Early Failure Research Articles

Genotype-phenotype correlation in recessive DNAJB4 myopathy.

Protein aggregate myopathies can result from pathogenic variants in genes encoding protein chaperones. DNAJB4 is a cochaperone belonging to the heat shock protein-40 (HSP40) family and plays a vital role in cellular proteostasis. Recessive loss-of-function variants in DNAJB4 cause myopathy with early respiratory failure and spinal rigidity, presenting from infancy to adulthood. This study investigated the broader clinical and genetic spectrum of DNAJB4 myopathy. In this study, we performed whole-exome sequencing on seven patients with early respiratory failure of unknown genetic etiology. We identified five distinct pathogenic variants in DNAJB4 in five unrelated families of diverse ethnic backgrounds: three loss-of-function variants (c.547C > T, p.R183*; c.775C > T, p.R259*; an exon 2 deletion) and two missense variants (c.105G > C, p.K35N; c.181A > G, p.R61G). All patients were homozygous. All affected individuals exhibited early respiratory failure, and patients from three families had rigid spine syndrome with axial weakness in proportion to appendicular weakness. Additional symptoms included dysphagia, ankle contractures, scoliosis, neck stiffness, and cardiac dysfunction. Notably, J-domain missense variants were associated with a more severe phenotype, including an earlier age of onset and a higher mortality rate, suggesting a strong genotype-phenotype correlation. Consistent with a loss of function, the nonsense variants presented decreased stability. In contrast, the missense variants exhibited normal or increased stability but behaved as loss-of-function variants in yeast complementation and TDP-43 disaggregation assays. Our findings suggest that DNAJB4 is an emerging cause of myopathy with rigid spine syndrome of variable age of onset and severity. This diagnosis should be considered in individuals presenting with suggestive symptoms, particularly if they exhibit neck stiffness during infancy or experience respiratory failure in adults without significant limb muscle weakness. Missense variants in the J-domain may predict a more severe phenotype.

Prevalence of unexpected intraoperative cultures (UPIC) in revision total knee arthroplasty (TKA) and risk of periprosthetic joint infection (PJI).

Prevalence of unexpected positive intraoperative cultures (UPIC) in revision total knee arthroplasty (TKA) is reported to be 8.32% with largely varying findings in individual studies (5.92-62.07%) due to a heterogeneity in preoperative diagnostic work-up and diagnostic criteria for periprosthetic joint infection (PJI). When diagnosed as unsuspected PJI, re-revision rate is reported to be as high as 18.45% compared to 2.94% in patients with UPIC classified as contamination (p = 0.0237). We performed a monocentric retrospective analysis of revision TKA surgery to determine prevalence of UPIC, risk of developing a subsequent PJI and re-revision rate after 24 months compared to those without UPIC. All presumed aseptic total knee revision procedures from 2008 until 2017 were retrospectively reviewed. Single stage femorotibial revisions of TKA with at least 3 intraoperative cultures and a minimum follow-up of 24 months were included, whereas partial revisions or revisions from unicompartimental knee prosthesis to TKA were excluded. Demographic data were collected as well as initial reason for revision, preoperative aspiration results, micro-organism identified and postoperative antibiotics' administration. Primary outcome was survival rate after 24 months with differentiation based on UPIC interpretation: sterile, contamination, unsuspected PJI. Of 256 included cases, 75 (29.3%) were found to have at least 1 UPIC during revision surgery, 72% of whom a single UPIC was found. Thirty-four cases (13.28%) were interpreted as unsuspected PJI and therefore treated with antibiotics. In total, 13 of the 256 patients (5.08%) had to be re-revised during follow-up with 7 PJI (2.73%), none of them developing reinfection defined as PJI with the same microorganism. A statistically significant trend towards earlier failure in the unsuspected PJI group compared to the contaminant group was not observed. However, a higher incidence of re-revisions attributed to septic reasons was noted in the former group. Presence of UPIC in presumed aseptic revision TKA does not correlate with a lower survival rate, but a higher incidence of subsequent PJI was observed in cases interpreted as unsuspected PJI.

