Synthesis and performance of water-retention PEMs with nafion-intercalating-montmorillonite hybrid

2008 ◽  
Vol 108 (1) ◽  
pp. 529-534 ◽  
Author(s):  
He Xiuchong ◽  
Tang Haolin ◽  
Pan Mu
Keyword(s):  
Water Retention ◽  
And Performance

State and Performance of Water Retention Structures of Earthen Irrigation Dams in Northern Ghana

2018 ◽  
Vol 1 (1) ◽  
pp. 34-43
Author(s):  
T. A. Adongo ◽  
F. K. Abagale ◽  
G. Kranjac-Berisavljevic
Keyword(s):  
Field Observation ◽  
Water Retention ◽  
Structural Defects ◽  
Northern Ghana ◽  
Key Informants ◽  
Storage Reservoirs ◽  
State Of Water ◽  
Northern Regions ◽  
And Performance ◽  
Retention Structures

The study assessed performance and state of water retention infrastructure of eight (8) irrigation schemes in three (3) northern regions of Ghana. Data was collected using field observation and key informants’ interviews. The results indicated that the Tono and Bontanga earthen irrigation dams’ embankments had no structural defects whereas the embankments of Libga, Golinga, Karni, Vea, Doba and Sankana had some structural defects. Except Libga, all the spillways had no structural deficiencies and signs of risk of failure. All the reservoirs contained some amounts of sediments and weeds. The night storage reservoirs at Tono and Vea were weedy and silted up. The developed irrigable areas of Vea, Tono, Doba, Sankana and Karni schemes had average irrigation rates ranging from 12 - 76 % for the years 2010 - 2017. The water retention infrastructure of the irrigation schemes are recommended for maintenance and periodic repairs to ensure sustainable water retention and availability for crop irrigation.

Preparation and Performance of Super-Absorbent Resin Using Polyacrylonitrile Fiber Wastes

2015 ◽  
Vol 1120-1121 ◽  
pp. 498-501
Author(s):  
Kun Yan Wang ◽  
Ru Feng Cen ◽  
Wen Wen Shu
Keyword(s):  
Water Retention ◽  
Polyacrylonitrile Fiber ◽  
Water Absorbency ◽  
Distilled Water ◽  
Weight Loss Step ◽  
Pan Fiber ◽  
New Material ◽  
Cross Linker ◽  
And Performance ◽  
Pan Fibers

In order to develop a new way for utilizing Polyacrylonitril (PAN) fiber wastes, a super-absorbent resin was prepared using the waste of PAN fibers at alkaline hydrolysis condition with Al3+ as cross-linker. The molecular structure of the super-absorbent resin was confirmed by FTIR. The thermal degradation of super-absorbent resin consisted of one main weight loss step. Factors that can influence absorbencies of the super-absorbent resin were investigated, such as the amount of cross-linker. The super-absorbent resin has the water absorbency of 131g/g in distilled water. The super-absorbent resin can be used as a new material to water retention from the soil in agriculture.

scholarly journals Construction of Porous Starch-Based Hydrogel via Regulating the Ratio of Amylopectin/Amylose for Enhanced Water-Retention

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3999
Author(s):  
Huiyuan Luo ◽  
Fuping Dong ◽  
Qian Wang ◽  
Yihang Li ◽  
Yuzhu Xiong
Keyword(s):  
Water Retention ◽  
Raw Materials ◽  
Retention Rate ◽  
Fixed Ratio ◽  
Chemical Properties ◽  
Retention Performance ◽  
And Performance ◽  
Traditional Natural ◽  
Water Retention Properties ◽  
Physical And Chemical

The performance of hydrogels prepared with traditional natural starch as raw materials is considerable; the fixed ratio of amylose/amylopectin significantly limits the improvement of hydrogel structure and performance. In this paper, starch hydrogels were prepared by physical blending and chemical grafting, with the aid of ultrasonic heating. The effects of different amylose/amylopectin ratios on the microstructure and water retention properties of starch hydrogels were studied. The results show that an increase in amylopectin content is beneficial to improve the grafting ratio of acrylamide (AM). The interaction between the AM grafted on amylopectin and amylose molecules through hydrogen bonding increases the pores of the gel network and thins the pore walls. When the amylopectin content was 70%, the water absorption (swelling 45.25 times) and water retention performance (16 days water retention rate 44.17%) were optimal. This study provides new insights into the preparation of starch-based hydrogels with excellent physical and chemical properties.

Transmission Scanning Electron Microscopy and Energy Analysis with the Siemens ELMISKOP 101

1972 ◽  
Vol 30 ◽  
pp. 450-451
Author(s):  
H. M. Thieringer
Keyword(s):  
Objective Lens ◽  
Transmission Microscopy ◽  
Image Recording ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Electron Microscopes ◽  
And Performance ◽  
Convergent Beam ◽  
Ray Path ◽  
Beam Diffraction

It has repeatedly been show that with conventional electron microscopes very fine electron probes can be produced, therefore allowing various micro-techniques such as micro recording, X-ray microanalysis and convergent beam diffraction. In this paper the function and performance of an SIEMENS ELMISKOP 101 used as a scanning transmission microscope (STEM) is described. This mode of operation has some advantages over the conventional transmission microscopy (CTEM) especially for the observation of thick specimen, in spite of somewhat longer image recording times.Fig.1 shows schematically the ray path and the additional electronics of an ELMISKOP 101 working as a STEM. With a point-cathode, and using condensor I and the objective lens as a demagnifying system, an electron probe with a half-width ob about 25 Å and a typical current of 5.10-11 amp at 100 kV can be obtained in the back focal plane of the objective lens.

