Bismuth Oxyiodide Nanoflakes Showed Toxicity Against the Malaria Vector <Emphasis Type="Italic">Anopheles stephensi</Emphasis> and In Vivo Antiplasmodial Activity

Anopheles stephensi is a mosquito vector of malaria, which is still considered a relevant public health problem due to increasing outdoor transmission, growing resistance to insecticides used to target vectors, and antiplasmodial drugs as well. Thus, there is a vital need to explore novel sources of effective compounds. In this study, the hydrothermal method was used for the synthesis of bismuth oxyiodide (BiOI) nanoflakes. Furthermore, the toxicity of BiOI nanoflakes was evaluated for the first time on A. stephensi, as well as in vivo against the malaria parasite Plasmodium berghei. The synthesis of BiOI nanoflakes was confirmed by various characterization techniques, including X-ray diffraction, Fourier transform-infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy (HR-TEM). LC₅₀ of BiOI nanoflakes on A. stephensi were 2.263 ppm (larva I), 3.414 ppm (II), 4.956 ppm (III), 6.983 ppm (IV) and 8.605 ppm (pupae). In vivo antiplasmodial experiments conducted on P. berghei infecting albino mice showed 27.2% of chemosuppression after 4 days of treatment with 300 mg/kg/day of BiOI, a lower performance if compared to chloroquine. Overall, our results suggested that hydrothermal synthesis of BiOI nanoflakes may be considered to develop newer and safer tools for malaria vector control.     

Transmission electron microscopy observation of GaAs/Al0.3Ga0.7As T-shaped quantum well structure fabricated by glancing angle molecular beam epitaxy on GaAs(100) reverse-mesa etched substrates

GaAs/Al_0.3Ga_0.7As multi-layer structures were grown on GaAs (100) reverse-mesa etched substrates by glancing angle molecular beam epitaxy (GA-MBE). A(111)B facet was formed as a side-facet. Surface migration of Ga and Al atoms from the (100) flat region to the (111)B side-facet region has been investigated to fabricate T-shaped GaAs/AlGaAs quantum wells (QWs) under the condition that Ga and Al atoms impinge only an the (100) flat region and do not impinge on the (111)B side-facet. Observation of T-shaped GaAs/AlGaAs quantum wires (QWRs) by cross-sectional transmission electron microscopy (TEM) revealed that there is no migration of Al atoms from the (100) to the (111)B facet region at a substrate temperature (T_s) as high as 630°C, under a V/III ratio of 28 (in pressure ratio). On the other hand, very thin GaAs epitaxial layers grown on the (111)B side-facet region owing to the Ga migration were observed for substrate temperatures of 600 and 630°C. It was found that the mass flow of Ga atoms from the (100) region to the (111)B side-facet region increases, with the thermal activation energy of 2.0 eV, as the substrate temperature increases from 570 to 630°C. The GA-MBE growth on a reverse-mesa etched GaAs substrate at a low temperature 570°C or lower is desirable to fabricate a nm-scale GaAs/AlGaAs QWR structure with nm-scale precision.     

Thiophene donor-acceptor [2]rotaxanes

A series of the thiophene donor-acceptor [2]rotaxanes have been synthesized based on the inclusion complexes of cyclobis(paraquat- p-phenylene) (CBPQT4+) with thiophene, bithiophene, and terthiophene. The maximum wavelength of the charge-transfer band strongly depends on the number of thiophene units, while the association constant does not. These donor-acceptor pairs will be fascinating constituents for optoelectronic and electromechanical materials.     

Highly sensitive restriction enzyme assay and analysis: a review

Biological assays at the single molecule level are crucial to fundamental studies of DNA-protein mechanisms. In order to cater for high throughput applications, one area of immense research potential is single-molecule bioassays where miniaturized devices are developed to perform rapid and effective biological reactions and analyses. With the success of various emerging technologies for engineering miniaturized structures down to the nanoscale level, supported by specialized equipment for detection, many investigations in the field of life science that were once thought impossible can now be actively explored. In this review, the significance of downscaling to the single-molecule level is firstly presented in selected examples, with the focus placed on restriction enzyme assays. To determine the effectiveness of single-molecule restriction enzyme reactions, simple and direct analytical methods based on DNA stretching have often been reliably employed. DNA stretching can be realized based on a number of working principles related to the physical forces exerted on the DNA samples. We then discuss two examples of a nanochannel system and a microchamber system where single-molecule restriction enzyme digestion and DNA stretching have been integrated, which possess prospective capabilities of developing into highly sensitive and high-throughput restriction enzyme assays. Finally, we take a brief look at the general trends in technological development in this field by comparing the advantages and disadvantages of performing assays at bulk, microscale and single-molecule levels. Figure Minaturization of Restriction Enzyme Assays and DNA Stretching     

