Denaturation temperature of dried lens tissue rises with trehalose pretreatment

Trehalose, a non-reducing disaccharide, is known as an exceptional protector against desiccation and heat stress. Differential scanning calorimetry is a simple tool to determine thermodynamic parameters concerning the structural state of proteins. In this study, we measured denaturation temperature (or melting temperature) of dried lenses to know the effect of trehalose pretreatment. Isolated porcine lenses were incubated in wells without any solution or with saline, 100 mM trehalose, or 100 mM cyclic tetrasaccharide in saline at room temperature for 150 min. The solutions were removed, and all lens samples were dried at room temperature and in room humidity until the weight showed no change. The nucleus of each sample was taken out and placed on a measuring platform for differential scanning calorimetry. The denaturation temperature of the dried lenses significantly rose by about 10 °C with 100 mM trehalose pretreatment, compared to no pretreatment, pretreatment with saline or 100 mM cyclic tetrasaccharide (P < 0.05, analysis of variance, P < 0.05, Student–Newman–Keuls tests, n = 7). The denaturation temperature showed no difference among the dried lenses with no pretreatment or pretreatment by saline or cyclic tetrasaccharide. In conclusion, pretreatment with trehalose raises denaturation temperature of the dried porcine lens. Trehalose might stabilize the dried tissue structure to get a higher denaturation temperature.     

Reconstruction of the signal produced by a directional sound source from remote multi-microphone recordings

A mathematical method for reconstructing the signal produced by a directional sound source from knowledge of the same signal in the far field, i.e., microphone recordings, is developed. The key idea is to compute inverse filters that compensate for the directional filtering of the signal by the sound source directivity, using a least-square error optimization strategy. Previous work pointed out how the method strongly depends on arrival times of signal in the microphone recordings. Two strategies are used in this paper for calculating the time shifts that are afterward taken as inputs, together with source directivity, for the reconstruction. The method has been tested in a laboratory environment, where ground truth was available, with a Polaroid transducer as source. The reconstructions are similar with both strategies. The performance of the method also depends on source orientation.     

Thermal Treatment of Ultrathin Pentacene Thin-Film Transistors

Structural properties and influence of thermal treatment on electrical properties for organic thin-film transistor (OTFT) with 3 nm-thickness active layer pentacene were investigated. The pentacene film was preferentially oriented to (00l) of thin-film phase and carriers conducted thought standing molecules slantingly. The carrier mobility of the ultrathin OTFT was decreased, and the threshold voltage was shifted to negative direction by thermal treatment. For the ultrathin OTFT, the carrier conduction was affected by H₂O and O₂ because of change in the interface state and the hole localization state by adsorption of O₂ and H₂O and oxidation.     

Lewis acid-catalyzed intermolecular [4 + 2] cycloaddition of 3-alkoxycyclobutanones to aldehydes and ketones

Intermolecular [4 + 2] cycloaddition between 3-alkoxycyclobutanones and aldehydes or ketones by the activation with boron trifluoride etherate is reported. The carbonyl compounds are inserted into the less substituted C2-C3 bond of the cyclobutanone ring of 6-alkyl-2-oxabicyclo[4.2.0]octan-7-ones to afford 1-alkyl-5,7-dioxabicyclo[4.4.0]decan-2-one derivatives regioselectively (>99:1) and diastereoselectively. On the other hand, [4 + 2] cycloaddition of 3-ethoxy-2,2-dialkylcyclobutanones at low temperature proceeds at the more substituted C2-C3 bond to yield 3,3-dialkyl-6-ethoxy-2,3,5,6-tetrahydro-4H-pyran-4-one derivatives with high regioselectivities. This [4 + 2] cycloaddition is developed into a one-pot synthesis of tri- or tetrasubstituted dihydro-gamma-pyrones from 3-ethoxycyclobutanones which are readily prepared from acid chloride and ethyl vinyl ether. The two regioselectivities observed in ring-opening of cyclobutanones can ascribe to thermodynamic stabilities of zwitterionic intermediates generated from tetrahydropyran-fused cyclobutanones and 3-ethoxycyclobutanones.     

