Search Results (102)

To improve the performance of superhard ceramic composites, this study aims to develop a dense, phase-pure, and uniform TiN coating on cubic boron nitride (cBN) particles with a target thickness of at least 150 nm. TiN coatings were applied using atomic layer deposition (ALD) alone, as well as a combined ALD/chemical vapor deposition (CVD) process. While ALD produced uniform and dense coatings, the thickness remained below 50 nm. The combined ALD/CVD approach achieved greater thicknesses up to 500 nm, though coating homogeneity remained a challenge. Optimization efforts, including increased ALD cycles and reduced CVD pressure, led to improved coating uniformity, with 25%–30% of particles coated to thicknesses ≥ 80 nm. Structural analysis confirmed dense, pore-free TiN_1−x layers for all synthesized powders. In contrast, the commercial reference powder showed a non-uniform, multiphase coating (α − Ti, Ti₂N, and TiN_0.53) with defects. While the ALD/CVD powders exhibited better phase purity than the commercial sample, further optimization is needed to achieve consistent coatings above 150 nm. These results suggest the ALD/CVD route is promising for producing coatings suitable for use in ceramic matrix composites. Full article

(1) Background: Generation IV supercritical water-cooled reactors (SCWRs), including small modular reactor (SCW-SMR) variants, are pivotal in nuclear technology. Operating at 300–500 °C and 25 MPa, these reactors require detailed understanding of radiation chemistry and transient species to optimize water chemistry, reduce corrosion, and enhance safety. Boron, widely used as a neutron absorber, plays a significant role in reactor performance and safety. This study focuses on the yields of radiolytic species in subcritical and supercritical water exposed to ⁴He and ⁷Li recoil ions from the ¹⁰B(n,α)⁷Li fission reaction in SCWR/SCW-SMR environments. (2) Methods: We use Monte Carlo track chemistry simulations to calculate yields (G values) of primary radicals (e⁻_aq, H^•, and ^•OH) and molecular species (H₂ and H₂O₂) from water radiolysis by α-particles and Li³⁺ recoils across 1 picosecond to 0.1 millisecond timescales. (3) Results: Simulations show substantially lower radical yields, notably e⁻_aq and ^•OH, alongside higher molecular product yields compared to low linear energy transfer (LET) radiation, underscoring the high-LET nature of ¹⁰B(n,α)⁷Li recoil nuclei. Key changes include elevated G(^•OH) and G(H₂), and a decrease in G(H^•), primarily driven during the homogeneous chemical stage of radiolysis by the reaction H^• + H₂O → ^•OH + H₂. This reaction significantly contributes to H₂ production, potentially reducing the need for added hydrogen in coolant water to mitigate oxidizing species. In supercritical conditions, low G(H₂O₂) suggests that H₂O₂ is unlikely to be a major contributor to material oxidation. (4) Conclusions: The ¹⁰B(n,α)⁷Li reaction’s yield estimates could significantly impact coolant chemistry strategies in SCWRs and SCW-SMRs. Understanding radiolytic behavior in these conditions aids in refining reactor models and coolant chemistry to minimize corrosion and radiolytic damage. Future experiments are needed to validate these predictions. Full article

