Dissociation characteristics and anthropogenic emissions from the combustion of double gas hydrates.

Gas hydrates are an alternative and environmentally friendly energy source increasingly in the focus of scientific attention. The physicochemical processes behind gas hydrate combustion are studied experimentally and numerically with a view to improving the combustion efficiency and reducing gas emissions. It is important to estimate the pollutant emission concentrations in the context of combustion conditions. The research deals with the dissociation and combustion behavior of double gas hydrates in a tubular muffle furnace. Gas hydrates of different composition are considered: methane, methane-ethane, methane-propane and methane-isopropanol. Double gas hydrates are characterized by more stable combustion compared to methane hydrate. It is also shown that the double gas hydrate dissociation rate increases by 15-30% with increasing temperature. Dissociation and combustion processes were also modeled as part of the research, accounting for phase transitions in a gas hydrate layer. According to the simulation results, the total dissociation rate of gas hydrate increases by 3 times with an about 2.5-times increase in the powder layer thickness. Our experiments also focused on the impact of furnace temperature and gas hydrate composition on concentrations of anthropogenic gas emissions. We have found that the presence of heavy hydrocarbons such as ethane, propane and isopropanol in double gas hydrates reduce unburned CH4 emissions by 60%. Also, an increase in the combustion efficiency of double gas hydrates, accompanied by a decrease in the concentrations of unburned CH4 and CO, affects the yield of CO2, which increased by 13-35%. When we increased the temperature in the furnace from 750 °C to 1050 °C, concentrations of nitrogen oxides and carbon dioxide increased by up to five times. Thus, the resulting correlations between the key parameters of these processes and a set of the main inputs illustrate the possibility to predict the optimal conditions for the combustion of gas hydrates.

[Aggressive role of lysosomal enzymes in gastric ulceration]. / Agressivnaia rol' lizosomnykh fermentov pri iazvoobrazovanii v zheludke.

Administration of lysosomes and lysosome enzymes into the submucous base of intact rats' stomachs did not result in ulceration. Premedication by histamine, serotonin (combined and separated) and ACTH did not increase sensibility of mucous membrane to lysosome enzymes. Prednisolone-premedication provoked the decrease of mucous membrane resistance to free lysosome enzymes and appearance of ulcerative lesions in the point of enzyme applications. Free lysosome enzymes are able to produce ulcerative lesions. This process is going on with the participation of prednisolone.

[Proteolytic enzymes of the gastric mucosa in the dog]. / Proteoliticheskie fermenty slizistoi zheludka u sobak.

12 proteolytic fractions were obtained with disc--electrophoresis from the gastric mucosa in healthy dogs. 5 proteases (I group) were only found in fundus and gastric body whereas 7 those (II group) were found in antrum as well. Study of the fractions proteolytic activity revealed two of them to be active in pH 1.0-5.0; two in pH 4.0-5.0; one in pH 1.0-2.0; the area of other proteases activity involved 3-4 units of pH. The considerable amount of proteases and the large area of their activity seem to secure the protein hydrolysis in the stomach in different pH values of eaten food.

[Spectrum of acid proteases in the gastric juice of dogs in the normal state and in experimental atophan-induced stomach ulcer]. / Spektr kislykh proteaz zheludochnogo soka sobak v norme i pri éksperimental'noi atofanovoi iazve zheludka.

Study of the spectrum of acid proteases of dog gastric juice secreted in response to different stimuli in health and atophan gastric ulcer has shown that gastric juice may contain up to 17 proteases as evaluated from relative electrophoretic mobility of protease fractions. In individually taken gastric juice samples, there occur 4-17 or mostly about 7-9 proteases, depending on the stimulus. During ulcer formation, the incidence pattern of proteases that are secreted in response to all the stimuli noticeably deviates from normal. However, the most demonstrable alterations occur as a result of histamine administration, manifesting in the emergence of 4 fractions undetectable in health and increased secretion of the remaining proteases. Apparently, ulcer formation is accompanied by disturbance of the mechanisms that control the secretion of proteases of gastric juice, especially after histamine administration.

[Stressfulness of gastric juice]. / K voprosu ob agressivnosti zheludochnogo soka.

A comparative analysis was made of the aggressive properties of gastric juice secreted by normal people and those suffering from peptic ulcer in response to histamine and pentagastrin. Ulcerogenic activity of gastric juice obtained in response to histamine was shown to increase in peptic ulcer. The "pentagastrin" juice did not exhibit such an effect. Experimental study of the occurrence of gastric juice proteases in dogs revealed an increased occurrence in most proteases and their elevated number of the "histamine" juice in ulcer development and a decreased occurrence of proteases in the "pentagastrin" juice. Low aggressiveness of gastric juice from peptic ulcer patients during pentagastrin-induced stimulation of secretion appears to be related to the listed changes in the spectrum and occurrence of proteases.

[Quantitative changes in gastric juice proteases in dogs during ulcer formation in the stomach]. / Kolichestvennye izmeneniia proteaz zheludochnogo soka sobak pri iazvoobrazovanii v zheludke

Disc-electrophoretic investigation of proteases of the gastric juice of dogs under normal conditions and in experimental atophan ulcer of the stomach demonstrated that in fasting dogs ulceration was accompanied by marked quantitative changes in the protease spectrum. Fraction No. 6 showed a significant elevation against the background of total reduction of proteolytic fraction of the gastric juice in sham feeding of ulcerated dogs. Sham feeding replete ulcerated dogs indicated a marked increase of fractions No.1 and No.2. The noted changes of the gastric juice protease spectrum may be of ulcerogenic significance.