scholarly journals Optimal conditions of acid modification of Bentonite-Like Clay

2021 ◽  
Vol 30 ◽  
pp. 02006
Author(s):  
Natalya Gorbunova ◽  
Aleksandr Vezentsev
Keyword(s):  
Mathematical Modeling ◽  
Sulfuric Acid ◽  
Calculation Method ◽  
Optimal Conditions ◽  
Optimal Parameters ◽  
Acid Modification ◽  
Modification Process

The results of mathematical modeling of the bentonite-like clay’s process of modifying various concentrations sulfuric acid depending on time the modification process is given in the presented article. As a result, the optimal parameters of this process were determined by the experimental and calculation method.

Mathematical Modeling of Betanin Extraction from Red Beet (Beta vulgaris L.) by Solid–Liquid Method

2015 ◽  
Vol 11 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Honggao Xu ◽  
Qiang Peng ◽  
Fang Yuan ◽  
Yanxiang Gao
Keyword(s):  
Mathematical Modeling ◽  
Effective Diffusion ◽  
Spherical Model ◽  
Extraction Process ◽  
Extraction Temperature ◽  
Optimal Parameters ◽  
Practical Application ◽  
Sulfurous Acid ◽  
Red Beet ◽  
Solid Liquid

Abstract Effective diffusion coefficient (D-value) is an important parameter for the extraction process. In this study, a cylindrical model to estimate the D-value of betanin extraction from red beet roots was developed. The influence of extraction temperature, pH, cylindrical thickness and type of acids on the D-value was also investigated. The optimal parameters of betanin extraction were 30°C, pH 4.0 adjusted with sulfurous acid or acetic acid. D-values under the above conditions were 18.95×10−11 m2/s and 17.87×10−11 m2/s, respectively. The result showed that D-value elevated with the increase of cylindrical thickness, which was consistent with earlier conclusion from spherical model. The modeling may be useful for the investigation into extraction process and practical application.

PROTOTYPE OF TRANSFEMORAL PROSTHESIS WITH AN ACTIVE ARTIFICIAL KNEE

2020 ◽  
Vol 4 (1) ◽  
pp. 172-180
Author(s):  
A.M. POLIAKOV ◽  
P.K. SOPIN ◽  
V.B. LAZAREV ◽  
A.I. RYZHKOV ◽  
M.A. KOLESOVA ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Control System ◽  
Knee Joint ◽  
Hierarchical Control ◽  
Control Level ◽  
Quality Criteria ◽  
Optimal Conditions ◽  
Invariant Moments ◽  
Biological Similarity ◽  
Transfemoral Prosthesis

This article presents a transfemoral prosthesis prototype with active control of an artificial knee joint. One of the main criteria used in the design of the prosthesis was to achieve the maximum biological similarity of this device in order to provide optimal conditions conducive to user natural walking. The artificial knee joint, designed on the basis of a polycentric higed mechanism with intersecting links, provides such conditions at the design level, and a three-level hierarchical control system, built on the basis of an intelligent-synergetic concept, at the control level. To recognize user's intentions, the intelligent subsystem uses algorithms for comparing graphic images of user's walking phases by the method of estimating the invariant moments of Hu. After that, prosthesis elements movements are planned in the synergistic subsystem in accordance with the synergistic quality criteria. The algorithms used in the control system are adjusted depending on what type of artificial foot is used in the prosthesis: active, semi-active or passive (purely mechanical). Mathematical modeling of the prosthesis operation shows that the nature of its functioning corresponds to the quality criteria adopted in the design.

scholarly journals The Role of m6A Ribonucleic Acid Modification in the Occurrence of Atherosclerosis

2021 ◽  
Vol 12 ◽  
Author(s):  
Jie Fu ◽  
Xinghui Cui ◽  
Xiaoyun Zhang ◽  
Min Cheng ◽  
Xiaoxia Li ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Biological Activities ◽  
Rna Modification ◽  
Acid Modification ◽  
Rna Methylation ◽  
Mrna Metabolism ◽  
Modification Process ◽  
M6a Rna Methylation ◽  
The Relationship

The N6-methyladenosine (m6A) modification is the most abundant epitranscriptomic modification in eukaryotic messenger RNA (mRNA). The m6A modification process is jointly regulated by various enzymes and proteins, such as methyltransferases, demethylases and related m6A-binding proteins. The process is dynamic and reversible, and it plays an essential role in mRNA metabolism and various biological activities. Recently, an increasing number of researchers have confirmed that the onset and development of many diseases are closely associated with the molecular biological mechanism of m6A RNA methylation. This study focuses on the relationship between m6A RNA modification and atherosclerosis (AS). It thoroughly summarizes the mechanisms and processes of m6A RNA modification in AS-related cells and the relationships between m6A RNA modification and AS risk factors, and it provides a reference for exploring new targets for the early diagnosis and treatment of AS.

