The development and delivery of high quality therapeutic products necessitates the need for highthrough-put (HTP) process development tools. Traditionally, these works requires a combination of shake flask and small-s...The development and delivery of high quality therapeutic products necessitates the need for highthrough-put (HTP) process development tools. Traditionally, these works requires a combination of shake flask and small-scale stirred tank bioreactor (STR) which are labor and resource intensive and time-consuming. Here we demonstrate a strategy for rapid and robust cell culture process development by evaluating and implementing the use of a new HTP disposable micro bioreactor (MBR) called AMBRTM system (Advanced Microscale Bioreactor) that has the capabilities for automated sampling, feed addition, pH, dissolved oxygen (DO), gassing and agitation controls. In these studies the performance of two monoclonal antibody (MAb) producing cell lines (MAb1 and MAb2) was evaluated both in the AMBR system and 3-L STR. We demonstrated that cell culture performance (growth and viability, production titer and product quality) were similar in both vessel systems. Furthermore, process control and feed optimization were demonstrated in an additional cell line (MAb3) in the disposable MBR and its performance confirmed at STR scale. The results indicate that the AMBR system can be used to streamline the process development effort and facilitate a rapid and robust cell culture process development effort for MAb programs in a HTP manner.展开更多
Racotumomab monoclonal antibody is a murine anti-idiotypic antibody. This monoclonal antibody mimics N-glycolyl-GM3 gangliosides has been tested in several clinical trials Phase I/II for breast, melanoma and non-small...Racotumomab monoclonal antibody is a murine anti-idiotypic antibody. This monoclonal antibody mimics N-glycolyl-GM3 gangliosides has been tested in several clinical trials Phase I/II for breast, melanoma and non-small cell lung cancer patients as an anti-idiotypic cancer vaccine. The early production process was performed in vivo from mice ascites fluid. This process was transferred to bioreactor-based method at pilot scale followed to the scale-up of the fermentation. In this work we present a comprehensive molecular characterization of racotumomab MAb produced by the two different production scales in order to determine the impact of the manufacturing process in vaccine performance. We observed differences in glycosylation pattern and charge heterogeneity between racotumomab produced in both scales. Interestingly, these modifications had no significant impact on biological activity elicited in chickens. So, changes in primary structure like glycosylation, charge heterogeneity and oxidation did not affect biological activity of the vaccine.展开更多
True Boiling Point （TBP） distillation is one of the most common experimental techniques for determination of petroleum properties. The methods for performing TBP distillation experiments are described by ASTM D2892 ...True Boiling Point （TBP） distillation is one of the most common experimental techniques for determination of petroleum properties. The methods for performing TBP distillation experiments are described by ASTM D2892 and by ASTM D5236. However, these methods are established for petroleum fractions that reach temperatures up to 565 ~C. In this work, two petroleum residues were distilled in a falling film molecular distillation prototype and the data were used to obtain the extension of the TBP curve above a temperature of 565 ~C. It was possible to extend the TBP curve of both petroleum up to temperatures close to 700 ~C with consistency and continuity in comparison to the standard curve. In addition, an amount of raw material that was been treated as residue could be reused.展开更多
Aluminum based metal matrix composites were fabricated using stir casting where silicon carbide and alumina were the reinforcements. Different types of properties (physical-density, mechanical-tensile, hardness, chemi...Aluminum based metal matrix composites were fabricated using stir casting where silicon carbide and alumina were the reinforcements. Different types of properties (physical-density, mechanical-tensile, hardness, chemical-corrosion etc.) were measured and compared with base metals/alloys. The properties were significantly varied. The highest density was obtained for pure aluminium with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for AA-4032 alloy. The highest hardness was obtained for AA-4032 with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for pure Al with 5% Al<sub>2</sub>O<sub>3</sub>. The highest strength was obtained for AA-6061 with 5% coarse SiC whereas the lowest was obtained for pure Al. The highest impact strength was obtained for AA-4032 with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for AA-6061. The corrosion resistance of all composites was lower than that of the base materials.展开更多
