Distribution Of Active Components Research Articles

Investigation of coke deposition inside catalyst with heterogeneous active component distribution

Coke deposition over catalytic particles is not only associated with pore structure and pore distribution, but also depends on the active component distribution. A particle-resolved model is employed to explore the coke deposition process inside catalyst particles with heterogeneous active component distribution. The spatial and instantaneous distribution of coke deposition and its influence on catalytic performance in a single particle and a packed bed are evaluated. The results show that there is a weaker internal resistance of mass and heat transfer inside the egg-shell type catalyst so as to lead to a faster coke accumulation and catalyst deactivation, compared to the egg-yolk type catalyst. Meanwhile, the wall effect on coke accumulation is more significant for egg-yolk type catalysts.

Influence of impregnation conditions on the activity of CrOx/Al2O3 catalysts in dehydrogenation of isobutane in fixed bed reactor

The development of catalysts for dehydrogenation of light paraffin hydrocarbons in a fixed bed reactor is of great importance for the world petrochemical industry. The preparation of granules (~3 mm in diameter) of CrOx/Al2O3 catalysts is hindered by such problems as homogeneous distribution of active component and modifiers, high strength of granules, etc. In this paper, the alumina support dissolution in the impregnating solution containing chromic acid and the opportunity to apply vacuum impregnation to minimize this effect in the preparation of CrOx/Al2O3 catalysts are discussed. A series of catalysts is synthesized at different impregnation pressures (1, 0.85, and 0.7 atm), characterized by a complex of physical–chemical methods (low-temperature N2 adsorption, SEM, XRD, TPR-H2), and tested in isobutane dehydrogenation. The use of vacuum impregnation is shown to lead to the reduction of the specific surface area of the catalysts from to 91 to 56 m2/g and the growth of content of CrOx phases that decreases the catalytic activity in dehydrogenation. The isobutylene yield at 610 °C decreases from 68% to 54% for the catalyst prepared at P = 0.7 atm as compared with the one prepared at atmospheric pressure. The high activity and stability are connected with the hierarchical structure of the alumina support and homogeneous chromia distribution on its surface.

PHARMACOECONOMICAL ANALYSIS OF ANTI-PERIODONTOSIS DRUGS

In this work, a retrospective analysis of anti-periodontosis drugs is carried out using the methods of pharmacoeconomic analysis: analysis of the "cost of disease" (direct costs), "cost-effectiveness" for promoting the original drug "Matripin-Dent" on the pharmaceutical market. In the clinic of the Dental Institute of Kazakh National Medical University named after S.D. Asfendiyarov (Almaty), clinical trials of a new domestic phytopreparation “Dental gel Matripin-Dent” were carried out. The gel preparation was used in the complex therapy of periodontal diseases of an inflammatory and inflammatory-destructive nature. As a result of the experimental studies, it was found that "Matripin-Dent", due to the original composition of the gel composition, provides high adhesion to mucous surfaces, ensures reliable fixation of the drug on the gums, contributes to a better distribution of active components due to good absorption of the ointment base composition. It has been proven that the developed dosage form "Matripin-Dent" based on pharmacologically active compounds of Populus balsamifera L. buds and flowers, leaves, buds of Matricaria chamomilla L. has a number of advantages in comparison with the drugs existing on the pharmaceutical market used in dental practice.

Insight into the enhanced performance of toluene removal from simulated flue gas over Mn-Cu oxides modified activated coke

