The influence of brake pads thermal conductivity on passanger car brake system efficiency

In phase of vehicle braking system designing, besides of mechanical characteristics, it is also necessary to take under consideration the system's thermal fatures. This is because it is not enough just to achieve proper braking power, for the brake system to be effective but equally important thing is the dissipation of heat to the environment. Heat developed in the friction surfaces dissipate into the environment over the disk in one hand and through the brake linings and caliper, in the other. The striving is to make that greatest amount of heat to dissipate not threw the brake pads butthrew disc. The experimental researching of heat transfer process taking place at vehicle brakes was made in the R&D Center of Zastava automobili car factory in order to increase the efficiency of brake system. The standard laboratory and road test procedures were used, according to factory quality regulations. The modern equipment such as thermo camera, thermo couples, torque transducers, signal amplifiers, optical speed measuring system and laptop computer were used. In this paper will be shown the part of the experimental researching, whichrefers to the thermal conductivity ofbrake pad friction linings

Silicon modulates root phenomics and leaf ionomics in oak under Phytophthora infection and low phosphorus conditions

Pedunculate oak (Quercus robur L.) is the most abundant deciduous tree species in Europe with high economical and ecological importance. Different species of Phytophthora are considered as one of the most important factors responsible for deterioration of oak forest, causing serious root damage not only in the forest trees, but also in the nurseries. Oak seedlings were grown in plastic pots with extremely low phosphorus (P) soil (1.5 mg kg-1 total P; no available Olsen-P detected). Silicon (Si) and P were supplied as Na2SiO3 (300 mg Si kg-1 dry soil) and KH2PO4 (180 mg P kg-1 dry soil), respectively. Four treatments (-P/-Si, -P+/Si, +P/-Si, and +P/+Si) were used in the experiment. After two months of experiment, a half of the plants in each treatment were root-inoculated with Phytophthora plurivora. After further four weeks, the first symptoms of P. plurivora infection appeared in leaves (e.g., leaf necrosis and wilting). Plants were then carefully removed from the pots, divided into roots and shoots, and the roots were scanned and analyzed by the WinRHIZO® software. Foliar concentrations of Si, P, K, Ca, Mg, B, Cu, Fe, Mn, and Zn were determined by ICP-OES, while the concentrations of N and S were determined by CHNS Analyzer. The addition of Si obviously improved root health status (e.g., decreasing de number of lesions and necrosis intensity) in the infected plants grown under -P conditions, which was followed by an increased foliar P concentration. The Si supply significantly increased the root variables (e.g., total root volume, root length, and area of thin roots) in both -P and +P plants inoculated with P. plurivora. Therefore, P. plurivora infection and supply of P and Si modulated the nutrient uptake and thereby changed the leaf ionomics, especially for infected -P plants supplied with Si (e.g., significantly increased B, Cu, and Si foliar concentrations and decreased Fe, Mn, Ca, Mg, K, and S foliar concentrations). Furthermore, Si fertilization significantly declined loses in plant dry biomass caused by P. plurivora infection and/or P deficiency, showing biomass comparable to non-infected +P plants

Characterization of a low cost Lagenaria vulgaris based carbon for ranitidine removal from aqueous solutions

Practical aspects of Lagenaria vulgaris shell conversion to activated carbon were examined along with its use in ranitidine adsorption. Kinetics and isotherms of adsorption onto Lagenaria vulgaris carbon (LVC) were correlated to several theoretical adsorption models. The best fit was found in the case of Langmuir and pseudo-second-order model indicating monolayer adsorption. The influence of pH under kinetic study showed slightly hindered adsorption below pH 4. The optimal adsorbent dosage was set to 1 g/L. LVC was characterized by several complementary techniques, including wet chemical techniques such as Boehm's titrations and determination of pH(pzc) and pH of LVC, which revealed neutral nature of the adsorbent. N-2 sorptometry determined specific surface area of 665 m(2)/g and significant ratio of micropores in the sample with maximum wall's diameter of 2.2 nm. Fourier transform infrared spectroscopy (FTIR) confirmed the role of lignin and cellulose in the formation of the final LVC structure. Porous structure of the material was proved by using scanning electron microscopy. Preparation of LVC material drew attention as an easy and low-cost process for production of a highly efficient adsorbent which exhibited fast kinetics of ranitidine removal in the first minutes of contacting and large adsorption capacity (315.5 mg/g) at equilibrium

