First principles study of 2D polar heterostructures.

Recently, two-dimensional (2D) heterostructures have attracted extensive attention in nanomaterials science. They have been successfully fabricated and applied to nanotechnology in many fields, such as nanoelectronics, solar cells, sensors, energy stores, quantum information, etc. The most common heterostructures are 2D-lateral heterostructure (LH) and 2D-vertical heterostructure (VH) where each of them exhibits unique features depending on the direction of assembly, i.e., along in-plane or out-of-plane direction. Beyond the van der Waals-VH which possess of van der Waals (vdW) interaction, there are other types of heterostructures made of 2D polar materials that possess different types of chemical bonding nature, e.g., chemical bonds with less (e.g., SiC monolayer) or more (e.g., GeC and SiGe monolayers) charge transfer between atoms, forming covalent bonds with a certain ionicity. The goal of this work focused on shedding light on the physical aspects of 2D LH and VH, constructed by such polar materials (e.g., , GeC, and SiGe monolayers). This work is a theoretical study by employing Density Functional Theory to unravel the unique physical properties of such heterostructures. Because an artificial strain will be induced by the lattice mismatch in building heterostructures, the effect of strain on the electronic properties of, and monolayers was first investigated. It was found that these monolayers can tolerate strain up to 8%, and such strain can induce modifications on the physical properties. Interestingly, it was found that and monolayers undergo a direct-indirect band gap transition; while, monolayer undergoes a metal-semimetal transition, which made them attractive candidates for building heterostructures. Second, a systematic study on the aspect of 2D polar-LH of and has been conducted. It was found that the synergistic effect of the lattice mismatch induced strain, the chemical bonding nature at the interface, and quantum confinement can lead to several interesting phenomena. For instance, their electronic properties can be modulated by tuning the domain size, the chemical bonding nature, and the designing of interface. Accordingly, a lateral spontaneous p-n junction triggered by the in-plane charge transfer was detected which implies the promising applications such as visible light photocatalyst. Third, the roles of the stacking species arrangement and the interlayer interactions (including vdW and electrostatic forces) on stabilizing the structure and modulating electronic properties of 2D polar-VH of were deeply studied. It was found that, in addition to the redistribution of the in-plane net-charge transfer, a net charge redistribution also occurs between layers and leads to a polarization in the interfacial region that induces a built-in electric field and helps to reduce the recombination of photogenerated electron-hole pairs

Tick-Borne Pathogens in Ticks and Blood Samples Collected from Camels in Riyadh Province, Saudi Arabia

Background and Objective: Domestic animals, including camels, in Saudi Arabia suffer from various diseases, among which tick-borne infections are important because they reduce the productivity of these animals. However, knowledge of tick-borne pathogens in camels in Saudi Arabia is very limited, so the aims of this study were to quantify the abundance and distribution of tick species infesting camels from different districts of Riyadh province and use molecular tools to detect tick-borne pathogens in both the ticks and blood samples. Materials and Methods: A total of 218 ticks were collected from 116 camels from the 5 districts of Riyadh. The ticks and camel blood samples were analyzed for Borrelia, Babesia and Theileria pathogens using conventional and real-time PCR. Results: The results showed that five different tick species were identified. Majority of the ticks were Hyalomma dromedarii (70.6%), which were collected from camels in all 5 districts. This was followed by Hyalomma impeltatum species (25.2%), which was again found in all the districts. The other species found were Hyalomma anatolicum, Haemaphysalis sp. and Rhipicephalus turanicus. The only one H. dromedarii tick was positive for Theileria sp. DNA. Although the sample size and the area of tick collection were limited, the data suggest that the prevalence of pathogens in the Riyadh province, Saudi Arabia is relatively low. Conclusion: The study provides useful preliminary data to inform future full-scale country-wide surveys

Evaluation of the performance of a composite profile at elevated temperatures using finite element and hybrid artificial intelligence techniques

It is very important to keep structures and constructional elements in service during and after exposure to elevated temperatures. Investigation of the structural behaviour of different components and structures at elevated temperatures is an approach to manipulate the serviceability of the structures during heat exposure. Channel connectors are widely used shear connectors not only for their appealing mechanical properties but also for their workability and cost-effective nature. In this study, a finite element (FE) evaluation was performed on an authentic composite model, and the behaviour of the channel shear connector at elevated temperature was examined. Furthermore, a novel hybrid intelligence algorithm based on a feature-selection trait with the incorporation of particle swarm optimization (PSO) and multi-layer perceptron (MLP) algorithms has been developed to predict the slip response of the channel. The hybrid intelligence algorithm that uses artificial neural networks is performed on derived data from the FE study. Finally, the obtained numerical results are compared with extreme learning machine (ELM) and radial basis function (RBF) results. The MLP-PSO represented dramatically accurate results for slip value prediction at elevated temperatures. The results proved the active presence of the channels, especially to improve the stiffness and loading capacity of the composite beam. Although the height enhances the ductility, stiffness is significantly reduced at elevated temperatures. According to the results, temperature, failure load, the height of connector and concrete block strength are the key governing parameters for composite floor design against high temperatures

