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Degradation behavior of biodegradable Fe35Mn alloy stents

Sing NB, Mostavan A, Hamzah E, Mantovani D, Hermawan H

J Biomed Mater Res B Appl Biomater, 2015 Apr;103(3):572-7.
PMID: 24954069 DOI: 10.1002/jbm.b.33242

This article reports a degradation study that was done on stent prototypes made of biodegradable Fe35Mn alloy in a simulated human coronary arterial condition. The stent degradation was observed for a short-term period from 0.5 to 168 h, which simulates the early period of stenting procedure. Potentiodynamic polarization and electrochemical impedance spectroscopy were used to quantify degradation rate and surface property of the stents. Results showed that signs of degradation were visible on both crimped and expanded stents after 1 h of test, mostly located on the stent's curvatures. The degradation rate of stent was higher compared to that of the original alloy, indicating the surface altering effect of stent fabrication processing to degradation. A single oxide layer was formed and detected as a porous structure with capacitive behavior. Expanded stents exhibited lower polarization resistance compared to the nonexpanded ones, indicating the cold work effect of expansion procedure to degradation.

Matched MeSH terms: Alloys/chemistry*
The effect of oleic acid stabilizer on the surface properties of bimetallic PtNi catalysts

Abu Bakar NH, Abu Bakar M, Bettahar MM, Ismail J, Monteverdi S

J Nanosci Nanotechnol, 2013 Jul;13(7):5034-43.
PMID: 23901527

A detailed study on the surface properties of oleic acid-stabilized PtNi nanoparticles supported on silica is reported. The oleic acid-stabilized PtNi nanoparticles were synthesized using NaBH4 as the reducing agent at various temperatures and oleic acid concentrations, prior to incorporation onto the silica support. X-ray diffraction studies of the unsupported oleic acid-stabilized PtNi particles revealed that the PtNi existed as alloys. Upon incorporation onto silica support, surface properties of the catalysts were investigated using H2-temperature reduction (H2-TPR), H2-temperature desorption (H2-TPD) and H2-chemisorption techniques. It was found that for the bimetallic catalysts, no oxides or very little oxidation occurred. Furthermore, these catalysts exhibited both Pt and Ni active sites on its surface though the availability of Ni active sites was dominant. A comparison of the surface properties of these materials with those prepared without oleic acid in our previous work [N. H. H. Abu Bakar et al., J. Catal. 265, 63 (2009)] and how they affect the hydrogenation of benzene is also discussed.

Matched MeSH terms: Alloys/chemistry
Corrosion and bioactivity performance of graphene oxide coating on TiNb shape memory alloys in simulated body fluid

Saud SN, Hosseinian S R, Bakhsheshi-Rad HR, Yaghoubidoust F, Iqbal N, Hamzah E, et al.

Mater Sci Eng C Mater Biol Appl, 2016 Nov 01;68:687-694.
PMID: 27524069 DOI: 10.1016/j.msec.2016.06.048

In the present work, the microstructure, corrosion, and bioactivity of graphene oxide (GO) coating on the laser-modified and -unmodified surfaces of TiNb shape memory alloys (SMAs) were investigated. The surface morphology and chemical composition was examined using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The surface modification was carried out via a femtosecond laser with the aim to increase the surface roughness, and thus increase the adhesion property. FE-SEM analysis of the laser-treated Ti-30at.% Nb revealed the increase in surface roughness and oxygen/nitrogen containing groups on the Ti-30at.% Nb surface after being surface modified via a femtosecond laser. Furthermore, the thickness of GO was increased from 35μm to 45μm after the surface was modified. Potentiodynamic polarisation and electrochemical impedance spectroscopy studies revealed that both the GO and laser/GO-coated samples exhibited higher corrosion resistance than that of the uncoated TiNb SMA sample. However, the laser/GO-coated sample presented the highest corrosion resistance in SBF at 37°C. In addition, during soaking in the simulated body fluid (SBF), both the GO and laser/GO coating improved the formation of apatite layer. Based on the bioactivity results, the GO coating exhibited a remarkable antibacterial activity against gram-negative bacteria compared with the uncoated. In conclusion, the present results indicate that Ti-30at.% Nb SMAs may be promising alternatives to NiTi for certain biomedical applications.

