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2D SnO2 disks with excellent purity and crystallinity were synthesized through a low cost, facile hydrothermal process and were characterized in terms of their morphological, structural, optical and electrochemical properties. The 2D disk-like morphology of synthesized SnO2 presented the average thickness of ∼1 μm and possessed the typical rutile tetragonal phase for the SnO2 with preferred growth along (100) plane. As-synthesized SnO2 disks were used for the fabrication of gas sensors for reducing gases like H2, CO, and C3H8. With the optimized temperature at 400 °C, the as-synthesized SnO2 electrode expressed the gas responses of 14.7, 9.3 and 8.1 for H2, CO, and C3H8, respectively. Contrary, the reasonable response times of 4 s, 3 s, and 8 s and the recovery times of 331 s, 201 s, and 252 s were recorded for H2, CO, and C3H8 gases, respectively. The DFT studies conducted herein suggest that the adsorbed oxygenated species act as a primary redox mediator for gas sensing reaction between reductive gases like H2, CO and C3H8, and SnO2 sensor. From DFT analysis, a very low heat of adsorption (≤0.2 eV) estimated which suggested the physisorption of the H2 molecules on the surface of the sensing material (i.e. SnO2). In contrast, the deposited oxygen atom forms strong chemical bonds with O2c and O3c sites. The oxygen atom bonded to O2c site control the conductivity of the sensor better than the O3c sites.

Electrochemical biosensing relies on electron transport on the electrode surface. However, the limited functional area of the two-dimensional electrode prevents the qualitative breakthrough in the efficiency of electron transfer. Here, a three-dimensional electron transporter was constructed to improve the efficiency of electron transfer by using an interface-immobilized DNA hydrogel. A three-dimensional pure DNA hydrogel is constructed and used as a scaffold for electron transfer. Then, an electron mediator is embedded in the DNA hydrogel through intercalative binding, and DNAzyme with intrinsic peroxidase-like activity is introduced at the node of the hydrogel scaffold to fabricate an electrochemical biosensor. The conduction of the electron mediator in the scaffold enables the acquisition of long-distance DNAzyme catalytic signals, thereby overcoming the limitation of two-dimensional electrodes. This three-dimensional electron transporter is significant for enriching the toolbox of electrochemical biosensing and can provide potential support for the development of highly sensitive biosensors.

High-quality polymeric composite films containing Congo red dye and PVA were prepared using the casting technique. The proposed Cr-doped PVA composites were examined using XRD, UV–visible optical, dielectric, and optical limiting effect techniques. The XRD patterns of CR-doped PVA composite films display diffraction peaks, which belong to CR organic dye. There was a broadening and reduction of the initial peak intensity in polymer composite films at higher doping concentrations. The band edge of CR: PVA composites reduced with a massive shift from 4.63 eV to 1.86 e, where Congo red controls the energy bandgap of the PVA polymer. Dielectric permittivity diminishes with increasing the frequency and achieves constant values at higher frequencies through the relation between the electric dipole and the electric field differences. Increasing the percentage ratio of the CR doping enhances the electrical conductivity and dielectric permittivities due to the large size of the CR molecules. The strong optical limiting of the CR-doped PVA composites is determined using different laser sources of 632.8 and 532 nm wavelengths. The amazing obtained results imply that CR: PVA composite films are very significant for applying large-scale CUT-OFF laser filters for medical optical and electronic device systems.

Chemical sensors fabricated from porous silicon (PSi) for liquid organic analytes (ethanol, acetonitrile, methanol and acetone) are demonstrated, with an emphasis on the impact of the Ag electrical contact placement on sensor performance. Sensors with front side contact display larger shift in capacitance response (2–3 times more sensitive) compared to the backside sensor design as the solvents immediately interact with the pore openings before infiltration. Much slower response time (7–30 min range) for front side vs. (50–200 s scale range) for backside configuration is observed. Both sensor designs exhibit excellent solvent infiltration-evaporation reversible response, indicating no chemical reaction or surface modification occurred. The response time was in the order of ethanol > acetonitrile > methanol > acetone, which correlates well with the solvent vapor pressure. The capacitance shift in both sensor devices is likely related to the interface interaction, revealing a closer correlation with the dipole moments of solvents. This is supported by the photoluminescence quenching upon exposure to organic solvents, with a relative intensity decrease tracks with the dipole moment. The sensitivity remains sufficiently high during the repeated use, with excellent storage stability for backside contact. This comparative study suggests the viability of the current sensor structure and design particularly with backside contact for sensing of various chemical analytes with notably sensitivity and extremely rapid response. Keywords: Meso-porous silicon, Electrical sensor, Capacitance, Photoluminescence, Organic solvents

