Component Condensation Research Articles

ENSURING WORK SAFETY DURING PREPARATION OF RAW GAS USING LOW TEMPERATURE SEPARATION UNIT

A host of complex gas, which is composed of an apparatus for implementing the process of low-temperature separation, is characterized by high pressures. So, gas coming from gas fields may reach values of pressure 12 MPa, which in the event of an accident, creates a risk of harm to the staff servicing this node. Thus, the necessary calculation of wall thickness of pipelines and gas equipment. Besides, the condensation of the heavy components of the gas stream is accompanied by a significant release of cold, which can cause adverse effects on personnel working with this equipment. Supersonic separation involves the expansion of pre-cleaned from mechanical impurities downhole products in a supersonic nozzle profile, which is accompanied by temperature decrease. When passing the critical section of the nozzle the gas flow reaches the speed of sound and later in the diffuser is cooled to the desired temperature. From the point of view of ensuring safety of the working personnel, the implementation method of low-temperature separation allows to avoid unwanted negative effects. This is because this technology does not involve the participation of employees, during the implementation of technological operations, as required, for example, the expander technology. The paper discusses promising from the point of view of modernization of existing installations of complex preparation of gas of low-temperature separation of a supersonic technology based on the use of isentropic expansion, followed by isentropic compression of the gas stream instead of the classic isoenthalpic cooling. For analysis of the nozzle was realized a mathematical model of the supersonic nozzle. Numerical simulation plays an important role in accelerating the development of the method necessary to optimize and improve the separation efficiency and reduce the cost of this method. To ensure trouble-free operation of the technology in question was used to calculate the thickness of the wall based on the loads acting on the profile, caused by the pressure of the medium inside the nozzle, and stresses in the metal from temperature changes.

Synthesis of dihydropyridines and quinoxaline drivatives using 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium chloride as a new, reusable and efficient Bronsted acidic ionic liquid catalyst

In this work, the efficiency, generality and applicability of new silica supported Bronsted acidic ionic liquid (BAIL) 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium chloride as heterogeneous and green catalyst for organic transformations are studied. Herein, the following one-pot multi-component reactions in the presence of [Msei]Cl are investigated: (i) the synthesis of quinoxaline derivatives from phenylendiamine and 1,2-diketones in EtOH and under mild conditions (room temperature), (ii) the preparation of 1,4-dihydropyridines from one-pot multi component condensation of 1,3-dicarbonyl compounds(2 equiv.), NH4OAc (1.5 equiv.) and aldehydes (1 equiv.) under solvent-free conditions at moderate temperature (90 °C). High yields, relatively short reaction times, efficiency, generality, clean process, simple methodology, low cost, easy work-up, ease of preparation and regeneration of the catalyst and green conditions (in the synthesis of the quinoxaline derivatives) are advantages of the application of [Mesi]Cl as catalyst in the above organic reactions.

One-pot three-component synthesis of 2-Amino-4H-Chromene derivatives by using monodisperse Pd nanomaterials anchored graphene oxide as highly efficient and recyclable catalyst

An efficient and environmentally benign method has been developed for the synthesis of 2-amino-4H-chromene derivatives via one-pot multi component condensation of resorcinol (1), malononitrile (2), and various aromatic aldehydes (3a–j), using highly monodisperse palladium nanoparticles supported with graphene oxide (Pd@GO) as a heterogeneous catalyst. An advantageous of this method is that monodisperse Pd@GO nanoparticles can be easily separated and reused several times for further runs. This highly stable and monodisperse catalyst has been used for the first time as highly efficient, long lived and isolable catalyst for the synthesis of 2-amino-4H-chromene derivatives from resorcinol, aromatic aldehydes and malononitrile with great catalytic performance and easy work-up procedure. The structure and morphology of synthesized catalyst were characterized by using different techniques such as, transmission electron microscopy (TEM), the high resolution electron micrograph (HRTEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The highly crystalline, colloidally stable and highly monodisperse Pd@GO formation were shown by using these techniques. Besides, the Pd@GO has been found to be highly efficient and recyclable heterogeneous catalyst for the synthesis of 2-amino-4H-chromene derivatives.

