In vitro antifungal and physicochemical properties of polymerized acrylic resin containing strontium-modified phosphate-based glass.

Acrylic resins are widely used as the main components in removable orthodontic appliances. However, poor oral hygiene and maintenance of orthodontic appliances provide a suitable environment for the growth of pathogenic microorganisms. In this study, strontium-modified phosphate-based glass (Sr-PBG) was added to orthodontic acrylic resin at 0% (control), 3.75%, 7.5%, and 15% by weight to evaluate the surface and physicochemical properties of the novel material and its in vitro antifungal effect against Candida albicans (C. albicans). Surface microhardness and contact angle did not vary between the control and 3.75% Sr-PBG groups (p > 0.05), and the flexural strength was lower in the experimental groups than in the control group (p < 0.05), but no difference was found with Sr-PBG content (p > 0.05). All experimental groups showed an antifungal effect at 24 and 48 h compared to that in the control group (p < 0.05). This study demonstrated that 3.75% Sr-PBG exhibits antifungal effects against C. albicans along with suitable physicochemical properties, which may help to minimize the risk of adverse effects associated with harmful microbial living on removable orthodontic appliances and promote the use of various materials.

Adsorption Capacity and Desorption Efficiency of Activated Carbon for Odors from Medical Waste.

Five types of odor-emitting exhaust gases from medical waste were selected, and their adsorption capacity and desorption efficiency were investigated using activated carbon. The selected gases included polar gases (hydrogen sulfide (H2S) and ammonia (NH3)) and non-polar gases (acetaldehyde (AA), methyl mercaptan (MM), and trimethylamine (TMA))). Commercial activated carbon with a specific surface area of 2276 m2/g was used as the adsorbent. For the removal of odor from medical waste, we investigated: (1) the effective adsorption capacity of a single gas (<1 ppm), (2) the effect of the adsorbed NH3 gas concentration and flow rate, and (3) the desorption rate using NH3 gas. The values of the effective adsorption capacity of the single gas were in the following order: H2S < NH3 < AA < MM < TMA, at 0.2, 4.2, 6.3, 6.6, and 35.7 mg/g, respectively. The results indicate that polar gases have a lower effective adsorption capacity than that of non-polar gases, and that the size of the gas molecules and effective adsorption capacity exhibit a proportional relationship. The effective adsorption performance of NH3 gas showed an increasing trend with NH3 concentration. Therefore, securing optimal conditions for adsorption/desorption is imperative for the highly efficient removal of odor from medical waste.

Multilevel Reset Dependent Set of a Biodegradable Memristor with Physically Transient.

The electronic device, with its biocompatibility, biodegradability, and ease of fabrication process, shows great potential to embed into health monitoring and hardware data security systems. Herein, polyvinylpyrrolidone (PVP) biopolymer is presented as an active layer, electrochemically active magnesium (Mg) as a metal electrode, and chitosan-based substrate (CHS) to fabricate biocompatible and biodegradable physically transient neuromorphic device (W/Mg/PVP/Mg/CHS). The I-V curve of device is non-volatile bipolar in nature and shows a unique compliance-induced multilevel RESET-dependent-SET behavior while sweeping the compliance current from a few microamperes to milliamperes. Non-volatile and stable switching properties are demonstrated with a long endurance test (100 sweeps) and retention time of over 104  s. The physically transient memristor (PTM) has remarkably high dynamic RON /ROFF (ON/OFF state resistance) ratio (106 Ω), and when placed in deionized (DI) water, the device is observed to completely dissolve within 10 min. The pulse transient measurements demonstrate the neuromorphic computation capabilities of the device in the form of excitatory post synaptic current (EPSC), potentiation, depression, and learning behavior, which resemble the biological function of neurons. The results demonstrate the potential of W/Mg/PVP/Mg/CHS device for use in future healthcare and physically transient electronics.

Structure-Guided Generation of a Redox-Independent Blue Fluorescent Protein from mBFP.

Fluorescent proteins, such as the green fluorescent protein, are used for detection of cellular components and events. However, green fluorescent protein and its derivatives have limited usage under anaerobic conditions and require a long maturation time. On the other hand, the NADPH-dependent blue fluorescent protein (BFP) without oxidative modification of residues is instantly functional in both aerobic and anaerobic systems. BFP proteins belong to a short-chain dehydrogenase/reductase (SDR) protein family, and their fluorescent property changes with reaction time in the presence of a substrate. With the aim of developing a better fluorescent reporter independent of redox state, we elucidated the crystal structure of a tetrameric mBFP from soil metagenomes with and without NADPH. Apart from the previously known regions, structure-guided mutational studies have identified several residues that contribute to the fluorescence of mBFP, including two aromatic residues (F97 and Y157) near the nicotinamide moiety of the bound NADPH. A single histidine mutation at Y157 (Y157H) has conferred more stabilized, time-independent fluorescence even in the presence of substrates. Furthermore, we discovered another SDR protein that can also emit blue fluorescence. These results open a new possibility for the development of BFP as a stable cellular reporter for widespread use, independent of subcellular environments.