Corporate social responsibility and firm performance nexus: Moderating role of CEO chair duality.

This study aims to explore the link between corporate social responsibility (CSR) and firm performance in the presence of the moderating role of CEO chair duality. It is widely believed that CSR initiatives and firm performance are largely influenced by psychological factors and the behavior of the decision maker (manager/CEO). Hence, CEO chair duality may play an instrumental role in shaping CSR initiatives to enhance firm performance. For empirical investigation, the study used the dynamic panel data method with generalized method of moment (GMM) parameters. The study considered 131 firms listed on the Pakistan Stock Exchange (PSX), yielding 1508 firm-year observations, over the period 2006 to 2020. Our results reveal that the impact of CSR on book-based and market-based measures differs due to the asymmetry of information in the market. The market discounts CEO chair duality due to the concentration of power and translates it into negative impact of CSR on firm performance. Thus, firms should not only improve CSR activities but also take steps to reduce asymmetry in markets because the impact on book-based measures and market-based measures of performance are not consistent. Society should also play a role to convince firms in a better way to take CSR initiatives. The perception of transparency should also be improved as CEO chair duality is being negatively seen by the market.

Predictive effect of investor sentiment on current and future returns in emerging equity markets.

This study uses Non-linear Predictive Regression Analysis to analyze the effect of investor sentiment on the returns of the selected developing equity markets, including Brazil, South Africa, Indonesia, India, China, Russia, and Pakistan. The Principal Component Analysis is applied to construct an Investor Sentiment Index. In most selected countries, investor sentiment substantially affects contemporaneous market returns, and this effect remains persistent in the short term. However, it becomes less prominent over time. It suggests that stakeholders should give importance to the investors' sentiments while making investment decisions.

Association between maternal chronic apical periodontitis (CAP) and low birth weight preterm birth (LBWPT).

OBJECTIVE: To determine the association between maternal chronic apical periodontitis and low birth weight preterm birth. METHODS: The case-control study was conducted at the Gynaecology Ward of the Civil Hospital, Karachi, from September 2017 to April 2018, and comprised women aged 19-48 years with singleton pregnancy delivering spontaneously. The subjects were examined for the presence of periodontitis. The mothers who delivered low birth weight preterm babies were the cases in group A and those who delivered normal birth weight babies were the controls in group B. On the delivery day, after the subject having been moved to the room, data was collected through a questionnaire to record demographic details, history of pregnancy and information about the newborn. The radiographs were assessed for the presence of chronic apical periodontitis. The association between maternal chronic apical periodontitis and low birth weight preterm birth was subsequently determined. Data was analysed using SPSS 24. RESULTS: Of the 200 subjects, 100(50%) were in group A with a mean age of 27.17±5.11 years, and 100(50%) were in group B with a mean age of 27.08±4.90 years. Low birth weight preterm birth was associated with education level and family size (p<0.05). There was no association between maternal chronic apical periodontitis and low birth weight preterm birth (p>0.05). CONCLUSIONS: There was no association between maternal chronic apical periodontitis and low birth weight preterm birth.

Humidity sensor based on Gallium Nitride for real time monitoring applications.

Gallium Nitride (GaN) remarkably shows high electron mobility, wide energy band gap, biocompatibility, and chemical stability. Wurtzite structure makes topmost Gallium atoms electropositive, hence high ligand binding ability especially to anions, making it usable as humidity sensor due to water self-ionization phenomenon. In this work, thin-film GaN based humidity sensor is fabricated through pulse modulated DC magnetron sputtering. Interdigitated electrodes (IDEs) with 100 µm width and spacing were inkjet printed on top of GaN sensing layer to further enhance sensor sensitivity. Impedance, capacitance, and current response were recorded for humidity and bio-sensing applications. The sensor shows approximate linear impedance response between 0 and 100% humidity range, the sensitivity of 8.53 nF/RH% and 79 kΩ/RH% for capacitance and impedance, and fast response (Tres) and recovery (Trec) time of 3.5 s and 9 s, respectively. The sensor shows little hysteresis of < 3.53% with stable and wide variations for accurate measurements. Especially, it demonstrates temperature invariance for thermal stability. Experimental results demonstrate fabricated sensor effectively evaluates plant transpiration cycle through water level monitoring by direct attachment onto leaves without causing any damage as well as freshness level of meat loaf. These properties of the proposed sensor make it a suitable candidate for future electronics providing a low-cost platform for real time monitoring applications.

Printable Highly Stable and Superfast Humidity Sensor Based on Two Dimensional Molybdenum Diselenide.

Transition metal dichalcogenides (TMDCs) are promising materials for sensing applications, due to their exceptional high performance in nano-electronics. Inherentely, the chemical and thermal responses of TMDCs are highly stable, hence, they pave way for real time sensor applications. This article proposes inceptively a stable and superfast humidity sensor using two-dimensional (2D) Molybdenum diselenide (MoSe2) through printed technlogies. The 2D MoSe2 ink is synthesized through wet grinding to achieve few-layered nano-flakes. Inter digital electrodes (IDEs) are fabricated via screen-printing on Polyethylene terephthalate (PET) substrate and thin film of MoSe2 nano-flakes is fabricated through spin coating. The impedance and capacitance response are recorded at 1 kHz between temperature levels ranging from 20-30 °C. The impedance and capacitance hysteresis results are recorded <1.98% and <2.36%, respectively, ensuring very good repeatability during humidification and dehumidification. The stability of impedance and capacitance response are recorded with maximum error rate of ~ 0.162% and ~ 0.183%, respectively. The proposed sensor shows fast impedance response time (Tres) of ~ 0.96 s, and recovery time (Trec) of ~ 1.03 s, which has Tres of ~ 1.87 s, and Trec of ~ 2.13 s for capacitance. It is aimed to develop a high performance and stable humidity sensor for various monitoring applications.

