Microwave‐Assisted Stereoselective 1,3‐Dipolar Cycloaddition of C,N‐Diarylnitrone (i.e., N‐(Arylmethylidene)benzenamine N‐Oxide) and Bis(arylmethylidene)acetone (=1,5‐Diarylpenta‐1,4‐dien‐3‐one): NMR and Crystal Analysis of Diastereoisomeric Bis(isoxazolidines)

Microwave‐assisted stereoselective 1,3‐dipolar cycloaddition of C,N‐diarylnitrones (i.e., N‐(arylmethylidene)benzenamine N‐oxides) 2 to substituted bis(arylmethylidene)acetones (=1,5‐diarylpenta‐1,4‐dien‐3‐ones) 1 leading to diastereoisomer pairs of bis‐isoxazolidines 3 and 4 in good to excellent yield is described (Scheme 2 and Table 2). The configuration outcome of the reaction is discussed based on the NMR and X‐ray data of the products.     

Continuum interpretation of virial stress in molecular simulations

The equivalence of the virial stress and Cauchy stress is reviewed using both theoretical arguments and numerical simulations. Using thermoelasticity problems as examples, we numerically demonstrate that virial stress is equivalent to the continuum Cauchy stress. Neglecting the velocity terms in the definition of virial stress as many authors have recently suggested, can cause significant errors in interpreting MD simulation results at elevated temperatures (T > 0 K).     

Tilianin: A Potential Natural Lead Molecule for New Drug Design and Development for the Treatment of Cardiovascular Disorders

Cardiovascular disorders (CVDs) are the leading risk factor for death worldwide, and research into the processes and treatment regimens has received a lot of attention. Tilianin is a flavonoid glycoside that can be found in a wide range of medicinal plants and is most commonly obtained from Dracocephalum moldavica. Due to its extensive range of biological actions, it has become a well-known molecule in recent years. In particular, numerous studies have shown that tilianin has cardioprotective properties against CVDs. Hence, this review summarises tilianin’s preclinical research in CVDs, as well as its mechanism of action and opportunities in future drug development. The physicochemical and drug-likeness properties, as well as the toxicity profile, were also highlighted. Tilianin can be a natural lead molecule in the therapy of CVDs such as coronary heart disease, angina pectoris, hypertension, and myocardial ischemia, according to scientific evidence. Free radical scavenging, inflammation control, mitochondrial function regulation, and related signalling pathways are all thought to play a role in tilianin’s cardioprotective actions. Finally, we discuss tilianin-derived compounds, as well as the limitations and opportunities of using tilianin as a lead molecule in drug development for CVDs. Overall, the scientific evidence presented in this review supports that tilianin and its derivatives could be used as a lead molecule in CVD drug development initiatives.     

Mesoporous γ‐Iron Oxide Nanoparticles for Magnetically Triggered Release of Doxorubicin and Hyperthermia Treatment

Mesoporous iron‐oxide nanoparticles (mNPs) were prepared by using a modified nanocasting approach with mesoporous carbon as a hard template. mNPs were first loaded with doxorubicin (Dox), an anticancer drug, and then coated with the thermosensitive polymer Pluronic F108 to prevent the leakage of Dox molecules from the pores that would otherwise occur under physiological conditions. The Dox‐loaded, Pluronic F108‐coated system (Dox@F108‐mNPs) was stable at room temperature and physiological pH and released its Dox cargo slowly under acidic conditions or in a sudden burst with magnetic heating. No significant toxicity was observed in vitro when Dox@F108‐mNPs were incubated with noncancerous cells, a result consistent with the minimal internalization of the particles that occurs with normal cells. On the other hand, the drug‐loaded particles significantly reduced the viability of cervical cancer cells (HeLa, IC₅₀=0.70 μm ), wild‐type ovarian cancer cells (A2780, IC₅₀=0.50 μm ) and Dox‐resistant ovarian cancer cells (A2780/AD, IC₅₀=0.53 μm ). In addition, the treatment of HeLa cells with both Dox@F108‐mNPs and subsequent alternating magnetic‐field‐induced hyperthermia was significantly more effective at reducing cell viability than either Dox or Dox@F108‐mNP treatment alone. Thus, Dox@F108‐mNPs constitute a novel soft/hard hybrid nanocarrier system that is highly stable under physiological conditions, temperature‐responsive, and has chemo‐ and thermotherapeutic modes of action.     

