Unified Quantum Mechanical Picture for Confined Spinons in Dimerized and Frustrated Spin S=1/2 Chains

A quantum mechanical picture is presented to describe the behavior of confined spinons in a variety of S=1/2 chains. The confinement is due to dimerization and frustration and it manifests itselfas a nonlinear potential V(x)~ |x|^b, centered at chain ends (b <= 1) or produced by modulation kinks (b > 1). The calculation extends to weak or zero frustration some previous ideas valid for spinons in strongly frustrated spin chains. The local magnetization patterns of the confined spinons are calculated. A (minimum) enhancement of the local moments of about 11/3 over a single S=1/2 is found. Estimates for excitation energies and binding lengths are obtained.Comment: 11.5 pages, Revtex, 10 figures included, accepted by Euro. Phys. J. B final version including some changes, several references adde

Remarkable performance recovery in highly defective perovskite solar cells by photo-oxidation

Exposure to environmental factors is generally expected to cause degradation in perovskite films and solar cells. Herein, we show that films with certain defect profiles can display the opposite effect, healing upon exposure to oxygen under illumination. We tune the iodine content of methylammonium lead triiodide perovskite from understoichiometric to overstoichiometric and expose them to oxygen and light prior to the addition of the top layers of the device, thereby examining the defect dependence of their photooxidative response in the absence of storage-related chemical processes. The contrast between the photovoltaic properties of the cells with different defects is stark. Understoichiometric samples indeed degrade, demonstrating performance at 33% of their untreated counterparts, while stoichiometric samples maintain their performance levels. Surprisingly, overstoichiometric samples, which show low current density and strong reverse hysteresis when untreated, heal to maximum performance levels (the same as untreated, stoichiometric samples) upon the photooxidative treatment. A similar, albeit smaller-scale, effect is observed for triple cation and methylammonium-free compositions, demonstrating the general application of this treatment to state-of-the-art compositions. We examine the reasons behind this response by a suite of characterization techniques, finding that the performance changes coincide with microstructural decay at the crystal surface, reorientation of the bulk crystal structure for the understoichiometric cells, and a decrease in the iodine-to-lead ratio of all films. These results indicate that defect engineering is a powerful tool to manipulate the stability of perovskite solar cells

Semiresorbable biologic hybrid meshes for ventral abdominal hernia repair in potentially contaminated settings: lower risk of recurrence

In case of potential contamination, implantation of synthetic meshes in hernia and abdominal wall surgery is problematic due to a higher risk of mesh infection. As an alternative, a variety of different biologic meshes have been used. However, relevant data comparing outcome after implantation of these meshes are lacking. Between January 2012 and October 2021, biologic meshes were used for reconstruction of the abdominal wall in 71 patients with preoperative or intraoperative abdominal contamination. In this retrospective study, semiresorbable biologic hybrid meshes (BHM) and completely resorbable meshes (CRM) were compared and analyzed using a Castor EDC database. In 28 patients, semiresorbable biologic hybrid meshes were used; in 43 patients, completely resorbable meshes were used. Both groups showed no difference in age, gender, BMI, operation duration, hernia size and Charlson comorbidity index. The risk degree of surgical-site occurrences was graded according to the Ventral Hernia Working Group (VHWG) classification, and the median value was 3 (range 2–4) in the BHM group and 3 (range 2–4) in the CRM group. Hernia recurrence within 24 months after hernia repair was significantly lower in the BHM group (3.6% vs. 28.9%; p = 0.03), while postoperative complication rate, with respect to seromas in need of therapy (61.4% vs. 55.5%, p = 0.43) and operative revision (28.6% vs. 16.3%, p = 0.22) was not different in either group. Biologic hybrid meshes can be used safely in case of possible contamination. BHM seems to reduce the risk of hernia recurrence compared to completely resorbable biologic meshes, but this has to be investigated further

Long-term effects of preeclampsia on maternal cardiovascular health and postpartum utilization of primary care: an observational claims data study

Purpose: Preeclampsia occurs in up to 15% of pregnancies and constitutes a major risk factor for cardiovascular disease. This observational cohort study aimed to examine the association between preeclamptic pregnancies and cardiovascular outcomes as well as primary and specialized care utilization after delivery. Methods: Using statutory claims data we identified women with singleton live births between 2010 and 2017. Main outcomes included the occurrence of either hypertension or cardiovascular disease after one or more preeclamptic pregnancies, number of contacts to a general practitioner or cardiologist after delivery and prescribed antihypertensive medication. Data were analyzed using Cox proportional hazard regression models adjusted for maternal age, diabetes, dyslipidemia, and obesity. Results: The study cohort consisted of 181,574 women with 240,698 births. Women who experienced preeclampsia once had an increased risk for cardiovascular (hazard ratio, HR = 1.29) or hypertensive (HR = 4.13) events. In women affected by recurrent preeclampsia, risks were even higher to develop cardiovascular disease (HR = 1.53) or hypertension (HR = 6.01). In the following years after delivery, general practitioners were seen frequently, whereas cardiologists were consulted rarely (0.3 and 2.4%). Conclusion: Women affected by preeclampsia experience an increased risk of developing chronic hypertension and cardiovascular disease, especially those with recurrent preeclampsia. Future medical guidelines should take this potential risk into account

