Optimization of 3D printing parameters in polylactic acid bio-metamaterial under cyclic bending loading considering fracture features.

3D printing has become a crucial additive manufacturing technique with the applications in various industries. Fused deposition modeling (FDM) is a common additive manufacturing process that offers considerable flexibility in the component fabrication through multiple parameters, which strongly influence the properties of the produced parts. This study focused on the impact of different printing parameters on the fatigue behavior of polylactic acid (PLA). The standard samples were 3D-printed with varying speed (5, 10, and 15 mm/s), print temperature (180, 210, and 240 °C), and nozzle diameter (0.2, 0.4, and 0.6 mm). The fatigue properties were evaluated through rotating bending fatigue tests, and a model was developed based on the results with a statistical analysis. The model accuracy was validated and the interactions between the parameters were analyzed. The optimization study found that a print speed of 5 mm/s, print temperature of 210 °C, and nozzle diameter of 0.2 mm were optimal. The fracture surfaces were also examined using a scanning electron microscopy, revealing the presence of crazing despite the brittle behavior of PLA.

Multi-objective numerical optimization of 3D-printed polylactic acid bio-metamaterial based on topology, filling pattern, and infill density via fatigue lifetime and mass.

Infill parameters are significant with regard to the overall cost and saving material while printing a 3D model. When it comes to printing time, we can decrease the printing time by altering the infill, which also reduces the total process extent. Choosing the right filling parameters affects the strength of the printed model. In this research, the effect of filling density and infill pattern on the fatigue lifetime of cylindrical polylactic acid (PLA) samples was investigated with finite element modeling and analysis. This causes the lattice structure to be considered macro-scale porosity in the additive manufacturing process. Due to the need for multi-objective optimization of several functions at the same time and the inevitable sacrifice of other objectives, the decision was to obtain a set of compromise solutions according to the Pareto-optimal solution technique or the Pareto non-inferior solution approach. As a result, a horizontally printed rectangular pattern with 60% filling was preferred over the four patterns including honeycomb, triangular, regular octagon, and irregular octagon by considering the sum of mass changes and fatigue lifetime changes, and distance from the optimal point, which is the lightest structure with the maximum fatigue lifetime as an objective function with an emphasis on mass as an important parameter in designing scaffolds and biomedical structures. A new structure was also proposed by performing a structural optimization process using computer-aided design tools and also, computer-aided engineering software by Dassault systems. Finally, the selected samples were printed and their 3D printing quality was investigated using field emission scanning electron microscopy inspection.

The nutritional quality of a fresh orange pulp-wheat straw mixture ensiled with either sugar beet pulp, wheat bran, or urea compared to corn silage (Zea mays) in sheep.

This study compares corn silage (CS) with an orange pulp-wheat straw mixture (OW) ensiled with either sugar beet pulp (SBP), wheat bran (WB), or urea in terms of intake, chemical composition, phenolic compounds, silage fermentation characteristics, digestibility, in vivo rumen variables and biochemical blood variables in 48 Shall male sheep, and in vitro methane (CH4) production. In addition to CS, five other silages: OW (i.e., 87.5% fresh orange pulp + 12.5% wheat straw); OWU (OW + 1% urea); OWS (87.5% fresh orange pulp + 8.6% wheat straw + 3.9% SBP); OWSU (87.5% fresh orange pulp + 8.6% wheat straw + 1% urea + 3.9% SBP); and OWB (87.5% fresh orange pulp + 8.6% wheat straw + 3.9% SBP) were ensiled for 90 days. All diets, which contained a mineral-vitamin premix (10 g/kg of dry matter [DM]), were each randomly assigned to five sheep (live weight 40 ± 2.5 kg) using a completely randomized design, and the SAS software MIXED method was used for data analysis. Among all silages, OWU and OWSU had the highest (P < 0.01) ammonia-N concentration, but there were no differences in other fermentation characteristics. Animals fed on the CS diet had higher DM intake (P = 0.01) and DM (P = 0.01), organic matter (P = 0.01), and neutral detergent fiber (P = 0.02) digestibilities compared with other diets. However, sheep receiving OWU and OWSU diets had higher (P < 0.01) crude protein digestibility than those fed on other diets. The OWU and OWSU-fed sheep had the highest (P = 0.04) ruminal ammonia-N concentration. Sheep fed on CS had higher (P = 0.03) ruminal total short-chain fatty acids, acetate concentration (P = 0.02), total protozoa (P < 0.01), and cellulolytic bacteria numbers (P < 0.01), but had a lower (P = 0.03) propionate concentration compared with the other sheep. In vitro CH4 production was higher (P = 0.01) with the CS diet compared to the orange pulp diets. Estimated microbial protein supply was lower (P = 0.05) with CS compared to all orange silages. In conclusion, the variation in the nutritive quality among the OWS, OWSU, and OWB is relatively small, and the OWB, which is most comparable to CS, was judged to be nutritionally the best among the diets.