This study elucidates the dynamic tribo-mechanical response of laser-cladded FeNiCr-B₄C metal matrix composite (MMC) coatings on AISI 1040 steel substrate, unraveling the intricate interplay between microstructural features and phase transformations. A multi-faceted approach, employing high-resolution scanning electron microscopy (SEM) and advanced X-ray diffraction/Raman spectroscopy techniques, provided a comprehensive characterization of the coatings’ behavior under mechanical and scratch testing, shedding light on the mechanisms governing their wear resistance. Specifically, microstructural analysis revealed uniform coatings with a columnar structure and controlled defect density, showcasing an average thickness of 250 ± 20 μm and a transition zone of 80 ± 10 μm. X-ray diffraction and Raman spectroscopy confirmed the presence of α-Fe (Im-3m), γ-FeNiCr (Fm-3m), Fe₂B (I-42m), and B₄C (R-3m) phases, highlighting the successful incorporation of B₄C reinforcement. The addition of 5 and 7 wt.% B₄C significantly increased microhardness, showing enhancements up to 201% compared to the B₄C-free FeNiCr coating and up to 351% relative to the AISI 1040 steel substrate, respectively. Boron carbide addition promoted a synergistic strengthening effect between the in situ formed Fe₂B and the retained B₄C phases. Furthermore, scratch test analysis clarified improved wear resistance, excellent adhesion, and a tailored hardness gradient. These findings demonstrated that optimized short-pulsed laser cladding, combined with moderate B₄C reinforcement, is a promising route for creating robust, high-strength FeNiCr-B₄C MMC coatings suitable for demanding engineering applications. Full article

Mogroside V crude extract from Siraitia grosvenorii has many pharmacological effects, such as anti-diabetes, antioxidant, etc. It is being used as a kind of natural sweetener in more and more countries. The improvement of Mogroside V purity can greatly promote the utilization value of Siraitia grosvenorii and the quality of related products. For this paper, a boronic acid-functionalized silica gel adsorbent (SiO₂-GP-APBA) was synthesized and applied for the first time in the purification of mogroside V from the crude extract of Siraitia grosvenorii. It was demonstrated that it was 30–100 μm with 163.1 μmol/g of boronic acid groups on the surface of silica gel and stable at below 380.20 °C. Its maximum adsorption capacity to mogroside V was up to 206.74 mg/g at room temperature. After the saturated absorption from the crude extract of Siraitia grosvenorii in a pH 3 solution, 96.36% mogroside V could be released from SiO₂-GP-APBA using a pH 7 aqueous solution, which was better than ethanol. The purity of mogroside V was significantly increased from 35.67% to 76.34%. Semi-preparative HPLC could further improve the purity of mogroside V to 99.60%. Additionally, the direct inhibition effect of the mogroside V on α-glucosidase was determined for the first time. Its inhibitory constant was 46.11 μM, indicating mogroside V was beneficial for the treatment of diabetes. Full article

Macrotermes barneyi is a typical fungus-growing termite that forms both monogynous (single queen) and polygynous (multiple queen) colonies in nature. This species influences the local soil fertility in part by redistributing nutrients across the landscape in its habitats. However, how the colony structure of M. barneyi affects nutrient cycling and microbial communities within the nest is not well understood. In this study, we compared the physicochemical properties and microbial communities across nest parts between monogynous and polygynous colonies of M. barneyi. Our results showed that the fungus garden is the most nutrient-rich part of the nest, with higher soil moisture, organic matter, ammonium nitrogen, nitrate nitrogen, available sulfur, available potassium, available silicon, and available boron than other nest parts. Notably, the fungus garden in monogynous colonies had higher nitrate nitrogen, available sulfur, and available silicon than those in the polygynous colonies. The microbial α-diversity in the fungus garden was lower than that in other parts of the nest. β-diversity analysis revealed a clear separation of microbial communities between monogynous and polygynous colonies across nest parts. Furthermore, the relative abundance of functional genes associated with “cell cycle control, cell division, and chromosome partitioning” was higher in the fungus garden of polygynous colonies compared to monogynous colonies. Our results suggest that the fungus garden plays a crucial role in maintaining colony stability in M. barneyi colonies. The rapid depletion of nutrients in the fungus garden to sustain the larger population in polygynous colonies likely influences microbial community dynamics and nutrient cycling. Full article

Estrogens in aquatic environments pose significant ecological and health risks due to their cumulative effects rather than individual impacts. This study investigates the voltammetric behavior of estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2), presenting a cost-effective and straightforward method for their simultaneous determination. Using differential pulse voltammetry (DPV) with a boron-doped diamond electrode, the method demonstrates high precision (deviations under 4%) and a linear dynamic range of 15.35–134.55 µmol·L⁻¹. Integration of a vacuum evaporation step reduced detection limits to 10⁻⁸ mol·L⁻¹, enabling effective analysis of real water samples. This optimized approach ensures practical applicability for monitoring total estrogen content in aquatic systems, providing an accessible and reliable alternative to conventional methods. Full article

