Water absorption and maintenance of nanofiber cellulose production by Gluconacetobacter rhaeticus TL-2C

Physiochemical properties of bacterial cellulose producing by Gluconacetobacter rhaeticus TL-2C was investigated for confirming its possibility as wound care dressing material. Scanning electron micrograph showed that the diameter of bacterial cellulose fiber was 40 to 50 nm. Solid state 13C nuclear magnetic resonance (NMR) data showed that the bacterial cellulose had amorphous peak of C-4 and C-6 and the crystallinity index of bacterial cellulose was 75.4. Water absorption ability of bacterial cellulose was 19-fold higher than α-cellulose. Bacterial cellulose had 2-fold higher water maintenance ability than α-cellulose.Key words: Bacterial cellulose, Gluconacetobacter rhaeticus, nanofiber, water absorption

DECAY FACTOR WITH EXPERIMENTAL VARIABLES IN TWO CIRCULATING FLUIDIZED BED (CFB) RISERS

The effects of the riser inlet velocity, solid mass flux and particle size on the axial solid holdup profile and decay factor were investigated using two circulating fluidized beds (CFBs) with FCC (Geldart A) particles as the bed materials. Based on the experimental results from the two-CFBs, the axial solid holdup in the two CFBs were compared with the correlations of previous studies. Also, an empirical correlation was proposed for decay factor that exhibited a good agreement with experimental data

Characterization of single photon sources for radiometry applications at room temperature

A single photon source with high repeatability and low uncertainties is the key element for few-photon metrology based on photon numbers. While low photon number fluctuations and high repeatability are important figures for qualification as a standard light source, these characteristics are limited in single photon emitters by some malicious phenomena like blinking or internal relaxations to varying degrees in different materials. This study seeks to characterize photon number fluctuations and repeatability for radiometry applications at room temperature. For generality in this study, we collected photon statistics data with various single photon emitters of $g^{(2)}(0) < 1$ at low excitation power and room temperature in three material platforms: silicon vacancy in diamond, defects in GaN, and vacancy in hBN. We found common factors related with the relaxation times of the internal states that indirectly affect photon number stability. We observed a high stability of photon number with defects in GaN due to faster relaxations compared with vacancies in hBN, which on the other hand produced high rates ($> 10^6$) of photons per second. Finally, we demonstrate repeatable radiant flux measurements of a bright hBN single photon emitter for a wide radiant flux range from a few tens of femtowatts to one picowatt.Comment: Submitted to: Materials for Quantum Technology (IOP

Ubiquitous-Severance Hospital Project: Implementation and Results

OBJECTIVES: The purpose of this study was to review an implementation of u-Severance information system with focus on electronic hospital records (EHR) and to suggest future improvements. METHODS: Clinical Data Repository (CDR) of u-Severance involved implementing electronic medical records (EMR) as the basis of EHR and the management of individual health records. EHR were implemented with service enhancements extending to the clinical decision support system (CDSS) and expanding the knowledge base for research with a repository for clinical data and medical care information. RESULTS: The EMR system of Yonsei University Health Systems (YUHS) consists of HP integrity superdome servers using MS SQL as a database management system and MS Windows as its operating system. CONCLUSIONS: YUHS is a high-performing medical institution with regards to efficient management and customer satisfaction; however, after 5 years of implementation of u-Severance system, several limitations with regards to expandability and security have been identifiedope

Asymmetric catalytic reactions by NbO-type chiral metal-organic frameworks † ‡

Chiral metal-organic frameworks (MOFs) constitute a unique class of multifunctional hybrid materials and are envisioned as a versatile tool for various enantioselective applications, including the separation of optical isomers and the promotion of catalytic enantioselective reactions. Despite some pioneering works on catalytic enantioselective reactions promoted by chiral MOFs, there is still a need for practical catalysts and many fundamental issues must be answered; such as pin-pointing the site of the reaction and expedition of the reaction rate to the level of that in homogeneous media. We have designed and synthesized a chiral metal-organic framework, ( NbO type framework provides a spacious pore (2 Â 2 Â 2 nm 3 ) and is equipped with potential catalytic sites exposed into the pore. Since the functional group on the organic links, biphenols in this MOF, can be modified further on demand, this MOF can serve as a platform for new heterogeneous catalysis. Two reactions, the carbonyl-ene reaction with modified MOF after replacement of the protons on biphenol on the organic links with Zn(II) and the hetero-Diels-Alder reaction with Ti(IV), respectively, were studied. In this manoeuver, we observed that the reaction occurs entirely inside the pores and the reaction rate of the heterogeneous reaction by this specific MOF is comparable to that of its homogeneous counterpart. In addition, it is also observed that the enantioselectivities are significantly improved by extra steric bias provided from the frames of the MOF. These observations reinforce the legitimacy of the strategy of using a chiral MOF as a highly enantioselective heterogeneous catalyst