperamide or placebo- and manometry-assisted biofeedback exercises or educational pamphlet in a 2 × 2 factorial design. Treatment response was defined in 3 ways from baseline to 24 weeks: minimal clinically important difference (MID) of -5 points in St. Mark's score, ≥50% reduction in FI episodes, and combined St. Mark's MID and ≥50% reduction FI episodes. Multivariable logistic regression models included baseline characteristics and treatment groups with and without controlling for drug and exercise adherence. RESULTS: Treatment response defined by St. Mark's MID was associated with higher symptom severity (adjusted odds ratio [aOR] 1.20, 95% confidence interval [CI] 1.11-1.28) and being overweight vs normal/underweight (aOR 2.15, 95% CI 1.07-4.34); these predictors remained controlling for adherence. Fifty percent reduction in FI episodes was associated with the combined loperamide/biofeedback group compared with placebo/pamphlet (aOR 4.04, 95% CI 1.36-11.98), St. Mark's score in the placebo/pamphlet group (aOR 1.29, 95% CI 1.01-1.65), FI subtype of urge vs urge plus passive FI (aOR 2.39, 95% CI 1.09-5.25), and passive vs urge plus passive FI (aOR 3.26, 95% CI 1.48-7.17). Controlling for adherence, associations remained, except St. Mark's score. DISCUSSION: Higher severity of FI symptoms, being overweight, drug adherence, FI subtype, and combined biofeedback and medication treatment were associated with clinically important treatment responses. This information may assist in counseling patients, regarding efficacy and expectations of nonsurgical treatments of FI.
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Antidiarreicos/uso terapêutico , Terapia por Exercício/métodos , Incontinência Fecal/terapia , Loperamida/uso terapêutico , Educação de Pacientes como Assunto , Idoso , Biorretroalimentação Psicológica , Terapia Combinada , Incontinência Fecal/complicações , Feminino , Humanos , Manometria , Adesão à Medicação , Pessoa de Meia-Idade , Diferença Mínima Clinicamente Importante , Sobrepeso/complicações , Índice de Gravidade de Doença , Magreza/complicações , Resultado do TratamentoRESUMO
Image interpretation of Barrett's esophagus (BE) with volumetric laser endomicroscopy (VLE) can be enhanced by image processing software that highlights established features using a color-graded scale (intelligent real-time image segmentation, IRIS). This study aims to provide a description of IRIS features of various gastroesophageal tissue types using histologic correlation. A database of 80 VLE laser-marked targets with histologic correlation was reviewed for various tissue types. IRIS was applied off-line to the VLE scans, laser-marked targets were identified, and feature review was performed. Squamous epithelium targets (N = 7) showed IRIS layered architecture with lack of surface hyper-reflectivity and epithelial glands. Gastric cardia targets (N = 10) showed absent layering (100%) and surface hyper-reflectivity with epithelial glands (40%). Nondysplastic BE targets (N = 39) showed surface hyper-reflectivity (64%), epithelial glands (51%), and lack of layering (74%). Targets of BE with early neoplasia (N = 24), showed surface hyper-reflectivity (96%), epithelial glands (67%), and lack of layering (96%). IRIS features that characterize each tissue type appear to mirror the nonenhanced VLE counterparts that define them.
