Diffraction Methods Research Articles

Structural, spectroscopic and electrochemical characterizations of new 2,5-bis(phosphoranyl)-3,6-diaminoquinones

Cu(II) catalyzed open air reactions of 2,5-bis(-P(O)R2))-3,6-dichloro-hydroquinones (R = Ph or iPr) with selected primary amines or ammonia proceeded with oxidation of the hydroquinone ring and substitution of chlorines by the amino groups. The products of these reactions were 2,5-bis(-P(O)R2))-3,6-di(-NHR’)-quinones (1a, R = Ph, R′ = Cy; 1b, R = iPr, R′ = Cy; 2a, R = Ph, R′ = –CH(CH2OH)2; 2b, R = iPr, R′ = –CH(CH2OH)2; 3a, R = Ph, R′ = –CH2CH(OH)CH2OH; 3b, R = iPr, R′ = CH2CH(OH)CH2OH; 4a (R = Ph, R′ = H; 4b, R = iPr, R′ = H). They were isolated as bright orange or yellow solids in moderate/good yields. The compounds were characterized by multinuclear (1H,13C,31P) NMR, FT-IR, UV–Vis, high resolution mass-spectrometry, and cyclic voltammetry. Compounds 1b, 2a, 3a and 4a,b were also characterized by single crystal X-ray diffraction methods.

Synthesis and BSA binding study of the Cu(II) complex and applications of it to enhance catalytic activity for C(Sp2)-H bond functionalization and for the synthesis of polyhydroquinolines

Among the various copper-catalyzed coupling reactions, C–S and C–N bond-forming reactions have carried off plentiful recognition due to their demand in the synthesis of molecules having biological and pharmaceutical impact. Organo-copper complex has an incontestable supremacy over the other catalytic complex due to its low cost and the use of readily accessible and stable ligands. As a consequence and in continuation of our explorative studies in this direction, an efficient and novel organo-copper complex has been synthesized and characterized by spectroscopic (NMR, FT-IR) and single crystal X-ray diffraction (XRD) methods. The synthesized stable metal complex has fascinating physical, chemical, biological and catalytic properties. In the chemical exploration refer to protein-metal interactions; we have often used Bovine Serum Albumin (BSA) protein. The synthesized copper complex has the potential to form coordinate bonds with functional groups present in BSA, together with amino acid residues and the protein backbone. The binding of metal complexes to BSA has outstanding imputation in medicinal chemistry. For enhancement of the catalytic activity of the organo-copper complex, we have evaluated it in carbon-hetero bond formation reactions where it proffered an influential tool for the establishment of C–S and C–N bonds.

Plasma Spraying NiCoCrAlY-Cr2O3-AgMo Coatings: Fabrication and Tribological Mechanisms

The increasing demand for high-performance aircraft engines has led to a greater emphasis being placed on advanced sealing coating technologies. Developing long-life, self-lubricating, and wear-resistant coatings is of significant research value. This study focuses on the fabrication of a novel self-lubricating and wear-resistant NiCoCrAlY-Cr2O3-AgMo composite coating. This coating was deposited onto a GH4169 substrate utilizing plasma spraying. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD) methods were employed to characterize the elemental composition and microstructure of the fabricated NiCoCrAlY-Cr2O3-AgMo composite coating. Microhardness measurements across the coating cross-section indicated a gradual increase in hardness from the GH4169 substrate to the NiCoCrAlY-Cr2O3-AgMo coating. The average hardness of the GH4169 substrate was 413.92 HV0.2, while the CoNiCrAlY bonding layer region exhibited an average hardness of 467.60 HV0.2. The NiCoCrAlY-Cr2O3-AgMo coating itself demonstrated an average microhardness of 643.22 HV0.2. Room temperature friction tests indicated that the average coefficient of friction (COF) of the GH4169 substrate was 0.665. In contrast, the NiCoCrAlY-Cr2O3-AgMo coating exhibited a significantly lower average COF of 0.16, representing a 75.94% reduction compared to the uncoated GH4169 substrate. High-temperature friction tests were conducted at 400 °C, 500 °C, and 600 °C, indicating average COF values of 0.438, 0.410, and 0.268, respectively, for the NiCoCrAlY-Cr2O3-AgMo coating. Specifically, at 600 °C, the formation of a lubricious NiMoO4 tribofilm on the coating surface was observed. This tribofilm effectively reduced the wear rate of the GH605 pin to 2.78 × 10−6 mm3/N·m, highlighting the potential of the NiCoCrAlY-Cr2O3-AgMo coating to reduce wear in high-temperature sliding contact applications.

