Optimization of Aggregate Production Circuit through Modeling of Crusher Operation

The paper concerns investigation of the effect of impact crusher operation on selected qualitative characteristics of mineral aggregate products. Qualitative characteristics of crushing products in terms of size reduction ratio and fine particles contents were analyzed from the point of view of operational parameters of the impact crusher. An investigative program was carried out on a plant scale and two primary parameters of the impactor were analyzed: velocity of the crusher rotor and the width of the outlet gap. The models of the crushing device operation were built separately for each type of the tested material, as well as for general conditions.

RELATIONSHIP BETWEEN WARM ISCHEMIC TIME AND RESISTIVE INDEX ON CREATININ REDUCTION RATIO DAY TWO AFTER LIVING KIDNEY DONOR TRANSPLANTATION

Kidney transplantation (KT) may improve kidney function, via filtration, excretion, and hormonal function better than other kidney replacement therapies. Many factors may cause graft rejection or delayed graft function which may decrease the prognosis for graft survival. This study aims to determine associated factors of serum creatinine reduction ratio day 2 (CRR2) after living kidney donor transplants. This research used a retrospective cohort study design, with total sampling based on complete documents was done. A total 44 respondents (from 2012 to January 2020) and 22 respondents (based on the complete Resistive Index (RI) were recorded since 2018). Early Graft Function was defined using CRR2. Immediate Graft Function (IGF) was defined if CRR2 > 30% and Delayed Graft Function (DGF) if CRR2 ≤ 30%. The results of Multiple logistic regression analysis from 44 samples showed that Warm Ischemic Time (WIT) ≤ 40 minutes was significantly associated with IGF (OR 10.78; 95%CI: 1.66 to 70.16; p=0.01). A result with 22 samples showed that, only RI ≤ 0.7was significantly associated with IGF (OR 0.11; 95%CI: 0.03-0.41; p=0.002). In conclusion, WIT and RI influence on EGF with parameters CRR2 of living-donors. KT Patients with WIT ≤40 minutes and RI ≤0.7 had a higher risk of IGF.

Vitamin D Insufficiency Predicts Susceptibility of Parathyroid Hormone Reduction after Total Thyroidectomy in Thyroid Cancer Patients

Objective. Given its role in the regulation of calcium and PTH levels, vitamin D was presumed as a potential predictor of postoperative hypoparathyroidism. However, the reports about their association were controversial. This study aims to reveal the relationship between preoperative vitamin D and postoperative parathyroid hormone (PTH). Methods. A total of 242 papillary thyroid cancer (PTC) patients who underwent total thyroidectomy (TT) during the period from June 2016 to December 2017 at our hospital were enrolled. Patients were divided into two groups, HypoP and Non-HypoP groups, based on postoperative PTH < 15.0 or ≥15.0 pg/mL, and ΔPTH50+ and ΔPTH50− groups, based on postoperative PTH reduction ratio ≥ 50% or <50%. Clinicopathological features and laboratory data were compared between two sets of groups. Results. Preoperative PTH level was lower in the HypoP group than in the Non-HypoP group (42.83 vs. 47.52 pg/mL, p = 0.018 ). No significant difference of vitamin D insufficiency was found between the HypoP and Non-HypoP groups (80.8% vs. 74.1%, p = 0.226 ). The rate of vitamin D insufficiency was higher in the ΔPTH50+ group than in the ΔPTH50− group (82.6% vs. 68.4%, p = 0.010 ). By multivariate logistic regression analysis, vitamin D insufficiency was an independent predictor of postoperative PTH reduction ratio ≥ 50% (OR = 2.2, p = 0.017 ). Conclusion. Vitamin D insufficiency is not associated with postoperative PTH in PTC patients undergoing TT. However, vitamin D insufficiency is an independent predictor of postoperative PTH reduction ratio.

Comparison of Different Methods For Effective Manual Chest Compression In Dental Chairs, During Cardiopulmonary Resuscitation (CPR): A Manikin Study

During cardiopulmonary resuscitation (CPR), almost commercially dental chairs lack sufficient stability to perform effective manual chest compression (MCC). In our previous study, our technique that stabilizing stool can significantly reduce vertical displacement in a dental chair’s backrest. This study demonstrates that the efficacy of different methods for stabilizing 3 types of dental chair with a flat or a severely curved backrest exterior for effective MCC. Vertical displacement of the dental chair’s backrest was recorded. The data was captured with three different stool positions (no stool, under MCC, under shoulders). Reduction ratios were calculated to evaluate the effectiveness of the stool positions. In all types of dental chair, the technique significantly reduced the vertical displacements of the backrest. The reduction ratio varied nearly 40% under the area for MCC and 65% under the shoulder with a severely curved backrest exterior. With a flat shape of dental chair, these ratios were around 90% versus without a stool. The technique is a firm support and reduce the displacement of any type of dental chair’s backrest for effective MCC.

