scholarly journals THE AMMONIA VAPORS INFLUENCE ON THE ELECTRICAL CHARACTERISTICS OF NANOSIZED TIN DIOXIDE FILMS OBTAINED USING A POLYMER

2021 ◽  
pp. 5-11
Author(s):  
A. Chebanenko ◽  
L. Filevska ◽  
V. Grinevych ◽  
V. Smyntyna ◽  
O. Negrutsa
Keyword(s):  
Tin Dioxide ◽  
Physical Adsorption ◽  
Main Role ◽  
Ammonia Vapor ◽  
Electrical Characteristics ◽  
Energy Bands ◽  
Adsorption And Desorption ◽  
Potential Barriers ◽  
Adsorbed Ammonia ◽  
Two Stages

In the presented paper the effect of ammonia vapors on the electrical properties of nanosized tin dioxide films obtained using polymers was investigated to assess the possibility of their use as an ammonia sensor’s sensitive element at room temperature. Ammonia vapor leads to a decrease in the conductivity of the studied SnO2 films. This is due to the fact that the adsorbed ammonia molecules increase the height of the intergranular potential barriers, and the surface shut-off bend of the energy bands. The main role in this is played by the processes of physical adsorption of ammonia molecules. The sensitivity of the films to ammonia vapor is in the range of 0.35-0.63 and reaches a maximum at a voltage of 300 V. The processes of adsorption and desorption take place in two stages and are reversible, as evidenced by the calculated time constants of adsorption and desorption.

Assessment of Laser Effects on the Structure and Electrical Properties of the Compound Bi2-xAgxSr2Ca2Cu3O10+δ Superconducting

2021 ◽  
Vol 19 (11) ◽  
pp. 108-115
Author(s):  
Nihad Ali Shafeek
Keyword(s):  
Critical Temperature ◽  
Hydraulic Press ◽  
Electrical Characteristics ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
X Ray ◽  
Compensation Ratio ◽  
Superconducting Compound ◽  
State Method ◽  
Two Stages

This research contains preparing the superconducting compound Bi2-xAgxSr2Ca2Cu3O10+δ and studying its structural and electrical characteristics. The samples were prepared using the solid-state method in two stages, and different concentrations of x were (x= 0.2,0.4,0.6,0.8) replaced instead of bismuth Bi. Then, using a hydraulic press 9 ton/cm2 and sintering with a temperature of 850°C, the samples were pressed. Next, x-ray diffraction is used to study the structural properties. The study of these samples was presented in different proportions of x values, where x = 0.4 is the best compensation ratio of x. A critical temperature of 1400C and the Tetragonal structure was got. After that, the effect of laser nidinium _ yak (Nd: YAG laser) was used on the compositional. It was found that the temperature value increased, so we got the best critical temperature, which is 142 0C.

Adsorption and Desorption of Cu / Zn Ions with Triethylenetetramine-Functionalized Adsorbents: Kinetics Study

2012 ◽  
Vol 209-211 ◽  
pp. 1999-2004
Author(s):  
Chang Kun Liu ◽  
Xu Xin Zhao ◽  
Hong Zhu ◽  
Xiao Fang Yue
Keyword(s):  
Adsorption Kinetics ◽  
Metal Ion ◽  
Single Species ◽  
Desorption Kinetics ◽  
Adsorption And Desorption ◽  
Diffusion Controlled ◽  
Initial Stage ◽  
And Performance ◽  
Two Stages ◽  
Zn Ions

Adsorption and desorption kinetics is critical in the efficiency and performance evaluation of the adsorbents. In this study, the adsorption and desorption kinetics of copper and/or zinc ions was investigated with the polyamine-functionalized adsorbents (P-TETA). The adsorption kinetics was studied in both single species system (when only one metal ion was present) and binary species system (when both metal ions were present). The adsorption kinetics in single species system was well fitted with two models at two stages for both Cu and Zn ions, indicating that the adsorption was diffusion-controlled at the initial stage and attachment-controlled at later stage. The adsorption kinetics in binary species system revealed the stronger coordination affinity of Cu ion with P-TETA than Zn ion. The desorption kinetics was well fitted with Elovich model for Cu ion desorption only, in both single and binary species system, with a higher desorption rate in single species system.

scholarly journals Low concentration volatile organic pollutants removal in combined adsorber-desorber-catalytic reactor system

