A double SAW resonator system was developed as a novel method for gas sensing applications. The proposed system was investigated for hydrogen sensing. Commercial Surface Acoustic Wave (SAW) resonators with resonance frequencies of 433.92 MHz and 433.42 MHz were employed in the double SAW resonator system configuration. The advantages of using this configuration include its ability for remote measurements, and insensitivity to vibrations and other external disturbances. The sensitive layer is composed of functionalized multiwalled carbon nanotubes and polyaniline nanofibers which were deposited on pre-patterned platinum metal electrodes fabricated on a piezoelectric substrate. This was mounted into the DSAWR circuit and connected in parallel. The sensor response was measured as the difference between the resonance frequencies of the SAW resonators, which is a measure of the gas concentration. The sensor showed good response towards hydrogen with a minimum detection limit of 1%.
A gas sensor array was developed in a 10 × 10 mm(2) space using Screen Printing and Pulse Laser Ablation Deposition (PLAD) techniques. Heater, electrode, and an insulator interlayer were printed using the screen printing method on an alumina substrate, while tin oxide and platinum films, as sensing and catalyst layers, were deposited on the electrode at room temperature using the PLAD method, respectively. To ablate SnO(2) and Pt targets, depositions were achieved by using a 1,064 nm Nd-YAG laser, with a power of 0.7 J/s, at different deposition times of 2, 5 and 10 min, in an atmosphere containing 0.04 mbar (4 kPa) of O(2). A range of spectroscopic diffraction and real space imaging techniques, SEM, EDX, XRD, and AFM were used in order to characterize the surface morphology, structure, and composition of the films. Measurement on the array shows sensitivity to some solvent and wood smoke can be achieved with short response and recovery times.
This paper reports a rapid and in-situ electrochemical polymerization method for the fabrication of polypyrrole nanoparticles incorporated reduced graphene oxide (rGO@PPy) nanocomposites on a ITO conducting glass and its application as a counter electrode for platinum-free dye-sensitized solar cell (DSSC). The scanning electron microscopic images show the uniform distribution of PPy nanoparticles with diameter ranges between 20 and 30 nm on the rGO sheets. The electrochemical studies reveal that the rGO@PPy has smaller charge transfer resistance and similar electrocatalytic activity as that of the standard Pt counter electrode for the I₃(-)/I(-) redox reaction. The overall solar to electrical energy conversion efficiency of the DSSC with the rGO@PPy counter electrode is 2.21%, which is merely equal to the efficiency of DSSC with sputtered Pt counter electrode (2.19%). The excellent photovoltaic performance, rapid and simple fabrication method and low-cost of the rGO@PPy can be potentially exploited as a alternative counter electrode to the expensive Pt in DSSCs.
Copper zinc tin sulfide (CZTS) is a promising material for harvesting solar energy due to its abundance and non-toxicity. However, its poor performance hinders their wide application. In this paper gold (Au) nanoparticles are successfully incorporated into CZTS to form Au@CZTS core-shell nanostructures. The photocathode of Au@CZTS nanostructures exhibits enhanced optical absorption characteristics and improved incident photon-to-current efficiency (IPCE) performance. It is demonstrated that using this photocathode there is a significant increase of the power conversion efficiency (PCE) of a photoelectrochemical solar cell of 100% compared to using a CZTS without Au core. More importantly, the PCE of Au@CZTS photocathode improved by 15.8% compared to standard platinum (Pt) counter electrode. The increased efficiency is attributed to plasmon resonance energy transfer (PRET) between the Au nanoparticle core and the CZTS shell at wavelengths shorter than the localized surface plasmon resonance (LSPR) peak of the Au and the semiconductor bandgap.
Type of bond is vital to understand the mechanism of interaction between corresponds atoms. We used three kinds of method
to determine the type of bond between diatomic cluster of platinum and hydrogen: types of element, electronegativity
and electron distribution. In this work, we found that the results from these three methods are not unanimously agreed
with each other for bond type forming in platinum-hydrogen diatomic cluster. Thus, we conclude that the type of bond
is hybrid of both: mainly covalent and slightly ionic.
