Verification of the Stokes-Einstein relation in liquid noble metals over a wide range of temperatures

2021 ◽  
pp. 127385
Author(s):  
Most. Nayema Khatun ◽  
R.C. Gosh
Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4672
Author(s):  
Mohamed H. Hassan ◽  
Cian Vyas ◽  
Bruce Grieve ◽  
Paulo Bartolo

The detection of glucose is crucial in the management of diabetes and other medical conditions but also crucial in a wide range of industries such as food and beverages. The development of glucose sensors in the past century has allowed diabetic patients to effectively manage their disease and has saved lives. First-generation glucose sensors have considerable limitations in sensitivity and selectivity which has spurred the development of more advanced approaches for both the medical and industrial sectors. The wide range of application areas has resulted in a range of materials and fabrication techniques to produce novel glucose sensors that have higher sensitivity and selectivity, lower cost, and are simpler to use. A major focus has been on the development of enzymatic electrochemical sensors, typically using glucose oxidase. However, non-enzymatic approaches using direct electrochemistry of glucose on noble metals are now a viable approach in glucose biosensor design. This review discusses the mechanisms of electrochemical glucose sensing with a focus on the different generations of enzymatic-based sensors, their recent advances, and provides an overview of the next generation of non-enzymatic sensors. Advancements in manufacturing techniques and materials are key in propelling the field of glucose sensing, however, significant limitations remain which are highlighted in this review and requires addressing to obtain a more stable, sensitive, selective, cost efficient, and real-time glucose sensor.


Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 894 ◽  
Author(s):  
Alexander Mitropoulos ◽  
F. Burpo ◽  
Chi Nguyen ◽  
Enoch Nagelli ◽  
Madeline Ryu ◽  
...  

Nobel metal composite aerogel fibers made from flexible and porous biopolymers offer a wide range of applications, such as in catalysis and sensing, by functionalizing the nanostructure. However, producing these composite aerogels in a defined shape is challenging for many protein-based biopolymers, especially ones that are not fibrous proteins. Here, we present the synthesis of silk fibroin composite aerogel fibers up to 2 cm in length and a diameter of ~300 μm decorated with noble metal nanoparticles. Lyophilized silk fibroin dissolved in hexafluoro-2-propanol (HFIP) was cast in silicon tubes and physically crosslinked with ethanol to produce porous silk gels. Composite silk aerogel fibers with noble metals were created by equilibrating the gels in noble metal salt solutions reduced with sodium borohydride, followed by supercritical drying. These porous aerogel fibers provide a platform for incorporating noble metals into silk fibroin materials, while also providing a new method to produce porous silk fibers. Noble metal silk aerogel fibers can be used for biological sensing and energy storage applications.


Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 997
Author(s):  
Nicolas Vogt ◽  
Vasily Sivchik ◽  
Aaron Sandleben ◽  
Gerald Hörner ◽  
Axel Klein

The organonickel complexes [Ni(Phbpy)X] (X = Br, OAc, CN) were obtained for the first time in a direct base-assisted arene C(sp2)–H cyclometalation reaction from the rather unreactive precursor materials NiX2 and HPhbpy (6-phenyl-2,2′-bipyridine) or from the versatile precursor [Ni(HPhbpy)Br2]2. Different from previously necessary C‒Br oxidative addition at Ni(0), an extended scan of reaction conditions allowed quantitative access to the title compound from Ni(II) on synthetically useful timescales through base-assisted C‒H activation in nonpolar media at elevated temperature. Optimisation of the reaction conditions (various bases, solvents, methods) identified 1:2 mixtures of acetate and carbonate as unrivalled synergetic base pairs in the optimum protocol that holds promise as a readily usable and easily tuneable access to a wide range of direct nickelation products. While for the base-assisted C‒H metalation of the noble metals Ru, Ir, Rh, or Pd, this acetate/carbonate method has been established for a few years, our study represents the leap into the world of the base metals of the 3d series.


Author(s):  
Bankim B. Ghosh ◽  
Prokash Chandra Roy ◽  
Mita Ghosh ◽  
Paritosh Bhattacharya ◽  
Rajsekhar Panua ◽  
...  