2008 ◽  
Vol 62 (2) ◽  
pp. 51-58
Author(s):  
Zorana Arsenijevic ◽  
Gordan Savcic ◽  
Dragan Rankovic ◽  
Bosko Grbic ◽  
Nenad Radic ◽  
...  
Keyword(s):  
Energy Consumption ◽  
High Efficiency ◽  
Draft Tube ◽  
Physical Adsorption ◽  
Reactor System ◽  
Catalytic Reactor ◽  
Combined System ◽  
Adsorption And Desorption ◽  
Volatile Organic ◽  
Catalytic Incineration

The removal of volatile organic compounds (VOCs) from numerous emission sources is of crucial importance due to more rigorous demands on air quality. Different technologies can be used to treat the VOCs from effluent gases: absorption, physical adsorption, open flame combustion, thermal and catalytic incineration. Their appropriateness for the specific process depends on several factors such as efficiency, energy consumption, secondary pollution, capital investments etc. The distinctive features of the catalytic combustion are high efficiency and selectivity toward be?nign products, low energy consumption and absence of secondary polluti?on. The supported noble catalysts are widely used for catalytic incineration due to their low ignition temperatures and high thermal and chemical stability. In our combined system adsorption and desorption are applied in the spouted bed with draft tube (SBDT) unit. The annular zone, loaded with sorbent, was divided in adsorption and desorption section. Draft tube enabled sorbent recirculation between sections. Combustion of desorbed gases to CO2 and water vapor are realized in additive catalytic reactor. This integrated device provided low concentrations VOCs removal with reduced energy consumption. Experiments were conducted on a pilot unit of 220 m3/h nominal capacity. The sorbent was activated carbon, type K81/B - Trayal Corporation, Krusevac. A sphere shaped commercial Pt/Al2O3 catalyst with "egg-shell" macro-distribution was used for the investigation of xylene deep oxidation. Within this paper the investigations of removal of xylene vapors, a typical pollutant in production of liquid pesticides, in combined adsorber/desorber/catalytic reactor system is presented.

Dynamic Adsorption and Desorption of Toluene on Carbon Nanotubes Grafted Activated Carbon Fibers

2013 ◽  
Vol 284-287 ◽  
pp. 72-76 ◽  
Author(s):  
Yu Chun Chiang ◽  
Wei Hsiang Lin
Keyword(s):  
Carbon Nanotubes ◽  
Activated Carbon ◽  
Surface Area ◽  
Carbon Fibers ◽  
Physical Adsorption ◽  
Fixed Bed ◽  
Chemical Vapor Deposition Method ◽  
Active Surface Area ◽  
Activated Carbon Fibers ◽  
Adsorption And Desorption

Activated carbon fibers (ACFs) are widely used adsorbents due to their small fiber diameter, uniform pore size distribution and rapid adsorption/desorption rate. In addition, carbon nanotubes (CNTs) have received much attention recently because of their excellent mechanical and electrical properties and being candidates for adsorption. Thus, it should be highly interested as grafting CNTs onto ACFs to form a hybrid adsorbent. Therefore, the objective of this paper is to investigate the physicochemical properties of ACFs grafted with nitrogen-doped CNTs (CNs) and determine the adsorption and desorption performance of toluene vapor on this hybrid adsorbent. The chemical vapor deposition method was used for growth of CNs directly onto ACFs. The resulting materials were characterized by several techniques. Next, the adsorption breakthrough behaviors of toluene on the samples were measured in a continuous flow-type fixed-bed system. And then the temperature programmed desorption system was utilized to observe the desorption characteristics of toluene from the samples. Results show that the CNs have been grafted homogeneously onto the ACFs. The attachment of CNs on ACFs was believed to block part of the active surface area, causing the decrease in specific surface area and pore volume, but lead to the increase in microporosity. The adsorption of toluene on ACFs or the hybrid adsorbent was physical adsorption. At higher adsorption temperatures, the hybrid adsorbent could maintain high enough capacities of toluene and even exceed the performance of ACFs. Moreover, toluene could be desorbed completely from ACFs and the hybrid adsorbent up to 400 oC with the highest desorption efficiency at about 180 oC.