As interconnects shrink beyond 90nm node, the presence of etch residues can createhigh via resistance and void nucleation during stress migration (SM) testing. Physical Ar+ preclean is effectivein removing residues, b...As interconnects shrink beyond 90nm node, the presence of etch residues can createhigh via resistance and void nucleation during stress migration (SM) testing. Physical Ar+ preclean is effectivein removing residues, but early SM failures have been seen due to Cu resputter from underlying trenches.Reactive preclean methods show promise in reducing CuOx and cleaning Si, N, F, C,O etch residues inpresence of H+, H* species. In this paper, reactive preclean and PVD PunchThru process (deposit-etch-deposit) is proposed as solution to conventional PVD.The PunchThru process reduces via resistance, improves SM and protects dual-damascene beveland unlanded vias from Cu diffusion by presence of thin Ta deposition step. In addition, the U-shaped interface,which minimizes electron crowding and localized heating effects, increases the mean time to failureby electromigration. Consistent, repeatable blanket film property and good parametric electrical test resultshave proven the production worthiness of this process.展开更多
Calcium-based biocomposite materials have a pivotal role in the biomedical field with their diverse properties and applications in combating challenging medical problems. The study states the development and character...Calcium-based biocomposite materials have a pivotal role in the biomedical field with their diverse properties and applications in combating challenging medical problems. The study states the development and characterization of Calcium-based biocomposites: Hydroxyapatite (HAP), and PVA-Gelatin-HAP films. For the preparation of Calcium-based biocomposites, an unconventional source, the waste material calcite stone, was used as calcium raw material, and by the process of calcination, calcium oxide was synthesized. From calcium oxide, HAP was prepared by chemical precipitation method, which was later added in different proportions to PVA-Gelatin solution and finally dried to form biocomposite films. Then the different properties of PVA/Gelatin/HAP composite, for instance, chemical, mechanical, thermal, and swelling properties due to the incorporation of various proportions of HAP in PVA-Gelatin solution, were investigated. The characterization of the HAP was conducted by X-ray Diffraction Analysis, and the characterization of HAP-PVA-Gelatin composites was done by Fourier Transform Infrared Spectroscopy, Thermomechanical Analysis, Tensile test, Thermogravimetric Differential Thermal Analysis, and Swelling Test. The produced biocomposite films might have applications in orthopedic implants, drug delivery, bone tissue engineering, and wound healing.展开更多
When sinters are filled into the sinter cooler from the sintering machine, it is commonly seen that, due to segregation effects, sinters of larger size usually accumulate closer to the inner wall of the sinter cooler,...When sinters are filled into the sinter cooler from the sintering machine, it is commonly seen that, due to segregation effects, sinters of larger size usually accumulate closer to the inner wall of the sinter cooler, whereas those of smaller size are to the outer wall. This nonuniform distribution of sinters has led to uneven cooling effect throughout the cooler. This causes the sinters leaving the cooler at a large temperature difference. This undesired temperature difference leads to the deformation and even the destruction of the conveyors. The computational fluid dynamics （CFD） technique was used in the present work to investigate the heat and fluid flow phenomena within the sinter cooler corresponding to the different distribution of sinter layer porosity, which was highly dependent on the arrangement and orientation of sinters within the sinter cooler. It is confirmed that a high mass flow rate within the sinter layer causes a low temperature region and vice versa. The flow fields for vertically reducing porosity distribution and random distribution are almost identical indicating the relative insignificance of convective heat transfer mechanism.展开更多
Toluene was alkylated with methanol in a flow type reactor at temperatures between 300 and 500 °C using H-ZSM-5 zeolite, 0.2%Pt/H-ZSM-5 and hydrofluorinated 0.2%Pt/H-ZSM-5 with HF concentrations of 1.0%, 2.0%, 3....Toluene was alkylated with methanol in a flow type reactor at temperatures between 300 and 500 °C using H-ZSM-5 zeolite, 0.2%Pt/H-ZSM-5 and hydrofluorinated 0.2%Pt/H-ZSM-5 with HF concentrations of 1.0%, 2.0%, 3.0%, or 4.0%. Pt primarily enhances toluene conversion, total xylenes production, and p-xylene relative to its thermodynamic equilibrium. As the concentration of HF increases from 1.0% to 3.0%, the catalyst activity increases because of the increase in the number of acid sites and their strength. Additionally, the surface area and Pt dispersion also increases. An advantage of increased HF doping is that the formation of voluminous trimethylbenzene (TMB) byproducts is inhibited. However, at a HF concentration of 4.0%, Al and Si are partially leached and then deposited mostly in the wider catalytic pores. This was determined by evaluating the pore volume distribution and we determined that reactivity inhibition was ob-viously present and was due to diffusion restriction.展开更多