Background: Boron neutron capture therapy (BNCT) is an innovative binary form of radiation therapy with high selectivity towards cancer tissue based on the neutron capture reaction ¹⁰B(n,$\alpha$)⁷Li, consisting in the exposition of patients to neutron beams after administration of a boron compound with preferential accumulation in cancer cells. The high linear energy transfer products of the ensuing reaction deposit their energy at the cell level, sparing normal tissue. Although progress in accelerator-based BNCT has led to renewed interest in this cancer treatment modality, in vivo dose monitoring during treatment still remains not feasible and several approaches are under investigation. While Compton imaging presents various advantages over other imaging methods, it typically requires long reconstruction times, comparable with BNCT treatment duration. Methods: This study aims to develop deep neural network models to estimate the dose distribution by using a simulated dataset of BNCT Compton camera images. The models pursue the avoidance of the iteration time associated with the maximum-likelihood expectation-maximization algorithm (MLEM), enabling a prompt dose reconstruction during the treatment. The U-Net architecture and two variants based on the deep convolutional framelets framework have been used for noise and artifact reduction in few-iteration reconstructed images. Results: This approach has led to promising results in terms of reconstruction accuracy and processing time, with a reduction by a factor of about 6 with respect to classical iterative algorithms. Conclusions: This can be considered a good reconstruction time performance, considering typical BNCT treatment times. Further enhancements may be achieved by optimizing the reconstruction of input images with different deep learning techniques. Full article

In this work, a series of boronated amidines based on the closo-dodecaborate anion and amino acids containing an amino group in the side chain of the general formula [B₁₂H₁₁NHC(NH(CH₂)_nCH(NH₃)COOH)CH₃], where n = 2, 3, 4, were synthesized. These derivatives contain conserved α-amino and α-carboxyl groups recognized by the binding centers of the large neutral amino acid transporter (LAT) system, which serves as a target for the clinically applied BNCT agent para-boronophenylalanine (BPA). The paper describes several approaches to synthesizing the target compounds, their acute toxicity studies, and tumor uptake studies in vivo in two tumor models. The promising compound [B₁₂H₁₁NHC(NH(CH₂)₂CH(NH₃)COOH)CH₃]*3H₂O demonstrates low toxicity (LD₅₀ in a range from 150 to 300 mg/kg) and excellent solubility and also shows selective uptake in experimental melanoma in laboratory mice (T/N ratio remained >3 up to 60 min post-injection, with a maximum T/N of 6.2 ± 2.8 at 45 min). Full article

Drug leads with a high Fsp³ index are more likely to possess desirable properties for progression in the drug development pipeline. This paper describes the first detailed NMR analysis of the borylated intermediate 3-deoxy-3-boronodiethanolamine-1,2:5,6-di-O-isopropylidene-α-d-galactofuranose and of the corresponding free monosaccharide analogue 3-boronic-3-deoxy-d-galactose in the early stage of the concurrent equilibrium processes of mutarotation and borarotation. A discussion of all potential equilibria is also presented alongside a comparison with relevant ¹¹B-NMR data available from the scientific literature and our own library. Full article

