Silicon Compounds Research Articles

Modelling the extraction process parameters of amorphous silica-rich rice husk ash using hybrid RSM−BPANN−MOGA optimization technique

This study was aimed to optimize process conditions for recovery of amorphous silica-rich rice husk ash (RHA) as a highly reactive precursor of silicon compounds for valorization of a non-conventional agricultural waste rice husk. The optimization was accomplished using a hybrid multi-objective genetic algorithm (MOGA) coupled with back-propagation artificial neural networks (BPANN) and response surface methodology (RSM). Herein, process conditions, namely leaching temperature (65–85 °C) & time (0.5–1.5 h) and calcination temperature (450–650 °C) & time (1−3 h) were considered as independent variables. The influence of process parameters on % crystallinity and volume % of silica in RHA were studied based on X-ray diffraction analysis and RHA recovery. In the hybrid RSM−BPANN−MOGA model, predicted data of BPANN were used as initial score and regression equations of RSM were used for development of fitness function. A set of optimal solutions were obtained as Pareto front and the final optimum design point was selected using TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) decision-making tool. The optimized process conditions were: leaching temperature: 75 °C, leaching time: 1 h, calcination temperature: 550 °C, and calcination time: 2 h. The optimized model was validated with observed results and found to be a well-fitted with absolute errors of 7.42%, 2.03%, and 4.26% for % crystallinity, RHA recovery, and vol% of silica, respectively. Further, a comparative study was performed between non-leached RHA and optimized RHA using several material characterization techniques. This study showed relative superiority of optimized treatment parameters with increased purity and decreased crystallinity and porous particle morphology.

Recent Advances in the Nanomaterials, Design, Fabrication Approaches of Thermoelectric Nanogenerators for Various Applications

AbstractThermoelectric nanogenerators (TENGs) are promising sustainable energy devices that utilize thermoelectric (TE) effect of nanomaterials to convert a temperature gradient into electrical energy. Compared to bulk thermoelectric generators (TEGs) that are commercially available, TENGs are more flexible and power‐dense, owing to their tuneable nanostructures. Hence, smaller TENGs are better suited for small form‐factor applications like wearable electronics, internet of things (IoT) devices, and self‐powered sensors. However, the higher complexity and cost of TENGs than TEGs inhibit their widespread adoption. This review appraises the latest advances in TENG materials, design, and fabrication in optimizing the performance of TENGs, making TENGs more viable for real‐world applications. More precisely, this work examines how nanostructure engineering, nanomaterial compositing, and post‐synthesis treatment approaches have enhanced the TE properties of common and promising TE materials, including tellurides, selenides, metal oxides, metal alloys, silicon, carbon nanomaterials, and organic compounds. Given that the TE material is a key component in TENGs, this review highlights how to optimize other vital parameters, including the TENG configuration, contact interface, form factor, heat sink use, and folded shape for specific applications. Lastly, critical attributes of TENGs used in wearable electronics, sensors, implantable electronics, solar energy conversion, and waste heat recovery are analyzed.

Stimuli Responsive Silylene: Electromerism Induced Reversible Switching Between Mono- and Bis-Silylene.

Electromerism is a very well-known phenomenon in transition metal chemistry. In main group chemistry, this concept has only started getting attention recently. We report stimuli responsive low-valent silicon compounds exhibiting electromerism. A mixed-valent silaiminyl-silylene 1, [LSi-Si(NDipp)L] (L=PhC(Nt Bu)2 ), was synthesized in a single step from amidinate-chlorosilylene. Compound 1 has two interconnected Si atoms in formally +I and +III oxidation states. Upon treatment with Lewis acidic CuI X (X=mesityl, Cl, Br, I), electron redistribution occurs resulting in the formation of [{LSi(NDipp)Si(L)}-CuX], in which both silicon atoms are in the +II formal oxidation state. Removal of the copper center from [{LSi(NDipp)Si(L)}-CuX] by using a Lewis basic carbene led to reformation of the precursor [LSi-Si(NDipp)L]. Thus, the process is fully reversible. This showcases the first example of Lewis acid/base-induced reversible electromerism in silicon chemistry.