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Esôfago de Barrett/diagnóstico por imagem , Esôfago de Barrett/patologia , Neoplasias Esofágicas/diagnóstico por imagem , Neoplasias Esofágicas/patologia , Processamento de Imagem Assistida por Computador , Cárdia , Mucosa Esofágica/diagnóstico por imagem , Mucosa Esofágica/patologia , Esofagoscopia , Mucosa Gástrica/diagnóstico por imagem , Mucosa Gástrica/patologia , Humanos , Microscopia Intravital , Microscopia Confocal/métodos , SoftwareRESUMO
BACKGROUND: The mechanism by which obesity leads to damage independent of reflux is unclear. We aimed to determine the influence of obesity on mean nocturnal baseline impedance (MNBI), a functional measure of the epithelial barrier, in the presence and absence of acid reflux, using ambulatory pH impedance measurements. METHODS: Twenty-four-hour pH impedance studies performed off medications in Caucasian men with a normal endoscopic examination were assessed for level of acid exposure and MNBI. Four patient groups were studied: Group 1, Not obese and normal acid exposure; Group 2, Obese and normal acid exposure; Group 3, Not obese and increased acid exposure; and Group 4, Obese with increased acid exposure. RESULTS: One hundred patients were studied (25 in each group). Mean esophageal mucosal impedance (MI) was substantially lower in obese patients without reflux (Group 2) and non-obese patients with reflux (Group 3) compared to normal controls (non-obese, no reflux, Group 1). MI was progressively lower in the distal (vs the proximal) esophagus in GER patients, compared to those without GER. This difference persisted in the presence or absence of obesity. In contrast, in obese patients, the mean MI was significantly lower throughout the esophagus when compared to the non-obese patients and also persisted in the presence and absence of accompanying reflux. Obesity and reflux were both independently negatively correlated with MI. CONCLUSION: Obesity is associated with abnormal esophageal MNBI. In contrast to gastro-esophageal reflux, this decrease is pan-esophageal. These data may support a systemic mechanism by which obesity alters the esophageal barrier function.
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Mucosa Esofágica/fisiopatologia , Refluxo Gastroesofágico/etiologia , Refluxo Gastroesofágico/fisiopatologia , Obesidade/complicações , Adulto , Idoso , Impedância Elétrica , Monitoramento do pH Esofágico , Humanos , Concentração de Íons de Hidrogênio , Masculino , Pessoa de Meia-Idade , PermeabilidadeRESUMO
Barrett's esophagus (BE) is the only known precursor to esophageal adenocarcinoma (EAC). Based on striking aggregation of breast cancer and BE/EAC within families as well as shared risk factors and molecular mechanisms of carcinogenesis, we hypothesized that BE may be associated with breast cancer. Pedigree analysis of families identified prospectively at multiple academic centers as part of the Familial Barrett's Esophagus Consortium (FBEC) was reviewed and families with aggregation of BE/EAC and breast cancer are reported. Additionally, using a matched case-control study design, we compared newly diagnosed BE cases in Caucasian females with breast cancer (cases) to Caucasian females without breast cancer (controls) who had undergone upper endoscopy (EGD). Two familial pedigrees, meeting a stringent inclusion criterion, manifested familial aggregation of BE/EAC and breast cancer in an autosomal dominant inheritance pattern with incomplete penetrance. From January 2008 to October 2016, 2812 breast cancer patient charts were identified, of which 213 were Caucasian females who underwent EGD. Six of 213 (2.82%) patients with breast cancer had pathology-confirmed BE, compared to 1 of 241 (0.41%) controls (P-value < 0.05). Selected families with BE/EAC show segregation of breast cancer. A breast cancer diagnosis is marginally associated with BE. We postulate a common susceptibility between BE/EAC and breast cancer.
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Esôfago de Barrett/genética , Neoplasias da Mama/genética , Adulto , Estudos de Casos e Controles , Feminino , Predisposição Genética para Doença/genética , Humanos , Pessoa de Meia-Idade , Linhagem , Estudos Prospectivos , População Branca/genéticaRESUMO
INTRODUCTION: Carcinomas of the thyroid gland represent 3% of all malignancies, with 1.3 to 9.8% corresponding to anaplastic thyroid carcinomas (ATC). Metastases are present in 50% of patients when ATC is diagnosed. Gastrointestinal metastases are a rare finding in patients with thyroid carcinoma. CASE REPORT: A 68-year old gentleman with a history of papillary thyroid carcinoma (PTC) underwent surgery and radiopharmaceutical therapy. Restaging studies nine months later suggested wall thickening localizing to the distal stomach. Endoscopy results showed a large, infiltrative, subepithelial, and ulcerated gastric mass and biopsies revealed anaplastic thyroid carcinoma Conclusion. Incidental thickening or other findings in the stomach in a patient with ATC without gastrointestinal symptoms should be further investigated with endoscopy and biopsies to rule out gastric metastases from anaplastic thyroid carcinoma.
