Optimal Kinematic Design of a Robotic Lizard using Four-Bar and Five-Bar Mechanisms

Designing a mechanism to mimic the motion of a common house gecko is the objective of this work. The body of the robot is designed using four five-bar mechanisms (2-RRRRR and 2-RRPRR) and the leg is designed using four four-bar mechanisms. The 2-RRRRR five-bar mechanisms form the head and tail of the robotic lizard. The 2-RRPRR five-bar mechanisms form the left and right sides of the body in the robotic lizard. The four five-bar mechanisms are actuated by only four rotary actuators. Of these, two actuators control the head movements and the other two control the tail movements. The RRPRR five-bar mechanism is controlled by one actuator from the head five-bar mechanism and the other by the tail five-bar mechanism. A tension spring connects each active link to a link in the four bar mechanism. When the robot is actuated, the head, tail and the body moves, and simultaneously each leg moves accordingly. This kind of actuation where the motion transfer occurs from body of the robot to the leg is the novelty in our design. The dimensional synthesis of the robotic lizard is done and presented. Then the forward and inverse kinematics of the mechanism, and configuration space singularities identification for the robot are presented. The gait exhibited by the gecko is studied and then simulated. A computer aided design of the robotic lizard is created and a prototype is made by 3D printing the parts. The prototype is controlled using Arduino UNO as a micro-controller. The experimental results are finally presented based on the gait analysis that was done earlier. The forward walking, and turning motion are done and snapshots are presented.Comment: 21 pages, 10 figures, Submitted for iNaCoMM 2023 conferenc

In vitro susceptibility of Mycobacterium tuberculosis to trifluoperazine

The reference strain, Mycobacterium tuberculosis H37Rv, 19 drug-sensitive and 15 drug resistant clinical isolates of M. tuberculosis were tested for their in vitro susceptibility to trifluoperazine (TFP), an antipsychotic drug, by broth dilution method. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of TFP against M. tuberculosis H37Rv were 8 and 32 mg/l, respectively. The distribution of the sensitive and resistant isolates, with respect to the MIC of TFP, was similar. The distribution of the sensitive and resistant isolates, with respect to the MBC of TFP, was different and the difference was statistically significant. The findings suggest that TFP is more bactericidal to drug-resistant isolates than to the sensitive isolates

Experimental investigation and mechanism analysis: Effect of concentration and temperature on the heat transfer characteristics of novel MWCNT-mustard oil nanofluid

ABSTRACT. The bio-oils as alternative lubricating fluid are potential solution for the automotive and industrial mechanical systems. The development of novel renewable and non-toxic bio-oils with better heat transfer distinctiveness will strengthen the economy of farmers in the agricultural based countries. The most innovative approach to improve the heat transfer characteristics of bio-oils is converting it into nanofluids by dispersing nanomaterials which has extremely high heat transfer characteristics. In this study, MWCNT-Mustard oil nanofluids were formulated through ultrasonication and their dispersion stability was estimated through Zeta-potential technique.  The thermal stability of the MWCNT-Mustard oil nanofluids are estimated through thermogravimetric analysis and concentration and temperature dependent density, thermal conductivity and specific heat capacity of MWCNT-Mustard oil nanofluids are also determined and their characteristics are discussed. The heat transfer characteristics of MWCNT-Mustard oil nanofluids observed through the heat pipe test rig at different inlet temperatures, mass flow rate of nanofluids and Reynolds number. The results exhibits that the dispersion of MWCNT enhances the heat transfer characteristics of MWCNT-Mustard oil nanofluids.   KEY WORDS: Non-toxic bio-oils, Nanomaterials, Nanofluids, Thermogravimetric analysis, MWCNT, Mustard oil Bull. Chem. Soc. Ethiop. 2022, 36(3), 675-686.                                                                DOI: https://dx.doi.org/10.4314/bcse.v36i3.1

Reaction of Hydrazine Hydrate with Oxalic Acid: Synthesis and Crystal Structure of Dihydrazinium Oxalate

The reaction of oxalic acid with hydrazine hydrate (in appropriate mole ratio) forms the dihydrazinium oxalate under specific experimental condition. The title compound is a molecular salt containing two discrete hydrazinium cations and an oxalate anion. The oxalate anion is perfectly planar and there is a crystallographic centre of symmetry in the middle of the C-C bond. The C-O bond distances are almost equal indicating the presence of resonance in the oxalate ion. The crystal packing is stabilized by intermolecular N-H…Oand  N-H…Nhydrogen bonds. The oxalate ions are linked together end to end through hydrogen bonds (via N2H5+ ions) and run parallel to the [101] direction. It is interesting to note that each oxalate group in the structure is surrounded by six hydrazinium ions through hydrogen bonding. Similarly, each hydrazinium ion is surrounded by three oxalate and one hydrazinium ion.KEY WORDS: Hydrazine, oxalic acid, dihydrazinium oxalate, crystal structure

Knowledge, attitude, and practices among clinically exposed medical students and interns towards COVID-19 vaccine in a tertiary care hospital, Kanyakumari district: a cross-sectional survey