Solitons and modulation instability for the three-component Gross-Pitaevskii equations in the spinor Bose-Einstein condensate

Under investigation in this paper are the three-component Gross-Pitaevskii equations in the spinor Bose-Einstein condensate. We derive the one- and two-soliton solutions for the one, two and three components of the spinor Bose-Einstein condensate. We also discuss the collisions between the two solitons for one and two components of the spinor Bose-Einstein condensate, and find that the collisions are elastic. We make the linear-stability analysis of the solitons for the one and two components of the spinor Bose-Einstein condensate and obtain the conditions for the modulational instability of the solitons, respectively. Based on the one-soliton solutions for the three components of the spinor Bose-Einstein condensate, we see that the period of the one soliton depends on the frequency in space coordinates x axis, ωx, Planck constant, ℏ, and s-wave scattering lengths of the total spin f=2, a2. The smaller ωx and ℏ, the longer the period; the larger a2, the longer the period.

Synthesis of Aminofuran-Linked Benzimidazoles and Cyanopyrrole-Fused Benzimidazoles by Condition-Based Skeletal Divergence

A condition-based skeletal divergent synthesis was explored to achieve skeletal diversity in two component condensation reaction. Cyanomethyl benzimidazole was reacted with α-bromoketone under thermal conditions to furnish 2-aminofuranyl-benzimidazoles, while the same reaction afforded 3-cyano-benzopyrrolo-imidazoles under microwave irradiation. Two nonequivalent nucleophilic centers on benzimidazole moiety were manipulated elegantly by different reaction conditions to achieve the skeletal diversity.

Modification, Characterization, and Catalytic Application of Mesolite for One Pot Synthesis of 3-Methyl-4-arylmethylene-isoxazol-5(4H)-ones

Natural mesolite type zeolite was collected, modified by sulphuric acid treatment and characterized by using Powder-X ray diffraction, Scanning electron microscopy and Energy dispersive spectroscopy, Fourier transform infrared spectroscopy. Temperature programmed ammonia desorption, Brunauer-Emmer-Teller surface area analysis. Modified dealuminated mesolite shows an efficient catalytic activity for one pot synthesis of 3-methyl-4-arylmethylene-isoxazol-5(4H)-ones derivatives, via one pot three component condensation of benzaldehyde, ethylacetoacetate and hydroxylamine hydrochloride. Present method offers several advantages over the reported methods like a simple and inexpensive modification of catalyst, mild reaction condition, easy separation of catalyst, simple work-up procedure, nonchromatographic isolation and purification desired product and excellent yield. Furthermore, catalyst could be reused without significant loose in activity.

Theoretical and experimental analysis evaluating the optimal generation temperature of NH3-H2O absorption refrigeration machine for ice-making


 
 
 Absorption refrigeration cycle used a common mixture of NH3-H2O has been developing widely. However, almost previous studies are system theory studies and exclusive applications or experimental studies for each component of the system. This paper is (shown?) showed the state points of the fluids in designed NH3-H2O absorption refrigeration machine that is the corporation of theoritical (theoretical?) calculations and practical measurements of a completed machine and steady working. The purpose of this paper is optimizing the working condition for (the?) entire machine according to the condition in Vietnam and satisfying the heat supplying (supply?). The correlation of optimal generation temperature with condensation, absorption and evaporation temperatures of the machine components are set into (a?) an regression equation which was established in the multivariate regression method. The optimal coefficients of performance were compared with experiments having the average deviation is 1.2% and with other studies having the deviations are from 2 to 7%. 
 
 

Magnetite Nanoparticles-Supported APTES as a Powerful and Recoverable Nanocatalyst for the Preparation of 2-Amino-5,10-dihydro- 5,10-dioxo-4H-benzo[g]chromenes and Tetrahydrobenzo[g]quinoline-5,10- diones.