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BACKGROUND: Proton pump inhibitors (PPI) are inconsistently associated with osteoporotic fractures. Barrett's oesophagus (BO) patients are treated with high PPI doses for prolonged periods, but there are limited data on the incidence of osteoporosis and fractures in this group pf patients. AIM: To estimate the incidence of (and risk factors for) low bone mass (osteoporosis and/or osteopenia) related fractures in a population-based BO cohort. METHODS: All subjects with BO and a diagnosis of osteoporosis and fractures were identified using Rochester Epidemiology Project resources. The incidence rates of all and osteoporotic fractures in these subjects were compared to an age- and gender similar population in Olmsted County to determine standardised incidence ratios (SIR). Predictors were assessed using Cox proportional hazards models. RESULTS: Five hundred and twenty-one patients were included (median [IQR] age 61 [52, 72] years; 398 [76%] men) of whom 113 (21.7%) had fractures, and 46 (8.8%) had osteoporotic fractures. The incidence of all fractures and osteoporotic fractures was comparable to that of an age- and gender-matched population (SIR 1.09; 95% CI 0.92-1.29: SIR 1.05; 95% CI 0.85-1.29). PPI use, dose or duration of use was not associated with osteoporotic fracture risk (HR 0.87; 95% CI 0.12-6.39). Independent risk factors for osteoporotic fractures included older age, female gender and higher co-morbidity index. CONCLUSIONS: The incidence of osteoporotic fractures was not increased in BO patients compared to the general population. In addition, PPI use was not associated with increased fracture risk regardless of the duration of therapy or dose.
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Esôfago de Barrett/tratamento farmacológico , Esôfago de Barrett/epidemiologia , Fraturas por Osteoporose/epidemiologia , Inibidores da Bomba de Prótons/efeitos adversos , Distribuição por Idade , Idoso , Estudos de Casos e Controles , Estudos de Coortes , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Minnesota/epidemiologia , Fraturas por Osteoporose/induzido quimicamente , Modelos de Riscos Proporcionais , Inibidores da Bomba de Prótons/uso terapêutico , Fatores de Risco , Distribuição por SexoRESUMO
Background: Lung cancer is the leading cause of cancer-related deaths across the world. In this study, we present therapeutically relevant genetic alterations in lung adenocarcinoma of Indian origin. Materials and methods: Forty-five primary lung adenocarcinoma tumors were sequenced for 676 amplicons using RainDance cancer panel at an average coverage of 1500 × (reads per million mapped reads). To validate the findings, 49 mutations across 23 genes were genotyped in an additional set of 363 primary lung adenocarcinoma tumors using mass spectrometry. NIH/3T3 cells over expressing mutant and wild-type FGFR3 constructs were characterized for anchorage independent growth, constitutive activation, tumor formation and sensitivity to FGFR inhibitors using in vitro and xenograft mouse models. Results: We present the first spectrum of actionable alterations in lung adenocarcinoma tumors of Indian origin, and shows that mutations of FGFR3 are present in 20 of 363 (5.5%) patients. These FGFR3 mutations are constitutively active and oncogenic when ectopically expressed in NIH/3T3 cells and using a xenograft model in NOD/SCID mice. Inhibition of FGFR3 kinase activity inhibits transformation of NIH/3T3 overexpressing FGFR3 constructs and growth of tumors driven by FGFR3 in the xenograft models. The reduction in tumor size in the mouse is paralleled by a reduction in the amounts of phospho-ERK, validating the in vitro findings. Interestingly, the FGFR3 mutations are significantly higher in a proportion of younger patients and show a trend toward better overall survival, compared with patients lacking actionable alterations or those harboring KRAS mutations. Conclusion: We present the first actionable mutation spectrum in Indian lung cancer genome. These findings implicate FGFR3 as a novel therapeutic in lung adenocarcinoma.