Disposable all-printed electronic biosensor for instantaneous detection and classification of pathogens.

A novel disposable all-printed electronic biosensor is proposed for a fast detection and classification of bacteria. This biosensor is applied to classify three types of popular pathogens: Salmonella typhimurium, and the Escherichia coli strains JM109 and DH5-α. The proposed sensor consists of inter-digital silver electrodes fabricated through an inkjet material printer and silver nanowires uniformly decorated on the electrodes through the electrohydrodynamic technique on a polyamide based polyethylene terephthalate substrate. The best sensitivity of the proposed sensor is achieved at 200 µm teeth spaces of the inter-digital electrodes along the density of the silver nanowires at 30 × 103/mm2. The biosensor operates on ±2.5 V and gives the impedance value against each bacteria type in 8 min after sample injection. The sample data are measured through an impedance analyzer and analyzed through pattern recognition methods such as linear discriminate analysis, maximum likelihood, and back propagation artificial neural network to classify each type of bacteria. A perfect classification and cross-validation is achieved by using the unique fingerprints extracted from the proposed biosensor through all the applied classifiers. The overall experimental results demonstrate that the proposed disposable all-printed biosensor is applicable for the rapid detection and classification of pathogens.

Microstrip Patch Sensor for Salinity Determination.

In this paper, a compact microstrip feed inset patch sensor is proposed for measuring the salinities in seawater. The working principle of the proposed sensor depends on the fact that different salinities in liquid have different relative permittivities and cause different resonance frequencies. The proposed sensor can obtain better sensitivity to salinity changes than common sensors using conductivity change, since the relative permittivity change to salinity is 2.5 times more sensitive than the conductivity change. The patch and ground plane of the proposed sensor are fabricated by conductive copper spray coating on the masks made by 3D printer. The fabricated patch and the ground plane are bonded to a commercial silicon substrate and then attached to 5 mm-high chamber made by 3D printer so that it contains only 1 mL seawater. For easy fabrication and testing, the maximum resonance frequency was selected under 3 GHz and to cover salinities in real seawater, it was assumed that the salinity changes from 20 to 35 ppt. The sensor was designed by the finite element method-based ANSYS high-frequency structure simulator (HFSS), and it can detect the salinity with 0.01 ppt resolution. The designed sensor has a resonance frequency separation of 37.9 kHz and reflection coefficients under -20 dB at the resonant frequencies. The fabricated sensor showed better performance with average frequency separation of 48 kHz and maximum reflection coefficient of -35 dB. By comparing with the existing sensors, the proposed compact and low-cost sensor showed a better detection capability. Therefore, the proposed patch sensor can be utilized in radio frequency (RF) tunable sensors for salinity determination.

A flat-panel-shaped hybrid piezo/triboelectric nanogenerator for ambient energy harvesting.

Recently, many researchers have been paying attention to nanogenerators (NGs) as energy sources for self-powered mirco-nano systems, and studying how to achieve their higher power generation. Hence, we propose a hybrid-type NG for harvesting both the piezoelectric and triboelectric effect simultaneously. In the proposed hybrid NG, the piezoelectric NG (PNG) and triboelectric NG (TENG) are fabricated using polydimethylsiloxane (PDMS) and perovskite zinc stannite (ZnSnO3) nanocubes with a high charge polarization of 59 uC cm-2 composite (PDMS + ZnSnO3) and UV surface-treated PDMS, respectively. To effectively combine a high output current of PNG and a high voltage of TENG, these two NGs are stacked upon each other, and separated by sponge spacers providing a uniform air gap for the triboelectric effect. In particular, this fabricated structure has a low Young's modulus for piezoelectricity. The proposed hybrid NG device effectively achieves a combined peak voltage of 300 V on an open circuit, a power density of 10.41 mW cm-2 at 1 MΩ load, and a maximum short circuit current density of 16 mA cm-2 at 50 Ω load. It is feasible that the proposed NG can be utilized as a source for various self-powered systems.

All-Printed Differential Temperature Sensor for the Compensation of Bending Effects.

Because printed resistance temperature detectors (RTDs) are affected by tension and compression of metallic patterns on flexible or curved surfaces, a significant temperature-sensing error occurs in general. Hence, we propose a differential temperature sensor (DTS) to compensate the bending effect of the printed RTDs, which is composed of two serially connected similar meander patterns fabricated back-to-back on a polyimide polyethylene terephthalate substrate through a Dimatix DMP-3000 inkjet printer using silver nanoparticles. Under mechanical deformation, the resistance of the proposed DTS is not varied significantly under the same temperature environment because its patterns vary differentially as one side experiences tension while the opposite side experiences compression. A single meander pattern of the proposed DTS has a total length of 75 mm and device dimensions of 7 × 7 mm2. The total resistance variation is observed to be 15.5 Ω against the temperature variation from 0 to 100 °C, and the temperature coefficient of resistance is 1.076 × 10-3 °C-1. The proposed DTS exhibits no significant resistance change on bendability testing down to 2 mm diameter because of mechanical deformation. In addition, it is also used to detect the curvature of a body shape down to 2 mm diameter because its resistance changes by ±8.22% using a single meander pattern of DTS. The proposed sensor can be applied on a curved or flexible surface to measure relatively accurate temperature when compared to a single meander pattern.