Beyond Yield Optimization: The Impact of Organosolv Process Parameters on Lignin Structure

When optimizing the process parameters of the acidic ethanolic organosolv process, the aim is usually to maximize the delignification and/or lignin purity. However, process parameters such as temperature, time, ethanol and catalyst concentration, respectively, can also be used to vary the structural properties of the obtained organosolv lignin, including the molecular weight and the ratio of aliphatic versus phenolic hydroxyl groups, among others. This review particularly focuses on these influencing factors and establishes a trend analysis between the variation of the process parameters and the effect on lignin structure. Especially when larger data sets are available, as for process temperature and time, correlations between the distribution of depolymerization and condensation reactions are found, which allow direct conclusions on the proportion of lignin's structural features, independent of the diversity of the biomass used. The newfound insights gained from this review can be used to tailor organosolv lignins isolated for a specific application

Lignin-Depolymerisation via UV-Photolysis and Titanium Dioxide Photocatalysis

Today, more than 70 million tons of lignin are produced by the pulp and paper industry every year. However, the utilization of lignin as a source for chemical synthesis is still limited due to the complex and heterogeneous lignin structure. The purpose of this study was a selective photodegradation of industrially available kraft lignin in order to obtain appropriate fragments and building block chemicals for further utilization, e.g. polymerization. Thus, kraft lignin obtained from soft wood black liquor by acidification was dissolved in sodium hydroxide and irradiated at a wavelength of 254 nm with and without the presence of titanium dioxide in various concentrations. Analyses of the irradiated products via SEC showed decreasing molar masses and decreasing polydispersity indices over time. At the end of the irradiation period the lignin was depolymerised to form fragments as small as the lignin monomers. TOC analyses showed minimal mineralisation due to the depolymerisation process

Approximation solution for steel concrete beam accounting high-order shear deformation using trigonometric-series

Steel concrete beams have a reasonable structure in terms of using material and high load carrying capacity. This paper deals with an approximate solution based on a trigonometric series for the static of steel concrete beams. The displacement field is based on the higher-order theory using Reddy’s hypothesis. The governing equations are derived from variation principles. An approximate solution based on the representation of displacement fields by trigonometric series is developed to solve the static problem of steel concrete beams. In order to verify the accuracy of the present approximate solution, numerical results are compared with those of exact solutions using classical beam theory. The displacements and nominal stress distributions in the depth direction are obtained with various high of beams. The present approximate approach can accurately predict the displacements and stresses of steel concrete beams

Approximation solution for steel concrete beam accounting high-order shear deformation using trigonometric-series

Steel concrete beams have a reasonable structure in terms of using material and high load carrying capacity. This paper deals with an approximate solution based on a trigonometric series for the static of steel concrete beams. The displacement field is based on the higher-order theory using Reddy’s hypothesis. The governing equations are derived from variation principles. An approximate solution based on the representation of displacement fields by trigonometric series is developed to solve the static problem of steel concrete beams. In order to verify the accuracy of the present approximate solution, numerical results are compared with those of exact solutions using classical beam theory. The displacements and nominal stress distributions in the depth direction are obtained with various high of beams. The present approximate approach can accurately predict the displacements and stresses of steel concrete beams

HỢP TÁC VIỆT - NGA TRONG CHẾ TẠO VÀ THỬ NGHIỆM MÁY THĂM DÒ ĐIỆN TỔ HỢP TEC-2 PHỤC VỤ KHẢO SÁT MÔI TRƯỜNG ĐỊA CHẤT TẦNG NÔNG

The geophysical investigation system named TEC-2 (Tomography Electric Complex-2) was designed, installed and tested in Institute of Marine Geology and Geophysics. This TEC-2 is the scientific cooperation product of Geomagnetic and Geoelectric Department of and POI and Geo - environmental Department of IMGG-VAST. The test results using TEC-2 show the capability of investigating by using certain pole system, short investigation time, high stability, the accuracy of two investigation times being more than 92%. The distributed design of electric poles, measuring operation, parameter selection, … are programmed and controlled automatically by computer. The TEC-2 system was used for investigating the weak structures in islands of Song Tu Tay, Son Ca, Nam Yet and Sinh Ton in Truong Sa Archipelagos and shallow geological environment in the area of Red River bank in Son Tay Hanoi. The acquired data  contributed to the success of the scientific projects managed by IMGG in the National Program of Bien Dong and islands in the period of 2011 - 2013 and VAST’s research project in the period of 2013 - 2014.Máy đo điện tổ hợp TEC-2 (Tomography Electric Complex-2)  được thiết kế, lắp ráp và thử nghiệm tại Viện Địa chất và Địa vật lý biển là sản phẩm hợp tác khoa học giữa phòng Địa từ điện của Viện Hàn lâm Khoa học Nga chi nhánh Viễn Đông (POI) và phòng Địa môi trường thuộc Viện Địa chất và Địa vật lý biển (IMGG). Kết quả đo thử nghiệm máy TEC-2 cho thấy khả năng đo tổ hợp nhiều phương pháp trên hệ điện cực bố trí sẵn, thời gian đo nhanh, độ ổn định của kết quả đo cao, độ chính xác giữa hai lần đo đạt trên 92%. Các thiết kế hệ điện cực, thao tác đo, chọn tham số được lập trình và điều khiển tự động bằng máy tính. Máy TEC-2 đã được sử dụng để nghiên cứu các đới cấu trúc yếu thuộc các đảo san hô Song Tử Tây, Cơn Ca, Nam Yết và Sinh Tồn thuộc quần đảo Trường Sa và môi trường địa chất tầng nông khu vực ven bờ Sông Hồng khu vực Sơn Tây Hà Nội. Các kết quả thu thập được đã đóng góp một phần quan trọng cho sự thành công của đề tài nghiên cứu do Viện Địa chất và Địa Vật lý biển chủ trì thuộc Chương trình Biển Đông và Hải đảo giai đoạn 2011 - 2013 và đề tài cấp Viện Hàn lâm Khoa học và Công nghệ Việt Nam giai đoạn 2013 - 2014

