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In this study, the modelling of arithmetical mean roughness after turning of C45 steel was performed. Four parameters of cutting tool geometry were varied, i.e.: corner radius r, approach angle κ, rake angle γ and inclination angle λ. After turning, the arithmetical mean roughness Ra was measured. The obtained values of Ra ranged from 0.13 μm to 4.39 μm. The results of the experiments showed that surface roughness improves with increasing corner radius, increasing approach angle, increasing rake angle, and decreasing inclination angle. Based on the experimental results, models were developed to predict the distribution of the arithmetical mean roughness using the response surface method (RSM), Gaussian process regression with two kernel functions, the sequential exponential function (GPR-SE) and Mattern (GPR-Mat), and decision tree regression (DTR). The maximum percentage errors of the developed models were 3.898 %, 1.192 %, 1.364 %, and 0.960 % for DTR, GPR-SE, GPR-Mat, and RSM, respectively. In the worst case, the maximum absolute errors were 0.106 μm, 0.017 μm, 0.019 μm, and 0.011 μm for DTR, GPR-SE, GPR-Mat, and RSM, respectively. The results and the obtained errors show that the developed models can be successfully used for surface roughness prediction. [ABSTRACT FROM AUTHOR]

This study is focused on dry longitudinal turning of AISI steel using CVD coated cutting inserts. The machining was conducted at different levels of cutting speed, feed, depth of cut, corner radius, rake, inclination and approach angles. Surface roughness was measured after each experiment, and statistical analysis was used to derive an empirical, regression model for arithmetical mean surface roughness. The regression model was used to theoretically minimize surface roughness, followed by additional verification experiments. The 95 % confidence interval constructed using ten additional batteries of experiments, contained the theoretically predicted minimum roughness of Ra = 0.238 μm. The mean absolute prediction error of the optimal roughness equals 0.006 μm. The results reveal practical applicability of the developed model. (Received in March 2022, accepted in July 2022. This paper was with the authors 1 week for 1 revision.) [ABSTRACT FROM AUTHOR]

The main challenges to overcome within the Fenton process are the acidic pH as an optimal reaction condition, sludge formation in neutral pH medium and high toxicity of treated printing wastewater due to the generation of contaminating by-products. This research discusses the catalytic activity of homogeneous (FeSO 4 /H 2 O 2 ) and heterogeneous (Fe 2 (MoO 4 ) 3 /H 2 O 2 ) Fenton processes in treatment of Yellow azo printing dye in synthetic aqueous solution and real printing effluent, with an integration of adsorption on functionalized biochar synthesized from wild plum kernels. The definitive screening design (DSD), was used to design the experiment. Independent variables were initial dye concentration (20-180 mg L -1 ), iron concentration (0.75-60 mg L -1 ), pH (2-10) and hydrogen peroxide concentration (1-11 mM). Higher decolourization efficiency of 79% was obtained within homogeneous Fenton treatment of printing wastewater, in comparison to heterogeneous Fenton treatment (54%), after a reaction time of 60 min. Same trend of mineralization degree was established: COD removal was 59% and 33% for homogeneous and heterogeneous Fenton process, respectively. The application of adsorption treatment has achieved significant advantages in terms of toxicity reduction (95%) and decolourization efficiency (90% of TOC removal and 22% of dye removal) of treated samples, even at neutral pH medium. Degradation mechanisms within Fenton and adsorption processes were proposed based on the qualitative gas chromatography/mass spectrometry analysis, physico-chemical properties of dye degradation products and functionalized biochar. Overall, the homogeneous Fenton/adsorption combined process can be potentially used as a treatment to remove azo dyes from contaminated water.

