scholarly journals Preloading Effect On The Strength of Cement Mass Mixing Treated Salty Sand

Author(s):  
Rasoul Alipour

Abstract Existing problematic sub-layers in mixing technologies are a challenge, and for the first time, the effects of salt sub-layers in mass mixing technology have been investigated in this study for sandy salt in the southwest of Iran. This paper discusses the influence of adding various cement contents, Aw, and imposing different preloading values on the salty sand soil. First, salt and sand samples were dried, then, 90 % sand was mixed with 10% salt. After that, 30 % water was mixed thoroughly with the mixture of salty sand to obtain slurries. Cement slurry at a water-cement ratio (w/c) of 0.6 was then added to the sample and thoroughly mixed. The amount of cement in a slurry form that was added to the salty soil was 2, 4, 6, 8, and 10% by mass of dry soil. Each treated soil preloaded by 0, 9, and 45 kPa. After 120 days, the unconfined compressive strength of the sample was determined. Furthermore, by Scanning Electronic Microscope, SEM, the microstructures of treated samples were analyzed. At the end Unconfined Compression Strength, UCS, test results normalized to the non-preloaded treated soil. By increasing cement content, the effect of preloading in increasing UCS will decrease. In the SEM images for Aw=2%, the effect of preloading indicates porous shape for non-preloaded samples. Vice versa by Aw=8%, porous shape in the SEM images will disappear. In the end, treatability studies of pure salt in the thick layer have been investigated.

Acarologia ◽  
2021 ◽  
Vol 61 (3) ◽  
pp. 602-613
Author(s):  
Lucia Montes-Ortiz ◽  
Tom Goldschmidt ◽  
Lourdes Vásquez-Yeomans ◽  
Manuel Elías-Gutiérrez

A new planktonic species of the marine water mites of the family Pontarachnidae Koenike, 1910 is described from Corozal Bay, an estuarine system in Belize. The morphological description includes Scanning Electronic Microscope (SEM) images and is augmented by an analysis of DNA cytochrome c oxidase I (COI) sequences, the DNA barcode, used for the first time for a species description in this group.


2020 ◽  
Vol 2 (Supplement_3) ◽  
pp. ii22-ii22
Author(s):  
Yoshiki Arakawa ◽  
Junko Suga ◽  
Yukinori Terada ◽  
Kohei Nakajima ◽  
Masahiro Tanji ◽  
...  

Abstract Objective: Kyoto University Hospital has introduced the cancer genomic profiling tests, Oncoprime in 2015, Guardant360 in 2018, which are not under insurance coverage, FoundationOne CDx(F1CDx) and OncoGuide NCC Oncopanel system(NCC OP) in 2019, which received approval for insurance coverage for the first time in Japan. We investigated the results of cancer genomic profiling test under insurance coverage in our hospital. Methods: A special facility for the cancer genomic profiling tests was produced. To perform the cancer genomic profiling test, an outpatient must visit the facility three times (learning, ordering of the test, and getting the results). The expert panels decide the final test results and treatment options with the all information of the patients. Results: From November 2019 to March 2020, 51 and 9 patients were tested with F1CDx and NCC OP, respectively. 16 patients (31%) of F1CDX and 2 patients (22%) of NCC OP got treatment recommendations from the expert panels. However, only 5 patients (9.8%) of F1CDX and 1 patient (11%) of NCC OP received the treatments. The secondary finding suspecting germline mutations was found in 8 patients of F1CDX. Conclusion: After the approval the cancer genomic profiling tests with insurance coverage in Japan, it becomes easy for the patients to perform the test and get the genetic information of the tumor. However, it remains not easy to receive the recommended drugs because of several limitations of their usages.


2019 ◽  
Vol 946 ◽  
pp. 380-385
Author(s):  
Boris A. Chaplygin ◽  
Viacheslav V. Shirokov ◽  
Tat'yana A. Lisovskaya ◽  
Roman A. Lisovskiy

The strength of abrasive wheels is one of the key factors affecting the performance of abrasive machining. The paper discusses ways to improve the strength of abrasive wheels. The stress-state mathematical model presented herein is a generalization of the existing models. It is used herein to find for the first time that there are numerous optimal combinations of the elastic modulus and reinforcing material density, which result in the same minimum value of the objective function. It is found out that increasing the radius of the reinforcing component while also optimizing the mechanical properties of its material may increase the permissible breaking speed of the wheel several times. We herein present a regression equation and a nomogram for finding the optimal combination of control factors. Conventional methods for testing the mechanical properties of materials, which have been proven reliable for testing metals and alloys, are not as reliable for testing abrasive materials, as the test results they generate are not sufficiently stable or accurate. We therefore propose an alternative method that does not require any special equipment or special studies.


2011 ◽  
Vol 391-392 ◽  
pp. 1445-1449
Author(s):  
Chun Hua Zhang ◽  
Shi Lin Luan ◽  
Xiu Song Qian ◽  
Bao Hua Sun ◽  
Wen Sheng Zhang

The influences of low temperature on the interlaminar properties for PBO fiber/epoxy composites have been studied at liquid nitrogen temperature (77 K) in terms of three point bending test. Results showed that the interlaminar shear strength at 77 K were significantly higher than those at room temperature (RT). For the analysis of the test results, the tensile behaviors of epoxy resin at both room temperature and liquid nitrogen temperature were investigated. The interface between fiber and matrix was observed using SEM images.


