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In this study, poly(mandelate-co-glycolate) (PMG), a modified polyglycolide (PGL), is prepared by ring-opening polymerization (ROP) of L-3-phenyl-1,4-dioxane-2,5-dione (PDD); the cyclic dimer of biobased mandelic acid and glycolic acid. The resulting polymer shows an increased glass transition temperature (Tg ) due to the incorporation of phenyl groups in the chain. High molecular weight PMG is obtained by bulk ROP at 150 °C, and it exhibits a glassy amorphous state with enhanced thermal properties such as a Tg being 35 °C higher than conventional PGL. PDD is also copolymerized with glycolide (GL) and lactide (LA), resulting in poly(mandelate-co-glycolate/glycolate) ((P(MG/GL)) with GL and poly(mandelate-co-glycolate/lactide) ((P(MG/LA)) with LA. The thermal properties of P(MG/GL) and P(MG/LA) are found to be distinctly different from PMG and conventional PGL and polylactide, and they are tunable with a changing molar ratio of PDD, GL, and LA. Therefore, PDD opens an elegant way to control and tailor the properties of biobased polyesters.
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Glicolatos/química , Ácidos Mandélicos/química , Ácido Poliglicólico/química , Polimerização , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Dioxanos/química , Espectroscopia de Ressonância Magnética , Ácido Poliglicólico/síntese química , Polímeros/síntese química , Polímeros/química , Temperatura de TransiçãoRESUMO
We designed a new image scanner using the reflective optics of a compound eye system that can easily assemble plural imaging optical units (called imaging cells) and is compact with a large depth of field (DOF). Our image scanner is constructed from 32 reflective imaging cells, each of which takes an image of approximately a 10-mm field of view (FOV) that slightly overlap the adjacent imaging cells. The total image is rebuilt by combining the 32 images in post processing. We studied how to fold the optical path in the imaging cells and simplified the structure, resulting in the following three advances of our previous work: 1) greater compactness (50 × 31 mm2 in the cross section), 2) less variable optical characteristics among the imaging cells, and 3) easy assembly thanks to small number of optical components constructing the imaging cell.
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Both AB diblock and ABA triblock copolymers consisting of poly(L-lactide) (PLLA: A) and poly(ethylene glycol) (PEG: B) were deposited on a silicon surface on which poly(D-lactide) (PDLA) had been preimmobilized. The deposit of the diblock copolymer (PLLA-PEG) formed band structures similar to those observed when the same copolymer was directly deposited on the silicon surface. In contrast, the deposit of the triblock copolymer (PLLA-PEG-PLLA) formed many particulates scattering over the surface. When the PLLA-PEG deposit was subjected to water-soaking, the original band morphology was completely replaced by the particulate morphology that was identical to that of the PLLA-PEG-PLLA deposit. Their FT-IR analyses revealed that both copolymers had been bound through the stereocomplex (sc) formation between the preimmobilized PDLA chains and the PLLA blocks of the copolymers. Grazing-incidence small-angle X-ray scattering (GISAXS) also supported these surface morphologies. It was therefore evident that hydrophilic PEG chains can be immobilized on the PDLA-preimmobilized surface by the sc formation.
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Lactatos/química , Ácido Láctico/química , Modelos Químicos , Poliésteres/química , Polietilenoglicóis/química , Polímeros/química , Propriedades de SuperfícieRESUMO
This case highlights the necessity to inform patients with vein ligation about the possibility of varicose vein formation in the periphery and brings awareness to emergency staff that bleeding could be caused by a ruptured peripheral varicose vein.
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Aim: This study aimed to compare open abdominal management (OAM) between visible negative pressure wound therapy (NPWT) and commercial NPWT to determine whether NPWT can detect intestinal ischemia in its early stages without causing complications or worsening prognosis, and to determine whether the actual visualization results in early detection. Methods: Patients were divided into two groups: those who underwent OAM with visible NPWT (A: 32 patients) and those who underwent OAM with commercial NPWT (B: 12 patients). We compared background factors, disease severity, vital signs, blood test values, and 28-day outcomes between the two groups. We also checked the records to determine how many visualized cases were detected early and operated on. We then examined the weaknesses of this method. Results: No differences were observed in the background factors or disease severity between the two groups. The duration of the open abdomen and intensive care unit stay were significantly shorter for group A than for group B. The groups showed no significant differences in lactate levels, 28-day outcomes, complications during OAM, or other factors. After a review of the medical records, ischemic progression was detected early, and surgery could be performed in seven cases in the visible NPWT group. The progression of ischemia was confirmed at the time of the second-look operation in two cases in the ascending colon. Conclusion: The visualization device allowed us to gain insights into the intra-abdominal cavity and determine the appropriate time for closing the abdomen without worsening the prognosis.
