Artificial Interference of Stress Field in a Near-Fracture show="" $6#?=""Zone by Water Injection in a Preexisting Crack

The in situ stress has an important influence on fracture propagation and fault stability in deep formation. However, the development of oil and gas resources can only be determined according to the existing state of in situ stress in most cases. It is passive acceptance of existing in situ stress. Unfortunately, in some cases, the in situ stress conditions are not conducive to resource development. If the in situ stress can be interfered in some ways, the stress can be adjusted to a more favorable state. In order to explore the method of artificial interference, this paper established the calculation method of the in situ stress around the cracks based on fracture mechanics at first and obtained the redistribution law of the in situ stress. Based on the obtained redistribution law, attempts were made to interfere with the surrounding in situ stress by water injection in the preexisting crack. On this basis, the artificial stress intervention was applied. The results show that artificial interference of stress can effectively be achieved by water injection in the fracture. And changing the fluid pressure in the crack is the most effective way. By stress artificial intervention, critical pressure for water channelling in fractured reservoirs, directional propagation of cracks in hydraulic fracturing, and stress adjustment on the structural plane were applied. This study provides guidance for artificial stress intervention in the exploitation of the underground resource.

ADIPOSE-DERIVED STEM CELL TRANSPLANTATION ON URETHRAL MICROVESSEL AND VOIDING FUNCTION

Objective: To examine the effects of adipose-derived stem cell (ADSC) transplantation on urethral tissue microvessel and voiding function on artificial stress urinary incontinence (SUI) in rats. Material & methods: 25 of 32 female wistar rats underwent vaginal distension as animal-SUI model. ADSCs were isolated from the peri-ovary fat, examined for stem cell properties, and labeled with PKH-2. Seven rats without vaginal distension and periurethral ADSCs injection as control. Twelve rats received periurethral injection of phosphate buffer saline as plasebo and 13 rats received periurethral injection of ADSCs. 14 and 28 days later, voided volume was meassured with voided stained on paper and microvessel density was meassured with immunohistochemical analysis (factor VIII R-Ag). Results: Voided volume analysis showed that rats in the plasebo group had abnormal voided volume compare to normal rats in day 14 (168.5 ± 119.05l vs 621.21 ± 283.85l; p < 0.05), and insignificant improvement of voided volume compare to normal rats in day 28 (852.09 ± 626.7l vs 868.49 ± 578.0l; p > 0.05). While in the ADSCs group only showed significant improvement of voided volume compare to abnormal rats in days 14 (379.35 ± 191.74l vs 228.18 ± 56.26l; p < 0.05). Immunohistochemical analysis showed that microvessel density higher in the ADSCs group compare to plasebo group in days 28 (12.86 ± 2.5 vs 9.50 ± 1.64; p < 0.05). Conclusion: ADSCs transplantation promotes improvements voided volume and urethral microvessel in the rat-SUI model. Keywords: Adipose-derived stem cell, vaginal distension, voided stained on paper, microvessel density.

Regulatory Role of Small Nucleolar RNAs in Human Diseases

Small nucleolar RNAs (snoRNAs) are appreciable players in gene expression regulation in human cells. The canonical function of box C/D and box H/ACA snoRNAs is posttranscriptional modification of ribosomal RNAs (rRNAs), namely, 2′-O-methylation and pseudouridylation, respectively. A series of independent studies demonstrated that snoRNAs, as well as other noncoding RNAs, serve as the source of various short regulatory RNAs. Some snoRNAs and their fragments can also participate in the regulation of alternative splicing and posttranscriptional modification of mRNA. Alterations in snoRNA expression in human cells can affect numerous vital cellular processes. SnoRNA level in human cells, blood serum, and plasma presents a promising target for diagnostics and treatment of human pathologies. Here we discuss the relation between snoRNAs and oncological, neurodegenerative, and viral diseases and also describe changes in snoRNA level in response to artificial stress and some drugs.

Generalized FVDAM Theory for Periodic Materials Undergoing Finite Deformations—Part I: Framework

The recently constructed generalized finite-volume theory for two-dimensional linear elasticity problems on rectangular domains is further extended to make possible simulation of periodic materials with complex microstructures undergoing finite deformations. This is accomplished by embedding the generalized finite-volume theory with newly incorporated finite-deformation features into the 0th order homogenization framework, and introducing parametric mapping to enable efficient mimicking of complex microstructural details without artificial stress concentrations by stepwise approximation of curved surfaces separating adjacent phases. The higher-order displacement field representation within subvolumes of the discretized unit cell microstructure, expressed in terms of elasticity-based surface-averaged kinematic variables, substantially improves interfacial conformability and pointwise traction and nontraction stress continuity between adjacent subvolumes. These features enable application of much larger deformations in comparison with the standard finite-volume direct averaging micromechanics (FVDAM) theory developed for finite-deformation applications by minimizing interfacial interpenetrations through additional kinematic constraints. The theory is constructed in a manner which facilitates systematic specialization through reductions to lower-order versions with the 0th order corresponding to the standard FVDAM theory. Part I presents the theoretical framework. Comparison of predictions by the generalized FVDAM theory with its predecessor, analytical and finite-element results in Part II illustrates the proposed theory's superiority in applications involving very large deformations.