Matched MeSH terms: Alloys/chemistry*
Force delivery of NiTi orthodontic arch wire at different magnitude of deflections and temperatures: A finite element study

Razali MF, Mahmud AS, Mokhtar N

J Mech Behav Biomed Mater, 2018 Jan;77:234-241.
PMID: 28954242 DOI: 10.1016/j.jmbbm.2017.09.021

NiTi arch wires are used widely in orthodontic treatment due to its superelastic and biocompatibility properties. In brackets configuration, the force released from the arch wire is influenced by the sliding resistances developed on the arch wire-bracket contact. This study investigated the evolution of the forces released by a rectangular NiTi arch wire towards possible intraoral temperature and deflection changes. A three dimensional finite element model was developed to measure the force-deflection behavior of superelastic arch wire. Finite element analysis was used to distinguish the martensite fraction and phase state of arch wire microstructure in relation to the magnitude of wire deflection. The predicted tensile and bending results from the numerical model showed a good agreement with the experimental results. As contact developed between the wire and bracket, binding influenced the force-deflection curve by changing the martensitic transformation plateau into a slope. The arch wire recovered from greater magnitude of deflection released lower force than one recovered from smaller deflection. In contrast, it was observed that the plateau slope increased from 0.66N/mm to 1.1N/mm when the temperature was increased from 26°C to 46°C.

Matched MeSH terms: Dental Alloys/chemistry*
Processing and properties optimisation of carbon nanofibre-reinforced magnesium composites for biomedical applications

Tuminoh H, Hermawan H, Ramlee MH

J Mech Behav Biomed Mater, 2022 Nov;135:105457.
PMID: 36116340 DOI: 10.1016/j.jmbbm.2022.105457

In the last decade, magnesium alloys have been considered as absorbable metals for biomedical applications, while some have reached their clinical use as temporary bone implants. However, their widespread use is still limited by its strength and degradability. One way of improvement can be done by reinforcing magnesium alloys with carbon nanofibres to form composites. This work aims at developing carbon nanofibre-reinforced magnesium-zinc (Mg-Zn/CNF) composites with optimum strength and degradability while ensuring their biocompatibility. A response surface method was used to determine their optimum process parameters (composition, compaction pressure, and sintering temperature), and analyse the resulting properties (elastic modulus, hardness, weight loss, and cytocompatibility). Results showed that the optimal parameters were reached at 1.8% of CNF, 425 MPa of compaction pressure, and 500 °C of sintering temperature, whereby it gave an elastic modulus of 5 GPa, hardness of 60 Hv, and a weight loss of 51% after three days immersion in PBS. The composites exhibited a hydrophobic surface that controlled the liberation of Mg2+ and Zn2+ ions, leading to more than 70% osteoblast cells viability up to seven days of incubation. This study can also serve as a starting point for future researchers interested in finding methods to fabricate Mg-Zn/CNF composites with high mechanical characteristics, corrosion resistance, and biocompatibility.

Matched MeSH terms: Alloys/chemistry
Green synthesis of silver and copper nanoparticles using ascorbic acid and chitosan for antimicrobial applications

Zain NM, Stapley AG, Shama G

Carbohydr Polym, 2014 Nov 4;112:195-202.
PMID: 25129735 DOI: 10.1016/j.carbpol.2014.05.081

Silver and copper nanoparticles were produced by chemical reduction of their respective nitrates by ascorbic acid in the presence of chitosan using microwave heating. Particle size was shown to increase by increasing the concentration of nitrate and reducing the chitosan concentration. Surface zeta potentials were positive for all nanoparticles produced and these varied from 27.8 to 33.8 mV. Antibacterial activities of Ag, Cu, mixtures of Ag and Cu, and Ag/Cu bimetallic nanoparticles were tested using Bacillus subtilis and Escherichia coli. Of the two, B. subtilis proved more susceptible under all conditions investigated. Silver nanoparticles displayed higher activity than copper nanoparticles and mixtures of nanoparticles of the same mean particle size. However when compared on an equal concentration basis Cu nanoparticles proved more lethal to the bacteria due to a higher surface area. The highest antibacterial activity was obtained with bimetallic Ag/Cu nanoparticles with minimum inhibitory concentrations (MIC) of 0.054 and 0.076 mg/L against B. subtilis and E. coli, respectively.

