Geometry relaxation-mediated localization and delocalization of excitons in organic semiconductors: A quantum chemical study.

Photo-induced relaxation processes leading to excimer formations or other traps are in the focus of many investigations of optoelectronic materials because they severely affect the efficiencies of corresponding devices. Such relaxation effects comprise inter-monomer distortions in which the orientations of the monomer change with respect to each other, whereas intra-monomer distortions are variations in the geometry of single monomers. Such distortions are generally neglected in quantum chemical investigations of organic dye aggregates due to the accompanied high computational costs. In the present study, we investigate their relevance using perylene-bisimide dimers and diindenoperylene tetramers as model systems. Our calculations underline the importance of intra-monomer distortions on the shape of the potential energy surfaces as a function of the coupling between the monomers. The latter is shown to depend strongly on the electronic state under consideration. In particular, it differs between the first and second excited state of the aggregate. Additionally, the magnitude of the geometrical relaxation decreases if the exciton is delocalized over an increasing number of monomers. For the interpretation of the vibronic coupling model, pseudo-Jahn-Teller or Marcus theory can be employed. In the first part of this paper, we establish the accuracy of density functional theory-based approaches for the prediction of vibrationally resolved absorption spectra of organic semiconductors. These investigations underline the accuracy of those approaches although shortcomings become obvious as well. These calculations also indicate the strength of intra-monomer relaxation effects.

Contact killing and antimicrobial properties of copper.

With the emergence of antibiotic resistance, the interest for antimicrobial agents has recently increased again in public health. Copper was recognized in 2008 by the United States Environmental Protection Agency (EPA) as the first metallic antimicrobial agent. This led to many investigations of the various properties of copper as an antibacterial, antifungal and antiviral agent. This review summarizes the latest findings about 'contact killing', the mechanism of action of copper nanoparticles and the different ways micro-organisms develop resistance to copper.

Nanoscale Structure of the Oil-Water Interface.

X-ray reflectivity (XR) and atomistic molecular dynamics (MD) simulations, carried out to determine the structure of the oil-water interface, provide new insight into the simplest liquid-liquid interface. For several oils (hexane, dodecane, and hexadecane) the XR shows very good agreement with a monotonic interface-normal electron density profile (EDP) broadened only by capillary waves. Similar agreement is also found for an EDP including a sub-Å thick electron depletion layer separating the oil and the water. The XR and MD derived depletions are much smaller than reported for the interface between solid-supported hydrophobic monolayers and water.

Peri-conceptional obesogenic exposure induces sex-specific programming of disease susceptibilities in adult mouse offspring.

Vulnerability of the fetus upon maternal obesity can potentially occur during all developmental phases. We aimed at elaborating longer-term health outcomes of fetal overnutrition during the earliest stages of development. We utilized Naval Medical Research Institute (NMRI) mice to induce pre-conceptional and gestational obesity and followed offspring outcomes in the absence of any postnatal obesogenic influences. Male adult offspring developed overweight, insulin resistance, hyperleptinemia, hyperuricemia and hepatic steatosis; all these features were not observed in females. Instead, they showed impaired fasting glucose and a reduced fat mass and adipocyte size. Influences of the interaction of maternal diet∗sex concerned offspring genes involved in fatty liver disease, lipid droplet size regulation and fat mass expansion. These data suggest that a peri-conceptional obesogenic exposure is sufficient to shape offspring gene expression patterns and health outcomes in a sex- and organ-specific manner, indicating varying developmental vulnerabilities between sexes towards metabolic disease in response to maternal overnutrition.

Evaluation of a biofilm formation by Desulfovibrio fairfieldensis on titanium implants.

UNLABELLED: The aim of this study was to assess the capabilities of Desulfovibrio fairfieldensis to colonize the grade 4 titanium coupons (modSLA) used in dental implants. The effect of ampicillin, which is known to be a poorly penetrating agent in the matrix biofilm, was also compared with planktonic and sessile cells. The modSLA colonization by bacteria in KNO3 (0.05 mol l(-1)) and culture media (DSM 63 and fetal bovine serum) was determined by direct cell counts and field emission electronic microscopy. The surface of titanium (Ti) coupons was characterized by scanning electron microscopy and by Raman spectroscopy. Cells, mainly located in surface pores of modSLA coupons, appeared to be wrapped in a polymeric-like structure. The initial apparent rates of adhesion varied from 3 × 10(6) to 30 × 10(6) cells cm(-2) h(-1), and a plateau was reached at 1 day, regardless of the incubation medium. No cells have significantly adhered to polished Ti, and a minority was found on massive Ti. Finally, cells trapped on the modSLA surface were not lysed by ampicillin contrary to planktonic cells. Des. fairfieldensis is therefore able to colonize the rough surface of modSLA implant through a physical trapping in the microporosity of the surface, where they can produce a biofilm-like structure to improve their resistance to ampicillin. SIGNIFICANCE AND IMPACT OF THE STUDY: Desulfovibrio fairfieldensis is one of the most relevant sulphate-reducing bacteria of the human oral cavity suspected to be involved in peri-implantitis and implant corrosion. This study demonstrates for the first time that Des. fairfieldensis is able to initiate the formation of a biofilm-like structure on the microstructured titanium coupons used in dental implants and that it improves its resistance to antibiotic treatment. It gives new insight to understand the capacity of this opportunistic pathogen to colonize implant surfaces and to resist to biocide treatments.