Three Way Catalysts (TWC) are extensively used for simultaneous control of three principal automotive pollutants, namely carbon monoxide (CO), Oxides of nitrogen (NOx), and hydrocarbon (HC). Most of works on three way catalytic converter have been carried out with noble metals such as Platinum, Rhodium, and Iridium have been tried individually and in different combinations and proportions. Noble metal catalysts give very good performance of reduction of (NOx), CO and HC in the narrow range of stoichiometric Air Fuel ratio. Noble metals are costly and not abundantly available. These draw backs of the noble metal catalysts have inspired to search for the alternative catalysts, which will perform well over the wide range of A/F ratio and are economical and abundantly available. This paper discusses the processing of ZSM-5 to Cu-Ion- Exchanged ZSM-5, ZSM-5 supported Cu-Pt bimetallic catalyst and Cu-Rh bimetallic catalyst and placing them in a three staged converter to study the reduction efficiencies of exhaust emissions CO, NOx, and HC in a 800 cc Maruti S. I. Engine. The experiments are carried out at 1500 rpm, 17.6 A/F ratio, different catalyst bed temperatures and different engine loads 0%, 17.5%, 35%, 52.5%, and 70% of full load. The results achieved are the maximum reduction of CO 90% at 375 °C NOx 90% at 375 °C and HC 61% at 380 °C. The same engine was also run for Noble metal converter (NMC) (EURO-II) purchased from an authorized Maruti distributor and the maximum reduction achieved were CO 89% at 375° C, NOx 91% at 375° C, and HC 70% at 390° C comparable to Zeolite Catalytic Converter (ZCC).


2020 ◽  
pp. 28-32
Author(s):  
N. P. Khrunina ◽  

Characteristics of the placers with increased clayiness of gold-bearing bed and high content of fine and thin gold of the Far Eastern region, as well as technological approaches to processing, including the main process – disintegration, are analyzed. It is established that a reagentless gravitational working up based on generation of acoustic vibrations in fluid media is promising and requires its development. Energy-dispersive microanalysis by means of a scanning electron microscope, phase analysis using a diffractometer, as well as granulometric, dispersed and acoustic analyses have been applied to clay conglomerates selected at a high-clayey section of the deposit under consideration on the Malaya Nesterovka River in Primorskyi Krai. The presence of a wide range of noble metals, including gold and silver, rare earth and other elements was revealed. The data obtained on the composition and properties of clay conglomerates made it possible to determine the need for a more intensive process of the sand micro-disintegration to extract fine and thin particles of valuable components based on expanding the use of gravity technologies. It is noted that the known technologies would not ensure effective extraction of valuable components. A gravitational technology with cavitation reactors, which provide a power inputs reduction by several times in comparison with known devices, is proposed and validated. The hydrodynamic generator design is developed based on the concept of the fluid flow kinetic energy converting into the energy of hydroacoustic vibrations and jet streams of mineral hydromixtures in constrained conditions taking into account the similarity theory in modeling the cavitation processes. The proposed technology will reduce in-process losses of precious and other valuable metals, increase profitability and environmental safety in comparison with known processes.


2014 ◽  
Vol 2014 ◽  
pp. 1-28 ◽  
Author(s):  
Arash Dehghan Banadaki ◽  
Amir Kajbafvala

Nobel metal nanomaterials with interesting physical and chemical properties are ideal building blocks for engineering and tailoring nanoscale structures for specific technological applications. Bimetallic nanomaterials consisting of magnetic metals and noble metals have attracted much interest for their promising potentials in many fields including magnetic sensors, catalysts, optical detection, and biomedical applications. Particularly, effective control of the size, shape, architecture, and compositional microstructure of metal nanomaterials plays an important role in enhancing their functionality and application potentials, for example, in fuel cells, optical and biomedical sensing. This paper focuses on recent advances in controllable synthesis of bimetallic nanostructured materials. Recent contributions in controllable synthesis of bimetallic nanomaterials with different architectures including nanoparticles, nanowires, nanosheets, or nanotubes and their assemblies are presented in this paper. A wide range of facile synthesis methods are covered herein with high emphasis on wet chemical methods owing to their facility of use, efficacy, and smaller environmental footprint.