Matched MeSH terms: Alloys/chemical synthesis; Alloys/pharmacology
Full-arch metal-resin cement- and screw-retained provisional restoration for immediately loaded implants

Baig MR, Rajan G

J Oral Implantol, 2010;36(3):219-23.
PMID: 20553176 DOI: 10.1563/AAID-JOI-D-09-00048

Abstract This article describes the clinical and laboratory procedures involved in the fabrication of laboratory-processed, provisional, screw-retained, implant-supported maxillary and mandibular fixed complete dentures incorporating a cast metal reinforcement for immediate loading of implants. Precise fit is achieved by intraoral luting of the cast frame to milled abutments. Effective splinting of all implants is attained by the metal substructure and retrievability is provided by the screw-retention of the prosthesis.

Matched MeSH terms: Chromium Alloys/chemistry; Dental Alloys/chemistry
Improved wear resistance of functional diamond like carbon coated Ti-6Al-4V alloys in an edge loading conditions

Choudhury D, Lackner JM, Major L, Morita T, Sawae Y, Bin Mamat A, et al.

J Mech Behav Biomed Mater, 2016 06;59:586-595.
PMID: 27085502 DOI: 10.1016/j.jmbbm.2016.04.004

This study investigates the durability of functional diamond-like carbon (DLC) coated titanium alloy (Ti-6Al-4V) under edge loading conditions for application in artificial hip joints. The multilayered (ML) functional DLC coatings consist of three key layers, each of these layers were designed for specific functions such as increasing fracture strength, adapting stress generation and enhancing wear resistance. A 'ball-on-disk' multi-directional wear tester was used in the durability test. Prior to the wear testing, surface hardness, modulus elasticity and Raman intensity were measured. The results revealed a significant wear reduction to the DLC coated Ti-6Al-4V disks compared to that of non-coated Ti-6Al-4V disks. Remarkably, the counterpart Silicon Nitride (Si3N4) balls also yielded lowered specific wear rate while rubbed against the coated disks. Hence, the pairing of a functional multilayered DLC and Si3N4 could be a potential candidate to orthopedics implants, which would perform a longer life-cycle against wear caused by edge loading.

Matched MeSH terms: Alloys
Determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys by atomic-absorption spectrophotometry

Chong C

Talanta, 1986 Jan;33(1):91-4.
PMID: 18964038

A simple atomic-absorption spectrophotometry method is described for the determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys, with use of a single sample solution. The sample is dissolved in a mixture of hydrobromic acid and bromine, then fumed with sulphuric acid. The lead sulphate is dissolved in concentrated hydrochloric acid. The method is particularly suitable for the determination of silver and bismuth, which are co-precipitated with lead sulphate. The other elements can also be determined after removal of the lead sulphate by filtration.

Matched MeSH terms: Alloys
Fulltext Comparative evaluation of apical bacterial extrusion following root canal instrumentation using different endodontic file systems: An in vitro study

Vankayala B, Anantula K, Saladi H, Gudugunta L, Basavarajaiah JM, Yadav SS

J Conserv Dent, 2020 08 20;22(6):559-563.
PMID: 33088065 DOI: 10.4103/JCD.JCD_221_19

Aim: This study aims to evaluate the amount of apical extrusion of bacteria during root canal instrumentation using K3XF, Protaper Gold, Edge taper platinum, and Hyflex CM Rotary systems.
Materials and Methods: Sixty freshly extracted maxillary incisors teeth collected in saline. Access cavity prepared and canals were made free of bacterial and pulp. The teeth were mounted on the bacteria collecting apparatus. Root canals were contaminated with the Fusobacterium Nucleatum (ATCC25586) and dried at 37°C for 24 h. In Group 1 (Control group): No instrumentation was done and biomechanical preparation done in all other groups with Group 2: Hand K-files, Group 3: Protaper gold, Group 4: K3XF, Group 5: Edge taper platinum, and Group 6: Hyflex CM rotary file systems. Then, the extrude was collected, and it is incubated in Mueller-Hinton agar for 24 h and the number of colony forming units were counted and statistical comparison was done using Kruskal-Wallis test and Mann-Whitney U test.
Results: Hand K-files extruded more bacteria when compared to other four rotary systems, K3XF file system extruded least number of bacteria.
Conclusion: All instrumentation techniques extruded intracanal bacteria apically. However, engine-driven nickel-titanium instruments extruded less bacteria than the manual technique. The K3XF rotary file system comparatively extruded less bacteria than other rotary file systems.

Matched MeSH terms: Alloys
Interfacial Mechanical Strength Enhancement for High-Performance ZnS Thin-Film Anodes

Jiang H, Peng H, Guo H, Zeng Y, Li L, Zhang Y, et al.