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A compact image scanner is designed by using a compound eye system with plural optical units in which a ray path is folded by reflective optics. The optical units are aligned in two lines and take each image of a separated field of view (FOV), slightly overlapped. Since the optical units are telecentric in the object space and the magnification ratio is constant regardless of the object distance, the separated pieces of a total image are easily combined with each other even in the defocused position. Since the optical axes between adjacent optical units are crossed obliquely, object distance is derived from the parallax at each boundary position and an adequate deblurring process is achieved for the defocused image.
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Olho Composto de Artrópodes , Imageamento Tridimensional/instrumentação , Fenômenos Ópticos , Animais , Biomimética , Simulação por ComputadorRESUMO
Poly(D-lactide)s (PDLA) having an end group of trimethoxysilyl (P(x)-Si-(OMe)(3)) or monoethoxydimethylsilyl (P(x)-Si-OEt) group were synthesized to immobilize macromolecular chains of polylactide onto a flat silicon surface by the "grafting onto" mechanism. Both the end-functional PDLAs were efficiently immobilized on the flat surface of silicon wafers to create different nano-ordered structures. The P(x)-Si-OEt having the monofunctional siloxyl group formed a homogeneous dot morphology consisting of homogeneously dispersed particles of 20-30 nm in diameter while the P(x)-Si-(OMe)(3) having the trifunctional siloxyl group formed a heterogeneous morphology consisting of both spots and fibrous strands. The former homogeneous morphology was attributed to the lack of the intermolecular cross-linking reaction that was evident in P(x)-Si-(OMe)(3).
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Nanoestruturas/química , Poliésteres/síntese química , Siloxanas/síntese química , Microscopia de Força Atômica , Tamanho da Partícula , Poliésteres/química , Silanos/química , Silício/química , Siloxanas/química , Propriedades de Superfície , Temperatura de TransiçãoRESUMO
A novel polymer blend system consisting of poly(l-lactide) (PLLA) and a thermotropic liquid crystalline polymer (LCP: an aromatic polyester comprising poly(4-hydroxybenzoate) sequences) was investigated in the presence and absence of a polycabodiimide (PCD). Scanning electron micrographs of the injection-molded polymer blends revealed the formation of fibrous structure of LCP in the PLLA matrix, supporting the efficient toughening. In particular, the LCP fibrils became semimicrometer in diameter in the presence of PCD with which both PLLA and LCP had reacted during the melt blending to form their block and graft copolymers working as compatibilizer. The blend specimens containing LCP in 20-30 wt % were found to hold high dynamic storage-moduli (E') at high temperature. In addition, the E' value of the specimens containing 30 wt % of LCP reached 10.7 GPa at room temperature, being significantly higher than that of PLLA.
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Cristais Líquidos/química , Poliésteres/química , Temperatura , Teste de MateriaisRESUMO
Poly(ethylene 2,5-furandicarboxylate) (PEF) is regarded as a bio-based alternative or complementary polyester for the widely used fossil resource-based polyester, poly(ethylene terephthalate) (PET). High-speed melt spinning of PEF of low and high molecular weight (L-PEF, H-PEF) was conducted, and the structure and properties of the resultant as-spun fibers were investigated. The occurrence of orientation-induced crystallization was confirmed for the H-PEF at the take-up velocity of 6.0 km/min, the highest speed for producing PET fibers in the industry. Molecular orientation and crystallinity of the as-spun fibers increased with the increase of take-up velocity, where the H-PEF fibers always showed a higher degree of structural development than the L-PEF fibers. The tensile modulus of the high-speed spun H-PEF fibers was relatively low at 5 GPa, whereas a sufficiently high tensile strength of approximately 500 MPa was measured. These values are adequately high for the application in the general semi-engineering fiber field.
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The main motivation for development of biobased polymers was their biodegradability, which is becoming important due to strong public concern about waste. Reflecting recent changes in the polymer industry, the sustainability of biobased polymers allows them to be used for general and engineering applications. This expansion is driven by the remarkable progress in the processes for refining biomass feedstocks to produce biobased building blocks that allow biobased polymers to have more versatile and adaptable polymer chemical structures and to achieve target properties and functionalities. In this review, biobased polymers are categorized as those that are: (1) upgrades from biodegradable polylactides (PLA), polyhydroxyalkanoates (PHAs), and others; (2) analogous to petroleum-derived polymers such as bio-poly(ethylene terephthalate) (bio-PET); and (3) new biobased polymers such as poly(ethylene 2,5-furandicarboxylate) (PEF). The recent developments and progresses concerning biobased polymers are described, and important technical aspects of those polymers are introduced. Additionally, the recent scientific achievements regarding high-spec engineering-grade biobased polymers are presented.
