Design of closed loop for reproduction of gas-dominated hydrate flow.

The study presents a novel setup for measuring the flow regime of hydrate particles in a gas-dominated flow, which is of interest for applications such as natural gas transportation. A closed-flow loop, driven by a novel internal fan, enables continuous observation of hydrate particle behavior in a gas flow. The experimental setup allows the production and insertion of HFC134a gas hydrate particles with diameters of 10-50 µm into the gas flow loop via a bypass loop. The performance curve of the internal fan is validated, and its suitability for achieving the required flow speed (5 m/s) is demonstrated. Through an observation window using camera systems, the flow regime of glass beads is successfully visualized and analyzed. To validate the experimental data, a coupled computational fluid dynamics-discrete element method model is used to simulate the particle flow density distribution. The study findings demonstrate the effectiveness of the experimental setup in characterizing the flow regime of hydrate particles in a gas-dominated flow.

Microstructural investigation of morphology and kinetics of methane hydrate in the presence of tetrabutylammonium bromide: Insights for preservation and inhibition.

Developing highly efficient methane (CH4) hydrate storage methods and understanding the hydrate dissociation kinetics can contribute to advancing CH4 gas storage and transport. The effects of tetrabutylammonium bromide (TBAB) (a thermodynamic promoter) addition on the kinetics of CH4 hydrate were evaluated on the microscopic scale using synchrotron x-ray computed tomography (CT) and powder x-ray diffraction. Microscopic observations showed that a 5 wt. % TBAB solution facilitated the nucleation of CH4 hydrate owing to the initial growth of TBAB semi-clathrate hydrate particles. The CH4 hydrate crystals in the CH4 + TBAB hydrate sample were sponge-like with many internal pores and exhibited slightly enhanced self-preservation compared to the pure CH4 hydrate, both in the bulk and after pulverization to a fine powder. This study demonstrates the feasibility of controlling the rate of CH4 hydrate formation and preservation by using aqueous TBAB solutions in CH4 hydrate formation.

Isolation of microorganisms involved in reduction of crystalline iron(III) oxides in natural environments.

Reduction of crystalline Fe(III) oxides is one of the most important electron sinks for organic compound oxidation in natural environments. Yet the limited number of isolates makes it difficult to understand the physiology and ecological impact of the microorganisms involved. Here, two-stage cultivation was implemented to selectively enrich and isolate crystalline iron(III) oxide reducing microorganisms in soils and sediments. Firstly, iron reducers were enriched and other untargeted eutrophs were depleted by 2-years successive culture on a crystalline ferric iron oxide (i.e., goethite, lepidocrocite, hematite, or magnetite) as electron acceptor. Fifty-eight out of 136 incubation conditions allowed the continued existence of microorganisms as confirmed by PCR amplification. High-throughput Illumina sequencing and clone library analysis based on 16S rRNA genes revealed that the enrichment cultures on each of the ferric iron oxides contained bacteria belonging to the Deltaproteobacteria (mainly Geobacteraceae), followed by Firmicutes and Chloroflexi, which also comprised most of the operational taxonomic units (OTUs) identified. Venn diagrams indicated that the core OTUs enriched with all of the iron oxides were dominant in the Geobacteraceae while each type of iron oxides supplemented selectively enriched specific OTUs in the other phylogenetic groups. Secondly, 38 enrichment cultures including novel microorganisms were transferred to soluble-iron(III) containing media in order to stimulate the proliferation of the enriched iron reducers. Through extinction dilution-culture and single colony isolation, six strains within the Deltaproteobacteria were finally obtained; five strains belonged to the genus Geobacter and one strain to Pelobacter. The 16S rRNA genes of these isolates were 94.8-98.1% identical in sequence to cultured relatives. All the isolates were able to grow on acetate and ferric iron but their physiological characteristics differed considerably in terms of growth rate. Thus, the novel strategy allowed to enrich and isolate novel iron(III) reducers that were able to thrive by reducing crystalline ferric iron oxides.

Renal insufficiency is related to painless myocardial infarction.

BACKGROUND: Acute myocardial infarction (MI) sometimes occurs without painful symptoms and in such cases, prognosis is worsened by delays in diagnosis and revascularization. Renal insufficiency induces many types of neuropathy, but the relation between renal insufficiency and painless MI remains unclear. METHODS AND RESULTS: Patients with MI and elevated creatine kinase levels were retrospectively analyzed. Renal insufficiency (serum creatinine concentration > or =1.5 mg/dl) and other characteristics (age, sex, body mass index, hypertension, smoking, diabetes mellitus, dyslipidemia, history of stroke, previous MI, hemodialysis, and atrial fibrillation) were compared between patients who had MI with painful symptoms (painful MI, n=131) and patients who had MI without painful symptoms (painless MI, n=18). Other variables compared were the time from symptom onset to admission, peak creatine kinase concentration, Killip class, site of MI, emergency coronary angiography, postprocedural Thrombolysis In Myocardial Infarction grade III flow, and in-hospital death. Univariate analysis identified older age, renal insufficiency, and previous MI as predictors of painless MI. Patients with painless MI showed higher rates of Killip class > or =II and in-hospital death and a longer time from symptom onset to admission. However, multivariate analysis identified only renal insufficiency as an independent predictor of painless MI. CONCLUSIONS: MI without painful symptoms frequently develops in patients who have renal insufficiency, so the possibility of painless MI should be evaluated in such patients to ensure early diagnosis and treatment.

Paradoxical effect of eukaryotic expression vectors on reporters.

A critical issue in transfection or co-transfection experiments is to define the appropriate controls. In most cases, a corresponding empty vector is used as one control. We report a paradoxical effect of empty mammalian expression vectors on different reporters. We have found that different empty vectors can inhibit or stimulate the same reporter In addition, the same vector can have different effects on different reporters. This situation is further complicated by the observation that the effects of a vector on a reporter can vary depending on the cells used