Finish machining of hardened gears wheels using cubic boron nitride (CBN) inserts

The paper presents some results of investigation of finish machining of hardened bearing surfaces of cylindrical gear wheels. Finish machining has been performed with wedges of defined geometry made of CBN. The presented investigation results are related mainly to the wear processes of the cutting wedges. Additional results of quality examination of finish machined gear wheels have been presented, too

A standardized comparison of peri-operative complications after minimally invasive esophagectomy: Ivor Lewis versus McKeown.

BACKGROUND: While our institutional approach to esophageal resection for cancer has traditionally favored a minimally invasive (MI) 3-hole, McKeown esophagectomy (MIE 3-hole) during the last five years several factors has determined a shift in our practice with an increasing number of minimally invasive Ivor Lewis (MIE IL) resections being performed. We compared peri-operative outcomes of the two procedures, hypothesizing that MIE IL would be less morbid in the peri-operative setting compared to MIE 3-hole. METHODS: Our institution\u27s IRB-approved esophageal database was queried to identify all patients who underwent totally MI esophagectomy (MIE IL vs. MIE 3-hole) from June 2011 to May 2016. Patient demographics, preoperative and peri-operative data, as well as post-operative complications were compared between the two groups. Post-operative complications were analyzed using the Clavien-Dindo classification system. RESULTS: There were 110 patients who underwent totally MI esophagectomy (MIE IL n = 49 [45%], MIE 3-hole n = 61 [55%]). The majority of patients were men (n = 91, 83%) with a median age of 62.5 (range 31-83). Preoperative risk stratifiers such as ECOG score, ASA, and Charlson Comorbidity Index were not significantly different between groups. Anastomotic leak rate was 2.0% in the MIE IL group compared to 6.6% in the MIE 3-hole group (p = 0.379). The rate of serious (Clavien-Dindo 3, 4, or 5) post-operative complications was significantly less in the MIE IL group (34.7 vs. 59.0%, p = 0.013). Serious pulmonary complications were not significantly different (16.3 vs. 26.2%, p = 0.251) between the two groups. CONCLUSIONS: In this cohort, totally MIE IL showed significantly less severe peri-operative morbidity than MIE 3-hole, but similar rates of serious pulmonary complications and anastomotic leaks. These findings confirm the safety of minimally invasive Ivor Lewis esophagectomies for esophageal cancer when oncologically and clinically appropriate. Minimally invasive McKeown esophagectomy remains a satisfactory and appropriate option when clinically indicated

Završna obrada zakaljenih zupčanika pomoću kubično borovih nitridnih (KBN) oštrica

The paper presents some results of investigation of finish machining of hardened bearing surfaces of cylindrical gear wheels. Finish machining has been performed with wedges of defined geometry made of CBN. The presented investigation results are related mainly to the wear processes of the cutting wedges. Additional results of quality examination of finish machined gear wheels have been presented, too.Rad prikazuje rezultate istraživanja završne obrade zakaljenih površina cilindričnih zupčanika. Završna obrada se ostvaruje oštricama definirane geometrije izrađene iz KBN. Prikazani rezultati istraživanja odnose se uglavnom na process trošenja reznih oštrica. Dodatno su prikazani rezultati ispitivanja kvalitete obrađene površine zupčanika

The Limits of Democracy: A Comparative Analysis of Democratic Backsliding in Syria and Tunisia After the Arab Spring

Fourteen years ago, the Middle East was shaken by widespread protests against authoritarian regimes, driven primarily by a lack of economic opportunities for citizens. These protests, spanning six Arab countries, held aspirations of ushering in change, reform, and democracy in the region. Today, however, the region appears more fractured, unsafe, and susceptible to radicalization compared to the onset of the Arab Spring in 2010. The present geopolitics and disillusionment in the Middle East raise essential questions for the world that this paper aims to answer. What are the factors leading to the decline of democracy following the initial spark of the Arab Spring? How can the U.S. adapt and adjust its policy approach given the rise of authoritarianism following the Arab Spring? Through a qualitative approach implementing expert interviews and descriptive data, this paper concludes that the Sunni/Shiite divide, unequipped government, the rise in fundamentalism, economic collapse, and inconsistent U.S. foreign policy were essential factors in extinguishing the flame of the Arab Spring