SARS-CoV-2 and HIV co-infection; clinical features, diagnosis, and treatment strategies: A systematic review and meta-analysis.

Background and aim: Coronavirus disease 2019 (COVID-19) in people living with human immunodeficiency virus (HIV) who has a compromised immune system can be associated with more significant risks for severe complications. To date, no comprehensive study has been performed to evaluate HIV in patients with COVID-19. In the present study, we assessed the status of patients co-infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and HIV as a systematic review and meta-analysis. Methods: A systematic literature search strategy was conducted via reviewing original research articles published in Medline, Web of Science, and Embase databases in 2019 and 2020. Statistical analysis was performed using STATA software, version 14.0 (Stata Corporation, College Station, Texas, USA), to report the prevalence of HIV among patients with COVID-19. Case reports/case series were also evaluated as a systematic review. Results: Sixty-three studies (53 case reports/case series and ten prevalence studies) were included in our study. A meta-analysis of prevalence studies showed that HIV infection among patients with COVID-19 was reported in 6 countries (Uganda, China, Iran, USA, Italy, and Spain) with an overall frequency of 1.2% [(95% CI) 0.8-1.7] among 14,424 COVID-19 patients. According to the case reports and case series, 111 patients with HIV have been reported among 113 patients with COVID-19 from 19 countries. Most of the cases were in the USA, China, Italy, and Spain. Conclusion: The small number of SARS-CoV-2-HIV co-infected patients reported in the literature makes it difficult to draw precise conclusions. However, since people with HIV are more likely to develop more severe complications of COVID-19, targeted policies to address this raised risk in the current pandemic should be considered. Our findings highlight the importance of identifying underlying diseases, co-infections, co-morbidities, laboratory findings, and beneficial treatment strategies for HIV patients during the COVID-19 pandemic.

Experimental fatigue dataset for additive-manufactured 3D-printed Polylactic acid biomaterials under fully-reversed rotating-bending bending loadings.

In this dataset, experimental fatigue testing results have been presented for the additive-manufactured 3D-printed Polylactic acid (PLA) biomaterials under fully-reversed rotating-bending loadings. For such an objective, a fused deposition modeling (FDM) 3D-printer was utilized to fabricate the standard cylindrical samples with different printing parameters in the horizontal direction. For the demonstration of printing parameter effects on the PLA fatigue lifetime, the nozzle diameters were from 0.2 to 0.6 mm, the extruder temperatures were from 180 to 240 °C, and finally, the printing speeds were from 5 to 15 mm/s. Then after 3D-printing of specimens, fatigue testing was performed on various samples under fully-reversed rotating-bending loadings. Then, the fatigue data were presented in tables through the high-cycle fatigue regime, under the load-controlled condition. For further works, these dataset tables could be used to draw the S-N (stress-lifetime) diagram, to find the fatigue strength coefficient and exponent.

