Influence of Leadership and Employee Benefits to the Quality of Employees in Production

The purpose of this study is analysing leadership has positive effect to the quality of employee in production at PDAM of Surakarta and employee benefit has positive effect to the quality of employee in production at PDAM of Surakarta. This research is quantitative, by taking samples at PDAM of Surakarta, Central Java, Indonesia. The study population and sample as many as 400 employees were taken by 40 employees. The technique of collecting data using questionnaires. The data analysis technique used is multiple linear regression analysis. The results obtained showed that: Leadership has positive effect to the quality of employee in production at PDAM of Surakarta and employee benefit has positive effect to the quality of employee in production at PDAM of Surakarta

The crystal structure of Pneumolysin at 2.0 Å resolution reveals the molecular packing of the pre-pore complex

Pneumolysin is a cholesterol-dependent cytolysin (CDC) and virulence factor of Streptococcus pneumoniae. It kills cells by forming pores assembled from oligomeric rings in cholesterol-containing membranes. Cryo-EM has revealed the structures of the membrane-surface bound pre-pore and inserted-pore oligomers, however the molecular contacts that mediate these oligomers are unknown because high-resolution information is not available. Here we have determined the crystal structure of full-length pneumolysin at 1.98 Å resolution. In the structure, crystal contacts demonstrate the likely interactions that enable polymerisation on the cell membrane and the molecular packing of the pre-pore complex. The hemolytic activity is abrogated in mutants that disrupt these intermolecular contacts, highlighting their importance during pore formation. An additional crystal structure of the membrane-binding domain alone suggests that changes in the conformation of a tryptophan rich-loop at the base of the toxin promote monomer-monomer interactions upon membrane binding by creating new contacts. Notably, residues at the interface are conserved in other members of the CDC family, suggesting a common mechanism for pore and pre-pore assembly

Network-Based Detection and Prevention System against DNS-Based Attacks

Individuals and organizations rely on the Internet as an essential environment for personal or business transactions. However, individuals and organizations have been primary targets for attacks that steal sensitive data. Adversaries can use different approaches to hide their activities inside the compromised network and communicate covertly between the malicious servers and the victims. The domain name system (DNS) protocol is one of these approaches that adversaries use to transfer stolen data outside the organization\u27s network using various forms of DNS tunneling attacks. The main reason for targeting the DNS protocol is because DNS is available in almost every network, ignored, and rarely monitored. In this work, the primary aim is to design a reliable and robust network-based solution as a detection system against DNS-based attacks using various techniques, including visualization, machine learning techniques, and statistical analysis. The network-based solution acts as a DNS proxy server that provides DNS services as well as detection and prevention against DNS-based attacks, which are either embedded in malware or used as stand-alone attacking tools. The detection system works in two modes: real-time and offline modes. The real-time mode relies on the developed Payload Analysis (PA) module. In contrast, the offline mode operates based on two of the contributed modules in this dissertation, including the visualization and Traffic Analysis (TA) modules. We conducted various experiments in order to test and evaluate the detection system against simulated real-world attacks. Overall, the detection system achieved high accuracy of 99.8% with no false-negative rate. To validate the method, we compared the developed detection system against the open-source detection system, Snort intrusion detection system (IDS). We evaluated the two detection systems using a confusion matrix, including the recall, false-negatives rate, accuracy, and others. The detection system detects all case scenarios of the attacks while Snort missed 50% of the performed attacks. Based on the results, we can conclude that the detection system is significant and original improvement of the present methods used for detecting and preventing DNS-based attacks

Investigation of UV and IR Laser Processing of Single- Crystalline 4H:SiC and Characterisation of Laser Grown Graphene Derivatives