Pyrazolo[3,4-b]pyridine scaffolds have been heavily exploited in the development of nitrogen-containing heterocycles with numerous therapeutic applications in the field of medicinal and pharmaceutical chemistry. The present work describes the synthesis of eighteen biaryl pyrazolo[3,4-b]pyridine ester (6a–i) and hydrazide (7a–i) derivatives via the Suzuki cross-coupling reaction. These derivatives were subsequently screened for their therapeutic potential to inhibit the diabetic α-amylase enzyme, which is a key facet of the development of anti-diabetic agents. Initially, the ethyl 4-(4-bromophenyl)-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]pyridine-6-carboxylate 4 was synthesized through a modified Doebner method under solvent-free conditions, providing an intermediate for further derivatization with a 60% yield. This intermediate 4 was subjected to Suzuki cross-coupling, reacting with electronically diverse aryl boronic acids to obtain the corresponding pyrazolo[3,4-b]pyridine ester derivatives (6a–i). Following this, the biaryl ester derivatives (6a–i) were converted into hydrazide derivatives (7a–i) through a straightforward reaction with hydrazine monohydrate and were characterized using ¹H-NMR, ¹³C-NMR, and LC-MS spectroscopic techniques. These derivatives were screened for their α-amylase inhibitory chemotherapeutic efficacy, and most of the biaryl ester and hydrazide derivatives demonstrated promising amylase inhibition. In the (6a–i) series, the compounds 6b, 6c, 6h, and 6g exhibited excellent inhibition, with almost similar IC₅₀ values of 5.14, 5.15, 5.56, and 5.20 μM, respectively. Similarly, in the series (7a–i), the derivatives 7a, 7b, 7c, 7d, 7f, 7g, and 7h displayed excellent anti-diabetic activities of 5.21, 5.18, 5.17, 5.12, 5.10, 5.16, and 5.19 μM, respectively. These in vitro results were compared with the reference drug acarbose (IC₅₀ = 200.1 ± 0.15 μM), demonstrating better anti-diabetic inhibitory activity in comparison to the reference drug. The in silico molecular docking study results were consistent with the experimental biological findings, thereby supporting the in vitro pharmaceutical efficacy of the synthesized derivatives. Full article

Pack boriding with CeO₂ was performed on the powder metallurgical (PM) near-α type titanium alloy at a temperature of 1273–1373 K for 5–15 h followed by air cooling. The microstructure analysis showed that the boride layer on the surface of the alloy was mainly composed of a monolithic TiB₂ outer layer, inner whisker TiB and sub-micron sized flake-like TiB layer. The growth kinetics of the TiB₂ and TiB layers obeyed the parabolic diffusion model. The diffusion coefficient of boron in the boride layers obtained in the present study was well within the ranges reported in the literature. The activation energies of boron in the TiB₂ and TiB layers during the pack boriding were estimated to be 166.4 kJ/mol and 122.8 kJ/mol, respectively. Friction tests showed that alloys borided at moderate temperatures and times had lower friction coefficients, which may have been due to the fine grain strengthening effect of TiB whiskers. The alloy borided at 1273 K for 10 h had a minimum friction coefficient of 0.73. Full article

The fluid pump was the key component of the formation tester; the pump cylinder, piston, and piston rod of the fluid pump often suffer from wear scratches and seal failure, which greatly reduces the service reliability of the instrument. To improve the wear resistance of the fluid pump, 17-4PH steel specimens were treated by boronizing at 750 °C for 20 h. Specimens with and without boronizing were studied by OM, SEM, XRD, microhardness test, and wear resistance test. Layers of about 60 μm thickness formed during boronization contain a mixture of FeB, CrB, and α(B)-Fe phases, which leads to a significant improvement in microhardness (from 336 to 980 HV) and wear rate (from 16.4 × 10⁻⁵ mm³/Nm to 3.3 × 10⁻⁵ mm³/Nm). The pump cylinder and the fluid-pump piston rod were boronized and assembled into the pumping module, which passed the indoor durability test for 90 h and did not show obvious surface wear after 60 h of field experience. For the first time, the boronization process extends the service time of the fluid pump, improving the wear resistance of the pump cylinder and piston rod. Full article

