Study on the rheological properties of barite-free drilling mud with high density

Improved drilling and reservoir penetration efficiency is directly related to the quality of the drilling mud used. The right choice of mud type and its components will preserve formation productivity, stability of the well walls and reduce the probability of other complications. Oil and gas operators use barite, less often siderite or hematite weighting agent as a weighting component in the composition of drilling muds for the conditions of increased pressure. But the use of these additives for the penetration of the productive formation leads to the reduction of filtration characteristics of the reservoir, as it is almost impossible to remove them from the pore channels. Therefore, barite-free drilling mud of increased density based on formic acid salts with the addition of carbonate weighting agent as an acid-soluble bridging agent is proposed. The results of experimental investigations on rheological parameters of barite-free solutions are given and the obtained data are analyzed. Based on the comparison of results it is recommended to use high-density drilling mud on the basis of formic acid salts (sodium and potassium formate) and with the addition of partially hydrolyzed polyacrylamide with molecular mass of 27 million

Continuous Synthesis of Hydrogenated Graphene in Thermal Plasma

© 2018, Pleiades Publishing, Ltd. A single-stage catalyst free synthesis of hydrogenated graphene was studied in the process of methane conversion in a helium plasma jet created by a plasma torch at the power up to 45 kW and the pressure of 710 Torr. The synthesis products were studied by the methods of scanning and transmission electron microscopy, thermal analysis, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analysis

All electron and pseudopotential study of the spin polarization of the V (001) surface: LDA versus GGA

The spin-polarization at the V(001) surface has been studied by using different local (LSDA) and semilocal (GGA) approximations to the exchange-correlation potential of DFT within two ab initio methods: the all-electron TB-LMTO-ASA and the pseudopotential LCAO code SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms). A comparative analysis is performed first for the bulk and then for a N-layer V(001) film (7 < N < 15). The LSDA approximation leads to a non magnetic V(001) surface with both theoretical models in agreement (disagreement) with magneto-optical Kerr (electron-capture spectroscopy) experiments. The GGA within the pseudopotential method needs thicker slabs than the LSDA to yield zero moment at the central layer, giving a high surface magnetization (1.70 Bohr magnetons), in contrast with the non magnetic solution obtained by means of the all-electron code.Comment: 12 pages, 1 figure. Latex gzipped tar fil

Screening and Early Diagnosis of Hepatocellular Cancer and Optimization of Diagnostic Imaging Techniques: A Review and Conclusion of the Expert Panel

Аim: to describe modern approaches for screening and early diagnosis of hepatocellular carcinoma (HCC).Key points. Screening for HCC in high-risk groups (cirrhosis of any etiology, patients with chronic viral hepatitis B and patients with F3 liver fibrosis) should be organized as regular (every 6 months) liver ultrasound in combination with determination of the serum alpha-fetoprotein (AFP) level. At an AFP level of ≥ 20 ng/ml, even in the absence of changes according to ultrasound data, it is advisable to perform MRI with a hepatospecific contrast agent (gadoxetic acid) which makes it possible to detect very small focal liver lesions. If focal liver lesions of 1–2 cm are detected on ultrasound, additional imaging of the liver using MRI with a hepatospecific contrast agent gadoxetic acid helps to identify HCC at an earlier stage or high degree dysplastic nodes. When planning surgical treatment and liver transplantation, it is preferable to use MRI with a hepatospecific contrast agent, since the presence of the hepatobiliary phase may allow the detection of additional smaller focal liver lesions and assess the nature of the focal liver lesion. When a patient is included in the waiting list for liver transplantation, the optimal frequency of liver MRI is 1 time in 3 months.Conclusion. MRI with hepatospecific contrast agent gadoxetic acid is effective in screening, early diagnosis and treatment planning for HCC

Portal Vein Embolization is Associated with Reduced Liver Failure and Mortality in High-Risk Resections for Perihilar Cholangiocarcinoma

Background Preoperative portal vein embolization (PVE) is frequently used to improve future liver remnant volume (FLRV) and to reduce the risk of liver failure after major liver resection. Objective This paper aimed to assess postoperative outcomes after PVE and resection for suspected perihilar cholangiocarcinoma (PHC) in an international, multicentric cohort. Methods Patients undergoing resection for suspected PHC across 20 centers worldwide, from the year 2000, were included. Liver failure, biliary leakage, and hemorrhage were classified according to the respective International Study Group of Liver Surgery criteria. Using propensity scoring, two equal cohorts were generated using matching parameters, i.e. age, sex, American Society of Anesthesiologists classification, jaundice, type of biliary drainage, baseline FLRV, resection type, and portal vein resection. Results A total of 1667 patients were treated for suspected PHC during the study period. In 298 patients who underwent preoperative PVE, the overall incidence of liver failure and 90-day mortality was 27% and 18%, respectively, as opposed to 14% and 12%, respectively, in patients without PVE (p &lt; 0.001 and p = 0.005). After propensity score matching, 98 patients were enrolled in each cohort, resulting in similar baseline and operative characteristics. Liver failure was lower in the PVE group (8% vs. 36%, p &lt; 0.001), as was biliary leakage (10% vs. 35%, p &lt; 0.01), intra-abdominal abscesses (19% vs. 34%, p = 0.01), and 90-day mortality (7% vs. 18%, p = 0.03). Conclusion PVE before major liver resection for PHC is associated with a lower incidence of liver failure, biliary leakage, abscess formation, and mortality. These results demonstrate the importance of PVE as an integral component in the surgical treatment of PHC

