Search Results (20)

From the point of view of farming utilization, investigations on the recognition of the mineral composition of sedges appears important, appropriate and useful. Sedges are often found in many meadow and pasture communities. It is therefore worth paying attention to the mineral content of their tissues and their possible impact on the organisms of farm animals such as pigs. The basic objective of this study was to determine the concentration of selected macro and microelements: phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), iron (Fe), silicon (Si), copper (Cu), zinc (Zn), chrome (Cr) and nickel (Ni) in the biomass of seven sedge species, potentially used as fodder, commonly occurring in natural sites in Central Europe. The material was collected twice during one growing season in the Krześniczka (N 52°37′14′ E 14°46′06′)—lubuskie voivodeship. The first harvest was carried out at the beginning of May, during the shooting and earring phase. The collected plant material included stems and leaves. The second harvest—the end of June—was collected at a time when the seedlings were developing flowers and young fruits, and their vegetative organs were developing dynamically. In June, the collected material represented organs in all possible development phases. The collected material was dried at a temperature of 65 °C, ground, and analyzed. The obtained results showed a difference in the content of microelements between the May and June harvest dates in the dry matter of all analyzed sedge species, which differed statistically significantly only in relation to copper. The harvest date had a statistically significant impact on the change in the content of macroelements in the dry matter of all analyzed sedge species and was associated with a decrease in the content of phosphorus, magnesium and calcium, while in the case of silicon, the delay in mowing resulted in an increase in the content of this element. Full article

Petrological, geochronological, and geochemical analyses of mafic rocks in northern Liaoning were conducted to constrain the formation age of the Proterozoic strata, and to further study the source characteristics, genesis, and tectonic setting. The mafic rocks in northern Liaoning primarily consist of basalt, diabase, gabbro, and amphibolite. Results of zircon U-Pb chronology reveal four stages of mafic magma activities in northern Liaoning: the first stage of basalt (2209 ± 12 Ma), the second stage of diabase (2154 ± 15 Ma), the third stage of gabbro (2063 ± 7 Ma), and the fourth stage of magmatic protolith of amphibolite (2018 ± 13 Ma). Combined with the unconformity overlying Neoproterozoic granite, the formation age of the Proterozoic strata in northern Liaoning was found to be Paleoproterozoic rather than Middle Neoproterozoic by the geochronology of these mafic rocks. A chronological framework of mafic magmatic activities in the eastern segment of the North China Craton (NCC) is proposed. The mafic rocks in northern Liaoning exhibit compositional ranges of 46.39–50.33 wt% for SiO₂, 2.95–5.08 wt% for total alkalis (K₂O + Na₂O), 6.17–7.50 wt% for MgO, and 43.32–52.02 for the Mg number. TiO₂ contents lie between 1.61 and 2.39 wt%, and those of MnO between 0.17 and 0.21 wt%. The first basalt and the fourth amphibolite show low total rare earth element contents. Normalized against primitive mantle, they are enriched in large ion lithophile elements (Rb, Ba, K), depleted in high field strength elements (Th, U, Nb, Ta, Zr, Ti), and exhibit negative anomalies in Sr and P, as well as slight positive anomalies in Zr and Hf. The second diabase and the third gabbro have similar average total rare earth element contents. The diabase shows slight negative Eu anomalies (Eu/Eu* = 0.72–0.88), enrichment in large ion lithophile elements (Ba), depletion in Rb, and slight positive anomalies in high field strength elements (Th, U, Nb, Ta, Zr, Hf, Ti), with negative anomalies in K, Sr, and P. The gabbro is enriched in large ion lithophile elements (Rb, Ba, K), depleted in high field strength elements (Th, U, Nb, Ta, Zr, Hf), and exhibits positive anomalies in Eu (Eu/Eu* = 1.31–1.37). The contents of Cr, Co, and Ni of these four stages of mafic rocks are higher than those of N-MORB. The characteristics of trace element ratios indicate that the mafic rocks belong to the calc-alkaline series and originate from the transitional mantle. During the process of magma ascent and emplacement, it is contaminated by continental crustal materials. There are residual hornblende and spinel in the magma source of the first basalt. The other three magma sources contain residual garnet and spinel. The third gabbro was formed in an island arc environment, and the other three stages of mafic rocks originated from the Dupal OIB and were formed in an oceanic island environment. The discovery of mafic rocks in northern Liaoning suggests that the Longgang Block underwent oceanic subduction and extinction in both the north and south in the Paleoproterozoic, indicating the possibility of being in two different tectonic domains. Full article

