Investigation of Nd3+ incorporation in Ce-rhabdophane: Insight from structural flexibility and occupation mechanism

LnPO₄ · 0.667H₂O rhabdophane has been considered as a potential material for the precipitation of actinides from radioactive waste liquid, owing to its outstanding characteristics of high actinide bearing and easy synthesis in acid solutions. However, a comprehensive understanding of the actinide occupation and the precipitation response of rhabdophane to remove actinides has yet to be established. In this study, the effect of ions concentration and pH values on the detailed precipitation reaction of Ce_xNd_1-xPO₄ · 0.667H₂O rhabdophane in acid solutions are systematically investigated. Some specific issues such as structural distortion and flexibility, and occupation mechanism are discussed by combining with experiments and density functional theory (DFT) calculation. The results reveal that ions concentration and pH values have a significant impact on the crystallization nucleation step before 12 h. The obtained removal rate of Nd³⁺ is more than 99% in pH 1–5 solutions with the ions concentration of 0.05–0.1 mol/L. Moreover, incorporating Nd in CePO₄ · 0.667H₂O rhabdophane will easily result in the lattice distortion in b-axis. DFT calculation and X-ray photoelectron spectroscopy (XPS) results reveal that Nd is preferentially incorporated in nonhydrated site to form a weaker binding energy of NdO₈ polyhedron.     

Preparation,structural, and characterizations of SnO2-coated TiNb2O7 anode materials for lithium-ion batteries

SnO₂-coated TiNb₂O₇ powders were synthesized via the solution coating method in the present research. The SnO₂ layers with a thickness of 3–5 nm were homogeneously coated on the surface of TiNb₂O₇ particles. TiNb₂O₇ coated with SnO₂ of 5 mol% with high Li⁺ diffusion coefficient delivered the discharge capacity of 319.5 mAh/g, which was 6.6% higher than that of the non-coated samples. The enhancement of capacity for the coated TiNb₂O₇ was owing to the low charge-transfer resistance of 17.5 Ω in contrary to the non-coated TiNb₂O₇ (27.8 Ω). SnO₂-coated TiNb₂O₇ possessed an improved capacity retention of 85.2% at 5 C after 100 cycles, superior to the non-coated TiNb₂O₇ (79.8%). On the other hand, the excessive amounts of SnO₂ coating led to the reduction in the capacity of the prepared samples. The excessive amounts of SnO₂ layers suppressed the Li⁺ diffusion and increased the charge-transfer resistance. The obtained results in this study indicated that coating of TiNb₂O₇ with appropriate amounts of SnO₂ significantly improved the electrochemical performance of TiNb₂O₇.     

Fluorobenzene Nucleobase Analogues for Triplex-Forming Peptide Nucleic Acids

2,4-Difluorotoluene is a nonpolar isostere of thymidine that has been used as a powerful mechanistic probe to study the role of hydrogen bonding in nucleic acid recognition and interactions with polymerases. In the present study, we evaluated five fluorinated benzenes as nucleobase analogues in peptide nucleic acids designed for triple helical recognition of double helical RNA. We found that analogues having para and ortho fluorine substitution patterns (as in 2,4-difluorotoluene) selectively stabilized Hoogsteen triplets with U−A base pairs. The results were consistent with attractive electrostatic interactions akin to non-canonical F to H−N and C−H to N hydrogen bonding. The fluorinated nucleobases were not able to stabilize Hoogsteen-like triplets with pyrimidines in either G−C or A−U base pairs. Our results illustrate the ability of fluorine to engage in non-canonical base pairing and provide insights into triple helical recognition of RNA.     

Host-Assisted Delivery of a Model Drug to Genomic DNA: Key Information from Ultrafast Spectroscopy and in silico Study

Drug delivery to a target without adverse effects is one of the major criteria for clinical use. Herein, we have made an attempt to explore the delivery efficacy of SDS surfactant in a monomer and micellar stage during the delivery of the model drug, Toluidine Blue (TB) from the micellar cavity to DNA. Molecular recognition of pre-micellar SDS encapsulated TB with DNA occurs at a rate constant of k₁ ∼652 s⁻¹. However, no significant release of encapsulated TB at micellar concentration was observed within the experimental time frame. This originated from the higher binding affinity of TB towards the nano-cavity of SDS at micellar concentration which does not allow the delivery of TB from the nano-cavity of SDS micelles to DNA. Thus, molecular recognition controls the extent of DNA recognition by TB which in turn modulates the rate of delivery of TB from SDS in a concentration-dependent manner.     

