Analysis of Chain Branch of Polyolefins by a New Proton NMR Approach.

The crystallinity of polyethylene, which significantly affects the properties of the polymer, is quite sensitive to the concentration of its branches. Thus, it is necessary to estimate branch concentration with reasonable accuracy. Currently, (13)C NMR and gel permeation chromatography-Fourier transform infrared spectroscopy are widely-used analysis methods for the analysis of branch concentration. Despite several advantages, these methods sometimes have limitations. For instance, the preparation of samples for (13)C- NMR is tedious because high-concentration samples are required and the time for analysis is greater than 12 h. To more efficiently estimate the branch concentration of polyethylene, we developed a new high-field (1)H NMR method with an improved peak resolution by employing (1) homonuclear decoupling and (2) 2D heteronuclear correlation. The new method was observed to significantly reduce the experimental time to ∼ 30 min; furthermore, sample preparation was relatively simple because the method did not require high-concentration samples.

Enhanced production of protease by Pseudoalteromonas arctica PAMC 21717 via statistical optimization of mineral components and fed-batch fermentation.

The objective of this study was to statistically optimize the mineral components of the nutritional medium required for enhancing the production of a cold-active extracellular serine-type protease, W-Pro21717, by the Antarctic bacterium Pseudoalteromonas arctica PAMC 21717. Skim milk was identified as the major efficient inducer. Among the 12 components included in the unoptimized medium, skim milk, NaCl, Na2SO4, Fe(C6H5O7) (ferric citrate), and KCl were determined, by the Plackett-Burman and Box-Behnken design, to have a major effect on W-Pro21717 production. Fed-batch fermentation (5 L scale) using the mineral-optimized medium supplemented with concentrated skim milk (critical medium component) resulted in a W-Pro21717 activity of 53.4 U/L, a 15-fold increment in production over that obtained using unoptimized flask culture conditions. These findings could be applied to scale up the production of cold-active protease.

Correlation between trunk rotation and lateral flexion range of motion, peak cough flow, and chest expansion in stroke patients.

INTRODUCTION: Stroke patients have problems with voluntary movement and trunk control. Moreover, the respiratory function in stroke patients is affected by neurological impairment, which increases the incidence of respiratory complications. OBJECTIVES: To determine the correlation between trunk rotation range of motion (TRROM) and trunk lateral flexion range of motion (TLFROM), peak cough flow (PCF), and chest expansion in stroke patients. METHODS: This was an observational study involving 21 patients with a clinical diagnosis of stroke from October 2021 to January 2022. TRROM and TLFROM were assessed using smartphone applications (Compass and Clinometer), respectively, PCF was assessed using a peak flow meter, and chest expansion was assessed using a tape measure. Pearson's correlation was used to analyze the relationships between the variables. RESULTS: Statistically significant correlations were found between TRROM and TLFROM (r = 0.91, p < 0.01) and between upper chest expansion and PCF (r = 0.59, p < 0.01). There were significant correlations between lower chest expansion and TRROM (r = 0.50, p < 0.05) and between lower chest expansion and TLFROM (r = 0.51, p < 0.05). CONCLUSION: This study demonstrates the relationship between upper chest expansion and PCF. Upper chest expansion exercises should be considered to improve the PCF in stroke patients. In addition, a very strong positive correlation between TRROM and TLFROM was demonstrated. TRROM and TLFROM exercises should be considered to improve the lower chest expansion in stroke patients.

Respiratory Parameters as Predictors of Balance and Gait Ability in Patients with Stroke at Discharge.

Pulmonary complications are frequent in stroke, contributing to both mortality and morbidity rates. Respiratory parameters in such patients encompass both pulmonary function and respiratory muscle strength. Identifying respiratory function variables that influence the balance and gait ability of patients with stroke is crucial for enhancing their recovery in these aspects. However, no study has assessed predictions for a comprehensive array of balance and gait abilities in such patients. We aimed to examine whether initial respiratory muscle strength and pulmonary function can predict balance and gait ability at discharge from a rehabilitation program. Thirty-one patients with stroke were included in this prospective observational study. Multiple regression models with a forward selection procedure were employed to identify respiratory parameters (including peak expiratory flow and maximal expiratory pressure) that contributed to the results of balance assessments and gait evaluations at the time of discharge. The peak expiratory flow (PEF) served as a predictor explaining 42.0% of the variance. Similarly, the maximal expiratory pressure (MEP) was a predictor variable explaining 32.0% of the variance. PEF and MEP assessments at the initial stage as predictive factors for both balance and gait ability are important in stroke management.

