Characterization of a Coliphage AS1 isolated from sewage effluent in Pakistan

The emergence of multi-drug resistant (MDR) bacterial strains, which are posing a global health threat has developed the interest of scientists to use bacteriophages instead of conventional antibiotics therapy. In light of an increased interest in the use of phage as a bacterial control agent, the study aimed to isolate and characterize lytic phages from sewage effluent. During the current study, bacteriophage AS1 was isolated from sewage effluent against E.coli S2. The lytic activity of phageAS1 was limited to E.coli S2 strain showing monovalent behavior. The calculated phage titer was 3.5×109 pfu/ml. PhageAS1 was stable at a wide range of pH and temperature. The maximum stability was recorded at 37ºC and pH 7.0, while showing its normal lytic activity at temperature 60ºC and from pH 5.0 to11.0 respectively. At temperature 70ºC, phage activity was somewhat reduced whereas, further increase in temperature and decrease or increase in pH completely inactivated the phage. From the current study, it was concluded that waste water is a best source for finding bacteriophages against multi-drug resistant bacterial strains and can be used as bacterial control agent.

Antimicrobial Formulation of Chrysopogon zizanioides Essential Oil in an Emulsified Lotion for Acne

Acne is a skin condition arising from excess sebum production and microbial overgrowth within the pilosebaceous unit. Several commercial essential oils have shown promising activity against acne-related pathogens. Due to their volatility and thermal instability, the formulation of essential oils into commercial products remains a pharmaceutical challenge. Thus, this study aimed to develop a viable anti-acne topical treatment as an oil-in-water emulsified lotion to overcome these challenges. Chrysopogon zizanioides (vetiver) displayed noteworthy antimicrobial activity with a mean minimum inhibitory concentration of 0.14 mg/mL against Cutibacterium acnes, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. Emulsified lotions containing C. zizanioides were developed through the hydrophilic-lipophilic balance approach. At tested hydrophilic-lipophilic balance values of 8, 9, and 10, C. zizanioides emulsified lotions displayed maximum stability at hydrophilic-lipophilic balance 9 with a minimum change in mean droplet size and polydispersity index of 20.61 and 33.33%, respectively, over 84 days. The C. zizanioides emulsified lotion at optimum hydrophilic-lipophilic balance 9 completely inhibited the growth of C. acnes and killed S. aureus, S. epidermidis, and S. pyogenes within 24 h. Additionally, the lotion retained antimicrobial activity against these test micro-organisms over the 84-day stability test period. Thus, the C. zizanioides emulsified lotion demonstrated physical stability and antimicrobial efficiency, making it an ideal natural product anti-acne treatment.

Estimation of the Accuracy of a Control System with a Fuzzy PID Controller Based on the Approximation of the Static Characteristic of the Controller

The problem of estimating the accuracy of an automatic control system with a fuzzy PID controller is solved. To describe a fuzzy controller, its static characteristic is used, which is approximated by two piecewise-linear and one piecewise-constant sections. This approach makes it possible to study the system as a linear one at each section of the approximated characteristic, and accordingly develop the calculation methods known in control engineering, taking into account the features of the system under consideration. In the article, to calculate the error in the steady state, the theorem on the final value of the original is used. For two different types of second-order control objects — static and astatic — on the basis of this theorem, analytical expressions are obtained that relate the accuracy of the control system with the values of the target and disturbance with a different structure of the controller (P-, PI-, PD-). When conducting experimental studies, the fuzzy PID controller was compared with a linear one tuned by the method of the maximum stability. Research results show that a fuzzy controller ensures the accuracy of the control system is not worse than a linear one, while increasing the dynamics of the system. The analytical expressions presented in the article make it possible to assess the accuracy of a control system with a fuzzy controller and can be used as a technique for adjusting the controller based on the accuracy requirements.