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Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/genética , Resistencia a Medicamentos Antineoplásicos/genética , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Receptor Tipo 3 de Fator de Crescimento de Fibroblastos/genética , Adenocarcinoma/patologia , Adenocarcinoma de Pulmão , Adulto , Idoso , Animais , Proliferação de Células/efeitos dos fármacos , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Pulmonares/patologia , Masculino , Camundongos , Pessoa de Meia-Idade , Mutação , Células NIH 3T3 , Proteínas Proto-Oncogênicas p21(ras)/genética , Pirimidinas/administração & dosagem , Receptor Tipo 3 de Fator de Crescimento de Fibroblastos/antagonistas & inibidores , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND: The proportion of oesophageal adenocarcinoma that is detected concurrently with initial Barrett's oesophagus diagnosis is not well studied. AIM: To compare the proportion of prevalent adenocarcinoma vs. incident adenocarcinoma found during surveillance of Barrett's. METHODS: We performed a systematic search of MEDLINE, EMBASE and Web of Science (from their inception to 31 May 2015) for cohort studies in adults with Barrett's (nondysplastic Barrett's ± Barrett's with low-grade dysplasia) with minimum average follow-up of 3 years, and providing numbers of prevalent adenocarcinoma detected (concurrently with Barrett's diagnosis and up to 1 year afterwards) vs. incident adenocarcinoma detected (greater than 1 year after Barrett's diagnosis). Pooled weighted proportions of prevalent and incident adenocarcinoma were calculated, using a random effects model. RESULTS: On meta-analysis of 13 studies reporting on 603 adenocarcinomas in 9657 Barrett's patients, 85.1% of adenocarcinomas were classified as prevalent [95% confidence interval (CI), 78.1-90.2%) and 14.9% as incident (95% CI, 9.8-21.9%), with substantial heterogeneity (I(2) = 66%). Among nine studies reporting on 787 high-grade dysplasia and oesophageal adenocarcinomas in 8098 Barrett's patients, the proportion of prevalent high-grade dysplasia-oesophageal adenocarcinoma was similar at 80.5% (95% CI, 68.1-88.8%, I(2) = 87%). These results remained stable across multiple subgroup analyses including study quality, setting, duration of follow-up and presence of baseline dysplasia. CONCLUSIONS: In our meta-analysis, four of five patients diagnosed with adenocarcinoma or high-grade dysplasia at index endoscopy or within 1 year of Barrett's follow-up were considered to be prevalent cases. Continued efforts are needed to identify patients with Barrett's before the development of adenocarcinoma.