A tetraphenylethylene (TPE) derivative (N,N-dimethyl-N′-(4-(1,2,2-triphenylvinyl)phenyl)acetimidamide, TPE-amidine) was designed and synthesized, and used to prepare visible CO2 chemosensors, TPE-amidine-L (liquid) and TPE-amidine-S (solid). The hydrophilicity of TPE-amidine thoroughly changed because of the unique reversible reaction between the amidine group and CO2, which controlled the molecular aggregation extent in water by CO2. Combining with the well-known aggregate-induced emission effect, the highly selective CO2 chemosensor TPE-amidine-L was developed, which has the lowest CO2 detection limit of 24.6 ppm compared with other reported CO2 chemosensors, and can be regenerated within 10 s by adding triethylamine. With the aim of being safer and more convenient to use, a polyacrylamide hydrogel containing TPE-amidine was prepared as a renewable CO2 sensing “tape” (TPE-amidine-S). The flexibility, adhesivity, CO2 sensitivity and reversibility of the “tape” is systematically investigated, showing great potential for “on-site” and “real-time” CO2 detection in practical applications.

Menyfah Q Alanazi,1–3 Mahmoud Salam,2–4 Fulwah Y Alqahtani,5 Anwar E Ahmed,2,3 Abdullah Q Alenaze,6 Majed Al-Jeraisy,2,3,7Majed Al Salamah,8 Fadilah S Aleanizy,5 Daham Al Daham,2,3 Saad Al Obaidy,7 Fatma Al-Shareef,9 Abdulaziz H Alsaggabi,1 Mohammed H Al-Assiri2,3 1Drug Policy and Economics Center, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs, Riyadh, Saudi Arabia; 2King Abdullah International Medical Research Center, Riyadh, Saudi Arabia; 3King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia; 4Hariri School of Nursing, American University of Beirut, Beirut, Lebanon; 5Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia; 6Ishbilia Primary Health Care, Ministry of Health, Riyadh, Saudi Arabia; 7Pharmaceutical Care Service, Ministry of National Guard-Health Affairs, Riyadh, Saudi Arabia; 8Emergency Department, Ministry of National Guard-Health Affairs, Riyadh, Saudi Arabia; 9Saudi Medication Safety Centre, Ministry of National Guard-Health Affairs, Riyadh, Saudi ArabiaCorrespondence: Menyfah Q AlanaziDrug Policy and Economics Center, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs, P.O. Box 22390, Riyadh 11426, Saudi ArabiaTel +966 11 801 1111Email menefah@gmail.comBackground: Antibiotic prescriptions at emergency departments (ED) could be a primary contributing factor to the overuse of antimicrobial agents and subsequently antimicrobial resistance. The aim of this study was to describe the pattern of antibiotic prescriptions at an emergency department of a tertiary care hospital in Saudi Arabia.Methods: A cross-sectional study, based on a review of antibiotic prescriptions was conducted. All cases who visited the emergency department over a three-month period with a complaint of infection were analyzed in terms of patient characteristics (age, sex, infection type, and number of visits) and prescription characteristics (antibiotic category, spectrum, course and costs). The World Health Organization and International Network of Rational Use of Drugs prescribing indicators were presented. Descriptive and analytic statistics were applied.Results: A total of 36,069 ED visits were recorded during the study period, of which 45,770 drug prescriptions were prescribed, including 6,354 antibiotics. The average number of drugs per encounter was 1.26, while the percentage of encounters with a prescribed antibiotic was 17.6%. Among antibiotic prescriptions, the percentage of encounters with injection antibiotics was 15.2%. Almost 77% of antibiotics were prescribed by their generic names, and the percentage of antibiotics prescribed from the essential list was 100%.Conclusion: The average number of drugs per encounter in general and antibiotics per encounter in specific at this setting was lower than the standard value. However, the percentage of antibiotics prescribed by its generic name was less than optimal.Keywords: antibiotic, prescription, errors, prevalence, predictors, emergency

The slaughterhouse waste (SHW) contains high organics which makes SHW a feasible feedstock for anaerobic digestion (AD). The present study systematically assessed the microbiome response and biomethanation along with the production of volatile fatty acids (VFAs) and ammonia under 2%, 4%, 6%, and 8% (w v−1) loadings of SHW in AD. The optimum loading was 2% SHW which resulted in maximum biomethane production and VFAs consumption. A higher SHW concentration (4% and 6%) resulted in a prolonged lag-phase and decreased biomethane production. High VFAs (28.88 g L−1) and ammonia nitrogen (>4 g L−1) accumulation were observed at 8% SHW leading to permanent inhibition of biomethane and methanogenic archaea. An increase in ammonia and VFAs concentration, at 4% and 6% SHW loadings, shifted the methanogenic pathway from acetoclastic to hydrogenotrophic lead by Methanoculleus. Acetoclastic Methanosaeta (77.15%) dominated the reactors loaded with 2% SHW resulting in the highest biomethane production.