The most prestigious catalyst applied in natural gas （methane） non-oxidative conversion to petrochemicals is 6%Mo/H-ZSM-5. Chromium, molybdenum and tungsten are the group VI metals. Hence, in this work, 6%Mo/H-ZSM-5...The most prestigious catalyst applied in natural gas （methane） non-oxidative conversion to petrochemicals is 6%Mo/H-ZSM-5. Chromium, molybdenum and tungsten are the group VI metals. Hence, in this work, 6%Mo/H-ZSM-5 was correlated with 3%Cr＋3%Mo/H-ZSM-5 and 3%W＋3%Mo/H-ZSM-5 as catalysts to examine their promoting or inhibiting effects on the various reactions taking place during methane conversion. The catalytic activities of these catalysts were tested in a continuous flow fixed bed reactor at 700℃ and a GHSV of 1500 ml·g^-1·h^-1 Characterization of the catalysts using XRD, TGA and TPD were investigated. XRD and NH3-TPD showed greater interaction between the W-phase and the Bronsted acid sites in the channels of the zeolite than between Cr-phase and the acid sites in the zeolite.展开更多
Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidat...Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidative coupling of methane （OCM） to higher hydrocarbons at different reaction conditions （viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm^3 ·g^-1·h^-1） have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties （viz. surface area, basicity/base strength distribution） and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity （strong basic sites） and the C2＋ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO （Na/Ca = 0.1, before calcination） catalyst （calcined at 750 ℃）, showed best performance （C2＋ selectivity of 68.8% with 24.7% methane conversion）, whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.展开更多
In the current work,molecular dynamics simulation is employed to understand the intrinsic growth of carbon dioxide and methane hydrate starting from a seed crystal of methane and carbon dioxide respectively.This compa...In the current work,molecular dynamics simulation is employed to understand the intrinsic growth of carbon dioxide and methane hydrate starting from a seed crystal of methane and carbon dioxide respectively.This comparison was carried out because it has relevance to the recovery of methane gas from natural gas hydrate reservoirs by simultaneously sequestering a greenhouse gas like CO2.The seed crystal of carbon dioxide and methane hydrate was allowed to grow from a super-saturated mixture of carbon dioxide or methane molecules in water respectively.Two different concentrations(1:6 and 1:8.5)of CO2/CH4 molecules per water molecule were chosen based on gas–water composition in hydrate phase.The molecular level growth as a function of time was investigated by all atomistic molecular dynamics simulation under suitable temperature and pressure range which was well above the hydrate stability zone to ensure significantly faster growth kinetics.The concentration of CO2 molecules in water played a significant role in growth kinetics,and it was observed that maximizing the CO2 concentration in the aqueous phase may not result in faster growth of CO2 hydrate.On the contrary,methane hydrate growth was independent of methane molecule concentration in the aqueous phase.We have validated our results by performing experimental work on carbon dioxide hydrate where it was seen that under conditions appropriate for liquid CO2,the growth for carbon dioxide hydrate was very slow in the beginning.展开更多
This scale-up study demonstrated the feasibility of an ionic liquid(IL)pretreatment process at 40 kg scale,using the IL 1-ethyl-3-methylimidazolium acetate([C2C1Im][OAc])as the solvent.The pretreatment was followed by...This scale-up study demonstrated the feasibility of an ionic liquid(IL)pretreatment process at 40 kg scale,using the IL 1-ethyl-3-methylimidazolium acetate([C2C1Im][OAc])as the solvent.The pretreatment was followed by enzymatic hydrolysis through which the process efficiency for biomass conversion to monomeric sugars was determined.The results show that 43 wt%of switchgrass was dissolved in IL after 2 h of pretreatment at 160℃ with 15 wt%solid loading.A 120 h enzymatic hydrolysis of the pretreated switchgrass results in 96%glucan and 98%xylan conversion.[C2C1Im][OAc]pretreatment has been successfully scaled up to 40 kg with improved sugar titers and yields relative to bench scale(6 kg).The mass flow of the overall process was established and the major scale-up challenges of the process were identified.展开更多
Natural gas conversion to petrochemicals, principally, benzene, naphthalene, toluene, as well as ethylene under non-oxidative conditions was examined in a fixed bed flow reactor at 700 ℃ and gaseous hourly space velo...Natural gas conversion to petrochemicals, principally, benzene, naphthalene, toluene, as well as ethylene under non-oxidative conditions was examined in a fixed bed flow reactor at 700 ℃ and gaseous hourly space velocity （GHSV） of 1500 ml·g ^-1·h^-1 at time-on-stream ranging from 5 rain to 4 h using catalysts containing 6.0%Mo/H-ZSM-5 promoted with Pd or Ir metal. The catalysts were characterized by XRD, TPD, and TGA. The addition of Pd or Ir to 6%Mo/H-ZSM-5 catalyst promoted ethylene production but inhibited the cyclization reaction to aromatics owing to the strong interaction between these noble metals and the framework Al species, which were attached to the acid sites during the impregnation process. Coke deposition on the catalysts was found to decrease upon addition of 0.5wt% of Pd or Ir to 6%Mo/H-ZSM-5 catalyst owing to the hydrogenating activity of these metals.展开更多