Assessing bonding and debonding properties of Evotherm modified bitumen with natural aggregates using surface free energy approach

ABSTRACT An incongruous pairing of aggregates and bitumen can result in early pavement failures such as stripping, raveling, and fatigue cracking. Surface free energy (SFE) assessments of aggregates and bitumen offer a means to evaluate the compatibility of the aggregate-bitumen system. It is important to emphasise that the SFE of both bitumen and aggregates significantly influences the determination of a compatible aggregate-bitumen combination. In this study, the moisture damage resistance of unmodified bitumen types (VG20, VG40) and modified bitumen types (PMB40, CRMB60) incorporating chemical-based warm mix asphalt (WMA) additives, specifically Evotherm, was investigated. The SFE approach was utilised to gain insights into their performance. In the laboratory, the static contact angle and SFE parameters of both unmodified and modified bitumen, with and without Evotherm, were determined using the Sessile drop method. Five different aggregate types were employed to calculate SFE performance parameters. Subsequently, the SFE performance parameter of forty combinations of aggregates and bitumen was calculated. As part of the assessment of moisture damage resistance, the compatibility ratio (CR) parameter was estimated using the dry adhesion energy, bitumen cohesion energy, wet adhesion energy, and wettability of different combinations of bitumen with aggregates. From the result, Evotherm addition to base bitumen (excluding VG20) significantly improved CR across various aggregates. Notable increases were observed for VG40, PMB40, and CRMB60 after Evotherm addition, with improvements of 66.67%, 48.48%, and 64.54% respectively for basalt aggregate. PMB40+EM with basalt aggregate exhibited the highest CR and Tensile Strength Ratio (TSR), suggesting superior moisture damage resistance compared to other bitumen combinations.

Changing Ideological Regimes: CEO Succession with A Shift in Political Ideology and New CEO Early Departure

AbstractWe examine the effects of CEO succession coupled with a change in political ideology – when a conservative CEO is replaced by a liberal CEO or vice versa. We argue that in such CEO transitions, the new CEOs must alter their predecessors’ ideological imprints to imbue strategic leadership with their own values, which increases their executive job demands in the critical early years of their tenure and raises the likelihood of their early departure. We also suggest that this relationship is moderated by two strategic leadership interface (SLI) factors that influence the executive job demands these new CEOs face: (a) the retention of the ideologically incongruent predecessor as board chair, and (b) the ideological fit between the new CEO and the incumbent executive team. We first test our framework using data from 2286 CEO successions in S&P 1500 firms. We then conduct an experimental study to ensure causality and confirm executive job demands as a mediating mechanism underlying the relationship. Overall, our study advances the disruption theory of succession by shedding light on the deeply held mechanisms that lead to early failure in CEO transitions.

Post-Vasectomy Semen Analysis: What's All the Fuss about?

Vasectomy is a reliable male contraceptive method with a success rate exceeding 98%. Despite its efficacy, vasectomy is not foolproof, with potential early and late failures requiring careful postoperative monitoring via post-vasectomy semen analysis (PVSA). Published guidelines emphasize the necessity of conducting PVSA to ensure clinical sterility. Despite these clear guidelines, discrepancies in adherence and interpretation persist, with significant mismatches between guidelines and actual practice. Recent shifts in societal attitudes toward reproductive autonomy, spurred by significant political events and socioeconomic factors, have increased vasectomy rates, particularly among younger, childless men. This demographic change calls for enhanced PVSA compliance and clear communication about the non-immediate contraceptive effect of vasectomy. Home test kits have emerged as a convenient, though not always reliable, method for conducting PVSAs, which may require reevaluation in clinical practice. Given the variations across clinical guidelines and the challenges in achieving consistent PVSA outcomes, further research is needed to harmonize PVSA protocols across different health systems. PVSA is typically conducted between 8 and 16 weeks post-vasectomy, depending on the surgeon's preference. Success is confirmed when a fresh, uncentrifuged sample exhibits either azoospermia, rare non-motile sperm (RNMS), or fewer than 100,000 non-motile sperm per milliliter. This effort will ensure that both patients and practitioners can rely on vasectomy as a safe and effective form of contraception. Effective patient counseling and strategic follow-up are crucial when it comes to managing expectations and ensuring compliance with post-vasectomy protocols, thereby minimizing the risk of unintended pregnancies post-procedure.