Preparation, characterization and thermal properties of the PS+Si based polymer nanocomposites

Polymer nanocomposites based on polystyrene and polycrystalline Si nanoparticles have been successfully synthesized using the solution-casting method. The scanning electron microscope and x-ray diffraction methods show that the Si nanoparticle size in the obtained nanocomposite was up to 50 nm. The thermostability of the obtained nanocomposite was studied depending on the concentration of Si nanoparticles in the PS matrix. It was found that Si nanoparticles that are distributed homogeneously in the polymer matrix act as a thermal barrier. By adding 3% Si nanoparticles into polystyrene polymer, the thermal degradation temperature of PS increases by 20°, and the decomposition rate reduces from −42,460 mg/min to −35,099 mg/min. In addition, it was shown that Si nanoparticles do not affect the PS glass transition temperature, which explains that the porous Si does not reduce the free volume for the polymer molecules to move. The polymer macromolecules just are adsorbed on the porous silicon surface, which partially limits their mobility.

Новый катодный материал La2/3Cu3Ti4−xFex O12−δ для твердооксидного топливного элемента: синтез и электропроводность

Copper lanthanum titanate La2/3Cu3Ti4−xFexO12−δ x = 0–1 was doped with Fe3+ cations. The diagram of the dependence of the tolerance factor on the relative electronegativity of cations for all studied compositions was represented. It was shown that all the compositions exist in the region of existence of distorted perovskite. X-ray diffraction and X-ray phase analysis methods established the region of existence of solid solutions of La2/3Cu3Ti4−xFexO12−δ obtained by ceramic technology, which was 0 ⩽ x ⩽ 0.4. The temperature dependences of electrical conductivity for the compositions from the region of existence of solid solutions La2/3Cu3Ti4−xFexO12−δ were obtained. The ionic-electronic nature of conductivity was suggested. It was shown that the decrease of electronic conductivity under the increase of iron content was due to the compensation of electronic carriers formed during acceptor doping.

Effects of ultrasonic vibration on residual stress distribution and local mechanical properties of AA6061/Ti6Al4V dissimilar joints by resistance spot welding

The joining of dissimilar titanium and aluminum alloys has potential applications in railway and aerospace industries, owing to substantial weight reduction and better economic viability. In this study, the residual stress distribution and local mechanical performance of ultrasonic-assisted resistance spot welding (UaRSW) welds were investigated. The welding current, welding time, and electrode force of the RSW process were set as 9.0 kA, 350 ms, and 1.0 kN respectively, and the frequency and power of ultrasonic vibration were 20 kHz and 800 W. The residual stress was evaluated by X-ray diffraction (XRD) method and numerical simulation, and these methods showed a reasonable match. There was tensile residual stress distributed on RSW welds and UaRSW welds, but the value of residual stress was reduced by about 30% at welding nugget and 20% at heat affected zone (HAZ) with the ultrasonic vibration, the reduction of residual stress in UaRSW welds was attributed to the more uniform temperature distribution and lower plastic deformation resistant of AA6061. The welding peak temperature was decreased from 1673.4 °C to 1584.2 °C with the ultrasonic vibration, resulted from the modified Al/Ti contact surface and reduced contact resistance. The miniature tensile test results showed the improvement of mechanical performance by ultrasonic vibration. The maximum load of welding nugget region increased from 19.6 N to 22.3 N, and the elongation obtained 10% increase. This hybrid welding technique shows a potential to improve the quality of welds with ensured efficiency, which is also simple to realize automation in the manufacturing industry.