Alkaline earth metal （Mg,Ca,Sr and Ba）-doped Mo-V-Sb-O x catalysts,prepared by a dry-up method,have been investigated for their catalytic performance in the oxidation of propane under different reaction conditions.T...Alkaline earth metal （Mg,Ca,Sr and Ba）-doped Mo-V-Sb-O x catalysts,prepared by a dry-up method,have been investigated for their catalytic performance in the oxidation of propane under different reaction conditions.The catalysts have been characterized by N2 adsorption-desorption,temperature-programmed desorption （TPD） of NH3,SEM and XRD.Influence of water vapor on the catalytic performance,particularly on the selectivities to acetic acid and acrylic acid,has also been studied.The selectivity to acrylic acid was improved significantly by the doping of alkaline earth metals to Mo-V-Sb-O x catalysts.The surface acidic sites of the catalyst decreased with the doping of the catalyst with alkaline earth metals,which ultimately was found to be beneficial for obtaining high selectivity to acrylic acid.The catalytic activity and product selectivities were found to be influenced by the reaction temperature,C3H8/O2 ratio and space velocity.A significant improvement in the selectivity to acrylic acid has also been observed by the addition of water vapor in the feed of propane and oxygen in the oxidation of propane.展开更多
Extended use of supported Pt catalysts causes thermal migration of Pt particles to form large agglomerates,thus decreasing the catalytic activity.The combination of Pt with Re protects Pt against migration.In addition...Extended use of supported Pt catalysts causes thermal migration of Pt particles to form large agglomerates,thus decreasing the catalytic activity.The combination of Pt with Re protects Pt against migration.In addition,Cl injection into the reactor assists Pt particles redispersion to prolong catalyst life.In this work,a PtRe/H-ZSM-5 catalyst was treated with either HCl or HF to investigate their role in activating or deactivating the catalyst.The conversion exceeded 90% in the whole temperature range with the PtRe/H-ZSM-5(HCl) catalyst,and its activity for the direct isomerization of cyclohexene to methylcyclopentenes(MCPEs) was the lowest but the activity for the hydrogenation of the MCPEs to methylcyclopentane was the highest.The reactivities of MCPEs and cyclohexadienes on the catalysts were similar because both are dehydrogenation reactions.Benzene production was significantly higher on the hydrochlorinated catalyst than on the other catalysts,and its hydrocracking activity was the lowest,which is a good characteristic for processing catalysts where cracking is undesired.展开更多
Oxidation reaction of rare earth chlorides(Ce/Pr/Nd/EuCl3) in a LiCl-KCl eutectic molten salt was carried out using an oxygen sparging method. Regardless of the sparging time and the molten salt temperature, oxychlori...Oxidation reaction of rare earth chlorides(Ce/Pr/Nd/EuCl3) in a LiCl-KCl eutectic molten salt was carried out using an oxygen sparging method. Regardless of the sparging time and the molten salt temperature, oxychlorides (NdOCl, PrOCl) and oxides(CeO, Eu2O3, PrO2) were formed as a oxidation products(i.e. precipitates) by the reaction with oxygen. The conversion efficiency of the rare earth elements to the precipitates increases with the sparging time and the molten salt temperature. In the conditions of 650 ℃ of a molten salt temperature and 420 min of a sparging time, the values of the conversion efficiency of the used rare earth chlorides were over 99.9%. Information on the hydrodynamics of an oxygen-molten salt two phase flow system is essential since its hydrodynamics strongly affect the oxidation reaction of rare earth elements in an eutectic chloride melts.展开更多
In this work, the effects of injecting an evaporating liquid jet into solid-gas flow are experimentally investigated. A new model （SHED model） and a supplementary model （spray model） have also been proposed to inv...In this work, the effects of injecting an evaporating liquid jet into solid-gas flow are experimentally investigated. A new model （SHED model） and a supplementary model （spray model） have also been proposed to investigate some flow-field characteristics in three-phase fluidized bed with the mean relative error 4.3% between model and measured results. Some experiments were conducted to study the influences of flow-field parameters such as liquid volumetric flow rate, injection velocity, jet angle and gas superficial velocity as well as solid mass flux on the jet penetration depth （JPD）. In addition, independent variables were experimentally employed to propose two empirical correlations for JPD by using multiple regression method and spray cone angle （SCA） by using dimensional analysis technique. The mean relative errors between the JPD and SCA correlations versus ex- perimental data were 7.5% and 3.9%, respectively. In addition, in order to identify the variable effect, a parametric study was carried out. Applying the proposed model can avoid direct use of expensive devices to measureJPD and to nredict dronlet size.展开更多