The effect of ion nitriding and nitriding in a melamine-based powder mixture on the structure and properties of AISI A290C1M steel was studied in the paper. Using ion nitriding made it possible to shorten the technological cycle's duration by 5-6 times compared to two-stage nitriding, optimize the diffusion layer's composition, provide a technologically simple process automation scheme, and improve the quality of nitride coatings. After the proposed mode of ion nitriding, a saturated layer depth of 0.25-0.32 mm, hardness up to 1000 HV, and an increase in wear resistance by 2.17 times were obtained. Using 95% melamine + 5% sodium fluoride during nitriding in a powder mixture significantly simplified the technological process. It did not require additional expensive equipment, which in turn significantly simplified the nitriding process with energy savings. The proposed technology and the composition of the mixture contributed to a significant acceleration of the nitriding process of AISI A290C1M steel, compared to traditional gas nitriding, and to obtain a hardness of the nitride layer of 970 HV and an increase in wear resistance by 2.6 times. A nitriding speed is explained by a significantly higher amount of atomic nitrogen when using melamine instead of ammonia and by the almost simultaneous disintegration of nanodispersed particles when the nitriding temperature was reached. After nitriding in a powder mixture, steel was subject to the slightest wear.

This paper examines the impact of the CO 2 laser parameters on the tensile strength, which is one of the most important properties of paper packaging in the process of cutting paper material. The study was performed on a paper material sample Fbb Board/Ningbo Spark C1S Ivory Board by examination of the influence of four independent variables: paper material grammage, cutting speed, laser power, and resolution on the tensile strength by using definitive screening design. Optimum process conditions of four variables that maximize the tensile strength were predicted and validated accordingly. Results confirm that laser power, paper material grammage, and cutting speed are the main process parameters that mostly affect the tensile strength. Besides individual parameters, two statistically significant interactions were obtained: laser power and cutting speed, and cutting speed and laser resolution. Maximum tensile strength values (20.37 N/mm) were achieved using the laser power of 60.6%, cutting speed of 3.24%, resolution of 2500 Hz, and a paper material grammage of 326.85 g/m 2 . With laser power at middle values and at a lower speed, a maximum tensile strength value can be obtained. Increasing the laser power and cutting speed will produce a slight lowering of tensile strength.

The paper presents the influence of impression methods, polymer materials, and implant angulation on the accuracy of the definitive working model for the production of implant-supported dental restorations, based on the analysis of results obtained using different impression methods, materials, and parallel and angulated implants. The study findings indicate that all aforementioned factors impact the accuracy of the definitive working model. Specifically, 20° implant angulation in relation to the vertical plane has a greater impact on the impression accuracy compared to parallel implants. The open and splint method in combination with addition silicone, as well as the splint method and polyether combination yielded more accurate results when using implants under 20° angulation compared to other method and material combinations. The splint method in combination with addition silicone resulted in the smallest mean deviations from the center of the parallel implant base compared to other combinations of methods and materials. Analysis results further revealed statistically significant differences in the measured indicators across impression methods, implants, and polymer materials.

In investigating thermally sprayed Ni-based self-fluxing alloy coatings, widely applied under conditions of wear, corrosion, and high temperatures, designed experiments and statistical methods as a basis for modeling and optimization have become an important tool in making valid and comparable conclusions. Therefore, this paper gives an overview of investigating Ni-based self-fluxing alloy coatings deposited by thermal spraying by the use of designed experiments and statistical methods. The investigation includes the period of the last two decades and covers the treatments of flame spraying, high-velocity oxy/air fuel spraying, plasma spraying, plasma-transferred arc welding, and laser cladding. The main aim was to separate input variables, as well as measured responses, and to point out the importance of correct application of statistical design of experiment. After the review of the papers, it was concluded that investigators have used the process knowledge to analyze and interpret the results of the statistical analysis of experimental data, which is in fact the best way of using the design of experiment in every research. Nevertheless, more attention should be given to correct planning and conducting the experiments to derive the models suitable for the prediction of measured response and which could be an appropriate input for single- or multi-objective optimization.

This study analysed the impact of the production of high-density polyethylene (HDPE) caps on the environment. To determine the environmental impact of injection moulding production, a life-cycle assessment was performed. The life-cycle assessment results showed that, in the injection moulding tool manufacturing process, the largest amount of environmental loading is attributable to electricity and steel consumption. Additionally, the HDPE cap production phase had the largest environmental impact associated with electricity consumption. However, scenario analysis showed that the environmental impact from electricity consumption can be reduced by up to ten times if cleaner sources of electricity are used. Large differences related to electricity sourcing should help developing countries to better understand the need to increase the use of cleaner sources of electricity., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Nowadays every piece of working equipment and tools has to comply with safety standards and laws. This study investigated multi-criteria methods for selecting working equipment in order to optimize performance and occupational safety. The multi-criteria decision-making (MDCM) method was applied to the problem of selecting optimal working equipment using four different criterion weighting approaches (direct weighting, revised Simos procedure, Fuller's triangle and analytic hierarchy process). Groups of economic, technical and safety criteria were defined and five weighting scenarios were developed. Although the four weighting methods produced similar results, in some situations they produced different criterion weighting factors. The final output of the MCDM method was the identification of the optimal forklift in the five weighting scenarios. Although we have applied the MCDM method to a forklift selection problem, it can be applied to all sorts of working equipment in contexts where economic, technical and safety selection criteria can be identified.