A series of bimetallic oxides of manganese and copper with different loading of copper loaded on activated coke (MnxCuy/AC) were synthesized by ultrasound-assisted equivalent volume impregnation method for toluene oxidation in simulated flue gas at 150–300 °C. The physicochemical properties of samples have been investigated by means of XRD, SEM, BET, XPS, H2-TPR and DRIFT. Mn6Cu5/AC exhibited the enhanced toluene removal efficiency (99.38%) at 270 °C, as well as satisfactory reusability and durability. The excellent activity of Mn6Cu5/AC was connected with the highly uniform distribution of active components and the larger specific surface area, which confirmed the synergistic interaction between MnOx and CuOx, thus leading to the stronger reducibility and the good oxygen mobility. In addition, SO2 and NO played a hindering role due to the competitive adsorption of active sites in pure N2, whereas the negative effect would be reduced by the introduction of O2. Besides, the influence of H2O on toluene removal was complex. Moreover, the reaction process obtained from DRIFT indicated that toluene can be rapidly adsorbed and activated to form the benzaldehyde and maleic anhydride species on Mn6Cu5/AC, and finally be further oxidized into CO2 and H2O. Finally, the mechanism of toluene oxidation over Mn6Cu5/AC was proposed.

Light‐Coded Digital Crystallinity Patterns Toward Bioinspired 4D Transformation of Shape‐Memory Polymers

AbstractSpatially heterogeneous distribution of active components is key to the diverse shape‐morphing behaviors of biological species and their associated functions. Artificial morphing materials employing similar strategies have widened the design space for advanced functional devices. Typically, the spatial heterogeneity is introduced during the material synthesis/fabrication step and cannot be altered afterward. An approach that allows spatio‐selective programming of crystallinity in a shape‐memory polymer (SMP) by a digital photothermal effect is reported. The light‐patternable crystallinity affects greatly the shape morphing behavior. Consequently, a pre‐stretched 2D film with spatial heterogeneity in crystallinity can morph with time into designable 3D permanent shapes, achieving the 4D transformation. This approach utilizes a reprocessible thermoplastic SMP (polylactide) and the programming relies on a physical phase transformation (crystallization) instead of chemical heterogeneity. This allows repeated erasing and reprogramming using the same material, suggesting a versatile and sustainable means for manufacturing advanced morphing devices.

Bimetallic Bifunctional Pt-NiP/Hβ as a Novel and Highly Efficient Catalyst for n-Hexane Isomerization

A novel bimetallic bifunctional Pt–NiP/Hβ isomerization catalyst was successfully prepared by introducing a small amount of noble metal Pt into the NiP on the Hβ carrier. The catalyst demonstrated superior catalytic activity to Pt/Hβ and NiP/Hβ catalysts for n-hexane isomerization, due to the good surface property, the synergistic effect of the two metals, the suitable match between acid site and metal site, as well as good reduction stability. The effects of Pt loading and NiP addition amount on the surface property were studied comprehensively through a series of characterization, and the correlation among surface property with catalytic behavior was also analyzed. The results indicated that the Pt (0.1 mol%)–NiP (10 mol%)/Hβ catalyst had good structural characters, surface acid property and an uniform distribution of NiP and Pt active components on surface, which is helpful to obtain a highly efficient catalytic performance. Additionally, the influence of reduction/reaction conditions on the catalytic activity, as well as the catalyst tolerance to water and thiophene sulfur, was investigated furtherly.

Tissue Distribution Comparison of Six Active Ingredients from an Eucommiae Cortex Extract between Normal and Spontaneously Hypertensive Rats.

Eucommiae Cortex (EC), a rare, nourishing medicinal herb that is native in China, has good effect in the treatment of hypertension. In this study, we compared tissue distribution of six representative active components of EC extract—genipinic acid (GA), protocatechuic acid (PCA), neochlorogenic acid (NCA), chlorogenic acid (CA), (+)-pinoresinol di-O-β-D-glucopyranoside (PDG), and (+)-pinoresinol 4′-O-β-D-glucopyranoside (PG)—between normal rats and spontaneously hypertensive rats (SHRs). Each rat was intragastrically given EC extract at a dose of 5.4 g/kg. Rats were sacrificed at 10 min, 30 min, 2 h, and 8 h after administration; six rats were sacrificed at each time point. Then, we quickly harvested their major organs, including heart, liver, spleen, lungs, kidneys, and brain. Using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), we determined the levels of the above mentioned six components in the organs of both types of rats and then analyzed differences in the tissue distribution. The results showed that levels of each component differed between SHRs and the normal group at each time point. As time progressed, the number of organs in which GA distribution in each tissue of SHRs differed from that of the normal group gradually increased: SHRs showed lower GA levels than normal rats. Levels of PG and PDG in both groups at 10 and 30 min were similar. NCA and CA in the SHR group and the normal group at 10 min, 30 min, and 2 h were also similar to some extent. The results indicated that the pathological state of spontaneous hypertension could affect tissue distribution of EC active components in rats.