The formation of graphene (G) on the surface of silicon carbide (SiC) has gathered interest over recent years as a potential component in high power nano and microdevices. However, it is still in the early stages of research, therefore there are many challenges to overcome. Among the existing problems, the formation of good quality graphene/SiC is one of the most critical factors that determine the behaviour of this heterostructure. Here we report a full study of the formation of graphene and its derivative structures on SiC using different laser systems with different controlled irradiation conditions.Laser ablation experiments on polished 4H-SiC wafers using a 193 nm ArF laser over a fluence range of 0.3Jcm−2–5Jcm−2 are reported. An onset of material modification was measured at a laser fluence of 925 ± 80 mJcm−2, and a concomitant etch rate of ∼200 pm per pulse. Laser ablation sites have been analysed using optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman microscopy and white light interferometry (WLI). Different surface modifications were observed. The influences of the laser fluence, number of pulses, and scanning velocity on the position of the microchannel are discussed. At a laser fluence in the region of 1.0 Jcm−2, the irradiated site removed material forming a uniform crater. At a higher laser fluence, in the region of 2.7 Jcm−2, nodule-like structures form on the base of the ablation crater. An increased fluence led to a smoother surface with higher etched depth and ripple formation. The dissociation of laser irradiated 4H-SiC was discussed. Graphene oxide (GO) and reduced graphene oxide (rGO) formed on the SiC surface by 193 nm laser- induced high-temperature thermal decomposition of the SiC substrate. The decomposition resulted in the presence of silicon (Si), especially on the edge of the irradiated site.Graphene formation on the 4H:SiC surface by high power CO2 laser. Two distinct ablation threshold energies of 4.3 mJ and 73 mJ were found. The etch rate was dependent on the applied pulse duration, laser power, the scanning velocity and the number of pulses. High temperature thermal decomposition of the SiC substrate was achieved with a CO2 laser over a power range of 1-30 W. The structure was different from the structure obtained from the UV laser irradiated samples. More rough surfaces were prepared with small islands of graphene, GO and rGO on SiC in addition to the ripples. Monolayer and Multilayer graphene was also achieved. The laser-induced surface decomposition of the SiC was controlled spatially. The processing was held at room temperature, and the operation carried out in either a vacuum chamber or at atmospheric pressure. A fast graphene growth rate was achieved. This method is achievable, scalable and compatible with semiconductors technology due to the onsite direct writing of graphitic structure formed by the laser. This method is cost-effective as it does not necessitate SiC pre- treatment, there is no need for a processing vacuum chamber, and it can be achieved on the nano/microsecond time scale.Analytical and Finite element simulations using COMSOLTM MetaphySiCs, 5.3 have been used to calculate laser-induced temperature rise of 4H-SiC as a function of laser fluence. The simulated temperature was always less the temperature anticipated analytically. The 193 nm laser fluence required to reach the melting points of silicon, silicon carbide, and carbon, have been calculated and correspond to ∼0.97, 1.95 and 2.6 Jcm−2, respectively. Extreme heating and cooling rates controlled the growing process of graphene and its derivatives. The CO2 laser-induced temperature rise was also estimated. The CO2 laser acted as a heat source for the SiC. High power was used to reach the high temperature needed to decompose the SiC. Pulse duration also played a significant role in controlling the temperature and the depth distribution inside the SiC.This work reports the graphene formation on the surface of SiC by laser-induced thermal decomposition for electrical characterisation. Current-voltage (I-V) measurements show a decrease of the electrical resistance per unit length by nine orders of magnitude. The lowest resistance per unit length was obtained using a laser fluence of ~1.5 Jcm-2, a pulse repetition frequency of 10 Hz and using a sample translation speed of 0.01 mms-1. Temperature simulations have been performed using the finite element method (FEM) to assist in understanding the dissociation mechanisms of SiC and hence optimise the experimental variables. 2D axis-symmetric FEM calculations predict a surface temperature of ~2500K at a laser fluence of 1.5 Jcm-2. Laser-irradiated 4H:SiC is an efficient and controllable method of producing highly reproducible electrically conducting tracks. An increase in the conductivity was observed when the graphitic structure was produced with the CO2 laser. However, the conductivity was less than the graphitic structure produced by the 193 nm laser. It is expected that the different graphene interfaces, including Ohmic contact and Schottky contact, was created