Effect of biotin supplementation on neuropathic pain induced by chronic constriction of the sciatic nerve in the rat.

BACKGROUND AND PURPOSE: Neuropathic pain is one of the most common types of chronic pain that is very difficult to treat. Numerous studies have shown the potential role of vitamins in relieving both hyperalgesia and allodynia. Based on the convincing evidence, this study was designed to evaluate the possible antinociceptive effect of biotin on neuropathic pain in rats. EXPERIMENTAL APPROACH: This study was performed on male Sprague Dawley rats weighing 200-300 g. Neuropathic pain was induced by tying the sciatic nerve. Chronic constriction injury (CCI) of the sciatic nerve resulted in hyperalgesia and allodynia. To measure the thermal hyperalgesia, the plantar test was used. Also to evaluate the cold and mechanical allodynia, acetone test and von Frey test were applied. Biotin (4, 8, and 16 mg/kg) was administered orally as two different treatment regimens, acute and chronic. FINDINGS/RESULTS: Acute oral administration of biotin (4, 8, and 16 mg/kg p.o.) on the 7th, 14th, and 21st postoperative days couldn't reduce pain sensitivity compared to the CCI group. However, following the oral administration of biotin (8 and 16 mg/kg p.o.) from the first day after the surgery until day 21, mechanical allodynia (P < 0.001) and heat hyperalgesia (P < 0.05) significantly relieved. CONCLUSION AND IMPLICATIONS: Our results suggest that biotin can be considered as a potential therapeutic for the treatment of neuropathic pain, and supplementation with this vitamin could reduce the required doses of analgesic drugs. However, further studies are needed to confirm this hypothesis.

Spatio-temporal mapping of breast and prostate cancers in South Iran from 2014 to 2017.

BACKGROUND: The most common gender-specific malignancies are cancers of the breast and the prostate. In developing countries, cancer screening of all at risk is impractical because of healthcare resource limitations. Thus, determining high-risk areas might be an important first screening step. This study explores incidence patterns of potential high-risk clusters of breast and prostate cancers in southern Iran. METHODS: This cross-sectional study was conducted in the province of Kerman, South Iran. Patient data were aggregated at the county and district levels calculating the incidence rate per 100,000 people both for cancers of the breast and the prostate. We used the natural-break classification with five classes to produce descriptive maps. A spatial clustering analysis (Anselin Local Moran's I) was used to identify potential clusters and outliers in the pattern of these cancers from 2014 to 2017. RESULTS: There were 1350 breast cancer patients (including, 42 male cases) and 478 prostate cancer patients in the province of Kerman, Iran during the study period. After 45 years of age, the number of men with diagnosed prostate cancer increased similarly to that of breast cancer for women after 25 years of age. The age-standardised incidence rate of breast cancer for women showed an increase from 29.93 to 32.27 cases per 100,000 people and that of prostate cancer from 13.93 to 15.47 cases per 100,000 during 2014-2017. Cluster analysis at the county level identified high-high clusters of breast cancer in the north-western part of the province for all years studied, but the analysis at the district level showed high-high clusters for only two of the years. With regard to prostate cancer, cluster analysis at the county and district levels identified high-high clusters in this area of the province for two of the study years. CONCLUSIONS: North-western Kerman had a significantly higher incidence rate of both breast and prostate cancer than the average, which should help in designing tailored screening and surveillance systems. Furthermore, this study generates new hypotheses regarding the potential relationship between increased incidence of cancers in certain geographical areas and environmental risk factors.

Correlation between biofilm formation and carbapenem resistance among clinical isolates of Klebsiella pneumoniae.