1-[2-(1-Cyclobutylpiperidin-4-yloxy)-6,7-dihydro-4H-thiazolo[5,4-c]pyridin-5-yl]propan-1-one: a Histamine H3 Receptor Inverse Agonist with Efficacy in Animal Models of Cognition

A series of chemical optimizations, which was guided by in vitro affinity at histamine H₃ receptor (H₃R), modulation of lipophilicity, ADME properties and preclinical efficacy resulted in the identification of 1-[2-(1-cyclobutylpiperidin-4-yloxy)-6,7-dihydro-4H-thiazolo[5,4-c]pyridin-5-yl]propan-1-one ( 45 e ) as a potent and selective (K_i=4.0 nM) H₃R inverse agonist. Dipsogenia induced by (R)-α-methylhistamine was dose dependently antagonized by 45 e , confirming its functional antagonism at H₃R. It is devoid of hERG and phospholipidosis issues. Compound 45 e has adequate oral exposures and favorable half-life in both rats and dogs. It has demonstrated high receptor occupancy (ED₈₀=0.22 mg/kg) and robust efficacy in object recognition task and, dose dependently increased acetylcholine levels in brain. The sub-therapeutic doses of 45 e in combination with donepezil significantly increased acetylcholine levels. The potent affinity, selectivity, in vivo efficacy and drug like properties together with safety, warrant for further development of this molecule for potential treatment of cognitive disorders associated with Alzheimer's disease.     

Synthesis of Dihydrobenzofuro[3,2-b]chromenes as Potential 3CLpro Inhibitors of SARS-CoV-2: A Molecular Docking and Molecular Dynamics Study

The recent emergence of pandemic of coronavirus (COVID-19) caused by SARS-CoV-2 has raised significant global health concerns. More importantly, there is no specific therapeutics currently available to combat against this deadly infection. The enzyme 3-chymotrypsin-like cysteine protease (3CLpro) is known to be essential for viral life cycle as it controls the coronavirus replication. 3CLpro could be a potential drug target as established before in the case of severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV). In the current study, we wanted to explore the potential of fused flavonoids as 3CLpro inhibitors. Fused flavonoids (5a,10a-dihydro-11H-benzofuro[3,2-b]chromene) are unexplored for their potential bioactivities due to their low natural occurrences. Their synthetic congeners are also rare due to unavailability of general synthetic methodology. Here we designed a simple strategy to synthesize 5a,10a-dihydro-11H-benzofuro[3,2-b]chromene skeleton and it's four novel derivatives. Our structural bioinformatics study clearly shows excellent potential of the synthesized compounds in comparison to experimentally validated inhibitor N3. Moreover, in-silico ADMET study displays excellent druggability and extremely low level of toxicity of the synthesized molecules. Further, for better understanding, the molecular dynamic approach was implemented to study the change in dynamicity after the compounds bind to the protein. A detailed investigation through clustering analysis and distance calculation gave us sound comprehensive data about their molecular interaction. In summary, we anticipate that the currently synthesized molecules could not only be a potential set of inhibitors against 3CLpro but also the insights acquired from the current study would be instrumental in further developing novel natural flavonoid based anti-COVID therapeutic spectrums.     

