Effect of Coal Particle Size on the Kinetics of Gas Hydrate Formation.

Coal and gas outbursts are one of the main factors that restrict access to high-quality coal, and the adoption of gas hydration solidification technology is expected to reduce the chance of such accidents. In this study, experiments were conducted on the kinetics of CH4 and CO2 hydrate formation in four coal particle size systems (C1:0.425-0.850 mm, C2:0.250-0.425 mm, C3:0.180-0.250 mm, and C4:0.150-0.180 mm). An experimental apparatus for high-pressure visualization of gas hydrate generation was used to obtain kinetic parameters such as gas consumption and the average growth rate during hydrate formation. The results showed that gas consumption and average growth rate of CO2 hydrate decreased with decreasing coal grain size, while gas consumption and average growth rate of CH4 hydrate decreased and then increased slightly with decreasing coal grain size, indicating that larger coal grains were beneficial to hydrate formation within a certain particle size range. The results of this research study are expected to provide an experimental reference for the development and application of technology for the solidification of gas hydrates to limit surges.

Raman Spectroscopy Study on Ternary Model Coal Mine Methane Hydrates.

The microfeatures of coal mine methane (CMM) hydrates, synthesized with three gas samples (CH4/C2H6/N2, G1 = 43 : 47 : 10, G2 = 60 : 30 : 10, and G3 = 74 : 16 : 10) in a self-made transparent high-pressure cell at 275.15 K and 5 MPa were investigated using Raman spectroscopy. As a discriminator, the vibrational band frequencies in the C-C regions of the recorded hydrate Raman spectra for C2H6 show that G1∼G3 hydrates are structure I. The three principal parameters used to study the microfeatures of the model CMM hydrates, including cavity occupancies, hydrate guest compositions, and hydration numbers, were calculated. The large cavity occupancies for C2H6 constantly decrease from 85.12 to 79.32%, while the small cavity occupancies for CH4 have a continuous increase from 73.75 to 96.42%. However, CH4 competes with C2H6 on entering the large cavities for their large cavity occupancies of 12.79-17.31%. The cavity occupancies of N2 are less than 1.2%. The hydrate composition calculations show that the molar fractions of C2H6 are the maximum. The hydration numbers range from 6.221 to 6.00. Based on the hydrate guest compositions and hydration numbers, the molecular formulas of the three CMM hydrates are presented.

Kinetics of Hydrate Formation and Dissociation in Coal at Different Temperatures Based on Impedance Method.

In the process of coal mining, gas outburst is a challenge that must be prevented to guarantee mining safety. Forming gas hydrate in coal can reduce the original gas pressure and delay the concentrative outbursts of gas flow, which is one of the potential technologies to prevent gas outbursts in coal. In this work, we perform the formation and dissociation kinetics experiment of hydrate in the presence of coal and tetrahydrofuran (THF) at the temperature based on different geological conditions in China by means of the experimental device with the impedance measurement function. The results showed that the impedance change can qualitatively describe the kinetic characteristics of hydrate formation and dissociation in coal. The sudden change in pressure and system impedance during gas hydrate formation indicated the nucleation point at which hydrate formation started, by which the induction time can be acquired. Pressure and impedance suddenly changed at the same time, which implied that methane molecules and tetrahydrofuran (THF) molecules entered the hydrate phase at the same time. When the dissociation temperature increased to 303.15 K, the hydrate dissociation rate can be less affected by dissociation temperature if it continued to increase. This work highlights that gas hydrate formation in coal can effectively prevent gas outbursts.

Combination of mesenchymal stem cell injection with icariin for the treatment of diabetes-associated erectile dysfunction.

