Synthesis of Ternary and Quaternary Au and Pt Decorated CdSe/CdS Heteronanoplatelets with Controllable Morphology

A variety of new ternary and quaternary metal–semiconductor inorganic nanostructures with unprecedented structural morphologies is achieved by the decoration of five monolayer‐thick CdSe/CdS core/crown nanoplatelets with Au and Pt domains. Significant differences in metal growth behavior are observed by varying the CdSe core and the CdS crown dimensions. Depending on the core size, Au growth can be directed only to the CdS edges, or both at the edges and at the center of the nanoplatelets. In contrast, the nucleation of Pt domains always happens at the CdS edges independently of the core and crown dimensions. Furthermore, quaternary structures are obtained by additional Au growth on Pt‐decorated CdSe/CdS nanoplatelets, where the effect of steric hindrance of the existing Pt domains results in the Au nucleation to occur only at the CdSe core. Instead, a change in the order of growth of the two noble metals results in Pt‐Au alloys present only at the surrounding edges of the nanoplatelets. Additionally, the metal‐decorated nanoplatelets are found to be efficient catalysts for H₂ fuel generation under white light irradiation. The highest apparent quantum efficiency measured is 19.3% ± 1.4% with a turnover frequency of ≈10⁵ molecules of H₂ per hour per nanoplatelet.     

Probiotic potential of Saccharomyces cerevisiae and Kluyveromyces marxianus isolated from West African spontaneously fermented cereal and milk products

The yeast species Saccharomyces cerevisiae and Kluyveromyces marxianus are associated with fermentation of West African indigenous foods. The aim of this study was to characterize potential probiotic properties of S. cerevisiae and K. marxianus isolates from the West African milk products lait caillé and nunu and a cereal-based product mawè. The strains (14 in total) were identified by 26S rRNA gene sequencing and characterized for survival at gastrointestinal stress (bile salts and low pH) and adhesion to Caco-2 intestinal epithelial cells. Selected yeast isolates were tested for their effect on the transepithelial electrical resistance (TEER), using the intestinal epithelial cell line Caco-2 and for maintenance of intracellular pH (pH_i) during perfusion with gastrointestinal pH (3.5 and 6.5). All tested yeasts were able to grow in bile salts in a strain-dependent manner, exhibiting a maximum specific growth rate (μ_max) of 0.58–1.50 h⁻¹. At pH 2.5, slow growth was observed for the isolates from mawè (μ_max of 0.06–0.80 h⁻¹), whereas growth of yeasts from other sources was mostly inhibited. Yeast adhesion to Caco-2 cells was strain specific and varied between 8.0% and 36.2%. Selected strains of S. cerevisiae and K. marxianus were able to maintain the pH_i homeostasis at gastrointestinal pH and to increase TEER across the Caco-2 monolayers, indicating their potential to improve intestinal barrier functions. Based on overall results, strains of K. marxianus and S. cerevisiae from mawè exhibited the highest probiotic potential and might be recommended for further development as starter cultures in West African fermented products.     

Rust‐Mediated Continuous Assembly of Metal–Phenolic Networks

The use of natural compounds for preparing hybrid molecular films—such as surface coatings made from metal–phenolic networks (MPNs)—is of interest in areas ranging from catalysis and separations to biomedicine. However, to date, the film growth of MPNs has been observed to proceed in discrete steps (≈10 nm per step) where the coordination‐driven interfacial assembly ceases beyond a finite time (≈1 min). Here, it is demonstrated that the assembly process for MPNs can be modulated from discrete to continuous by utilizing solid‐state reactants (i.e., rusted iron objects). Gallic acid etches iron from rust and produces chelate complexes in solution that continuously assemble at the interface of solid substrates dispersed in the system. The result is stable, continuous growth of MPN films. The presented double dynamic process—that is, etching and self‐assembly—provides new insights into the chemistry of MPN assembly while enabling control over the MPN film thickness by simply varying the reaction time.     

Vitamin D Analogs Regulate the Vitamin D System and Cell Viability in Ovarian Cancer Cells

Background: Ovarian cancer (OC) is one of the most lethal cancers in women. The active form of vitamin D₃, 1,25-dihydroxyvitamin D₃ (1,25D₃, calcitriol) has anticancer activity in several cancers, including ovarian cancer, but the required pharmacological doses may cause hypercalcemia. We hypothesized that newly developed, low calcemic, vitamin D analogs (an1,25Ds) may be used as anticancer agents instead of calcitriol in ovarian cancer cells. Methods: We used two patient-derived high-grade serous ovarian cancer (HGSOC) cell lines with low (13781) and high (14433) mRNA expression levels of the gene encoding 1,25-dihydroxyvitamin D₃ 24-hydroxylase CYP24A1, one of the main target genes of calcitriol. We tested the effect of calcitriol and four structurally related series of an1,25Ds (PRI-1906, PRI-1907, PRI-5201, PRI-5202) on cell number, viability, the expression of CYP24A1, and the vitamin D receptor (VDR). Results: CYP24A1 mRNA expression increased in a concentration-dependent manner after treatment with all compounds. In both cell lines, after 4 h, PRI-5202 was the most potent analog (in 13781 cells: EC₅₀ = 2.98 ± 1.10 nmol/L, in 14433 cells: EC₅₀ = 0.92 ± 0.20 nmol/L), while PRI-1907 was the least active one (in 13781 cells: EC₅₀ = n/d, in 14433 cells: EC₅₀ = n/d). This difference among the analogs disappeared after 5 days of treatment. The 13781 cells were more sensitive to the an1,25Ds compared with 14433 cells. The an1,25Ds increased nuclear VDR levels and reduced cell viability, but only in the 13781 cell line. Conclusions: The an1,25Ds had different potencies in the HGSOC cell lines and their efficacy in increasing CYP24A1 expression was cell line- and chemical structure-dependent. Therefore, choosing sensitive cancer cell lines and further optimization of the analogs’ structure might lead to new treatment options against ovarian cancer.     