Gas Seperation through Hollow Fiber and Spiral Wound Membranes

Computational fluid dynamics simulations are conducted for multicomponent fluid flows over banks of hollow fiber membranes. The hollow fiber membrane systems is considered here for gas separation applications. Separation of carbon dioxide (CO2) from methane (CH4) is studied using hollow fiber membranes packed in different arrangements. The membrane surface is considered as a functional surface where the mass flux and concentration of each species are coupled and are determined as a function of the local partial pressures, the permeability, and the selectivity of the membrane. k-ω Shear Stress Transport (k-ω SST) turbulent model is employed to study the mixture flow over banks of hollow fiber membrane for values of the Reynolds number up to 1000. The flow structure around the hollow fiber membranes dominates the performance of the separation process. This study demonstrates clearly that good mixing in the bank of hollow fiber membranes enhances the separation performance. The results show that hollow fiber membrane module with staggered arrangement performs much better than that with inline arrangement. For the spiral wound membrane, it has been shown that membrane performance could be greatly enhanced by momentum mixing in the feed channel induced by spacers. Square shaped spacer will be considered in the inline arrangement for values of the Reynolds number up to 500. In order to validate the turbulence model transient flow simulations are conducted using lattice Boltzmann method. The lattice Boltzmann method to simulate flow in the geometries related to the spiral wound membrane modules is developed by our research group at Lehigh. Two dimensional nine velocity directional, D2Q9, lattice arrangement with multi-relaxation time (MRT) lattice Boltzmann method is used to simulate transient flow field while single relaxation time (SRT) lattice Boltzmann method. Simulations are performed to determine concentration field for values of Re up to 300. The bounding surfaces are treated as impermeable walls for simulations conducted using the lattice Boltzmann method. The results predicted by the lattice Boltzmann method and the SST turbulence model agree well, validating the turbulence model and the numerical method

Advances in Regenerative Medicine: Stem Cell Therapy and Tissue Engineering

Regenerative medicine, with its core in stem cell therapy and tissue engineering, is revolutionizing healthcare by offering novel solutions for tissue repair, organ regeneration, and disease treatment. This paper explores the advancements in stem cell research, highlighting their ability to differentiate into various cell types and their applications in treating cardiovascular diseases, neurodegenerative disorders, diabetes, and more. Additionally, the paper delves into tissue engineering techniques, such as scaffold design, bioreactors, and 3D bioprinting, that are shaping the future of organ replacement and personalized medicine. While these technologies show immense promise, ethical concerns surrounding embryonic stem cells and technical challenges such as vascularization remain critical issues. Nonetheless, the potential rewards—curing previously untreatable diseases, addressing organ shortages, and reducing healthcare costs—are driving ongoing research and innovation. As these technologies evolve, regenerative medicine is poised to redefine human healing, offering unprecedented opportunities for future healthcare