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This study described the genetic map of tandem genes (est1 and est119) encoding cutinase-type polyesterases in Thermobifida alba AHK119 and comparison of wild type and mutant enzymes of Est1 and Est119. Two genes were independently and constitutively expressed. The activity of Est1 was higher by approximately 1.6-1.7-fold than that of Est119 towards p-nitrophenyl butyrate, although both enzymes shared 95% sequence identity and 98% similarity and possessed similar 3D structures except that several amino acids in the probable substrate-docking loops were different from each other. Calcium ion enhanced the activity and the thermostability of both enzymes. Based on conserved sequences among Thermobifida cutinases, valine, proline and lysine were introduced into Est1 at Ala68, Thr253 and Met256, respectively. Among wild and mutant enzymes of Est119 and Est1, Est1 (A68V/T253P) possessed three prolines in the substrate-docking loops and displayed the highest thermostability that spotlighted the important effect of proline numbers in the loops. Est1 (A68V/T253P) was stable for 1 h below 60°C and even at 65°C, more than 70% and 50% activities were maintained after 30 and 60 min, respectively. Est1 (A68V/T253P) degraded various aliphatic and aliphatic-co-aromatic polyesters and hydrophilized an amorphous PET film. The enzyme hydrolyzed a PET trimer model compound, indicating its specificity towards an ester bond between terephthalic acid and ethylene glycol.
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Actinomycetales/enzimologia , Actinomycetales/genética , Hidrolases de Éster Carboxílico/genética , Hidrolases de Éster Carboxílico/metabolismo , Sequência de Aminoácidos , Butiratos/metabolismo , Cálcio/farmacologia , Hidrolases de Éster Carboxílico/química , Sequência Conservada , Estabilidade Enzimática/efeitos dos fármacos , Genes Bacterianos/genética , Hidrólise , Dados de Sequência Molecular , Poliésteres/química , Poliésteres/metabolismo , Especificidade por Substrato , TemperaturaRESUMO
A quantitative and chemical assay of cereulide produced in the cultures by some strains of Bacillus cereus was performed on a HPLC and a ESI electrospray ion trap mass analyzer, using the synthetic cereulide as a standard. All 20 strains of emetic B. cereus were found to produce 27 - 740 ng/ml of cereulide by the LC-MS analysis. In contrast, none of the 10 diarrheal strains produced it. 10(2) cfu/ml of the cereulide producible strain with a 210 ng/ml yield was inoculated into the 10% suspensions of 14 food products, and was incubated at 32°C for 24h. The B. cereus counts in the cultures grew in the order of 10(8) to 10(9) cfu/ml, although the bacteria could not grow in fruits, and the yields of cereulide ranged from 5.18µg in curry to 0.03µg/g of raw material and/or powder material, except for fruits. These culture supernatants were also tested for the biological activity in the HEp-2 cell culture assay. Consequently, a certain correlation was shown between the yields of cereulide and the HEp-2 vacuolation activities. In addition, the supernatants were administered i.p. to 5 Suncus marinus test animals. The emetic dose was calculated to be approximately 16µg/kg.
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Bacillus cereus/metabolismo , Técnicas de Química Analítica , Cromatografia Líquida/métodos , Depsipeptídeos/análise , Eméticos/análise , Microbiologia de Alimentos , Espectrometria de Massas/métodos , Animais , Linhagem Celular , Depsipeptídeos/toxicidade , Eméticos/toxicidade , Hepatócitos/efeitos dos fármacos , HumanosRESUMO
Lactic acid bacteria were isolated from various food samples and evaluated for hydrogen peroxide (H2O2) production. Cells suspended in 0.5% (wt/vol) glucose plus 0.5% (wt/vol) lactate (pH 7.0) were incubated for 5 h at 37 degrees C under aeration. Among 193 strains, 27 strains accumulated 201-300 ppm H2O2, and 4 strains accumulated more than 301 ppm H2O2 in the cell suspensions. Among the 9 high-level H2O2-producing strains, 8 strains were identified as Lactococcus lactis subsp. lactis. The cell-free filtrate from Lc. lactis subsp. lactis AI 62, which contained approximately 350 ppm H2O2, was evaluated for antimicrobial activity against Enterococcus faecalis, Ent. faecium, enterotoxigenic Escherichia coli, Listeria ivanovii, Staphylococcus aureus, Yersinia enterocolitica, and Aeromonas hydrophila. After 1 h incubation at 30 degrees C in the cell-free filtrate, the initial viable cell counts of the target bacteria (5.53-6.00 log cfu/mL) were reduced by 0.12-5.00 log units, except in the case of enterococci. The sensitivity varied with the bacterial species and pH. The enterococci were resistant to the treatment. Our results show that H2O2 accumulated by lactic acid bacteria in a cell suspension is very effective in reducing the viable cell count of food-borne pathogens.