Histology and ultrastructure of Aedes albopictus larval midgut infected with Bacillus thuringiensis var. israelensis

Histological and ultrastrucutural alterations in the midgut of Aedes albopictus larvae infected with Bacillus thuringiensis var. israelensis (Bti) were observed by light and transmission electron microscopy (TEM). Two formulations of Bti were used: granulated and powder, with 0.2% active ingredient in 90 larvae of Ae. albopictus distributed in three containers containing 30 larvae each (one control group and two test groups). The midgut epithelium of the control group presented flattened and elongated cells with mace-shape with a narrow base. Midgut epithelium cells' surface was convex and had a large circular nucleus located in the median-apical portion of the cell. These cells also presented a basal lamina with a small accumulation of extracellular fibrous matrix, thus characterizing a basal membrane, with a muscle layer and a peritoneal membrane more externally. After Bti ingestion, the larvae stopped/slowed their natural movements down in 5 min. After 30 min approximately, the swimming movements stopped completely. Internally, the intestinal cells showed a disorganization of the basal processes, dilatation and fragmentation of the rough endoplasmic reticulum, with intense cytoplasmic vacuolization. There were concentric dense laminas accumulated in the cytoplasm, and these residual membranous bodies were seen greatly increased in size after 60 min. Mitochondria, fragments of rough endoplasmic reticulum and other remainder organelles were surrounded and segregated from the cytoplasm by exocytosis. This article reports the histopathological alterations in the midgut of Ae. albopictus after infection with Bti and contributes to a better understanding of the mode of action of this bacterial strain used as bioinsecticide against mosquito larvae.     

Nitrogen Doping Improves the Immobilization and Catalytic Effects of Co9S8 in Li‐S Batteries

Several critical issues, such as the shuttling effect and the sluggish reaction kinetics, exist in the design of high‐performance lithium–sulfur (Li‐S) batteries. Here, it is reported that nitrogen doping can simultaneously and significantly improve both the immobilization and catalyzation effects of Co₉S₈ nanoparticles in Li‐S batteries. Combining the theoretical calculations with experimental investigations, it is revealed that nitrogen atoms can increase the binding energies between LiPSs and Co₉S₈, and as well as alleviate the sluggish kinetics of Li‐S chemistry in the Li₂S₆ cathode. The same effects are also observed when adding N‐Co₉S₈ nanoparticles into the commercial Li₂S cathode (which has various intrinsic advantages, but unfortunately a high overpotential). A remarkable improvement in the battery performances in both cases is observed. The work brings heteroatom‐doped Co₉S₈ to the attention of designing high‐performance Li‐S batteries. A fundamental understanding of the inhibition of LiPSs shuttle and the catalytic effect of Li₂S in the newly developed system may encourage more effort along this interesting direction.     

Average parameterization and partial kernelization for computing medians

We propose an effective polynomial-time preprocessing strategy for intractable median problems. Developing a new methodological framework, we show that if the input objects of generally intractable problems exhibit a sufficiently high degree of similarity between each other on average, then there are efficient exact solving algorithms. In other words, we show that the median problems Swap Median Permutation, Consensus Clustering, Kemeny Score, and Kemeny Tie Score all are fixed-parameter tractable with respect to the parameter “average distance between input objects”. To this end, we develop the novel concept of “partial kernelization” and, furthermore, identify polynomial-time solvable special cases for the considered problems.     

Kinetics of geometrical isomerization of unsaturated FA in soybean oil

Laboratory treatment of soybean oil were carried out at the following conditions: atmospheric pressure in the presence of air or nitrogen at different temperatures ranging from 160 to 250°C for 12 to 72 h. These conditions were used to study geometric isomerization of cis,cis-linoleic and cis,cis,cis-linolenic acid in the presence or in the absence of oxidative degradation reactions. Based on these experiments, a model of consecutive, parallel reactions was developed to describe the reaction steps occurring in the soybean oil during heating at constant temperature. For both cis,cis-linoleic and cis,cis,cis-linolenic acid, the reaction of formation isomers followed a first-order reaction, and the rate constant of isomerization varied according to the Arrhenius law. The isomerization rate constant for linoleic acid was 9.57×10⁻³±0.50 h⁻¹ in the presence of oxygen and 7.39×10⁻³±0.39 h⁻¹ in its absence, and the isomerization rate constant for linolenic acid was 1.18×10⁻¹±0.10 h⁻¹ in the presence of oxygen and 0.87×10⁻¹±0.07 h⁻¹ in its absence (all obtained at 250°C).