Stimuli Responsive Silylene: Electromerism Induced Reversible Switching Between Mono‐ and Bis‐Silylene

AbstractElectromerism is a very well‐known phenomenon in transition metal chemistry. In main group chemistry, this concept has only started getting attention recently. We report stimuli responsive low‐valent silicon compounds exhibiting electromerism. A mixed‐valent silaiminyl‐silylene1, [LSi−Si(NDipp)L] (L=PhC(NtBu)2), was synthesized in a single step from amidinate‐chlorosilylene. Compound1has two interconnected Si atoms in formally +I and +III oxidation states. Upon treatment with Lewis acidic CuIX (X=mesityl, Cl, Br, I), electron redistribution occurs resulting in the formation of [{LSi(NDipp)Si(L)}−CuX], in which both silicon atoms are in the +II formal oxidation state. Removal of the copper center from [{LSi(NDipp)Si(L)}−CuX] by using a Lewis basic carbene led to reformation of the precursor [LSi−Si(NDipp)L]. Thus, the process is fully reversible. This showcases the first example of Lewis acid/base‐induced reversible electromerism in silicon chemistry.

Cuprous Oxide (Cu2O) Based Solar Cell Thickness Dependence

The rapid advancement of devices that transform light into other energy forms has led to the growth of various solar cell structures established on silicon and other compound semiconductors. Photovoltaic devices that are efficient are required to ensure solar power's competitiveness with traditional energy sources. The most intriguing phase of copper oxides is Cu2O. There have been several findings of Cu2O-based solar cells; nevertheless, their efficiencies are quite minimal due to charge recombination at the crystal boundary and other factors. The goal of the present study is to review the effect of Cu2O thin film thickness prepared by oxidation techniques on efficiency, and then previous related work was systematically studied to investigate their structural and morphological properties. Gravimetric measurements were used to determine the thickness of Cu2O on Cu. The XRD pattern presented shows a single phase of Cu2O with no obvious impurity peaks. The finding shows that when the thickness is 26.30µm, the conversion efficiency is high; image analysis from a different method of deposition demonstrated that the films were compact throughout the entire sample surface, with no observed pinholes. The morphology of the stratum was strongly dependent on the deposition techniques.

Antifungal Agents in Wood Protection-A Review.

The biodegradation of wood and wood products caused by fungi is recognized as one of the most significant problems worldwide. To extend the service life of wood products, wood is treated with preservatives, often with inorganic compounds or synthetic pesticides that have a negative impact on the environment. Therefore, the development of new, environmentally friendly wood preservatives is being carried out in research centers around the world. The search for natural, plant, or animal derivatives as well as obtaining synthetic compounds that will be safe for humans and do not pollute the environment, while at the same time present biological activity is crucial in terms of environmental protection. The review paper presents information in the literature on the substances and chemical compounds of natural origin (plant and animal derivatives) and synthetic compounds with a low environmental impact, showing antifungal properties, used in research on the ecological protection of wood. The review includes literature reports on the potential application of various antifungal agents including plant extracts, alkaloids, essential oils and their components, propolis extract, chitosan, ionic liquids, silicon compounds, and nanoparticles as well as their combinations.

Laser-Engineered Multifunctional Graphene-Glass Electronics.

Glass electronics inspire the emergence of smart functional surfaces. To evolve this concept to the next level, developing new strategies for scalable, inexpensive, and electrically conductive glass-based robust nanocomposites is crucial. Graphene is an attractive material as a conductive filler; however, integrating it firmly into a glass with no energy-intensive sintering, melting, or harsh chemicals has not been possible until now. Moreover, these methods have very limited capability for fabricating robust patterns for electronic circuits. In this work, a conductive (160OΩ sq-1 ) and resilient nanocomposite between glass and graphene is achieved via single-step laser-induced backward transfer (LIBT). Beyond conventional LIBT involving mass transfer, this approach simultaneously drives chemical transformations in glass including silicon compound formation and graphene oxide (GO) reduction. These processes take place together with the generation and transfer of the highest-quality laser-reduced GO (rGO) reported to date (Raman intensity ratio ID /IG = 0.31) and its integration into the glass. The rGO-LIBT nanocomposite is further functionalized with silver to achieve a highly sensitive (10-9 m) dual-channel plasmonic optical and electrochemical sensor. Besides the electrical circuit demonstration,an electrothermal heater is fabricated that reachestemperatures above 300°C and continuously operatesfor over 48h.

