Search Results (855)

A series of half-titanocenes containing different trialkylsilyl para-phenoxy substituents, Cp*TiCl₂(O-2,6-ⁱPr₂-4-R-C₆H₂) [Cp* = C₅Me₅; R = Si(n-Bu)₃ (5), SiMe₂(n-C₈H₁₇) (6), SiMe₂(t-Bu) (7)], were prepared and identified. Catalytic activity in ethylene polymerization by Cp*TiCl₂(O-2,6-ⁱPr₂-4-R-C₆H₂) [R = H (1), SiMe₃ (2), SiEt₃ (3), Si(i-Pr)₃ (4), 5–7]–MAO (methylaluminoxane) catalysts increased in the following order (in toluene at 25 °C, ethylene 4 atm): R = H (1) < SiMe₃ (2), SiEt₃ (3), Si(i-Pr)₃ (4) < SiMe₂(t-Bu) (7) < SiMe₂(n-C₈H₁₇) (6) < Si(n-Bu)₃ (5, activity = 6.56 × 10⁴ kg-PE/mol-Ti·h). The results thus suggest that the introduction of an alkyl group into a silyl substituent led to an increase in activity. The activities of 5 were affected by the Al/Ti molar ratio (amount of MAO charged), and the highest activity (7.00 × 10⁵ kg-PE/mol-Ti·h) was observed under optimized conditions at 50 °C, whereas the activity decreased at 80 °C. In ethylene copolymerization with 1-dodecene, the Si(n-Bu)₃ analog (5) exhibited remarkable catalytic activity (4.32 × 10⁶ kg-polymer/mol-Ti·h at 25 °C), which was higher than those of the reported catalysts (1–3), affording poly(ethylene-co-1-dodecene)s with efficient comonomer incorporation as observed in 3 [r_E = 3.77 (5) vs. 3.58 (3)]. Full article

This work deals with the preparation of a novel set of ternary polymer composites, where the matrix is a cellulose ether and the reinforcement agent is a 50:50 mixture of TiO₂ nanoparticles with PbCl₂ micropowder (0.25–4 wt%). The attained film samples are investigated from morphological, optical, and electrical points of view to explore the applicative potential as LED encapsulants or flexible dielectric layers for capacitors. Morphological analyses at micro- and nanoscale evidence the level of distribution of the fillers blended within the matrix. UV-VIS spectroscopy and refractometry emphasize that at 0.5 wt% the samples display the best balance between transparency and high refractive index, which matches the applicative criteria for LED encapsulation. The electrical testing with broadband dielectric spectrometer proves that the dielectric constant at 1 kHz of the composite with 4 wt% fillers is enhanced by about 6.63 times in comparison to the neat polymer. This is beneficial for designing eco-friendly and flexible dielectrics for capacitor devices. Full article

This study presents an innovative iontophoretic delivery system for glycolic acid (GA) based on polysaccharide microbeads embedded within an electrolyte hydrogel. The mi-crobeads, fabricated using a peristaltic pump, exhibited a uniform morphology with an average diameter of 1078 ± 140.38 μm and were successfully integrated into a hydrogel matrix (thickness: 4542.55 ± 337.24 μm). Comprehensive physicochemical characterization (FT-IR, XRD, SEM) confirmed effective component integration. The hydrogel demonstrated optimal mechanical properties with a tensile strength of 0.02 ± 0.003 MPa and reliable adhesion to various substrates, while maintaining excellent self-healing capabili-ties—post-repair conductivity remained sufficient to power an LED indicator. The material demonstrated favorable conductivity under various storage conditions while maintaining non-cytotoxic properties. Notably, microbead incorporation preserved electrochemical performance, as demonstrated by stable behavior in cyclic voltammetry using an Ag/AgCl reference system. Iontophoretic testing revealed significantly enhanced glycolic acid delivery at −1.0 V com-pared to passive diffusion. The system, combining PVA, PAA, alginate, [Bmim]BF₄, and E. prolifera polysaccharides with gellan gum, shows strong potential for advanced cosmetic dermatology applications requiring precise active ingredient delivery. Full article

