Synthesis of Alkenylgold(I) Complexes Relevant to Catalytic Carboxylative Cyclization of Unsaturated Amines and Alcohols.

The carboxylation of unsaturated amine and alcohol compounds, including 4-benzylamino-1-phenyl-1-butyne (homopropargylamine), 2-butyne-1-ol (propargylic alcohol), and 2,3-butadiene-1-ol (allenylmethyl alcohol), using the hydroxidogold(I) complex, AuOH(IPr) [IPr = 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene], produces corresponding alkenylgold(I) complexes with a cyclic urethane or carbonate framework in high yields. The reaction takes place in aprotic THF at room temperature under the atmospheric pressure of CO in the absence of base additives. The products were characterized by NMR spectroscopy, elemental analysis, and X-ray crystallography.

Analysis of Unique Motility of the Unicellular Green Alga at Low Temperatures down to -8 °C.

Previous studies of motility at low temperatures in have been conducted at temperatures of up to 15 °C. In this study, we report that exhibits unique motility at a lower temperature range (-8.7 to 1.

Reddening of the Unicellular Green Alga by Dried Bonito Stock and Intense Red Light Irradiation.

This study confirms for the first time that the significant red coloration of is induced by bonito stock (BS), a traditional Japanese food, and intense red light exposure (605~660 nm, 1000~1300 µmol photons/m/s). Under the condition, excessive photosynthetic activity destroyed many chloroplasts, while carotenoids were maintained, resulting in the formation of reddened cells. The HPLC analysis revealed that diadinoxanthin was the primary carotenoid present in reddened cells.

Observation of Coherent Perfect Absorption in Oil Film on Water Surface and Sensitive Detection of Refractive Index Anisotropy in the Film.

Sharp reflection dips of 50% were observed when white light was incident from the side of a cell on a 1 μm thick film of silicone oil (polydimethylsiloxane, PDMS, nearly transparent in visible light, with the extinction coefficient κ ≈ 0.0001) above a water surface in the cell so that the total reflection condition was satisfied at the oil-air interface. This is the first observation of a coherent perfect absorption (CPA) phenomenon in liquid.

Spatial Distribution of Flagellated Microalgae in a Quasi-Two-Dimensional Space.

Although the phenomenon of collective order formation by cell-cell interactions in motile cells, microswimmers, has been a topic of interest, most studies have been conducted under conditions of high cell density, where the space occupancy of a cell population relative to the space size ϕ>0.1 (ϕ is the area fraction). We experimentally determined the spatial distribution (SD) of the flagellated unicellular green alga at a low cell density (ϕ≈0.

Development of a Simple Fabrication Method for Magnetic Micro Stir Bars and Induction of Rotational Motion in .

A magnetic micro stirrer bar (MMSB) is used in the mixing operation of microfluidic devices. We have established a low-cost and easy method to make MMSBs using magnetic (neodymium magnets, magnet sheets) or non-magnetic powders (SUS304) as materials. We demonstrated three kinds of MMSB have respective advantages.

Absorbance spectroscopy of light scattering samples placed inside an integrating sphere for wide dynamic range absorbance measurement.

In the absorbance measurement of a sample that scatters light significantly, it is necessary to consider the effect of the attenuation of incident light due to scattering on the measured absorbance. Since the usual absorbance measurement with an integrating sphere (IS) cannot remove the influence of backscattering, we performed the absorbance measurement considering the light scattered to almost all solid angles by placing the sample inside the IS. Ni(NO) and Co(NO) aqueous solutions were used as non-scattering samples, and Ni(NO) solutions mixed with submicrometer polystyrene spheres as scatterers were used as scattering samples.

Noninvasive and Safe Cell Viability Assay for Breast Cancer MCF-7 Cells Using Natural Food Pigment.

A dye exclusion test (DET) was performed to determine the viability of human breast cancer cells MCF-7, using natural food pigments as compared with trypan blue (TB), a typical synthetic dye for DET known to exhibit teratogenicity and cytotoxicity. We demonstrated that pigment (MP) is noninvasive to living cells and can effectively stain only dead cells. This study is the first verification of the applicability of MP to cancer cells.

Noninvasive and safe cell viability assay for Paramecium using natural pigment extracted from food.

Noninvasive, safe and cost-effective cell viability assay is important in many fields of biological research such as cell culture and counting. We examined ten typical natural pigments extracted from food to find that Monascus pigment (MP) or anthocyanin pigment (AP: purple sweet potato and purple cabbage) with Tris (Trimethylolaminomethane) works as a good indicator of viability assay for dye exclusion test (DET) of Paramecium. This was confirmed spectrally by scan-free, non-invasive absorbance spectral imaging A (x, y, λ) microscopy.