Isolation and Characterization of Chi-like \u3ci\u3eSalmonella\u3c/i\u3e Bacteriophages Infecting Two \u3ci\u3eSalmonella enterica\u3c/i\u3e Serovars, Typhimurium and Enteritidis

Salmonella enterica Serovar Typhimurium and Salmonella enterica Serovar Enteritidis are well-known pathogens that cause foodborne diseases in humans. The emergence of antibiotic-resistant Salmonella serovars has caused serious public health problems worldwide. In this study, two lysogenic phages, STP11 and SEP13, were isolated from a wastewater treatment plant in Jeddah, KSA. Transmission electron microscopic images revealed that both phages are new members of the genus “Chivirus” within the family Siphoviridae. Both STP11 and SEP13 had a lysis time of 90 min with burst sizes of 176 and 170 PFU/cell, respectively. The two phages were thermostable (0 ◦C ≤ temperature \u3c 70 ◦C) and pH tolerant at 3 ≤ pH \u3c 11. STP11 showed lytic activity for approximately 42.8% (n = 6), while SEP13 showed against 35.7% (n = 5) of the tested bacterial strains. STP11 and STP13 have linear dsDNA genomes consisting of 58,890 bp and 58,893 bp nucleotide sequences with G + C contents of 57% and 56.5%, respectively. Bioinformatics analysis revealed that the genomes of phages STP11 and SEP13 contained 70 and 71 ORFs, respectively. No gene encoding tRNA was detected in their genome. Of the 70 putative ORFs of phage STP11, 27 (38.6%) were assigned to functional genes and 43 (61.4%) were annotated as hypothetical proteins. Similarly, 29 (40.8%) of the 71 putative ORFs of phage SEP13 were annotated as functional genes, whereas the remaining 42 (59.2%) were assigned as nonfunctional proteins. Phylogenetic analysis of the whole genome sequence demonstrated that the isolated phages are closely related to Chi-like Salmonella viruses

The impact of law enforcement on the dispensing antibiotics without prescription in Saudi Arabia : findings and implications

Background: Dispensing of antibiotics without a prescription (DAwP) has been widely practised in Saudi Arabia despite being illegal. This is a concern increasing AMR. In May 2018, the law and regulations were enforced including fines up to 100,000 SR (equivalent to US$26,666) and cancellation of licences. Consequently, we wanted to evaluate the impact. Methods: Mixed method study among 116 community pharmacies in two phases. Pre-law enforcement phase between December 2017 and March 2018 and post-law enforcement phase one year later. Each phase consisted of a cross-sectional questionnaire-based survey and a simulated client method (SCM). In the SCM, clients presented with either pharyngitis or urinary tract infections (UTI) with 3 levels: level 1 – SC asked for something to relieve the symptoms, level 2 – SC asked for something stronger if an antibiotic was not dispensed, level 3 – SC requested an antibiotic. In SCM for each phase, all 116 pharmacies were visited with at least one of the scenarios. Results: Before the law enforcement, 70.7% of community pharmacists reported DAwP was common. 96.6% and 87.7% of participating pharmacies dispensed antibiotics without a prescription for pharyngitis and UTI respectively. After law enforcement, only 12.9% of community pharmacists indicated that DAwP was common, with only 12.1% and 5.2% dispensing antibiotics without prescriptions for pharyngitis and UTI respectively and mostly after level 3. Conclusion: Law enforcement was effective. However, there is still further scope for improvement as community pharmacists are worried patients may go elsewhere if no antibiotic dispensed on request. This could include educational activities

Clinical and Serological Findings of COVID-19 Participants in the Region of Makkah, Saudi Arabia

Makkah in Saudi Arabia hosts the largest annual religious event in the world. Despite the many strict rules enacted, including Hajj cancellation, city lockdowns, and social distancing, the region has the second highest number of new COVID-19 cases in Saudi Arabia. Public health interventions that identify, isolate, and manage new cases could slow the infection rate. While RT-PCR is the current gold standard in SARS-CoV-2 identification, it yields false positive and negative results, which mandates the use of complementary serological tests. Here, we report the utility of serological assays during the acute phase of individuals with moderate and severe clinical manifestations of SARS-CoV-2 (COVID19). Fifty participants with positive RT-PCR results for SARS-CoV-2 were enrolled in this study. Following RT-PCR diagnosis, serum samples from the same participants were analyzed using in-house ELISA (IgM, IgA, and IgG) and microneutralization test (MNT) for the presence of antibodies. Of the 50 individuals analyzed, 43 (86%) showed a neutralizing antibody titer of >= 20. Univariate analysis with neutralizing antibodies as a dependent variable and the degree of disease severity and underlying medical conditions as fixed factors revealed that patients with no previous history of non-communicable diseases and moderate clinical manifestation had the strongest neutralizing antibody response "Mean: 561.11". Participants with severe symptoms and other underlying disorders, including deceased individuals, demonstrated the lowest neutralizing antibody response. Anti-spike protein antibody responses, as measured by ELISA, showed a statistically significant correlation with neutralizing antibodies. This reinforces the speculation that serological assays complement molecular testing for diagnostics; however, patients' previous medical history (anamnesis) should be considered in interpreting serological results.Peer reviewe

