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The Application of Flame Atomic Absorption Spectrometry for Gold Determination in Some of Its Bearing Rock.

American Journal of Analytical Chemistry 2015年第5期6卷 411-421页

作者： hisham k. fouad Randa M. Elrak.iby Mohamed D. Hashim Analytical Chemistry Department Nuclear Materials Authority Cairo Egypt

A developed method was designed for gold determination directly in organic medium in some sedimentary rock. (fine sandstone, carbonates), pyrite, serpentine and international standard gold sample (MA-1a) using flame atomic absorption spectroscopy (FAAS). Instrumental parameters;burner angle, fuel flow rate, band pass and burner height together with chemical parameters;different media, leaching and interference effect were optimized to improve gold determination. Selective leaching using a new mixture (5% k.N, 5% Na2S2O3 and hydrogen peroxide) offered maximum leaching percentage of gold (>99%) with minimal concentration of accompanying elements. Extraction parameters using methyl isobutyl k.tone (MIBk. from 3 M HCl were optimized for more than 99% gold extraction, followed by scrubbing using 0.1 M HCl. Gold was determined directly in organic phase. Beer’s law was obeyed from 0.01 μg/ml to 10 μg/ml. Standard deviation (from 0.017 to 1.05) and percentage error (from 1.5% to 2.5%) using the present developed AAS method were calculated.

关键词： Gold Determination MIBk Extraction FAAS

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Barrett's esophagus:Prevalence and risk.factors in patients with chronic GERD in Upper Egypt

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World Journal of Gastroenterology 2009年第28期15卷 3511-3515页

作者： Yasser M fouad Madiha M Mak.louf Heba M Tawfik.Hussein El Amin Wael Abdel Ghany hisham R El-k.ayat Department of Tropical Medicine and Gastroenterology Minya University Department of Pathology Minya University Department of Internal Medicine Gastroenterology Unit Assuit University Department of Gastroenterology Theodore Bilharz Research Institute

AIM： To determine the prevalence and possible risk.factors of Barrett＇s esophagus （BE） in patients with chronic gastroesophageal reflux disease （GERD） in EI Minya and Assuit, Upper Egypt. METHODS： One thousand consecutive patients with chronic GERD symptoms were included in the study over 2 years. They were subjected to history tak.ng including a questionnaire for GERD symptoms, clinical examination and upper digestive tract endoscopy. Endoscopic signs suggestive of columnar-lined esophagus （CLE） were defined as mucosal tongues or an upward shift of the squamocolumnar junction. BF was diagnosed by pathological examination when specialized intestinal metaplasia was detected histologically in suspected CLE. pH was monitored in 40 patients. RESULTS： BE was present in 7.3% of patients with chronic GERD symptoms, with a mean age of 48.3 ± 8.2 years, which was significantly higher than patients with GERD without BE （37.4 ± 13.6 years）. Adenocarcinoma was detected in eight cases （0.8%）, six of them in BE patients. There was no significant difference between patients with BE and GERD regarding sex, smok.ng, alcohol consumption or symptoms of GERD. Patients with BE had significantly longer esophageal acid exposure time in the supine position, measured by pH monitoring. CONCLUSION： The prevalence of BE in patients with GERD who were referred for endoscopy was 7.3%. BE seems to be associated with older age and more in patients with nocturnal gastroesophageal reflux.

关键词： Barrett's esophagus Gastrointestinal Endoscopy Gastroesophageal reflux Risk.factors

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Biomark.rs of Barrett's esophagus

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World Journal of Gastrointestinal Pathophysiology 2014年第4期5卷 450-456页

作者： Yasser Mahrous fouad Ibrahim Mostafa Reem Yehia hisham El-k.ayat Gastroenterology and Hepatology Unit Tropical Medicine Department Minia University Gastroenterology and Hepatology Department Theodore Research Institute

Barrett's esophagus is the strongest risk.for esophageal adenocarcinoma(EAC). Metaplasia in patients with BE may progress to dysplasia and then invasive carcinoma. Well-defined diagnostic, progressive, predictive, and prognostic biomark.rs are needed to identify the presence of the disease, estimate the risk.of malignant transformation, and predict the therapeutic outcome and survival of EAC patients. There are many predictive and prognostic mark.rs that lack.substantial validation, and do not allow stratification of patients with gastroesophageal reflux disease in clinical practice for outcome and effectiveness of therapy. In this short review we summarize the current k.owledge regarding possible biomark.rs, focusing on the pathophysiologic mechanisms to improve prognostic and therapeutic approaches.

关键词： Barrett’s esophagus Esophageal adenocarcinoma Biomark.rs

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