A series of metal- and silica-containing carbon-based nanocomposites were synthesized by pyrolysis of a resorcinol–formaldehyde polymer modified with metal oxide/silica nanocomposites (MxOy/SiO₂, where M = Mg, Mn, Ni, Cu and Zn) via the thermal oxidative destruction of metal acetates adsorbed on highly dispersed silica (A380). The concentration of metals was 3.0 mmol/g SiO₂. The phase composition and morphological, structural and textural properties of the carbon materials were analyzed by X-ray diffraction, SEM, Raman spectroscopy and low-temperature N₂ adsorption. Thermal decomposition under a nitrogen atmosphere and in air was analyzed using TG–FTIR and TG–DTG–DSC techniques to determine the influence of the filler on the decomposition process. The synthesized composites show mesoporous structures with high porosity and narrow pore size distributions. It could be shown that the textural properties and the final composition of the nanocomposites depend on the metal oxide fillers of the precursors. The data obtained show that nickel and copper promote the degree of graphitization and a structural order with the highest porosity and largest specific surface area of the hybrid composites. The good adsorption properties of the obtained materials were shown for the recovery of p-chlorophenol and p-nitrophenol from aqueous solutions. Full article

Degradation of industrial machinery through wear can be mitigated with the deposition of protective coatings to reduce maintenance costs and prolong their service lifespans. Electroless nickel-based composite coatings is one possible method used to provide this protection. The addition of Tribaloy (CoMoCrSi alloy) particles has been found to produce composite coatings with high toughness. In this work, electroless Ni-P-Tribaloy composite coatings were plated on AISI 1018 steel substrates and subjected to low-stress abrasion tests following ASTM G65 standards to investigate the abrasion of the coating. The test was performed at 10 revolution increments, with a 45 N applied load, until coating failure was observed and the measured abrasion was reported as volume loss. The two Ni-P-Tribaloy coating samples lasted for 90 and 100 revolutions, exhibiting a wear rate of 0.170 mm³ per revolution, compared to 0.135 mm³ per revolution for the Ni-P coatings. The abrasive wear mechanism in the Ni-P-Tribaloy coating was found to be plowing of the matrix around the Tribaloy particles, followed by the removal of the particles once they are protruding, which subsequently contributes to the three-body wear of the coating. The particle removal was accelerated at the coating particle-matrix interface. It is concluded that the size of the Tribaloy is a major factor, and we recommend that further studies be carried out using finer particles to improve the wear resistance of the Ni-P-Tribaloy coating. Full article

The article presents the results of mechanical testing of Ni-P/Si₃N₄ nanocomposite and hybrid Ni-P/Si₃N₄/graphite coatings deposited on AW-7075 aluminum alloy using the chemical reduction method. In terms of mechanical testing, microhardness was measured, and surface roughness and adhesion of the coatings to the aluminum substrate were determined using the “scratch test” method. The surface morphology of the deposited layers was also analyzed using light microscopy and scanning electron microscopy. Samples made of AW-7075 aluminum alloy with electroless deposited Ni-P/Si₃N₄ nanocomposite, Ni-P/graphite composite and hybrid Ni-P/Si₃N₄/graphite coatings with different content of dispersed phases were tested, and also, for comparison purposes, the Ni-P layer that constituted the matrix of the tested materials. Reinforcing phases in the form of silicon nitride nanoparticles and graphite particles were used in the layers. The purpose of the research was a thorough characterization of the coating materials used on aluminum alloys in terms of mechanical properties. Graphite is considered in this paper as it enables the reduction of the coefficient of friction through its lubricating properties. Unfortunately, graphite is difficult to use in selected layers as the only dispersion phase, because it has much lower hardness than the Ni-P coating. For this reason, a layer with a single dispersion phase in the form of graphite will be characterized by worse mechanical properties. It is necessary to add particles or nanoparticles with hardness higher than the base Ni-P coating, e.g., Si₃N₄, which improve the mechanical properties of the coating. The presented analyses of the results of the conducted research complement the previous studies on selected properties of nanocomposite layers with an amorphous structure and supplement the knowledge regarding their suitability for application to aluminum machine parts. Full article