Enhancing Humoral Responses Against HIV Envelope Trimers via Nanoparticle Delivery with Stabilized Synthetic Liposomes

An HIV vaccine capable of eliciting durable neutralizing antibody responses continues to be an important unmet need. Multivalent nanoparticles displaying a high density of envelope trimers may be promising immunogen forms to elicit strong and durable humoral responses to HIV, but critical particle design criteria remain to be fully defined. To this end, we developed strategies to covalently anchor a stabilized gp140 trimer, BG505 MD39, on the surfaces of synthetic liposomes to study the effects of trimer density and vesicle stability on vaccine-elicited humoral responses in mice. CryoEM imaging revealed homogeneously distributed and oriented MD39 on the surface of liposomes irrespective of particle size, lipid composition, and conjugation strategy. Immunization with covalent MD39-coupled liposomes led to increased germinal center and antigen-specific T follicular helper cell responses and significantly higher avidity serum MD39-specific IgG responses compared to immunization with soluble MD39 trimers. A priming immunization with liposomal-MD39 was important for elicitation of high avidity antibody responses, regardless of whether booster immunizations were administered with either soluble or particulate trimers. The stability of trimer anchoring to liposomes was critical for these effects, as germinal center and output antibody responses were further increased by liposome compositions incorporating sphingomyelin that exhibited high in vitro stability in the presence of serum. Together these data highlight key liposome design features for optimizing humoral immunity to lipid nanoparticle immunogens.National Institute of Allergy and Infectious Diseases (U.S.) (Award UM1AI100663)National Institutes of Health (U.S.) (Award P01-AI104715)National Institutes of Health (U.S.) (Award P01-AI048240)National Cancer Institute (U.S.) (Grant P30-CA14051

Load capacity of hardened gear wheels machined with cubic boron nitride (CBN) wedges

The paper presents the results of exploitation examination of gear wheels with hardened bearing surface. The gears under investigation have been finish machined by the method elaborated by the author, with a tool possessing wedges made of CBN (cubic boron nitride). The symptoms of tooth surface wear having arisen during operation on the test rig with power loop. Assessment of the gear wheels’ capacity of carrying loads under EHL (ElastoHydrodynamic Lubrication) conditions has been performed

Medical Students’ Knowledge, Attitude, Practice, and Perceived Barriers Towards Medical Research: A Cross-Sectional Study

Background. Medical research and innovation are essential for the growth of medical education and healthcare system. Medical students should be taught in a research-informed environment, which allows them to make better clinical decisions and enhances their scientific output. Aim. The purpose of this study was to evaluate medical students’ knowledge, attitude, practice, and perceived barriers towards undergraduate medical research in the Kurdistan region of Iraq. Methods. This cross-sectional study, which was carried out between October 2022 and April 2023, included medical students from seven medical colleges in the Kurdistan region of Iraq. The survey comprised 19 questions, categorized into five sections, and delivered to students using the Google form platform. Results. A total of 363 medical students from seven medical colleges in the Kurdistan Region of Iraq were enrolled in this study. The sex ratio was about equal. The mean age was 20.6 (± 1.7 SD) years. Study participants demonstrated a low level of knowledge of research fundamentals, with an average correct response rate of 37.7%, as only 8.8% of participants answered all questions correctly. Three-fifths (61.5%) of participants believed research should be integrated into the curriculum, while about one-third (27%) of our study participants viewed research as an additional burden. Nearly one-third (34%) of students had participated in a research project before. Conclusions. In our study, we found that students in clinical stages aged 21 or older and those with prior research experience showed significantly higher knowledge levels. Research participation was associated with a more favorable attitude. The vast majority of our students expressed a keen interest in participating in research projects. Students identified lack of time and deficient research skills as the most prominent barriers hindering their active participation in research