ACS Appl Mater Interfaces, 2020 Nov 18;12(46):51344-51356.
PMID: 33146507 DOI: 10.1021/acsami.0c13139

Thin-film lithium-ion microbatteries with a high energy density and long lifespan are exceedingly desired for developing self-powered integrated micro-nano devices and systems. However, exploring high-performance thin-film anodes still remains a challenge. Herein, a double-layer-structure diamond-like carbon-ZnS (DLC-ZnS) thin-film anode fabricated by radio frequency magnetron sputtering exhibits high specific capacity and good cycling stability up to 1000 cycles, superior to the pure ZnS thin-film anode. To understand the mechanism, the bimodal amplitude modulated-frequency modulated atomic force microscopy was used to explore the mechanical properties of the thin films, and the DLC layer shows significantly higher Young's modulus than the ZnS thin film. The DLC interface with a high Young's modulus can effectively buffer the mechanical stress originating from the huge volume changes of the ZnS layer during lithiation/delithiation processes; therefore, the DLC interface maintains the higher mechanical integrity of the DLC-ZnS thin film and improves the utilization of ZnS. In addition, the electrochemical kinetics of the DLC-ZnS and ZnS thin films were also investigated by electrochemical methods. Electrochemical impedance spectroscopy tests indicate the obstacle of the DLC interface to Li+ ion diffusion in the initial charge/discharge processes; however, the DLC-ZnS thin film exhibits lower total resistance than the ZnS thin film afterward. In particular, galvanostatic intermittent titration technique tests were performed to find out the differences between the two thin films during the galvanostatical charge/discharge processes. The results demonstrate the obviously enhanced conversion reaction reversibility and decreased alloy reaction polarization of the DLC-ZnS thin film; therefore, it delivers higher reversible capacity.

Matched MeSH terms: Alloys
Fulltext Levels of Mercury in Fish-Eating Children, With and Without Amalgam Restoration

Padmakumar V, Premkala Raveendran K, Abdulla AM, Ganapathy S, Sainudeen S, Nasim VS, et al.

J Pharm Bioallied Sci, 2019 May;11(Suppl 2):S397-S401.
PMID: 31198376 DOI: 10.4103/JPBS.JPBS_44_19

Background: Mercury is a naturally occurring metal that exists in three forms: elemental (metallic), inorganic, and organic mercury. Amalgam, which is an alloy of inorganic mercury, is used as a restorative material in dentistry. Organic mercury gets ingested in the body mainly by the consumption of seafood. Mercury is also stated to cause various adverse health effects such as gastrointestinal disturbances, dermatitis, muscle weakness, and neurological disorders. In recent years, the use of amalgam has become a controversy stating the various adverse effects of mercury. Hence, the study was conducted to determine and compare the variation in levels of organic and inorganic mercury in fish-eating children before and after placement of amalgam restoration.
Materials and Methods: Seventy-five subjects, 42 males (56%) and 35 females (44%) of age group ranging 7-13 years, living in South Canara district of Karnataka, India, were selected as a part of the study. Hair and urine samples were collected for estimation of organic and inorganic levels of mercury, respectively. Informed consent was collected from all the participating subjects.
Results: On comparison between organic and inorganic mercury levels during the study period, the concentration of organic mercury in hair samples was greater irrespective of amalgam restorations present (1.172 and 0.085, respectively; P < 0.001).
Conclusion: Thus inorganic levels of mercury do not seem to pose a threat as much as the organic levels observed in hair, which remain fairly constant for a longer period of time. Hence in a coastal region where this study was undertaken and fish being a staple food, the risk could probably be attributed to more of an organic toxicity than an inorganic one. Thus amalgam is relatively safe to be practiced and the controversy against it should be reevaluated.

