Bad bosses and despotism at workplace: A systematic review of the despotic leadership literature

Over the years, the concept of despotic leadership (DL) has emerged as a hot topic in academic and professional debates on leadership. To this end, this study aims to synthesize existing literature on despotic leadership in business management scholarship. We utilize a systematic literature review technique to systematically identify, select, and evaluate existing scholarly publications on despotic leadership to highlight emerging topics, theories, and the consequences of despotic leadership at the workplace. In addition, we also provide a set of specific research questions for advancements of DL in management and leadership research as well as to clarify its conceptual and operationalization ambiguities. The findings of this review are categorized as follows, i) theory and conceptualization of DL, ii) state-of-the-art research profiling, iii) key thematic areas, and iv) future agenda. The key implications of this review for theory and practice are discussed.

Recent Progress in Emerging Novel MXenes Based Materials and their Fascinating Sensing Applications

Early transition metals based 2D carbides, nitrides and carbonitrides nanomaterials are known as MXenes, a novel and extensive new class of 2D materials family. Since the first accidently synthesis based discovery of Ti₃ C₂ in 2011, more than 50 additional compositions have been experimentally reported, including at least eight distinct synthesis methods and also more than 100 stoichiometries are theoretically studied. Due to its distinctive surface chemistry, graphene like shape, metallic conductivity, high hydrophilicity, outstanding mechanical and thermal properties, redox capacity and affordable with mass-produced nature, this diverse MXenes are of tremendous scientific and technological significance. In this review, first we'll come across the MXene based nanomaterials possible synthesis methods, their advantages, limitations and future suggestions, new chemistry related to their selected properties and potential sensing applications, which will help us to explain why this family is growing very fast as compared to other 2D families. Secondly, problems that help to further improve commercialization of the MXene nanomaterials based sensors are examined, and many advances in the commercializing of the MXene nanomaterials based sensors are proposed. At the end, we'll go through the current challenges, limitations and future suggestions.

van der Waals integration of mixed-dimensional CeO2@Bi heterostructure for high-performance self-powered photodetector with fast response speed

Heterostructures have been extensively investigated for optoelectronic devices owing to their fantastic physicochemical properties. Herein, a mixed-dimensional van der Waals heterostructure (vdWH) CeO₂@Bi, 1D ceria (CeO₂) loaded with 0D bismuth quantum dots (Bi QDs), is synthesized through a facile hydrothermal bottom-up method. It is found that the fabricated CeO₂@Bi-based photoelectrochemical (PEC)-type photodetector (PD) shows self-powered photodetection capability with a fast photoresponse speed of 0.02 s. Besides, a photocurrent of 2.00 μA cm^-2 and a photoresponsivity of 888.89 μA W^-1 under 365 nm illumination are obtained. Furthermore, good long-term cycle stability is also observed after 1 month in a harsh environment, indicating the great potential for practical applications. These results are further supported by density functional theory (DFT) calculations. We believe that the presented work is expected to provide a new pathway for the future utilization of vdWHs for high-performance optoelectronics.

Infrared Light Emission Devices Based on Two-Dimensional Materials

Two-dimensional (2D) materials have garnered considerable attention due to their advantageous properties, including tunable bandgap, prominent carrier mobility, tunable response and absorption spectral band, and so forth. The above-mentioned properties ensure that 2D materials hold great promise for various high-performance infrared (IR) applications, such as night vision, remote sensing, surveillance, target acquisition, optical communication, etc. Thus, it is of great significance to acquire better insight into IR applications based on 2D materials. In this review, we summarize the recent progress of 2D materials in IR light emission device applications. First, we introduce the background and motivation of the review, then the 2D materials suitable for IR light emission are presented, followed by a comprehensive review of 2D-material-based spontaneous emission and laser applications. Finally, further development directions and challenges are summarized. We believe that milestone investigations of 2D-material-based IR light emission applications will emerge soon, which are beneficial for 2D-material-based nano-device commercialization.