Cross-rolling induced texture randomization and structural evolution for improved plastic isotropy in Al-Mg alloys with high Mg content

Plastic anisotropy is a key factor that affects the formability and performance of Al-Mg alloys. In this study, the effects of Mg content and strain path shifting from unidirectional rolling (UDR) to cross rolling processes (CR) on plastic anisotropy in Al-Mg alloys were investigated. Al-6 and 9Mg alloys were heat-treated and rolled in two different ways: the first was a UDR process, and the other was a CR process at room temperature. The rolled specimens were analyzed by electron backscattered diffraction method and tensile test. High Mg content suppresses the formation of texture that strengthens the plastic anisotropy in both UDR and CR processes. CR significantly reduces the rolling texture area fraction, leading to greater texture randomness compared to UDR. CR promotes the formation of low-angle deformation bands, which low-angle bands appear to have a weaker impact on deformation resistance and may contribute to the reduced anisotropy in CR-processed materials. CR results in a more uniform distribution of stored energy. R-value which represents plastic anisotropy decreases by shifting from UDR to CR, and by increment of Mg content. Overall, this study demonstrates that CR is a promising approach for improving the formability and performance of Al-Mg alloys by effectively controlling plastic anisotropy.

Yttrium iron garnet single-crystal particles - a simple and effective synthesis

Abstract Yttrium iron garnet (YIG) is a ferrimagnetic material which found applications in magnetics, electronics and optics. For those applications, a monocrystalline structure is often required. Although effective methods to grow large YIG single crystals exist, fabricating such structures in a powder form can be challenging. Here, we show a simple procedure to obtain large quantities of monocrystalline Y3Fe5O12 particles based on the precipitation synthesis. The average size of the single crystals was evaluated to be 149(6) nm. The morphology of the particles was analysed using SEM, TEM, DLS and nitrogen adsorption techniques. The material was tested for its structural properties with the use of XRD and electron diffraction methods. The chemical composition was investigated using FTIR, EDS and Raman spectroscopy. Finally, the thermal characteristics were analysed using TGA, while magnetic properties were tested with the use of the SQUID magnetometry. The obtained results are in good agreement with the theoretical values.

Gold Tripyrrindione: Redox Chemistry and Reactivity with Dichloromethane.

The identification of ligands that stabilize Au(III) centers has led to the isolation of complexes for applications in catalysis, gold-based therapeutics, and functional materials. Herein, we report the coordination of gold by tripyrrin-1,14-dione, a linear tripyrrole with the scaffold of naturally occurring metabolites of porphyrin-based protein cofactors (e.g., heme). Tripyrrindione H3TD2 binds Au(III) as a trianionic tridentate ligand to form square planar complex [Au(TD2)(H2O)], which features an adventitious aqua ligand. Two reversible ligand-based oxidations of this complex allow access to the other known redox states of the tripyrrindione framework. Conversely, (spectro)electrochemical measurements and DFT analysis indicate that the reduction of the complex is likely metal-based. The chemical reduction of [Au(TD2)(H2O)] leads to a reactive species that utilizes dichloromethane in the formation of a cyclometalated organo-Au(III) complex. Both the aqua and the organometallic Au(III) complexes were characterized in the solid state by microcrystal electron diffraction (MicroED) methods, which were critical for the analysis of the microcrystalline sample of the organo-gold species. Overall, this study illustrates the synthesis of Au(III) tripyrrindione as well as its redox profile and reactivity leading to gold alkylation chemistry.

Synthesis, crystal structure, spectroscopic, electronic and vibrational properties of N′-[(E)-3-pyridinylmethylene]nicotinohydrazide trihydrate: Experimental and computational study