Seventeen new experimental filler metals from eight different alloy systems based on Fe–P–X and Mn–Fe–P–X (X = B, C, Si in various combinations) were created and experimented with. DSC analyses were performed to determine the solidus and liquidus temperatures and the melting ranges. Hardness measurements of the alloys were performed in the as-cast state. The alloys contain primary and eutectic intermetallic compounds that make them very hard with average hardness values ranging from 590 HV10 to 876 HV10. The wettability was determined at 1000 °C, 1040 °C and 1080 °C on C22 non-alloy steel and 15CrNiS6 low-alloy steel in Ar 4.6 and 78 vol% H₂-22 vol% N₂ atmospheres. The results show good wettability at T = 1080 °C in both atmospheres, as the contact angles were mostly ≤30°. Thirteen alloys exhibit very good wettability with average contact angles of ≤15.5°. Nine alloys exhibit excellent wettability with their average contact angles being ≤10°. Wettability improves at higher temperatures. The liquid alloys are reactive to solid steels and form a diffusion joint. Diffusion of P, B, C, and Si from the filler metal into the base material dealloys the composition of the melt near the joint interface. For the same reason, a continuous layer of solid solution forms on the joint interface. When brazing with filler metals rich in carbon, strong carburisation of steels can be observed near the joint. Full article

Electroless nickel composite coatings have the potential for high-temperature tribological applications, and a combination of high wear resistance and low friction factor is one of the desirable solutions but still a tricky problem. The addition of self-lubricating WS₂ and hard Si₃N₄ nanoparticles to the Ni-P coatings is expected to obtain good high-temperature tribological performance. In this work, Ni-P-Si₃N₄-WS₂ composite coatings with various contents of WS₂ nanoparticles were prepared using electroless plating and subsequently annealed at 400 °C in an inert atmosphere. The tribological properties of the coatings were evaluated using a ball-on-disc wear instrument at operating temperatures from 25 to 600 °C. The microstructure, chemical composition, and surface morphology of the coatings were characterized by X-ray diffractometry (XRD), energy disperse spectroscopy (EDS), and scanning electron microscopy (SEM). Upon increasing the WS₂ dosage in the bath, the WS₂ content in the coating increased and the micro-hardness of the as-plated coating increased from 539 to 717 HV. After heat treatment, the coating underwent a crystallization process, and the hardness increased from 878 to 1094 HV. The main wear mechanism of the coating changed from adhesive wear in the as-plated state to abrasive wear in the annealed state. The annealed Ni-P-Si₃N₄-WS₂ coating with a WS₂ dosage of 2.5 g/L in the bath exhibited excellent mechanical properties, with a hardness of 10.9 GPa, a friction coefficient of ~0.51, and a wear rate of 8.4 × 10⁻¹⁵ m³N⁻¹⋅m⁻¹ at room temperature, and maintained optimal performance at high temperatures. At operating temperatures of 200, 400, and 600 °C, the form of wear was adhesive wear for coatings with a WS₂ dosage <1.5 g/L and abrasive wear for coatings with a WS₂ dosage ≥1.5 g/L. The synergism of WS₂ and Si₃N₄ particles refined the grains of the Ni-P matrix in as-plated coatings and obviously reduced the friction coefficient of friction pairs in annealed coatings at all operating temperatures. Full article