This study introduces a green and effective approach for the preparation of biologically-active heterocyclic compounds including 2-amino-5,10-dihydro-5,10-dioxo-4Hbenzo[ g]chromenes and tetrahydrobenzo[g]quinoline-5,10-diones using one-pot multi-component reactions in the presence of Fe3O4@SiO2-NH2 nanocomposite. The preparation and use of aminofunctionalized Fe3O4@SiO2 as a powerful and reusable nanocatalyst is described. The catalyst was characterized by spectral techniques including FT-IR, SEM, XRD, EDX and VSM analysis. This method offers the advantages of high yields, short reaction times, comfortable work-up and reusability of the catalyst. The amino-functionalization silica-coated magnetite nanocomposite was prepared by three step method and the structure elucidation of the nanocatalyst has been done using various spectroscopic analyses. Then, the Fe3O4@SiO2-NH2 nanocomposite was used in the multicomponent synthesis of 2-amino-5,10-dihydro-5,10-dioxo-4H-benzo[g]chromenes and tetrahydrobenzo[g]quinoline-5,10-diones under reflux conditions. All of the products were analyzed with m.p., 1H NMR, 13C NMR and FT-IR spectroscopy techniques. The study on the recoverability of the nanocatalyst showed the recovered Fe3O4@SiO2-NH2 nanocomposite could be reused sixth consecutive times with a little-decreased activity. Amino-functionalized SiO2 coated Fe3O4 nanocomposite exhibited superparamagnetic behavior and strong magnetization at room temperature. The average crystallite sizes of the catalyst was about 50-60 nm. The obtained magnetic nanocomposite showed excellent catalytic activity as a new heterogeneous magnetic catalyst for the synthesis of some benzo[g]chromenes and tetrahydrobenzo[g]quinoline-5,10-diones. We propose that NH2 groups on the surfaces of nanocomposite act as the Brønsted base and cause to dehydrogenation of substrates to promote the reactions. It was found that Fe3O4@SiO2-NH2 nanocomposite act as an eco-friendly and efficient catalyst for one-pot synthesis of three/four component condensation reactions. In this research, aminofunctionalized Fe3O4@SiO2 was used as recoverable catalyst for the synthesis of 2-amino-5,10- dihydro-5,10-dioxo-4H-benzo[g]chromenes and tetrahydrobenzo[g]quinoline-5,10-diones under reflux conditions. The significant advantages of this method are the reasonably simple work-up, little catalyst loading, short reaction times, excellent yields, non-hygroscopic quality and reusability of the nanocatalyst which is in good agreement with green chemistry disciplines.

Integrating sustainable biofuel and silver nanomaterial production for in situ upgrading of cellulosic biomass pyrolysis

Replacing fossil fuels with biomass-based alternatives is a potential carbon neutral, renewable and sustainable option for meeting the world’s growing energy demand. However, pyrolytic conversions of biomass-to-biofuels suffer marginal total energy gain, and technical limitations such as bio-oils’ high viscosity and oxygen contents that result in unstable, corrosive and low-value fuels. This work demonstrates a new integrated biorefinery process for the co-production of biofuels and silver nanomaterials. By impregnating pure cellulose and corn stalk with silver nitrate, followed by pyrolysis, the gas yield (especially hydrogen) increases substantially. The condensable bio-oil components of the impregnated samples are considerably higher in furfurals (including 5-hydroxymethylfurfural). Though the overall activation energy barrier, as determined via the Distributed Activation Energy Model, does not change significantly with the silver nitrate pre-treatment, the increase in gases devolatilized, and improved 5-hydroxymethylfurfural yield, suggest a catalytic effect, potentially increasing decarboxylation reactions. After using this metal impregnation to improve pyrolysis fuel yield, following pyrolysis, the silver-char composite materials are calcined to remove the biomass template to yield silver nanomaterials. While others have demonstrated the ability to biotemplate such nanosilver on cellulosic biomass, they consider only impregnation and oxidation of the template. This is the first work that demonstrates the potential to extract upgraded biorenewable fuels during the biotemplating of nanomaterials, the same nanomaterials often used in catalytic energy applications.