Recent Advances in Oxidation Stable Chemistry of 2D MXenes

As an emerging star of 2D nanomaterials, 2D transition metal carbides and nitrides, named MXenes, present a large potential in various research areas owing to their intrinsic multilayer structure and intriguing physico-chemical properties. However, the fabrication and application of functional MXene-based devices still remain challenging as they are prone to oxidative degradation under ambient environment. Within this review, the preparation methods of MXenes focusing on the recent investigations on their thermal structure-stability relationships in inert, oxidizing, and aqueous environments are systematically introduced. Moreover, the key factors that affect the oxidation of MXenes, such as, atmosphere, temperature, composition, microstructure, and aqueous environment, are reviewed. Based on different scenarios, strategies for avoiding or delaying the oxidation of MXenes are proposed to encourage the utilization of MXenes in complicated environments, especially at high temperature. Furthermore, the chemistry of MXene-derived oxides is analyzed, which can offer perspectives on the further design and fabrication of novel 2D composites with the unique structures of MXenes being preserved.

Recent development in graphdiyne and its derivative materials for novel biomedical applications

Graphdiyne (GDY), which possess sp- and sp²-hybridized carbon and Dirac cones, offers unique physical and chemical properties, including an adjustable intrinsic bandgap, excellent charge carrier transfer efficiency, and superior conductivity compared to other carbon allotropes. These exceptional qualities of GDY and its derivatives have been successfully used in a variety of fields, including catalysis, energy, environmental protection, and biological applications. Herein, we focus on the potential application of GDY and its derivatives in the biomedical domain, including biosensing, biological protection, cancer therapy, and antibacterial agents, demonstrating how the biomimetic behavior of these materials can be a step forward in bridging the gap between nature and applications. Considering the excellent biocompatibility, solubility and selectivity of GDY and its derived materials, they have shown great potential as biosensing and bio-imaging materials. The unusual combination of properties in GDY has been used in biological applications such as "OFF-ON" DNA detection and enzymatic sensing, where GDY has a greater adsorption capacity than graphene and other 2D materials, resulting in increased sensitivity. GDY and its derivatives have also been used in cancer treatment due to their high doxorubicin (DOX) loading capacity (using-stacking) and photothermal conversion ability, and radiation protection since their initial biological use. The poor biodegradation rate of graphene demands the search for new nanomaterials. Accordingly, GDY has better biocompatibility and bio-safety than other 2D nanomaterials, especially graphene and its oxide, due to its absence of aggregation in the physiological environment. Thus, GDY-based nanomaterials have become promising candidates as bio-delivery carriers. Besides, GDY and GDY-based materials have also shown interesting applications in the fields of cell-culture, cell-growth and tissue engineering. Herein, we present a comprehensive review on the applications of GDY and its derivatives as biomedical materials, followed by their future perspectives. This review will provide an outlook for the application of graphene and its derivatives and may open up new horizons to inspire broader interests across various disciplines. Finally, the future prospects for GDY-based materials are examined for their potential biological use.

A novel MnO-CrN nanocomposite based non-enzymatic hydrogen peroxide sensor

A MnO–CrN composite was obtained via the ammonolysis of the low-cost nitride precursors Cr(NO₃)₃·9H₂O and Mn(NO₃)₂·4H₂O at 800 °C for 8 h using a sol–gel method. The specific surface area of the synthesized powder was measured via BET analysis and it was found to be 262 m² g⁻¹. Regarding its application, the electrochemical sensing performance toward hydrogen peroxide (H₂O₂) was studied via applying cyclic voltammetry (CV) and amperometry (i–t) analysis. The linear response range was 0.33–15 000 μM with a correlation coefficient (R²) value of 0.995. Excellent performance toward H₂O₂ was observed with a limit of detection of 0.059 μM, a limit of quantification of 0.199 μM, and sensitivity of 2156.25 μA mM⁻¹ cm⁻². A short response time of within 2 s was achieved. Hence, we develop and offer an efficient approach for synthesizing a new cost-efficient material for H₂O₂ sensing.