Estrogen Receptor Beta Agonist Influences Presynaptic NMDA Receptor Distribution in the Paraventricular Hypothalamic Nucleus Following Hypertension in a Mouse Model of Perimenopause.

Women become susceptible to hypertension as they transition to menopause (i.e., perimenopause); however, the underlying mechanisms are unclear. Animal studies using an accelerated ovarian failure (AOF) model of peri-menopause (peri-AOF) demonstrate that peri-AOF hypertension is associated with increased postsynaptic NMDA receptor plasticity in the paraventricular hypothalamic nucleus (PVN), a brain area critical for blood pressure regulation. However, recent evidence indicates that presynaptic NMDA receptors also play a role in neural plasticity. Here, using immuno-electron microscopy, we examine the influence of peri-AOF hypertension on the subcellular distribution of the essential NMDA GluN1 receptor subunit in PVN axon terminals in peri-AOF and in male mice. Hypertension was produced by 14-day slow-pressor angiotensin II (AngII) infusion. The involvement of estrogen signaling was investigated by co-administering an estrogen receptor beta (ERß) agonist. Although AngII induced hypertension in both peri-AOF and male mice, peri-AOF females showed higher cytoplasmic GluN1 levels. In peri-AOF females, activation of ERß blocked hypertension and increased plasmalemmal GluN1 in axon terminals. In contrast, stimulation of ERß did not inhibit hypertension or influence presynaptic GluN1 localization in males. These results indicate that sex-dependent recruitment of presynaptic NMDA receptors in the PVN is influenced by ERß signaling in mice during early ovarian failure.

Fanconi anemia diagnosed by genetic testing

Background : Fanconi anemia (FA) is a rare genetic disorder inherited in an autosomal recessive manner. The clinical phenotype varies depending on the involvement of different genes. Major physical abnormalities mainly affect the limbs and spine.. Methods/Observation : We report the case of an 11-year-old girl from a first-degree consanguineous marriage. The classic triad of short stature, malformation syndrome and early bone marrow failure suggested AF, which was confirmed by the detection of significant chromosomal instability after culture with Mitomycin C, compared with a normal control. Conclusion : This case highlights the crucial role of cytogenetics in the diagnosis of Fanconi anemia and genetic counseling to improve the management of affected children and their families. Keywords : Fanconi anemia; chromosomal breaks; mitomycin C.

Comparative Analysis of Decision Tree and Random Forest Algorithms for Diabetes Prediction

Diabetes Mellitus is a long-term medical disorder marked by high blood glucose levels that raise the risk of early mortality and organ failure. It has become an increasing global health problem, so making an accurate and timely diagnosis is urgently necessary. This study aims to diagnose people with diabetes mellitus by utilizing prediction techniques in data mining using experimental research. The prediction stage for diagnosing diabetes consists of four stages: dataset collection, data pre-processing, data processing, and evaluation. Data was obtained from Electronic Health Records (EHRs), namely the public "Diabetes Prediction Dataset". The pre-processing stage involves data filtering, attribute conversion, and class selection. The data processing utilizes random forests and decision tree models for diabetes prediction. The models were evaluated using accuracy, precision, and recall metrics. The results showed that the Random Forest algorithm produced an accuracy value of 93.97%, precision of 99.88%, and recall of 66.56%, with a computational time of 16s. Meanwhile, the decision tree algorithm produces an accuracy value of 93.89%, precision of 98.73%, and recall of 66.88%, with a computation time of less than 1s. Based on these results, it can be concluded that the Decision Tree algorithm is more effective because the difference in accuracy, precision, and recall values produced by the two algorithms does not have significant differences. However, the Decision Tree algorithm has the advantage of using computational time more effectively, which is needed in detecting diabetes because it is related to someone's life.

