New endoperoxides highly active in vivo and in vitro against artemisinin-resistant Plasmodium falciparum

Background: The emergence and spread of Plasmodium falciparum resistance to artemisinin-based combination therapy in Southeast Asia prompted the need to develop new endoperoxide-type drugs. Methods: A chemically diverse library of endoperoxides was designed and synthesized. The compounds were screened for in vitro and in vivo anti-malarial activity using, respectively, the SYBR Green I assay and a mouse model. Ring survival and mature stage survival assays were performed against artemisinin-resistant and artemisinin-sensitive P. falciparum strains. Cytotoxicity was evaluated against mammalian cell lines V79 and HepG2, using the MTT assay. Results: The synthesis and anti-malarial activity of 21 new endoperoxide-derived compounds is reported, where the peroxide pharmacophore is part of a trioxolane (ozonide) or a tetraoxane moiety, flanked by adamantane and a substituted cyclohexyl ring. Eight compounds exhibited sub-micromolar anti-malarial activity (IC50 0.3–71.1 nM), no cross-resistance with artemisinin or quinolone derivatives and negligible cytotoxicity towards mammalian cells. From these, six produced ring stage survival < 1% against the resistant strain IPC5202 and three of them totally suppressed Plasmodium berghei parasitaemia in mice after oral administration. Conclusion: The investigated, trioxolane–tetrazole conjugates LC131 and LC136 emerged as potential anti-malarial candidates; they show negligible toxicity towards mammalian cells, ability to kill intra-erythrocytic asexual stages of artemisinin-resistant P. falciparum and capacity to totally suppress P. berghei parasitaemia in mice.info:eu-repo/semantics/publishedVersio

Experimental investigations of electrodeposited Zn-Ni, Zn-Co, and Ni-Cr-Co-based novel coatings on AA7075 substrate to ameliorate the mechanical, abrasion, morphological, and corrosion properties for automotive applications

The aluminum (Al) alloy AA7075 is widely used in various industries due to its high strength-to-weight ratio, which is comparable and replaceable to steel in many applications. However, it has poor resistance to wear and corrosion compared to other Al alloys. The conventional pressure die coating with Cr and cadmium has led to premature failure while the load is applied. It is indeed to develop a novel coating method to improve the mechanical, wear, and corrosion properties of AA7075 Al alloy. In the present investigation, the binary and ternary metals such as zinc-nickel (Zn-Ni), zinc-cobalt (Zn-Co), and nickel-chromium-cobalt (Ni-Cr-Co) are electroplated on the substrate material (AA7075). In order to ensure optimal coating adhesion, the surface of the substrate material was pre-treated with laser surface treatment (LST). The mechanical and corrosion studies have been carried out on the uncoated and coated materials. It is observed from the findings that the ternary coating has higher wear resistance than the binary-coated material. The ternary coating has 64% higher resistance in the non-heat-treated status and 67% higher resistance in the heat-treated condition compared to the uncoated specimens. The tensile strength (MPa) of Ni-Cr-Co on AA7075 pressure die casting (PDC) is higher than the other deposits (582.24 of Ni-Cr-Co > 566.07 of Zn-Co > 560.05 of Zn-Ni > 553.64 of uncoated condition). The presence of a crystalline structure with the high alignment of Co and Ni atoms could significantly improve the corrosion resistance of Ni-Cr-Co coatings on AA 7075 PDC substrates when compared to binary coatings. The scanning electron microscopy (SEM) images, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy findings on the coated materials have been corroborated with the analyses on mechanical and corrosion properties. The XRD analysis of the Zn-Ni binary coating has reported that the diffraction peaks of γ-NiZn3 (831), γ-Ni2Zn11 (330), and 631 with 2θ values 38, 43, and 73° are confirming the presence of Zn-Ni binary deposit on AA7075 PDC substrate. The XRD pattern of Zn-Co-coated material has revealed that the presence of three strong peaks such as Zn (110), Co (111), and CoZn (211) and two feeble peaks such as ϵ-CoZn3 (220) and ϵ-CoZn3 (301) are clearly visible. The XRD pattern of Ni-Cr-Co ternary coating has exhibited that the Ni-Cr-Co ternary deposit is a solid solution with a body-centered cubic structure due to the formation peaks at lattice plane such as (110), (220), and (210) with a crystal lattice constant of 2.88 A°. The SEM image for both the binary- and ternary-coated materials has exhibited that the deposited surface has displayed many shallow pits due to hitting by progressive particles. The SEM image has illustrated the presence of Zn-Ni atoms with smaller globular structure. The surface morphology of binary Zn-Co coating on the PDC AA7075 substrate has unveiled the evenly distributed dot-like structure and submerged Co particles in the galaxy of Zn atoms. To understand the effectiveness of bonding by laser texturing, cross-section SEM has been carried out which furthermore revealed the effective adhesion of Ni-Cr-Co on AA7075 PDC; this could also be the reason for the enhancement of microhardness, wear, and corrosion resistance of the said coating. © 2023 the author(s), published by De Gruyter