A MnO–CrN composite was obtained via the ammonolysis of the low-cost nitride precursors Cr(NO₃)₃·9H₂O and Mn(NO₃)₂·4H₂O at 800 °C for 8 h using a sol–gel method.

Evolution of low-dimensional material-based field-effect transistors

Field-effect transistors (FETs) have tremendous applications in the electronics industry due to their outstanding features such as small size, easy fabrication, compatibility with integrated electronics, high sensitivity, rapid detection and easy measuring procedures. However, to meet the increasing demand of the electronics industry, efficient FETs with controlled short channel effects, enhanced surface stability, reduced size, and superior performances based on low-dimensional materials are desirable. In this review, we present the developmental roadmap of FETs from conventional to miniaturized devices and highlight their prospective applications in the field of optoelectronic devices. Initially, a detailed study of the general importance of bulk and low-dimensional materials is presented. Then, recent advances in low-dimensional material heterostructures, classification of FETs, and the applications of low-dimensional materials in field-effect transistors and photodetectors are presented in detail. In addition, we also describe current issues in low-dimensional material-based FETs and propose potential approaches to address these issues, which are crucial for developing electronic and optoelectronic devices. This review will provide guidelines for low-dimensional material-based FETs with high performance and advanced applications in the future.

Broadband Nonlinear Photonics in Few-Layer Borophene

In this paper, 2D borophene is synthesized through a liquid-phase exfoliation. The morphology and structure of as-prepared borophene are systemically analyzed, and the Z-scan is used to measure the nonlinear optical properties. It is found that the saturable absorber (SA) properties of borophene make it serve as an excellent broadband optical switch, which is strongly used for mode-locking in near- and mid-infrared laser systems. Ultrastable pulses with durations as short as 792 and 693 fs are successfully delivered at the central wavelengths of 1063 and 1560 nm, respectively. Furthermore, stable pulses at a wavelength of 1878 nm are demonstrated from a thulium mode-locked fiber laser based on the same borophene SA. This research reveals a significant potential for borophene used in lasers helping extending the frontiers of photonic technologies.

Recent progress, challenges, and prospects in emerging group-VIA Xenes: synthesis, properties and novel applications

The discovery of graphene (G) attracted considerable attention to the study of other novel two-dimensional materials (2DMs), which is identified as modern day "alchemy" since researchers are converting the majority of promising periodic table elements into 2DMs. Among the family of 2DMs, the newly invented monoelemental, atomically thin 2DMs of groups IIIA-VIA, called "Xenes" (where, X = IIIA-VIA group elements, and "ene" is the Latin word for nanosheets (NSs)), are a very active area of research for the fabrication of future nanodevices with high speed, low cost and elevated efficiency. Currently, any novel structure of 2DMs from the typical Xenes will probably be applicable in electronic technology. Analysis of their possible highly sensitive synthesis and characterization present opportunities for theoretically examining proposed 2D-Xenes with atomic precision in ideal circumstances, thus providing theoretical predictions for experimental support. Several theoretically predicted and experimentally synthesized 2D-Xene materials have been investigated for the group-VIA elements (tellurene (2D-Te), and selenene (2D-Se)), which are similar to topological insulators (TIs), thus potentially rendering them suitable materials for application in upcoming nanodevices. Although the investigation and device application of these materials are still in their infancy, theoretical studies and a few experiment-based investigations have proven that they are complementary to conventional (i.e., layered bulk-derived) 2DMs. This review focuses on the synthesis of novel group-VIA Xenes (2D-Te and 2D-Se) and summarizes the current development in understanding their basic properties, with the current advancement in signifying device applications. Lastly, the future research prospects, further advanced applications and associated shortcomings of the group-VIA Xenes are summarized and highlighted.