Синтез и некоторые свойства коллоидных квантовых точек селенида ртути

The synthesis of colloidal quantum dots of mercury selenide using mercury oxide as a precursor is proposed. The proposed method is characterized by the use of a less toxic component in the reaction mixture - mercury oxide. The transmission electron microscopy method established an average diameter of 5–6 nm and the shape of quantum dots. A histogram of the size distribution of synthesized nanoparticles is presented. An important property of the synthesized nanoparticles is the crystal structure established by X-ray diffraction analysis. The established properties of the synthesized nanocrystals coincide with the literature data. The elemental composition of the nanoparticles was controlled by X-ray microanalysis. It is established that the chemical composition of quantum dots corresponds to the stoichiometric ratio of Hg elements : Se = 0,98 : 1,00. In addition, it follows from the X-ray that the oxygen content has been identified in silicon and carbon compounds, HgSe-based quantum dots do not contain traces of oxidation. The optical properties of quantum dots depend on the size of the nanoparticles. If the average diameter does not exceed 10 nm, mercury selenide particles are characterized by a monocrystalline structure with intraband absorption, the spectral energy distribution of which is subjected to dimensional quantization. As can be seen from the absorption spectra, the synthesized nanoparticles are characterized by absorption bands in the IR region, in the wavelength range up to 40 microns. The synthesized quantum dots do not possess luminescent properties, which, according to the literature data, is associated with a low probability of exciton formation for small nanoparticles (5–6 nm).

Recycling of alumina-containing sweepings for use in primary aluminium production

Aluminium is produced by electrolysis using a melt that consists of cryolite and alumina. Domestic aluminium producers are facing a shortage of alumina, which is the raw material for making primary aluminium. This gives relevance to the problem of processing industrial alumina-containing waste in order to get Al2O3 back into the electrolysis process. When doing maintenance for aluminium cells, primary aluminium producers that rely on Soderberg cells generate alumina-containing waste with a complex and varying composition. However, it contains a considerable amount of valuable components, such as Na3AlF6, Al2O3, AlF3. When the waste is collected, valuable alumina particles get mixed up with various materials (lumps of asphalt and concrete, sand). As a result, alumina gets contaminated with iron and silicon compounds (SiO2, Fe2O3) and can no longer be reused in the electrolysis process as the main source of metal. RUSAL Bratsk PJSC has developed a unit that helps reduce the concentration of these impurities in the alumina-containing waste. The focus of this paper is on examining the operation of the developed unit, as well as searching for contrast properties of the waste material which could help enhance the performance of the unit. Having analyzed the phase composition of the samples, the authors established that the waste material is mainly comprised of cryolite, chiolite, corundum, quartz, feldspar, carbonaceous matter and a process phase of the following composition: (NaF)·1,5CaF2·AlF3. High concentrations of Si (1.91 %) and Fe (0.62 %) were registered in the following size range –0.63+0.315 mm. A microscopic study helped establish the contrast properties of the material. It was found that, considering the registered distribution of impurities, reusing the maximum amount of waste in the electrolysis process would require adoption of optical and gravitational processing. The contributors to this research includes L. V. Gavrilenko, Candidate of Technical Sciences, manager at the Directorate for Aluminium Production Processes and Advances, Engineering and Technology Centre (RUSAL ETC) in Bratsk.This research was funded through Presidential Grant No. SP-306.2022.1.

Microstructural Characteristics, Modeling of Mechanical Strength and Thermal Performance of Industrial Waste Glass Blended Concrete