Study and Fabrication of Acid-Modified Diatomite

2012 ◽  
Vol 512-515 ◽  
pp. 2175-2178
Author(s):  
Yan Jiang ◽  
Hua Ye ◽  
Li Na He
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Acid Treatment ◽  
Great Increase ◽  
Acid Modification ◽  
Catalyst Carrier ◽  
Modification Process ◽  
Large Mesopores ◽  
Potential Use ◽  
Modified Diatomite

This paper presents an investigation of the purification and activation of a raw diatomite by acid treatment. In the acid modification process, the SiO2 gel powder was adsorbed partially into the pure diatomite, blocking macropores and large mesopores of diatomite, which resulted in great increase of the specific surface area and SiO2 content of diatomite. Thus, the as-prepared diatomite has potential use in the fabrication of catalyst carrier.

A Calculation Method to Investigate the Effects of Geometric Parameters and Operational Conditions on the Static Characteristics of Aerostatic Spherical Bearings

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Hailong Cui ◽  
Huan Xia ◽  
Dajiang Lei ◽  
Xinjiang Zhang ◽  
Zhengyi Jiang
Keyword(s):  
Experimental Data ◽  
Calculation Method ◽  
Reynolds Equation ◽  
Geometric Parameters ◽  
Static Characteristics ◽  
Optimal Parameters ◽  
Film Pressure ◽  
Operational Conditions ◽  
Pressure Distributions ◽  
Calculation Results

In this paper, a calculation method based on matlab partial differential equations (PDE) tool is proposed to investigate the static characteristics of aerostatic spherical bearings. The Reynolds equation of aerostatic spherical bearings is transformed into a standard elliptic equation. The effects of geometric parameters and operational conditions on the film pressure, bearing film force, and stiffness are studied. The axial and radial eccentricities result in different film pressure distributions; the bearing film force and stiffness are significantly influenced by geometric parameters and operational conditions. The relative optimal parameters are confirmed based on the calculation results. A comparison between the numerical and experimental results is also presented. The highest relative error between the numerical results and the experimental data is 11.3%; the calculation results show good agreements with the experimental data, thus verifying the accuracy of the calculation method used in this paper.

scholarly journals Physicochemical and Mechanical Properties of Blow Spun Nanofibrous Prostheses Modified with Acrylic Acid and REDV Peptide

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1110
Author(s):  
Beata A. Butruk-Raszeja ◽  
Aleksandra Kuźmińska ◽  
Michał Wojasiński ◽  
Zuzanna Piotrowska
Keyword(s):  
Mechanical Properties ◽  
Fiber Diameter ◽  
Flow System ◽  
Average Pore Size ◽  
Internal Diameter ◽  
Optimal Parameters ◽  
Average Pore ◽  
Vascular Prostheses ◽  
Modification Process ◽  
Inner Surface

The paper presents a method of modifying the inner surface of nanofibrous vascular prostheses. The modification process involves two steps: introducing a hydrophilic linker, followed by a peptide containing the arginine-glutamic acid-aspartic acid-valine (REDV) sequence. The influence of the process parameters (reaction time, temperature, initiator concentration) on morphology and the distribution of fiber diameters were examined. For selected optimal parameters, the prostheses were modified in the flow system. Modifications along the entire length of the prosthesis were confirmed—the inlet and the outlet areas showed no significant (p > 0.05) differences in the value of the contact angle and the analyzed morphological parameters. The basic physicochemical and mechanical properties of modified prostheses were analyzed. The study showed that REDV-modified prosthesis has an average fiber diameter of 318 ± 99 nm, the average pore size of 3.0 ± 1.6 μm, the porosity of 48.4 ± 8.6% and Young’s modulus of 4.0 ± 0.4 MPa. The internal diameter of prostheses remains unchained and amounts to 3 mm. Such modified prostheses can reduce the risk of blood coagulation by increasing the surface’s wettability and, most of all, by introducing endothelial cell-selective peptide. As an effect, the proposed surfaces could recruit endothelial progenitor cells directly from the bloodstream and promote the endothelium formation after implantation.

Optimization of the Adsorption Condition for Wastewater Containing Chromium Treatment by Natural Adsorbent Material Using Response Surface Methodology

2014 ◽  
Vol 1033-1034 ◽  
pp. 387-390
Author(s):  
Ya Jun Wang ◽  
Jin Xi Wang ◽  
Yan Juan Li ◽  
Ying Wang
Keyword(s):  
Response Surface ◽  
Hexavalent Chromium ◽  
Removal Rate ◽  
Potassium Chromate ◽  
Optimal Experimental Design ◽  
Quadratic Model ◽  
Optimal Conditions ◽  
Optimal Parameters ◽  
Surface Method ◽  
Adsorption Condition

The effect of several important parameters on the removal of hexavalent chromium by humic acid was evaluated using an optimal experimental design based on Box-Behnken Response Surface method. The factors included temperature、pH、initial potassium chromate concentration and adsorbent dosage. A quadratic model for predicting the optimum removal conditions was derived, and the obtained optimal parameters were temperature 51°C, pH=2.34, initial potassium chromate concentration 14.30mg/L and adsorbent 0.58g. At the optimal conditions, the maximal removal rate of hexavalent chromium reached 73.17 %( forecast value was 73.26%).

