Establishing the Relationship between Cutting Speed and Output Parameters in Belt Grinding on Steels,Aluminum and Nickel Alloys: Development of Recommendations

This paper presents the research results of one of the main technological parameters of belt grinding, i.e., the cutting speed while machining corrosion- and heat-resistant, structural carbon and structural alloy steels, aluminum, and heat-resistant nickel alloys. Experimental and analytical methods are used to establish the dependence of the output parameters of surface belt grinding on the cutting speed and tool characteristics. An analytical model, considering the physical and mechanical properties of the grinding belt (strength depending on the base and bond; the thermal conductivity; the type of grinding operation) and the machined material, is created to determine the belt grinding speed. The output parameters, such as the arithmetic mean of the surface roughness (Ra) and the material removal rate (MRR) during the belt grinding of steels, heat-resistant and light alloys, have been studied. Based on the empirical dependencies of the belt grinding parameters, the model was developed for the selection and setting of the cutting speed of belt grinding for the aforementioned alloys, taking into account the type of operation, the type of the machined material, and the main characteristics of the sanding belt.     

Surface Roughness Evaluation in Thin EN AW-6086-T6 Alloy Plates after Face Milling Process with Different Strategies

Lightweight alloys made from aluminium are used to manufacture cars, trains and planes. The main parts most often manufactured from thin sheets requiring the use of milling in the manufacturing process are front panels for control systems, housing parts for electrical and electronic components. As a result of the final phase of the manufacturing process, cold rolling, residual stresses remain in the surface layers, which can influence the cutting processes carried out on these materials. The main aim of this study was to verify whether the strategy of removing the outer material layers of aluminium alloy sheets affects the surface roughness after the face milling process. EN AW-6082-T6 aluminium alloy thin plates with three different thicknesses and with two directions relative to the cold rolling process direction (longitudinal and transverse) were analysed. Three different strategies for removing the outer layers of the material by face milling were considered. Noticeable differences in surface roughness 2D and 3D parameters were found among all machining strategies and for both rolling directions, but these differences were not statistically significant. The lowest values of Ra = 0.34 µm were measured for the S#3 strategy, which asymmetrically removed material from both sides of the plate (main and back), for an 8-mm-thick plate in the transverse rolling direction. The highest values of Ra = 0.48 µm were measured for a 6-mm-thick plate milled with the S#2 strategy, which symmetrically removed material from both sides of the plate, in the longitudinal rolling direction. However, the position of the face cutter axis during the machining process was observed to have a significant effect on the surface roughness. A higher surface roughness was measured in the areas of the tool point transition from the up-milling direction to the down-milling direction (tool axis path) for all analysed strategies (Ra = 0.63–0.68 µm). The best values were obtained for the up-milling direction, but in the area of the smooth execution of the process (Ra = 0.26–0.29 µm), not in the area of the blade entry into the material. A similar relationship was obtained for analysed medians of the arithmetic mean height (Sa) and the root-mean-square height (Sq). However, in the case of the S#3 strategy, the spreads of results were the lowest.     

Use of natural kallikrein-protease inhibitors (contrical and gordox) in the therapy of acute myocardial infarct

The paper reports on the efficacy of the protease inhibitors Contrycal and Hordox in acute myocardial infarction. The authors observed 154 patients, of whom 50 constituted the control group. They used to watch the process in the myocardium with biochemical, radioimmune and electrocardiographic methods. It was established that Contrycal (Hordox) used in the combined therapy of acute myocardial infarction during the first hours of the disease is effective.     

A chicken model for DGCR6 as a modifier gene in the DiGeorge critical region

DGCR6 is the most centromeric gene in the human DiGeorge critical region and is the only gene in the region with a second functional copy on a repeat localized more distally on chromosome 22. We isolated the chicken ortholog of DGCR6 and showed an embryonic expression pattern that is initially broad but becomes gradually restricted to neural crest cell derivatives of the cardiovasculature. Retrovirus based gene transduction was used to deliver sense and antisense messages to premigrating neural crest cells in vivo. Embryos in which DGCR6 expression was attenuated revealed cardiovascular anomalies reminiscent of those found in DiGeorge syndrome. Moreover, the expression profiles of three other genes from the DiGeorge critical region, TBX-1, UFD1L, and HIRA, were shown to be altered in this model. TBX-1 and UFD1L levels were increased, whereas HIRA was decreased in the hearts and pharyngeal arches of embryos treated with antisense or partial sense constructs, but not with sense constructs for DGCR6. The expression changes were transient and followed the normal DGCR6 expression profile. These data show that neural crest cells might have a role in the distribution of modulator signals to the heart and pharyngeal arches. Moreover, it shows a repressor function for DGCR6 on the expression of TBX-1 and UFD1L. For the first time, DiGeorge syndrome is shown to be a contiguous gene syndrome in which not only several genes from the critical region, but also different cell types within the embryo, interact in the development of the phenotype.     

