New Dual Initiators for Polyisobutylene-Based Block and Star Polymers

Polyisobutylene (PIB), available solely by living carbocationic polymerization (LCP), is a commercially important polymer with excellent thermal stability, good flexibility and extraordinary impermeability to gases. Due to these attractive properties, coupling PIB to other polymer blocks is expected to result in new and useful products. Two types of new dual initiators possessing initiating sites for both LCP and atom transfer radical polymerization (ATRP), have been designed for the preparation of AB linear and A2B miktoarm star copolymers, where A is PIB-based block copolymer that grows cationically and B is polyacrylate or other radically-derived polymer block, without intermediate modification. Mono-cationic mono-radical dual initiators, 3,3,5-trimethyl-5-chlorohexyl 2- bromopropionate (IB2BP) and 3,3,5-trimethyl-5-chlorohexyl 2-bromo-2- methylpropionate (IB2BMP) were synthesized and used to prepare AB linear polymers. PIBs obtained from both initiators showed high efficiency in ATRP initiations of methyl acrylate (MA), yielding polymers with targeted block length and narrow polydispersity index (PDI). However, IB2BMP and IB2BP displayed slow cationic initiation of isobutylene (IB) leading to moderate initiation efficiencies (0.50 \u3c Ieff \u3c 0.80) at low temperature (-70 °C) and low monomer/initiator ratio (82). 3,3,5,5,7-Pentamethyl-7- chlorooctyl 2-bromo-2-methylpropionate (IB3BMP), which differs from IB2BMP by the inclusion of one additional isobutylene (IB) repeating unit, was then synthesized. It showed quantitative initiation efficiency (Ieff ~1) in TiCl4-co-initiated LCP of IB under various reaction conditions. Ieff and PDI of the resulting PIBs were identical to those obtained with the standard mono-cationic initiators. The superiority of IB3BMP compared to IB2BMP in carbocationic initiation was attributed to elimination of through-space interactions between the tert-chloride initiating site and the TiCl4:carbonyl complex at the ATRP initiating site. Di-cationic mono-radical dual initiator 3-[3,5-bis(1-chloro-1- methylethyl)phenyl]-3-methylbutyl 2-bromo-2-methylpropionate (DCCBMP) was syntheized for the preparation of miktoarm star copolymers. Initiation efficiency of DCCBMP was high (0.89 \u3c Ieff \u3c 0.98) for LCP of IB and it was comparable to the standard di-cationic initiator. Using sequential monomer addition under LCP conditions, narrow-polydispersity poly(styrene-b-isobutylene-b-styrene) (PS-PIB-PS) triblock copolymers were prepared, yielding poly(acrylic acid-b-styrene-b-isobutylene)2- s-poly(acrylic acid) [(PAA-PS-PIB)2-s-PAA] amphiphilic miktoarm star polymer after ATRP of tert-butyl acrylate (tBA) and thermolysis of poly(tert-butyl acrylate) (PtBA) block. Upon thermolyzing PS-PIB-PS macroinitiator, poly(styrene-b-isobutylene)2-spoly( acrylic acid) [(PS-PIB)2-s-PAA] stars were obtained in the same manner

A comparative study of HPLC-DAD and UPLC-UV methods for simultaneous determination of 11 polyphenols in Moringa oleifera leaves

Purpose: To develop, validate and compare two chromatographic methods - high performance liquid chromatography with diode array detector ((HPLC-DAD) and high performance liquid chromatography with ultraviolet detection (UPLC-UV) for the effective analysis of polyphenols in Moringa oleifera leaves.Methods: HPLC-DAD and UPLC-UV methods were applied for the accurate determination of eleven major polyphenols in Moringa oleifera leaves. The chromatographic conditions of the eleven polyphenols was determined on two C18 column by gradient elution with 0.5 % phosphoric acid solution -acetonitrile as the eluate, and at a flow rate of 1.0 and 0.5 mL/min for HPLC-DAD and UPLC-UV methods, respectively. Detector parameter of UPLC-UV was fixed at 203 nm. The assay methods were validated systematically.Results: The instrumental methods (HPLC-DAD and UPLC-UV) had good linearity, precision,repeatability and recovery. For both methods, quantification limits of UPLC-UV (0.057 - 0.363 μg/mL) were lower than those of UPLC-UV (0.094 - 1.532 μg/mL). The UPLC method with a shorter running time and more sensitive detection was applied in comparing to the HPLC method. After optimization and evaluation, the baseline of 11 compounds was separated effectively within 68 and 34 min, respectively.Conclusion: The developed HPLC-DAD and UPLC-UV assays were successfully utilized for thesimultaneous analysis of eleven major polyphenols and can readily be utilized as quality control tools for Moringa oleifera leaves in China, with UPLC-UV method showing better separation, lower organic solvent usage and shorter analytical period

Seismic Anisotropy Estimation Using a Downhole Microseismic Data Set in a Shale Gas Reservoir