Confocal laser endomicroscopy is a new imaging modality for recognition of intramucosal bacteria in inflammatory bowel disease in vivo

Interaction of bacteria with the immune system within the intestinal mucosa plays a key role in the pathogenesis of inflammatory bowel disease (IBD). The aim of the current study was to develop a fluorescein-aided confocal laser endomicroscopy (CLE) method to visualise intramucosal enteric bacteria in vivo and to determine the involved mucosal area in the colon and ileum in patients with ulcerative colitis (UC) and Crohn's disease (CD)

Confocal endomicroscopy identifies loss of local barrier function in the duodenum of patients with Crohn's disease and ulcerative colitis

Background: Increased cell shedding with gap formation and local barrier dysfunction can be identified endomicroscopically in the terminal ileum of patients with inflammatory bowel disease. We aim to evaluate whether these changes are also present in the duodenum of patients with inflammatory bowel disease. Methods: Fifteen patients with Crohn's disease (CD), 10 patients with ulcerative colitis (UC), and 10 controls underwent fluorescein-aided confocal laser endomicroscopy (CLE). CLE was performed on macroscopically normal antral and duodenal (D1, D2, D3, D4) mucosa. Representative CLE images were prospectively analyzed. Images were scored for the number of epithelial gaps, cell shedding, and the degree of fluorescein leakage into the intestinal lumen. Results: Both CD and UC patients had significantly more epithelial gaps, epithelial cell shedding, and leakage of fluorescein into the duodenal lumen than controls. The degree of cell shedding and epithelial gap formation was similar in CD and UC patients. In all cases, macroscopic endoscopic appearances of the duodenum were normal, and conventional histological analysis showed a mild nonspecific duodenitis in 7 of 15 patients with CD. Patients with UC had a histologically normal duodenum. Gap formation, cell shedding, and fluorescein leakage was similar in CD with active compared with inactive disease, except for D2 shedding. Conclusions: CLE can detect epithelial damage and barrier loss in the duodenum of CD and UC patients that is not apparent on conventional endoscopy or histology. Copyright © 2014 Crohn's & Colitis Foundation of America, Inc

Initial characterisation of commercially available ELISA tests and the immune response of the clinically correlated SARS-CoV-2 biobank "SERO-BL-COVID-19" collected during the pandemic onset in Switzerland

Background To accurately measure seroprevalance in the population, both the expected immune response as well as the assay performances have to be well characterised. Here, we describe the collection and initial characterisation of a blood and saliva biobank obtained after the initial peak of the SARS-CoV-2 pandemic in Switzerland.Methods Two laboratory ELISAs measuring IgA & IgG (Euroimmun), and IgM & IgG (Epitope Diagnostics) were used to characterise the biobank collected from 349 re- and convalescent patients from the canton of Basel-Landschaft.Findings The antibody response in terms of recognized epitopes is diverse, especially in oligosymptomatic patients, while the average strength of the antibody response of the population does correlate with the severity of the disease at each time point.Interpretation The diverse immune response presents a challenge when conducting epidemiological studies as the used assays only detect ∼90% of the oligosymptomatic cases. This problem cannot be rectified by using more sensitive assay setting as they concomitantly reduce specificity.Funding Funding was obtained from the "Amt für Gesundheit" of the canton Basel-Landschaft, Switzerland.Competing Interest StatementThe authors have declared no competing interest.Funding StatementThis study was sponsored by Jurg Sommer, head of the Amt fur Gesundheit, and the logistics of the sample collection were provided by the crisis staff and the civil protection service of the canton Basel-Landschaft.Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:This study is part of the project COVID-19 in Baselland Investigation and Validation of Serological Diagnostic Assays and Epidemiological Study of Sars-CoV-2 specific Antibody Responses (SERO-BL-COVID-19) approved by the ethics board Ethikkommission Nordwest- und Zentralschweiz (EKNZ), Hebelstrasse 53, 4056 Basel representative of Swissethics under the number (2020-00816).All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesData are available upon reques