Matched MeSH terms: Alloys
Fulltext Non-Supported Nickel-Based Coral Sponge-Like Porous Magnetic Alloys for Catalytic Production of Syngas and Carbon Bio-Nanofilaments via a Biogas Decomposition Approach

Ali B, Tasirin SM, Aminayi P, Yaakob Z, Ali NT, Noori W

Nanomaterials (Basel), 2018 Dec 14;8(12).
PMID: 30558256 DOI: 10.3390/nano8121053

Porous Ni, Ni-Co, Ni-Fe, and Ni-Cu magnetic alloys with a morphology similar to a giant barrel sponge were synthesized via a facile co-precipitation procedure and then by hydrogen reduction treatment. For the first time, the non-supported alloys with their unique morphology were employed in catalytic biogas decomposition (CBD) at a reaction temperature of 700 °C and 100 mL min-1 to produce syngas and carbon bio-nanofilaments, and the catalysts' behavior, CH₄ and CO₂ conversion, and the carbon produced during the reaction were investigated. All of the equimolar alloy catalysts showed good activity and stability for the catalytic biogas decomposition. The highest sustainability factor (0.66) and carbon yield (424%) were accomplished with the Ni-Co alloy without any significant inactivation for six hours, while the highest carbon efficiency of 36.43 was obtained with the Ni-Co catalyst, which is considered relatively low in comparison with industry standards, indicating a low carbon production process efficiency, possibly due to the relatively high biogas flow rate. The higher activity of the Ni-Co alloy catalyst was associated with the synergistic impact between nickel and cobalt, allowing the catalyst to maintain a high stability throughout the reaction period. Moreover, highly uniform, interwoven carbon bio-nanofilaments with a parallel and fishbone structure were achieved.

Matched MeSH terms: Alloys
Fulltext Effect of Ni on the Suppression of Sn Whisker Formation in Sn-0.7Cu Solder Joint

Hashim AN, Salleh MAAM, Sandu AV, Ramli MM, Yee KC, Mohd Mokhtar NZ, et al.

Materials (Basel), 2021 Feb 05;14(4).
PMID: 33562471 DOI: 10.3390/ma14040738

The evolution of internal compressive stress from the intermetallic compound (IMC) Cu6Sn5 growth is commonly acknowledged as the key inducement initiating the nucleation and growth of tin (Sn) whisker. This study investigates the effect of Sn-0.7Cu-0.05Ni on the nucleation and growth of Sn whisker under continuous mechanical stress induced. The Sn-0.7Cu-0.05Ni solder joint has a noticeable effect of suppression by diminishing the susceptibility of nucleation and growth of Sn whisker. By using a synchrotron micro X-ray fluorescence (µ-XRF) spectroscopy, it was found that a small amount of Ni alters the microstructure of Cu6Sn5 to form a (Cu,Ni)6Sn5 intermetallic layer. The morphology structure of the (Cu,Ni)6Sn5 interfacial intermetallic layer and Sn whisker growth were investigated by scanning electron microscope (SEM) in secondary and backscattered electron imaging mode, which showed that there is a strong correlation between the formation of Sn whisker and the composition of solder alloy. The thickness of the (Cu,Ni)6Sn5 IMC interfacial layer was relatively thinner and more refined, with a continuous fine scallop-shaped IMC interfacial layer, and consequently enhanced a greater incubation period for the nucleation and growth of the Sn whisker. These verification outcomes proposes a scientifically foundation to mitigate Sn whisker growth in lead-free solder joint.

Matched MeSH terms: Alloys
Fulltext The Effect of Welding Current and Electrode Force on the Heat Input, Weld Diameter, and Physical and Mechanical Properties of SS316L/Ti6Al4V Dissimilar Resistance Spot Welding with Aluminum Interlayer

Taufiqurrahman I, Ahmad A, Mustapha M, Lenggo Ginta T, Ady Farizan Haryoko L, Ahmed Shozib I

Materials (Basel), 2021 Feb 27;14(5).
PMID: 33673716 DOI: 10.3390/ma14051129

Welding parameters obviously determine the joint quality during the resistance spot welding process. This study aimed to investigate the effect of welding current and electrode force on the heat input and the physical and mechanical properties of a SS316L and Ti6Al4V joint with an aluminum interlayer. The weld current values used in this study were 11, 12, and 13 kA, while the electrode force values were 3, 4, and 5 kN. Welding time and holding time remained constant at 30 cycles. The study revealed that, as the welding current and electrode force increased, the generated heat input increased significantly. The highest tensile-shear load was recorded at 8.71 kN using 11 kA of weld current and 3 kN of electrode force. The physical properties examined the formation of a brittle fracture and several weld defects on the high current welded joint. The increase in weld current also increased the weld diameter. The microstructure analysis revealed no phase transformation on the SS316L interface; instead, the significant grain growth occurred. The phase transformation has occurred on the Ti6Al4V interface. The intermetallic compound layer was also investigated in detail using the EDX (Energy Dispersive X-Ray) and XRD (X-Ray Diffraction) analyses. It was also found that both stainless steel and titanium alloy have their own fusion zone, which is indicated by the highest microhardness value.