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Adenocarcinoma/epidemiologia , Esôfago de Barrett/epidemiologia , Neoplasias Esofágicas/epidemiologia , Adulto , Idoso , Endoscopia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , PrevalênciaAssuntos
Antígenos CD19/metabolismo , DNA Helicases/genética , Disceratose Congênita/terapia , Retardo do Crescimento Fetal/terapia , Deficiência Intelectual/terapia , Microcefalia/terapia , Receptores de Antígenos de Linfócitos T alfa-beta/metabolismo , Transplante de Células-Tronco , Antígenos CD19/genética , Disceratose Congênita/genética , Retardo do Crescimento Fetal/genética , Humanos , Lactente , Deficiência Intelectual/genética , Masculino , Microcefalia/genética , Mutação , Prognóstico , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Condicionamento Pré-Transplante/métodosRESUMO
Barrett's esophagus (BE) is among the most common conditions encountered by the gastroenterologist. In this document, the American College of Gastroenterology updates its guidance for the best practices in caring for these patients. These guidelines continue to endorse screening of high-risk patients for BE; however, routine screening is limited to men with reflux symptoms and multiple other risk factors. Acknowledging recent data on the low risk of malignant progression in patients with nondysplastic BE, endoscopic surveillance intervals are attenuated in this population; patients with nondysplastic BE should undergo endoscopic surveillance no more frequently than every 3-5 years. Neither routine use of biomarker panels nor advanced endoscopic imaging techniques (beyond high-definition endoscopy) is recommended at this time. Endoscopic ablative therapy is recommended for patients with BE and high-grade dysplasia, as well as T1a esophageal adenocarcinoma. Based on recent level 1 evidence, endoscopic ablative therapy is also recommended for patients with BE and low-grade dysplasia, although endoscopic surveillance continues to be an acceptable alternative. Given the relatively common recurrence of BE after ablation, we suggest postablation endoscopic surveillance intervals. Although many of the recommendations provided are based on weak evidence or expert opinion, this document provides a pragmatic framework for the care of the patient with BE.(AU)
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Humanos , Esôfago de Barrett/diagnóstico , Esôfago de Barrett/terapia , Programas de Rastreamento , Esôfago de Barrett/cirurgia , Fatores de Risco , Endoscopia Gastrointestinal/métodos , Técnicas de Ablação/métodos , Abordagem GRADERESUMO
Barrett's esophagus (BE) with high-grade dysplasia (HGD) defines a group of individuals at high risk of progression to esophageal adenocarcinoma (EA). Fluorescence in situ hybridization (FISH) has been shown to be useful for the detection of dysplasia and EA in endoscopic brushing specimens from BE patients. The aim of this study was to determine whether FISH in combination with histological findings would further identify more rapid progressors to EA. This is a retrospective cohort study of high-risk patients, having a history of biopsy-confirmed HGD without EA, with an endoscopic brushing specimen analyzed by FISH while undergoing endoscopic surveillance and treatment between April 2003 and October 2010. Brushing specimens were assessed by FISH probes targeting 8q24 (MYC), 9p21 (CDKN2A), 17q12 (ERBB2), and 20q13 (ZNF217) and evaluated for the presence of polysomy, defined as multiple chromosomal gains (displaying ≥ 3 signals for ≥ 2 probes). Specimens containing ≥ 4 cells exhibiting polysomy were considered polysomic. HGD was confirmed by at least two experienced gastrointestinal pathologists. Of 245 patients in this study, 93 (38.0%) had a polysomic FISH result and 152 (62.0%) had a non-polysomic FISH result. Median follow-up was 3.6 years (interquartile range [IQR] 2-5 years). Patients with a polysomic FISH result had a significantly higher risk of developing EA within 2 years (14.2%) compared with patients with a non-polysomic FISH result (1.4%, P < 0.001). These findings suggest that a polysomic FISH result in BE patients with simultaneous HGD identifies patients at a higher risk for developing EA compared with those with non-polysomy.