In the coal-based combustion and gasification processes, the mineral matter contained in the coal (predominantly oxides), is left as an incombustible residue, termed ash. Commonly, ash deposits are formed on the heat ...In the coal-based combustion and gasification processes, the mineral matter contained in the coal (predominantly oxides), is left as an incombustible residue, termed ash. Commonly, ash deposits are formed on the heat absorbing surfaces of the exposed equipment of the combustion/gasification processes. These deposits lead to the occurrence of slagging or fouling and. consequently, reduced process efficiency. The ash fusion temperatures (AFTs) signify the temperature range over which the ash deposits are formed on the heat absorbing surfaces of the process equipment. Thus, for designing and operating the coal-based processes, it is important to have mathematical models predicting accurately the four types of AFTs namely initial deformation temperature, softening temperature, hemispherical temperature, and flow temperature. Several linear/nonlinear models with varying prediction accuracies and complexities are available for the AFT prediction. Their principal drawback is their applicability to the coals originating from a limited number of geographical regions. Accordingly, this study presents computational intelligenee (CI) based nonlinear models to predict the four AFTs using the oxide composition of the coal ash as the model input. The CI methods used in the modeling are genetic programming (GP), artificial neural networks, and support vector regression. The no table features of this study are that the models with a better AFT prediction and generalization performanee, a wider application potential, and reduced complexity, have been developed. Among the Ci-based models, GP and MLP based models have yielded overall improved performanee in predicting all four AFTs.展开更多
文摘The development and delivery of high quality therapeutic products necessitates the need for highthrough-put (HTP) process development tools. Traditionally, these works requires a combination of shake flask and small-scale stirred tank bioreactor (STR) which are labor and resource intensive and time-consuming. Here we demonstrate a strategy for rapid and robust cell culture process development by evaluating and implementing the use of a new HTP disposable micro bioreactor (MBR) called AMBRTM system (Advanced Microscale Bioreactor) that has the capabilities for automated sampling, feed addition, pH, dissolved oxygen (DO), gassing and agitation controls. In these studies the performance of two monoclonal antibody (MAb) producing cell lines (MAb1 and MAb2) was evaluated both in the AMBR system and 3-L STR. We demonstrated that cell culture performance (growth and viability, production titer and product quality) were similar in both vessel systems. Furthermore, process control and feed optimization were demonstrated in an additional cell line (MAb3) in the disposable MBR and its performance confirmed at STR scale. The results indicate that the AMBR system can be used to streamline the process development effort and facilitate a rapid and robust cell culture process development effort for MAb programs in a HTP manner.
文摘Racotumomab monoclonal antibody is a murine anti-idiotypic antibody. This monoclonal antibody mimics N-glycolyl-GM3 gangliosides has been tested in several clinical trials Phase I/II for breast, melanoma and non-small cell lung cancer patients as an anti-idiotypic cancer vaccine. The early production process was performed in vivo from mice ascites fluid. This process was transferred to bioreactor-based method at pilot scale followed to the scale-up of the fermentation. In this work we present a comprehensive molecular characterization of racotumomab MAb produced by the two different production scales in order to determine the impact of the manufacturing process in vaccine performance. We observed differences in glycosylation pattern and charge heterogeneity between racotumomab produced in both scales. Interestingly, these modifications had no significant impact on biological activity elicited in chickens. So, changes in primary structure like glycosylation, charge heterogeneity and oxidation did not affect biological activity of the vaccine.
文摘True Boiling Point （TBP） distillation is one of the most common experimental techniques for determination of petroleum properties. The methods for performing TBP distillation experiments are described by ASTM D2892 and by ASTM D5236. However, these methods are established for petroleum fractions that reach temperatures up to 565 ~C. In this work, two petroleum residues were distilled in a falling film molecular distillation prototype and the data were used to obtain the extension of the TBP curve above a temperature of 565 ~C. It was possible to extend the TBP curve of both petroleum up to temperatures close to 700 ~C with consistency and continuity in comparison to the standard curve. In addition, an amount of raw material that was been treated as residue could be reused.
文摘Aluminum based metal matrix composites were fabricated using stir casting where silicon carbide and alumina were the reinforcements. Different types of properties (physical-density, mechanical-tensile, hardness, chemical-corrosion etc.) were measured and compared with base metals/alloys. The properties were significantly varied. The highest density was obtained for pure aluminium with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for AA-4032 alloy. The highest hardness was obtained for AA-4032 with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for pure Al with 5% Al<sub>2</sub>O<sub>3</sub>. The highest strength was obtained for AA-6061 with 5% coarse SiC whereas the lowest was obtained for pure Al. The highest impact strength was obtained for AA-4032 with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for AA-6061. The corrosion resistance of all composites was lower than that of the base materials.