Matched MeSH terms: Alloys
Fulltext Tailoring bismuth borate glasses by incorporating PbO/GeO2 for protection against nuclear radiation

Kumar A, Jain A, Sayyed MI, Laariedh F, Mahmoud KA, Nebhen J, et al.

Sci Rep, 2021 Apr 08;11(1):7784.
PMID: 33833308 DOI: 10.1038/s41598-021-87256-1

Nuclear radiation shielding capabilities for a glass series 20Bi2O3 - xPbO - (80 - 2x)B2O3 - xGeO2 (where x = 5, 10, 20, and 30 mol%) have been investigated using the Phy-X/PSD software and Monte Carlo N-Particle transport code. The mass attenuation coefficients (μm) of selected samples have been estimated through XCOM dependent Phy-X/PSD program and MCNP-5 code in the photon-energy range 0.015-15 MeV. So obtained μm values are used to calculate other γ-ray shielding parameters such as half-value layer (HVL), mean-free-path (MFP), etc. The calculated μm values were found to be 71.20 cm2/g, 76.03 cm2/g, 84.24 cm2/g, and 90.94 cm2/g for four glasses S1 to S4, respectively. The effective atomic number (Zeff)values vary between 69.87 and 17.11 for S1 or 75.66 and 29.11 for S4 over 0.05-15 MeV of photon-energy. Sample S4, which has a larger PbO/GeO2 of 30 mol% in the bismuth-borate glass, possesses the lowest MFP and HVL, providing higher radiation protection efficiency compared to all other combinations. It shows outperformance while compared the calculated parameters (HVL and MFP) with the commercial shielding glasses, different alloys, polymers, standard shielding concretes, and ceramics. Geometric Progression (G-P) was applied for evaluating the energy absorption and exposure buildup factors at energies 0.015-15 MeV with penetration depths up to 40 mfp. The buildup factors showed dependence on the MFP and photon-energy as well. The studied samples' neutron shielding behavior was also evaluated by calculating the fast neutron removal cross-section (ΣR), i.e. found to be 0.139 cm-1 for S1, 0.133 cm-1 for S2, 0.128 cm-1 for S3, and 0.12 cm-1 for S4. The results reveal a great potential for using a glass composite sample S4 in radiation protection applications.

Matched MeSH terms: Alloys
Fulltext A novel and stable way for energy harvesting from Bi2Te3Se alloy based semitransparent photo-thermoelectric module

Fatima N, Karimov KS, Qasuria TA, Ibrahim MA

J Alloys Compd, 2020 Dec 30;849:156702.
PMID: 32834521 DOI: 10.1016/j.jallcom.2020.156702

In this research, due to the present pandemic of COVID-19, we are proposing a stable and fixed semitransparent photo-thermoelectric cell (PTEC) module for green energy harvesting. This module is based on the alloy of Bismuth Telluride Selenide (Bi2Te3Se), designed in a press tablet form and characterized under solar energy. Here, both aspects of solar energy i.e., light and heat are utilized for both energy production and water heating. The semitransparent PTEC converts heat energy directly to electrical energy due to the gradient of temperature between two electrodes (top and bottom) of thermoelectric cells. The PTEC is 25% transparent, which can be varied according to the necessity of the utilizer. The X-ray diffraction of material and electric characterization of module i.e., open-circuited voltage (VOC) and Seebeck coefficient were performed. The experimental observations disclose that in the proposed PTEC module with an increment in the average temperature (TAvg) from 34 to 60 °C, results in the rise of VOC ∼ 2.4 times. However, by modifying the size of heat-absorbing top electrode and by increasing the temperature gradient through the addition of water coolant under the bottom electrode, an uplift in the champion device results in as increment of VOC ∼5.5 times and Seebeck coefficient obtained was -250 μV/0C, respectively. Results show that not only the selection of material but also the external modifications in the device highly effective the power efficiency of the devices. The proposed modules can generate electric power from light and utilize the penetrating sunlight inside the room and for the heating of the water which also acts as a coolant. These semitransparent thermoelectric cells can be built-in within windows and roofs of buildings and can potentially contribute to green energy harvesting, in situations where movement is restricted locally or globally.