Computational Study of Gas Separation Using Reverse Osmosis Membranes

Hollow fiber (HFM) and spiral wound membrane modules are among the most common separation devices employed in reverse osmosis gas separation and desalination applications. Three-dimensional steady state computational fluid dynamics (CFD) simulations are carried out to study flow past hollow fiber membrane banks (HFMB). This work focuses on enhancing the membrane performance by improving the momentum mixing in the feed channel by placing hollow fiber membranes in different arrangements and spacings. The current study investigates the effects of flow behavior on membrane performance during binary mixture separations. Carbon dioxide (CO_2) removal from methane (CH_4) is examined in the staggered and inline arrangement of HFMs. The most common HFM module arrangement in industrial applications is the axial flow configuration. However, this work focuses on the radial crossflow configuration. Membrane surface is treated as a functional boundary where the suction rate and concentration of each species are coupled and are functions of the local partial pressures, the permeability, and the selectivity of the membrane. The CFD simulations employed the turbulent k-ω Shear Stress Transport (k-ω SST) model to study membrane performance for a wide range of the Reynolds number. The efficiency of the inline and staggered arrangements in the separation module is evaluated by the coefficient of performance and the rate of mass flow per unit area of CO2 passing across the membrane surface. This work demonstrates that the module with staggered arrangements outperforms the module with inline arrangements.This study also considers a three-dimensional hybrid separation module consisting of two parallel spiral wound membranes bounding the feed channel that contains hollow fiber membranes with various arrangements. The results of numerical simulations indicate that the hybrid membrane system with a net hollow fiber membrane provides profoundly improved membrane flux performances for both spiral wound membranes and HFMs. The removal of CO2 from CH4 is enhanced by the presence of net hollow fiber membranes in the feed channel.This work also numerically characterizes flux performance of the membrane, concentration polarization, and potential fouling sites in the reverse osmosis desalination module, which contains hollow fiber membranes arranged in an inline and a staggered configuration. An accurate membrane flux model, the solution-diffusion model, is employed. Hollow fiber membrane surface is treated as a functional boundary where the rate of water permeation is coupled with local concentration along the membrane surface. The rate of water permeation increases and concentration polarization decreases as the feed flow rate is increased. Hollow fiber membranes in the staggered geometry perform better than those in the inline geometry.It is proven by the present study that gas separation and desalination modules containing hollow fiber membranes should be designed and optimized by careful consideration of their configurations

Effect of combined Ce and Er Addition on Solidification, Microstructure of the Al-7Si-alloy

This paper highlights the effects of the additions of two rare earth elements (REEs) (Ce and Er) on microstructure and to investigate the characteristic temperatures during solidification of the modified alloy. Five changes of Al-7Si alloys with xEr+xCe additions (x=0.15, 0.25, 0.4, 0.5 and 0.75) were produced by casting technique via the solidification parameters examined using computer-aided cooling curve thermal analysis (CA-CCTA). The thermal analysis tests were carried out for each one by using a thermal analysis system that includes (K-type Thermocouple, EPAD-TH8-K, EPAD-Baes2 and Laptop with Dewesoft-7.5-Lt). To estimate the change in microstructure and solidification as a result of adding (Ce+Er) additions, the obtained result showed that the growth TG Al-Phase and nucleation TN Al-Phase temperatures decreased to lower temperatures 614.7°C and 615.5°C respectively as the amount Ce, Er increased

Climate change and water resources in arid regions : uncertainty of the baseline time period

Recent climate change studies have given a lot of attention to the uncertainty that stems from general circulation models (GCM), greenhouse gas emission scenarios, hydrological models and downscaling approaches. Yet, the uncertainty that stems from the selection of the baseline period has not been studied. Accordingly, the main research question is as follows: What would be the differences and/or the similarities in the evaluation of climate change impacts between the GCM and the delta perturbation scenarios using different baseline periods? This article addresses this issue through comparison of the results of two different baseline periods, investigating the uncertainties in evaluating climate change impact on the hydrological characteristics of arid regions. The Lower Zab River Basin (Northern Iraq) has been selected as a representative case study. The research outcomes show that the considered baseline periods suggest increases and decreases in the temperature and precipitation (P), respectively, over the 2020, 2050 and 2080 periods. The two climatic scenarios are likely to lead to similar reductions in the reservoir mean monthly flows, and subsequently, their maximum discharge is approximately identical. The predicted reduction in the inflow for the 2080–2099 time period fluctuates between 31 and 49% based on SRA1B and SRA2 scenarios, respectively. The delta perturbation scenario permits the sensitivity of the climatic models to be clearly determined compared to the GCM. The former allows for a wide variety of likely climate change scenarios at the regional level and are easier to generate and apply so that they could complement the latter