BACKGROUND: Klebsiella pneumoniae is a Gram-negative enteric bacterium that causes nosocomial infections; this bacterium has survived from harsh condition using biofilm formation in hospital equipment and cause severe infection. In the other hand, the emergence and extension of carbapenem resistance burden among K. pneumonia producing biofilm is the current concern of public health services. There are controversial findings about this subject. The aim of this study was to evaluate the correlation between biofilm formation and resistance to carbapenem among clinical isolates of K. pneumoniae. METHODS: A total of 160 K. pneumoniae isolates were collected from various infections of hospitalized patients. The Carba NP test and molecular methods were used for detection of carbapenem resistance isolates of K. pneumonia. Subsequently, the ability for biofilm production was performed from all isolates. Finally, Correlation of biofilm formation among carbapenem resistant isolates was calculated using χ2 and Fisher's exact tests. RESULTS: Among K. pneumoniae isolates 42.5% have carbapenemase activity by Carba NP test, while carbapenemase genes were detected in 35.6% of isolates in amplification assay. Moreover, there are 52.5% (n= 84) of all isolates were formed a strong biofilm, while 38.1% (n= 61) and 9.3% (n= 15) of isolates were middle and weak biofilm producer, respectively. Among carbapenem resistant cases (n= 68), there are 77.9% (n= 53) and 22% (n= 15) of isolates were reported as strong and middle biofilm producer, respectively. We see a significant correlation was seen between biofilm formation ability and carbapenem resistant isolates (p-value < 0.00001). CONCLUSION: The increase of carbapenem resistance burden in biofilm producing isolates of K. pneumoniae is considered as serious alert and the basic measures to combat this phenomenon is imperative.

Prioritizing highway safety improvement projects: A Monte-Carlo based Data Envelopment Analysis approach.

Road authorities have to prioritize safety improvement projects due to budget limitations. This process needs to estimate expected benefits (reduction in average crash frequency) and costs of projects. Due to variances of crash modification factor (CMF), crash frequency and cost of projects, prediction of costs and benefits would be accompanied by uncertainty and it can subsequently lead to a wrong decision making. To deal with the inherent uncertainty in the decision making process, this paper presents a ranking approach based on integration of Data Envelopment Analysis and Monte-Carlo simulation. A Monte-Carlo simulation is applied to generate stochastic values as input and outputs of the problem instead of running DEA model just for deterministic case. Data from an existing case study is used to evaluate the performance of the proposed methodology. Numerical results indicate that DEA results are very sensitive to data uncertainty and uncertainties can have great influence in ranking results of road safety improvement projects especially when both input and output data are uncertain. It also indicates that how the proposed methodology can be useful for detecting sensitive decision-making units and providing a more comprehensive view for decision makers to allocate a limit budget to the most efficient safety improvement projects.

User Interface Problems of a Nationwide Inpatient Information System: A Heuristic Evaluation.

INTRODUCTION: While studies have shown that usability evaluation could uncover many design problems of health information systems, the usability of health information systems in developing countries using their native language is poorly studied. The objective of this study was to evaluate the usability of a nationwide inpatient information system used in many academic hospitals in Iran. MATERIAL AND METHODS: Three trained usability evaluators independently evaluated the system using Nielsen's 10 usability heuristics. The evaluators combined identified problems in a single list and independently rated the severity of the problems. We statistically compared the number and severity of problems identified by HIS experienced and non-experienced evaluators. RESULTS: A total of 158 usability problems were identified. After removing duplications 99 unique problems were left. The highest mismatch with usability principles was related to "Consistency and standards" heuristic (25%) and the lowest related to "Flexibility and efficiency of use" (4%). The average severity of problems ranged from 2.4 (Major problem) to 3.3 (Catastrophe problem). The experienced evaluator with HIS identified significantly more problems and gave higher severities to problems (p<0.02). DISCUSSION: Heuristic Evaluation identified a high number of usability problems in a widely used inpatient information system in many academic hospitals. These problems, if remain unsolved, may waste users' and patients' time, increase errors and finally threaten patient's safety. Many of them can be fixed with simple redesign solutions such as using clear labels and better layouts. This study suggests conducting further studies to confirm the findings concerning effect of evaluator experience on the results of Heuristic Evaluation.