The rational mine support system designs for underground excavations in backfill are discussed. The current mine support technology applied in excavations in backfill in Artemievsk and Orlovsky mines ...is examined. The strength and deformation characteristics of backfill samples are tested on a laboratory scale. The FEM-based stress–strain analysis of ore body and backfill is described with the assessment of their stability. The probable failure zones in backfill and ore body during to-downward slice mining are determined. The rational support design is validated for backfill having stability category I, II and III. The pilot test data on the load-bearing capacity of friction-anchored rock bolts in backfill are assessed. The economic efficiency of the mixed-type support composed of steel frame and friction-anchored rock bolts in backfill is demonstrated.
The state of mining in Artemevsk Mine is analyzed, and the current and recommendable support designs are described. In unstable rock mass, it is possible to replace heavy and laborious steel frame ...support by less expensive and lower labor-intensive shotcrete lining with surface reinforcement without reduction in load-bearing capacity of the support. The variants of arrangement of shotcrete production plant are discussed, and the economic efficiency of the proposed wet-mix shotcreting is calculated in terms of Artemevsk Mine.
Abstract
Introduction
According to the current guidelines the visualization of atherosclerotic plaques in the carotid arteries is the only option that carotid ultrasound provides for the assessment ...of cardiovascular risk (CVR). The direction devoted to the development and implementation of markers based on the quantification of atheroma, is promising.
Purpose
The aim of the study was to evaluate the prognostic value of various markers of carotid atherosclerosis (plaque, carotid total plaque area (cTPA) and carotid stenosis) in patients at high and very high CVR.
Methods
The study included patients aged 40–75 years at high and very high CVR. All patients underwent carotid duplex ultrasound. The presence of carotid plaque was assessed according to Mannheim consensus. The percentage of stenosis was measured planimetrically in the B-mode by the diameter in the cross section of the vessel.
cTPA was estimated in the longitudinal position, which allows to achieve the best visualization of plaque, the area of plaque was measured in the manual trace mode. These measurements were performed for each rendered plaque, followed by the calculation of the total value.
The combined endpoint was cardiovascular death, non-fatal myocardial infarction or unstable angina (which required hospitalization), non-fatal stroke, and coronary revascularization.
Results
The study included 100 patients at high and very high risk. The duration of the follow-up period was 24.4 (14.1–34.3) months. The events constituting the combined endpoint occurred in 34 (34%) patients: cardiovascular death was recorded in 7 (7%) patients; non-fatal myocardial infarction or stroke in 3 (3%) patients; unstable angina, which required hospitalization in 24 (24%) patients, while emergency coronary angiography was performed in 8 (8%) patients, coronary artery stenting was performed in 3 (3%) cases.
The presence of carotid plaque in accordance with Cox regression after adjusting for factors such as sex, age, smoking, hypertension, BMI, eGFR, LDL-c and HbA1c, RR of adverse cardiovascular events was 10.5 (95% CI 1.27–86.5; p=0.008; see Figure 1).
The optimal cut-off values of cTPA and carotid stenosis were determined by ROC-analysis.
An increase in cTPA ≥69 mm2 corrected for sex, age, smoking, hypertension, BMI, eGFR, LDL-c, HbA1c, and the presence of carotid plaque was associated with an increase in the RR of adverse cardiovascular events by 5.86 times (95% CI 2.09–16.4; p=0.001; see Figure 1).
Also, there were no statistically significant associations between carotid arteries stenosis and adverse cardiovascular events (RR 1.29; 95% CI 0.61–2.76; p=0.504).
Kaplan–Meier curves for cTPA, stenosis
Conclusion
In patients at high and very high cardiovascular risk among carotid ultrasound parameters the presence of carotid plaque and cTPA, but not the degree of stenosis, had an independent predictive value regarding the development of adverse cardiovascular events.
The article provides an overview of current views on the role of biomechanical forces in the pathogenesis of atherosclerosis. The importance of biomechanical forces in maintaining vascular ...homeostasis is considered. We provide descriptions of mechanosensing and mechanotransduction. The roles of wall shear stress and circumferential wall stress in the initiation, progression and destabilization of atherosclerotic plaque are described. The data on the possibilities of assessing biomechanical factors in clinical practice and the clinical significance of this approach are presented. The article concludes with a discussion on current therapeutic approaches based on the modulation of biomechanical forces.