Background and Objectives: Nowadays, the integrated CAD/CAE systems are favored solutions for the design of simulation models for casting metal substructures of metal-ceramic crowns. The worldwide authors have used different approaches to solve the problems using an expert system. Despite substantial research progress in the design of experts systems for the simulation model design and manufacturing have insufficiently considered the specifics of casting in dentistry, especially the need for further CAD, RE, CAE for the estimation of casting parameters and the control of the casting machine. The novel expert system performs the following: CAD modeling of the simulation model for casting, fast modeling of gate design, CAD eligibility and cast ability check of the model, estimation and running of the program code for the casting machine, as well as manufacturing time reduction of the metal substructure., Methods: The authors propose an integration method using common data model approach, blackboard architecture, rule-based reasoning and iterative redesign method. Arithmetic mean roughness values was determinated with constant Gauss low-pass filter (cut-off length of 2.5mm) according to ISO 4287 using Mahr MARSURF PS1. Dimensional deviation between the designed model and manufactured cast was determined using the coordinate measuring machine Zeiss Contura G2 and GOM Inspect software., Results: The ES allows for obtaining the castings derived roughness grade number N7. The dimensional deviation between the simulation model of the metal substructure and the manufactured cast is 0.018mm. The arithmetic mean roughness values measured on the casting substructure are from 1.935µm to 2.778µm., Conclusions: The realized developed expert system with the integrated database is fully applicable for the observed hardware and software. Values of the arithmetic mean roughness and dimensional deviation indicate that casting substructures are surface quality, which is more than enough and useful for direct porcelain veneering. The manufacture of the substructure shows that the proposed ES allows the improvement of the design process while reducing the manufacturing time., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Dental alloys for direct metal laser sintering (DMLS) are available on the market today, but there is little scientific evidence reported on their characteristics. One of them is the release of ions, as an indicator of the corrosion characteristics of a dental alloy. Within this research, the difference in the elution of metals from DMLS and cast (CM) samples of Co-Cr-Mo dental alloy in saliva-like medium of three different pH was examined by inductively-coupled plasma mass spectrometry (ICP-MS). The obtained results show that the metal elution in artificial saliva from the DMLS alloy was lower than the elution from the CM alloy. The release of all investigated metal ions was influenced by the acidity, both from the DMLS and CM alloy, throughout the investigated period of 30 days. The change in acidity from a pH of 6.8 to a pH of 2.3 for the cast alloy led to a higher increase of the elution of Co, Cr and Mo from CM than from the DMLS alloy. The greatest release out of Co, Cr and Mo was for Co for both tested alloys. Further, the greatest release of all ions was measured at pH 2.3. In saliva of pH 2.3 and pH 4.5, the longer the investigated period, the higher the difference between the total metal ion release from the CM and DMLS alloys. Both alloys showed a safe level of elution according to the ISO definition in all investigated acidic environments.