Recent Progress, Challenges, and Prospects in Two-Dimensional Photo-Catalyst Materials and Environmental Remediation

The successful photo-catalyst library gives significant information on feature that affects photo-catalytic performance and proposes new materials. Competency is considerably significant to form multi-functional photo-catalysts with flexible characteristics. Since recently, two-dimensional materials (2DMs) gained much attention from researchers, due to their unique thickness-dependent uses, mainly for photo-catalytic, outstanding chemical and physical properties. Photo-catalytic water splitting and hydrogen (H2) evolution by plentiful compounds as electron (e-) donors is estimated to participate in constructing clean method for solar H2-formation. Heterogeneous photo-catalysis received much research attention caused by their applications to tackle numerous energy and environmental issues. This broad review explains progress regarding 2DMs, significance in structure, and catalytic results. We will discuss in detail current progresses of approaches for adjusting 2DMs-based photo-catalysts to assess their photo-activity including doping, hetero-structure scheme, and functional formation assembly. Suggested plans, e.g., doping and sensitization of semiconducting 2DMs, increasing electrical conductance, improving catalytic active sites, strengthening interface coupling in semiconductors (SCs) 2DMs, forming nano-structures, building multi-junction nano-composites, increasing photo-stability of SCs, and using combined results of adapted approaches, are summed up. Hence, to further improve 2DMs photo-catalyst properties, hetero-structure design-based 2DMs' photo-catalyst basic mechanism is also reviewed.

Two-Dimensional Tellurium: Progress, Challenges, and Prospects

Since the successful fabrication of two-dimensional (2D) tellurium (Te) in 2017, its fascinating properties including a thickness dependence bandgap, environmental stability, piezoelectric effect, high carrier mobility, and photoresponse among others show great potential for various applications. These include photodetectors, field-effect transistors, piezoelectric devices, modulators, and energy harvesting devices. However, as a new member of the 2D material family, much less known is about 2D Te compared to other 2D materials. Motivated by this lack of knowledge, we review the recent progress of research into 2D Te nanoflakes. Firstly, we introduce the background and motivation of this review. Then, the crystal structures and synthesis methods are presented, followed by an introduction to their physical properties and applications. Finally, the challenges and further development directions are summarized. We believe that milestone investigations of 2D Te nanoflakes will emerge soon, which will bring about great industrial revelations in 2D materials-based nanodevice commercialization.

Facile Synthesis of Mayenite Electride Nanoparticles Encapsulated in Graphitic Shells Like Carbon Nano Onions: Non-noble-metal Electrocatalysts for Oxygen Reduction Reaction (ORR)

This manuscript presented a large scale synthesis of Graphitic Shells like carbon nano onions (GS-CNOs) by direct solution method using mayenite electride as a catalyst for synthesis of CNOs. Thermal characterization, microstructural analysis, and high resolution electron microscopy have confirmed the graphitization and revealed the resulting GS-CNOs with particle size about 15 nm, maximum BET surface area of 214 m2.g-1, and moderate conductivity of 250 S.cm-1, thus providing a new approach to synthesize GS-CNOs. The reported GS-CNOs, which acts as more active but less expensive electrocatalysts with onset potential of 1.03 V, half wave potential of 0.88 V vs. the reversible hydrogen electrode (RHE), and limited current density of 5.9 mA.cm-2, higher than that of benchmark 20% Pt/C (1.02 eV, 0.82 V, 5.2 mA.cm-2). The synthesized nano-powder acts as an origin of ORR activity via a four electron (4e-) pathway, along with significantly enhanced stability, in alkaline media. The high ORR activity is ascribed to GS-CNOs embedded sufficient metallic C12A7:e- particles, which favor faster electron movement and better adsorption of oxygen molecules on catalyst surface. Hence, we explored first time large scale synthesis of GS-CNOs with gram level and provide efficient approach to prepare novel, lowest cost, potential non-noble metals catalyst for fuel cells.

