Charge trapping and detrapping in polymeric materials: Trapping parameters

Space charge formation in polymeric materials can cause some serious concern for design engineers as the electric field may severely be distorted, leading to part of the material being overstressed. This may result in material degradation and possibly premature failure at the worst. It is therefore important to understand charge generation, trapping, and detrapping processes in the material. Trap depths and density of trapping states in materials are important as they are potentially related to microstructure of the material. Changes in these parameters may reflect the aging taken place in the material. In the present paper, characteristics of charge trapping and detrapping in low density polyethylene (LDPE) under dc electric field have been investigated using the pulsed electroacoustic (PEA) technique. A simple trapping and detrapping model based on two trapping levels has been used to qualitatively explain the observation. Numerical simulation based on the above model has been carried out to extract parameters related to trapping characteristics in the material. It has been found that the space charge decaying during the first few hundred seconds corresponding to the fast changing part of the slope was trapped with the shallow trap depth 0.88 eV, with trap density 1.47 × 1020 m-3 in the sample volume measured. At the same time, the space charge that decays at longer time corresponding to the slower part of the slope was trapped with the deep trap depth 1.01 eV, with its trap density 3.54 × 1018 m-3. The results also indicate that trap depths and density of both shallow and deep traps may be used as aging markers as changes in the material will certainly affect trapping characteristics in terms of trap depth and density

Baseline elevated Lp-PLA2 is associated with increased risk for re-stenosis after stent placement

BACKGROUND: Lipoprotein associated phospholipase A2 (Lp-PLA2) is a novel biomarker for cardiovascular risk prediction. Whether increased Lp-PLA2 level is associated with re-stenosis after stent-placement is unclear. METHODS: Totally 326 participants eligible for stent-placement were enrolled and divided into two groups according to baseline Lp-PLA2 levels (named normal and elevated groups). Baseline characteristics and clinical outcomes were compared between normal and elevated groups. The relationships between Lp-PLA2 and other risk factors with re-stenosis were evaluated. RESULTS: Only the between-group difference of Lp-PLA2 was significant (123.2 ± 33.6 ng/mL vs 336.8 ± 85.4 ng/mL, P < 0.001) while other demographic and clinical characteristics between these two groups were comparable. Approximately 55.1% and 58.5% of participants in normal and elevated groups presented with acute coronary syndrome, and the percentage of tri-vessels stenoses was significantly higher in elevated group (40.8% vs 32.1%, P = 0.016). Nearly 96.0% and 94.0% of participants in normal and elevated Lp-PLA2 groups were placed with drug-eluting stents, and the others were with bare-metal stents. After 1 year’s follow-up, the incidence of clinical end-points was comparable (13.3% vs 15.4%, P = 0.172). Nevertheless, the incidence of re-stenosis was marginally higher in elevated Lp-PLA2 group (8.5% versus 4.6%, P = 0.047). With multivariate analysis, after adjustment for other risk factors, Lp-PLA2 remained an independent predictor for re-stenosis with a hazard ratio of 1.140. No synergistic effect between Lp-PLA2 and other risk factors for re-stenosis was found. CONCLUSION: Increased Lp-PLA2 level is associated with an increased risk of re-stenosis. Lp-PLA2 assessment may be useful in predicting subjects who are at increased risk for re-stenosis

PD-1 blockade and radiotherapy combination for advanced Epstein-Barr virus-associated intrahepatic cholangiocarcinoma: a case report and literature review

Advanced intrahepatic cholangiocarcinoma (ICC) is a rare malignant tumor of biliary epithelial cells, known for its extremely unfavorable prognosis. In the absence of intervention, patients typically survive for less than 5 months. Current guidelines from the Chinese Society of Clinical Oncology (CSCO), National Comprehensive Cancer Network (NCCN), and European Society for Medical Oncology (ESMO) recommend chemotherapy-based systemic therapy as the standard treatment for advanced ICC. However, the first-line regimen, consisting of gemcitabine in combination with cisplatin, generally results in a median survival of approximately one year, which is considered suboptimal. Significant progress has been made in radiotherapy techniques, molecular diagnostics, and tumor immune microenvironments. The integration of immune and radiation therapies has revolutionized treatment strategies for cholangiocarcinoma. Moreover, combined therapeutic regimens have shown promising results in improving survival rates among patients with advanced ICC. In this study, we present a case report of a 70-year-old male patient diagnosed with stage IV ICC, featuring metastases to the retroperitoneal, left adrenal, and left supraclavicular lymph nodes. The patient exhibited a high tumor mutational load, significant microsatellite instability, and hyper-expression of PD-L1 (90%), along with positive Epstein-Barr virus-encoded RNA (EBER). Pembrolizumab, a programmed cell death 1 (PD-1) inhibitor, was administered in conjunction with radiotherapy. As a result, considerable shrinkage and inactivation of the primary foci were observed, accompanied by the disappearance of metastases. Ultimately, the patient achieved complete remission and maintained progression-free survival for 41 months following the initial treatment. To the best of our knowledge, this represents the longest case of complete remission using a combination of immunotherapy and radiotherapy as a first-line regimen for the high tumor mutational load, microsatellite instability, and PD-L1 expression (90%) subtype of Epstein-Barr virus-associated ICC (EBVaICC). These findings suggest that the combination of PD-1 inhibitors with radiotherapy may serve as a promising therapeutic strategy for treating this particular cancer subtype