Enzymatic Conversion of Cypridina Luciferyl Sulfate to Cypridina Luciferin with Coenzyme A as a Sulfate Acceptor in Cypridina (Vargula) hilgendorfii.

In the luminous ostracod Cypridina (presently Vargula) hilgendorfii, Cypridina luciferyl sulfate (3-enol sulfate of Cypridina luciferin) is converted to Cypridina luciferin by a sulfotransferase with 3'-phosphoadenosine-5'-phosphate (PAP) as a sulfate acceptor. The resultant Cypridina luciferin is used for the luciferase-luciferin reaction of Cypridina to emit blue light. The luminescence stimulation with major organic cofactors was examined using the crude extracts of Cypridina specimens, and we found that the addition of coenzyme A (CoA) to the crude extracts significantly stimulated luminescence intensity.

Deep convolutional neural network for reduction of contrast-enhanced region on CT images.

This study aims to produce non-contrast computed tomography (CT) images using a deep convolutional neural network (CNN) for imaging. Twenty-nine patients were selected. CT images were acquired without and with a contrast enhancement medium.

Absorbance spectra of the hematochrome-like granules and eyespot of Euglena gracilis by scan-free absorbance spectral imaging A(x, y, λ) within the live cells.

Euglena gracilis has an organelle resembling hematochrome, with an appearance similar to the eyespot and the absorption band spectrally overlapped with that of the carotenoid. To discriminate the hematochrome-like granules and eyespot, scan-free, non-invasive, absorbance spectral imaging A(x, y, λ) microscopy of single live cells, where A(x, y, λ) means absorbance at a position (x, y) on a two-dimensional image at a specific wavelength λ was applied. This technique was demonstrated to be a powerful tool for basic research on intracellular structural analysis.

Noninvasive and safe cell viability assay for using natural food pigment.

Noninvasive and safe cell viability assay is required in many fields such as regenerative medicine, genetic engineering, single-cell analysis, and microbial food culture. In this case, a safe and inexpensive method which is a small load on cells and the environment is preferable without requiring expensive and space-consuming equipment and a technician to operate. We examined eight typical natural food pigments to find pigment (MP) or anthocyanin pigment (AP) works as a good viability indicator of dye exclusion test (DET) for which is an edible photosynthetic green microalga.

Hydrogen photoproduction in green algae Chlamydomonas reinhardtii sustainable over 2 weeks with the original cell culture without supply of fresh cells nor exchange of the whole culture medium.

Unicellular green algae Chlamydomonas reinhardtii are known to make hydrogen photoproduction under the anaerobic condition with water molecules as the hydrogen source. Since the hydrogen photoproduction occurs for a cell to circumvent crisis of its survival, it is only temporary. It is a challenge to realize persistent hydrogen production because the cells must withstand stressful conditions to survive with alternation of generations in the cell culture.

Scan-Free Absorbance Spectral Imaging A(x, y, λ) of Single Live Algal Cells for Quantifying Absorbance of Cell Suspensions.

Label-free, non-invasive, rapid absorbance spectral imaging A(x,y,λ) microscopy of single live cells at 1.2 μm × 1.2 μm resolution with an NA = 0.

Highly selective carboxylative cyclization of allenylmethylamines with carbon dioxide using N-heterocyclic carbene-silver(I) catalysts.

Silver(I) carboxylate complexes promote the carboxylative cyclization of allenylmethylamines to afford 5-alkenyl-1,3-oxazolidin-2-ones in 2-propanol. The use of an N-heterocyclic carbene ligand (IPr) under pressurized CO2 is effective in suppressing the intramolecular hydroamination that leads to 2,5-dihydropyrroles. The mechanism involving a nucleophilic attack of the carbamate of the allene moiety and a subsequent protonation was realized on the basis of experimental and theoretical results involving a model intermediate, the alkenylgold(I) complex, which was synthesized from Au(OH)(IPr) and 1-methylamino-2,3-butadiene.

Water adsorption-desorption isotherms of two-dimensional hexagonal mesoporous silica around freezing point.

Zr-doped mesoporous silica with a diameter of approximately 3.8 nm was synthesized via an evaporation-induced self-assembly process, and the adsorption-desorption isotherms of water vapor were measured in the temperature range of 263-298 K. The measured adsorption-desorption isotherms below 273 K indicated that water confined in the mesopores did not freeze at any relative pressure.