Application of Fumed Silica as a Support during Oxidative Desulfurization.

Here, a hydrophilic fumed silica (F-SiO2) was used as a support, and we place phosphotungstic acid (HPW) onto the F-SiO2 via a simple impregnation method normally used to prepare a HPW/F-SiO2 catalyst, which is used in oxidative desulfurization processes. A number of characterization analyses were used, such as X-ray diffraction, Fourier transform infrared, and Transmission electron microscopy, to prove that the HPW catalyst was homogeneously distributed on the F-SiO2. The structural parameters of the catalyst and the support were tested with Brunauer–Emmett–Teller, and it was confirmed that the catalyst is a mesoporous material. Energy-dispersive spectrometry was used to characterize the distribution of the active component distribution. Catalytic performance was investigated using the catalytic oxidative desulfurization process. During optimal conditions, the removal effect of dibenzothiophene (DBT) in simulated oil can reach 100%. After 13 cycles, catalytic activity is still high, and the DBT conversion can still attain 95.362%.

Performance Analysis of Target Depth Classification Algorithm Based on Sea Experiment Data

Cross-spectrum signals can be calculated by the pressure signals. The sign distribution of cross-spectrum active component can be effectively used for target depth classification algorithm. The algorithm is applicable for depth classification of targets where frequencies can only excite the first two normal modes. The corresponding research results are mainly based on the theoretical study. There are few researches on the algorithm performance based on experiment results. To overcome this research lack, based on the effective depth model, the effects on various receiving depth, source frequency, and received signal-to-noise ratio on the algorithm performance have been studied in this paper. The influence of sound velocity profile parameters (negative gradient, thermocline intensity, thermocline thickness, and up-boundary depth) on the algorithm performance has also been researched. According to the simulation results, proper adjustment of the receiving depths can effectively improve the algorithm performance. The source frequency primarily affects the position of the ideal receiving depth which can be appropriately adjusted according to the depth classification requirements of the real sea environment. The algorithm performance improves gradually with the increase of signal-to-noise ratio. Moreover, the algorithm can also be applied under the conditions of negative gradient and thermocline. The comprehensive sound velocity profile parameters have a large impact on the depth classification performance of the algorithm. Even in the case of strong negative gradient or strong thermocline, the robustness of the algorithm is still high. The feasibility of our presented method has been verified by sea experiment. The practical application value of the ideal receiving depth has been researched and validated. The factors affecting the algorithm performance including line spectrum continuity and received signal-to-noise ratio have also been analyzed in our simulation and real sea experiments.

Removal of Elemental Mercury from Flue Gas Using Microwave/Ultrasound-Activated Ce–Fe Magnetic Porous Carbon Derived from Biomass Straw

Magnetic adsorbent shows good development prospects for separation of Hg0 from flue gas because it can be recycled. In this work, a novel magnetic biomass porous carbon adsorbent was developed by loading active ingredients (Ce and Fe mixed oxides) on renewable maize straw carbon with large specific surface area. Microwave activation and ultrasound treatment were applied to improve porous structure of maize straw carbon and distribution of active components. The influence of process parameters on Hg0 capture and the removal mechanism were also investigated. The results reveal that CeFe11%(3/5)/MSWU700 possesses the optimal Hg0 removing performance and adsorption capacity at 140 °C. The characterization results show that microwave activation can greatly increase the specific surface area of biomass carbon to form excellent porous structure, and ultrasound-assisted impregnation can facilitate the dispersion of active ingredients on the surface of adsorbent. The presence of Hg2+ on the surface of CeFe11%(3/5)...