A hierarchical photoanode composed of amorphous indium phosphate (InPO_x)-coated titanium dioxide nanowires (TiO₂ NWs) was successfully fabricated via a hydrothermal method followed by dip-coating and thermal phosphidation. Structural characterization revealed the formation of a uniform InPO_x shell on the surface of vertically aligned TiO₂ NWs, without altering their 1D morphology. X-ray photoelectron spectroscopy confirmed the incorporation of phosphate species and the presence of oxygen vacancies, which contribute to enhanced interfacial charge dynamics. Photoelectrochemical (PEC) measurements demonstrated that the InPO_x/TiO₂ NWs significantly improved photocurrent density, with the 0.1 M InCl₃-derived sample achieving 0.36 mA·cm⁻² at 1.0 V—an enhancement of approximately 928% over pristine TiO₂. This enhancement is attributed to improved charge separation and injection efficiency (91%), as well as reduced interfacial resistance verified by electrochemical impedance spectroscopy. Moreover, the Mott–Schottky analysis indicated a four-order increase in carrier density due to the InPO_x shell. The modified electrode also exhibited superior stability under continuous illumination for 3 h. These findings highlight the potential of amorphous InPO_x as an effective cocatalyst for constructing efficient and durable TiO₂-based photoanodes for solar-driven water-splitting applications. Full article

Linear Low-Density Polyethylene (LLDPE) is a versatile polyolefin made by copolymerizing ethene with minor amounts of a 1-alkene. The short side chain branches in the comonomer units partly hinder the ability of the polyethylene main chain to crystallize, thus providing a way to fine-tune material properties between the extremes of a thermoplastic and a moderate elastomer. In this function, higher 1-alkenes such as 1-hexene or 1-octene are more effective than shorter homologs like propene or 1-butene, because their alkyl substituents are fully incompatible with the polyethylene lattice. On the other hand, the former comonomers are also more expensive and, above all, poorly reactive with heterogeneous Ziegler–Natta (ZN) catalysts, the workhorses of the polyolefin industry; as a matter of fact, they can only be used with technologically more demanding molecular catalysts. The molecular kinetic factors governing this important and complicated catalytic reactivity are still poorly understood, and perusal of the literature led us to conclude that data reliability is often questionable due to experimental limitations in reaction equipment and protocols, particularly in academic laboratories. In this study, we made use of a state-of-the-art High-Throughput Experimentation workflow to measure the reactivity ratios with ethene of two representative higher 1-alkenes, namely 1-hexene and 1-decene, in the presence of a variety of well-defined molecular catalysts of metallocene and post-metallocene nature comparatively with a typical MgCl₂/TiCl₄ ZN catalyst for polyethylene application. We found that the two comonomers react almost identically with molecular catalysts, whereas a major decrease in reactivity for 1-decene compared with 1-hexene was observed idiosyncratically for the ZN catalyst. In our opinion, the overall results suggest that in the latter case, surface effects can be dominant over direct comonomer interactions with the coordination sphere of the active metal in dictating the observed molecular kinetic behavior. Full article

Soil salinity severely impairs plant growth, and polyamines such as spermidine (Spd) are known to bolster stress tolerance by acting as osmoprotectants and signaling molecules. Using TiO₂ enrichment, iTRAQ quantification, and bioinformatics analysis, we identified 870 proteins and 157 differentially phosphorylated proteins. Functional annotation showed that salt stress activated key components of the Salt Overly Sensitive pathway, particularly serine threonine kinases (SOS2) and Ca²⁺ binding sensors (SOS3). Among thirty-six SOS-associated kinases detected, eight SOS2 isoforms, four MAPKs, and two SOS3 homologs were significantly upregulated by NaCl, and Spd further increased the phosphorylation of six SOS2 proteins and one SOS3 protein under salt stress, with no detectable effect on SOS1. qRT PCR revealed enhanced expression of MAPKs and calcium-dependent protein kinases, suggesting a phosphorylation-centered model in which Spd amplifies Ca²⁺-mediated SOS signaling and reinforces ion homeostasis through coordinated transcriptional priming and post-translational control. Additional, proteins involved in protein synthesis and turnover (ribosomal subunits, translation initiation factors, ubiquitin–proteasome components), DNA replication and transcription, and RNA processing showed differential expression under salt or Spd treatment. Central metabolic pathways were reprogrammed, involving glycolysis, the TCA cycle, the pentose phosphate pathway, as well as ammonium transporters and amino acid biosynthetic enzymes. These findings indicate that exogenous Spd regulated phosphorylation-mediated networks involving the SOS signaling pathway, protein homeostasis, and metabolism, thereby enhancing cucumber salt tolerance. Full article