Assessment of impacts of utilization on water resources in the basin of trans-boundary Red river system

The Red river system is the large trans-boundary river system, there has been no united system of hydrology stations as well as integrated plan for the water use and management in the whole basin. The trend of water resources change in the Red river system basin has been assessed on the basic of statistic analyses of data observed during the studies, especially in the time when the exploitation of water resources has been intensified for the multisectoral development. This paper shows some of the results from considerations of the water use in the highlands that is influential in water resources in the Red river system basin and the planned reservoirs which are built in the basin of Red river system. The results include the assessment of the state and trend of water resources in the Red river system basin, the trend of water level lowering in the lowlands and its impacts

HORIZONTALLY PLASMON HYBRIDIZATION ON SYMMETRIC-BREAKING METAMATERIALS

In this report, we present a study on the fundamental negative-permeability metamaterials, named as the cut-wire-pair structure. The physics of the cut-wire-pair metamaterial is interpreted using the electromagnetic analog of molecular-orbital theory. It is shown that a symmetric-breaking cut-wire-pair metamaterial is horizontally plasmon-hybridized, leading to an additional magnetic resonance beyond the conventional one. The transmission spectra and the induced energy distributions are performed to demonstrate our prediction

Application of satellite images and VNREDSAT-1 images in study on marine environment in Truong Sa region

The remote sensing images, including images of MODIS, VNREDSAT-1 and altimeter, are applied for researching marine environment with the different resolutions. On the basis of different time remote sensing images, we concentrated on the assessment of several characteristics including the SST, chlorophyll-a concentration and sea surface current at the different depths in different monsoons as well. With the large areas, we used the images of MODIS and altimeter. The detailed research area focuses on the Nam Yet island, and the images of VNREDSAT-1 are used. The analysis method of environmental parameters of SST and chlorophyll-a used the regression functions based on the single and combined bands to enhance the accuracy of the analysis result. The marine parameters collected at different depths in the latest field surveys on Truong Sa archipelago in the years of 2015 and 2018 are presented in this paper. On the basis of these parameters, we can analyse the relationships and compare the real field survey data and corresponding results interpreted from remote sensing images

Study on spatial distribution of coral reefs in Nam Yet island by using GIS and remote sensing techniques

Research and application of GIS and remote sensing techniques combined with field survey in coastal areas of Nam Yet island had been carried out to establish the distribution map of submarine habitats. Depth-invariant index was used to correct water column’s effects on spectral reflectance of each habitat. The results of satellite image classification showed that area with well-developed coral at great depths accounted for 12%, area with well-developed coral at small depths accounted for 9%, area with poorly-developed coral accounted for 13%, dead coral area accounted for 15% and area of sand, grit, pebbles and weathered coral accounted for 51%. The assessment after classification showed that the overall accuracy of the satellite image interpretation process was 94% and the kappa coefficient was 0.93

Research on marine environment and coral distribution on Nam Yet island using VNRedsat-1 and QuickBird images

Based on the processing of VNRedsat-1 and QuickBird images in the area of Truong Sa archipelago, the research results showed the efficiency of assessing marine environmental characteristics in surroundings of these islands. In this paper, we presented the research results on Nam Yet island and adjacent area. The marine parameters in this research include sea surface temperature (SST) and chlorophyll-a concentration in the surface layer as well as in the deep layers of 20m and 40m, the distributions of the ground objects such as coral shelf, sand accumulation, coral reef combined with seagrass and seaweed. The accuracy of assessment of supervised and unsupervised classified results is approximate of 87.8%. The research results allowed assessing the environmental characteristics, warning of the risk of erosion and coastal line change in the study area