Tissue distribution of main active components of Fagopyrum cymosum extracts in mice with ulcerative colitis

Tissue distribution of main active components of <i>Fagopyrum cymosum</i> extracts in mice with ulcerative colitis

Fabrication of silica supported Mn–Ce benzene oxidation catalyst by a simple and environment-friendly oxalate approach

A series of silica supported Mn–Ce composite oxides with different Mn/Ce molar ratios were obtained by a simple and environment-friendly oxalate route. The physical and chemical properties were characterized by TG, BET, SEM, TEM, XPS and TPR analysis. All catalysts showed excellent activity towards deep oxidation of benzene. The effects of Mn/Ce ratio, calcination temperature on the structure and catalytic activity of catalysts were investigated. Catalyst from nitrate precursor was also characterized to compare the influence of different precursors. The 6Mn4Ce sample from oxalate route sintered at 400 °C showed the maximum reaction rate of 0.50 mmol gcat−1h−1; T90 of the catalyst is 216 °C. The catalytic activity is related to surface area, pore size distribution, surface elemental species, particle size distribution and low temperature reducibility which may derived from synergistic effect between manganese and cerium oxide. Compared with nitrate precursors, catalyst from oxalate route can be more finely dispersed on the pores of silica without damaging the pore structure of support. The role of silica is not only a support, but also an in situ reaction site for precursor’s decomposition, which ensure the finely distribution of active components. In addition, the best catalyst showed good stability with prolonged time on stream.

μm- and nm-Sized Catalytic Structures in Heat Sources for Thermoelectric Generators.

Micro- and nano-structural organization and its influence on the efficiency of catalysts used in the heat sources for permeable thermoelectric generators were investigated. Two types of catalyst were studied–elemental platinum on aluminum oxide granulate Pt/Al₂O₃ and mixed transition-metal catalyst on fibrous silicon dioxide Co–Cr–Pd–Sr/SiO₂. The distribution of active components in catalytic structures which contribute to the maximum combustion completeness of organic fuel in heat sources was investigated. Practically full conversion of hydrocarbons was achieved already with 1 mass.% of platinum in the Pt/Al₂O₃ catalyst with sub-μm- and nm-sized particles placed at the input of the gas-air mixture into the channel of the permeable thermoelement. The propane-butane conversion rate of 97% for the catalyst Co–Cr–Pd/SiO₂ with was further enhanced by addition of 0.5 mass.% of Sr. The catalytic centers are formed by CoCr₂O₄ nanocrystals (10 to 40 nm in size) with Pd promotor in form of single crystals on the fibrous SiO₂ matrix.

CoMoNi Catalyst Texture and Surface Properties in Heavy Oil Processing. Part II: Macroporous Sepiolite-Like Mineral

A set of novel CoMoNi hydrotreating catalysts supported on sepiolite-like mineral and modified by H3PO4 have been prepared and studied in hydrodesulfurization (HDS) and hydrodemetallization (HDM) of heavy Tatar oil with extremely high viscosity and sulfur content. Catalysts had a multiphase composition, represented by calcium/magnesium oxides, silicates, or phosphates, and were found to be of great interest for studying the role of support surface properties in heavy oil hydrotreating. For monitoring the catalyst properties, all the samples have been investigated by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XFS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), CO- and CDCl3-Fourier transform infrared (FTIR), mercury porosimetry, and N2 adsorption methods. The catalyst with a small phosphate content showed higher initial HDS conversion due to the more developed specific surface area, increased Lewis acidity, and better active component distribution; however, ...

CRF receptor 1 antagonism and brain distribution of active components contribute to the ameliorative effect of rikkunshito on stress-induced anorexia.