Fe-doped mayenite electride composite with 2D reduced Graphene Oxide: As a non-platinum based, highly durable electrocatalyst for Oxygen Reduction Reaction

Since the last decades, non-precious metal catalysts (NPMC), especially iron based electrocatalysts show sufficient activity, potentially applicant in oxygen reduction reaction (ORR), however they only withstand considerable current densities at low operating potentials. On the other hand iron based electrocatalysts are not stable at elevated cathode potentials, which is essential for high energy competence, and its remains difficult to deal. Therefore, via this research a simple approach is demonstrated that allows synthesis of nanosize Fe-doped mayenite electride, [Ca24Al28O64]4+·(e-)4 (can also write as, C12A7-xFex:e-, where doping level, x = 1) (thereafter, Fe-doped C12A7:e-), consist of abundantly available elements with gram level powder material production, based on simple citrate sol-gel method. The maximum achieved conductivity of this first time synthesized Fe-doped C12A7:e- composite materials was 249 S/cm. Consequently, Fe-doped C12A7:e- composite is cost-effective, more active and highly durable precious-metal free electrocatalyst, with 1.03 V onset potential, 0.89 V (RHE) half-wave potential, and ~5.9 mA/cm2 current density, which is higher than benchmark 20% Pt/C (5.65 mA/cm2, and 0.84 V). The Fe-doped C12A7:e- has also higher selectivity for desired 4e- pathway, and more stable than 20 wt% Pt/C electrode with higher immunity towards methanol poisoning. Fe-doped C12A7:e- loses was almost zero of its original activity after passing 11 h compared to the absence of methanol case, indicates that to introduce methanol has almost negligible consequence for ORR performance, which makes it highly desirable, precious-metal free electrocatalyst in ORR. This is primarily described due to coexistence of Fe-doped C12A7:e- related active sites with reduced graphene oxide (rGO) with pyridinic-nitrogen, and their strong coupling consequence along their porous morphology textures. These textures assist rapid diffusion of molecules to catalyst active sites quickly. In real system maximum power densities reached to 243 and 275 mW/cm2 for Pt/C and Fe-doped C12A7:e- composite, respectively.

Recent advances in two-dimensional materials and their nanocomposites in sustainable energy conversion applications

Two-dimensional (2D) materials have a wide platform in research and expanding nano- and atomic-level applications. This study is motivated by the well-established 2D catalysts, which demonstrate high efficiency, selectivity and sustainability exceeding that of classical noble metal catalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and/or hydrogen evolution reaction (HER). Nowadays, the hydrogen evolution reaction (HER) in water electrolysis is crucial for the cost-efficient production of a pure hydrogen fuel. We will also discuss another important point related to electrochemical carbon dioxide and nitrogen reduction (ECR and N2RR) in detail. In this review, we mainly focused on the recent progress in the fuel cell technology based on 2D materials, including graphene, transition metal dichalcogenides, black phosphorus, MXenes, metal-organic frameworks, and metal oxide nanosheets. First, the basic attributes of the 2D materials were described, and their fuel cell mechanisms were also summarized. Finally, some effective methods for enhancing the performance of the fuel cells based on 2D materials were also discussed, and the opportunities and challenges of 2D material-based fuel cells at the commercial level were also provided. This review can provide new avenues for 2D materials with properties suitable for fuel cell technology development and related fields.

Novel Two-Dimensional Carbon-Chromium Nitride-Based Composite as an Electrocatalyst for Oxygen Reduction Reaction