Background: Several COVID-19 vaccines have been approved against coronavirus disease and its distribution to different countries. The study is mainly done to determine the knowledge, attitude, and practice among clinically exposed medical students and interns toward COVID-19 vaccine.Methods: A cross-sectional study was conducted from June 2022 to August 2022 in a tertiary care hospital. Using questionnaires, the knowledge, attitude, and practice among medical students and interns were assessed, and they were then analysed and categorised accordingly. Then the students were given awareness regarding COVID-19 vaccine.Results: The questionnaires were distributed among students and interns, and responses were collected. A total number of participants (n=300), out of which the majority of responders were second-year students 89 (29.6%). Overall, 39.75% had high-grade knowledge, 43.5% had a positive attitude and 37.5% had good practice regarding the COVID-19 vaccine. The results show that 81.2% of interns had high-grade knowledge, 76.6% possess a positive attitude and 71.9% of good practice and preventive measures towards COVID-19 vaccine.Conclusions: Our study concludes that there were certain gaps in knowledge, attitude, and practice among second and third-year medical students when compared with final-year medical students and interns

Reprinted Article “Factors Associated with Early Failure of Arteriovenous Fistulae for Haemodialysis Access”

AbstractThe radiocephalic arteriovenous fistula remains the method of choice for haemodialysis access. In order to assess their suitability for fistula formation, the radial arteries and cephalic veins were examined preoperatively by ultrasound colour flow scanner in conjunction with a pulse-generated run-off system. Intraoperative blood flow was measured after construction of the fistulae. Post-operative follow-up was performed at various intervals to monitor the development of the fistulae. Radial artery and cephalic vein diameter less than 1.6 mm was associated with early fistula failure. The intraoperative fistula blood flow did not correlate with the outcome of the operation probably due to vessel spasm from manipulation. However, blood flow velocities measured non-invasively 1 day after the operation were significantly lower in fistulae that failed early compared with those that were adequate for haemodialysis. Most of the increase in fistula diameter and blood flow occur within the first 2 weeks of surgery

Optimizing Micro-Turning Parameters during Step Turning Process on Titanium Alloy with RSM

An attempt was made to evaluate and improve the machining parameters of micro-turning titanium alloy with cermet insert on the titanium alloy’s surface roughness. The experiments were done using a strong statistical tool to construct a matrix by utilizing Response Surface Methodology (RSM) and Box-Behnken design for performing the micro turning. Quadratic model was generated to predict the response and also used to appraise the effect of outcomes. The results of the investigation suggest that the cutting feed as well as speed rate are the input elements that have the greatest impact on surface roughness. Numerical with graphical optimization methods are figured out to seek out the optimum method parameters. The subsequent machining conditions lead to minimum surface roughness on speed 2944 rpm, 7.23 µm/rev feed along with 15 µm depth of cut that helps to attain the great surface quality with minimum machining value and at the same time improves the productivity with 86% of optimum desirability rate

Unmanned and autonomous ground vehicle

Unmanned and Autonomous Ground Vehicle (UAGV) is a smart vehicle that capable of doing tasks without the need of human operator. The automated vehicle can work during off and on road navigation and also used in military operation such as detecting bombs, border patrol, carrying cargos, search, rescue etc reducing soldier’s exposure to danger, freeing them to perform other duties. This type of vehicle mainly uses sensors to observe the environment and automatically take decisions on its own in unpredictable situation and with unknown information or pass this information to the operator who control the UAGV through various communication when it requires support. This UAGV can send visual feedbacks to the operator at the ground station. An onboard sensor gives the complete environment of the vehicle as signals to the operator

3-[(Z)-Benzyl­idene]-2,3-dihydro-1,5-benzothia­zepin-4(5H)-one

In the title compound, C16H13NOS, the seven-membered ring adopts a distorted half-chair conformation. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds, forming chains running along the b axis. The crystal packing is further stabilized by C—H⋯O inter­actions

Diagnostic luciferase reporter phage assay for active and non-replicating persistors to detect tubercle bacilli from sputum samples

Diagnosis of latent tuberculosis infection is a myth for want of a simple, direct tool. Simulation of hypoxic environment was done to create a novel hypothetical model for persistence using processed sputum samples. The adaptation of tubercle bacilli to hypoxic environment seems to be influenced by pre-existing clinical status of the patients at the time of sputum collection, resulting in varied growth pattern. Bacilli from 36 samples did not get adapted to latency of which 15 samples were from patients in whom the disease was well established and the tubercle bacilli in them probably did not experience any stress whatsoever. Similarly, 10 of the 37 samples showing the presence of cultivable cells in both aerobic and anaerobic conditions were from patients who had relapsed. The bacilli in these samples had been probably experiencing stress and thus were ready to adapt to the hypoxic environment. Diagnostic luciferase reporter phage assay for non-replicating persistors (DLRPA-NRP) identified 30 additional positives which failed to grow on Lowenstein– Jensen medium. Presence of viable bacilli in these samples was confirmed by reverse transcriptase-PCR (RT-PCR) for 16S rRNA indicating either the improved sensitivity of the assay to detect actively growing bacilli or its ability to detect non-replicating persistors. The utility of LRP assay to detect both dormant and active tubercle bacilli was explored in this work and was optimized using lysis inhibition to diagnose tuberculosis with rapidity, improved sensitivity and specificity. DLRPA-NRP, a rapid growth based assay is thus developed to detect both dormant and actively growing tubercle bacilli