Perovskite solar cells (PSCs) have emerged as a promising contender in photovoltaics, owing to their rapidly advancing power conversion efficiencies (PCEs) and compatibility with low-temperature solution processing techniques. Single-junction architectures reveal inherent limitations imposed by the Shockley–Queisser (SQ) limit, motivating adoption of a dual-absorber structure comprising Cs₄CuSb₂Cl₁₂ (CCSC) and Cs₂TiI₆ (CTI)—lead-free perovskite derivatives valued for environmental benignity and intrinsic stability. Comprehensive theoretical screening of 26 electron/hole transport layer (ETL/HTL) candidates identified SrTiO₃ (STO) and CuSCN as optimal charge transport materials, producing an initial simulated PCE of 16.27%. Subsequent theoretical optimization of key parameters—including bulk and interface defect densities, band gap, layer thickness, and electrode materials—culminated in a simulated PCE of 30.86%. Incorporating quantifiable practical constraints, including radiative recombination, resistance, and FTO reflection, revised simulated efficiency to 26.60%, while qualitative analysis of additional factors follows later. Furthermore, comparing multiple algorithms within this theoretical framework demonstrated eXtreme Gradient Boosting (XGBoost) possesses superior predictive capability, identifying CTI defect density as the dominant impact on PCE—thereby underscoring its critical role in analogous architectures and offering optimization guidance for experimental studies. Collectively, this theoretical research delineates a viable pathway toward developing stable, environmentally sustainable PSCs with high properties. Full article

TiAl alloy offers advantages including low density, high specific strength and stiffness, and excellent high-temperature creep resistance. It is widely used in the aerospace, automotive, and chemical sectors, as well as in other fields. However, at temperatures of 800 °C and above, it forms a porous oxide film predominantly composed of TiO₂, which fails to provide adequate protection. Applying high-temperature protective coatings is therefore essential. Oxides demonstrating protective efficacy at elevated temperatures include Al₂O₃, Cr₂O₃, and SiO₂. The Pilling–Bedworth Ratio (PBR)—defined as the ratio of the volume of the oxide formed to the volume of the metal consumed—serves as a critical criterion for assessing oxide film integrity. A PBR value greater than 1 but less than 2 indicates superior film integrity and enhanced oxidation resistance. Among common oxides, Al₂O₃ exhibits a PBR value within this optimal range (1−2), rendering aluminum-based compound coatings the most extensively utilized. Aluminum coatings can be applied via methods such as pack cementation, thermal spraying, and hot-dip aluminizing. Pack cementation, being the simplest to operate, is widely employed. In this study, a powder mixture with the composition Al:Al₂O₃:NH₄Cl:CeO₂ = 30:66:3:1 was used to aluminize γ-TiAl intermetallic compound specimens via pack cementation at 600 °C for 5 h. Subsequent isothermal oxidation at 900 °C for 20 h yielded an oxidation kinetic curve adhering to the parabolic rate law. This treatment significantly enhanced the high-temperature oxidation resistance of the γ-TiAl intermetallic compound, thereby broadening its potential application scenarios. Full article

We investigated the protective properties of ultrathin laminated coatings, comprising three pairs of Al₂O₃ and TiO₂ sublayers with coating thicknesses < 150 nm, deposited on AISI 310 stainless steel (SS) and Si (100) substrates at 80–500 °C by atomic layer deposition. The coatings were chemically etched and subjected to corrosion, ultrasound, and thermal shock tests. The coating etching resistance efficiency (R_e) was determined by measuring via XRF the change in the coating sublayer mass thickness after etching in hot 80% H₂SO₄. The maximum R_e values of ≥98% for both alumina and titania sublayers were obtained for the laminates deposited at 250–400 °C on both substrates. In these coatings, the titania sublayers were crystalline. The lowest R_e values of 15% and 50% for the alumina and titania sublayers, respectively, were measured for laminate grown at 80 °C on silicon. The coatings deposited at 160–200 °C demonstrated a delay in the increase of R_e values, attributed to the changes in the titania sublayers before full crystallization. Coatings grown at higher temperatures were also more resistant to ultrasound and liquid nitrogen treatments. In contrast, coatings deposited at 125 °C on SS had better corrosion protection, as demonstrated via electrochemical impedance spectroscopy and a standard immersion test in FeCl₃ solution. Full article