文摘As interconnects shrink beyond 90nm node, the presence of etch residues can createhigh via resistance and void nucleation during stress migration (SM) testing. Physical Ar+ preclean is effectivein removing residues, but early SM failures have been seen due to Cu resputter from underlying trenches.Reactive preclean methods show promise in reducing CuOx and cleaning Si, N, F, C,O etch residues inpresence of H+, H* species. In this paper, reactive preclean and PVD PunchThru process (deposit-etch-deposit) is proposed as solution to conventional PVD.The PunchThru process reduces via resistance, improves SM and protects dual-damascene beveland unlanded vias from Cu diffusion by presence of thin Ta deposition step. In addition, the U-shaped interface,which minimizes electron crowding and localized heating effects, increases the mean time to failureby electromigration. Consistent, repeatable blanket film property and good parametric electrical test resultshave proven the production worthiness of this process.
文摘Calcium-based biocomposite materials have a pivotal role in the biomedical field with their diverse properties and applications in combating challenging medical problems. The study states the development and characterization of Calcium-based biocomposites: Hydroxyapatite (HAP), and PVA-Gelatin-HAP films. For the preparation of Calcium-based biocomposites, an unconventional source, the waste material calcite stone, was used as calcium raw material, and by the process of calcination, calcium oxide was synthesized. From calcium oxide, HAP was prepared by chemical precipitation method, which was later added in different proportions to PVA-Gelatin solution and finally dried to form biocomposite films. Then the different properties of PVA/Gelatin/HAP composite, for instance, chemical, mechanical, thermal, and swelling properties due to the incorporation of various proportions of HAP in PVA-Gelatin solution, were investigated. The characterization of the HAP was conducted by X-ray Diffraction Analysis, and the characterization of HAP-PVA-Gelatin composites was done by Fourier Transform Infrared Spectroscopy, Thermomechanical Analysis, Tensile test, Thermogravimetric Differential Thermal Analysis, and Swelling Test. The produced biocomposite films might have applications in orthopedic implants, drug delivery, bone tissue engineering, and wound healing.
文摘When sinters are filled into the sinter cooler from the sintering machine, it is commonly seen that, due to segregation effects, sinters of larger size usually accumulate closer to the inner wall of the sinter cooler, whereas those of smaller size are to the outer wall. This nonuniform distribution of sinters has led to uneven cooling effect throughout the cooler. This causes the sinters leaving the cooler at a large temperature difference. This undesired temperature difference leads to the deformation and even the destruction of the conveyors. The computational fluid dynamics （CFD） technique was used in the present work to investigate the heat and fluid flow phenomena within the sinter cooler corresponding to the different distribution of sinter layer porosity, which was highly dependent on the arrangement and orientation of sinters within the sinter cooler. It is confirmed that a high mass flow rate within the sinter layer causes a low temperature region and vice versa. The flow fields for vertically reducing porosity distribution and random distribution are almost identical indicating the relative insignificance of convective heat transfer mechanism.
文摘Toluene was alkylated with methanol in a flow type reactor at temperatures between 300 and 500 °C using H-ZSM-5 zeolite, 0.2%Pt/H-ZSM-5 and hydrofluorinated 0.2%Pt/H-ZSM-5 with HF concentrations of 1.0%, 2.0%, 3.0%, or 4.0%. Pt primarily enhances toluene conversion, total xylenes production, and p-xylene relative to its thermodynamic equilibrium. As the concentration of HF increases from 1.0% to 3.0%, the catalyst activity increases because of the increase in the number of acid sites and their strength. Additionally, the surface area and Pt dispersion also increases. An advantage of increased HF doping is that the formation of voluminous trimethylbenzene (TMB) byproducts is inhibited. However, at a HF concentration of 4.0%, Al and Si are partially leached and then deposited mostly in the wider catalytic pores. This was determined by evaluating the pore volume distribution and we determined that reactivity inhibition was ob-viously present and was due to diffusion restriction.
文摘The most prestigious catalyst applied in natural gas （methane） non-oxidative conversion to petrochemicals is 6%Mo/H-ZSM-5. Chromium, molybdenum and tungsten are the group VI metals. Hence, in this work, 6%Mo/H-ZSM-5 was correlated with 3%Cr＋3%Mo/H-ZSM-5 and 3%W＋3%Mo/H-ZSM-5 as catalysts to examine their promoting or inhibiting effects on the various reactions taking place during methane conversion. The catalytic activities of these catalysts were tested in a continuous flow fixed bed reactor at 700℃ and a GHSV of 1500 ml·g^-1·h^-1 Characterization of the catalysts using XRD, TGA and TPD were investigated. XRD and NH3-TPD showed greater interaction between the W-phase and the Bronsted acid sites in the channels of the zeolite than between Cr-phase and the acid sites in the zeolite.