1983 ◽  
Vol 73 (6A) ◽  
pp. 1895-1902
Author(s):  
Gerard C. Pardoen

Abstract The ambient vibration test results conducted on the Imperial County Services Building prior to the 15 October 1979 Imperial Valley earthquake are summarized. These results are of significant interest because the Imperial County Services Building has been the source of many postearthquake investigations due to the fact that the 1979 earthquake represented the first time a building instrumented with strong motion recorders suffered and recorded the major structural failure.


1975 ◽  
Vol 69 (8) ◽  
pp. 350-353
Author(s):  
John L. Morse

The most common question asked by the psychologist who is faced for the first time with assessing a visually handicapped child are answered. The 15 questions include such areas as the required information concerning visual condition, background of the client, test conditions, the role of the parents, classroom observation, behaviors observed during testing, evaluation of test results, expectations of parents and teachers, and modification of a child's inappropriate behaviors.


2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Duan-le Li ◽  
Da-peng Zheng ◽  
Dong-min Wang ◽  
Ji-hui Zhao ◽  
Cheng Du ◽  
...  

This paper investigated the effect of organic compounds with ester groups on the hydration and hardening of cement. The effects of five kinds of organic compounds with ester groups (ethyl acetate, dimethyl oxalate, glyceryl triacetate, trimethyl phosphate, and triethanolamine borate) on hydration heat, hydration degree, setting time, mechanical properties, microstructure, and pore structure of hardened cement slurry were studied. The test results showed that esters can make the end time of cement hydration induction longer and delay the occurrence of the second exothermic peak. Also, the effect of five kinds of esters on the hydration and hardening of cement was basically followed by TG> TB> DMO> EAC> TMP. In terms of molecular structure, for organic compounds containing only ester groups, the higher the number of ester groups, the greater the effect on the hydration of cement. The introduction of other functional groups (such as phosphate or borate) will influence the effect of the esters.


2016 ◽  
Vol 15 (3) ◽  
pp. 7-14 ◽  
Author(s):  
M. A. Koroleva ◽  
I. S. Koroleva ◽  
I. M. Zakroeva ◽  
I. M. Gruber

Relevance. One of the prognostic criteria meningococcal infection (MI) epidemic status process is the increasing number of resistant to antibiotics meningococcal strains. Aim of this study was to investigate the dynamics of invasive strains of N. meningitidis susceptibility to antibiotics in Moscow in 2006 - 2015. Materials and methods. Studied 98 strains of N. meningitidis, isolated from blood and cerebrospinal fluid of patients with MI. The study changes of sensitivity N. meningitidis to antibiotics was occured in two periods: first -2006 - 2011 and second - 2012 - 2015. The MIC was determined by E-test. Results. In the present study revealed for the first time the Russian strains of N. meningitidis, moderately resistant to penicillin (5 strains) and resistant to rifampicin (3 strains). Among the studied strains were not found resistant to ceftriaxone, ciprofloxacin, tetracycline and chloramphenicol. Discussion. Comparison results two study periods allowed to reveal the dynamics of increasing the sensitivity of N. meningitidis to antibiotics, which confirms the decline in meningococcal virulence, and as a result, continued interepidemic MI period. Conclusions. Despite the decline antibakterial resistance is required continuous monitoring.


Author(s):  
Natalia Lvovna Margolina ◽  
Irina Vladimirovna Nalimova

The article analyzes the concept of mathematical literacy. The formation of mathematical literacy among members of modern society is a fundamental basis for the formation of functional literacy. Currently, there is no single approach to the interpretation of the concept of "mathematical literacy", the article provides several different approaches to the definition. Based on the analysis of the points of view of different scientists, the authors of the article highlight the main components of the concept of "mathematical literacy". These include: literacy of mathematical speech; possession of mathematical concepts; the ability to correctly formulate definitions and statements; the ability to apply mathematics to research. The paper provides a characteristic of the listed components of mathematical literacy. In addition, in this work, for the first time, an attempt was made to formulate the levels of mathematical literacy – speech, terminological, critical and operational. The article presents the results of testing students in pedagogic areas of training of two universities – Kostroma State University and Yaroslavl State Pedagogic University. The test was aimed at assessing the level of mathematical literacy of future teachers, for whom teaching mathematics will be a part of their professional activities. The test tested not only the knowledge of terms and the ability to give definitions, but also the ability to correctly apply mathematics to solve practical problems with subsequent interpretation, as well as the ability to see errors and inaccuracies in the texts of students' works, Internet sources and teaching aids. The authors identified criteria for assessing the test results and for each criterion; a quantitative indicator was determined equal to the number of correctly completed tasks. The low results of even third-year students show topicality of specific activities that could help improve the mathematical literacy of pedagogues.


2018 ◽  
Vol 12 (2) ◽  
pp. 145-150 ◽  
Author(s):  
Ihor Dzioba ◽  
Sebastian Lipiec ◽  
Piotr Furmanczyk ◽  
Robert Pala

Abstract In the paper are presented test results of fracture process in brittle-to-ductile transition range for two microstructural types of S355JR steel – ferrite-pearlite and ferrite-carbides. For both kinds of S355JR steel obtained in temperature range of transition region the strength and plastic properties are similar, but the fracture toughness characteristics showed significantly are various. To clarify the differences in the course of trends in the mechanical characteristics performed metallographic and fractographic observations using the scanning electronic microscope. The fractographic examination showed that changes in the fracture surface morphology were dependent on the test temperature. It was also found that during the subcritical crack growth the region of ductile fracture extension reduced with decreasing temperature. The results of finite element method (FEM) calculation the stress fields in front of the crack of single edge notch in bending (SENB) specimens in the range of brittle-to-ductile transition are presented also. The FEM calculations were performed on the numerical model of SENB specimen using the ABAQUS program.


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