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Adenocarcinoma/genética , Esôfago de Barrett/genética , Inibidor de Quinase Dependente de Ciclina p18/genética , Neoplasias Esofágicas/genética , Hibridização in Situ Fluorescente/métodos , Proteínas Proto-Oncogênicas c-myc/genética , Receptor ErbB-2/genética , Transativadores/genética , Adenocarcinoma/patologia , Idoso , Esôfago de Barrett/patologia , Estudos de Coortes , Inibidor p16 de Quinase Dependente de Ciclina , Sondas de DNA , Progressão da Doença , Neoplasias Esofágicas/patologia , Esofagoscopia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Medição de RiscoRESUMO
BACKGROUND: Nystagmus in patients with multiple sclerosis (MS) is generally attributed to brainstem disease. Lesions in other regions may result in nystagmus. The identification of these other sites is enhanced by using 3-Tesla magnetic resonance imaging (3TMRI) due to increased signal-to-noise ratio. OBJECTIVE: We sought to evaluate the distribution of structural lesions and disruption of tracts in patients with horizontal nystagmus secondary to MS using 3TMRI. METHODS: Twenty-four patients (20 women, 4 men; age range 26-55 years) with horizontal nystagmus secondary to MS underwent 3TMRI brain scans; and 18 patients had diffusion tensor imaging (DTI) for tractography. RESULTS: Nystagmus was bidirectional in 11, right-sided in 6 and left-sided in 7. We identified 194 lesions in 20 regions within the neural integrator circuit in 24 patients; 140 were within the cortex and 54 were within the brainstem. Only two patients had no lesions in the cortex, and 9 had no lesions in the brainstem. There was no relationship between side of lesion and direction of nystagmus. Thirteen of 18 (72 %) had tract disruption with fractional anisotropy (FA) values below 0.2. FA was significantly lower in bidirectional compared to unidirectional nystagmus (p = 0.006). CONCLUSION: In MS patients with horizontal nystagmus, lesions in all cortical eye fields and their descending connections were evident. Technical improvements in tractography may help identify the specific site(s) resulting in nystagmus in MS.
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Imagem de Tensor de Difusão/métodos , Imageamento por Ressonância Magnética/métodos , Esclerose Múltipla/diagnóstico por imagem , Nistagmo Patológico/diagnóstico por imagem , Adulto , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND: Human papilloma virus (HPV) accounts for the most common cause of all virus-associated human cancers. Here, we describe the first graphic user interface (GUI)-based automated tool 'HPVDetector', for non-computational biologists, exclusively for detection and annotation of the HPV genome based on next-generation sequencing data sets. METHODS: We developed a custom-made reference genome that comprises of human chromosomes along with annotated genome of 143 HPV types as pseudochromosomes. The tool runs on a dual mode as defined by the user: a 'quick mode' to identify presence of HPV types and an 'integration mode' to determine genomic location for the site of integration. The input data can be a paired-end whole-exome, whole-genome or whole-transcriptome data set. The HPVDetector is available in public domain for download: http://www.actrec.gov.in/pi-webpages/AmitDutt/HPVdetector/HPVDetector.html. RESULTS: On the basis of our evaluation of 116 whole-exome, 23 whole-transcriptome and 2 whole-genome data, we were able to identify presence of HPV in 20 exomes and 4 transcriptomes of cervical and head and neck cancer tumour samples. Using the inbuilt annotation module of HPVDetector, we found predominant integration of viral gene E7, a known oncogene, at known 17q21, 3q27, 7q35, Xq28 and novel sites of integration in the human genome. Furthermore, co-infection with high-risk HPVs such as 16 and 31 were found to be mutually exclusive compared with low-risk HPV71. CONCLUSIONS: HPVDetector is a simple yet precise and robust tool for detecting HPV from tumour samples using variety of next-generation sequencing platforms including whole genome, whole exome and transcriptome. Two different modes (quick detection and integration mode) along with a GUI widen the usability of HPVDetector for biologists and clinicians with minimal computational knowledge.
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Genoma Humano , Neoplasias de Cabeça e Pescoço/virologia , Papillomaviridae/genética , Neoplasias do Colo do Útero/virologia , Integração Viral/genética , Cromossomos Humanos , Feminino , Genoma Viral , Genômica/métodos , Neoplasias de Cabeça e Pescoço/genética , Humanos , Papillomaviridae/isolamento & purificação , Neoplasias do Colo do Útero/genéticaRESUMO
Large yield and low temperature growth of nanostructures are key requirements for fulfilling the demand of large scale applications of nanomaterials. Here, we report a highly efficient chemical method to synthesize high quality hexagonal ZnO nanoparticle and nanorods utilizing the low temperature oxidation of metallic zinc powder in the presence of an appropriate catalyst. This one-step method has advantages such as low temperature (90 degrees C) and atmospheric pressure synthesis and a high yield (> 90%). Microstructure and optical properties of the as-synthesized ZnO nanoparticles are found to be identical or better than those of the commercial ZnO nanopower (Sigma-Aldrich). In particular, in comparison to the commercial nanopowder the as-grown ZnO nanorods and nanoparticles exhibit stronger UV absorption at 376 nm and intense UV photoluminescence emission at -382 nm, with negligible defect emission band. This method is suitable for large-scale production of nanosized ZnO and could be extended for the synthesis of other metal oxides.