Ficus drupacea is a fruit-bearing tree that is distributed in Southeast Asia and Australia. The objective of this research was to ascertain the following with regard to ripened fruits: (i) their nutritional value, (ii) their mineral status, (iii) the fatty acid composition of fruit and seed oil, (iv) their phytochemical makeup, and (v) their antioxidant properties. The ripened fruits contained 3.21%, 3.25%, 0.92%, 1.47%, and 2.20% carbohydrate, protein, fat, ash, and fiber, respectively. Fruits had an energy content of 30.18 kcal/100 g. In terms of mineral content, the fruit was rich in potassium, magnesium, calcium, and nitrogen, with values of 21.03, 13.24, 11.07, and 4.13 mg/g DW. Iron, zinc, manganese, and boron had values of 686.67, 124.33, 114.40, and 35.78 µg/g DW, respectively. The contents of oxalate and phytate were 14.44 and 2.8 mg/g FW, respectively. The fruit and seed oil content were 0.67 and 8.07%, respectively, and the oil’s physicochemical properties were comparable to those of fig fruit and seed oils. Omega-3 (α-linolenic acid), omega-6 (linoleic acid), and omega-9 (oleic acid) fatty acids were abundant in the oils. Fruit extracts in acetone, methanol, and water have greater concentrations of phenolics, flavonoids, and alkaloids. The 2,2-diphenyl-2-picrylhydrazyl, total antioxidant activity, and ferric reducing antioxidant power assays demonstrated increased antioxidant activities in close correlation with the higher concentrations of phenolics, flavonoids, and alkaloids. The results of this study demonstrate that the fruits of F. drupacea are a strong source of nutrients and phytochemicals, and they merit more investigation and thought for possible uses. Full article

This review article is focused on the progress made in the synthesis of 5′-α-P-modified nucleoside triphosphates (α-phosphate mimetics). A variety of α-P-modified nucleoside triphosphates (NTPαXYs, Y = O, S; X = S, Se, BH₃, alkyl, amine, N-alkyl, imido, or others) have been developed. There is a unique class of nucleoside triphosphate analogs with different properties. The main chemical approaches to the synthesis of NTPαXYs are analyzed and systematized here. Using the data presented here on the diversity of NTPαXYs and their synthesis protocols, it is possible to select an appropriate method for obtaining a desired α-phosphate mimetic. Triphosphates’ substrate properties toward nucleic acid metabolism enzymes are highlighted too. We reviewed some of the most prominent applications of NTPαXYs including the use of modified dNTPs in studies on mechanisms of action of polymerases or in systematic evolution of ligands by exponential enrichment (SELEX). The presence of heteroatoms such as sulfur, selenium, or boron in α-phosphate makes modified triphosphates nuclease resistant. The most distinctive feature of NTPαXYs is that they can be recognized by polymerases. As a result, S-, Se-, or BH₃-modified phosphate residues can be incorporated into DNA or RNA. This property has made NTPαXYs a multifunctional tool in molecular biology. This review will be of interest to synthetic chemists, biochemists, biotechnologists, or biologists engaged in basic or applied research. Full article

We quantify the chemistry–process–structure–property relationships of a Ti-6Al-4V alloy in which titanium-boron alloy (Ti-B) was added in a functionally graded assembly through a laser-engineered net shaping (LENS) process. The material gradient was made by pre-alloyed powder additions to form an in situ melt of the prescribed alloy concentration. The complex heterogeneous structures arising from the LENS thermal history are completely discussed for the first time, and we introduce a new term called “Borlite”, a eutectic structure containing orthorhombic titanium monoboride (TiB) and titanium. The β-titanium grain size decreased nonlinearly until reaching the minimum when the boron weight fraction reached 0.25%. Similarly, the transformed α-titanium grain size decreased nonlinearly until reaching the minimum level, but the grain size was approximately 2 μm when the boron weight fraction reached 0.6%. Alternatively, the α-titanium grain size increased nonlinearly from 1 to 5 μm as a function of the aluminum concentration increasing from 0% to 6% aluminum by weight and vanadium increasing from 0% to 4% by weight. Finally, the cause–effect relationships related to the creation of unwanted porosity were quantified, which helps in further developing additively manufactured metal alloys. Full article