The usefulness of transient elastography in the assessment of patients with HBeAg-negative chronic hepatitis B virus infection.

Histological severity is often mandatory for the management of HBeAg-negative chronic HBV patients. We evaluated the performance of transient elastography (TE) in this setting. We included 357 untreated HBeAg-negative patients with ≥ 1 reliable liver stiffness measurement (LSM-kPa) by TE: 182 inactive carriers with HBV-DNA < 2000 (n = 139) or 2000-19 999 IU/mL (n = 43) and 175 patients with chronic hepatitis B (CHB). In carriers, HBV-DNA > 2000 and/or LSM > 6.5 were considered as biopsy indications. LSMs did not differ between carriers with low and high viremia, but were lower in carriers than in patients with CHB (5.8 ± 1.7 vs 9.0 ± 5.6, P < 0.001) offering moderate differentiation between these two groups (AUROC: 0.705). LSMs did not change significantly in carriers after 16 (12-24) months. In carriers with a liver biopsy, Ishak's staging scores were similar between cased with low and high viremia but higher in cases with LSM > 6.5 than ≤ 6.5 kPa. Moderate fibrosis (stages: 2-3) was detected in 0/10 carriers with only HBV-DNA > 2000 IU/mL, 2/10 (20%) carriers with only LSM > 6.5 and 5/10 (50%) carriers with both HBV-DNA > 2000 and LSM > 6.5 (P = 0.009). In patients with CHB, LSMs correlated significantly with grading and staging scores and offered excellent accuracy for ≥ moderate, ≥ severe fibrosis or cirrhosis (AUROC ≥ 0.919-0.950). TE can be helpful for the noninvasive assessment of HBeAg-negative chronic HBV patients. In conclusion, LSMs offer excellent accuracy for fibrosis severity in HBeAg-negative patients with CHB and can identify carriers with high risk of moderate fibrosis, which may be present in up to 35% of carriers with LSM > 6.5 kPa and 50% of carriers with LSM > 6.5 kPa and HBV-DNA > 2000 IU/mL.

Cirrhosis but not neutropenia is associated with the development of infection in patients with chronic hepatitis C undergoing treatment with pegylated interferon-alpha and ribavirin.

Peginterferon-alpha (PegIFNa) frequently causes neutropenia, mainly due to bone marrow suppression. The aim of this study was to explore factors that are associated with infections during antiviral treatment. We analysed data from 275 chronic hepatitis C (CHC) patients with compensated liver disease who underwent 318 courses of PegIFNa and ribavirin. Neutropenia was defined as neutrophils <1000 cells/µL. Mean leucocytes count significantly decreased from baseline to treatment nadir (7081 ± 2182 vs 3293 ± 1331 cells/µL, P < 0.001), while neutropenia was observed in 32% during treatment. Thirty-one infections were observed. The incidence rate for infection was assessed at 1.46 infections per 100 person-months of therapy. The hazard rate for infection did not correlate with the neutrophils' nadir or the decrease in white blood cells. In multivariate Cox's regression analysis, cirrhosis was the only factor that was significantly associated with the occurrence of infection. Our data show that the development of bacterial infections during treatment with PegIFNa and ribavirin in patients with compensated CHC is not associated with reduction or the nadir of white cells or neutrophil counts. Baseline cirrhosis is the only factor related with infection during treatment. The common practice of dose adjustment or discontinuation of interferon should be revised; careful assessment of liver damage before therapy and close monitoring during therapy are essential in all patients receiving interferon-based regimes, to minimize the detrimental consequences of infections.

Pseudorotational epitaxy of self-assembled octadecyltrichlorosilane monolayers on sapphire (0001).