Prevalence of depressive tendencies among college students and the influence of attributional styles on depressive tendencies in the post-pandemic era

IntroductionDepression symptoms are prevalent globally, including China, with a notable impact on college students. This study aims to not only estimate the prevalence of depressive tendencies and attributional styles among college students in the post-pandemic era but also explore the relationship between the two factors. The findings of this study can provide new insights into early intervention and support services for individuals exhibiting tendencies toward depression.MethodsThe survey was administered to college students from various academic backgrounds at a specific university in southern Jiangxi Province by employing two scales to investigate depressive tendencies and attributional styles. Depressive tendency was evaluated using the Patient Health Questionnaire-9 (PHQ-9), while the attributional styles were assessed using the Multidimensional-Multiattributional Causality Scale (MMCS). Univariate analysis and multiple logistic regressions were conducted to identify the related factors of depressive tendency.ResultsA relatively high (48.9%) prevalence of depression among college students was found in this study. College students with higher grades (OR = 1.574, 95%CI: 1.369–1.810), profession of medicine and allied health sciences (OR = 1.779, 95%CI: 1.203–2.629), experiencing higher study stress (OR = 2.006, 95%CI: 1.601–2.514), and having poor physical condition (OR = 1.527, 95%CI: 1.247–1.869) were identified as risk factors for depressive tendency. The correlation between higher grades and increased learning pressure, coupled with poorer physical condition, heightens the vulnerability of college students to depression. Moreover, the more they attribute these experiences to achievement effort (OR = 0.897, 95%CI: 0.828–0.972), achievement ability (OR = 0.903, 95%CI: 0.838–0.972), and affiliation context (OR = 0.919, 95%CI: 0.860–0.982), the less likely they are to develop depression.ConclusionIn the group of college students, especially those in higher grades, profession of medicine and allied health sciences or experiencing high learning pressure and poor physical condition, emphasizing the significance of their mental well-being becomes crucial. Offering suitable support and assistance is essential. Additionally, fostering the cultivation of positive attributional and coping strategies by attributing difficulties to controllable factors and instilling a belief in their ability to overcome challenges can help reduce the risk of depression

2,2′-(Imino­dimethyl­ene)dibenz­imid­azol­ium bis­(perchlorate) methanol solvate

In the title compound, C16H17N5 2+·2ClO4 −·CH3OH, the dihedral angle between the two benzimidazolium ring systems is 34.6 (1)°. The anions and solvent mol­ecules are linked to the cation by N—H⋯O hydrogen bonds. In the crystal structure, the combination of N—H⋯O and O—H⋯O hydrogen bonds results in two-dimensional layers running parallel to the (010) plane; these are in turn linked by π–π inter­actions, forming a three-dimensional network

A case-control study on risk factors of breast cancer in China

Introduction: To screen the risk factors associated with breast cancer among Chinese women in order to evaluate the individual risk of developing breast cancer among women in China. Material and methods: A case-control study on 416 breast cancer patients and 1156 matched controls was conducted in 14 hospitals in 8 provinces of China in 2008. Controls were age- and region-matched to the cases. Clinicians conducted in-person interviews with the subjects to collect information on demographics and suspected risk factors for breast cancer that are known worldwide. Conditional logistic regression was used to derive odds ratios (OR) and 95% confidence intervals (CI) for the associations between risk factors and breast cancer. Results: Compared with matched controls, women with breast cancer were significantly more likely to have higher body mass index (BMI, OR = 4.07, 95% CI; 2.98-5.55), history of benign breast disease (BBD) biopsy (OR = 1.68, 95% CI; 1.19-2.38), older age of menarche (AOM) (OR = 1.41, 95% CI: 107-187), stress anticipation (SA), for grade 1-4, OR = 2.15, 95% CI; 1.26-3.66; for grade 5-9, OR = 3.48, 95% CI; 2.03-5.95) and menopause (OR = 2.22, 95% CI: 1.50-3.282) at the level of p &lt; 0.05. Family history of breast cancer (FHBC) in first-degree relatives (OR = 1.66, 95% CI; 0.77-3.59) and use of oral contraceptives (OC) (OR = 1.59, 95% CI; 0.83-3.05) were associated with an increased risk of breast cancer at the level of p &lt; 0.20. Conclusions: Our results showed that BMI, history of BBD biopsy, older AOM, SA and menopause were associated with increased risk of breast cancer among Chinese women. The findings derived from the study provided some suggestions for population-based prevention and control of breast cancer in China.Medicine, General &amp; InternalSCI(E)15ARTICLE2303-309