Synthesis, molecular docking, antimycobacterial and antimicrobial evaluation of new pyrrolo[3,2-c]pyridine Mannich bases

In this report, we describe the synthesis and biological evaluation of a new series of pyrrolo[3,2-c]pyridine Mannich bases (7a-v). The Mannich bases were obtained in good yields by one-pot three component condensation of pyrrolo[3,2-c]pyridine scaffold (6a-c) with secondary amines and excess of formaldehyde solution in AcOH. The chemical structures of the compounds were characterized by 1H NMR, 13C NMR, LC/MS and elemental analysis. Single crystal X-ray diffraction has been recorded for compound 7k ([C23H29ClN4]+2, H2O). The in vitro antimicrobial activities of the compounds were evaluated against various bacterial and fungal strains using Agar diffusion method and Broth micro dilution method. Compounds 7e, 7f, 7r, 7t, and 7u were showed good Gram-positive antibacterial activity against S. aureus, B. flexus, C. sporogenes and S. mutans. Furthermore, in vitro antimycobacterial activity was evaluated against Mycobacterium tuberculosis H37Rv (ATCC 27294) using MABA. Compounds 7r, 7t, and 7u were showed good antitubercular activity against Mtb (MIC ≥6.25 μg/mL). Among the tested compounds, 1-((4-chloro-2-(cyclohexylmethyl)-1H-pyrrolo[3,2-c]pyridin-3-yl)methyl)piperidine-3-carboxamide (7t) was showed excellent antimycobacterial activity against Mtb (MIC <0.78 μg/mL) and low cytotoxicity against the HEK-293T cell line (SI >>25). Molecular docking of the active compounds against glutamate racemase (MurI) and Mtb glutamine synthetase were explained the structure-activity observed in vitro.

Weakly Anisotropic Noncentrosymmetric Superconductors with Radial Line Nodes and the Origin of the Anomalous Thermodynamic Data

In noncentrosymmetric superconductors (NCSs), the inversion symmetry (IS) is most commonly broken by an antisymmetric spin-orbit coupling (SOC) removing the spin degeneracy and splitting the Fermi surface (FS) into two branches. A two component condensate is then produced with a doublet pair potential mixing an even singlet and an odd triplet. When the triplet and the singlet strengths are comparable, the pair potential can have rich nodes. The angular line nodes (ALNs) are associated with strong anisotropy and they are widely studied in the literature. When the anisotropy is not strong, they can be replaced by other types of nodes in closed or open forms affecting the low temperature properties. Here, we focus on the weakly anisotropic case and the line nodes in the superconducting plane which become circular in the limit of full isotropy. We study the topology of these radial line nodes (RLNs) and show that it is characterized by the $Z_2$ classification similar to the Quantum-Spin-Hall Insulators. From the thermodynamical perspective, the RLNs cause, even in the topological phases, an exponentially suppressed low temperature behaviour which can be mistaken by nodeless s-wave pairing, thus, providing an explanation to a number of recent experiments with contraversial pairing symmetries. In the rare case when the RLN is on the Fermi surface, the exponential suppression is replaced by a linear temperature dependence. The RLNs are difficult to detect, and for this reason, they may have escaped experimental attention. We demonstrate that Andreev conductance measurements with clean interfaces can efficiently probe the weakly anisotropic samples where the RLNs are expected to be found.

Rankinite synthesis and pyrolysis inversion

The thermal transformation of the pyrolysis–condensation–rankinite synthesis process at a normal pressure is considered in detail. Rankinite pyrolysis is performed with a step-by-step increase in enthalpy (TERRA software system). Rankinite pyrolysis components condense on a surface with temperature Т = 298.15 K. Condensate components are equivalent to pyrolysis components. Wollastonite and limestone can precipitate upon condensation to form a mineral deposit. Synthesis is performed by mixing the condensate components. The components and heat of chemical reactions, the enthalpy, the temperature, and the heat content are determined. It is shown that the decomposition of rankinite (Т dec = 2598.36 K), wollastonite (Т dec = 3662.7 K), and limestone (Т dec = 3680–3810 K) occurs in the process of synthesis and pyrolysis at a constant temperature. The complete pyrolysis–condensation–synthesis process picture typical for various compounds is given.