Analysis of Fracture Reason of Transmission Shaft of Screw Drilling Tool in a Certain Well

Abstract During the drilling process of a certain well in an oil field, the transmission shaft of the screw drilling tool broke. According to research, the screw drilling tool is brand new and has been in use for only 63.5 hours, indicating early failure. The fracture of the transmission shaft of the screw drilling tool is flat and severely worn, and the fracture is located at the change in diameter. In order to analyze the causes of the tool’s failure and avoid similar accidents, this article conducted non-destructive testing, macroscopic fracture analysis, chemical composition analysis, tensile performance testing, Charpy impact testing, Brinell hardness testing, metallographic analysis, microscopic analysis, and a comprehensive analysis of the failed transmission shaft of the spiral drilling rig. Through a series of analyses, it is believed that this tool belongs to fatigue fracture. The main reason is the presence of quenching cracks in the matrix structure near the fracture surface, which does not comply with industry standards. At the same time, before the screw drilling tool was put into use in the well, the operator did not conduct a flaw detection on the transmission shaft body according to the standard, so that quenching cracks were not detected in advance. After entering the well, the transmission shaft undergoes rapid propagation of quenching cracks under variable load, ultimately leading to early fatigue failure. This article suggests that manufacturers optimize the heat treatment process of screw drilling tool transmission shafts to improve product quality and prevent quenching cracks from appearing in the body. At the same time, operators should strictly follow the standards for non-destructive testing to avoid drilling tools with quality issues from entering the well for use.

The impact of colectomy and restorative procedure on pouch function after ileo-pouch-anal anastomosis in ulcerative colitis. The icon fun study on behalf of the Italian Society of Colon and Rectal Surgery (SICCR) Inflammatory Bowel Diseases committee

BackgroundAvailable guidelines lack in indications on surgical standard in Ulcerative Colitis (UC) AimsTo determine the role of surgical strategies of colectomy and proctectomy with pouch-anal-anastomosis (IPAA) on functional outcomes in a nationwide population multicenter study. The secondary aims consisted of perioperative outcomes and complications. MethodsData on 379 patients who underwent total abdominal colectomy and proctectomy with ileo-pouch-anal-anastomosis (IPAA) with or without diverting ileostomy were retrospectively collected in a red cap multicenter-database searching for variables that could impact on pouch outcomes as cuffitis, pouchitis, anastomotic stenosis, pouch stenosis, failure or pathological Low-Anterior-Resection-Syndrome (LARS) score. ResultsMesocolic dissection sealing vessels at major trunks and from medial to lateral are associated with better outcomes. Laparoscopy is associated with lower rate of cuffitis over time (p = 0.028). Mesentery lengthening is associated with higher pouchitis rate (p = 0.015) and earlier failure (p < 0.0001). Hand-sewn IPAA results in early anastomotic stenosis (p = 0.00011). The Transanal-Transection and Single-Stapling Anastomosis (TTSS) showed to be protective against pouchitis. Extended dissection of adhesions correlates with lower rate of pouchitis-episodes (p = 0.0057). ConclusionsThe study highlights advantages of laparoscopy. New techniques such as TTSS promise further improvements. Mesentery lengthening correlates with high risk of pouch-failure and pouchitis, hand-sewn anastomosis increased risk of stenosis.

Intraoperative hypotension during critical phases of liver transplantation and its impact on acute kidney injury: a retrospective cohort study

IntroductionAcute Kidney Injury (AKI) following Liver Transplantation (LT) is associated with prolonged ICU and hospital stay, increased risk of chronic renal disease, and decreased graft survival. Intraoperative hypotension is a modifiable risk factor associated with postoperative AKI. We aimed to determine in which phase of LT hypotension has the strongest association with AKI: the anhepatic or neohepatic phase. MethodsThis retrospective cohort study included adult patients undergoing LT between January 2010 and June 2022. Exclusion criteria were re-do or combined transplantations, preoperative dialysis, and early graft failure or death. Primary outcome was AKI as defined by KDIGO. Hypotension was Mean Arterial Pressure (MAP) below predefined thresholds in minutes. Risk adjusted logistic regression analysis considered hypotension in 3 periods: the total procedure, anhepatic phase, and neohepatic phase. ResultsOur cohort included 1153 patients. The median MELD-NA score was 19 (IQR 11–28), and 412 (35.9%) were living-related donations. AKI occurred in 544 patients (47.2%). The unadjusted model showed an association with AKI for MAP < 60 mmHg (OR = 1.011 [1.0, 1.022], p = 0.047) and MAP < 55 mmHg (OR = 1.023 [1.002, 1.047], p = 0.040) in the anhepatic phase, and for MAP < 60 mmHg (OR = 1.032 [1.01, 1.056], p = 0.006) in the neohepatic phase. The adjusted model did not reach significance in the subgroups but did in the total procedure: MAP < 60 mmHg (OR = 1.005 [1.002, 1.008], p < 0.001) and MAP < 55 mmHg (OR = 1.008 [1.003–1.013], p = 0.004). ConclusionIntraoperative hypotension is independently associated with AKI following LT. This association is seen during the anhepatic phase. Maintaining MAP above 60 mmHg may improve kidney function after LT.