Optimization of cold-active chitinase production from the Antarctic bacterium, Sanguibacter antarcticus KOPRI 21702.

In the present study, cultivation conditions and medium components were optimized using statistical design and analysis to enhance the production of Chi21702, a cold-active extracellular chitinase from the Antarctic bacterium Sanguibacter antarcticus KOPRI 21702. Identification of significant carbon sources and other key elements was performed using a statistical design technique. Chitin and glycerol were selected as main carbon sources, and the ratio of complex nitrogen sources to carbon sources was determined to be 0.5. Among 15 mineral components included in basal medium, NaCl, Fe(C6H5O7), and MgCl2 were found to have the most influence on Chi21702 production. The optimal parameters of temperature, initial pH, and dissolved oxygen level were found to be 25°C, 6.5, and above 30% of air saturation, respectively. The maximum Chi21702 activity obtained under the optimized conditions was 90 U/L. Through statistical optimization methods, a 7.5-fold increase in Chi21702 production was achieved over unoptimized conditions. Chi21702 showed relatively high activity, even at low temperatures close to 0°C. The information obtained in the present study could be applied to the production of cold-active endochitinase on a large scale, suitable for a process at low temperature in industry.

Expression of recombinant endochitinase from the Antarctic bacterium, Sanguibacter antarcticus KOPRI 21702 in Pichia pastoris by codon optimization.

An endochitinase was previously purified and the gene was cloned from the psychrophilic Antarctic bacterium, Sanguibacter antarcticus (KCTC 13143). In the present study, recombinant endochitinase, rChi21702, was expressed using a yeast expression system (Pichia pastoris) and codon optimization. The expressed rChi21702 was purified by Phenyl-Sepharose column chromatography. Optimal expression yielded 1-mg purified enzyme from 1-L bioreactor culture. When p-NP-(GlcNAc)(2) was used as a substrate, the specific activity of the enzyme was determined to be 20U/mg. In vitro assays and thin-layer chromatography demonstrated that the recombinant enzyme has endochitinase activity that produces diacetyl-chitobiose as a dominant end product when chitooligomers, colloidal chitin, and the chromogenic p-NP-(GlcNAc)(2) are used as substrates. Optimal activity for rChi21702 was observed at 37 degrees C and a pH of 7.6. Interestingly, rChi21702 exhibited 63% of optimal activity at 10 degrees C and 44% activity at 0 degrees C. Taken together, the results indicate that rChi21702 has psychrotolerant endochitinase activity even after recombinant expression in yeast cells.

Heteronuclear cross-relaxation effect modulated by the dynamics of N-functional groups in the solid state under 15N DP-MAS DNP.

In a typical magic-angle spinning (MAS) dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) experiment, several mechanisms are simultaneously involved when transferring much larger polarization of electron spins to NMR active nuclei of interest. Recently, specific cross-relaxation enhancement by active motions under DNP (SCREAM-DNP) [Daube et al. JACS 2016] has been reported as one of these mechanisms. Thereby 13C enhancement with inverted sign was observed in a direct polarization (DP) MAS DNP experiment, caused by reorientation dynamics of methyl that was not frozen out at 100 K. Here, we report on the spontaneous polarization transfer from hyperpolarized 1H to both primary amine and ammonium nitrogens, resulting in an additional positive signal enhancement in the 15N NMR spectra during 15N DP-MAS DNP. The cross-relaxation induced signal enhancement (CRE) for 15N is of opposite sign compared to that observed for 13C due to the negative sign of the gyromagnetic ratio of 15N. The influence on CRE efficiency caused by variation of the radical solution composition and by temperature was also investigated.

Selection of Lecanicillium Strain with High Virulence against Developmental Stages of Bemisia tabaci.

Selection of fungal strains with high virulence against the developmental stages of Bemisia tabaci was performed using internal transcribed spacer regions. The growth rate of hyphae was measured and bioassay of each developmental stage of B. tabaci was conducted for seven days. All of the fungal strains tested were identified as Lecanicillium spp., with strain 4078 showing the fastest mycelium growth rate (colony diameter, 16.3 ± 0.9 mm) among the strains. Compared to strain 4075, which showed the slowest growth rate, the growth rate of strain 4078 was increased almost 2-fold after seven days. Strains 4078 and Btab01 were most virulent against the egg and larva stages, respectively. The virulence of fungal strains against the adult stage was high, except for strains 41185 and 3387. Based on the growth rate of mycelium and level of virulence, strains 4078 and Btab01 were selected as the best fungal strains for application to B. tabaci, regardless of developmental stage.