In recent years, Cu-Ni deposits have been discovered at different localities in the Eastern part of the Kunlun orogenic belt such as Xiarihamu, Langmuri, Shitoukengde, and Wenquan. Eclogites are usually exposed in the areas associated with these deposits, thereby implying a certain coupling relationship between the Cu-Ni deposits and eclogite distribution. In this study, eclogite samples from the Xiarihamu and Langmuri areas were analyzed using petrogeochemistry, U-Pb zircon geochronology, and electron probe microanalysis (EPMA). Further, eclogite protolith properties, the formation environment, and the metallogenic mechanism were also investigated. Geochemically, eclogite is rich in MgO and FeO and low in alkali and SiO₂. Its m/f ratios are 0.72 to 1.53 and Mg^# values of 42 to 61. Overall, the chondrite-normalized rare-earth elements (REE) patterns showed characteristics of weak enrichment with LREE, weak negative Eu anomalies, relative enrichment of large-ion lithophile elements such as K and Rb, active incompatible element Th, the depletion of high-field strength elements Nb, Ta, Zr, and Hf, and V-shaped valleys caused by depletion in Sr, P, and Ti. These geochemical characteristics indicated that the protolith is highly differentiated Fe gabbro that formed in a continental margin type of rift environment. The EPMA analyses showed that the composition of garnet consists of almandite and grossularite, and omphacite often contains augite. Geochronological investigations showed that the peak metamorphic age of eclogite in Xiarihamu and Langmuri is 415.6 ± 2.7 Ma (MSWD = 0.43, n = 16) and 449.1 ± 8.5 Ma (MSWD = 0.88, n = 19), which are related to the early Paleozoic orogenic cycle and formed slightly earlier than the formation of the magmatic liquation type of Cu-Ni deposits in this area. On the basis of spatial coupling, formation age approximation, and geochemical correlation between eclogite and mafic rock masses, in combination with the previous research results of earlier work, it has been considered that the Cu-Ni ore deposits in the East Kunlun Range were formed in the post-collisional extension environment after the deep subduction of the continental crust. The ultra-high-pressure metamorphic melange formed by continental deep subduction or the enriched mantle formed by crust-mantle metasomatism was partially melted to form sulfur-rich mafic–ultramafic magmas in the post-collision extension environment. During the deep subduction of the continental crust, a large amount of crust-derived sulfur was brought into the mantle, which is the key factor for the mineralization of Cu-Ni ore in the region. Full article

The exposure of plants to weak magnetic fields (MFs) of various intensities and for different times is increasingly adopted to sustainably enhance plant growth in plant-based applications such as modern agriculture, phytoremediation and biogas production. However, little is known about the effects of MF exposure on plant chemical composition, and in turn on related ecosystem processes, such as the transfer of potentially toxic elements along food chains and the decomposition of organic matter. To fill this gap, the present research, through the study of the chemical composition of four edible crops (leaves of lettuce, parsley and basil, and fruits of tomato) differently exposed to weak MFs (75 Hz; 1.5 mT), aimed at evaluating the overall effects of the exposure on ecosystem processes. In particular, several essential (B, C, Ca, Cu, K, Fe, Mg, Mn, Mo, N, Ni, P, S, Zn), beneficial (Co, Na, Se, Si) and non-useful (Al, As, Ba, Cd, Cr, Li, Pb, Sr, Ti, V) elements, together with chemical compounds and derived parameters (soluble sugars, starch, chlorophylls, flavonoids, anthocyanins, nitrogen balance index), indicators of plant metabolism and health, and litter decomposability traits (C/N, C/P), were analyzed. Notwithstanding the expected variations in the observed effects among species and MF exposure conditions, the obtained results highlight a general decrease in most of the studied parameters (with the exception of those related to litter decomposability), attributable to a lower absorption/accumulation of the studied chemical elements and to a reduced synthesis of metabolites. The largest average reduction was observed for the non-useful elements, which outweighs the reduction in essential and beneficial elements and provides for an important MFinduced effect, considering their toxic, persistent and biomagnificable characteristics. Similarly, the induced increases in C/N and C/P ratios indicate the production of litter more recalcitrant to the decomposition process, suggesting that weak MF treatments may be useful to enhance soil C storage and reduce CO2 emissions. Full article