Usefulness of using the superficial temporal pedicle as the recipient site for microvascular anastomosis in facial reconstruction: A retrospective study of 94 cases

In cranio-cervico-facial reconstructive surgery, it is accepted that the use of free flaps is the treatment of choice. The multiple antecedents can place the surgeon in situations of vascular deserts. The aim of our study is to report and analyse our experience of the use of temporal vessels in primary and secondary reconstructive surgery. A retrospective study was conducted between 01/01/2010 and 31/03/2023. Patients who underwent cranio-cervico-facial reconstruction using free flaps, with use of the superficial temporal pedicle as the recipient site for the vascular anastomosis were included. Early and late complication and failure rates were analysed according to type of reconstruction, location and risk factors for free flap failure. A total of 94 patients underwent craniocervical-facial reconstruction using a free flap anastomosed to the superficial temporal pedicle (in primary or secondary situations). Ten patients underwent reconstruction of the upper third, 58 the middle third and 26 the lower third. With an overall complication rate of 28.7% (21.3% minor complications and 7.4% major complications). Our study proves the reliability of the superficial temporal pedicle, both in the primary situation (with a success rate of 93.9%) and in the secondary situation (with a success rate of 89.3%), as well as its versatility whatever the cranio-cervico-facial level to be reconstructed. This study demonstrates the value of preserving the superficial temporal pedicle in craniofacial reconstruction surgery. This is because it is a preferred recipient site for reconstructions of the upper and middle thirds in the primary situation or in the event of recourse.

Heart Activity Visualization in Embryos with Crown-Rump Length Shorter Than 5 mm and Its Role in Prediction of Early Pregnancy Failure in Patients of Recurrent Early Pregnancy Loss

Heart Activity Visualization in Embryos with Crown-Rump Length Shorter Than 5 mm and Its Role in Prediction of Early Pregnancy Failure in Patients of Recurrent Early Pregnancy Loss

Very High Early Failure Rate Following Primary Repair of Acute Extensor Mechanism Disruption After Total Knee Arthroplasty

BackgroundExtensor mechanism disruption is a devastating complication following total knee arthroplasty (TKA). Despite its morbidity, there is no consensus regarding the optimal treatment strategy. We aimed to determine the survivorship, clinical outcomes, and improvement in patient-reported outcome measures after primary repair of acute extensor mechanism disruptions following primary or revision TKA. MethodsA retrospective review identified 41 acute extensor mechanism disruptions (33 primary TKAs and eight revision TKAs) from 2015 to 2021. The study group was 56% women, the mean body mass index was 33, the mean age was 66 years, and the mean follow-up was 3 years. Extensor mechanism disruption occurred at the patellar tendon (n = 17), quadriceps tendon (n = 15), and patella (n = 9) at a mean of 10 months following TKA. Surgical management was primary repair (n = 30) or primary repair with augmentation (allograft or autograft) (n = 11). Kaplan-Meier analysis estimated survivorship. ResultsThe 2-year survivorship free from all-cause reoperation was 72 and 23% following primary and revision TKA, respectively (P = 0.013). The 2-year survivorship free from all-cause reoperation was 66% for primary repair versus 61% for primary repair with augmentation (P = 0.95). There were 17 (41%) patients who underwent reoperation, most commonly for rerupture (n = 4) in two primary repairs and two primary repairs with augmentation (P = 0.288). Revision TKA (P = 0.049) and increased time from disruption to repair (P = 0.039) were risk factors for reoperation. Neither did the mean extensor lag significantly improve nor did patients see improvement in their patient-reported outcome measures. ConclusionsAfter primary and revision TKA, acute extensor mechanism disruption treated with primary repair with or without augmentation had very poor early survivorship free from all-cause reoperation. Patients should be counseled appropriately, and alternative surgical techniques should be considered.