ALGORITHM FOR SELF-TUNING THE PID CONTROLLER

An algorithm for self-tuning the PID controller to the second order systems is proposed in this paper. The proposed self-tuning procedure was developed according to the maximum stability degree criterion, the criterion that permits to achieve the high stability degree, good performance and robustness of the system. According to the proposed algorithm, the controller can be tuned according to the parameters that characterize the process and they can be determinate from the experimental response of the open loop system. To demonstrate the efficiency of proposed procedure of self-tuning the PID controller, the computer simulation was performed and the obtained results were compared with Haeri’s method, maximum stability degree method with iterations and parametrical optimization method. According to the developed algorithm, it was performed the control of the thermal regime in the oven.

Efficacy of antiglide plate in vertical shear fractures of medial malleolus due to supination adduction injury around ankle: a prospective clinical study

Background: Ankle fractures represent 10% of all fractures with an incidence of around 137/100000 population per year, making these the second most common lower limb fractures after hip fractures. Increasing age, obesity and alcohol abuse are the major causal factors for the fractures around the ankle joint. These are typically low energy injuries with the majority occurring due to simple falls or sport. The aim was to open reduction and internal fixation of these with an antiglide plate.Methods: The present prospective study was carried out at government medical college Amritsar, Punjab in 25 patients of same demographic profile, March 2018 to December 2020 after having the clearance of ethical committee. All the patients after careful assessment of the injury both clinically (pain, swelling, deformity, any blisters) and radiologically (type of fracture, that is, vertical shear fracture of medial malleolus) were internally fixed under spinal anesthesia, with an antiglide plate after reduction of the fracture fragments.Results: The results were assessed accordance with Olerud-Molander ankle score (OMAS). We achieved excellent to good results with an average OMAS score of 80/100 in the present study.Conclusions: The open reduction and internal fixation of vertical shear fractures of medial malleolus with an antiglide plate is an effective way of management of these fractures. It ensures maximum stability and more so safeguards against loss of reduction or the implant failure under axial loading and at the same time ensures the timely union of such fractures without any significant complications.

Shrimp Robot Mechanism

The Shrimp rover is highly suitable for planetary exploration missions because of its unconventional wheel order, in-built passive adaptability and good ability to climb obstacles. It is a spatial multi-body system and a multi-variable, multi-parameter coupled non-linear system. Thus, kinematic and dynamic analyses for such systems are complex and time consuming. Long-range robotic missions for Martian exploration imply a high degree of autonomy. The most advanced locomotion concepts are based on wheels or caterpillars (e.g. Sojourner, NASA or Nanokhod, ESA). These rovers have clear advantages regarding power efficiency and complexity if compared with walking robots. However, they still have quite limited climbing abilities. Typically they can only overcome obstacle smaller than their wheel size. In this paper we present Shrimp, an innovative long range rover architecture with 6 motorized wheels. Using a rhombus configuration, the rover has a steering wheel in both, the front and the rear, and two wheels arranged on a bogie on each side. The front wheel has a spring suspension to guarantee optimal ground contact of all wheels at any time. The steering of the rover is realized by synchronizing the steering of the front and rear wheel and the speed difference of the bogie wheels. This allows for high precision maneuvers and even turning on the spot with minimum slip. The use of parallel articulations for the front wheel and the bogies enables to set a virtual centre of rotation at the level of the wheel axis while maintaining a high ground clearance. This insures maximum stability and climbing abilities even for relatively low friction coefficients between the wheel and the ground. This rover is able to passively overcome unstructured obstacles of up to two times its wheel diameter. With this high mobility, this architecture is the perfect candidate for long range planetary missions.

A novel Nb superconducting joint with ultralow resistance fabricated by electron beam welding method for superconducting gravimeter

This paper presents a novel Nb superconducting joint with an ultralow resistance of 7.9 × 10-16 Ω, fabricated using the electron beam welding (EBW) method. After the EBW process, the two Nb filaments formed a single joint with a much larger grain size and smaller grain misorientation. More importantly, the resistance of the EBW Nb joint was nearly one magnitude lower than that of most conventional pressing joint. The ultralow resistance is essential for superconducting gravimeters, which require an extremely low drift rate. The EBW Nb joint allowed the superconducting gravimeter to have a much better performance when applied in the field of structural geology, geodesy, microgravity, and metrology. We believe that the EBW method could be one of the most promising joint fabrication methods for achieving maximum stability (less than 1 μgal/yr).