Reduced graphene oxide nanosheet (RGO)/Pt nanocomposite have been successfully prepared through a facile chemical reduction method. The reduction of Pt precursor was carried out using sodium borohydride as the efficient chemical reductant. The morphology of RGO/Pt nanocomposite was investigated using high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). HRTEM analysis showed that platinum nanoparticles were homogenously distributed onto the surface of RGO. The electrochemical study proved that Pt nanoparticles were successfully incorporated onto RGO. Therefore, it can be concluded that the proposed method could provide well-dispersed of Pt nanoparticles onto RGO to form RGO/ Pt nanocomposite.
HOMO and LUMO of organic compounds are basic parameters for the design and fabrication of an organic solar cell. This paper presents a technique to obtain HOMO and LUMO of an n-type polymer of [6,6]-phenyl C61-butyric acid 3-ethylthiophene ester (PCBE) and a p-type polymer of poly (3-octyl-thiophene-2, 5-diyl) (P3OT). The energy of band gap for each material has been calculated using optical absorption spectrum. Cyclic Voltammetry was used to estimate the oxidation potential and energy band diagram consequently. The experiments were carried out in a three-electrode cell consisting of a platinum working electrode, a platinum counter electrode and a SCE reference electrode. P3OT showed energy band gap equal to 1.83 eV with HOMO and LUMO equal to 5.59 eV and 3.76 eV, respectively. PCBE showed energy band gap equal to 1.96 eV with HOMO and LUMO equal to 5.87 eV and 3.91 eV, respectively. Based on energy band diagram that was constructed from this experimental result, the couple materials may be successfully used to fabricate the feasible organic solar cells.
Rhodinol is a mixture of geraniol and citronellol. It is the second fraction in fractional distillation of commercially grown Cymbopogon nardus. The physical and chemical similarities of these two compounds made them inseparable. The individual use of each compound is of great importance. A selective oxidation (hydrogen peroxide activated by platinum black) of geraniol (in rhodinol) to geranial was done while remaining citronellol intact in order to separate the two compounds into different chemical functionality. A yield of 81% geranial achieved while minimizing citronellal formation from citronellol to 17%. Chemical separation using sodium hydrogen sulfite (NaHSO3) was done to separate the aldehydes from the unreacted citronellol. Purification using fractional distillation was done to obtain pure geraniol and remove minor fraction of citronellal.
Elektrod platinum-polivinilklorida (Pt-PVC) untuk pengoksidaan elektrokimia etanol dalam larutan alkali telah direkabentuk. Elektrod Pt-PVC dibina dengan mencampurkan serbuk-serbuk logam platinum dengan PVC (95:5 w/w), diaduk untuk mendapatkan campuran yang homogen, ditambahkan dengan tetrahidrofuran (THF) untuk melarutkan PVC, dikeringkan, dimasukkan ke dalam acuan berdiameter 1 cm dan ditekan pada tekanan kira-kira 10 tan/cm2. Kajian elektrokimia dilakukan menggunakan voltammetri kitaran (CV) dan kronokoulometri (CC). CV untuk etanol yang menggunakan elektrod-elektrod kepingan logam Pt dan Pt-PVC masing-masing memberikan ketumpatan arus 0.25 mA/cm2 dan 85 mA/cm2 untuk puncak penjerapan hidroksida. Ini menunjukkan bahawa elektrod Pt-PVC mempunyai nilai konduktiviti dan perilaku elektrokimia yang lebih baik untuk pengoksidaan etanol dalam KOH berbanding elektrod kepingan logam Pt. Hasil kajian mendapati bahawa terdapat peningkatan peratus hasil elektrolisis dari 3.64% kepada 23.64% asid asetik apabila elektrod Pt-PVC digunakan untuk pengoksidaan elektrokimia 0.25 M etanol dalam larutan elektrolit 1.0 M KOH menggantikan elektrod kepingan logam Pt.