Abstract
New socio-economic conditions for the development of Russia dictate new requirements for the protection of buildings, equipment and personnel of various facilities from fires and their ...consequences. In complex fire extinguishing systems, the timeliness of fire detection and the effectiveness of extinguishing is the key to preserving material values and human lives. An urgent task is not only the improvement of existing fire extinguishing systems, but also the development of new systems, the basis of which is based on previously unused approaches. These approaches are based both on the previously known physical and chemical methods of extinguishing fires, and on the methods being investigated and studied at present. One of the promising methods of extinguishing fires is the technology of extinguishing fires using the effect of an electromagnetic field on the diffusion flame. The study of this method involves the analysis of physical processes that are electromagnetic in nature of interaction occurring in the system “diffusion flame torch - electromagnetic wave”. In this work, a quantitative analysis of the parameters affecting the possible mechanisms of interaction of the elements of this system is carried out. A mathematical model of the considered physical processes is presented.
Abstract
Background
The role of NK-cells and NKT-cells and their subtypes at various stages of the development of atherosclerosis is poorly understood. It was previously shown that CD3+CD56+CD8+ ...cells can secrete pro-inflammatory cytokines and an increase in their number has been established in patients with active Behçet's Disease and Multiple Sclerosis.
Purpose
To study the relationship between the number of activated CD3+CD56+CD8+ cells and the echogenicity of plaques in patients with carotid atherosclerosis.
Methods
The study included 40 patients, 21 (52.5%) men and 19 (47.5%) women who underwent carotid ultrasound and immunological studies. The median age was 53.5 (46.7; 57.0) years. All patients underwent duplex ultrasound scanning of the carotid arteries. If an atherosclerotic plaque was detected, its image was saved and exported to Adobe Photoshop CS6® followed by analysis of the gray-scale median (GSM) of the plaque. Hypoechoic was considered a carotid plaque whose GSM values were less than 50. The number of CD3+CD56+CD8+CD11b+ cells was evaluated by flow cytometry using a flow cytometer.
Results
Among the examined patients, carotid plaques were detected in 31 (77.5%) participants. The average values of GSM visualized plaques were 58.0 (46.0; 71.5). Atherosclerotic plaques with GSM <50 were detected in 11 (35.5%) patients.
In patients with hypoechoic carotid plaques, the number of CD3+CD56+CD8+CD11b+ cells was statistically significantly higher – 352 (55.0; 505) cells/uL versus 66.0 (15.5; 138) cells/uL in patients with plaques whose GSM values were more than 50 (p=0.020). Based on the results of correlation analysis it was established inverse relationship between number of CD3+CD56+CD8+CD11b+ cells and GSM of plaques (r=−0.427; p=0.016). According to the results of the ROC-analysis, an increase in the number of activated NKT-CD8+ cells over 46.5 cells/uL was a predictor of the presence of hypoechogenic carotid plaques with a sensitivity of 81.8% and a specificity of 45.0% (see Figure 1).
Conclusion
In patients with hypoechoic carotid plaques, the number of CD3+CD56+CD8+CD11b+ cells was significantly higher in comparison with other patients. An increase in the number of activated NKT-CD8+ cells over 46.5 cells/uL was a predictor of the presence of hypoechoic carotid plaques with sensitivity of 81.8% and specificity of 45.0%
Figure 1
Funding Acknowledgement
Type of funding source: None
The problem connected with the mine support with metal frames in unstable rock mass subjected to stoping is analyzed. In terms of the complicated geological conditions of the Orlov mine (East ...Kazakhstan), the application of Blok-Fil phenol resin in filling voids and domes after rock falls in the gap between the metal frames and roof is tested at the laboratory and pilot scale. It is found that owing to complete filling of voids with resin, no dynamic loads on the support due to rock falls and self-heating of ore and mine air are observed.
Goal. Metal frame supports SVP-22 with round timber lagging and backfilling of the voidsof unsupported space with chock support is used in the workings of unstable ores and rocks at the Orlovsky ...mine. When filling the voids with a chock supportmanually, people are located in an unsupported part of the working, therefore this operation is hazardous and laborious. The purpose of the work is to select and test the backfill material for voids of unsupported space, which ensures a decrease in diffusion and oxygen seepage to the centers of spontaneous ignition of the ore bodies under conditions of intense oxidation of sulphide ores at the Orlovsky deposit. Methods. Foaming non-combustible materials (“Blockfil” phenolic two-component resins) were tested in the experimental works at the Orlovsky mine for backfilling the voids when supporting the mine workings by metal frame supports with a round timber lagging. Results. It has been established that the use of phenolic resins as backfilling will reduce the intensity of the oxidation reaction and prevent self-heating of the ore to critical temperatures, and also prevent or slow down the process of heating ofmine air from the heated surface of the ore body to temperatures exceeding the design values. Conclusions. The use of phenolic resin “Blockfil” to fill the voids ensured the absence of deformation of the elements of the metal frame support and the safety of mining, and also allowed to reduce the intensity of the oxidation reaction and prevent self-heating from the ore to critical temperatures and prevent or slow down the process of heating the mine air from the heated surface of the ore body to temperatures, exceeding the design values.
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