Quasi Drift and Quasi Diffusion: A Grain size Dependent Polysilicon Tft Model

1999 ◽  
Vol 557 ◽  
Author(s):  
W. Eccleston
Keyword(s):  
Grain Size ◽  
Crystalline Silicon ◽  
Electrical Characteristics ◽  
High Current ◽  
Field Effect Mobility ◽  
Physical Processes ◽  
Potential Barriers ◽  
Size Dependent ◽  
Physically Based ◽  
Polysilicon Tft

AbstractMost of the models for Thin Film Transistors take no account of the way that electrons move across grain boundaries. The purpose of this work is to produce an analytical model, physically based, that takes account of both the change in height of the potential barriers that separate the grains, and the change of carrier density in the grains with gate voltage. The high current and subthreshold regions are treated. The model enables the change of field effect mobility with grain size and temperature to be determined. Two closed form expressions are provided which should be of value to both device and circuit designers, as well as providing insight to the physical processes occurring in such devices. They form a close analogy with the electrical characteristics of MOSFETs on crystalline silicon, diffusion and drift being replaced by quasi-diffusion and primary quasi-drift.

scholarly journals The Influence of Si/Al Ratios on Adsorption and Desorption Characterizations of Pd/Beta Served as Cold-Start Catalysts

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1045 ◽  
Author(s):  
Ming Jiang ◽  
Jun Wang ◽  
Jianqiang Wang ◽  
Meiqing Shen
Keyword(s):  
Low Temperature ◽  
Active Sites ◽  
Catalytic Reduction ◽  
Physical Adsorption ◽  
Cold Start ◽  
Zeolite Catalysts ◽  
Adsorption And Desorption ◽  
Pd Dispersion ◽  
Ir Transmission ◽  
Lower Temperature

: The majority of NOx is exhausted during the cold-start period for the low temperature of vehicle emissions, which can be solved by using Pd/zeolite catalysts to trap NOx at low temperature and release NOx at a high temperature that must be higher than the operating temperature of selective catalytic reduction catalysts (SCR). In this work, several Pd/Beta catalysts were prepared to identify the influence of Si/Al ratios on NO and C3H6 adsorption and desorption characterizations. The physicochemical properties were identified using N2 physical adsorption, Fourier Transform Infrared Spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photo electron spectroscopy (XPS), and Na+ titration, while the adsorption and desorption characterizations were investigated by catalyst evaluation. The results indicated that the amount of dispersed Pd ions, the main active sites for NO and C3H6 adsorption, decreased with the increase of Si/Al ratios. Besides this, the intensity of Brønsted and Lewis acid decreased with the increase of Si/Al ratios, which also led to the decrease of NO and C3H6 adsorption amounts. Therefore, Pd dispersion and the acidic properties of Pd/Beta together determined the adsorption ability of NO and C3H6. Moreover, lower Si/Al ratios resulted in the formation of an additional dispersed Pd cationic species, Pd(OH)+, from which adsorbed NO released at a much lower temperature. Finally, an optimum Si/Al ratio of Pd/Beta was found at around 55 due to the balanced performance between the adsorption amounts and desorption temperature.

scholarly journals Adsorption and Desorption Properties of Total Flavonoids from Oil Palm (Elaeis guineensis Jacq.) Mature Leaf on Macroporous Adsorption Resins

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 778 ◽  
Author(s):  
Che Zain ◽  
Lee ◽  
Teo ◽  
Shaari
Keyword(s):  
Oil Palm ◽  
Adsorption Process ◽  
Elaeis Guineensis ◽  
Physical Adsorption ◽  
Radical Scavenging ◽  
Minimum Cost ◽  
Solution Ph ◽  
Adsorption And Desorption ◽  
Glass Column ◽  
Elaeis Guineensis Jacq

Three different macroporous resins (XAD7HP, DAX-8, and XAD4) were evaluated for their adsorption and desorption properties in preparing flavonoid-enriched oil palm (Elaeis guineensis Jacq.) leaf extract. The influences of initial concentration, solution pH, contact time, and desorption solvent (ethanol) concentration were determined by static sorption/desorption methods. The optimal condition for adsorption of flavonoids was achieved when the solution of the extract was adjusted to pH 7, reaching equilibrium after 1440 min at 298 K. The adsorption process was well described by a pseudo-second-order kinetics model, while the adsorption isotherm data fitted well with a Freundlich model. The adsorption by each resin was via an exothermic and physical adsorption process. Based on the static experiment results, XAD7HP was found to be the most appropriate adsorbent, while 80% ethanol was the best solvent for desorbent. Further evaluation of its dynamic adsorption and desorption characteristics on a packed glass column showed that XAD7HP could enrich the OPL total flavonoid content by a 3.57-fold increment. Moreover, UHPLC–UV/PDA and UHPLC–MS/MS analysis revealed that apigenin and luteolin derivatives were selectively adsorbed by XAD7HP. Additionally, both the crude OPL extract and the flavonoid-enriched fraction have good DPPH and NO free radical scavenging activities. Multiple interactions between the flavonoids and cross-linked polymeric XAD7HP resin through van der Waals forces and hydrogen bonding described the sorption processes. Therefore, by utilizing this method, the flavonoid-enriched fraction from crude OPL extract could be used as a potential bioactive ingredient in nutraceutical and pharmaceutical applications at minimum cost with optimum efficiency.

