Multiplexed Gas Sensor: Fabrication Strategies, Recent Progress, and Challenges.

Due to miscellaneous toxic gases in the vicinity, there is a burgeoning need for advancement in the existing gas sensing technology not only for the survival of mankind but also for the industries based in various fields such as beverage, forestry, health care, environmental monitoring, agriculture, and military security. A gas sensor must be highly selective toward a specific gas in order to avoid incorrect signals while responding to nontarget gases. This may lead to complex scenarios depicting sensor defects, such as low selectivity and cross-sensitivity. Therefore, a multiplex gas sensor is required to address the problems of cross selectivity by combining different gas sensors, signal processing, and pattern recognition techniques along with the currently employed gas sensing technologies. The different sensing materials used in these sensor arrays will produce a unique response signal for developing a set of identifiers as the input that can be used to recognize a specific gas by its "fingerprint". This review provides a comprehensive review of chemiresistive-based multiplex gas sensors, including various fabrication strategies from expensive to low-cost techniques, advances in sensing materials, and a gist of various pattern recognition techniques used for both rigid and flexible gas sensor applications. Finally, the review assesses the current state-of-the-art in multiplex gas sensor technology and discusses various challenges for future research in this direction.

A review of cost-effective black silicon fabrication techniques and applications.

Ever since the discovery of black silicon, scientists around the world have been trying to come up with novel, cost-effective methods of utilizing this super material in a variety of different industries due to its remarkably low reflectivity and excellent electronic and optoelectronic properties. In this review, many of the most common methods of black silicon fabrication are exhibited, including metal-assisted chemical etching, reactive ion etching, and femto-second laser irradiation. Different nanostructured silicon surfaces are assessed based on their reflectivity and applicable properties in both the visible wavelength range and the infrared range. The most cost efficient technique for the mass production of black silicon is discussed, as well as some promising contender materials ready to replace silicon. Also, solar cell, IR photo-detector, and antibacterial applications are looked into, along with their respective challenges to date.

The effect of temporary closure and enhanced terminal disinfection using aerosolized hydrogen peroxide of an open-bay intensive care unit on the acquisition of extensively drug-resistant Acinetobacter baumannii.

BACKGROUND: At Makassed Hospital's open-bay intensive care unit (ICU), enhanced terminal disinfection (ETD) using hydrogen peroxide (H2O2) was performed without a predefined schedule in extensively-drug-resistant Acinetobacter baumannii (XDR-AB) outbreaks. In this study, we aimed to check for the value of the temporary closure of the ICU and the use of ETD with aerosolized H2O2 and Ag+ on minimizing the rate of XDR-AB acquisition in patients admitted to the ICU of our facility, which might consequently help us determine the optimal schedule for such procedure in this unit. METHODS: This is a retrospective medical file review of patients admitted to the ICU between January 2016 and May 2018. We divided this period into numerical weeks (NW) after each closure and ETD episode. Risk factors of acquisition (RFA) were determined by comparing the characteristics of patients who acquired XDR-AB to those who didn't. The proportion of patients residing in each NW was included in the RFA analysis. RESULTS: Out of 335 patients, 13% acquired XDR-AB. The overall incidence of XDR-AB acquisition was 14.6 cases/1000 patient days. RFA were XDR-AB contact pressure ≥ 3 days [Odds Ratio (OR) = 9.86, 95% Confidence Interval (CI) (3.65-26.64), P < 0.0001)], mechanical ventilation [OR = 4.99, 95%CI (1.76-14.15), P = 0.002)], and having a wound [OR = 3.72, 95%CI (0.99-13.96), P = 0.05)]. Patients who stayed during NW 7,11 and 14 were at risk of acquisition where the odds significantly increased by 6.5, 9.7 and 14.4 folds respectively (P = 0.03,0.01, and 0.01, respectively). We considered NW 7 as the most suitable time for temporary closure of the ICU and ETD with aerosolized H2O2. CONCLUSION: Contact pressure, mechanical ventilation, and presence of a wound were RFA of XDR-AB. Temporary closure of the ICU with ETD using aerosolized H2O2 decreased the rate of XDR-AB acquisition, yet this effect fades away with time. The ETD was shown to be most efficiently done when repeated every 7 calendar weeks in our open-bay ICU as part of a prevention bundle.

Topology assisted self-organization of colloidal nanoparticles: application to 2D large-scale nanomastering.

Our aim was to elaborate a novel method for fully controllable large-scale nanopatterning. We investigated the influence of the surface topology, i.e., a pre-pattern of hydrogen silsesquioxane (HSQ) posts, on the self-organization of polystyrene beads (PS) dispersed over a large surface. Depending on the post size and spacing, long-range ordering of self-organized polystyrene beads is observed wherein guide posts were used leading to single crystal structure. Topology assisted self-organization has proved to be one of the solutions to obtain large-scale ordering. Besides post size and spacing, the colloidal concentration and the nature of solvent were found to have a significant effect on the self-organization of the PS beads. Scanning electron microscope and associated Fourier transform analysis were used to characterize the morphology of the ordered surfaces. Finally, the production of silicon molds is demonstrated by using the beads as a template for dry etching.