Aseptic failure of total hip arthroplasty as an early complication requiring revision surgery: a comprehensive literature review

Background: The undertaking of hip joint endoprosthesis surgery carries the inherent risk of complications. During the perioperative and early postoperative phases, septic complications take precedence, notably those associated with infection. Conversely, aseptic complications encompass issues unrelated to infection. Accurate risk stratification for complications following hip prosthesis implantation should be grounded in research adhering to the principles of Evidence-Based Medicine.Aim of the study: This paper aimed to present a critical literature review Material and methods: The literature review was conducted using international medical databases such as PubMed, Scopus, and PEDro. The review was based on criteria that included clinical studies and full-text publications published in English. The search period covered the last decade, spanning from 2014 to 2024.Results: The review highlights aseptic loosening and dislocation as the predominant causes of early THA failures. Addressing these complications requires a multifaceted approach, including patient education, meticulous surgical techniques, and robust postoperative rehabilitation programs. Future research should focus on improving implant materials and techniques to further reduce the incidence of aseptic failures. Dislocation and loosening of the hip joint prosthesis are direct reasons for qualifying the patient for revision surgery and reconstruction of the damaged prosthesis components. Individual biomechanical characteristics of the patient, genetic predispositions, obesity, or improper positioning of the prosthesis in relation to the limb axis are also potential risk factors for dislocation.Conclusions: Aseptic complications remain a significant challenge in THA. By understanding the causes and implementing effective preventative strategies, the incidence of early failures can be reduced, improving patient outcomes and prosthesis longevity. The gradual introduction of a well-planned and individualized rehabilitation program, along with the patient's adherence to treatment recommendations, is crucial for minimizing the risk of mechanical damage.

Outcomes of acetabular fractures.

Acetabular fractures are prognostic relevant fractures in terms of function and daily activities. Open reduction and internal fixation (ORIF) is still the gold-standard in treating these injuries. Over recent years, several reports are dealing with outcome evaluations but have the main disadvantage of combining several fracture types., Thus, it remains unclear to discuss a fracture-based prognosis. This analysis evaluated fracture-type specific results in terms of clinical and radiological outcome. Analyzing elementary fracture types, pure transverse and isolated posterior column fractures are associated with relevant functional impairments. Except for posterior column fractures all other elementary fracture types were associated with degenerative changes in nearly 20%. Anterior column fractures seems to be "forgiving fractures" as they are associated with the longest median time until hip joint failure occurs. In associated fracture-types T-shaped fractures are still demanding fractures with < 60% anatomic reductions and a high rate of functional impairments. All associated fracture types are associated with a relevant rate of secondary degeneration of the hip joint between 20 and 40% of patients. Early hip joint failure (THR, Femoral head necrosis, severe heterotopic ossification) within the 1st year is frequently seen in associated posterior column and posterior wall fractures, but with a relative good prognosis, if the joint survived the first year after ORIF. The highest survival rates of the hip joint is observed with ABC-fractures. Also, these fractures seem to be "forgiving fractures".

Progressive degradation behavior and mechanism of lithium-ion batteries subjected to minor deformation damage

Minor deformation damage poses a concealed threat to battery performance and safety. This study delves into the progressive degradation behavior and mechanisms of lithium-ion batteries under minor deformation damage induced by out-of-plane compression. The effects of varying initial state of charge and loading speed on battery degradation are also analyzed. It has been observed that a deformation damage degree as low as 3.1 % can cause a significant transient capacity reduction up to 6.3 %. More transient capacity reduction can occur at higher initial state of charge and loading speed. Additionally, the investigation reveals that the capacity decay rate between the normal cell and cells experiencing deformation damage degree of <4.7 % is almost similar, with a maximum difference of merely 1.887 mAh/cycle and a minimum difference of 0.001 mAh/cycle, both observed over 3000 cycles. Non-destructive and destructive analysis methods are used to investigate degradation behaviors of the cells experiencing minor deformation dagame. It is found that such progressive degradation is primarily driven by the loss of active lithium ions, followed by the loss of cathode and anode active materials. It is anticipated that the findings will offer theoretical underpinnings for advancements in battery damage assessment, early failure prediction, and facilitation of loss adjustment and compensation by insurance agencies.