2014 ◽  
Vol 17 (1) ◽  
pp. 17 ◽  
Author(s):  
G.G. Xanthopouloua ◽  
V.A. Novikova ◽  
Yu.A. Knysha ◽  
A.P. Amosova

<p>The oxidation of CO covers a wide range of applications from gas masks, gas sensors, indoor air quality control to hydrogen purification for polymer electrolyte fuel cells. The reaction attracts renewed interest both in fundamental and applied research of catalysis and electrochemistry. Recent developments and trends in catalysis towards the synthesis of nanocatalysts for CO oxidation are discussed in this review. Different modifications made to conventional catalysts synthesis approaches for preparation of nanocatalysts are critically analyzed. Nanocatalysts developed on the basis of noble metals completely convert CO at temperatures below 0 °C. The development of active and stable catalysts without noble metals for low-temperature CO oxidation is a significant challenge. It was found that Co<sub>3</sub>O<sub>4</sub> nanorods can be steadily active for CO oxidation at a temperature as low as –77 °C. High activity of catalysts at low temperatures connected with nanosize particles and high surface area. This review summarized main directions of nanocatalysts development for CO low temperature oxidation.</p>


Author(s):  
D.N. Dunn ◽  
P. Xu ◽  
L.D. Marks

The growth of noble metals such as Au and Ag on Si and Ge is of considerable interest for modern semi-conductor device applications. Several groups have investigated the room temperature growth of Au films on Ge (111) substrates using RHEED, LEED, UPS, as well as other techniques. It is clear from these investigations that the growth of Au on Ge (111) proceeds by a mechanism contrary to what might be expected by comparison to the growth of Au on Si (111). In general most of these studies have looked in two regimes, the first being simple room temperature growth over a wide range of Au coverages from a few tenths of a monolayer up to 100 Å in thickness. The second regime is the behavior of these Au films as a function of annealing temperature. Using RHEED and LEED to study a wide range of Au coverages, Le Lay and coworkers have found that the growth mechanism of Au films proceeds by the appearance of two dimensional close packed domains which do not completely cover the surface.


2000 ◽  
Vol 14 (21) ◽  
pp. 2231-2240 ◽  
Author(s):  
S. FUJITA ◽  
H.-C. HO ◽  
Y. OKAMURA

Based on the idea that different temperatures generate different carrier densities and the resulting diffusion causes the thermal emf, a new formula for the Seebeck coefficient S is obtained: [Formula: see text], where q, n, εF, [Formula: see text]. and [Formula: see text]. are respectively charge, carrier density, Fermi energy, density of states at ∊F and volume. Ohmic and Seebeck currents are fundamentally different in nature. This difference can cause significantly different transport behaviors. For a multi-carrier metal the Einstein relation between the conductivity and the diffusion coefficient does not hold in general. Seebeck (S) and Hall (RH) coefficients in noble metals have opposite signs. This is shown to arise from the Fermi surface having "necks" at the Brillouin boundary.


2019 ◽  
Vol 96 (1) ◽  
Author(s):  
Frank Reith ◽  
Donna M Falconer ◽  
Joy Van Nostrand ◽  
David Craw ◽  
Jeremiah Shuster ◽  
...  

ABSTRACT Gold particles contain gold and other toxic, heavy metals, making them ‘extreme’ geochemical microenvironments. To date, the functional capabilities of bacterial biofilms to deal with these conditions have been inferred from taxonomic analyses. The aims of this study are to evaluate the functional capabilities of bacterial communities on gold particles from six key locations using GeoChip 5.0 and to link functional and taxonomic data. Biofilm communities displayed a wide range of functional capabilities, with up to 53 505 gene probes detected. The capability of bacterial communities to (re)cycle carbon, nitrogen, and sulphur were detected. The cycling of major nutrients is important for maintaining the biofilm community as well as enabling the biogeochemical cycling and mobilisation of heavy and noble metals. Additionally, a multitude of stress- and heavy metal resistance capabilities were also detected, most notably from the α/β/γ-Proteobacteria and Actinobacteria. The multi-copper-oxidase gene copA, which is directly involved in gold resistance and biomineralisation, was the 15th most intense response and was detected in 246 genera. The Parker Road and Belle Brooke sites were consistently the most different from other sites, which may be a result of local physicochemical conditions (extreme nutrient poverty and sulphur-richness, respectively). In conclusion, biofilms on gold particles display wide-ranging metabolic and stress-related capabilities, which may enable them to survive in these niche environments and drive biotransformation of gold particles.


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