The need to get rid of solid waste in the environment necessitates the incorporation of waste glass powder (WGP) in mortar and concrete. The blending of WGP (G) with ordinary Portland cement (OPC) is a valorization technique that is not only cost efficient but also environmentally friendly. The replacement level is denoted as CxG10−x, where x is 0–20 wt.% at an interval of 5 wt.% in mortar (w/b = 0.4) and 0, 10, 20 and 30 in concrete (w/b = 0.42). The study investigates the effects of glass on the setting, workability, thermal resistance, microstructure, mineral phases and bond characteristics of silicon and hydroxyl-based compounds and C-O vibrations. It also provides the model equations for strength characteristics in terms of OPC, G and ages in mortar and concrete on one hand and investigates the residual strength and density of glass blended concrete at elevated temperature (550 °C) on the other. It is found that glass enhances the workability, reduces the setting time and density and enhances the residual strength and density of concrete. The presence of glass leads to the formation of coesite and microstructural distortion and decreases the Ca/Si ratio. Besides, the bond characteristics of the binder are significantly affected, while the thermal residual strength capacity in glass blended concrete (C80G20) is 40.4% and 75.14% lower than that in OPC concrete (C100G0) because of the low thermal conduction of glass particles. The optimum glass content in mortar and concrete to produce 33 MPa (28 days) and 47 MPa (90 days) is found to be 10 wt.% and 20 wt.%, respectively.

The dynamics of morphological and functional changes of face neck skin at using injectables

The article deals with the issues of face and neck skin involutional changes, which are considered to be the first and easily determined signs of the body aging. Clinical studies of the effectiveness of the therapy with medicines based on hyaluronic acid, silicon and zinc are presented. Based on the presented data, the possibility of further clinical trials of pharmacological preparations used to treat the skin of the face and neck is discussed.
 Of particular interest are data on the dynamics of expression of key biomarkers of skin aging in the combined use of silicon- and zinc-containing injectable drugs. The addition of zinc can enhance the effect of silicon compounds in the composition of these drugs.
 Organosilicon (silanol) increases the synthesis of type III collagen and elastin and has a protective effect against photodamage of the skin. An increase in the formation of type III collagen was revealed when using silicon complexes with chitinase, while an increase in the expression of TGF- and an increase in fibroblast proliferation were also revealed.
 The use of silicon- and zinc-containing drugs is a promising, but still insufficiently studied direction of therapy for involutional changes in the skin of the face and neck. Silicon and zinc in the composition of drugs for anti-aging therapy can have a synergistic effect, affecting a number of important molecular mechanisms of skin aging.

Homogeneous reduction for heavy metals from pickling sludge with aluminum nitride from secondary aluminum dross in aluminosilicate melt ‘solution’ environment

Secondary aluminum dross (SAD) and pickling sludge were hazardous wastes . In this work, aluminum nitride (AlN) from SAD was used to reduce heavy metals from pickling sludge by pyrometallurgy . Reaction mechanism was studied after exploring transformation of heavy metals and AlN during reaction process. It was found that reduction reaction between heavy metals and AlN was homogeneous reduction reaction. When mixture was heated to 1000 °C, heavy metals and AlN were distributed independently, and reduction reaction had not occurred. When mixture was heated to 1300 °C, heavy metals and AlN entered aluminosilicate network, and homogeneous reduction reaction occurred. Half of the heavy metals were reduced into metallic state and mixed with the dross. When the mixture was heated at 1400 °C for 1 h, metal block separated from dross. Reduction rates of Fe, Cr and Ni were 94%, 88% and 100%. Like water solution, aluminosilicate melt could dissolve heavy metal oxides , aluminum compound (AlN, Al 4 C 3 , etc.) and silicon compound (Si 3 N 4 , SiC, etc.). This work proposed a novel homogeneous reaction environment, aluminosilicate melt ‘solution’ environment, which had a significant effect not only on heavy metals reduction, but also on other high temperature oxidation-reduction. • AlN in SAD was used to reduce heavy metals by pyrometallurgy. • Reduction rates of Fe, Cr and Ni were 94%, 88% and 100%. • Reaction mechanism was studied by exploring AlN and heavy metals transformation. • Reaction between AlN and heavy metals was homogeneous reduction reaction. • Aluminosilicate melt ‘solution’ was proposed for homogeneous reaction.

Copper(II) Ion Promoted Reverse Solvatochromic Response of the Silatrane Probe to Spectral Shifts: Preferential Solvation and Computational Approach.