Divinylisoprene rubber, a copolymer of butadiene and isoprene, is used as raw material for rubber technical products, combining isoprene rubber’s elasticity and butadiene rubber’s wear resistance. These properties depend quantitatively on the copolymer composition, which depends on the kinetics of its synthesis. This work aims to theoretically describe how the monomer mixture composition in the butadiene–isoprene copolymerization affects the activity of the TiCl₄-Al(i-C₄H₉)₃ catalytic system (expressed by active sites concentration) via kinetic modeling. This enables development of a reliable kinetic model for divinylisoprene rubber synthesis, predicting reaction rate, molecular weight, and composition, applicable to reactor design and process intensification. Active sites concentrations were calculated from experimental copolymerization rates and known chain propagation constants for various monomer compositions. Kinetic equations for active sites formation were based on mass-action law and Langmuir monomolecular adsorption theory. An analytical equation relating active sites concentration to monomer composition was derived, analyzed, and optimized with experimental data. The results show that monomer composition’s influence on active sites concentration is well described by a two-step kinetic model (physical adsorption followed by Ti–C bond formation), accounting for competitive adsorption: isoprene adsorbs more readily, while butadiene forms more stable active sites. Full article

Antimicrobial resistance (AMR) poses a critical global health threat by rendering existing antibiotics ineffective against infections, leading to increased mortality, prolonged illnesses, and higher healthcare costs. Developing new antibiotics is essential to combat resistant pathogens, safeguard modern medical procedures, and prevent a return to a pre-antibiotic era where common infections become untreatable. We report a series of chiral tricarbonyl rhenium(I) complexes incorporating enantiopure pinene-substituted bipyridine ligands (L#) of the general formula fac-[Re(CO)₃L#X] and fac-[Re(CO)₃L#Py]⁺ (where X = Cl or Br and Py = pyridine). These complexes were isolated as mixtures of two diastereomers, characterized by standard techniques, and evaluated for cytotoxic activity against methicillin-resistant and methicillin-sensitive Staphylococcus aureus (MRSA and MSSA). The results revealed notable antibacterial efficacy (MIC = 1.6 μM), reflected in high therapeutic indices (Ti > 10). In contrast, analogous complexes bearing non-chiral 2,2′-bipyridine ligands exhibited no activity, underscoring the critical role of chirality in modulating biological interactions at the molecular level. These findings highlight the potential of chiral Re(I) complexes as promising scaffolds for the development of more potent and selective antibacterial agents. Full article

A scalable synthesis of two-dimensional titanium nitride chloride (TiNCl) via flash Joule heating (FJH) using titanium tetrachloride (TiCl₄) precursor has been developed. This single-step method overcomes traditional synthesis challenges, including high energy consumption, multi-step procedures, and hazardous reagent requirements. The structural and chemical properties of the synthesized TiNCl were characterized through multiple analytical techniques. X-ray diffraction (XRD) patterns confirmed the presence of TiNCl phase, while Raman spectroscopy data showed no detectable oxide impurities. Fourier transform infrared spectroscopy (FTIR) analysis revealed characteristic Ti–N stretching vibrations, further confirming successful titanium nitride synthesis. Transmission electron microscopy (TEM) imaging revealed thin, plate-like nanostructures with high electron transparency. These analyses confirmed the formation of highly crystalline TiNCl flakes with nanoscale dimensions and minimal structural defects. The material exhibits excellent structural integrity and phase purity, demonstrating potential for applications in photocatalysis, electronics, and energy storage. This work establishes FJH as a sustainable and scalable approach for producing MXenes with controlled properties, facilitating their integration into emerging technologies. Unlike conventional methods, FJH enables rapid, energy-efficient synthesis while maintaining material quality, providing a viable route for industrial-scale production of two-dimensional materials. Full article