The structure of octadecyltrichlorosilane self-assembled monolayers (SAMs) on sapphire (0001) was studied by Å-resolution surface-specific x-ray scattering methods. The monolayer was found to consist of three sublayers where the outermost layer corresponds to vertically oriented, closely packed alkyl tails. Laterally, the monolayer is hexagonally packed and exhibits pseudorotational epitaxy to the sapphire, manifested by a broad scattering peak at zero relative azimuthal rotation, with long powderlike tails. The lattice mismatch of ∼ 1%-3% to the sapphire's and the different length scale introduced by the lateral Si-O-Si bonding prohibit positional epitaxy. However, the substrate induces an intriguing increase in the crystalline coherence length of the SAM's powderlike crystallites when rotationally aligned with the sapphire's lattice. The increase correlates well with the rotational dependence of the separation of corresponding substrate-monolayer lattice sites.

High-resolution tomography study of the porosity of three restorative resin composites.

OBJECTIVES: The aim of this study was to analyze the porosity of three photopolymerizable resin composites: one high-viscous resin composite (Filtek™ P60®, 3 M™ ESPE™), one moderate-viscosity resin composite (Grandio®, VOCO™), and one low-viscous resin composite (Filtek™ Supreme XTE®, 3 M™ ESPE™). MATERIALS AND METHODS: A total of 36 cylindrical samples with a height of 2 mm and a diameter of 2 mm were prepared using PTFE molds. Eighteen cylinders were prepared by two incremental applications of 1 mm into the molds, then polymerized (group 1). For the other 18 samples (group 2), the first increment was polymerized before the second addition was made. The average porosity percentage and the average porosity volume were evaluated by high-resolution tomography (Nanotom M® - Phoenix X-Ray(TM), Wunstorf, Germany). The impact of incremental applications in terms of porosity was also evaluated. RESULTS: Irrespective of the protocol used, the low viscous material presented an average porosity percentage and an average porosity volume significantly greater than those of the other materials. Incremental application (group 2 samples) led to an increase in the average porosity percentage and volume irrespective of the material compared to the group 1 samples. CONCLUSIONS: High-resolution tomography appeared to be a particularly suitable tool for studying the porosity of resin composites. The viscosity and the handling of these materials seemed to be influential factors on their porosity. CLINICAL RELEVANCE: The presence of porosities in dental resin composites remains an objective reality, especially with low-viscous resin composites. Since the intrinsic porosity of the materials can be neither controlled nor modified by the operator, rigorous and iterative clinical protocols still remain the best way to limit inclusion of porosities in the resin composites.

Staged abdominal wall reconstruction in the setting of complex gastrointestinal reconstruction.

PURPOSE: Literature on one- versus two-staged abdominal wall reconstruction (AWR) with complex gastrointestinal reconstruction (GIR) is limited to single-arm case series with a focus on patients who complete all planned stages. Herein, we describe our experience with both one- and two-staged approaches to AWR/GIR, with attention to those who did not complete both intended stages. METHODS: A retrospective review of prospectively collected data was conducted to identify patients who underwent a one- or two-stage approach to GIR/AWR from 2013 to 2020. The one-stage approach included GIR and definitive sublay mesh herniorrhaphy. The two-stage approach included Stage 1 (S1)-GIR and non-definitive herniorrhaphy and Stage 2 (S2)-definitive sublay mesh herniorrhaphy. RESULTS: Fifty-four patients underwent GIR/AWR: 20 (37.0%) underwent a planned 1-stage operation while 34 (63.0%) underwent S1 of a planned 2-stage approach. Patients assigned to the 2-stage approach were more likely to be smokers, have a history of mesh infection, have an enterocutaneous fistula, and a contaminated wound class (p<0.05). Of the 34 patients who underwent S1, 12 (35.3%) completed S2 during the mean follow-up period of 44 months while 22 (64.7%) did not complete S2. Of these, 10 (45.5%) developed hernia recurrence but did not undergo S2 secondary to elective nonoperative management (40%), pending preoperative optimization (30%), additional complex GIR (10%), hernia-related incarceration requiring emergent surgery (10%), or unrelated death (10%). No differences in outcome including SSI, SSO, readmission, and recurrence were noted between the 12 patients who completed the two-stage approach and the 20 patients who completed a one-stage approach, despite increased risk factors for complications in the 2-stage group (p>0.05). CONCLUSION: Planned two-stage operations for GIR/AWR may distribute operative complexity and post-operative morbidity into separate surgical interventions. However, many patients may never undergo the intended definitive S2 herniorrhaphy. Future evaluation of 1- versus 2-stage GIR/AWR is needed to clarify indications for each approach. This work must also consider the frequent deviations from intended clinical course demonstrated in this study.