N′-[(E)-3-pyridinylmethylene]nicotinohydrazide trihydrate (C12H10N4O·3(H2O)) was synthesized and its structure was determined by single crystal X-ray diffraction method. X-ray analysis showed that the compound crystalized in the triclinic system P-1 with a = 7.1134 (3) Å, b = 10.0208 (4) Å, c = 10.3601 (4) Å, α = 96.386 (3)°, β = 96.995 (3)°, γ = 101.219 (4)°, V = 712.05 (5) Å3 and Z = 2 and exhibits that the title compound (I) consists of N′-[(E)-3-pyridinylmethylene]nicotinohydrazide (II) (C12H10N4O), and three water molecules of crystallization. The two water molecules are attached to the third water molecule through intermolecular two OH…O hydrogen bonds. At the same time, this water molecule is linked to the NH amide group of the hydrazone by an intermolecular NH…O hydrogen bond. Hirshfeld surface (HS) analyses were carried out are to visualise the intermolecular interactions in the crystals of Compound I. The geometric optimization of the titled compound has been carried out by different computational methods such as by Hatree Fock (HF) and Density Functional Theory (DFT) methods with the 6–311++G (d,p) basis set. The vibrational frequency, dipole moment (μ), polarizability (α), hyperpolarizability (β), and electronic properties including the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO–LUMO) of the compound have been calculated at the level of both theories. In the results of crystal analysis and geometry calculations of the compound I, it was observed that intermolecular hydrogen bonds, N2H2A…O3, O3H31…O2 and O3H32…O4, were formed. The energy band gap (Eg = ELUMO-EHOMO) values were also obtained by using ELUMO and EHOMO at the level of both theories. The value of equilibrium (ground state) dipole moment of the studied molecule was calculated to be 8.31 Debye in B3LYP and 7.55 Debye in HF. The calculated hyperpolarizability values at the B3LYP/6–311++G(d,p) of the compound are 2.53 × 10−30 esu and this value corresponds to 6.79 times the hyperpolarizability value of urea.

Design and fabrication of a novel platform for detection of 5-fluorouracil as the anti-cancer drug using COFs/MOFs nanocomposite with graphene quantum dots

In this study, a novel modified electrode based on the covalent organic frameworks (COFs) Schiff base network-1 (SNW-1) hybridized with copper-based metal–organic frameworks (Cu-MOFs) embedded by graphene quantum dots (GQDs) nanocomposite at the glassy carbon electrode, SNW-1/Cu-MOFs/GQDs/GCE, was reported. The purpose of this modification is to enhance the detection capabilities of the constructed modified electrode for the 5-Fluorouracil (5-FU), an anti-cancer drug, by increasing its electrocatalytic activity towards the oxidation of 5-FU molecules. The SNW-1/Cu-MOFs/GQDs nanocomposite was effectively characterized by the various physicochemical analyses techniques including field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, tunneling electron microscopy, Brunauer-Emmett-Teller (BET), X-ray powder diffraction and electrochemical methods. Electrochemical studies showed that the modified electrode, SNW-1/Cu-MOFs/GQDs/GCE, has better electrocatalytic performance for oxidizing of the 5-FU compared to the unmodified GCE, GQDs/GCE, SNW-1/GCE, Cu-MOFs/GCE and SNW-1/Cu-MOFs/GCE. This enhancement can be attributed to large surface area, good electrical conductivity, enhanced electron transport capability of the SNW-1/Cu-MOFs/GQDs and also synergistic effect of the SNW-1/Cu-MOFs with GQDs. In optimized conditions, the SNW-1/Cu-MOFs/GQDs/GCE sensor demonstrates excellent properties including a wide linear response ranges (0.01–32 and 32–65 μM), low detection limit (35 nM), high sensitivity (3.8 μAμM-1cm2), long-term signal stability, and reproducibility. It is worth noting that this sensor can accurately determine 5-FU in biological sample, showcasing its potential for practical analysis.

Влияние технологических параметров на микроструктуру и свойства сплава AlSiMg, полученного методом селективного лазерного плавления

Introduction. The development of additive technologies is aimed at the synthesis of new powder compositions for selective laser melting plants, the study of the effect of mode parameters on the stable quality of products. The purpose of this work is to study the effect of the scanning strategy on the microstructure, elemental composition, porosity and density of specimens obtained by selective laser melting from non-spherical powders (Al — 91 wt. %, Si — 8 wt. %, Mg — 1 wt. %), subjected to special preparation to determine the optimal conditions for selective laser melting. The research methods are methods of X-ray diffraction and X-ray phase analysis, transmission electron microscopy. The paper examines specimens formed using four different scanning strategies. Results and discussions. A promising aluminum alloy AlSi8Mg is developed for selective laser melting. The material has good manufacturability and low powder cost. The technological parameters of melting make it possible to form a thin structure with a low level of porosity. The mechanism of influence of the scanning strategy on porosity, surface morphology, relative density and microstructure is investigated. A specimen from the AlSi8Mg powder composition with a high relative density of 99.97 % is produced by selective laser melting with an energy density of 200 J/mm3, a specimen scanning circuit when the direction of laser movement changes by an angle of 90° each odd layer. It is proved that the density of the AlSiMg alloy depends on the scanning strategy used. The calculated density of the specimen was 2.5 g/cm3, which corresponds to the density of silumin. Analysis of SEM images and maps of the distribution of elements (Al, Mg, Si) of the specimens showed that different specimen formation strategies do not affect the nature of silicon distribution. A unique grain structure is observed in the resulting AlSi8Mg alloy. The melt pool consists of small grains along the border and large grains in the center. The formation of fine grains is explained by the addition of Si and the high cooling rate during selective laser melting.