Synthetic Nanoparticles for Vaccines and Immunotherapy

The immune system plays a critical role in our health. No other component of human physiology plays a decisive role in as diverse an array of maladies, from deadly diseases with which we are all familiar to equally terrible esoteric conditions: HIV, malaria, pneumococcal and influenza infections; cancer; atherosclerosis; autoimmune diseases such as lupus, diabetes, and multiple sclerosis. The importance of understanding the function of the immune system and learning how to modulate immunity to protect against or treat disease thus cannot be overstated. Fortunately, we are entering an exciting era where the science of immunology is defining pathways for the rational manipulation of the immune system at the cellular and molecular level, and this understanding is leading to dramatic advances in the clinic that are transforming the future of medicine.1,2 These initial advances are being made primarily through biologic drugs– recombinant proteins (especially antibodies) or patient-derived cell therapies– but exciting data from preclinical studies suggest that a marriage of approaches based in biotechnology with the materials science and chemistry of nanomaterials, especially nanoparticles, could enable more effective and safer immune engineering strategies. This review will examine these nanoparticle-based strategies to immune modulation in detail, and discuss the promise and outstanding challenges facing the field of immune engineering from a chemical biology/materials engineering perspectiveNational Institutes of Health (U.S.) (Grants AI111860, CA174795, CA172164, AI091693, and AI095109)United States. Department of Defense (W911NF-13-D-0001 and Awards W911NF-07-D-0004

Persistent Megalocystic Ovary Following in Vitro Fertilization in a Postpartum Patient with Polycystic Ovarian Syndrome

SummaryObjectiveOvarian hyperstimulation syndrome (OHSS) is more severe when pregnancy occurs, as the developing pregnancy produces human chorionic gonadotropin, which stimulates the ovary's persistent growth. If no pregnancy occurs, the syndrome will typically resolve within 1 week. In a maintained pregnancy, slow resolution of symptoms usually occurs over 1-2 months.Case ReportA 31-year-old woman, gravida 2, para 1, aborta 1, with polycystic ovary syndrome underwent in vitro fertilization (IVF) with clomiphene citrate and follicle-stimulating hormone/gonadotropin releasing hormone-antagonist stimulation. During transvaginal oocyte retrieval, enlarged bilateral ovaries were noted. She had an episode of OHSS after IVF/embryo transfer, for which paracentesis was performed three times. Pregnancy was achieved. Throughout antenatal examinations, bilateral ovaries were enlarged. She delivered a healthy baby by cesarean section at term. However, 1 month after delivery, the bilateral ovary had not shrunk, and levels of tumor markers CA125 and CA199 were 50.84 and 41.34 U/mL, respectively. At laparotomy for suspected malignancy, both adnexae formed “kissing ovaries”, which were multinodulated with yellow serous fluid. Specimens from wedge resection submitted for frozen section showed a benign ovarian cyst. The final pathology report showed bilateral follicle cysts.ConclusionWith the increasing use of gonadotropins in the management of infertility, ovarian enlargement secondary to hyperstimulation is common. Generally, symptoms appear between the 6th and 13th weeks of pregnancy and disappear thereafter. The hyperstimulated ovary often subsides after the first trimester. This case is unusual as the megalocystic ovary persisted after delivery. To the best of our knowledge, we report the first case of enlarged bilateral ovaries persisting 2 months after delivery

Wandering minds in attention-deficit/hyperactivity disorder and borderline personality disorder

Attention-deficit/hyperactivity Disorder (ADHD) and borderline personality disorder (BPD) have overlapping symptoms. We proposed that excessive spontaneous mind wandering (MW-S) might reflect a component of psychopathology that distinguishes ADHD from BPD. Using a questionnaire measure of MW-S and an experience sampling method, we investigated MW-S in daily life, in 28 ADHD, 19 BPD, 22 comorbid ADHD+BPD, and 29 control females. The clinical groups reported heightened frequency and intensity of MW-S compared to controls, but no differences from each other. When controlling for depression and anxiety, significant differences only persisted between controls and ADHD, who also showed elevated intensity of MW-S compared to BPD and comorbid ADHD+BPD. We found no MW-S instability differences amongst clinical cases as well as cases versus controls. Negative content of MW-S was higher in BPD and comorbid ADHD+BPD compared to controls, with no differences between ADHD and controls. When controlling for depression/anxiety, the differences between BPD and comorbid ADHD+BPD and controls dissipated. MW-S is a trans-diagnostic process present in both ADHD and BPD. Yet, the underlying mechanisms of this experience may be driven by anxiety/depression in BPD but reflect a core process in ADHD