Homogeneity and critical current density of Sn-doped PbMo6S8 superconductors

With the overall critical current density,J _c , remaining low for PbMo₆S₈, the addition of 0.3 at. % Sn noticcably improved the performance. The enhancement occurs despite the presence of excess Pb and a slightly suppressedT _c . The increase inJ _c can be attributed to a better homogeneity with respect to the chemical composition of the samples, which may be as a consequence of Sn substitution in the lattice. Detailed calorimetric investigation of undoped PbMo₆S₈ showed aT _c distribution down to 9 K evidenced by a smearing ofT _c . This may be due to a progressive degradation of the sample quality leading to a plausible off-stoichiometry. High-resolution Auger electron spectroscopic experiments suggest a variation in composition indicating excellent correspondence with the specific heat data. However, no such deviation was detected for the Sn-doped samples and therefore the observed raise inJ _c . The results are discussed in conjunction with oxygen, lead and tin incorporated PbMo₆S₈.     

Universal quantification for deterministic chaos in dynamical systems

A cell dynamical system model for deterministic chaos enables precise quantification of the round-off error growth, i.e., deterministic chaos in digital computer realizations of mathematical models of continuum dynamical systems. The model predicts the following: (a) The phase space trajectory (strange attractor) when resolved as a function of the computer accuracy has intrinsic logarithmic spiral curvature with the quasiperiodic Penrose tiling pattern for the internal structure. (b) The universal constant for deterministic chaos is identified as the steady-state fractional round-off error k for each computational step and is equal to 1/τ² ( = 0.382) where τ is the golden mean. k being less than half accounts for the fractal (broken) Euclidean geometry of the strange attractor. (c) The Feigenbaum's universal constantsa and d are functions of k and, further, the expression 2a² = πd quantifies the steady-state ordered emergence of the fractal geometry of the strange attractor. (d) The power spectra of chaotic dynamical systems follow the universal and unique inverse power law form of the statistical normal distribution. The model prediction of (d) is verified for the Lorenz attractor and for the computable chaotic orbits of Bernoulli shifts, pseudorandom number generators, and cat maps.     

Studies on photocrosslinkable copolymers of 4-methacryloyloxyphenyl-3′,4′-dimethoxystyryl ketone and methyl methacrylate

Copolymers with various contents of 4-methacryloyloxyphenyl-3′,4′-dimethoxystyryl ketone (MPDSK) and methyl methacrylate (MMA) were prepared in methyl ethyl ketone solution using benzoyl peroxide as a free radical initiator at 70 °C. Characterization of the resulting polymers was done by UV, FT-IR, ¹H NMR and ¹³C NMR spectroscopic techniques. The copolymer compositions were determined by ¹H NMR analysis. The monomer reactivity ratios were calculated using linearisation methods such as Finemann-Ross (r₁ = 0.4283 and r₂ = 0.3050), Kelen-Tudos (r₁ = 0.4264 and r₂ = 0.2606), and extended Kelen-Tudos (r₁ = 0.4022 and r₂ = 0.2704) methods as well as by a non-linear error-in-variables model (EVM) method using the computer program RREVM (r₁ = 0.4066 and r₂ = 0.2802). The molecular weights ( and ) and the polydispersity index of the copolymers were determined by gel permeation chromatography. The thermal stability of the copolymers increases with increase in concentration of MPDSK. Glass transition temperatures were determined by differential scanning calorimeter under nitrogen atmosphere. The photoreactivity of the copolymers having pendant chalcone moieties was studied in chloroform solution.     

Schiff’s base phenol-hydrazone derivatives as colorimetric chemosensors for fluoride ions

Two new chromogenic receptors 4-nitro-2-[(phenylhydrazoimino)methyl]phenol (1) and 4-nitro-2-[(4-nitrophenylhydrazoimino)methyl]phenol (2) containing a nitro group as a signalling unit and OH and NH groups as binding sites have been synthesized and characterized by spectroscopic techniques and XRD. Both receptors show colorimetric responses and UV-vis spectral changes in the presence of fluoride ions in organic solvents.