Cryo-laser synergy: Enhancing metallurgical and mechanical excellence in Inconel 59-AISI 904L joints

This study evaluates the compatibility of dissimilar welding between Inconel 59 and Austenitic Stainless Steel (AISI 904L) using CO₂ Laser Beam Welding. The investigation includes macro and microstructure analysis, mechanical property evaluation, and the effects of cryogenic treatment. Weld geometry was assessed macroscopically, confirming process feasibility. Microscopic analysis revealed fine equiaxed dendrites in the fusion zone with minimal secondary phase formation. XRD phase analysis confirmed phase stability, while residual stress analysis indicated reduced tensile stress in the fusion zone and compressive stress in adjacent regions. The fusion zone exhibited an average hardness of 236 HV, attributed to the refined dendritic structure. Cryogenic treatment improved weld performance, with tensile strength increasing by 5.5 % in shallow mode and 15.3 % in deep mode, alongside a 4.6 % enhancement in impact strength in deep cryogenic conditions. These results validate the feasibility of dissimilar welding between Alloy 59 and AISI 904L for applications requiring high strength and temperature resistance

Low Power and Efficient Floating-Point Architecture for Division and Square Root

Abstract The modern processor requires multiple dedicates, fully pipelined architecture uses instructional level parallelism. So, this pipeline is very important in it. The proposed system is implemented using the fully pipelined architecture FPU in FPGA’s. Square root and division have many complications in DSP but it is important to implement in FPGA because it is so tough. Some of them will not implement the add and multiply components when compared to the slow or large which will match the real time applications. In every clock cycle, pipeline should have the capability of accepting the square root and divider. In single precision floating point Verilog code is written and implemented using spartan 6 FPGA for sqrt/division. The operation latency and issue rate have 18 clock cycles and 15 clock cycles. It uses many adders/subtractors in other high pipelined implementations. The operation latency and issue rate have 15 clock cycles and 1 clock cycles. It reduces power dissipation. It has some advantages like area utilization will be less and latency bound.</jats:p

Biological Activities of Schiff Base and Its Complexes: A Review,

ABSTRACT Schiff bases are versatile ligands which are synthesized from the condensation of primary amines with carbonyl groups. These compounds are very important in medicinal and pharmaceutical fields because of their wide spectrum of biological activities. Most of them show biological activities such as antibacterial, antifungal as well as antitumor activity. Transition metal complexes derived from the Schiff base ligands with biological activity have been widely studied. This review summarizes the synthesis and biological activities of Schiff bases and its complexes

Effect of constant current and pulsed current gas tungsten arc welding process on microstructure and mechanical properties of superalloy 59 joints

Abstract This research paper investigates the microstructure, microsegregation and mechanical behaviour of Ni-based superalloy 59 which is an important candidate in the pollution control application. The weld joints were produced with continuous current gas tungsten arc welding (CCGTAW) and pulsed current gas tungsten arc welding (PCGTAW) by applying both autogenous mode and filler wire ERNiCrMo-13. Weld flaws and weld aspect ratio of weld joints were identified using a macro analysis. An optical microscope (OM) and scanning electron microscope (SEM) were used to examine the microstructure of the welded joints. PCGTA weldments exposed refined grain structure, reduced heat-affected zone and narrow weld bead compared to CCGTAW. Microsegregation of the alloying elements at the weld center (WC) and weld interface (WI) was examined using Energy Dispersive x-ray spectroscopy (EDS). The findings of the metallurgical characterisation proved that the PCGTA weldments offer minimal microsegregation at the interdendritic region in comparison to CCGTA weldments. X-Ray Diffraction (XRD) examination reveals that there is a 16.7% enhancement in grain refinement in the autogenous mode and a 17.4% improvement in the filler wire ERNiCrMo-13 when switching from CCGTA to PCGTA welding. Tensile, Charpy impact and microhardness tests were used to assess the strength, toughness and hardness of the weld joints. Weld joints fabricated by PCGTAW offers higher tensile strength (∼1.4 to 1.6%), higher toughness (∼4.4 to 5.4%), and higher hardness (∼4.8 to 7.7%) than CCGTAW weld joints.</jats:p

Analysis of Physical and Mechanical Properties of A3003 Aluminum Honeycomb Core Sandwich Panels

The demand for lightweight structures made of sandwich panels is ever increasing in many Industrial sectors. Numerous research efforts have been taken by various researchers in this area in terms of weight and cost reduction. Sandwich panel is a composite structure and it is an excellent alternative material in place of weight reduction without sacrificing its strength and stiffness characteristics. The geometrical characteristics of honeycomb core sandwich panels as well as their physical and mechanical properties such as compressive strength, flexural stiffness, core shear moduli, shear strength and stiffness are analyzed. The sandwich panels are available in various shapes and sizes to the service requirement. The commercially available sandwich panels have different core materials such as foams, FRPs and metallic and non metallic materials. The structure of the core typically varies as truss type and honeycomb. The face sheets and the core materials are bonded using thermo-set resins.</jats:p