Impact of fluid balance and opioid-sparing anesthesia within enchanced recovery pathway on postoperative morbidity after transthoracic esophagectomy for cancer

BackgroundEnhanced Recovery After Surgery (ERAS) protocol for esophagectomy may reduce the high incidence of postoperative morbidity and mortality. The aim of this study was to assess the impact of properly conducted ERAS protocol with specific emphasis on fluid balance and opioid-sparing anesthesia (OSA) on postoperative major morbidity and mortality after esophagectomy.MethodsPatients undergoing elective esophagectomy for esophageal cancer at the Hospital for Digestive Surgery, University Clinical Center of Serbia, from December 2017 to March 2021, were included in this retrospective observational study. Patients were divided into two groups: the ERAS group (OSA, intraoperative goal-directed therapy, and postoperative “near-zero” fluid balance) and the control group (opioid-based anesthesia, maintenance mean blood pressure ≥ 65 mmHg, and liberal postoperative fluid management). The primary outcome was major morbidity within 30 days from surgery and 30-day and 90-day mortality. Multivariable analysis was used to examine the effect of the ERAS protocol.ResultsA total of 121 patients were divided into the ERAS group (69 patients) and the control group (52 patients). Patients in the ERAS group was received less fentanyl, median 300 (interquartile range (IQR), 200–1,550) mcg than in control group, median 1,100 (IQR, 650–1750) mcg, p < 0.001. Median intraoperative total infusion was lower in the ERAS group, 2000 (IQR, 1000–3,750) mL compared to control group, 3,500 (IQR, 2000–5,500) mL, p < 0.001. However, intraoperative norepinephrine infusion was more administered in the ERAS group (52.2% vs. 7.7%, p < 0.001). On postoperative day 1, median cumulative fluid balance was 2,215 (IQR, −150-5880) mL in the ERAS group vs. 4692.5 (IQR, 1770–10,060) mL in the control group, p = 0.002. After the implementation of the ERAS protocol, major morbidity was less frequent in the ERAS group than in the control group (18.8% vs. 75%, p < 0.001). There was no statistical significant difference in 30-day and 90-day mortality (p = 0.07 and p = 0.119, respectively). The probability of postoperative major morbidity and interstitial pulmonary edema were higher in control group (OR 5.637; CI95%:1.178–10.98; p = 0.030 and OR 5.955; CI95% 1.702–9.084; p < 0.001, respectively).ConclusionA major morbidity and interstitial pulmonary edema after esophagectomy were decreased after the implementation of the ERAS protocol, without impact on overall mortality

Bucureºti) ♦ 60♦ Nr

In the paper are shown the results of research in ultrasound waves (ultrasound

C - reactive protein and chitinase 3-like protein 1 as biomarkers of spatial redistribution of retinal blood vessels on digital retinal photography in patients with diabetic retinopathy

