High-Speed Melt Spinning of Polylactide/Poly(Butyleneterephthalate) Bicomponent Fibers: Mechanism of Fiber Structure Development and Dyeing Behavior

Bicomponent fibers consisting of polylactide (PLA) as the sheath and poly(butylene terephthalate) (PBT) as the core were produced by high-speed spinning to obtain materials suitable for medical clothing. The higher-order structure of the PLA fiber component appeared to exhibit simple, alternately stacked, uniaxially oriented amorphous and crystalline regions. Therefore, fairly large tanδ peaks were observed for single-component PLA fibers, even when the orientation-induced crystallization was achieved by high-speed spinning. By conjugating PLA with PBT, although limited mutual interference with the crystallization of each component occurred, both the PLA (Mw?=?170,000, L-lactide content?=?98.7%) and PBT (intrinsic viscosity?=?0.835-0.865 dL/g) could crystallize on a high-speed spinning line, and the proposed formation of a shish-kebab-like structure in the PBT component enhanced the thermal stability of the bicomponent fibers, particularly resulting in shrink-proof properties. The bicomponent fibers developed herein could be deeply dyed at 98?°C, with results comparable to those of industrial polyester, and peeling of the PLA skin layer was rarely observed, even when the dyed fibers were flattened by a rubbing force.     

Synthesis, Reactivity, and Spectroscopic Properties of meso-Triaryl-5-oxaporphyrins

[meso-Triaryl-21,23-didehydro-23H-5-oxaporphyrinato](trifluoroacetato)zinc(II) was prepared by the reaction of meso-triarylbilindione with acetic anhydride and zinc acetate, and it was isolated as a trifluoroacetate salt. The X-ray crystallographic study demonstrated that the trifluoroacetate anion was coordinated to the zinc ion. [21,23-Didehydro-10,15,20-tris(4-methoxycarbonylphenyl)-23H-5-oxaporphyrinato](trifluoroacetato)zinc(II) 3a was dissolved in various organic solvents such as toluene, chloroform, diethyl ether, ethyl acetate, acetone, acetonitrile, methanol, DMSO, and DMF, although it readily reacted with alcohols and DMF to yield linear tetrapyrroles. The solubility of 3a in toluene was 4.2 ± 0.1 g dm(-3) at room temperature. 3a showed characteristic UV-vis absorption at 649 nm and fluorescence emission at 657 nm in chloroform. The fluorescence quantum yields of 3a, [21,23-didehydro-10,15,20-triphenyl-23H-5-oxaporphyrinato](trifluoroacetato)zinc(II) (3c), and [21,23-didehydro-10,15,20-tris(4-methoxyphenyl)-23H-5-oxaporphyrinato](trifluoroacetato)zinc(II) (3b) were 0.071, 0.071, and 0.050, respectively. Reaction of 3a with EtOH afforded the zinc complex of 19-ethoxybilinone, and it proceeded 2 orders of magnitude faster than that of [β-octaalkyl-21,23-didehydro-23H-5-oxaporphyrinato]zinc(II). The reaction with alcohols was sensitive to steric bulk of the alcohols; the rate of reaction with i-PrOH was 2700 times faster than that of t-BuOH at 303 K. The reaction of [meso-triaryl-21,23-didehydro-23H-5-oxaporphyrinato]zinc(II) with water proceeded 3 orders of magnitude slower than that with EtOH.     

Chemical synthesis of intentionally misfolded homogeneous glycoprotein: a unique approach for the study of glycoprotein quality control

Biosynthesis of glycoproteins in the endoplasmic reticulum employs a quality control system, which discriminates and excludes misfolded malfunctional glycoproteins from a correctly folded one. As chemical tools to study the glycoprotein quality control system, we systematically synthesized misfolded homogeneous glycoproteins bearing a high-mannose type oligosaccharide via oxidative misfolding of a chemically synthesized homogeneous glycopeptide. The endoplasmic reticulum folding sensor enzyme, UDP-glucose:glycoprotein glucosyltransferase (UGGT), recognizes a specific folding intermediate, which exhibits a molten globule-like hydrophobic nature.     

5+1] cycloaddition of C,N-cyclic N'-acyl azomethine imines with isocyanides

A catalyst-free [5 + 1] cycloaddition reaction between isocyanides and C,N-cyclic N'-acyl azomethine imines as the "isocyanophile" leading to novel heterocycles has been developed. These reactions proceeded quickly and cleanly to afford the corresponding imin-1,3,4-oxadiazin-6-one derivatives in high to excellent yields. A wide range of C,N-cyclic N'-acyl azomethine imines and isocyanides were applicable to this reaction.     

Deterioration of bulk heterojunction organic photovoltaic devices by a minute amount of oxidized fullerene

A chemical model of deterioration of a bulk heterojunction organic solar cell containing a photooxidized product of 1,4-bis(dimethylphenylsilylmethyl)[60]fullerene suggests that molecular oxygen degrades device performance by two mechanisms.     

Multielectron reduction of diazoalkane and azides via reversible cyclometalation in ditantalum complexes

Reactions of the cyclometalated hydride complexes with diazo and azide substrates are reported. While diazoalkane undergoes four-electron N-N bond cleavage, azides undergo two-electron N(2) extrusion.     

Partially saturated fluorinated heterocycles: diastereo- and enantioselective synthesis of β-trifluoromethyl-pyrroline carboxylates

The first asymmetric synthesis of β-trifluoromethylated pyrroline carboxylates has been achieved by organocatalytic conjugated addition of adamantyl glycine imine to β-trifluoromethylated enones, followed by a deprotection/cyclization/dehydration sequence.     

M?ssbauer study of contaminated soils by industrial activity in Paramonga city, Region Lima Provinces, Peru

In this work we characterize soils from the Paramonga city, Region Lima Provinces in Peru, which are contaminated by residual chemicals (Br, As and Sr) from sugar and paper industry in the city. Four samples were collected, labelled as S1, S2, S3 and S4 and analized by X-ray diffraction (XRD), energy-dispersive X-ray fluorescence (EDXRF) and M?ssbauer spectroscopy. For all the samples, the chemical analysis by EDXRF revealed the presence of Fe, Mn, Cu, Zn, K, Br, Sr. The XRD detected the presence of quartz as principal phase and copper sulfide and potassium magnesium as secondary phases. The M?ssbauer spectra at room temperature (RT) for all the samples exhibit sextets which reveal the presence of an iron oxide or hydroxide. The fitting M?ssbauer for both samples S1 and S4 have three doublets corresponding to iron in paramagnetic phases and a magnetic component of around 35.50?T corresponding to goethite, α-FeOOH. Sample S2 have two magnetic phases with internal fields of 37?T and 34.6?T which correspond to the goethite and other incorporated element in the structure. The sample S3 have three magnetic fields of H1?=?36.8?T, H2?=?33.6?T and H3?=?34.8?T which correspond to hydroxide iron, pyrrhotite and goethite respectively.     

A note on statistical model for BPS D4–D2–D0 states

We construct a statistical model that reproduces the BPS partition function of D4–D2–D0 bound states on a class of toric Calabi–Yau three-folds. The Calabi–Yau three-folds we consider are obtained by adding a compact two-cycle to _AN−1-ALE×C$A_{N-1}\text{-ALE}\times \mathbb{C}$. We show that in the small radii limit of the Calabi–Yau the D4–D2–D0 partition function is correctly reproduced by counting the number of triangles and parallelograms.     

Detection of water in organic solvents by photo-induced electron transfer method

A new class of fluorescence sensor for detection of water in organic solvents based on photo-induced electron transfer (PET) of anthracene coupled with an amino acid has been designed and developed.