Aim: To investigate the relationship between plasma and cyst concentrations of albendazolesulphoxide (ASO) and their effects on parasitological findings and disease recurrence in patients with liver hydatidosis., Methods: The study was conducted at the University Hospital for Infectious Diseases Dr. Fran Mihaljević, Zagreb, Croatia, between August 2006 and January 2011. Consecutive patients (N=48, age 6-77 years) were treated with albendazole (3×5 mg/kg/d) over 28 days before surgical cyst removal (n=34) or percutaneous evacuation (PAIR) (n=14). Plasma ASO was determined on days 10 and 28 of treatment and cyst concentrations at surgery/PAIR., Results: Disease recurred in 3 surgically treated patients. Variability of ASO concentrations was substantial. Plasma concentrations on day 10 were higher than on day 28 (geometric means ratio [GMR] 2.00; 95%CI 1.38-2.91, P<0.001) and higher than cyst concentrations at the time of treatment (GMR=1.58, 1.01-2.34, P=0.045). Higher cyst (but not plasma) concentrations were independently associated with lower odds of protoscolex motility (OR=0.23, 0.01-0.70, P<0.001) and higher odds of protoscolex destruction (OR=1.17, 1.04-1.46, P<0.001). With adjustment for age and protoscolex motility, higher day 10 plasma concentrations (but not cyst concentrations) were associated with lower odds of disease recurrence (OR=0.49, 0.09-0.97, P=0.035). Plasma concentrations did not predict cyst concentrations., Conclusion: Viability of protoscolices progressively decreased with increasing ASO concentrations in the cyst. Data strongly suggested that higher plasma concentrations reduced the risk of disease recurrence.

Background: Primary prevention of acute rheumatic fever is achieved by proper antibiotic treatment of group A β -hemolytic streptococcal (GAS) pharyngitis., Methods: To assess noninferiority of oral amoxicillin to intramuscular benzathine penicillin G (IM BPG). Children (2 to 12 years) meeting enrollment criteria were randomized 1:1 to receive antibiotic treatment in 2 urban outpatient clinics in Egypt and Croatia., Results: A total of 558 children (Croatia = 166, Egypt = 392) were randomized, with 368 evaluable in an intention-to-treat (ITT) analysis, and 272 evaluable in the per protocol (PP) analysis. In Croatia, ITT and PP treatment success rates were comparable for IM BPG and amoxicillin (2.5% difference vs 1.1% difference, respectively). In Egypt, amoxicillin was not comparable with IM BPG in ITT analysis (15.1% difference), but was comparable in PP analysis (-9.3% difference)., Conclusion: If compliance is a major issue, a single dose of IM BPG may be preferable for treatment of GAS pharyngitis.

Objective: To evaluate efficacy of a single oral azithromycin dose versus standard oral erythromycin regimen or no antibiotic for Campylobacter enterocolitis in children younger than or equal to 12 years of age., Patients and Methods: Randomized parallel group assessor-blind trial testing for inequality in efficacy between treatments was done. Patients (N = 120) were enrolled at less than or equal to 48 hours since disease onset to receive erythromycin 50 mg kg day for 5 days, single-dose azithromycin 20 mg/kg or 30 mg/kg, or no antibiotic (no treatment control) (1: 1: 1: 1). Antibiotics were commenced 8 to 10 hours after enrollment. Patients were assessed at 24-hour intervals for 6 days., Results: In the intent-to-treat analysis, Campylobacter eradication was achieved in 20 of 30 controls and in all of the patients treated with antibiotic. Incidence of clinical cure during the observed period was 15 of 30 in the control, 14 of 30 in the erythromycin, 20 of 30 in the lower, and 25 of 30 in the higher azithromycin dose group. With adjustment for age, sex, baseline disease severity, and disease duration before enrollment, only azithromycin 30 mg/kg was superior to no treatment: incidence ratio (IR) 1.76 (95% confidence interval [CI] 1.11-2.87). It was also superior to erythromycin (IR 1.80, 97.5% CI 1.13-2.84). Regarding time to clinical cure, only azithromycin 30 mg/kg was superior to no treatment (adjusted hazard ratio [HR] 4.90, 95% CI 2.44-9.84). It was also superior to erythromycin (HR 4.17, 97.5% CI 1.91-9.09). All treatments were well tolerated., Conclusions: The administration of single oral dose of azithromycin 30 mg/kg early after disease onset effectively eradicates the pathogen and accelerates clinical cure in childhood Campylobacter enterocolitis. It is clinically superior to an early commenced 5-day erythromycin regimen, which apparently conveys no clinically relevant benefit over no antibiotic treatment.

Opsoclonus-myoclonus is a rare neurological syndrome affecting children and adults. In children it occurs as a parainfectious process or a paraneoplastic syndrome in association with neuroblastoma. Here we report it presenting as an unusual neurological manifestation of Lyme borreliosis. To our knowledge, this is the first report which describes recovery from this syndrome in a child.