Arterial hypertension,its metabolic aspects and kidney function in patients after hemorrhagic fever with renal syndrome

AIM: To characterize late convalescence after hemorrhagic fever with renal syndrome (HFRS), i.e. metabolic disorders and their relation with arterial pressure (AP) and renal function. MATERIAL AND METHODS: 202 HFRS convalescents were followed up with measurements of AP, purin, carbohydrate and lipid metabolisms, study of glomerular and tubular dysfunctions. RESULTS: A stable rise of arterial pressure registered in 24% HFRS convalescents was associated with intraglomerular hypertension, affected concentration ability of the kidneys and tubular transport of beta 2-microglobulin in the presence of metabolic disorders: hyperuricemia, hyperinsulinemia and hyperlipidemia of type IIa. A significant correlation was found between arterial hypertension and renal dysfunction and metabolic disorders. CONCLUSION: Late convalescence after HFRS is characterized by glomerular and tubular dysfunctions, persistent elevation of AP and hormonal-metabolic atherogenic and diabetogenic disturbances.     

Determination of type-specific synthetic peptide antibodies to hepatitis delta virus ]

Nine peptides from immunodominant (53-68 and 65-80 aa) and hypervariable (201-213 aa) regions derived from delta antigen sequences corresponding to 3 HDV genotypes were synthesized. Type specificity of antibodies to the resultant peptides was evaluated by indirect enzyme immunoassay with sera from patients with hepatitis D and asymptomatic carriers of anti-delta antibodies. Analysis of the results showed that HDV circulating in the Central Volga region belongs to type I in the majority of cases. High heterogeneity and changeability of HDV genome during the period of transition from acute forms to asymptomatic carriership was revealed. Possibility of circulation of new hybrid HDV strains causing mixed infection in Russia is discussed.     

The effect of changes in Medicare reimbursement on the practice of office and hospital‐based endoscopic surgery for bladder cancer

BACKGROUND:

Procedures performed in the office offer potential cost savings. Recent analyses suggest, however, that a fee‐for‐service system may incentivize subscale operations and, thus, contribute to excessive spending. The authors of this report sought to characterize changes in the practice of office‐based and hospital‐based endoscopic bladder surgery after 2005 increases in Medicare reimbursement.

METHODS:

All office and hospital‐based endoscopic surgeries that were performed in a faculty practice from 2002 through 2007 were identified using billing codes for procedures, diagnoses, and procedure locations and then analyzed using the chi‐square test and logistic regression. Costs were estimated based on published Medicare reimbursements for office and hospital‐based surgeries.

RESULTS:

In total, 1341 endoscopic bladder surgeries were performed, including 764 in the office and 577 in the hospital. After 2005, the odds ratio (OR) for office surgery occurring among all cystoscopies and for surgery occurring in the office versus the hospital was 2.01 (95% confidence interval [CI], 1.71‐2.37) and 2.29 (95% CI, 1.83‐2.87), respectively. Among all treated lesions that were associated with a diagnosis of bladder cancer and nonbladder cancer, the OR for a procedure occurring in the office versus the hospital was 1.36 (95% CI, 1.07‐1.73) and 1.99 (95% CI, 1.52‐2.60), respectively. The likelihood of repeat surgery on the same lesion increased after 2005 (OR, 2.86; 95% CI, 1.46‐5.62), and the likelihood of an office surgery leading to a bladder cancer diagnosis at the next visit declined (OR, 0.29; 95% CI, 0.16‐0.51). The overall estimated expenditure increased by 50%.

CONCLUSIONS:

After 2005, more bladder lesions were identified and treated in the office. In a single group practice, office treatment of bladder cancer did not fully explain this new practice pattern, suggesting a lowered threshold for office intervention. Cancer 2010. © 2010 American Cancer Society.