The formation of nano pores on aluminum at 30oC- 38oC, employing a one step anodization technique which does not require removing the oxide layer formed is presented. A 20% phosphoric acid electrolyte (concentration higher than the normal anodization concentration of 5 to 10%) at a cell potential of 60 volts was used. A platinum electrode was used as the cathode electrode while the aluminum substrate as the anode electrode. A dc powered electrochemical cell to provide the required amount of current density (without the use of temperature controlled water bath) suitable or necessary for pore formation at room temperature was employed. The results obtained show that pore formation at room temperature is achievable and the pore diameter ranged between 80-120 nm.
The effects of the annealing temperatures and thicknesses on the shapes, sizes and arrangement of platinum (Pt) nanoparticles (NPs) on graphene and their sensing performance for hydrogen (H2) detection were investigated. It shows strong dependency of the annealing temperatures and thicknesses on the properties of NPs. It was found that the proposed technique is able to form the NPs with good size controllability and uniformity even for thick deposited layer, thus eliminating the requirement of very thin layer of below 5 nm for the direct NP synthesis by evaporation or sputtering. The transport properties of Pt NPs/graphene structure and its sensing performance on H2 at room temperature under various H2 concentration were evaluated. The results showed an acceptable sensing response, indicating an innovative approach to fabricate Pt NPs embedded graphene for gas sensing application.
The process of etching is the most crucial part of the work of manufacturing printed circuit boards (PCB). In the etching process by nitric acid, a spent etching waste solution of composition 250 g/L HNO3, 30-40 g/L Cu, 30-40 g/L Sn, 30-40 g/L Pb and 20-25 g/L Fe is produced. High metal concentrations in the spent etching waste solution make it a viable candidate for the recovery of metals. Recovery of metals from spent etching waste solution is a significant concern as the recent growth in production of printed circuit boards has generated a drastic increase of spent etching waste solution each year. This study concerns itself with the recovery of metals from spent etching waste. In this study a dilution was made in order to increase the pH of the solution as spent etching waste solution has high acidity, and the electrowinning method was performed to recover metals from the spent etching waste solution. Glassy carbon and platinum were used as cathode and anode in order to investigate the electrodeposition of metals and cyclic voltammetry investigation suggests that the deposition of metals on glassy carbon electrodes occurs at four different overpotentials mainly at -0.15 V, -0.35 V, -0.45 V and -0.75 V. Microscopy observation demonstrates that there is a deposition of metals by applying the potentials in a set of current-time transient study for a duration of 60 seconds and the metals recovered formed as aggregates.
Background. Diurnal rhythms of protein synthesis controlled by the biological clock underlie the rhythmic physiology in the fruit fly, Drosophila melanogaster. In this study, we conducted a proteome-wide investigation of rhythmic protein accumulation in D. melanogaster. Materials and Methods. Total protein collected from fly samples harvested at 4 h intervals over the 24 h period were subjected to two-dimensional gel electrophoresis, trypsin digestion and MS/MS analysis. Protein spots/clusters were identified with MASCOT search engine and Swiss-Prot database. Expression of proteins was documented as percentage of volume contribution using the Image Master 2D Platinum software. Results. A total of 124 protein spots/clusters were identified using MS/MS analysis. Significant variation in the expression of 88 proteins over the 24-h period was observed. A relatively higher number of proteins was upregulated during the night compared to the daytime. The complexity of temporal regulation of the D. melanogaster proteome was further reflected from functional annotations of the differently expressed proteins, with those that were upregulated at night being restricted to the heat shock proteins and proteins involved in metabolism, muscle activity, protein synthesis/folding/degradation and apoptosis, whilst those that were overexpressed in the daytime were apparently involved in metabolism, muscle activity, ion-channel/cellular transport, protein synthesis/folding/degradation, redox homeostasis, development and transcription. Conclusion. Our data suggests that a wide range of proteins synthesized by the fruit fly, D. melanogaster, is under the regulation of the biological clock.