The unique solvatochromic attitude of an analyte owing to its coordination with metal ions in solvents of different polarities is challenging. Herein, we introduce two new solvatochromic 4-(pentan-3-yl) benzaldehyde-based triazolyl silatrane probes (5 and 6). The solvatochromic behavior of both probes 5 and 6 was studied using Reichardt's E (30) and the Kamlet-Taft empirical scale by UV-visible spectra in 14 solvents (hydrogen-bond donor (HBD) and non-HBD), and the results show that probes 5 and 6 exhibit reverse solvatochromism. Probe 5 witnessed an enhancement in this behavior upon coordination with the Cu2+ ion in MeCN/MeOH solvents due to the intramolecular charge transfer (ICT) process. Interestingly, the binding of probe 5 with Cu2+ ions resulted in an instant color change in MeCN and MeOH from pale yellow to light blue and brown-red, respectively, which can be easily detected by the "naked eye". A solvatochromic study of the complex 5-Cu2+ in binary mixtures of polar aprotic and polar protic solvents (MeCN/MeOH) discloses that the latter are more preferred over polar aprotic solvents in the solvation microsphere. The entire metal coordination process of probe 5 toward the Cu2+ ion can be visualized and was further evaluated by UV-vis/fluorescence spectral titrations, Fourier transform infrared (FT-IR) spectroscopy, and theoretical calculations employing density functional theory (DFT) and time-dependent-DFT (TD-DFT). The proposed analytical approach is believed to play a crucial role in the solvatochromic study of higher coordinated silicon compounds, which may be utilized to develop a solvent-dependent sensor.

The Effect of Foliar–Applied Silicon Compounds on Reducing Seed Shattering and Improve Seed and Oil Yield of Canola (Brassica napus L.)

The Effect of Foliar–Applied Silicon Compounds on Reducing Seed Shattering and Improve Seed and Oil Yield of Canola (Brassica napus L.)

1946 and the Early History of Hydrosilylation.

Three events occurred in the second half of 1946 in three adjoining US States (NJ, NY, and PA) which marked the birth of Hydrosilylation Technology. They occurred before the landmark 1957 JACS paper and the 1958 issued US patent by Speier et al. and before Chalk and Harrod named the reaction. First, on 27 June 1946, Mackenzie et al., of Montclair Research Corp., applied for a patent to prepare addition compounds of hydridosilanes and unsaturated organic compounds. Then, on 9 October 1946, Wagner and Strother of Union Carbide Corp. applied for a patent on a process to produce organic compounds of silicon with Si–C bonds by reacting a hydridosilane and an alkene or alkyne in the presence of a catalyst metal of the platinum group. Finally, Sommer et al., submitted a paper on peroxide-catalyzed hydrosilylation to JACS on 17 December 1946. It was published in January 1947. The landmark patent interference § and priority § case law associated with the Mackenzie et al. and Wagner et al., applications is well known to patent attorneys. This presentation will retrace the origins of hydrosilylation and report events (1946–1960) in the history of the reaction that are most probably unknown to most authors and presenters of hydrosilylation investigations. George Wagner’s contribution to the birth of this technology is also highlighted.

Evaluation of mechanical and wear properties of AA6063/(Si3N4)6%–12% /(CuN2O6)2%–4% composite via PM route and optimization through robust design technique

The study is to investigate the physical, mechanical, and tribological properties of Al6063 alloy reinforced by Silicon Nitride (Si3N4) & compound Copper Nitrate (CuN2O6) processed via Powder Metallurgy (PM) Techniques. Incorporation of reinforcement in matrix material ranged from 6 to 12% Si3N4 in a 6-step interval, and 2 to 6%CuN2O6 in a two-step interval. The characterizations were made on the PM produced specimens using OM, EDS, XRD and hardness. The reinforcement particles were distributed uniformly is attributed by homogeneous mixer of matrix and reinforcements. The tests were carried out in accordance with ASTM Standards on the Al6063 alloy and its composites. The test findings show that as the reinforcing percentage of ceramic and inorganic compound is increased, properties such as hardness and density rise monolithically and considerably. The dispersion of Si3N4 and CuN2O6 reinforcement in the AA6061 matrix was ensured by x-ray diffraction patterns. In comparison to the base alloy, the hardness of AA6063/12%Si3N4/6% CuN2O6 improved by 88% due to the mismatch of thermal expansion between the Al matrix and reinforcement causes huge internal stress, causing the aluminium matrix to deform plastically to lodge the smaller volume expansion of Si3N4 and CuN2O6 particles. The dry sliding wear test was carried out on a tribometer with a pin-on-disc arrangement, and the findings show that the composite has a higher wear resistance. The Taguchi design of experiments was used to investigate the solution containing parameters employing an orthogonal array, the signal-to-noise ratio, and analysis of variance. The weight percentage of Si3N4/CuN2O6 compound and the relationship between wt% of reinforcement and applied load had the highest impact on composite wear resistance, accounted for 31.66%. Before and after the wear morphology during the wear test, images from a scanning electron microscope and energy dispersive microscopy were used to examine the manufactured composites.