Regioselective synthesis of 1,4-di(organo)[60]fullerenes through DMF-assisted monoaddition of silylmethyl Grignard reagents and subsequent alkylation reaction

Monoaddition of Grignard reagents, in particular tri(organo)silylmethylmagnesium chlorides, to [60]fullerene took place smoothly in the presence of dimethylformamide to produce (organo)(hydro)[60]fullerenes, C60R(1)H, in good yield (up to 93% isolated yield). The hydrofullerene was then deprotonated to generate the corresponding anion, C60R(-), which was then alkylated to obtain 58pi-electron di(organo)[60]fullerenes, C60R(1)R(2), in good to high yield (up to 93% overall yield). The two-step methodology provides a wide variety of 1,4-di(organo)[60] fullerenes bearing the same or different organic addends on the [60] fullerene core. By changing the addends, one can control the chemical and physical properties of the compounds at the molecular and bulk levels.     

Preparation of silylated magadiite thin-film-containing covalently attached pyrene chromophores

Thin-film of magadiite (Mag) silylated by [2-(perfluorohexyl)-ethyl]trichlorosilane was prepared by casting the chloroform/ethylacetate nanosheet solution of it. The addition of alkylamine and perfluoroalkyl groups to silylated magadiite greatly changed the surface morphology of the resulting sample and the transparent thin-film with relatively smooth surface was obtained. Amino groups were introduced into it by using 3-aminopropyltriethoxysilane after removal of alkylamine. The reaction of 1-pyrenebutanoic acid succimidyl ester with the thin-film of silylated magadiite-containing amino groups in N,N-dimethylforamide (DMF) resulted in the covalent attachment of pyrene chromophores to it.     

A new synthesis of potent antitumor saponin OSW-1 via Wittig rearrangement

OSW-1 and its analogues in which thiophene ring was introduced at the side chain were synthesized employing Wittig rearrangement of 17E(20)-ethylidene-16α-(4′-methyl-2′-thienyl)methyloxy steroid. The synthesis required nine steps from the known 17E(20)-ethylidene-16α-hydroxy steroid in 15.6% overall yield.     

Synthesis of Closed-Heterohelicenes Interconvertible between Their Monomeric and Dimeric Forms

Oxidative fusion reaction of cyclic heteroaromatic pentads consisting of pyrrole and thiophene gave closed-heterohelicene monomers and dimers depending on the oxidation conditions. Specifically, oxidation with [bis(trifluoroacetoxy)iodo]benzene (PIFA) gave closed-[7]helicene dimers connected at the β-position of one of the pyrrole units with remarkably elongated C−C bonds of about 1.60 Å. Although this bond was intact against thermal and physical activations, homolytic bond dissociation took place in DMSO upon irradiation with UV light to give the corresponding monomers. Thus, interconversion between the closed-helicene monomer and dimer was achieved. The optically pure dimer was photo-dissociated into the monomers associated with a turn-on of circularly polarized luminescence (CPL).     

Photoluminescence properties of Ag2S semiconductor clusters synthesized in micropores and mesopores

Silver sulfide (Ag₂S) clusters were synthesized in microporous zeolites and mesoporous AlMCM-41 by the sulfurization of Ag⁺ ions exchanged within the pores of the host. Characterization was performed by means of XRD, UV-Vis Ag K-edge XAFS and photoluminescence. The pore size of the host has great effects on the photoluminescence properties. Ag₂S/AlMCM-41 showed photoluminescence at the longer wavelengths than Ag₂S/zeolites. The photoluminescence band of Ag₂S in the zeolite with 1-dimensional channels was narrow in comparison to the Ag₂S in zeolites with 2- or 3-dimensional channels.     

Photocatalytic hydrogen generation using a protein-coated photosensitizer with anionic patches and a monocationic electron mediator

A reconstituted myoglobin with a synthetic cofactor having anionic binding sites effectively works as a photocatalyst for hydrogen generation in the presence of monomethylated bipyridinium.