文摘Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidative coupling of methane （OCM） to higher hydrocarbons at different reaction conditions （viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm^3 ·g^-1·h^-1） have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties （viz. surface area, basicity/base strength distribution） and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity （strong basic sites） and the C2＋ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO （Na/Ca = 0.1, before calcination） catalyst （calcined at 750 ℃）, showed best performance （C2＋ selectivity of 68.8% with 24.7% methane conversion）, whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.
文摘In the current work,molecular dynamics simulation is employed to understand the intrinsic growth of carbon dioxide and methane hydrate starting from a seed crystal of methane and carbon dioxide respectively.This comparison was carried out because it has relevance to the recovery of methane gas from natural gas hydrate reservoirs by simultaneously sequestering a greenhouse gas like CO2.The seed crystal of carbon dioxide and methane hydrate was allowed to grow from a super-saturated mixture of carbon dioxide or methane molecules in water respectively.Two different concentrations(1:6 and 1:8.5)of CO2/CH4 molecules per water molecule were chosen based on gas–water composition in hydrate phase.The molecular level growth as a function of time was investigated by all atomistic molecular dynamics simulation under suitable temperature and pressure range which was well above the hydrate stability zone to ensure significantly faster growth kinetics.The concentration of CO2 molecules in water played a significant role in growth kinetics,and it was observed that maximizing the CO2 concentration in the aqueous phase may not result in faster growth of CO2 hydrate.On the contrary,methane hydrate growth was independent of methane molecule concentration in the aqueous phase.We have validated our results by performing experimental work on carbon dioxide hydrate where it was seen that under conditions appropriate for liquid CO2,the growth for carbon dioxide hydrate was very slow in the beginning.
基金the funding support from The Bioenergy Technologies Office (BETO) within the US DOE’s Office of Energy Efficiency and Renewable Energythe funding support from the American Recovery and Reinvestment Actsupported by the US DOE’s Office of Science, Biological and Environmental Research program through contract DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the U.S. Department of Energy
文摘This scale-up study demonstrated the feasibility of an ionic liquid(IL)pretreatment process at 40 kg scale,using the IL 1-ethyl-3-methylimidazolium acetate([C2C1Im][OAc])as the solvent.The pretreatment was followed by enzymatic hydrolysis through which the process efficiency for biomass conversion to monomeric sugars was determined.The results show that 43 wt%of switchgrass was dissolved in IL after 2 h of pretreatment at 160℃ with 15 wt%solid loading.A 120 h enzymatic hydrolysis of the pretreated switchgrass results in 96%glucan and 98%xylan conversion.[C2C1Im][OAc]pretreatment has been successfully scaled up to 40 kg with improved sugar titers and yields relative to bench scale(6 kg).The mass flow of the overall process was established and the major scale-up challenges of the process were identified.
文摘Natural gas conversion to petrochemicals, principally, benzene, naphthalene, toluene, as well as ethylene under non-oxidative conditions was examined in a fixed bed flow reactor at 700 ℃ and gaseous hourly space velocity （GHSV） of 1500 ml·g ^-1·h^-1 at time-on-stream ranging from 5 rain to 4 h using catalysts containing 6.0%Mo/H-ZSM-5 promoted with Pd or Ir metal. The catalysts were characterized by XRD, TPD, and TGA. The addition of Pd or Ir to 6%Mo/H-ZSM-5 catalyst promoted ethylene production but inhibited the cyclization reaction to aromatics owing to the strong interaction between these noble metals and the framework Al species, which were attached to the acid sites during the impregnation process. Coke deposition on the catalysts was found to decrease upon addition of 0.5wt% of Pd or Ir to 6%Mo/H-ZSM-5 catalyst owing to the hydrogenating activity of these metals.
文摘Alkaline earth metal （Mg,Ca,Sr and Ba）-doped Mo-V-Sb-O x catalysts,prepared by a dry-up method,have been investigated for their catalytic performance in the oxidation of propane under different reaction conditions.The catalysts have been characterized by N2 adsorption-desorption,temperature-programmed desorption （TPD） of NH3,SEM and XRD.Influence of water vapor on the catalytic performance,particularly on the selectivities to acetic acid and acrylic acid,has also been studied.The selectivity to acrylic acid was improved significantly by the doping of alkaline earth metals to Mo-V-Sb-O x catalysts.The surface acidic sites of the catalyst decreased with the doping of the catalyst with alkaline earth metals,which ultimately was found to be beneficial for obtaining high selectivity to acrylic acid.The catalytic activity and product selectivities were found to be influenced by the reaction temperature,C3H8/O2 ratio and space velocity.A significant improvement in the selectivity to acrylic acid has also been observed by the addition of water vapor in the feed of propane and oxygen in the oxidation of propane.