Utilization of Bitumen, Aggregate and Wax with Rubber Tyre in a Flexible Pavement

With continuous wear and tear actions of rubber tyre on roads, a pile of waste rubber gets accumulated every year and it is posing severe threats to the environment. Due to high temperature in the summers, the road tends to become brittle, which may cause separation of binder in the bituminous road causing heavy cracks, so usage of wax tends to reduce the formation of cracks and improve the flexibility of road. This study aims to examine the effects on properties of the bitumen-aggregate mixture when the aggregates are partially replaced by similar sizes of waste rubber tyre particles and bitumen in the mix are partially replaced by a crumb waste rubber tyre, with partial addition of wax content in the bituminous samples. For this purpose of testing the suitability of using rubber waste in road pavement, Marshall Stability test is conducted on several bituminous mixtures. Varying percentages of rubber tyre, such as 0%, 5%, 10% and 15%, are used with different percentages of bitumen content (4.0, 4.2, 4.4, and 4.6), and varying percentages of paraffin wax (0-5%) is also added in the specimen with rubber and bitumen. This is utilized in obtaining the optimum content of bitumen required for best suitability of flexible pavement as well as to assess the durability and strength of a pavement. This study is performed on various mixtures, for the values of bulk density, air voids, stability value and flow value. The studies show that bitumen content corresponding to the maximum stability value and maximum bulk specific gravity in bituminous mixture, indicating the optimum bitumen percentage that can be replaced with crumb rubber tyre. This paper discusses the partial replacement of both aggregate and bitumen in the bituminous mixture, containing some percentages of paraffin, which can help in improving the serviceability level and assists in enhancing the flexibility and cohesion of road to resist heavy loadings of vehicle.

Effect of three non-axisymmetric stator schemes on compressor performance with distorted inlet

In the boundary layer ingesting propulsion system, the compressor suffers from a non-uniform flow field. The compressor operating with distorted inflow continuously results in the loss of aerodynamic performance and stability margin. In this paper, three non-axisymmetric configurations are described for the stator of a transonic compressor to match the non-uniform flow field. The flow fields with distorted inflow at near stall condition are obtained and analyzed, the effects of the prototype stator and the three non-axisymmetric stators on aerodynamic performance are compared in detail. Results show that the non-axisymmetric stator schemes can effectively improve the stability margin of the transonic compressor and the maximum stability margin is relatively increased by 22.3% in all the three non-axisymmetric stators. The non-axisymmetric stator design is effective on decreasing the aerodynamic losses and improving the performance of the compressor operating with distorted inflow. Overall, the results show that in the design of the non-axisymmetric stator, the adoption of a curved-twisted blade and the increase of cascade solidity have the potential to reduce loss sources caused by distorted inflow.

The Effect of Animal Bone Ash on the Mechanical Properties of Asphalt Concrete

For the sake of enhancing the mechanical properties and durability of asphalt concrete, many studies suggest adding different admixtures, such as waste materials in the form of filler. These admixtures have a significant influence on the performance of asphalt concrete by plying a roll in filling the voids between particles and sometimes as a cementitious material. This study aims to improve the strength of asphalt concrete by adding crushed animal bone to the mix after carbonization at a temperature of 800 Co. Seven different percentages (10, 20, 30, 40, 50, 60, and 100%) of animal bone ash as a replacement for the filler percentage were added to the optimum asphalt concrete mix. A number of tests were conducted on asphalt concrete specimens to measure Marshall stability (MS), Marshall flow value (MF), voids filled with asphalt percentages (VFA), air void percentages (VA), voids in mineral aggregate percentages (VMA), and maximum theoretical specific gravity (GMM). From the results, the maximum stability of 14.85 KN was reached when using animal bone ash of 20% as a partial replacement for the conventionally used filler (limestone). In general, there are some improvements in the physical properties of asphalt concrete with animal bone ash, which can be related to the increase in the bond between the particles of aggregates and the bitumen material. Doi: 10.28991/cej-2021-03091757 Full Text: PDF