Clinical and Serological Findings of COVID-19 Participants in the Region of Makkah, Saudi Arabia

Makkah in Saudi Arabia hosts the largest annual religious event in the world. Despite the many strict rules enacted, including Hajj cancellation, city lockdowns, and social distancing, the region has the second highest number of new COVID-19 cases in Saudi Arabia. Public health interventions that identify, isolate, and manage new cases could slow the infection rate. While RT-PCR is the current gold standard in SARS-CoV-2 identification, it yields false positive and negative results, which mandates the use of complementary serological tests. Here, we report the utility of serological assays during the acute phase of individuals with moderate and severe clinical manifestations of SARS-CoV-2 (COVID19). Fifty participants with positive RT-PCR results for SARS-CoV-2 were enrolled in this study. Following RT-PCR diagnosis, serum samples from the same participants were analyzed using in-house ELISA (IgM, IgA, and IgG) and microneutralization test (MNT) for the presence of antibodies. Of the 50 individuals analyzed, 43 (86%) showed a neutralizing antibody titer of ≥20. Univariate analysis with neutralizing antibodies as a dependent variable and the degree of disease severity and underlying medical conditions as fixed factors revealed that patients with no previous history of non-communicable diseases and moderate clinical manifestation had the strongest neutralizing antibody response “Mean: 561.11”. Participants with severe symptoms and other underlying disorders, including deceased individuals, demonstrated the lowest neutralizing antibody response. Anti-spike protein antibody responses, as measured by ELISA, showed a statistically significant correlation with neutralizing antibodies. This reinforces the speculation that serological assays complement molecular testing for diagnostics; however, patients’ previous medical history (anamnesis) should be considered in interpreting serological results

Clinical and Serological Findings of COVID-19 Participants in the Region of Makkah, Saudi Arabia

Makkah in Saudi Arabia hosts the largest annual religious event in the world. Despite the many strict rules enacted, including Hajj cancellation, city lockdowns, and social distancing, the region has the second highest number of new COVID-19 cases in Saudi Arabia. Public health interventions that identify, isolate, and manage new cases could slow the infection rate. While RT-PCR is the current gold standard in SARS-CoV-2 identification, it yields false positive and negative results, which mandates the use of complementary serological tests. Here, we report the utility of serological assays during the acute phase of individuals with moderate and severe clinical manifestations of SARS-CoV-2 (COVID19). Fifty participants with positive RT-PCR results for SARS-CoV-2 were enrolled in this study. Following RT-PCR diagnosis, serum samples from the same participants were analyzed using in-house ELISA (IgM, IgA, and IgG) and microneutralization test (MNT) for the presence of antibodies. Of the 50 individuals analyzed, 43 (86%) showed a neutralizing antibody titer of ≥20. Univariate analysis with neutralizing antibodies as a dependent variable and the degree of disease severity and underlying medical conditions as fixed factors revealed that patients with no previous history of non-communicable diseases and moderate clinical manifestation had the strongest neutralizing antibody response “Mean: 561.11”. Participants with severe symptoms and other underlying disorders, including deceased individuals, demonstrated the lowest neutralizing antibody response. Anti-spike protein antibody responses, as measured by ELISA, showed a statistically significant correlation with neutralizing antibodies. This reinforces the speculation that serological assays complement molecular testing for diagnostics; however, patients’ previous medical history (anamnesis) should be considered in interpreting serological results. Keywords: SARS-CoV-2; ELISA; micro-neutralization assay; IgM; IgA; IgG ELISA; Makkah; Saudi Arabi

The impact of law enforcement on dispensing antibiotics without prescription: a multi-methods study from Saudi Arabia

Background: Dispensing of antibiotics without a prescription (DAwP) has been widely practised among community pharmacies in Saudi Arabia despite being illegal. However, in May 2018, the law and regulations were enforced alongside fines. Consequently, we wanted to evaluate the impact of these changes. Methods: A study was conducted among 116 community pharmacies in two phases. A pre-law enforcement phase between December 2017 and March 2018 and a post-law enforcement phase one year later. Each phase consisted of a cross-sectional questionnaire-based survey and a simulated client method (SCM) approach. In the SCM, clients presented with either pharyngitis or urinary tract infections (UTI). In SCM, for each phase, all 116 pharmacies were visited with one of the scenarios. Results: Before the law enforcement, 70.7% of community pharmacists reported that DAwP was common with 96.6% and 87.7% of participating pharmacies dispensed antibiotics without a prescription for pharyngitis and UTI respectively. After the law enforcement, only 12.9% reported that DAwP is still a common practice, with only 12.1% and 5.2% dispensing antibiotics without prescriptions for pharyngitis and UTI respectively. Conclusion: law enforcement was effective. However, there is still further scope for improvement. This could include further educational activities with pharmacists, physicians and the public