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Cristalização/métodos , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Óxido de Zinco/química , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Refratometria , Propriedades de SuperfícieRESUMO
Though defects are invariably present in as-grown and purified carbon nanotubes (NTs), spectroscopic properties of defects in NTs have not been established yet. In this work, single walled (SW) and multiwalled (MW) carbon nanotubes (NTs) grown by chemical vapor deposition have been studied by high resolution transmission electron microscopy (HRTEM), Raman scattering and photoluminescence (PL), electron spin resonance (ESR) and thermo gravometric (TGA) analysis. Raman spectra of both SWNT and MWNT show additional features in the frequency range intermediate between 600-1300 cm(-1) and 1700-2600 cm(-1), in addition to well-known radial breathing modes, D- and G-bands. Room temperature PL studies show two broad but distinct peaks centered at approximately 2.05 eV and approximately 2.33 eV, for both SWNT and MWNT samples. TGA analysis shows very low impurity content in MWNT sample as compared to the SWNT sample. HRTEM analysis reveals various kinds of structural defects in nanotube wall. With the help of HRTEM and ESR studies, we argue that the intermediate frequency Raman modes and the visible PL from the pristine NTs are definite signatures of structural defects in the nanotubes.
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We report a new and highly efficient method to synthesize zinc oxide (ZnO) nanostructures having a variety of sizes and shapes. A simple chemical reaction is followed that utilizes the oxidation of metallic zinc in the presence of an appropriate catalyst. This one-step method has advantages such as low temperature and atmospheric pressure synthesis, high yield of more than 90% and excellent optical and crystalline properties of the product. X-ray diffraction pattern of the samples shows hexagonal phase of ZnO with particles size in the range of 60-75 nm. Scanning electron microscope and transmission electron microscope images of the ZnO show hexagonal and rod-shaped nanoparticles. UV-visible spectra of the dispersed samples show strong absorption peaks at approximately 378 nm. The photoluminescence spectra show a strong emission peak at approximately 388 nm indicating good optical characteristics. The product formed is found to be dependent on the ratio of the starting materials and on other reaction conditions such as temperature, time etc. This method is suitable for large-scale production of nanosized ZnO and could be extended for the synthesis of other metal oxides, such as MgO etc.
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Anaerobic treatability of synthetic sago wastewater was investigated in a laboratory anaerobic tapered fluidized bed reactor (ATFBR) with a mesoporous granular activated carbon (GAC) as a support material. The experimental protocol was defined to examine the effect of the maximum organic loading rate (OLR), hydraulic retention time (HRT), the efficiency of the reactor and to report on its steady-state performance. The reactor was subjected to a steady-state operation over a range of OLR up to 85.44 kg COD/(m3 x d). The COD removal efficiency was found to be 92% in the reactor while the biogas produced in the digester reached 25.38 m3/(m3 x d) of the reactor. With the increase of OLR from 83.7 kg COD/(m3 x d), the COD removal efficiency decreased. Also an artificial neural network (ANN) model using multilayer perceptron (MLP) has been developed for a system of two input variable and five output dependent variables. For the training of the input-output data, the experimental values obtained have been used. The output parameters predicted have been found to be much closer to the corresponding experimental ones and the model was validated for 30% of the untrained data. The mean square error (MSE) was found to be only 0.0146.