Rikkunshito (RKT), a Kampo medicine, has been reported to show an ameliorative effect on sustained hypophagia after novelty stress exposure in aged mice through serotonin 2C receptor (5-HT2CR) antagonism. We aimed to determine (1) whether the activation of anorexigenic neurons, corticotropin-releasing factor (CRF), and pro-opiomelanocortin (POMC) neurons, is involved in the initiation of hypophagia induced by novelty stress in aged mice; (2) whether the ameliorative effect of RKT is associated with CRF and POMC neurons and downstream signal transduction; and (3) the plasma and brain distribution of the active components of RKT. The administration of RKT or 5-HT2CR, CRF receptor 1 (CRFR1), and melanocortin-4 receptor antagonists significantly restored the decreased food intake observed in aged male C57BL/6 mice in the early stage after novelty stress exposure. Seven components of RKT exhibited antagonistic activity against CRFR1. Hesperetin and isoliquiritigenin, which showed antagonistic effects against both CRFR1 and 5-HT2CR, were distributed in the plasma and brain of male Sprague-Dawley rats after a single oral administration of RKT. In conclusion, the ameliorative effect of RKT in this model is assumed to be at least partly due to brain-distributed active components possessing 5-HT2CR and CRFR1 antagonistic activities.

Effect of temperature-programmed pyrolysis pre-treatment on desulfurization performance of Zn-based sorbent prepared by lignite as support

A series of Zn-based sorbents were prepared by high-pressure impregnation with lignite as precursor of support and zinc nitrate as the precursor of active component, followed by temperature-programmed pyrolysis of the impregnated lignite sample in a fixed-bed quartz reactor. The H2S removal performances of sorbents prepared under different pyrolysis conditions such as temperatures, holding time as well as heating rates were evaluated. The physical and chemical properties of sorbents were characterized by atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), transmission electron microscope (TEM) and nitrogen adsorption techniques. The results show that the process of pyrolysis can improve the pore structure dramatically, which lead to the high specific surface area and large pore volume. The good desulfurization performance of sorbent was attributed to both of the proper porous structure of sorbents, the content and distribution of active component. The optimal operating conditions of temperature-programmed pyrolysis for the impregnated lignite sample were the heating rate of 10°C/min, holding time of 180min in N2 atmosphere and pyrolysis temperature of 550°C. The sulfidation time could hold for over 720min before reaching 1ppm H2S in outlet gases and the sulfur capacity was up to 25.91g S/100g ZnO for sorbent prepared under this optimized condition.

Mutational Analysis of Rab3 Function for Controlling Active Zone Protein Composition at the Drosophila Neuromuscular Junction.

At synapses, the release of neurotransmitter is regulated by molecular machinery that aggregates at specialized presynaptic release sites termed active zones. The complement of active zone proteins at each site is a determinant of release efficacy and can be remodeled to alter synapse function. The small GTPase Rab3 was previously identified as playing a novel role that controls the distribution of active zone proteins to individual release sites at the Drosophila neuromuscular junction. Rab3 has been extensively studied for its role in the synaptic vesicle cycle; however, the mechanism by which Rab3 controls active zone development remains unknown. To explore this mechanism, we conducted a mutational analysis to determine the molecular and structural requirements of Rab3 function at Drosophila synapses. We find that GTP-binding is required for Rab3 to traffick to synapses and distribute active zone components across release sites. Conversely, the hydrolytic activity of Rab3 is unnecessary for this function. Through a structure-function analysis we identify specific residues within the effector-binding switch regions that are required for Rab3 function and determine that membrane attachment is essential. Our findings suggest that Rab3 controls the distribution of active zone components via a vesicle docking mechanism that is consistent with standard Rab protein function.

Comparative analysis of 1-deoxynojirimycin contribution degree to α-glucosidase inhibitory activity and physiological distribution in Morus alba L