Synthesis of an N‐Heterocylic Boryl‐Stabilized Disilyne and Its Application to the Activation of Dihydrogen and C−H Bonds

AbstractThe synthesis of low‐valent silicon compounds that enable the activation of small molecules has been of great current interest. Reduction of N‐heterocyclic boryltribromosilane (NHB)SiBr3 (2, NHB=[ArN(CMe)2NAr]B, Ar=2,6‐iPr2C6H3) with three equiv. of lithium in diethyl ether yielded the NHB‐stabilized disilyne (NHB)Si≡Si(NHB) (3). Disilyne 3 slowly reacted with toluene, leading to the activation of one benzylic C−H bond and one C=C double bond with the formation of 4. Treatment of 3 with dihydrogen under 1 atm at room temperature resulted in the exclusive formation of the first boryl‐stabilized 1,2‐dihydrodisilene. Compounds 3–5 have been characterized by single‐crystal X‐ray diffraction studies, which indicated the co‐planarity of the B−Si−Si−B plane with the NHB rings in compounds 3 and 5. DFT calculations indicated the significant π electron delocalization of the Si−Si multiple bonds to the B−N bonds in NHB rings.

Synthesis of an N-Heterocylic Boryl-Stabilized Disilyne and Its Application to the Activation of Dihydrogen and C-H Bonds.

The synthesis of low-valent silicon compounds that enable the activation of small molecules has been of great current interest. Reduction of N-heterocyclic boryltribromosilane (NHB)SiBr3 (2, NHB=[ArN(CMe)2 NAr]B, Ar=2,6-iPr2 C6 H3 ) with three equiv. of lithium in diethyl ether yielded the NHB-stabilized disilyne (NHB)Si≡Si(NHB) (3). Disilyne 3 slowly reacted with toluene, leading to the activation of one benzylic C-H bond and one C=C double bond with the formation of 4. Treatment of 3 with dihydrogen under 1 atm at room temperature resulted in the exclusive formation of the first boryl-stabilized 1,2-dihydrodisilene. Compounds 3-5 have been characterized by single-crystal X-ray diffraction studies, which indicated the co-planarity of the B-Si-Si-B plane with the NHB rings in compounds 3 and 5. DFT calculations indicated the significant π electron delocalization of the Si-Si multiple bonds to the B-N bonds in NHB rings.

The effect of microfertilizers on the morphometric parameters of plants and the duration of the growing season of lettuce varieties (Latuca sativa L.)

In the conditions of the Rostov region on ordinary chernozems, the effect of foliar top dressing with microfertilizers on the formation of the vegetative part and the timing of harvesting varieties of lettuce (Latuca sativa L.) in open ground under irrigation was studied. The issues of forming indicators of the average weight of 1 plant, as well as the height associated with it, depending on the applied microfertilizers, are considered. A general positive trend has been established to accelerate maturation, increase the average weight and height of plants when using foliar top dressings with an ambiguous varietal response to them. Ecofus, Siliplant and Nagro, containing silicon compounds, increase the average weight by more than 140% and the height of plants by 5.5-5.7 cm in comparison with the control. The maximum indicators were noted for the varieties Abrek and Eralash

Hazard assessment of pesticides’ application in agroecosystems

The danger assessment of using pesticides and the effectiveness of reducing the pesticide load in agrocenoses of grain crops and fodder beet according to the indicators of predicted pollution and agro-eco-toxicological index (AETI) was carried out. A significant decrease in the predicted agrocenoses' contamination indicators with pesticides and AETI was found with a decrease in the fungicides consumption rates by 50% and insecticides by 20% when combined with silicon compounds. The comparison of indicators of predicted pollution and AETI for grain crops agrocenoses in different natural and climatic zones was carried out. The greatest danger is the use of pesticides in the dry-steppe zone of chestnut soils due to their low self-cleaning ability.