Ni–Co–P/Si₃N₄ composite coatings were fabricated over an aluminum–silicon (Al–Si) substrate using a pulse-current electroplating process, in which the rapid deposition of an intermediate nickel–cobalt layer was used to improve coating adhesion. The microstructure, mechanical, and tribological behaviors of the electroplated Ni–Co–P/Si₃N₄ composite coating were characterized and evaluated. The results revealed that the electroplated Ni–Co–P/Si₃N₄ composite coating primarily consisted of highly crystalline Ni–Co sosoloid and P, and a volumetric concentration of 7.65% Si₃N₄. The electroplated Ni–Co–P/Si₃N₄ composite coating exhibited hardness values almost two times higher than the uncoated Al–Si substrate, which was comparable to hard chrome coatings. Under lubricated and dry sliding conditions, the electroplated Ni–Co–P/Si₃N₄ composite coating showed excellent anti-wear performance. Whether dry or lubricated with PAO and engine oil, the composite coating showed minimum abrasive wear compared to the severe adhesive wear and abrasive wear observed in the Al–Si substrate. Full article

Electroless Nickel–Phosphorus (Ni-P) coating is recognized mostly for its outstanding corrosion and wear-resistant behavior. The intrinsic corrosion and wear-resistant properties of Ni-P-based coating could be further upgraded by incorporating appropriate second-phase additive particles into the coating matrix. However, such properties of the Ni-P-based coating greatly rely on the surface and microstructural evolution arising with the co-deposition of the additive particles. In this study, submicron Si₃N₄ (average size ~200 nm) and nano Si₃N₄ (average size ~20 nm) particles were incorporated while depositing a Ni-P alloy in a low-carbon steel substrate to develop the Ni-P-Si₃N₄ composites through the electroless coating method. The 20 nm Si₃N₄-incorporated composite coating constituted fewer defects such as cavities and micropores on the surface, but such defects significantly appeared on the surface of the composite after the incorporation of 200 nm Si₃N₄ nanoparticles. Subsequently, the composite Ni-P-Si₃N₄, developed with the co-deposition of 20 nm nanoparticles, is enriched with enhanced anticorrosion characteristics compared with the composite developed with 200 nm nanoparticles. The enhancement of anticorrosion behavior was attributed mainly to the Si₃N₄ nanoparticles that covered the substantial volume of the coating and led to inhibit the formation of corrosion active sites such as defects and metallic Ni phase. Full article

The importance of mineral elements, both in animal and plant nutrition, has been well recognized, but, in the case of sedges, the mineral composition is relatively poorly known. Studies usually relate to the content of the elements in sedge communities, or sward or hay communities with sedge participation, and rarely of Carex representatives. The objective of our study was to determine the concentrations of C, N, Ca, P, Mg, Na, K, Si, Cu, Zn, Mn, Fe, Cr and Ni in the biomass of 11 Carex species commonly occurring on natural sites of Central European lowland. Interspecific differentiations have been observed in concentrations of the major and trace elements among studied sedge species. The elemental composition of examined Carex species is diversified but generally similar to the composition of grasses. The study shows that sedges can increase fodder value and, therefore, they should be considered in meadow management as a valuable component of economically important meadow communities. Moreover, the data reported herein can be used for modelling the phytoaccumulation of various elements in the biomass of sedges. This will help in creating different patches suitable for obtaining adequate fodder. Our results can supplement current knowledge concerning the fodder value of meadows with sedge participation. Full article

