Long Carbon-Carbon Bonding beyond 2 Å in Tris(9-fluorenylidene)methane.

We report on our investigation of C-C bonding longer than 2.0 Å, which can be realized by perpendicularly facing two fluorenyl rings in the title compound. A small orbital overlap between the distantly positioned carbon atoms is observed as a small concentration of electrons on the X-ray electron density map. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the compound originate from the in-phase and out-of-phase interactions of the overlapping orbitals, respectively, with a gap of 2.39 eV. Solid-state 13C NMR spectroscopy shows a sharp peak at 82.9 ppm for the long-bonded carbons, and a CASSCF(6,6) calculation indicates small diradical character. The experimental and theoretical analyses reveal sufficient covalent-bonding interaction in the long-bonded carbon pair.

Recovery of Valuable Solutes from Organic Solvent/Water Mixtures via Direct Contact Membrane Distillation (DCMD) as a Non-Heated Process.

Recently, the demand for the recovery of valuable solutes from organic solvents/water mixtures has increased in various fields. Furthermore, due to the abundance of heat-sensitive valuable solutes, the demand for non-heated concentration technologies has increased. In this study, the direct contact membrane distillation (DCMD) using hydrophobic polyvinylidene difluoride (PVDF) hollow fiber membranes was investigated to confirm the possibility of recovering valuable solutes from organic solvents/water mixtures as a non-heated process. The DCMD with 1000 ppm NaCl aqueous solution achieved 0.8 kg/m2·h of vapor flux and >99.9% of NaCl retention, even at feed and coolant temperatures of 25 and 10 °C, respectively. Furthermore, when DCMD was conducted under various conditions, including feed temperatures of 25, 35 and 45 °C, and organic solvent concentration of 15, 30 and 50 wt%, using ethanol/water and acetonitrile/water mixtures containing 1000 ppm NaCl. A surfactant was also used as a valuable solute, in addition to NaCl. As a result, it was found that the total vapor flux increased with increasing temperature and concentration of organic solvents, as the partial vapor pressure of the organic solvents increased. Additionally, no solute leaked under any condition, even when the surfactant was used as a valuable solute.

Development of a Basic Educational Kit for Robotic System with Deep Neural Networks.

In many robotics studies, deep neural networks (DNNs) are being actively studied due to their good performance. However, existing robotic techniques and DNNs have not been systematically integrated, and packages for beginners are yet to be developed. In this study, we proposed a basic educational kit for robotic system development with DNNs. Our goal was to educate beginners in both robotics and machine learning, especially the use of DNNs. Initially, we required the kit to (1) be easy to understand, (2) employ experience-based learning, and (3) be applicable in many areas. To clarify the learning objectives and important parts of the basic educational kit, we analyzed the research and development (R&D) of DNNs and divided the process into three steps of data collection (DC), machine learning (ML), and task execution (TE). These steps were configured under a hierarchical system flow with the ability to be executed individually at the development stage. To evaluate the practicality of the proposed system flow, we implemented it for a physical robotic grasping system using robotics middleware. We also demonstrated that the proposed system can be effectively applied to other hardware, sensor inputs, and robot tasks.

Effect of the Characteristic Properties of Membrane on Long-Term Stability in the Vacuum Membrane Distillation Process.

Membrane distillation (MD) is a technology that can treat feed solutions with higher osmotic pressure, as well as produce high-purity water. However, the water production cost of the MD process is expensive. In this study, to decrease the water production cost, we attempted to evaluate the effect of membrane characteristics on the long-term stability of a vacuum MD (VMD) system. We fabricated four different types of polyvinylidene difluoride hollow fiber membranes, and operated a VMD system with 3.5 wt% NaCl aqueous solution at 65 °C as a feed under 11 kPa of air gap pressure. Consequently, in the proposed VMD system, it is found that the liquid entry pressure (LEP) is the most important factor. When LEP was higher than 0.37 MPa, the pilot-scale module was very stable for long-term operations, and the vapor flux was approximately 19.3 kg/m2·h with a total salt retention factor of over 99.9% during the 300-h operation.

Magnetic-field-induced insulator-metal transition in W-doped VO2 at 500 T.

Metal-insulator (MI) transitions in correlated electron systems have long been a central and controversial issue in material science. Vanadium dioxide (VO2) exhibits a first-order MI transition at 340 K. For more than half a century, it has been debated whether electron correlation or the structural instability due to dimerised V ions is the more essential driving force behind this MI transition. Here, we show that an ultrahigh magnetic field of 500 T renders the insulator phase of tungsten (W)-doped VO2 metallic. The spin Zeeman effect on the d electrons of the V ions dissociates the dimers in the insulating phase, resulting in the delocalisation of electrons. As the Mott-Hubbard gap essentially does not depend on the spin degree of freedom, the structural instability is likely to be the more essential driving force behind the MI transition.

Synthesis of dansyl-labeled probe of thiophene analogue of annonaceous acetogenins for visualization of cell distribution and growth inhibitory activity toward human cancer cell lines.

The convergent synthesis of the dansyl-labeled probe of the thiophene-3-carboxamide analogue of annonaceous acetogenins, which shows potent antitumor activity, was accomplished by two asymmetric alkynylations of the 2,5-diformyl THF equivalent with an alkyne having a thiophene moiety and another alkyne tagged with a dansyl group. The growth inhibitory profiles toward 39 human cancer cell lines revealed that the probe retained the biological function of its mother compound, and would be useful for studying cellular activity.

Critical role of a methyl group on the γ-lactone ring of annonaceous acetogenins in the potent inhibition of mitochondrial complex I.

C34-epi and C34-epi-C35-trifluoro analogues of solamin, a mono-THF annonaceous acetogenin, were synthesized. Their inhibitory activity, along with previously synthesized analogues (C35-fluoro, C35-difluoro, and C35-trifluorosolamins), against bovine mitochondrial NADH-ubiquinone oxidoreductase (complex I) was determined. The present study revealed that the methyl group on the γ-lactone moiety is critical to the potent inhibition of complex I by natural acetogenins.

Design and synthesis of C35-fluorinated solamins and their growth inhibitory activities against human cancer cell lines.

The convergent synthesis of C35-fluorinated analogues of solamin, a mono-THF Annonaceous acetogenin, has been achieved by the Sonogashira coupling of the THF ring fragment and the fluorinated γ-lactone fragment. It was revealed that the number of fluorine atoms on the γ-lactone moiety affects the growth inhibitory activities against human cancer cell lines.

Convergent synthesis of fluorescence-labeled probes of Annonaceous acetogenins and visualization of their cell distribution.

The convergent synthesis of fluorescence-labeled solamin, an antitumor Annonaceous acetogenin, was accomplished by two asymmetric alkynylations of 2,5-diformyl tetrahydrofuran with an alkyne tagged with fluorescent groups and another alkyne with an α,ß-unsaturated γ-lactone. Assay for the growth inhibitory activity against human cancer cell lines revealed that the probe with the fluorescent groups at the end of the hydrocarbon chain may have the same mode of action as natural acetogenins. The merged fluorescence of dansyl-labeled solamin and MitoTracker Red suggests that Annonaceous acetogenins localize in the mitochondria.