Reduction-Roast Leaching of Low-Grade Pyrolusite Using Bagasse as a Reducing Agent

2013 ◽  
Vol 699 ◽  
pp. 28-33 ◽  
Author(s):  
Yun Fei Long ◽  
Jing Su ◽  
Xian Jia Ye ◽  
Hai Feng Su ◽  
Yan Xuan Wen
Keyword(s):  
Sulfuric Acid ◽  
Acid Concentration ◽  
Sulfuric Acid Concentration ◽  
Weight Ratio ◽  
Reducing Agent ◽  
Manganese Sulfate ◽  
Low Grade ◽  
Manganese Ore ◽  
Optimal Conditions ◽  
Roasting Temperature

Bagasse, a fibrous residue from sugarcane juice extraction, was used as a reducing agent to roast low-grade pyrolusite in N2. The roasted ore was further leached using sulfuric acid, to convert manganese oxide in the ore to manganese sulfate. The effects of weight ratio of bagasse to manganese ore, roasting temperature, roasting time, leaching temperature, leaching time, stirring speed and sulfuric acid concentration on the leaching recovery of manganese were investigated. Optimal conditions were determined to be a bagasse to manganese ore weight ratio of 0.8:10, roasting temperature of 500°C for 40 min, leaching stirring speed of 100 rpm, sulfuric acid concentration of 3 mol•L-1 and leaching temperature of 50°C for 40 min. The leaching recovery rate of manganese was up to 97.8% at the optimal conditions.

scholarly journals A COMPACTING PROCESS OF THE EN AW 6060 ALLOY

2015 ◽  
Vol 55 (5) ◽  
pp. 301 ◽  
Author(s):  
Lukáš Dragošek ◽  
Róbert Kociško ◽  
Andrea Kováčová ◽  
Robert Bidulsky ◽  
Milan Škrobian
Keyword(s):  
Density Distribution ◽  
Numerical Simulations ◽  
Vertical Channel ◽  
Processing Conditions ◽  
Optimal Conditions ◽  
Optimal Parameters ◽  
Under Five ◽  
Forward Extrusion ◽  
Deform 2D ◽  
Extrusion Method

<p>This study reports on an investigation of factors affect the process of compacting Al chips which are used to direct scrap processing through the forward extrusion method. EN AW 6060 chips of different geometry and types were mainly used as the experimental material. The chips were compacted in a die with a vertical channel (10.3mm in diameter). To provide a range of processing conditions, three different weights were selected and compacting was performed under five, different compacting pressures. The movement of the chips within the die during compacting was analysed through numerical simulations using Deform 2D software. Study of the compacting process optimal parameters for increasing the density and enhancing the density distribution were defined. The results from our study clearly show that optimal conditions are obtained when the proportion of D/h is 1/1.1. Moreover, it was recognized that in the process of small chips compacting, there was obtained lower density than in the case of large chips.</p>

Non-peripherally alkylamino-substituted phthalocyanines: Synthesis, spectral, photophysical and acid-base properties

2019 ◽  
Vol 23 (04n05) ◽  
pp. 427-436 ◽  
Author(s):  
Lucia Kociscakova ◽  
Merve Ipek Senipek ◽  
Petr Zimcik ◽  
Veronika Novakova
Keyword(s):  
Sulfuric Acid ◽  
Trifluoroacetic Acid ◽  
Fluorescence Emission ◽  
Optimal Conditions ◽  
Oxygen Production ◽  
Acid Base ◽  
Metal Free ◽  
Near Ir ◽  
Zinc Phthalocyanines ◽  
Photophysical Study

Non-peripherally substituted metal-free and zinc phthalocyanines (Pcs) bearing four diethylamino groups and four Br atoms were prepared. Optimal conditions for synthesis of corresponding precursor ([Formula: see text] 3-bromo-6-(diethylamino)phthalonitrile) either by nucleophilic substitution or by Buchwald–Hartwig coupling were studied. Noteworthy, 3,6-bis(diethylamino)phthalonitrile was also formed, nevertheless only at low yield (typically below 1%) and all attempts for its cyclotetramerization failed. Q bands of prepared Pcs were strongly red shifted up to the near-IR region (769 and 800 nm in THF for zinc and metal-free Pc, respectively). Unusually large hypsochromic shifts of the Q bands, 130 and 80 nm for metal-free and zinc Pc, respectively, were observed upon treating these Pcs with trifluoroacetic acid, which was attributed to the protonation of non-peripheral amines. Treatment with sulfuric acid led to subsequent protonation on the azomethine nitrogens as well. Photophysical study revealed low fluorescence emission of both derivatives ([Formula: see text] <0.03, in THF) and efficient singlet oxygen production only for zinc Pc ([Formula: see text] 0.77 in THF and 0.60 in DMF).

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