For future pollution-free renewable energy production, platinum group metal (PGM)-free electrocatalysts are highly required for oxygen reduction reaction (ORR) to avoid all possible Fenton reactions and to make fuel cell more economical. Therefore, in this study, to overcome traditional electrocatalyst limitations, we applied facile method to synthesize robust mesoporous CrN-reduced graphene oxide (rGO) nanocomposite with MnO (thereafter, Cr/rGO composite with MnO) as an electrocatalyst by efficient one-step sol-gel method by ammonolysis at 900°C for 9 h. Synthesized porous structures of Cr/rGO nanocomposite with MnO have the highest estimated surface area of 379 m2·g-1, higher than that of the carbon black (216 m2·g cat - 1 ) support, and almost uniform pore size distribution of about 4 nm. The Cr/rGO nanocomposites with MnO exhibit enhanced electrocatalytic ORR properties with estimated high half-wave potential of 0.89 V vs. the reversible hydrogen electrode (RHE) and current density of 5.90 mA·cm-2, compared with that of benchmark 20% Pt/C electrode (0.84 V, 5.50 mA·cm-2), with noticeable methanol tolerance and significantly enhanced stability in alkaline media. Hence, the Cr/rGO nanocomposites with MnO showed superior performance to 20 wt.% Pt/C; their half-wave potentials were 50 mV high, and the limiting current density was 0.40 mA·cm-2 high. In alkaline anion exchange membrane fuel cell (AAEMFC) setup, this cell delivers a power density of 309 mW·cm-2 for Cr/rGO nanocomposite with MnO, demonstrating its potential use for energy conversion applications. The nanosized Cr/rGO metallic crystalline nanocomposites with MnO gave a large active surface area owing to the presence of rGO, which also has an effect on the charge distribution and electronic states. Hence, it may be the reason that Cr/rGO nanocomposites with MnO, acting as more active and more stable catalytic materials, boosted the electrocatalytic properties. The synergistic consequence in nanosized Cr/rGO composite with MnO imparts the materials' high electron mobility and thus robust ORR activity in 0.1 M of KOH solution. This potential method is highly efficient for synthesis of large-scale, non-noble-metal-based electrocatalytic (NNME) materials (i.e., Cr/rGO nanocomposite with MnO) on the gram level and is efficient in preparing novel, low-cost, and more stable non-PGM catalysts for fuel cells.

Nickel-Based Transition Metal Nitride Electrocatalysts for the Oxygen Evolution Reaction

Electrocatalysis is an efficient and promising means of energy conversion, with minimal environmental footprint. To enhance reaction rates, catalysts are required to minimize overpotential. Alternatives to noble metal electrocatalysts are essential to address these needs on a large scale. In this context, transition metal nitride (TMN) nanoparticles have attracted much attention owing to their high catalytic activity, distinctive electronic structures, and enhanced surface morphologies. Nickel-based materials are an ideal choice for electrocatalysts given nickel's abundance and low cost in comparison to noble metals. In this Minireview, advancements made specifically in Ni-based binary and ternary TMNs as electrocatalysts for the oxygen evolution reaction (OER) are critically evaluated. When used as OER electrocatalysts, Ni-based nanomaterials with 3 D architectures on a suitable support (e.g., a foam support) speed up electron transfer as a result of well-oriented crystal structures and also assist intermediate diffusion, during reaction, of evolved gases. 2 D Ni-based nitride sheet materials synthesized without supports usually perform better than 3 D supported electrocatalysts. The focus of this Minireview is a systematic description of OER activity for state-of-the-art Ni-based nitrides as nanostructured electrocatalysts.

Single step synthesis of highly conductive room-temperature stable cation-substituted mayenite electride target and thin film

Novel approaches to synthesize efficient inorganic electride [Ca24Al28O64]4+(e-)4 (thereafter, C12A7:e-) at ambient pressure under nitrogen atmosphere, are actively sought out to reduce the cost of massive formation of nanosized powder as well as compact large size target production. It led to a new era in low cost industrial applications of this abundant material as Transparent Conducting Oxides (TCOs) and as a catalyst. Therefore, the present study about C12A7:e- electride is directed towards challenges of cation doping in C12A7:e- to enhance the conductivity and form target to deposit thin film. Our investigation for cation doping on structural and electrical properties of Sn- and Si-doped C12A7:e- (Si-C12A7:e, and Sn-C12A7:e-) reduced graphene oxide (rGO) composite shows the maximum achieved conductivities of 5.79 S·cm-1 and 1.75 S·cm-1 respectively. On the other hand when both samples melted, then rGO free Sn-C12A7:e- and Si-C12A7:e- were obtained, with conductivities ~280 S.cm-1 and 300 S·cm-1, respectively. Iodometry based measured electron concentration of rGO free Sn-C12A7:e- and Si-C12A7:e-, 3 inch electride targets were ~2.22 × 1021 cm-3, with relative 97 ± 0.5% density, and ~2.23 × 1021 cm-3 with relative 99 ± 0.5% density, respectively. Theoretical conductivity was already reported excluding any associated experimental support. Hence the above results manifested feasibility of this sol-gel method for different elements doping to further boost up the electrical properties.