Tetraaza macrocyclic complexes of Cu(II), Co(III) and Ni(II) derived from template condensation of 2,6-pyridinedicarbohydrazide and 2,6-diacetylpyridine: Stability investigation and coloring properties on plastics

Completely conjugated 14-membered ring hexaaza ligand complexes of Cu(II), Co(III) and Ni(II) were synthesized by the template cyclo-condensation reaction of 2,6-diacetylpyridine and 2,6-pyridinedicarbohydrazide: [Cu(HL)Cl]·1.35H2O (1), [Cu(HL)Br]·CH3OH (2), [Cu(L)(H2O)]·4H2O (3), [Co(HL)Cl2]·CH3OH (4), (H3O)[Co(H2L)Cl2][Co(HL)Cl2]Cl2·H2O (5), [Co(HL)(SCN)2]·CH3OH (6), [Ni(L)]·3H2O (7) and (H3O)[Ni(L)]Cl·H2O (8). The structure of all complexes derived from this novel diprotic macrocyclic ligand H2L (5,7-dimethyl-3,4,8,9-tetraaza-1,6(2,6)-dipyridinacyclodecaphane-4,7-diene-2,10-dione) were determined by single crystal X-ray diffraction method. The tetraaza 14-membered conjugated macrocycle is N4-tetracoordinated to metal, adopts an essentially planar configuration and forms four fused metallocycles rings, two five-membered and two six-membered chelates. The structures of the studied complexes reveal three isomers out of three possible: with a 5-6-5-6 order of alternation of metallocycles for 1–6, the 5-5-6-6 isomer in 8 and the coexistence of two different isomers with 5-5-6-6 and 6-6-5-5 alternation of metallocycles in 7. Based on the protonation state of the macrocyclic ligand, four forms of the ligand have been registered: bis-deprotonated L2− (compounds 3, 7 and 8), monodeprotonated HL− (1, 2 and 4), neutral H2L (5) and for compound 6 tautomeric (amide → imidic acid) HL− form. The organisation of crystal structures 1–8 depends on the nature of the metal and the composition of the solvents and outer-sphere ions, but shows clear common features for the same type of metal. The hydrolytic study demonstrated a high stability of the Co(III) and Ni(II) complexes in acidic solutions and the most thermally stable are the complexes 3 and 7 with the limit of 350 °C for Ni(II) complex. Testing of the coloring properties of the [Ni(L)] (8) complex on plastics indicates a high coloring efficiency, especially for polyamide polymers.

Navigation through high-dimensional chemical space: discovery of Ba5Y13[SiO4]8O8.5 and Ba3Y2[Si2O7]2.

Two compounds were discovered in the well-studied BaO-Y2O3-SiO2 phase field. Two different experimental routines were used for the exploration of this system due to the differences of synthetic conditions and competition with a glass field. The first phase Ba5Y13[SiO4]8O8.5 was isolated through a combination of energy dispersive X-ray spectroscopy analysis and diffraction techniques which guided the exploration. The second phase Ba3Y2[Si2O7]2 was located using iterative algorithmic identification of target compositions. The structure solution of the new compounds was aided by continuous rotation electron diffraction, and the structures were refined against combined synchrotron and neutron time-of-flight powder diffraction. Ba5Y13[SiO4]8O8.5 crystallizes in I4̄2m, a = 18.92732(1), c = 5.357307(6) Å and represents its own structure type which combines elements of structures of known silicates embedded in columns of interconnected yttrium-centred polyhedra characteristic of high-pressure phases. Ba3Y2[Si2O7]2 has P21 symmetry with a pseudo-tetragonal cell (a = 16.47640(4), b = 9.04150(5), c = 9.04114(7) Å, β = 90.0122(9)°) and is a direct superstructure of the Ca3BaBi[P2O7]2 structure. Despite the lower symmetry, the structure of Ba3Y2[Si2O7]2 retains disorder in both Ba/Y sites and disilicate network, thus presenting a superposition of possible locally-ordered fragments. Ba5Y13[SiO4]8O8.5 has low thermal conductivity of 1.04(5) W m-1 K-1 at room temperature. The two discovered phases provide a rich structural platform for further functional material design. The interplay of automated unknown phase composition identification with multiple diffraction methods offers acceleration of the time-consuming exploration of high-dimensional chemical spaces for new structures.