The aim of the study was to investegate the correlation between the levels of CRP and YKL-40 in blood samples with morphometric parameters of retinal blood vessels in patients with diabetic retinopathy. Blood laboratory examination of 90 patients included the measurement of glycemia, HbA1C, total cholesterol, LDL-C, HDL-C, triglycerides and CRP. Levels of YKL-40 were detected and measured in serum by ELISA (Micro VueYKL-40 EIA Kit, Quidel Corporation, San Diego, USA). Morphmetric analysis was performed with ImageJ software (http://rsbweb.nih.gov/ij/) for digital retinal photography. We measured the number, diameter of retinal blood vessels in five different parts concentric to the optic disc. Differences between the morphometric parameters and the blood test analysis results were evaluated using the Student’s t – test. One Way ANOVA was used to establish the significance of differences. CRP and YKL-40 levels were moderately higher in the group of patients with severe diabetic retinopathy. Levels of YKL-40 correlated positively with diameter and negatively with number of retinal blood vessels. The average number of the blood vessels per retinal zone was significantly higher in the group of patients with mild non-proliferative diabetic retinopathy than in the group with severe form in the optic disc and all five retinal zones. The average outer diameter of the evaluated retinal zones and optic disc vessels was significantly higher in the group with severe compared to the group with mild diabetic retinopathy. Morphological analysis of the retinal vessels on digital fundus photography and correlation with YKL-40 may be valuable for the follow-up of diabetic retinopathy

Forces required to dynamize sliding screws in gamma nail and selfdynamizable internal fixator

Abstract Background Single limb support phase of the gait-cycle in patients who are treated for a pertrochanteric fracture is characterized by transversal loads acting on the lag screw, tending to block its dynamization. If the simultaneous axial force overcomes transversal loads of the sliding screw, the dynamization can still occur. Methods Biomechanical investigation was performed for three types of dynamic implants: Gamma Nail, and two types of Selfdynamizable Internal Fixators (SIF) – SIF-7 (containing two 7 mm non-cannulated sliding screws), and SIF-10 (containing one 10 mm cannulated sliding screw). Contact surface between the stem and the sliding screws is larger in SIF implants than in Gamma Nail, as the stem of Gamma Nail is hollow. A special testing device was designed for this study to provide simultaneous application of a controlled sliding screws bending moment and a controlled transversal load on sliding screws (Qt) without using of weights. Using each of the implants, axial forces required to initiate sliding screws dynamization (Qa) were applied and measured using a tensile testing machine, for several values of sliding screws bending moment. Standard least-squares method was used to present the results through the linear regression model. Results Positive correlation between Qt and Qa was confirmed (p < 0.05). While performing higher bending moments in all the tested implants, Qa was higher than it could be provided by the body weight. It was the highest in Gamma Nail, and the lowest in SIF-10. Conclusions A larger contact surface between a sliding screw and stem results in lower forces required to initiate dynamization of a sliding screw. Patients treated for a pertrochanteric fracture by a sliding screw internal fixation who have longer femoral neck or higher body weight could have different programme of early postoperative rehabilitation than lighter patients or patients with shorter femoral neck

TOTAL HIP ARTHROPLASTY IN PATIENTS SUFFERING FROM RHEUMATOID ARTHRITIS – A REPORT ON TWO CASES

Rheumatoid arthritis is traditionally considered a chronic, inflammatory autoimmune disorder of unknown etiology.It is a disabling and painful inflammatory condition, which can lead to substantial loss of mobility due to pain and joint destruction. Clinical characteristics of the rheumatoid hip are pain, limited range of motion, and rapid onset of cartilage destruction resulting in secondary changes in other lower limb joints and the spine. Radiography showed intensive osteoporosis and later protrusion of acetabulum. Treatment of rheumatoid coxitis is specific, which depends on the stage of disease, subjective and objective complications, and can be medicamentous, functional and operative.The study presents the treatment of two patients with rheumatoid arthritis with total hip arthroplasty at the Clinic of Orthopaedics and Traumatology Clinical Center Nis. In a fifty-five-old patient with the diagnosis of rheumatoid arthritis, the rheumatoid hip joint underwent a cementless total hip arthroplasty. In a sixty-eight-year old patient, the rheumatoid hip joint underwent total hip arthroplasty with cement. In both patients we obtained good functional results.Total hip arthroplasty in patients with rheumatoid coxitis relieves pain and prevents invalidity conditioned by destruction of the hip joint