Metal nanoparticles prepared by exsolution at the surface of perovskite oxides have been recently shown to enable new dimensions in catalysis and energy conversion and storage technologies owing to their socketed, well-anchored structure. Here we show that contrary to general belief, exsolved particles do not necessarily re-dissolve back into the underlying perovskite upon oxidation. Instead, they may remain pinned to their initial locations, allowing one to subject them to further chemical transformations to alter their composition, structure and functionality dramatically, while preserving their initial spatial arrangement. We refer to this concept as chemistry at a point and illustrate it by tracking individual nanoparticles throughout various chemical transformations. We demonstrate its remarkable practical utility by preparing a nanostructured earth abundant metal catalyst which rivals platinum on a weight basis over hundreds of hours of operation. Our concept enables the design of compositionally diverse confined oxide particles with superior stability and catalytic reactivity.
Due to its built-up chemoresistance after prolonged usage, the demand for replacing platinum in metal-based drugs (MBD) is rising. The first MBD approved by the FDA for cancer therapy was cisplatin in 1978. Even after nearly four and a half decades of trials, there has been no significant improvement in osteosarcoma (OS) therapy. In fact, many MBD have been developed, but the chemoresistance problem raised by platinum remains unresolved. This motivates us to elucidate the possibilities of the copper and zinc (CuZn) combination to replace platinum in MBD. Thus, the anti-chemoresistance properties of CuZn and their physiological functions for OS therapy are highlighted. Herein, we summarise their chelators, main organic solvents, and ligand functions in their structures that are involved in anti-chemoresistance properties. Through this review, it is rational to discuss their ligands' roles as biosensors in drug delivery systems. Hereafter, an in-depth understanding of their redox and photoactive function relationships is provided. The disadvantage is that the other functions of biosensors cannot be elaborated on here. As a result, this review is being developed, which is expected to intensify OS drugs with higher cure rates. Nonetheless, this advancement intends to solve the major chemoresistance obstacle towards clinical efficacy.
Platinum-based chemotherapy (PBC) is a widely used treatment for various solid tumors, including non-small cell lung cancer (NSCLC). However, its efficacy is often compromised by the emergence of drug resistance in patients. There is growing evidence that genetic variations may influence the susceptibility of NSCLC patients to develop resistance to PBC. Here, we provide a comprehensive overview of the mechanisms underlying platinum drug resistance and highlight the important role that genetic polymorphisms play in this process. This paper discussed the genetic variants that regulate DNA repair, cellular movement, drug transport, metabolic processing, and immune response, with a focus on their effects on response to PBC. The potential applications of these genetic polymorphisms as predictive indicators in clinical practice are explored, as are the challenges associated with their implementation.
The study presents the synthesis of polypyrrole-coated palladium platinum/nitrogen-doped reduced graphene oxide nanocomposites (PdPt-PPy/N-rGO NC) via direct the reduction of Pd(II) and Pt(II) in the presence of pyrrole monomer, N-rGO and L-cysteine as the reducing agent. X-ray diffraction confirmed the presence of metallic Pd and Pt from the reduction of Pd and Pt cations. Transmission electron microscopy images revealed the presence of Pd, Pt and PPy deposition on N-rGO. Impedance spectroscopy results gave a decreased charge transfer resistance due to the presence of N-rGO. The nanocomposites were synthesized with different Pd/Pt ratios (2:1, 1:1 and 1:2). A glassy carbon electrode (GCE) modified with the nanocomposite showed enhanced electrochemical sensing capability for formaldehyde in 0.1 M sulfuric acid solution. Cyclic voltammetry showed an increase in the formaldehyde oxidation peak current at the GCE modified with Pd2Pt1 PPy N-rGO. At a typical potential of 0.45 V (vs. SCE), the sensitivity in the linear segment was 345.8 μA.mM -1. cm-2. The voltammetric response was linear between 0.01 and 0.9 mM formaldehyde concentration range, with a 27 µM detection limit (at S/N = 3). Graphical abstract Schematic presentation of formaldehyde detection by Pd2Pt1-PPy/nitrogen-doped reduced Graphene Oxide Nanocomposite (Pd2Pt1-PPy /N-Gr NC). The decrease of charge transfer resistance and the agglomeration of deposited metals in the presence of N-rGO enhance the current response of the electrochemical sensor.