Shale anisotropy has a significant impact on the data processing and interpretation of microseismic monitoring in shale gas reservoirs. A geology- and rock-physics-constrained approach to estimating shale anisotropy using down-hole microseismic data sets is proposed in this study and is applied to the case of Horn River shale. A priori knowledge of shale anisotropy is obtained by integrating geological analyses and rock physics studies. This knowledge serves as an important constraint when building the initial model, minimizing the uncertainties and evaluating the results. The application to Horn River shale shows that the optimized anisotropic velocity model reduces the time misfit by about 65% compared to the originally provided velocity model. As the relocated perforation shot indicates, the event locations are significantly improved. The results also show that a high fraction of clay mineral results in strong fabric anisotropy in the Fort Simpson formation, whereas the quartz-rich shale gas reservoirs (Muskwa and Otter Park formations) show weaker fabric anisotropy. The percentage of velocity anisotropy in Horn River shale can be up to 40%. The fabric anisotropy of shale derived from the downhole microseismic data set is comparable with that of laboratory experiments. This demonstrates that downhole microseismic monitoring, as a quasi in situ experiment, has the potential to contribute to a better understanding of subsurface anisotropy beyond the laboratory. In addition, microseismic measurements of shale anisotropy are conducted in the seismic frequency band and are thus more applicable for further seismic applications

3D Reconstruction of Images Based on Embedded Processors

3D image reconstruction has very important value in reality. In this paper, based on embedded system, we use Marching Cubes algorithm to realize 3D image reconstruction and furthermore, display the result in web page. By introducing principle and whole process of reconstruction, we can prove that comparing with personal computer, this method has advantage of lower price, small volume, and has good prospect in future

Pengaruh Budaya Organisasi Terhadap Kinerja Karyawan (Studi Pada Karyawan PT. Sejahtera Buana Trada Surabaya)

The culture of the organization is to be considered in a company because it can affect the performance of the employee. Employees can work well if created a good culture and will infect other employees. This study is the explanation (explanatory research) with quantitative approach. The number of respondents in this study were 114 respondents who are employees of PT. Buana Sejahtera Trada Surabaya. The results showed a significant effect simultaneously (together) between the independent variables (Culture Orgaznisasi) affect the dependent variable (Employee Performance) So it can be concluded that the organizational culture can influence employee performance in carrying out its work

Prognostic risk of immune-associated signature in the microenvironment of brain gliomas

Understanding the key factors in the tumor microenvironment (TME) that affect the prognosis of gliomas is crucial. In this study, we sought to uncover the prognostic significance of immune cells and immune-related genes in the TME of gliomas. We incorporated data of 970 glioma patient samples from the Chinese Glioma Genome Atlas (CGGA) database as the training set, and an additional set of 666 samples from The Cancer Genome Atlas (TCGA) database served as the validation set. From our analysis, we identified 21 immune-related differentially expressed genes (DEGs) in the TME, which holds implications for glioma prognosis. Based on these genes, we constructed a prognostic risk model on the 21 genes. The prognostic risk model demonstrated robust performance with an area under the curve (AUC) value of 0.848. Notably, the risk score derived from the model emerged as an independent prognostic factor of gliomas, with high risk scores indicative of an unfavorable prognosis. Furthermore, we observed that high infiltration levels of certain immune cells, namely, activated dendritic cells, M0 macrophages, M2 macrophages, and regulatory T cells (Tregs), correlated with an unfavorable glioma prognosis. In conclusion, our findings suggested that the TME of gliomas harbored a distinct immune-associated signature, comprising 21 immune-related genes and specific immune cells. These elements significantly influence the prognosis and present potential as novel indicators in the clinical assessment of glioma patient outcomes

Associations of B Vitamin-Related Dietary Pattern during Pregnancy with Birth Outcomes: A Population-Based Study in Northwest China

This study aimed to derive a maternal dietary pattern to explain the variation in B vitamins during pregnancy and to investigate this pattern in relation to birth outcomes. A total of 7347 women who gave birth to live newborns less than one year were included. Their dietary pattern during pregnancy was derived using the reduced-rank regression method with six B vitamins as response variables. Associations between dietary pattern score and birth weight, gestational age at delivery, birth weight Z score, low birth weight, preterm, and small-for-gestational-age (SGA) were estimated using generalised linear mixed models. We identified a high B-vitamin dietary pattern characterised by high intakes of animal foods, vegetables, fungi and algae, legumes, and low intakes of oils and cereals. Women in the highest quartile of this pattern score had newborns with a 44.5 g (95% CI: 13.8, 75.2 g) higher birth weight, 0.101 (95% CI: 0.029, 0.172) higher birth weight Z score, and 27.2% (OR: 0.728; 95% CI: 0.582, 0.910) lower risk of SGA than those in the lowest quartile. Our study suggested that adherence to the high B-vitamin dietary pattern during pregnancy was associated with a higher birth weight and a lower risk of SGA