Topochemical Polymerization at Diacetylene Metal-Organic Framework Thin Films for Tuning Nonlinear Optics.

Developing the topochemical polymerization of metal-organic frameworks (MOFs) is of pronounced significance for expanding their functionalities but is still a challenge on third-order nonlinear optics (NLO). Here, we report diacetylene MOF (CAS-1-3) films prepared using a stepwise deposition method and film structural transformation approach, featuring dynamic structural diversity. The MOF structures were determined by the three-dimensional electron diffraction (3D ED) method from nanocrystals collected from the films, which provides a reliable strategy for determining the precise structure of unknown MOF films. We demonstrate the well-aligned diacetylene groups in the MOFs can promote topological polymerization to produce a highly conjugated system under thermal stimulation. As a result, the three MOF films have distinct NLO properties: the CAS-1 film exhibits saturable absorption (SA) while CAS-2 and CAS-3 films exhibit reverse saturable absorption (RSA). Interestingly, due to the topochemical polymerization of the MOF films, a transition from SA to RSA response was observed with increasing temperatures, and the optical limiting effect was significantly enhanced (∼46 times). This study provides a new strategy for preparing NLO materials and thermally regulation of nonlinear optics.

Development of cement slurries with additives of nanoclay particles for the construction of oil wells at elevated temperatures

Relevance. Strength decrease is a phenomenon that becomes more pronounced as the temperature rises above 110°C. It is characterized by significant chemical and microstructural changes that Portland cement undergoes at high temperatures. Adding silica particles (SiO2) to cement can significantly increase cement resistance to strength reduction when the temperature exceeds 110°C. Nanoclays are currently used in the cement industry to increase the strength of the cement matrix due to their ability to fill capillary micropores and due to their relatively small particle size. Aim. To investigate the effect of adding nanoparticles (nanoclay) to Saudi grade G cement on compressive and tensile strength, and cement stone permeability under high temperature conditions (300°С). Objects. Six samples of cement mortars with different concentrations of nanoclay, cement stones from, tested after 7 and 28 days of hardening at 25 and 300°C. Methods. Cement chemical composition was evaluated by the X-ray fluorescence method with the WORKSTN-V Olympus Vanta X-ray fluorescence analyzer. Cement physical composition was evaluated by the method of ray diffraction on the Mastersizer 2000 laser particle size analyzer. The test of the grouting stone samples was carried out in accordance with ISO 10426-2:2003 on a hydraulic press 65-L1132. The tensile strength of the samples by the Brazilian method was tested in accordance with ASTM D 3967-08 standard on a hydraulic press 65-L1132. The permeability of the samples was determined by single-phase stationary filtration at a facility for studying the filtration and capacitance properties of the PIK-OFP-UCH core in accordance with ISO 10426-2:2003. Results. The data obtained showed that cement destruction at extremely high temperatures can be avoided by using nanoclay (up to 3% by weight of cement). The microstructure of the cement matrix was significantly affected due to the aggregation of nanoparticles when more than 3% of nanoclay was added. All rheological characteristics of the cement slurry were improved by the addition of nanoclay particles.