Effect of Frictional Conditions in Deep Drawing on Formability

This study investigated the stress and strain behavior caused in the forming process via simulation analysis using the finite element method, for suppressing punch shoulder and head plate thickness reduction die shoulder stress concentration by controlling the friction conditions. The following findings were obtained: The thickness of the blank head and punch shoulder decreased with the forming process. Due to the increase in the coefficient of friction with the punch side, the plate thickness reduction ratio decreases, and is the lowest when it is close to non-lubrication; Stress concentration occurs at the die shoulder with forming processing. With the increase in the friction coefficient value, forming limit parameter (FLP) increases slightly, but as it does not reach the limit value of 1, the forming process can be safely performed without mechanical damage; When the formability is comprehensively evaluated using the plate thickness reduction ratio and FLP, the friction coefficient μ = 0.4 to 0.5 is reasonable.

Efficacy on radiofrequency ablation according to the types of benign thyroid nodules

Percutaneous radiofrequency ablation (RFA) has been recommended as minimally invasive treatment for patients with symptomatic benign thyroid nodules (BTNs) because of the large number of clinical applications. This retrospective observational study sought to evaluate the clinical outcomes of RFA for BTNs. From 2014 to 2019, a sample size of 1289 patients treated by RFA were 262 ones with solid nodules and 1027 ones with cystic-solid nodule, respectively. The efficacy including the nodule maximal diameter reduction ratio (MDRR), the volume reduction ratio (VRR) and the cosmetic scores reduction ratio (CSRR). The results of the nodule MDRR and VRR in the cystic-solid nodule group were significantly better than those in the solid nodule group at the 3rd and 6th month, and the CSRR in the two groups showed statistically significant difference at the 3rd month. In a word, RFA is an effective method for symptomatic benign solid or cystic-solid nodules. The achieved MDRR and VRR in the cystic-solid nodule group were significantly better than those in the solid nodule group at the 3rd and 6th month.

Determination of the effect of thickness reduction ratio, die angle, and coefficient of friction on residual stresses in ironing process: an analysis using computer simulation

Ironing is a part of the group of metal forming processes, the process of reducing the thickness of the wall of a cup-shaped product. External load required to process metal forming, can cause residual stress. Residual stress can be beneficial or detrimental depending on the function of the product, the magnitude, and direction of the residual stress. Residual stress can act as an additional load on a given load. Residual stress can affect product quality, namely: dimensional accuracy, surface roughness, and mechanical properties. The speed of the ironing process is strongly influenced by the mechanical properties of the cup material, Thickness Reduction Ratio (TRR), and press tool design. The ironing process has a limited TRR value and if it is exceeded it results in product damage. Various studies on ironing were carried out to obtain an optimal process. In this research, stress analysis was carried out using the ANSYS software modeling simulation to obtain the occurring residual stress during the ironing process. The analysis was carried out by varying the TRR from 20 % to 30 %, the die angle from 25° to 30°, and the coefficient of friction from 0.05 to 0.15. Furthermore, processing and analysis of the stress analysis data are carried out to obtain the most dominant variables affecting the residual stress and the variable value that produces the lowest residual stress. Stress analysis was carried out on AA1100 aluminum cups with an outer diameter of 37 mm, a height of 20 mm, and a wall thickness of 2 mm. The results show that TRR and coefficient of friction are the most dominant variables affecting residual stress, while die angle has no significant effect. The lowest residual stress occurs at TRR 30 % and coefficient of friction 0.15

Ultrasound predictive criteria for short term benign thyroid nodular volume reduction after ultrasound guided radiofrequency ablation

Purpose This study evaluates the outcome of patients complaining of compressive& cosmetic problems due to benign thyroid nodules after recieving RF ablation with correlation between some ultrasound features of the nodules and their shrinkage and volume reduction. Methods and material fifteen patients with benign thyroid nodules causing compressive symptoms (foreign body sensation,neck discomfort or pain) and cosmetic problems. Results A total of 15 patients were included with the age rangmg from 22-82 years old the mean was 52.73 years old (SD + 14.37).Among them 12 patients (800 0)were females and 3 patients(20%) were males. There was statistically significant difference between volume of nodules before the procedure with mean volume was 21.13±5.13 and I month after with mean volume I I .96±3.08 and 3 months after the procedure with mean volume 7.70±2.82 with noticeable improvement in nodules with peri and intranodular vascularity showing mean reduction ratio 69.88% after 3 months vs 59.93% and 64 12% of weak peripheral vascularity and intense intra-nodular vasculanty respectively as well as US structure with spongiform nodules showing mean reduction ratio 68.48% at 3 months vs 59.87% and 62.14% for solid &mixed nodules respectively.Mean symptoms and cosmetic score were significantly reduced. Conclusion: This study validated the efficacy and safety of RFA for treatment of benign thyroid nodules and showed correlation between shrinkage and some common US findings.