The present study was aimed to examine whether icariin, a traditional Chinese medicine, could improve therapeutic effects of adipose derived mesenchymal stem cells (ADSCs) for diabetes-associated erectile dysfunction (DMED). DMED were induced in rats by intraperitoneal injection of streptozotocin and confirmed by erectile function measurement. Then, rats of diabetic ED were randomly divided to receive the treatment of saline, ADSCs, icariin or ADSCs combined with icariin respectively. Compared with the treatment by ADSCs or icariin alone, intracavernosum injection of ADSCs combined with the following daily gastric gavage of icariin significantly augmented the value of ICP and ICP/MAP (p<0.01). Meanwhile, the survival of transplanted ADSCs was much improved due to the application of icariin. Similarly, immunofluorescent staining analysis demonstrated that the improved erectile tissue structure by combination of ADSCs and icariin was significantly associated with the increased expression of endothelial markers (vWF) (p<0.01) and smooth muscle markers (α-SMA) (p<0.01). Furthermore, the structure changes in corpus cavernosum were further confirmed by the Masson's trichrome staining. To explore the possible mechanism underlying icariin-enhanced therapeutic efficacy of MSCs, we employed an in vitro testing system by introducing H2O2 to imitate oxidative stress condition considering the oxidative environment faced by engrafted ADSCs and anti-oxidative capacity of icariin. In vitro, we found that the addition of icariin considerably reduced the apoptosis of ADSCs, and attenuated the intracellular reactive oxygen species (ROS), the superoxidase dismutase (SOD) activity and the lactate dehydrogenase (LDH). Subsequently, we examined the expression of apoptosis-related proteins and explored the potential signaling pathway through which icariin promoted the survival of ADSCs against oxidative stress. It was demonstrated that icariin significantly inhibited the upregulation of apoptosis-related proteins under oxidative condition, including Bax and cleaved caspase-3, while promoted the expression of anti-apoptotic factor BCL2. These effects were accompanied with the activation of signal molecules, PI3K/Akt and STAT3. The further signal protein inhibition assays exhibited that the suppression of STAT3 abrogated the icariin-mediated anti-apoptotic effects observed above, while did not influence the expression of PI3K/Akt. However, PI3K inhibition could abrogate icariin-mediated STAT3 activation and achieved a similar effect as STAT3 inhibition. Our results suggested that icariin was an effective adjuvant for enhancing ADSC-based therapy of DMEM, which may be ascribed to their protection of ADSCs against oxidative stress via the regulation of PI3K/Akt-STAT3 signal pathway.

Multi-locus Test and Correction for Confounding Effects in Genome-Wide Association Studies.

Genome-wide association studies (GWAS) examine a large number of genetic variants, e. g., single nucleotide polymorphisms (SNP), and associate them with a disease of interest. Traditional statistical methods for GWASs can produce spurious associations, due to limited information from individual SNPs and confounding effects. This paper develops two statistical methods to enhance data analysis of GWASs. The first is a multiple-SNP association test, which is a weighted chi-square test derived for big contingency tables. The test assesses combinatorial effects of multiple SNPs and improves conventional methods of single SNP analysis. The second is a method that corrects for confounding effects, which may come from population stratification as well as other ambiguous (unknown) factors. The proposed method identifies a latent confounding factor, using a profile of whole genome SNPs, and eliminates confounding effects through matching or stratified statistical analysis. Simulations and a GWAS of rheumatoid arthritis demonstrate that the proposed methods dramatically remove the number of significant tests, or false positives, and outperforms other available methods.

Impact of obesity upon prostate cancer-associated mortality: A meta-analysis of 17 cohort studies.

A number of epidemiological studies have suggested that obesity is associated, albeit inconsistently, with the incidence of prostate cancer (PCa). In order to provide a quantitative assessment of this association, the present study examined the correlation between obesity and the incidence and associated mortalities of PCa in an updated meta-analysis of cohort studies. The cohort studies were identified by searching the EMBASE and MEDLINE databases on January 1, 2014. The summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated using random-effects models. In total, 17 studies, which included 3,569,926 individuals overall, were selected according to predefined inclusion criteria. Based upon the results of the random-effects models, obesity was not significantly correlated with the incidence of PCa (RR, 1.00; 95% CI, 0.95-1.06). However, further analysis revealed that obesity was significantly correlated with an increased risk of aggressive PCa (RR, 1.14; 95% CI, 1.04-1.25). Furthermore, an increased risk of PCa-associated mortality was significantly associated with obesity (RR, 1.24; 95% CI, 1.15-2.33), without any heterogeneity between the studies (I2=0.0%; P=0.847). The present study provides preliminary evidence to demonstrate that obesity is a significant risk factor for aggressive PCa and PCa-specific mortality. The low survival rates observed among obese males with PCa may be a likely explanation for this association.

[Raman spectroscopic studies on CO2-CH4-N2 mixed-gas hydrate system].

Accurate determination of coal mine gas separation product characteristics is the key for gas separation application based on hydrate technology. Gas hydrate was synthesized from two types of gas compositions (CO2-CH4-N2). The separation products were measured by in situ Raman spectroscopy. The crystal structure of mixed-gas hydrate was determined, and the cavity occupancy and hydration index were calculated, based on the object molecular various vibrational mode, "loose cage-tight cage" model and the Raman bands area ratio, combined with the model of van der Waals-Platteeuw. The results show that the mixed-gas hydrates are both structure I for the two gas samples; Large cages of mixed-gas hydrate are nearly occupied by guest molecules, and the large cavity occupancies are 98.57% and 98.52%, respectively; but small cages are not easy to be occupied, and the small cavity occupancies are 29.93% and 33.87%, respectively; hydration index of the two gas samples hydrate is 7.14 and 6.98, respectively, which is greater than the theoretical value of structure I.