HZSM-5 (MFI type) of composition (H_x)[Al³⁺_xSi_12−xO₂₄] × wH₂O and nanocomposites NA/HZSM-5, NA:M/HZSM-5 (NA—nanoscale anatase; M = V, Ni, Ag) with Si/Al = 12, 25, 40, 300 (sp.gr. Pnma or P2₁/n; z = 8), as well as zeolites [(Ti⁴⁺_xSi_12−xO₂₄] × wH₂O (TS) with Si/Ti = 47, 53, 73.5 (sp.gr. Pnma) were studied by XRPD, XAS, FTIR-spectroscopy, BET, XPS, SEM, EDX, TPD, UV–VIS-spectroscopy, UV–DRS, and chemiluminescence methods. The results obtained together with photocatalytic, adsorption, antimicrobial, catalytic properties were analyzed using crystallochemical concepts and literature data. It was shown that NA or NA:M introduction into HZSM-5 leads, respectively, to the photodegradation of MeO dye in the UV region or difenoconazole in the visible range, and contributes to the appearance in the dark of adsorption (almost complete extraction of P(V), As(V), and Se(V) from aquatic environment) and bacteriostatic properties in respect to Staphylococcus epidermidis, Bacillus antracoides, and Escherichia coli for NA:Ag/HZSM-5(40, 300). The presence of titanium ions in NA nanoparticles on the HZSM-5 surface improves the catalytic activity in ethanol and propane (the best performance for NA/HZSM-5(25) and NA/HZSM-5(40), respectively) conversion. Determination of the composition (surface and bulk) and structure (statistical and local) of TS zeolites together with the found correlations made it possible to propose new catalysts in the reactions of propane, ethanol, and allyl chloride conversion. Full article

Ni-P-SiC composite coating was prepared on 45 steel surfaces through sandblasting and scanning electrodeposition to explore the relationship between element penetration region and composite coating properties. The single-factor control variable method with particle concentration as the research variable was used. Results showed that with the gradually increasing concentration of SiC nanoparticles, a trend of first increasing and then gradually decreasing was observed for the surface and cross-sectional microstructure of the coating, interpenetration ability of the elements, adhesion performance, and corrosion resistance. The best deposition quality of the coating was obtained when the concentration of SiC nanoparticles was 3 g·L⁻¹. For cross-sectional microstructure, the scratch test revealed that the maximum coating thickness was 17.3 μm, the maximum range of elemental penetration region was 28.39 μm, and the maximum adhesion of the composite coating was 36.5 N. The electrochemical test showed that the composite coating had a −0.30 V self-corrosion potential and 8.45 × 10⁻⁷ A·cm⁻² self-corrosion current density, the slowest corrosion rate. In addition, the composite coating had the best corrosion resistance and the largest impedance arc radius corresponding to an equivalent impedance value R₂ of 3108 Ω. Full article

The article presents the results of mechanical and tribological tests of Ni-P/Si₃N₄ nanocomposite coatings deposited on the AW-7075 aluminum alloy using the chemical reduction method. The influence of the chemical composition on the Vickers microhardness determined by the DSI method was examined. The nanocomposite layers were made of Si₃N₄ silicon nitride in a polydisperse powder with a particle size ranging from 20 to 25 nm. The influence of the content of the dispersion layer material on the adhesion to the substrate was analyzed. The abrasive wear was tested and determined in the reciprocating motion using the “ball-on-flat” method. The surface topography was examined by the contact method with the use of a profilometer. Based on the obtained test results, it was found that the Ni-P/Si₃N₄ layers produced in the bath with the Si₃N₄ nanoparticle content in the amount of 2 g/dm³ are more resistant to wear and show greater adhesion than the Ni-P/Si₃N₄ layers deposited in the bath with 5 g/dm³ of the dispersion phase. NiP/Si₃N₄ layers provide protection against abrasive wear under various loads and environmental conditions. Full article