WO₃-decorated TiO₂ nanotube arrays were successfully synthesized using an in situ anodization method in ethylene glycol electrolyte with dissolved H₂O₂ and ammonium fluoride in amounts ranging from 0 to 0.5 wt %. Anodization was carried out at a voltage of 40 V for a duration of 60 min. By using the less stable tungsten as the cathode material instead of the conventionally used platinum electrode, tungsten will form dissolved ions (W(6+)) in the electrolyte which will then move toward the titanium foil and form a coherent deposit on the titanium foil. The fluoride ion content was controlled to determine the optimum chemical dissolution rate of TiO₂ during anodization to produce a uniform nanotubular structure of TiO₂ film. Nanotube arrays were then characterized using FESEM, EDAX, XRD, as well as Raman spectroscopy. Based on the FESEM images obtained, nanotube arrays with an average pore diameter of up to 65 nm and a length of 1.8 µm were produced. The tungsten element in the samples was confirmed by EDAX results which showed varying tungsten content from 0.22 to 2.30 at%. XRD and Raman results showed the anatase phase of TiO₂ after calcination at 400 °C for 4 h in air atmosphere. The mercury removal efficiency of the nanotube arrays was investigated by photoirradiating samples dipped in mercury chloride solution with TUV (Tube ultraviolet) 96W UV-B Germicidal light. The nanotubes with the highest aspect ratio (15.9) and geometric surface area factor (92.0) exhibited the best mercury removal performance due to a larger active surface area, which enables more Hg(2+) to adsorb onto the catalyst surface to undergo reduction to Hg⁰. The incorporation of WO₃ species onto TiO₂ nanotubes also improved the mercury removal performance due to improved charge separation and decreased charge carrier recombination because of the charge transfer from the conduction band of TiO₂ to the conduction band of WO₃.
Saccular aneurysms associated with moyamoya disease are commonly located in the vertebrobasilar circulation. Anterior circulation aneurysm associated with moyamoya disease is uncommon and is usually treated by neurosurgical clipping. Objective: We report a succesful treatment using the endovascular approach in a case of ruptured anterior communicating artery aneurysm in unilateral moyamoya disease. Clinical Presentation: A 23 year old man presented with a 5 day history of headache, diplopia and fever. Computed Tomography (CT) scan and cerebral angiogram showed a bilobed anterior comunicating artery aneurysm. There was also severe M1 segment stenosis of the left middle cerebral artery with multiple collaterals, representing moyamoya vessels. Intervention: Treatment was done under general anesthesia and followed the standard practice for endovascular treatment. The aneurysm was occluded with three detachable platinum microcoils (Microplex®, Microvention®). Conclusion: Endovascular treatment can be a treatment option for ruptured anterior circulation saccular aneurysms associated with moyamoya disease.
The substrate effects on surface morphologies, crystal structures, and magnetic properties of the sputter-deposited FePt thin films on Corning 1737, normal glass, and Si wafer substrates, respectively, were investigated. High in-plane coercivities of 10 kOe were obtained for the air-annealed films on Corning 1737 and Si wafer, where both films similarly have granular-like morphologies. Besides, increasing grain size and surface roughness of all the FePt films with the post-anneal temperature were observed. Moreover, partially separated grains were seen in the film on Si wafer, where the formation of Fe silicides during post-anneal is suspected, in which has enhanced the magnetic ordering.