文摘Extended use of supported Pt catalysts causes thermal migration of Pt particles to form large agglomerates,thus decreasing the catalytic activity.The combination of Pt with Re protects Pt against migration.In addition,Cl injection into the reactor assists Pt particles redispersion to prolong catalyst life.In this work,a PtRe/H-ZSM-5 catalyst was treated with either HCl or HF to investigate their role in activating or deactivating the catalyst.The conversion exceeded 90% in the whole temperature range with the PtRe/H-ZSM-5(HCl) catalyst,and its activity for the direct isomerization of cyclohexene to methylcyclopentenes(MCPEs) was the lowest but the activity for the hydrogenation of the MCPEs to methylcyclopentane was the highest.The reactivities of MCPEs and cyclohexadienes on the catalysts were similar because both are dehydrogenation reactions.Benzene production was significantly higher on the hydrochlorinated catalyst than on the other catalysts,and its hydrocracking activity was the lowest,which is a good characteristic for processing catalysts where cracking is undesired.
基金the Nuclear R&D Program by the Korean Ministry of Science and Technology
文摘Oxidation reaction of rare earth chlorides(Ce/Pr/Nd/EuCl3) in a LiCl-KCl eutectic molten salt was carried out using an oxygen sparging method. Regardless of the sparging time and the molten salt temperature, oxychlorides (NdOCl, PrOCl) and oxides(CeO, Eu2O3, PrO2) were formed as a oxidation products(i.e. precipitates) by the reaction with oxygen. The conversion efficiency of the rare earth elements to the precipitates increases with the sparging time and the molten salt temperature. In the conditions of 650 ℃ of a molten salt temperature and 420 min of a sparging time, the values of the conversion efficiency of the used rare earth chlorides were over 99.9%. Information on the hydrodynamics of an oxygen-molten salt two phase flow system is essential since its hydrodynamics strongly affect the oxidation reaction of rare earth elements in an eutectic chloride melts.
文摘In this work, the effects of injecting an evaporating liquid jet into solid-gas flow are experimentally investigated. A new model （SHED model） and a supplementary model （spray model） have also been proposed to investigate some flow-field characteristics in three-phase fluidized bed with the mean relative error 4.3% between model and measured results. Some experiments were conducted to study the influences of flow-field parameters such as liquid volumetric flow rate, injection velocity, jet angle and gas superficial velocity as well as solid mass flux on the jet penetration depth （JPD）. In addition, independent variables were experimentally employed to propose two empirical correlations for JPD by using multiple regression method and spray cone angle （SCA） by using dimensional analysis technique. The mean relative errors between the JPD and SCA correlations versus ex- perimental data were 7.5% and 3.9%, respectively. In addition, in order to identify the variable effect, a parametric study was carried out. Applying the proposed model can avoid direct use of expensive devices to measureJPD and to nredict dronlet size.
文摘In the coal-based combustion and gasification processes, the mineral matter contained in the coal (predominantly oxides), is left as an incombustible residue, termed ash. Commonly, ash deposits are formed on the heat absorbing surfaces of the exposed equipment of the combustion/gasification processes. These deposits lead to the occurrence of slagging or fouling and. consequently, reduced process efficiency. The ash fusion temperatures (AFTs) signify the temperature range over which the ash deposits are formed on the heat absorbing surfaces of the process equipment. Thus, for designing and operating the coal-based processes, it is important to have mathematical models predicting accurately the four types of AFTs namely initial deformation temperature, softening temperature, hemispherical temperature, and flow temperature. Several linear/nonlinear models with varying prediction accuracies and complexities are available for the AFT prediction. Their principal drawback is their applicability to the coals originating from a limited number of geographical regions. Accordingly, this study presents computational intelligenee (CI) based nonlinear models to predict the four AFTs using the oxide composition of the coal ash as the model input. The CI methods used in the modeling are genetic programming (GP), artificial neural networks, and support vector regression. The no table features of this study are that the models with a better AFT prediction and generalization performanee, a wider application potential, and reduced complexity, have been developed. Among the Ci-based models, GP and MLP based models have yielded overall improved performanee in predicting all four AFTs.