Over efficient photocatalysts, CO₂ photoreduction typically converts CO₂ into low-carbon chemicals, which serve as raw materials for downstream synthesis processes. Here, an efficient composite photocatalyst heterojunction (Cu₂O-u/g-C₃N₄) has been fabricated to reduce CO₂. Graphitic carbon nitride (g-C₃N₄) was synthesized via thermal polymerization of urea at 550 °C, while pre-dispersed Cu₂O derived from urea pyrolysis (Cu₂O-u) was prepared by thermal reduction of urea and CuCl₂·2H₂O at 180 °C. The heterojunction Cu₂O-u/g-C₃N₄ was subsequently constructed through hydrothermal treatment at 180 °C. This heterojunction exhibited a bandgap of 2.10 eV, with dual optical absorption edges at 485 nm and above 800 nm, enabling efficient harvesting of solar light. Under 175 W mercury lamp irradiation, the heterojunction catalyzed liquid-phase CO₂ photoreduction to formic acid, acetic acid, and methanol. Its formic acid production activity surpassed that of pristine g-C₃N₄ by 3.14-fold and TiO₂ by 8.72-fold. Reaction media, hole scavengers, and reaction duration modulated product selectivity. In acetonitrile/isopropanol systems, formic acid and acetic acid production reached 579.4 and 582.8 μmol·h⁻¹·g_cat⁻¹. Conversely, in water/triethanolamine systems, methanol production reached 3061.6 μmol·h⁻¹·g_cat⁻¹, with 94.79% of the initial conversion retained after three cycles. Finally, this work ends with the conclusions of the CO₂ photocatalytic reduction to formic acid, acetic acid, and methanol, and recommends prospects for future research. Full article

A comparison of two synthesis methods for depositing Au nanoparticles onto TiO₂ was performed: (1) impregnation with HAuCl₄ followed by thermal treatment in argon, and (2) magnetron sputtering from a Au disc. The obtained materials were used for acetaldehyde decomposition in a high temperature reaction chamber and ch aracterised by UV-Vis/DR, XPS, XRD, SEM, and photoluminescence measurements. The process was carried out using an air/acetaldehyde gas flow under UV or UV-Vis LED irradiation. The mechanism of acetaldehyde decomposition and conversion was elaborated by in situ FTIR measurements of the photocatalyst surface during the reaction. Simultaneously, concentration of acetaldehyde in the outlet gas was monitored using gas chromatography. All the Au/TiO₂ samples showed absorption in the visible region, with a maximum around 550 nm. The plasmonic effect of Au nanoparticles was observed under UV-Vis light irradiation, especially at elevated temperatures such as 100 °C, for Au/TiO₂ prepared by the magnetron sputtering method. This resulted in a significant increase in the conversion of acetaldehyde at the beginning, followed by gradual decrease over time. The collected FTIR spectra indicated that, under UV-Vis light, acetaldehyde was strongly adsorbed onto Au/TiO₂ surface and formed crotonaldehyde or aldol. Under UV, acetaldehyde was mainly adsorbed in the form of acetate species. The plasmonic effect of Au nanoparticles increased the adsorption of acetaldehyde molecules onto TiO₂ surface, while reducing their decomposition rate. The increased temperature of the process enhanced the decomposition of the acetaldehyde. Full article

The anodic oxidation of titanium implants is a practical, cost-effective method to enhance implant success, especially due to rising hypersensitivity concerns. This study investigated the electrochemical behavior, surface characteristics, and biocompatibility of anodized commercially pure titanium (cpTi, grade IV). Anodization is performed on polished, cleaned cpTi sheet samples in 1 M H₂SO₄ using a constant voltage of 15 V for 15 and 45 min. The color of the oxide layer is evaluated using the CIELab color space, while composition is analyzed by a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). Additionally, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) are performed to identify and monitor the phase transformations of the formed titanium oxides. Corrosion measurements are performed in 9 g L⁻¹ NaCl, pH = 7.4, and show the excellent corrosion stability of the anodized samples in comparison with pure titanium. The biological response is assessed by determining mitochondrial activity and gene expression in human fibroblasts. Anodized surfaces, particularly Ti-45, promote higher mitochondrial activity and the upregulation of adhesion-related genes (N-cadherin and Vimentin) in human gingival fibroblasts, indicating improved biocompatibility and the potential for enhanced early soft tissue integration. Full article