ПЕРВЫЕ РЕЗУЛЬТАТЫ РАДИКАЛЬНЫХ И УСЛОВНО РАДИКАЛЬНЫХ РЕЗЕКЦИЙ ПРИ ОПУХОЛИ КЛАЦКИНА

Relevance: Hilar cholangiocarcinoma is the most common malignant tumor of the bile ducts.Aim: analysis of the first experience of radical and conditionally radical operations performed in MCSC during one year.Materials and methods: Extended hepatectomies combined with resection of bile ducts and first segment performed in 18 patients with Klatskin tumor. Right hemihepatectomy performed in 8 patients, resection with caudal lobectomy – in 8 patients. The preoperative percutaneous right-sided selective portal embolisation using Celonova microspheres was performed in 5 patients. One patient with type II tumor according to Bismuth-Corlette classification underwent hemihepatectomy with a left caudal lobectomy and resection of the extrahepatic bile ducts using laparoscopic approach and DaVinci robotic system.Results: The average volume of intraoperative blood loss was 705±616 ml (range 200 to 2000 ml). Postoperative III and IV grade complications according to Clavien-Dindo classification occurred in 13 patients (72%). Two patients (11%) died postoperatively. The cause of death in both observations was severe sepsis. Patients with R1 and R2-resections undergo adjuvant chemotherapy with no objective signs of progression. Patients with R0-resection are under observation with no signs of progression.Conclusion: Late diagnosis, a high risk of postoperative complications requires a multidisciplinary approach at each stage of the treatment of Klatskin tumor.Актуальность. Воротная холангиокарцинома является наиболее частой из злокачественных опухолей желчных протоков.Цель. Анализ первого опыта радикальных и условно радикальных операций, выполненных в МКНЦ в течение года.Материал и методы. Обширные резекции печени в сочетании с резекцией протоков и первого сегмента выполнены 18 пациентам с опухолью Клацкина. Правосторонняя гемигепатэктомия выполнена 8 пациентам, резекция с каудальной лобэктомией  — 8 пациентам. В предоперационном периоде правосторонняя чрескожная селективная портальная эмболизация микросферами Celonova выполнена 5 пациентам. Одному пациенту со II типом опухоли по Bismuth-Corlette левосторонняя гемигепатэктомия с каудальной лобэктомией и резекцией внепеченочных желчных протоков выполнена лапароскопическим доступом с использованием роботизированного комплекса DaVinci.Результаты. Средний объем интраоперационной кровопотери составил 705±616 мл (200–2000 мл). Послеоперационные осложнения III и V типов согласно классификации послеоперационных осложнений Clavien-Dindo имели место у 13 пациентов (72%). На госпитальном этапе умерло 2 пациента (11%). Причиной летального исхода в обоих наблюдениях явился тяжелый сепсис. Пациентам, оперированным в объеме R1 и R2, проводится химиотерапевтическое лечение. Убедительных данных за прогрессирование заболевания нет. Пациенты, оперированные в объеме R0, находятся под наблюдением без признаков прогрессии.Заключение. Поздняя диагностика, высокий риск осложнений хирургического лечения опухоли Клацкина требует мультидисциплинарного подхода на каждом из этапов лечения. Относительно медленное прогрессирование опухоли по сравнению с другими холангиокарциномами оправдывает агрессивную хирургическую тактику и целесообразность адъювантной химиотерапии при R1, R2 резекциях. Лучшие результаты лечения обеспечивает резекция в объеме R0

The Russian consensus on the diagnosis and treatment of chronic pancreatitis: Enzyme replacement therapy

The Russian consensus on the diagnosis and treatment of chronic pancreatitis has been prepared on the initiative of the Russian Pancreatology Club to clarify and consolidate the opinions of Russian specialists (gastroenterologists, surgeons, and pediatricians) on the most significant problems of diagnosis and treatment of chronic pancreatitis. This article continues a series of publications explaining the most significant interdisciplinary consensus statements and deals with enzyme replacement therapy