Matched MeSH terms: Alloys
Fulltext Determination of Non-Recrystallization Temperature for Niobium Microalloyed Steel

Akhtar MN, Khan M, Khan SA, Afzal A, Subbiah R, Ahmad SN, et al.

Materials (Basel), 2021 May 18;14(10).
PMID: 34070060 DOI: 10.3390/ma14102639

In the present investigation, the non-recrystallization temperature (TNR) of niobium-microalloyed steel is determined to plan rolling schedules for obtaining the desired properties of steel. The value of TNR is based on both alloying elements and deformation parameters. In the literature, TNR equations have been developed and utilized. However, each equation has certain limitations which constrain its applicability. This study was completed using laboratory-grade low-carbon Nb-microalloyed steels designed to meet the API X-70 specification. Nb- microalloyed steel is processed by the melting and casting process, and the composition is found by optical emission spectroscopy (OES). Multiple-hit deformation tests were carried out on a Gleeble® 3500 system in the standard pocket-jaw configuration to determine TNR. Cuboidal specimens (10 (L) × 20 (W) × 20 (T) mm3) were taken for compression test (multiple-hit deformation tests) in gleeble. Microstructure evolutions were carried out by using OM (optical microscopy) and SEM (scanning electron microscopy). The value of TNR determined for 0.1 wt.% niobium bearing microalloyed steel is ~ 951 °C. Nb- microalloyed steel rolled at TNR produce partially recrystallized grain with ferrite nucleation. Hence, to verify the TNR value, a rolling process is applied with the finishing rolling temperature near TNR (~951 °C). The microstructure is also revealed in the pancake shape, which confirms TNR.

Matched MeSH terms: Alloys
Synthesis of Au-Ag Alloy Nanoparticles in Deionized Water by Pulsed Laser Ablation Technique

Norsyuhada W, Shukri WM, Bidin N, Islam S, Krishnan G

J Nanosci Nanotechnol, 2018 Jul 01;18(7):4841-4851.
PMID: 29442664 DOI: 10.1166/jnn.2018.15358

Au-Ag alloy nanoparticles are physically synthesized using rapid, simple and efficient Q-switched Nd:YAG pulsed laser ablation in liquid technique (PLAL). Au and Ag colloidal solutions are separately prepared by 1064 nm laser ablation of metallic target (gold and silver) which is immersed in deionized water. Au-Ag alloy nanoparticles are prepared by irradiating the mixture of Au and Ag colloidal solutions with 532 nm of second harmonic wavelength of Nd:YAG laser at three different ratio, 3:1, 1:1 and 1:3 within different exposure times. The three of plasmon absorption bands of Au-Ag nanoparticles are shifted linearly to the lower wavelength [499.67 nm (3:1), 481.25 nm (1:1), 467.91 nm (1:3)], as compared to plasmon absorption spectra of pure Au (520 nm) and Ag (400 nm). Moreover, the change in colors are also observed from red (Au) and yellow (Ag) to orange, brown and green color due to the Au-Ag alloy formations, respectively. Transmission electron microscopy shows the Ag shell around the inner core of Au spherical metal with broad size distribution due to the three different volume ratio, respectively (1.7 nm, 0.7 nm, 1.4 nm). Energy-dispersive X-ray spectroscopy analysis confirms the presence of Au and Ag elements in Au-Ag alloy nanoparticles without any contaminations. Attenuated total reflectance fourier transform infrared spectroscopy analysis also confirms the homogenous Au-Ag alloys chemical bonding.

Matched MeSH terms: Alloys
Fulltext Occupational lead exposure of soldering workers in an electronic factory

Mimala Arasaratnam, Zailina Hashim, Shamsul Bahari Shamsudin

Journal of Occupational Safety and Health, 2004;1(2):39-55.
MyJurnal

A cross-sectional study was conducted on 83 female electronics factory workers. The respondents comprised 50 exposed workers who use lead alloy solder and 33 unexposed workers. The objective of this study was to assess the lead exposure of these workers. Breathing zone were sampled using air sampling pumps. Dust samples were collected by wipe method. Venous blood collected and blood pressure were measured. All lead analyses were carried out with Graphite Furnace Atomic Absorption Spectrophotometer. The mean air lead for exposed workers (57 0. ± 0.93 μg/m³) was significantly higher than the unexposed workers (0.0067 ± 0.0045μg/m³) (p

Matched MeSH terms: Alloys

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