Background SARS-CoV-2 is associated with a severe inflammatory response contributing to respiratory and systemic manifestations, morbidity, and mortality in patients with coronavirus disease 2019 (COVID-19). Methods Tocilizumab (TCZ) efficacy on mortality and length of hospital stay was retrospectively evaluated in patients who received TCZ and compared with that in controls with a similar severity of COVID-19. The primary endpoint was survival probability on day 28. The secondary endpoints included survival at day 14 and length of hospital stay. Results Of the 148 patients included in the study, 62 received TCZ and standard of care, whereas 86 served as a control group and received only standard of care. The two groups were similar, although TCZ-treated patients were more likely to exhibit hypertension (46.7% vs. 29.8%), chronic kidney disease (14.5% vs. 1.1%), and high Charlson score (1.18 vs. 1.00; p = 0.006) and less likely to receive corticosteroid treatment (48.5% vs. 93.0%). TCZ was associated with lower mortality on both day 28 (16.1% vs. 37.2%, p = 0.004) and day 14 (9.7% vs. 24.4%, p = 0.022). The hospital stay was longer in the TCZ-treated than in the control group (15.6 ± 7.59 vs.17.7 ± 7.8 days, p = 0.103). Ten patients (16.0%) in the TCZ-treated group developed infections. Conclusion TCZ was associated with a lower likelihood of death despite resulting in higher infection rates and a non-significant longer hospital stay.

A voltammetric approach was developed for the selective and sensitive determination of hydrogen peroxide using Au plated porous silicon (PSi) nanopowder modified glassy carbon electrode (GCE). The AuNPs-PSi hybrid structure was synthesized via stain etching procedure followed by an immersion plating method to deposit AuNPs onto PSi via a simple galvanic displacement reaction with no external reducing agent to convert Au3+ to Au0. The as-fabricated AuNPs-PSi catalyst was successfully characterized by XRD, Raman, FTIR, XPS, SEM, TEM and EDS techniques. Well crystalline nature of the as-fabricated hybrid structure with AuNPs size ranging from 5 to 40 nm was observed. The specific surface area and total pore volume for both PSi and AuNPs plated PSi were evaluated using N2 adsorption isotherm technique. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were applied to investigate the catalytic efficiency of AuNPs-PSi modified electrode compared to pure PSi/GCE and unmodified GCE. The sensing performance of the active material modified GCE was thoroughly examined with linear sweep voltammetry (LSV) and square wave voltammetry (SWV) techniques. The AuNPs-PSi/GCE exhibited a remarkable linear dynamic range between 2.0 and 13.81 mM (for LSV) and 0.5–6.91 mM for (SWV) with high sensitivity and low detection limit of 10.65 μAmM−1cm−2 and 14.84 μM for LSV, whereas 10.41 μAmM−1cm−2 and 15.16 μM using SWV techniques, respectively. The fabricated sensor electrode showed excellent anti-interfering ability in the presence of several common biomolecules as well as demonstrated good operational stability and reproducibility with low relative standard deviation. Moreover, the modified electrode showed acceptable recovery of H2O2 in a real sample analysis. Thus, the developed AuNPs-PSi hybrid nanomaterial represents an excellent electrocatalyst for the efficient detection and quantification of H2O2 by the electrochemical approach.

The development of a simple, sensitive, and effective method for the analysis of circulating tumor cells (CTCs) is essential for cancer diagnosis and metastasis prediction. In this work, we have proposed an enzyme-free electrochemical method for specific capture, sensitive quantification, and efficient release of CTCs. To achieve this, the specific interaction between CTCs and the corresponding aptamer designed to be located in the identification probe (IP) will unfold the hairpin structure of IP. Consequently, IP will initiate a hybridization reaction to produce a duplex, which will further trigger the hybridization chain reaction (HCR) process to form a composite product of CTCs and double-stranded DNA polymers. Therefore, a significantly amplified signal readout can be obtained. Moreover, the composite product can be brought to the electrode surface by tetrahedral DNA nanostructures to achieve the purpose of capturing and quantifying CTCs. More significantly, these captured CTCs can be controlled released without compromising cell viability via a simple strand displacement reaction. Taking the breast cancer cell MCF-7 as a representative, the newly developed approach led to an ultralow detection limit of 3 cells mL-1, which is superior to several studies previously reported. The current method has also been demonstrated to analyze CTCs in human whole blood and hence revealed a great potential in the future.

Novel silver nanoparticles decorated porous silicon (AgNPs-PSi) was fabricated via stain etching of Si, followed by simple immersion plating of Ag and applied successfully for enhanced electro-oxidation and quantification of ascorbic acid (AA). The newly developed nanocomposite consists of mesoporous Si (