Facile synthesis of tin-doped mayenite electride composite as a non-noble metal durable electrocatalyst for oxygen reduction reaction (ORR)

In this study, we synthesized nanosized Sn-doped C12A7:e- (C12Al7-xSnx:e-, where x = 0.20 to 1) composite with high surface area of 244 m2 g-1. An increasing trend in conductivity of Sn-doped C12A7:e- composites was observed at 300 K: 24 S cm-1, 68 S cm-1, 190 S cm-1 and 290 S cm-1, at doping levels of x = 0.20, 0.40, 0.80, and 1, respectively. Sn-doped C12A7:e-, with and without reduced graphene oxide (rGO), acts as a less expensive and highly active and durable electrocatalyst in the oxygen reduction reaction (ORR) for fuel cells. In the case of C12A7-xSnx:e- (where x = 1), calculated onset potential and current density were comparable to the commercially available 20% Pt/C electrode. Moreover, significant improvement was observed for Sn-doped C12A7:e- (doping level x = 1) with rGO composite. The ORR current density was about 5.9 mA cm-2, which was higher than that of Pt/C (5.2 mA cm-2). Our investigation of the effect of cation doping on structural and electrical properties of Sn-doped C12A7:e- composites shows that these results manifested the feasibility of this sol-gel method for different element doping. Furthermore, the as-prepared promising non-noble metal catalysts (NNMCs), viz., Sn-doped C12A7:e- composite materials, possess intrinsic long-time stability and excellent methanol resistance toward ORR in alkaline media and may serve as a promising alternative to Pt/C materials for ORR in its widespread implementation in fuel cells.

Facile synthesis of a cationic-doped [Ca24Al28O64]4+(4e-) composite via a rapid citrate sol-gel method

One of the greatest challenges in the enhancement of the electrical properties of conductive mayenite [Ca₂₄Al₂₈O₆₄]⁴⁺(4e^-) (hereinafter C12A7:e^-) is the design of a more suitable/simple synthesis strategy that can be employed to obtain the required properties such as excellent stable electrical conductivity, a high electron concentration, outstanding mobility, and an exceptionally large surface area. Therefore, to synthesize C12A7:e^- in the metallic state, we proposed a facile, direct synthesis strategy based on an optimized sol-gel combustion method under a nitrogen gas environment using the low-cost precursors Ca(NO₃)₂·4H₂O and Al(NO₃)₃·9H₂O. Using this developed strategy, we successfully synthesized moderately conductive nanoscale C12A7:e^- powder, but with unexpected carbon components (reduced graphene oxide (rGO) and/or graphene oxide (GO)). The synthesized C12A7:e^- composite at room temperature has an electrical conductivity of about 21 S cm^-1, a high electron concentration of approximately 1.5 × 10²¹ cm^-3, and a maximum specific surface area of 265 m² g^-1. Probably, the synthesized rGO was coated on nanocage C12A7:e^- particles. In general, the C12A7:e^- electride is sensitive to the environment (especially to oxygen and moisture) and protected by an rGO coating on C12A7:e^- particles, which also enhances the mobility and keeps the conductivity of C12A7:e^- electride stable over a long period. Doped mayenite electride exhibits a conductivity that is strongly dependent on the substitution level. The conductivity of gallium-doped mayenite electride increases with the doping level and has a maximum value of 270 S cm^-1, which for the first time has been reported for the stable C12A7:e^- electride. In the case of Si-substituted calcium aluminate, the conductivity has a maximum value of 222 S cm^-1 at room temperature.