Structure of an unsaturated fatty acid with unique vicinal dimethyl branches isolated from the Okinawan soft coral of the genus Sinularia

A new unsaturated fatty acid with unique vicinal dimethyl branches was isolated from the Okinawan soft coral of the genus Sinularia. The structure of the compound was determined based on the results of spectroscopic analysis and chemical conversion. The absolute configuration was deduced by applying the Ohrui-Akasaka method.     

Adaptive Ion-Gel: Stimuli-Responsive,and Self-Healing Ion Gels

Ion gels are an emerging class of polymer gels in which a three-dimensional polymer network swells with an ionic liquid. Ion gels have drawn considerable attention in various fields such as energy and biotechnology owing to their excellent properties including nonvolatility, nonflammability, high ionic conductivity, and high thermal and electrochemical stability. Since the first report on ion gels (published ∼30 years ago), diverse functional ion gels exhibiting impressive physicochemical properties have been reported. In this review, recent developments in functional ion gels that can modulate their physical properties in response to environmental conditions are outlined. Stimuli-responsive ion gels that can adaptively undergo phase transitions in response to thermal and light stimuli are initially discussed, followed by an evaluation of diverse self-healing ion gels that can spontaneously mend mechanical damage through judiciously designed ion-gel networks.     

Recent Advances in Self‐Oscillating Polymer Material Systems

In 1996, we first reported self‐oscillating polymer gels exhibiting autonomous swelling‐deswelling oscillations driven by the Belousov‐Zhabotinsky reaction. In contrast to conventional stimuli‐responsive gels, the self‐oscillating gel can autonomously and periodically change its volume in a closed solution without any external stimuli. Since the first report, the novel concept of self‐oscillating gels has been expanded into various polymer and gel systems. Herein, we summarize recent advances in self‐oscillating polymers and gels.     

Synthesis and Applications of (ONO Pincer)Ruthenium‐Complex‐Bound Norvalines

Two (ONO pincer)ruthenium‐complex‐bound norvalines, Boc?[Ru(pydc)(terpy)]Nva?OMe ( 1 ; Boc=tert‐butyloxycarbonyl, terpy=terpyridyl, Nva=norvaline) and Boc?[Ru(pydc)(tBu‐terpy)]Nva?OMe ( 5 ), were successfully synthesized and their molecular structures and absolute configurations were unequivocally determined by single‐crystal X‐ray diffraction. The robustness of the pincer Ru complexes and norvaline scaffolds against acidic/basic, oxidizing, and high‐temperature conditions enabled us to perform selective transformations of the N‐Boc and C?OMe termini into various functional groups, such as alkyl amide, alkyl urea, and polyether groups, without the loss of the Ru center or enantiomeric purity. The resulting dialkylated Ru‐bound norvaline, n‐C₁₁H₂₃CO?l ‐[Ru(pydc)(terpy)]Nva?NH‐n‐C₁₁H₂₃ (l ‐ 4 ) was found to have excellent self‐assembly properties in organic solvents, thereby affording the corresponding supramolecular gels. Ru‐bound norvaline l ‐ 1 exhibited a higher catalytic activity for the oxidation of alcohols by H₂O₂ than parent complex [Ru(pydc)(terpy)] ( 11 a ).     

Synthesis, structure, and properties of benzoquinone dimer and trimers bearing t-Bu substituents

Highly soluble and stable quinone dimer and trimers were successfully yielded by introduction of t-Bu substituents. In X-ray structure analysis, the dimer quinone moiety was distorted into the boat shape, which was clarified by MO calculations. X-ray and UV/vis studies indicated that the covalently linked quinone moieties bear a large torsional angle. Nevertheless, the reduction potentials rose significantly with the order of monomer < dimer < trimer, indicating that the negative charge was efficiently delocalized within the radical anions.