13 research outputs found
Organic carboxylate salt-enabled alternative synthetic routes for bio-functional cyclic carbonates and aliphatic polycarbonates
Simple and efficient synthetic routes for functionalized cyclic carbonates are indispensable for the practical application of side-chain bio-functionalized aliphatic polycarbonates as biodegradable functional biomaterials. In this study, a six-membered cyclic carbonate with a triethylammonium carboxylate has been prepared in one step from 2,2-bis(methylol)propionic acid (bis-MPA). We have demonstrated the suitability of the organic carboxylate salt of the bis-MPA cyclic carbonate for esterification with alkyl bromides via the SN2 mechanism, leading to the formation of functionalized cyclic carbonate monomers. The esterification of the organic carboxylate salt proceeds efficiently when alkyl bromides with α-carbonyl, allyl, and benzyl groups are used. This approach enables a two-step synthesis of functionalized cyclic carbonates from bis-MPA. The organocatalyzed ring-opening polymerization of the resultant functionalized cyclic carbonates is effectively controlled, indicating that the synthetic process involving the organic carboxylate salt does not influence their polymerizability. The ether-functionalized aliphatic polycarbonates obtained from the organic carboxylate salt exhibit good antiplatelet properties, comparable to those of a previously developed blood-compatible aliphatic polycarbonate. The synthetic pathways exploiting organic carboxylate salts enable alternative shortcuts to functionalized cyclic carbonates from bis-MPA
Forgeability of AZ Series Magnesium Alloy produced by Twin Roll Casting
Plastic forming of magnesium alloy is hardly reported because of its low forgeability. The productions of magnesium alloy are mainly produced by casting. Typical wrought magnesium alloy is AZ31. Magnesium-aluminum alloy indicates maximum elongation when the composition includes 3% aluminum. When the magnesium alloy includes over 3% aluminum, its elongation slightly decreases. Therefore, AZ31 that include 3% aluminum and 1% zinc is generally used for plastic forming. The more increasing aluminum composition, the larger 0.2% proof stress becomes. However its forgeability is decreasing because of precipitation of β phase such as Mg17Al12. It is supposed that the β phase is refined by rapid cooling casting process such as twin roll casting. In this paper, the magnesium alloy thick sheet of AZ91, AZ121 and AZ131 for hot forging, that include 9%, 12% and 13% aluminum composition respectively, was produced by twin roll strip casting process. And the forgeability of high aluminum containing magnesium alloy was investigated by die forging. As a result, it was possible to forge their magnesium alloys
Lymphoepithelioma-like hepatocellular carcinoma: a case report and a review of the literature
Building a Scalable Web Tracking Detection System: Implementation and the Empirical Study
Development of Minimally Invasive Medical Tools Using Laser Processing on Cylindrical Substrates
Immaturin-Nuclease as a Model System for a Gene-Programmed Sexual Development and Rejuvenescence in <i>Paramecium</i> Life History
Fertilization-initiated development and adult-onset aging are standard features in the life history of eukaryotes. In Paramecium, the number of cell divisions after the birth of a new generation is an essential parameter of sexual phase transition and aging. However, the gene driving this process and its evolutionary origin have not yet been elucidated. Here we report several critical outcomes obtained by molecular genetics, immunofluorescence microscopy, transformation by microinjection, and enzymological analysis. The cloned immaturin gene induces sexual rejuvenation in both mature and senescent cells by microinjection. The immaturin gene originated from proteobacteria’s glutathione-S-transferase (GST) gene. However, immaturin has been shown to lose GST activity and instead acquire nuclease activity. In vitro substrates for immaturin-nuclease are single- and double-stranded DNA, linear and circular DNA, and single-stranded viral genome RNA such as coronavirus. Anti-immaturin antibodies have shown that the subcellular localizations of immaturin are the macronucleus, cytoplasm, cell surface area, and cilia. The phase transition of sexuality is related to a decrease in the intracellular abundance of immaturin. We propose that sexual maturation and rejuvenation is a process programmed by the immaturin gene, and the sexual function of each age is defined by both the abundance and the intracellular localization mode of the immaturin-nuclease
Monoether-Tagged Biodegradable Polycarbonate Preventing Platelet Adhesion and Demonstrating Vascular Cell Adhesion: A Promising Material for Resorbable Vascular Grafts and Stents
We
developed a biodegradable polycarbonate that demonstrates antithrombogenicity
and vascular cell adhesion via organocatalytic ring-opening polymerization
of a trimethylene carbonate (TMC) analogue bearing a methoxy group.
The monoether-tagged polycarbonate demonstrates a platelet adhesion
property that is 93 and 89% lower than those of poly(ethylene terephthalate)
and polyTMC, respectively. In contrast, vascular cell adhesion properties
of the polycarbonate are comparable to those controls, indicating
a potential for selective cell adhesion properties. This difference
in the cell adhesion property is well associated with surface hydration,
which affects protein adsorption and denaturation. Fibrinogen is slightly
denatured on the monoether-tagged polycarbonate, whereas fibronectin
is highly activated to expose the RGD motif for favorable vascular
cell adhesion. The surface hydration, mainly induced by the methoxy
side chain, also contributes to slowing the enzymatic degradation.
Consequently, the polycarbonate exhibits decent blood compatibility,
vascular cell adhesion properties, and biodegradability, which is
promising for applications in resorbable vascular grafts and stents
Deep Learning-enabled Detection and Classification of Bacterial Colonies using a Thin Film Transistor (TFT) Image Sensor
Early detection and identification of pathogenic bacteria such as Escherichia
coli (E. coli) is an essential task for public health. The conventional
culture-based methods for bacterial colony detection usually take >24 hours to
get the final read-out. Here, we demonstrate a bacterial colony-forming-unit
(CFU) detection system exploiting a thin-film-transistor (TFT)-based image
sensor array that saves ~12 hours compared to the Environmental Protection
Agency (EPA)-approved methods. To demonstrate the efficacy of this CFU
detection system, a lensfree imaging modality was built using the TFT image
sensor with a sample field-of-view of ~10 cm^2. Time-lapse images of bacterial
colonies cultured on chromogenic agar plates were automatically collected at
5-minute intervals. Two deep neural networks were used to detect and count the
growing colonies and identify their species. When blindly tested with 265
colonies of E. coli and other coliform bacteria (i.e., Citrobacter and
Klebsiella pneumoniae), our system reached an average CFU detection rate of
97.3% at 9 hours of incubation and an average recovery rate of 91.6% at ~12
hours. This TFT-based sensor can be applied to various microbiological
detection methods. Due to the large scalability, ultra-large field-of-view, and
low cost of the TFT-based image sensors, this platform can be integrated with
each agar plate to be tested and disposed of after the automated CFU count. The
imaging field-of-view of this platform can be cost-effectively increased to
>100 cm^2 to provide a massive throughput for CFU detection using, e.g.,
roll-to-roll manufacturing of TFTs as used in the flexible display industry.Comment: 18 Pages, 6 Figure