scholarly journals Молекулярные и клеточные механизмы воспаления при подагре

2019 ◽  
Author(s):  
I.Yu. Malyshev ◽  
A.E. Pihlak ◽  
O.P. Budanova
Keyword(s):  
Inflammatory Response ◽  
New Technologies ◽  
Therapeutic Potential ◽  
Main Role ◽  
Crystal Deposition ◽  
Inflammation Resolution ◽  
Two Stages ◽  
Nlrp3 Inflammasomes ◽  
Kinase Signaling Pathway

В обзоре проанализированы механизмы подагрического воспаления и разрешения острого воспаления при подагре, и то, как их понимание способствует созданию новых технологий лечения подагры. В первой части обзора анализируется кристалл-индуцированное воспаление при подагре, которое связано с активацией инфламмасомы NLRP3 в макрофагах, состоящее из двух этапов: 1) синтез компонентов инфламмасомы; и 2) сборка инфламмасомы. Проанализированы сигналы, активирующие синтез компонентов инфламмасомы, которые генерируются при взаимодействии кристаллов урата мононатрия с макрофагами. Описаны этапы инициации воспаления при подагре: синтез компонентов инфламмасомы, про-каспаз и про-IL-1β. IL-1β - основной эффекторный цитокин, который запускает не только воспалительный ответ, но и вызывает вазодилатацию сосудов, привлечение нейтрофилов к месту отложения кристаллов и еще большее усиление острого воспалительного эпизода через TLR-зависимую активацию NF-κB (фактор транскрипции). Рассматривается роль растворимой мочевой кислоты в активации инфламмасомы NLRP3. Подчёркнуто, что в разрешении острого воспаления при подагре основную роль играют те же клетки, что и в развитии классической воспалительной реакции: макрофаги и нейтрофилы. В обзоре рассмотрены сигнальные пути, которые переключают воспалительный ответ на разрешение и завершение воспаления: AMPK- (AMP-активируемая киназа) зависимый путь; антивоспалительные цитокины TGFβ1, IL-10 и IL-1Ra; белок аннексин А1 (AnxA1) и α1-антитрипсин (ААТ). Описаны способы терапевтического блокирования воспаления при подагре с помощью ингибиторов инфламмасомы и ингибиторов IL-1β. Изучение механизмов подагрического воспаления и его разрешения привело к идее о разработке методов репрограммирования иммунных клеток и адаптивной иммунотерапии подагры, методов, которые при других заболеваниях, таких как рак, уже показали выдающиеся возможности лечения больных.The review analyzes mechanisms of gouty inflammation and resolution of acute inflammation in gout and shows how their understanding contributes to creation of new technologies for the treatment of gout. The first part of the review addresses crystal-induced inflammation in gout, which is associated with activation of the NLRP3 inflammasome in macrophages. The crystal-induced inflammation consists of two stages, 1) synthesis of inflammasome components and 2) inflammasome assembly. The review analyzes signals activating the synthesis of inflammasome components, which are generated by the interaction of MSU (monosodium urate crystals) and macrophages. Stages of inflammation initiation are described, including the synthesis of inflammasome components, pro-caspases and pro-IL-1β. IL-1β is the main effector cytokine of gouty inflammation, which not only triggers the inflammatory response but also induces vasodilation, attraction of neutrophils to the place of crystal deposition, and even a greater potentiation of the acute inflammatory episode via the TLR-dependent activation of NF-κB (transcription factor). The role of soluble uric acid in the activation of NLRP3 inflammasomes is addressed. The main role in resolving acute gouty inflammation belongs to the same cells, macrophages and neutrophils, that contribute to the development of inflammation. The review focuses on signaling pathways switching the inflammatory response to inflammation resolution and termination, including the AMPK (AMP-activated kinase) signaling pathway, the TGFβ1, IL-10 and IL-1Ra anti-inflammatory cytokines, the protein annexin A1 (AnxA1), and α1-antitrypsin (AAT). The authors described in detail the techniques for therapeutic suppression of inflammation in gout using inflammasome and IL-1β inhibitors. Studying the mechanisms of gouty inflammation and its resolution has resulted in development of methods for reprogramming immune cells and adaptive immunotherapy of gout. These methods have already shown outstanding therapeutic potential for patients with other diseases such as cancer.

Sign in / Sign up

Export Citation Format

Share Document