Investigating the Role of Microclimate and Microorganisms in the Deterioration of Stone Heritage: The Case of Rupestrian Church from Jac, Romania

Natural stone can undergo disaggregation from various causes, including physical actions such as freeze–thaw cycles, temperature and humidity variations, chemical actions such as the solubilization of minerals by organic and inorganic acids, as well as biological actions due to the colonization of organisms that can produce biocorrosion and biomineralization. This research investigates the impact of microclimatic conditions and microbial activity on the physical and chemical integrity of stone heritage, particularly the biodeterioration caused by fungi in the case of a Romanian rock church. Various analytical techniques were employed, including macroscopic and optical microscopy, Raman spectroscopy, X-ray diffraction, and culture-based identification methods, to characterize the mineral composition and microbial contamination of the rock samples. The analyses revealed that the sandstone consists primarily of quartz (over 90%), muscovite (5–10%), and feldspars. The identified fungi included Cladosporium herbarium, Aspergillus niger, and Mortierella hyalina. The SEM images showed fungal hyphae and spores within the kaolinite–illite matrix, indicating significant microbial colonization and its role in rock deterioration. Additionally, microclimatic data collected over a 12-week period highlighted the substantial fluctuations in temperature and relative humidity within the church, which contribute to the physical and chemical weathering of the stone. This study also noted high levels of particulate matter (PM2.5 and PM10) and volatile organic compounds, which can exacerbate microbial growth and stone decay. The comprehensive analysis underscores the need for targeted preservation strategies that consider both microclimatic factors and microbial colonization to effectively conserve stone heritage sites, ensuring their longevity and structural integrity.

Corrosion of Chromium Coating Fabricated on Zircaloy-4 Substrate.

In the nuclear industry, coated cladding is a topical problem and it is chosen as the near-term and most promising ATF (Accident-Tolerant Fuel) cladding concept. The main objective of this concept is to enhance the accident tolerance of nuclear power plants and accordingly, the performance of cladding is expected to be improved. This work assesses the corrosion performance of a Zircalloy-4 alloy coated with a thin chromium coating by MS (magnetron sputtering), tested under a CANDU (CANada Deuterium Uranium) reactor primary circuit simulated condition (LiOH solution, 10 MPa, 310 °C, pH = 10.5). The anticorrosive performance is evaluated by a gravimetric analysis, a metallographic analysis, X-ray diffraction, electronic microscopy, and electrochemical methods. A four times less gain mass was noticed compared to uncoated Zircaloy-4, indicating a smaller corrosion rate. The SEM micrographs illustrate that the coatings are still adherent, and they are keeping the initial morphological characteristics during the autoclaving process. A SEM cross-section analysis shows values of the thickness of the coatings between 0.8 and 1.46 µm. By XRD, the presence of Cr2O3 oxide is identified. Electrochemical testing confirms good stability and good corrosion performance of Cr coating over time under autoclave conditions.

Electrocatalytic efficiency of carbon nitride supported gold nanoparticle based sensor for iodide and cysteine detection

Extensive investigations are being conducted on gold nanoparticles focusing on their applications in biosensors, laser phototherapy, targeted drug delivery and bioimaging utilizing advanced detection techniques. In this work, an electrochemical sensor was developed based on graphite carbon nitride supported gold nanoparticles. Carbon nitride supported gold nanoparticles (Au–CN) was synthesized by applying a deposition-precipitation route followed by a chemical reduction technique. The composite system was characterized by X-ray diffraction and X-ray photo electron spectroscopy methods. Electron microscopy analysis confirmed the formation of gold nanoparticles within the size range of 5–15 nm on the carbon nitride support. Carbon nitride supported gold based sensor was employed for the electrochemical detection of iodide ion and l-cysteine. The limit of detection and sensitivity of the sensor was attained 8.9 μM and 0.96 μAμM⁻1cm⁻2, respectively, for iodide ion, while 0.48 μM and 5.8 μAμM⁻1cm⁻2, respectively, was achieved for the recognition of cysteine. Furthermore, a paper-based electrochemical device was developed using the Au–CN hybrid system that exhibited promising results in detecting iodide ions, highlighting its potential for economic and portable device applications.

Selecting a target for obtaining films of higher manganese silicide using magnetron sputtering

A film of manganese silicides on mica was obtained using a magnetron sputter from three types of targets. Microstructure and elemental composition of targets and films studied by scanning electron microscopy and electron reflection diffraction methods. The phase composition and texture of films by thickness (cross sections) were controlled by scanning and transmission electron microscopy. It has been shown that when depositing films from a poly- and single-crystalline target of higher manganese silicide, in contrast to a target of sintered Mn and Si powders, after successive annealing at a temperature of 800 K and a temperature of 10–3 Pa for 1 hour, polycrystalline films of higher silicide can be obtained. manganese composition Mn4Si7.