Influence of combined pretreatments on color parameters during convective drying of Mirabelle plum (Prunus domestica subsp. syriaca)

Discoloration and browning are caused primarily by various reactions, including Maillard condensation of hexoses and amino components, phenol polymerization and pigment destruction. Convective drying can be combined with various pretreatments to help reduce undesired color changes and improve color parameters of dried products. In this study, effects of ultrasound-assisted osmotic dehydration as a pretreatment before convective drying on color parameters of Mirabelle plum were investigated. Variations of L* (lightness), a* (redness/greenness), b* (yellowness/blueness), total color change (ΔE), chroma, hue angle and browning index values were presented versus drying time during convective drying of control and pretreated Mirabelle plums as influenced by ultrasonication time, osmotic solution concentration and immersion time in osmotic solution. Samples pretreated with ultrasound for 30 min and osmotic solution concentration of 70% had a more desirable color among all other pretreated samples, with the closest L*, a* and b* values to the fresh one, showing that ultrasound and osmotic dehydration are beneficial to the color of final products after drying.

Inverted solitons in a spin-orbit-coupled Bose-Einstein condensate

We investigate the “inverted” solitons in spin-orbit-coupled Bose-Einstein condensate with one-dimensional spatially periodic Zeeman field. Soliton existence depends on the exact invert for the condensate components in the spatially periodic Zeeman field. And the position and the total pseudomagnetization density of the solitons can be controlled by the spatially periodic Zeeman field. Simulated results show that the inverted solitons can be stable for the interatomic attractive interactions.

Nanofibrous matrixes with biologically active hydroxybenzophenazine pyrazolone compound for cancer theranostics

The nanomaterial with the novel biologically active compounds has been actively investigated for application in cancer research. Substantial use of nanofibrous scaffold for cancer research with potentially bioactive compounds through electrospinning has not been fully explored. Here, we describe the series of fabrication of nanofibrous scaffold loaded with novel potential biologically active hydroxybenzo[a]phenazine pyrazol-5(4H)-one derivatives were designed, synthesized by a simple one-pot, two step four component condensation based on Michael type addition reaction of lawsone, benzene-1,2-diamine, aromatic aldehydes and 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one as the substrates. The heterogeneous solid state catalyst (Fe (III) Y-Zeolite) could effectively catalyze the reaction to obtain the product with high yield and short reaction time. The synthesized compounds (5a–5p) were analyzed by NMR, FTIR and HRMS analysis. Compound 5c was confirmed by single crystal XRD studies. All the compounds were biologically evaluated for their potential inhibitory effect on anticancer (MCF-7, Hep-2) and microbial (MRSA, MTCC 201 and FRCA) activities. Among the compounds 5i exhibited the highest levels of inhibitory activity against both MCF-7, Hep-2 cell lines. Furthermore, the compound 5i (BPP) was evaluated for DNA fragmentation, flow cytometry studies and cytotoxicity against MCF-7, Hep-2 and NIH 3T3 fibroblast cell lines. In addition, molecular docking (PDB ID: 1T46) studies were performed to predict the binding affinity of ligand with receptor. Moreover, the synthesized BPP compound was loaded in to the PHB-PCL nanofibrous scaffold to check the cytotoxicity against the MCF-7, Hep-2 and NIH 3T3 fibroblast cell lines. The in vitro apoptotic potential of the PHB-PCL-BPP nanofibrous scaffold was assessed against MCF-7, Hep-2 cancerous cells and fibroblast cells at 12, 24 and 48h respectively. The nanofibrous scaffold with BPP can induce apoptosis and also suppress the proliferation of cancerous cells. We anticipate that our results can provide better potential research in nanomaterial based cancer research.

Clean synthesis of novel spiro[indene-2,2’-[1,3,5]-oxathiazine]-1,3-diones in water

In this work, we have designed an efficient and convenient method for the synthesis of novel spiro[indene-2,2'-[1,3,5]oxathiazine]-1,3-diones by the one-pot, three component condensation of tetramethyl guanidine, ninhydrin, and isothiocyanates in water. Easy purification, green reaction conditions, easy performance and good yields are some advantages of this procedure.