Development of spark plasma sintered conductive SiC–TiB2 composites for electrical discharge machining applications

Highly dense electrically conductive silicon carbide (SiC)–(0, 10, 20, and 30 vol%) titanium boride (TiB₂) composites with 10 vol% of Y₂O₃–AlN additives were fabricated at a relatively low temperature of 1800°C by spark plasma sintering in nitrogen atmosphere. Phase analysis of sintered composites reveals suppressed β→α phase transformation due to low sintering temperature, nitride additives, and nitrogen sintering atmosphere. With increase in TiB₂ content, hardness increased from 20.6 to 23.7 GPa and fracture toughness increased from 3.6 to 5.5 MPa m^1/2. The electrical conductivity increased to a remarkable 2.72 × 10³ (Ω cm)^–1 for SiC–30 vol% TiB₂ composites due to large amount of conductive reinforcement, additive composition, and sintering in nitrogen atmosphere. The successful electrical discharge machining illustrates potential of the sintered SiC–TiB₂ composites toward extending the application regime of conventional SiC-based ceramics.     

Angular absorptance and thermal degradation analysis of TiB2/Ti(B,N)/SiON/SiO2 multilayer solar absorber coating

Multilayer solar selective absorber coatings have been developed in the last few decades. The thermal stability in terms of microstructure gives an insightful understanding of the optical properties of such coatings. In this context, we extensively utilized transmission electron microscopy (TEM) analysis to establish the thermal stability of TiB₂/Ti(B,N)/SiON/SiO₂ coating, under thermal cycling/continuous heating to 500°C in vacuum for 250 h. In particular, this work reports the variation in the solar absorptance of TiB₂/Ti(B,N)/SiON/SiO₂ coating with different angles of incidence of the solar radiation. Extensive analysis using the TEM technique reveals the presence of oxide interlayers that act as diffusion barrier layers to enhance the thermal stability of the coating. Computational simulation using SCOUT software validates the measured reflectance spectrum of the developed multilayer coating. The minor changes in absorptance and emissivity after heat treatment in vacuum at 500°C, together with high solar absorptance over a broad angular variation, establish the potential application of TiB₂/Ti(B,N)/SiON/SiO₂ as a selective coating in concentrated solar power systems.     

Micellar Growth in Cetylpyridinium Chloride/Alcohol System: Role of Long Chain Alcohol,Electrolyte and Surfactant Head Group

The microstructural transition of aqueous 0.1 M cetylpyridinium chloride (CPC) in the combined presence of salt KBr and long chain alcohol (C₉OH-C₁₂OH) has been studied as a function of alcohol concentration, electrolyte concentration and temperature. The viscosity of the CPC/KBr micellar system showed a peaked behavior with alcohol concentration (C ₀), due to alcohol induced structural transition, which was confirmed by dynamic light scattering (DLS) and rheological analysis. Besides C ₀, the chain length of alcohol (n) was found to show a remarkable effect on the micellization behavior of CPC/KBr system. It was observed that the ability of alcohol to induce micelle growth diminishes with n, which was well supported by viscosity, rheology and DLS measurements. To examine the effect of the electrolyte on the micellar growth, the salt concentration was varied from 0.05 to 0.15 M and it was observed that with increase in [KBr], the peak position shifts towards lower C ₀. The effect of temperature on the micellar system showed interesting phase behavior for CPC/KBr/Decanol. The system exhibited a closed solubility loop with an upper critical solution temperature (UCST) > the lower critical solution temperature (LCST), reminiscence of nicotine-water system. The role of surfactant head group on the structural evolution was revealed by comparing the present results with our previous report for similar micellar system, CTAB/KBr/long chain alcohol.     

Modeling of single-lap composite adhesive joints under mechanical and thermal loads

Two-dimensional (plane-stress and plane-strain) theoretical models are presented for stress analysis of adhesively bonded single-lap composite joints subjected to either thermal or mechanical loading or a combination thereof. The joints consist of similar/dissimilar orthotropic or isotropic adherends and an isotropic adhesive interlayer. The governing differential equation of the problem is obtained using a variational method which minimizes the complementary strain energy in the bonded assembly. In this formulation, through-thickness variation of shear and peel stresses in the interlayer is considered. Both shear and normal traction-free boundary conditions are exactly satisfied. Peel and shear stresses obtained from plane-strain analytical models considering a homogeneous adhesive interlayer are in close agreement with those of the finite element predictions. A systematic parametric study is also conducted to identify an ideal set of geometric and material parameters for the optimal design of single-lap composite joints.