Angular Resolved Electron Spectroscopy with Parallel Recording

1990 ◽  
Vol 48 (2) ◽  
pp. 370-371
Author(s):  
Huang Min ◽  
P.S. Flora ◽  
C.J. Harland ◽  
J.A. Venables
Keyword(s):  
Electron Spectroscopy ◽  
Low Voltage ◽  
Solid Angle ◽  
Detection System ◽  
Voltage Electron ◽  
Cylindrical Mirror ◽  
Inner Radius ◽  
Channel Plate ◽  
And Performance ◽  
Type Detector

A cylindrical mirror analyser (CMA) has been built with a parallel recording detection system. It is being used for angular resolved electron spectroscopy (ARES) within a SEM. The CMA has been optimised for imaging applications; the inner cylinder contains a magnetically focused and scanned, 30kV, SEM electron-optical column. The CMA has a large inner radius (50.8mm) and a large collection solid angle (Ω > 1sterad). An energy resolution (ΔE/E) of 1-2% has been achieved. The design and performance of the combination SEM/CMA instrument has been described previously and the CMA and detector system has been used for low voltage electron spectroscopy. Here we discuss the use of the CMA for ARES and present some preliminary results.The CMA has been designed for an axis-to-ring focus and uses an annular type detector. This detector consists of a channel-plate/YAG/mirror assembly which is optically coupled to either a photomultiplier for spectroscopy or a TV camera for parallel detection.

Novel epoxy/anhydride alternatives for biological electron microscopy: Physical and performance characteristis of embed 812 and LX 112 in combination with NSA/NMA/DMAE

1989 ◽  
Vol 47 ◽  
pp. 1000-1001
Author(s):  
Joe A. Mascorro ◽  
Gerald S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Succinic Anhydride ◽  
Volume Flow Rate ◽  
Mass Density ◽  
Uranyl Acetate ◽  
Volume Flow ◽  
Base Resin ◽  
And Performance ◽  
Acid Anhydrides

Embedding media based upon an epoxy resin of choice and the acid anhydrides dodecenyl succinic anhydride (DDSA), nadic methyl anhydride (NMA), and catalyzed by the tertiary amine 2,4,6-Tri(dimethylaminomethyl) phenol (DMP-30) are widely used in biological electron microscopy. These media possess a viscosity character that can impair tissue infiltration, particularly if original Epon 812 is utilized as the base resin. Other resins that are considerably less viscous than Epon 812 now are available as replacements. Likewise, nonenyl succinic anhydride (NSA) and dimethylaminoethanol (DMAE) are more fluid than their counterparts DDSA and DMP- 30 commonly used in earlier formulations. This work utilizes novel epoxy and anhydride combinations in order to produce embedding media with desirable flow rate and viscosity parameters that, in turn, would allow the medium to optimally infiltrate tissues. Specifically, embeding media based on EmBed 812 or LX 112 with NSA (in place of DDSA) and DMAE (replacing DMP-30), with NMA remaining constant, are formulated and offered as alternatives for routine biological work.Individual epoxy resins (Table I) or complete embedding media (Tables II-III) were tested for flow rate and viscosity. The novel media were further examined for their ability to infilftrate tissues, polymerize, sectioning and staining character, as well as strength and stability to the electron beam and column vacuum. For physical comparisons, a volume (9 ml) of either resin or media was aspirated into a capillary viscocimeter oriented vertically. The material was then allowed to flow out freely under the influence of gravity and the flow time necessary for the volume to exit was recored (Col B,C; Tables). In addition, the volume flow rate (ml flowing/second; Col D, Tables) was measured. Viscosity (n) could then be determined by using the Hagen-Poiseville relation for laminar flow, n = c.p/Q, where c = a geometric constant from an instrument calibration with water, p = mass density, and Q = volume flow rate. Mass weight and density of the materials were determined as well (Col F,G; Tables). Infiltration schedules utilized were short (1/2 hr 1:1, 3 hrs full resin), intermediate (1/2 hr 1:1, 6 hrs full resin) , or long (1/2 hr 1:1, 6 hrs full resin) in total time. Polymerization schedules ranging from 15 hrs (overnight) through 24, 36, or 48 hrs were tested. Sections demonstrating gold interference colors were collected on unsupported 200- 300 mesh grids and stained sequentially with uranyl acetate and lead citrate.

Trace nanoanalysis

1994 ◽  
Vol 52 ◽  
pp. 940-941
Author(s):  
D. E. Newbury ◽  
R. D. Leapman
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Detection Efficiency ◽  
Volume Element ◽  
And Performance ◽  
Trace Constituents ◽  
Secondary Ion ◽  
Concentration Levels ◽  
Structure Properties

Trace constituents, which can be very loosely defined as those present at concentration levels below 1 percent, often exert influence on structure, properties, and performance far greater than what might be estimated from their proportion alone. Defining the role of trace constituents in the microstructure, or indeed even determining their location, makes great demands on the available array of microanalytical tools. These demands become increasingly more challenging as the dimensions of the volume element to be probed become smaller. For example, a cubic volume element of silicon with an edge dimension of 1 micrometer contains approximately 5×1010 atoms. High performance secondary ion mass spectrometry (SIMS) can be used to measure trace constituents to levels of hundreds of parts per billion from such a volume element (e. g., detection of at least 100 atoms to give 10% reproducibility with an overall detection efficiency of 1%, considering ionization, transmission, and counting).

Relationship of stress and performance among first-year dental students

1986 ◽  
Vol 50 (5) ◽  
pp. 264-267 ◽  
Author(s):  
GH Westerman ◽  
TG Grandy ◽  
JV Lupo ◽  
RE Mitchell
Keyword(s):  
Dental Students ◽  
First Year ◽  
And Performance ◽  
Relationship Of
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