Natural α-glucosidase inhibitors offer an attractive strategy to manage postprandial hyperglycemia in patients with type 2 diabetes. 1-Deoxynojirimycin (DNJ), the main hypoglycemic constituents in Morus alba L., has been extensively researched. Here, for different parts of the mulberry tree, the DNJ content and the IC50 values of DNJ and ethanol extracts have been determined and compared. Possible metabolic pathways and storage sites for DNJ in mulberry trees have been investigated, and the kinetics of inhibition of α-glucosidase by DNJ and ethanol extracts of different parts of the mulberry tree have been measured. DNJ content was found to be highest in trunk bark, whereas α-glucosidase inhibitory activity was highest in both twig and trunk bark. Buds and roots are likely to be the topmost and bottommost sites of DNJ biosynthesis. DNJ is an insect antifeedant (not including silkworms) and may itself have antiviral activity, or be the precursor to a compound with antiviral activity. Ethanol extracts of twig, trunk and root bark are mixed-type inhibitors of α-glucosidase; extracts from other parts of the tree are competitive inhibitors. The study provides useful information about the physiological distribution of important active components, especially DNJ, in the mulberry tree and suggests how best to develop and use the crude drug resources provided by the tree.

Influences of exhaust gas temperature and flow rate on optimal catalyst activity profiles

This paper presents an optimization of an axial catalyst distribution for the two types of optimal axial catalyst distributions: continuous exponential and discrete two-zone, to enhance the light-off of a catalytic converter with a fixed amount of a catalyst. The influences of exhaust gas temperature and mass flow rate on the two types of optimal active component distribution profiles are identified and hence an optimum value for each of the operating conditions is quantitatively established. The catalyst surface area of the optimal distribution in the upstream section is greater, and in the downstream is lower than that of the uniform distribution. As an inlet exhaust gas temperature becomes lower than the catalyst light-off temperature, i.e., about 600K, the catalyst surface area of the optimal distribution at the monolith inlet increases greatly to attain high reaction rates at the monolith entrance. In contrast, at temperatures above 600K, it decreases slightly and hence its variation becomes negligibly small, as compared to the variation of the inlet gas temperature. The catalyst surface area at the monolith entrance decreases gradually with the increasing mass flow rate at gas temperatures above 550K.

In vivo distribution and pharmacokinetics of multiple active components from Danshen and Sanqi and their combination via inner ear administration

Ethnopharmacological relevanceSalvia miltiorrhiza Bunge (Labiatae sp. plant, Chinese name Danshen) and Panax notoginseng (Burk.) F. H. Chen (Araliaceae plant, Chinese name Sanqi) have a long history in treating coronary heart disease, cerebrovascular disease and inner ear disorders in traditional Chinese medicine. To provide a rational basis for the use of these herbs in clinical practice, we investigated the in vivo distribution and pharmacokinetics of marker agents in Danshen and Sanqi via intravenous and inner ear administration and explored the potential interactions of these agents in compound prescription. Materials and methodsGuinea pigs were given Danshen extracts (salvianolic acid B, tanshinone IIA), Sanqi extracts (Panax notoginseng saponins) and combination of the two extracts via intravenous and intratympanic administration (IT). Samples from the brain, inner ear perilymph (PL), cerebrospinal fluid (CSF) and plasma were collected at different time points. The concentration of salvianolic acid B (Sal B), tanshinone IIA (Ts IIA), notoginsenoside R1 (R1), ginsenoside Rg1 (Rg1) and ginsenoside Rb1 (Rb1) was determined by high-performance liquid chromatography coupled with a diode array detector (DAD). Pharmacokinetic parameters were estimated using non-compartmental methods. ResultsLocal drug application via inner ear greatly improved drug distribution within the PL, CSF and brain tissues compared with intravenous administration (IV). The values of Cmax and AUC(0–t) after IT were significantly higher than IV. In comparison with IT of Danshen and Sanqi alone, the pharmacokinetic parameters for R1, Rg1, Rb1, Sal B and Ts IIA were markedly different in the compound prescription. The compound compatibility enhanced the transport of Danshen components into the brain through the inner ear and apparently prolonged the retention time in CSF while decreasing the distribution of Sanqi components in the inner ear and brain. ConclusionsThe results indicated that local drug application to the inner ear was a more effective delivery route than systemic administration. Co-administration of Danshen and Sanqi could cause significant pharmacokinetic herb–herb interactions in guinea pigs. The multiple active components via inner ear administration might be promising candidates for the treatment of inner ear and brain diseases.