Desorption of Mercaptans and Water from a Silica–Alumina Gel

An industrially widely used technology for the removal of condensable components like water and mercaptans from natural gas is cyclic temperature swing adsorption. Optimized design of these coupled adsorption–desorption processes requires detailed knowledge of desorption properties of the used adsorbents. Therefore, the desorption behavior of water, methyl mercaptan, and ethyl mercaptan was investigated on a commercial silica–alumina gel. In dynamic experiments, a preloaded fixed bed was regenerated with hot purge gas (300 °C), and time-dependent concentration and temperature profiles were measured and discussed by means of equilibrium theory. Characteristic plateau temperatures were found between 43 and 63 °C, rising with the adsorption affinity. Experiments with competitive adsorption of water and mercaptans show that process dynamics are mainly controlled by water. The results are evaluated with regard to technical relevance.

Contribution to the Modeling of a Solar Adsorption Refrigerator under the Climatic Conditions of Burkina Faso

This work concerns a dynamic modeling and a numerical simulation of the operation of an adsorption solar refrigeration system using the zeolite-water couple. For this, a mathematical model representing the evolution of heat and mass transfer at each component of the solar adsorption refrigerator has been developed. We have adopted the Dubinin-Astakhov model for the adsorption kinetics of the zeolite/water pair. This model allows to describe the phenomenon of adsorption and to calculate the rate of adsorbate (water) in the zeolite (adsorbent) as a function of the temperature and the pressure. The equations governing the operation of the solar adsorption refrigerator, deduced from the thermal and mass balances established at the collector adsorber, condenser and evaporator components, were solved by an implicit finite difference scheme and Gauss Seidel’s iterative method. We have validated the model established by applying it to the model of Allouhi et al. 2014. We analyzed the influence of the adsorbate/adsorbent couples, the solar flux, the ambient temperature on the adsorption and desorption process. The temperature profiles obtained representing the temperature evolution of the glass, the absorbent plate, the zeolite-water mixture, the condenser, the evaporator, as well as the pressure and the adsorbed mass allowed us to evaluate the performance of the solar adsorption refrigerator. SCOP is higher the higher the solar flux captured by the collector-adsorber.

MgO/ZrO2 Promoted with SrO and CsO as a Reusable Nano Catalysts for One Pot Synthesis of 2-Amino-2-Chromene

MgO-ZrO2 powder (MZ30) containing 30 wt% MgO was prepared by simple precipitation method. Two other catalysts were obtained by loading MZ30 powder with 5 wt% SrO and CsO using incipient wetness impregnation method. The catalytic performance of these catalysts was evaluated for synthesis of 2-amino-2-chromene via one pot three components condensation of benzaldhyde with malononitrile and α-naphthol. Different techniques such as N2 physisorption, TGA-DTA, XRD, TEM, Hammet indicator method and CO2-TPD have been used to characterize the investigated catalysts. Reaction paameters such as reaction temperature, synthesis time and catalyst amount were studied to optimize the reaction conditions. The observed activity of these catalysts were correlated to their basicity and other surface parameters. Synthesis of 2-amino-2-chromene may involve moderate and strong basic sites of PKBH+ in the range ≥ 9.8 and ≤ 15.0. Base sites of PKBH+ are too weak to contribute in the synthesis processes.

离子液体1-丁基-3-羧甲基苯并三唑三氟乙酸盐催化三组分缩合反应合成氨基萘酚化合物

本文报道了一种离子液体1-丁基-3-羧甲基苯并三唑三氟乙酸盐催化β-萘酚、芳香醛和胺在无溶剂条件下发生三组分缩合反应绿色、高效合成氨基萘酚化合物的方法。离子液体催化剂至少可以循环使用5次，并且活性没有明显降低。 A green and highly efficient approach for the synthesis of aminonaphthols via ionic liquid 1-butyl-3-carboxymethyl benzotriazole trifluoroacetate catalyzed three component condensation recation of β-naphthols, aromatic aldehydes and amines under solvent-free conditions has been reported. The catalyst ionic liquid can be easily recycled and reused for at least five cycles without obvious loss of catalytic activity.