Accelerated degradation of PET-based photovoltaic backsheets under UV and acetic acid exposure

Despite initially certified in qualification tests, photovoltaic (PV) backsheets and entire systems often experience catastrophic failures within a few years of field deployment. Understanding the factors contributing to these failures is challenging due to the complex service conditions and composition of PV systems. In this study, we investigated the synergistic effects of UV exposure (an external weathering factor) and acetic acid (HAc, an internal weathering factor) on the degradation of PV backsheets. Polyethylene terephthalate (PET)-based backsheets, commonly used in PV systems, were selected as model samples. Key failure modes, including yellowing and cracking, were compared between PET backsheets aged with UV exposure alone and those exposed to both UV and HAc. The results revealed that the presence of HAc significantly accelerated the failure process of PET samples compared to those aged with UV and air alone. This additional acceleration was mainly attributed to the potential formation of hydroxyl radicals produced by HAc under UV exposure, which facilitates the chain scission reaction and the formation of chromophores. Density functional theory (DFT) calculations were also conducted to understand the accelerated aging effects induced by hydroxyl radicals. Additionally, combining UV/HAc exposure with mechanical stress resulted in even more accelerated degradation. These findings suggest that novel accelerated aging methods could be developed to better simulate field conditions, assess early failure risks, and enhance the design of robust and reliable PV products.

The Association Between Pulmonary Vascular Resistance and Posttransplant Outcomes Differs by Left Ventricular Assist Device Status.

Elevated pulmonary vascular resistance (PVR) is a risk factor for mortality after heart transplantation (HT), but whether this association differs for patients with and without left ventricular assist device (LVAD) support before HT is unknown. We analyzed adult first-time HT recipients from the United Network for Organ Sharing (UNOS) registry transplanted between 2010 and 2021. We quantified the association between PVR and the outcomes of 30 day graft failure and 1 year mortality using multivariable logistic regression, stratified by LVAD support status at the time of HT. Pulmonary vascular resistance was modeled using restricted cubic splines to identify clinically relevant risk thresholds. We also examined the association with 10 year survival using multivariable Cox proportional hazards regression. For PVR values less than approximately 2 WU, higher PVR was independently associated with a higher risk of early graft failure (odds ratio [OR] = 1.58, 95% CI: 1.06-2.36) and a higher risk of 1 year mortality (OR = 1.32, 95% CI: 1.10-1.59) among LVAD patients only (interaction p = 0.023 and 0.03, respectively). However, for patients surviving at least 1 year, PVR was not associated with long-term mortality among either subgroup. Whether more aggressive reduction of PVR among HT candidates supported with LVADs can mitigate these risks requires further study.

Constant Stress-Partially Accelerated Life Tests of Vtub-Shaped Lifetime Distribution under Progressive Type II Censoring

In lifetime tests, the waiting time for items to fail may be long under usual use conditions, particularly when the products have high reliability. To reduce the cost of testing without sacrificing the quality of the data obtained, the products are exposed to higher stress levels than normal, which quickly causes early failures. Therefore, accelerated life testing is essential since it saves costs and time. This paper considers constant stress-partially accelerated life tests under progressive Type II censored samples. This is realized under the claim that the lifetime of products under usual use conditions follows Vtub-shaped lifetime distribution, which is also known as log-log distribution. The log–log distribution is highly significant and has several real-world applications since it has distinct shapes of its probability density function and hazard rate function. A graphical description of the log–log distribution is exhibited, including plots of the probability density function and hazard rate. The log–log density has different shapes, such as decreasing, unimodal, and approximately symmetric. Several mathematical properties, such as quantiles, probability weighted moments, incomplete moments, moments of residual life, and reversed residual life functions, and entropy of the log–log distribution, are discussed. In addition, the maximum likelihood and maximum product spacing methods are used to obtain the interval and point estimators of the acceleration factor, as well as the model parameters. A simulation study is employed to assess the implementation of the estimation approaches under censoring schemes and different sample sizes. Finally, to demonstrate the viability of the various approaches, two real data sets are investigated.