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This paper seeks to study the effect of oil price volatility on economic growth in Middle East countries (Jordan, United Arab Emirates, Saudi Arabia, Kuwait, Qatar, and Turkey). The study's goals were achieved by utilising a range of econometric methodologies. For instance, the IPS and LLC procedures are used to study unit root qualities, while Westerlund and Edgerton's (2008) test is used to study cointegration. The findings demonstrate a long-term correlation between Oil price volatility, inflation, investment, and economic growth. The study concludes with more detailed findings regarding how oil prices affect gross domestic product growth. As such, policymakers can use it to support their decision-making.

In this research, the focus was on examining thin films of vanadium oxide (abbreviated as V2O5) with different levels of doping using nickel oxide (NiO) (X = 0, 6, 8)%. The films were created through pulsed laser deposition (PLD) method. The thin films were made and subjected to annealing at 450°C for a duration of one hour. The structural properties of the films were examined using the XRD diffraction technique, whereby the films' composition was found to be polycrystalline, featuring an orthorhombic structure. Notably, the films displayed a prominent alignment along the (111) plane, manifesting at an angle measuring approximately 27.889˚. The FE-SEM technology was utilized to explore and evaluate the surface morphology of the thin films. This showed a nanotube-to-spherical shape transformation. Following the implementation of EDX x-ray technique, it was determined that the films comprised the elemental components of vanadium (V), nickel (Ni), and oxygen (O), consistent with the doping ratios. The assessment of the films' optical properties was carried out through the utilization of UV–visible spectrophotometer, demonstrating decreased absorbance and absorption coefficient, as well as an increased energy gap from 2.32 eV to 2.93 eV. The electrical conductivity results indicated a decrease in direct current conductivity (σd.c) with increasing doping ratio, while the activation energy (Ea) increased. Consequently, these films can be utilized in thermoelectric generators.

This paper examines the financial factors affecting profitability across the listed Jordanian service companies. Insufficient attention has been paid to the influence of profitability specifically revealed by financial indicators. This study adopts the firm effect model. The investigation is established on panel data from 2015 to 2020, based on annual company reports. Regression was used to test the study hypotheses. The research sample is collected from the 46 public service firms listed. The profitability of Jordan’s service firms is measured by three proxies, including, Return on Equity (ROE), Earnings Per Share (EPS) and Return on Assets (ROA). The results reveal that firm size and liquidity positively and significantly impact profitability. Conversely, the findings verify that company efficiency and market power have no significant impact on profitability. Moreover, among Jordan’s service firms’ financial indicators, the findings confirm that neither firm nor sales growth have a significant influence on profitability, while sustainable growth rate has a positive, significant effect on profitability. The firm effects are higher for ROE than ROA and EPS. The study provides beneficial insights for managers and investors by providing effective policies designed to improve profitability. The results also provide shareholders with statistics that will ensure the profitability of companies operating in developing countries, such as Jordan.

In this review, the main approaches were utilized for fabrication nanostructure materials namely arc discharge, laser ablation, chemical vapor deposition, and green synthesis. Also, the advantages and disadvantages for each approach are discussed intensively. In addition, the structure and morphology of Carbon Nanotubes (CNTs), according to the number of layers CNTs classified single-wall carbon tubes (SWCTs), double wall carbon tubes (DWCTs), and multi-wall carbon tubes (MWCTs) are demonstrated in detail. SWCTs can be divided into chiral (m≠n), zigzag (m=0), and armchair (m=n) based on the geometrical arrangement of atoms or molecules. Moreover, some of the mechanical features of CNTs such as Young’s modules, strength and tensile strength, compressibility and deformability and fracture performance will be described. Throughout this review, it can be concluded that CNTs possess better mechanical features comparing with the analogous bulk or micro-scale tubes. For instance, Young’s module of CNTs increases by decreasing radius of CNTs. Furthermore, the strength and tensile strength of CNTs becomes stronger due to this covalent bond between carbon-carbon. On the other hand, compressibility and deformability will also improve due to the anisotropic feature of CNTs shape. It can be concluded that, CNTs possess a wide range of possible uses, and they can be used in nanoscale devices, electronic applications, optical operation, materials science, architecture and many more. Also, CNTs have been utilized in numerous novel applications owing to their unusual electrical features, unique strength, and heat transfer performance.

The study quantified the effect of gibberellic acid (GA3) as a pre-flowering treatment for male parent Giza 178 R and the influence of male to female ratio (2R:10A, 2R:12A, 2R:14A and 2R:16A) between male (R) to female (A) for two Cytoplasmic Male Sterility (CMS) lines (‘IR69625’ and ‘G46’) on hybrid rice seed production. The main plots were occupied by CMS lines while; GA3 application for male parent Giza 178R were arranged in the sub plots and male to female ratio was arranged in the sub-sub plots. The results indicated that, the, duration of floret opening, angle of floret opening, filaments exsertion, filaments length, anther length, plant height and number of tiller hill-1 of male parent Giza 178R were significantly at 300 g GA3 ha-1 concentration. Plant height, panicle exsertion, panicle length, flag leaf angle and 1000-grain mass of CMS were not significantly affected by the GA3 application for male parent and male to female ratio, while, number of fertile panicles hill-1, panicle mass, seed set, seed yield and harvest index of CMS lines were highly significantly affected. The highest seed yield (2.880 and 2.950 t ha-1) was obtained by CMS line IR69625A using 300 g GA3 ha-1 of male parent Giza 178R with male to female ratio of 2R:14A during both seasons.

In this paper, a comprehensive model to describe the small-signal modulation response of ultra-high performance single- and multi-mode vertical-cavity surface-emitting lasers (VCSELs), with modulation bandwidths exceeding 30 GHz, is presented. Traditionally, utmost simplified dynamic models are used to extract dynamic figures of merit from single-mode edge-emitting lasers. These methods are later on also applied to evaluate the dynamic performance of VCSELs, even though these devices have a very different geometrical layout and modal confinement. However, to understand the dynamic performance of high-speed VCSELs, a model supporting the transverse and longitudinal mode profile, and the driving current inhomogeneity in the active region, is needed. Therefore, multi-mode VCSEL rate equations are established here. Moreover, to access the dynamic figures of merit of these devices, a comprehensive analytical fitting function based on our carrier reservoir splitting approach is derived. Thus, because of the high carrier and photon densities inside these optimized VCSELs, the common carrier reservoir splits up as a result of numerous effects such as mode competition, carrier diffusion and spatial hole burning. These and other effects have a tremendous impact on the small signal modulation response shape and bandwidth, and also on the current distribution profile in the carrier reservoirs. Compared with our recently reported work, this novel model presented includes the effects of gain compression and inhomogeneous current injection between the different lasing modes. Consequently, it is found that the further tuning of our multi-mode VCSEL dynamic model, to include these effects, yields a more physical and consistent figures of merit of high-performance VCSELs.

The operations of multilane roundabouts, especially three-lane roundabouts, are unique and more complicated than any other type of roundabouts. This study aims to analyze driver behavior and estimate the critical gap at three-lane roundabouts. Video data were collected at two roundabouts. The analysis identified a pattern of group gap acceptance, where vehicles entering the roundabout from different lanes moved in groups during the same gap. In this case, the decision of vehicles entering from outside lanes greatly depended on the gap acceptance decision of vehicles in the inside lane. Analysis showed that the vast majority of the vehicles accept the gap in groups and the critical gap was estimated accordingly. The study provides a new explanation for the operation at multilane roundabouts. The use of this simple method is recommended when estimating critical gaps for multilane roundabouts.