Soft contact lens extended wear affects corneal epithelial permeability: hypoxic or mechanical etiology?

Contact lens extended wear increases the permeability of epithelium to sodium fluorescein (P(dc)). The exact mechanism is not known. However, changes in P(dc) likely result from either corneal hypoxia or mechanical trauma, or both. We explored the effects of one-night continuous wear with either high- or low-Dk/t soft lenses on P(dc). The results show that corneal epithelial barrier function decreases significantly with both lens groups. We also observed that Asian eyes had higher P(dc) after overnight wear compared to non-Asian and that for both Asian and non-Asian eyes, the elimination of corneal hypoxia did not prevent changes in epithelial permeability.     

Double optical monitoring of dip coating with a time-varying refractive index

A brief overview of optical monitoring for vacuum and wet-bench film-deposition processes is presented. Interferometric and polarimetric measurements are combined with regard to simultaneous monitoring of refractive index and physical thickness in real time. Monitoring stability and accuracy are verified during dip coating with a transparent oil standard. This double optical technique is applied to dip coating with a multicomponent zirconyl chloride aqueous solution, whose resulting temporal refractive-index and physical-thickness curves indicate good reproducibility as well as significant sensitivity to changes of film-flow properties during the dip-coating process.     

Numerical and Experimental Investigation on the Self-Healing Potential of Interpenetrating Metal–Ceramic Composites

An interpenetrating metal ceramic composite (IMCC) has been investigated regarding the potential as well as the feasibility of self-healing. Triggered by heating, cracks in the damaged composite located mainly in the Al₂O₃ ceramic or at the interface could be filled and closed by the liquid AlSi10Mg metal alloy. This healing procedure promises to reduce stress concentrations at crack tips and to improve the mechanical properties compared to the predamaged composite. Two different numerical approaches have been introduced to investigate this assumption and the potential of self-healed IMCCs for a best case scenario: 1) A simple 2D model to analyze the reduction of stress concentrations in front of a crack tip within the ceramic due to healing and 2) a 3D model based on CT-scan reconstructed microstructures to study how macroscopic mechanical properties can be restored depending on the amount of predamage. Further, the self-healing approach has been investigated experimentally for the same composite. Despite the fact that experimental self-healing of the investigated IMCC is only moderately feasible so far, the study shows the great potential that can still be exploited in order to extend the service life time of IMCC engineering components.     

Fatty acid and oxylipin concentration differ markedly between different fetal bovine serums: A cautionary note

Fetal bovine serum (FBS) has been used as a universal supplement in cell culture for more than six decades. This includes the investigation of lipid and lipid mediator formation and biology. Little is known about the (polyunsaturated) fatty acid composition and their oxidation products in FBS. Therefore, we analyzed six different FBS purchased from three different companies regarding their fatty acid and oxylipin concentrations. We found pronounced differences in the fatty acid concentrations. Even two batches of “standardized” FBS batches from one company showed drastic differences (e.g., for eicosapentaenoic acid 5 ± 1 μM vs. 11 ± 1 μM). Oxylipin concentrations also markedly differ between the FBS lots. The highest differences were found for 12-lipoxygenase products (e.g., 12-hydroxyeicosatetraenoic acid free 21–87 nM and total 58–108 nM), probably due to inconsistent serum generation procedures. Our results indicate that for cell culture studies dealing with lipid metabolism, researchers should carefully characterize their used FBS to ensure reliability and reproducibility of study outcomes.     

Marginal Adaptation and Microbial Leakage at Conometric Prosthetic Connections for Implant-Supported Single Crowns: An In Vitro Investigation

Encouraging clinical results were reported on a novel cone-in-cone coupling for the fixation of dental implant-supported crowns (Acuris, Dentsply Sirona Implants, Mölndal, Sweden). However, the presence or absence of a microgap and a potential bacterial leakage at the conometric joint has not yet been investigated. A misfit and a resulting gap between the conometric components could potentially serve as a bacterial reservoir that promotes plaque formation, which in turn may lead to inflammation of the peri-implant tissues. Thus, a two-fold study set-up was designed in order to evaluate the bidirectional translocation of bacteria along conometrically seated single crowns. On conometric abutments filled with a culture suspension of anaerobic bacteria, the corresponding titanium nitride-coated (TiN) caps were fixed by friction. Each system was sterilized and immersed in culture medium to provide an optimal environment for microbial growth. Positive and negative controls were prepared. Specimens were stored in an anaerobic workstation, and total and viable bacterial counts were determined. Every 48 h, samples were taken from the reaction tubes to inoculate blood agar plates and to isolate bacterial DNA for quantification using qrt-PCR. In addition, one Acuris test system was subjected to scanning electron microscopy (SEM) to evaluate the precision of fit of the conometric coupling and marginal crown opening. Throughout the observational period of one week, blood agar plates of the specimens showed no viable bacterial growth. qrt-PCR, likewise, yielded a result approaching zero with an amount of about 0.53 × 10⁻⁴ µg/mL DNA. While the luting gap/marginal opening between the TiN-cap and the ceramic crown was within the clinically acceptable range, the SEM analysis failed to identify a measurable microgap at the cone-in-cone junction. Within the limits of the in-vitro study it can be concluded that the Acuris conometric interface does not allow for bacterial translocation under non-dynamic loading conditions.     

A review on critical assessment of advanced bioreactor options for sustainable hydrogen production

The utilization of fossil fuels causes adverse effects on the human and environment and the world is facing the depletion of these resources. The conventional technologies available for hydrogen production create greenhouse gases which cause a serious threat to the surroundings. Hence, there is a need to create a renewable and alternative technique for hydrogen production. The biological method acts as renewable technology to conventional technologies. For the present and future generations, the development of bioreactors may provide a sustainable route to meet cleaner hydrogen production. The conventional methods like reforming process, gasification process, thermochemical method, water electrolysis and photoelectrochemical method are not sustainable which emits toxic gases and requires a large amount of energy but in the application of bioreactors the cleaner fuel can be obtained and wastewater can be treated efficiently. The objectives of this review are to estimate the efficiency of reactors involving dark fermentation reactors (suspended and attached growth reactors), photobioreactors (tubular and flat plate reactors) and microbial electrolysis cell bioreactors along with their recent advancements in hydrogen production. This article also highlighted the comprehensive review about the substrate utilization, waste treatment, the principle of reactor process and recent process developments. Although several methods are available for hydrogen production, important and innovative discoveries and process configurations in pilot-scale are needed to estimate the potential of each bioreactor to provide sustainable and cleaner fuel production. Through this review, the present status of bioreactors in hydrogen production and their scale-up opportunities can be determined.     

Understanding continued smartwatch usage: the role of emotional as well as health and fitness factors

Electronic Markets - Smartwatches are the most popular wearable device and increasingly subject to empirical research. In recent years, the focus has shifted from revealing determinants of...