Facile metal-free reduction-based synthesis of pristine and cation-doped conductive mayenite

A facile method to prepare pristine nanoscale mayenite electride is presented. The highest achieved conductivity of melted sample was ~28 S cm⁻¹, with 93% mass density.

Efficacy of CVD Risk Factor Modification in a Lower-Middle Class Community in Pakistan: The Metroville Health Study

The Metroville Health Study aimed to reduce consumption of total cooking fats by 33%, salt by 25% and replace ghee with vegetable oil in a lower middle class urban community in Pakistan. Households (n=403) were randomly assigned to Intervention and Control groups. A baseline screening collected data on CVD risk factors, knowledge and attitudes and household consumption of cooking fats and salt. Intervention households received information about CVD and regular visits by social workers who measured cooking fats and salt and counselled cooks on the goals of intervention. Two years later, 291 households were re-screened. Intervention households reduced consumption of fats and salt compared to differences were total fat, 48% ( p<0.0001); ghee, 37% ( p=0.005); vegetable oil, 33% ( p=0.0001); and salt, 41% ( p=0.011). Household visits by trained social workers were effective in achieving reductions in consumption of cooking fat and salt in a lower class urban community. Asia Pac J Public Health 2003; 15(1): 30-36.

Evaluation of paromomycin sulphate topical ointment as effective therapeutic agent in cutaneous leishmaniasis

This is a prospective open study of randomly selected 35 patients with a single sore of cutaneous leishmaniasis who were treated with paromomycin sulphate topical ointment for 4 weeks. According to the observations made on days 0, 15, 45 and 105 after the careful application twice a day in 2 lengths from one side of the lesion to the other at right angles to each other and then smeared to cover the whole surface of the sore, the overall efficacy of the ointment as therapeutic agent was 91%. There was a mild and temporary adverse reaction in the form of painless, non-itching nodulation around the ulcers in 10 (28%) patients after 15 days application which disappeared within 5-7 days of further application. It thus proved a promising, simple and inexpensive remedial agent without any undesirable side effects as compared to other complicated and unpredictable therapeutic regimens.

Thyroid hormone in hyperemesis gravidarum

OBJECTIVE

Several studies have suggested that nausea and vomiting in early pregnancy are related to the levels of thyroid hormones and human chorionic gonadotropin (hCG). To ascertain this relationship, we investigated 60 pregnant women (30 subjects each with morning sickness and hyperemesis gravidarum) and compared them with 30 control subjects (by enzyme immunoassay method).

METHODS

Serum T3, T4 and TSH were determined in all the subjects while serum hCG was assayed in pregnant women only. Group comparison was done by applying Student's t-test and the relationship between various parameters was evaluated by calculating coefficient of correlation, "r".

RESULTS

Serum T4 and hCG levels were significantly increased in hyperemesis gravidarum while TSH demonstrated a significant decline in the same group. Correlation analysis showed a direct relationship between serum T4 and hCG and an inverse relationship between serum TSH and hCG in pregnancy with morning sickness.

CONCLUSION

Our results are suggestive of the involvement of these variables in the pathogenesis of morning sickness and hyperemesis gravidarum not only because their levels were significantly altered but the extent of increase or decrease in their level correlated well with the severity of symptoms in the study subjects.

Methicillin resistant staphylococcus aureus in a teaching hospital of Karachi--a laboratory study

A search was made for Methicillin Resistant Strains of Staphylococcus Aureus (MRSA) among staph aureus cultures isolated at a teaching hospital in Karachi. Of 100 staphylococcus aureus isolated in 1987-88, 5 were MRSA, four from admitted patients and one from outpatient. These MRSA were resistant to Gentamicin as well as to other antibiotics. The presence of MRSA in the in-patients is a serious problem as it can act as reservoir to cause outbreak of colonisation and infection. No MRSA was isolated from 50 samples studied from Quetta.