The hysteresis characteristics of catalytic partial oxidation of methane (CPOM) in a Swiss-roll reactor are predicted numerically by varying Damköhler number. Particular attention is paid to the ...influences of heat recirculation, gas hourly space velocity (GHSV), and atomic O/C ratio on the hysteresis loop and performance of CPOM. The reactions of methane combustion, steam reforming, and CO2 or dry reforming are simultaneously considered. The results reveal that preheating reactants through excess enthalpy recovery is conducive to the ignition of CPOM and extending its extinction limit, so the ignition and extinction Damköhler numbers are lowered. The analysis also suggests that steam reforming is more sensitive to the heat recovery than methane combustion and dry reforming. An increase in GHSV reduces the residence time of reactants in the catalyst bed, thereby enlarging the ignition and extinction Damköhler numbers of CPOM. A higher O/C ratio facilitates the ignition of CPOM, stemming from more oxygen supplied, but the ratio should be controlled below 1.2. From the hysteresis phenomena, hydrogen can be produced from methane at a lower Damköhler number to save more energy for performing CPOM.
•Hysteresis characteristics of catalytic partial oxidation of methane are studied•A Swiss-roll reactor is adopted.•Methane combustion, steam reforming, and dry reforming are considered.•Preheating reactants facilitates extending the extinction limit of CPOM.•Energy for hydrogen production can be saved via hysteresis phenomena
The effect of heat recovery on hydrogen production from catalytic partial oxidation of methane (CPOM) and its reaction characteristics in a reactor are investigated using numerical simulations. The ...reactor is featured by a Swiss-roll structure in which a rhodium (Rh) catalyst bed is embedded at the center of the reactor. By recovering the waste heat from the product gas to preheat the reactants, it is found that the combustion, steam reforming and dry reforming of methane in the catalyst bed are enhanced to a great extent. As a result, the methane conversion and hydrogen yield are improved more than 10%. Considering the operation conditions, a high performance of hydrogen production from CPOM can be achieved if the number of turns in the reactor is increased or the gas hourly space velocity (GHSV) of the reactants in the catalyst bed is lower. However, with the condition of heat recovery, the flow direction of the reactants in the reactor almost plays no part in affecting the performance of CPOM. In summary, the predictions reveal that the reactor with a Swiss-roll structure can be applied for implementing CPOM with high yield of hydrogen.
Sprays are an important tool for removing air pollutants through absorption. To recognize the mass transport characteristics of air pollutants in sprays, four different air pollutants of sulfur ...dioxide (SO2), hydrogen chloride (HCl), ammonia (NH3), and nitric acid (HNO3) absorbed by droplets in sprays are analyzed theoretically in association with a numerical method. The number density of droplet in a spray is in the range of 103–106cm−3 and the droplet radius is 30μm. By conceiving a bubble as the sphere of influence of droplet–droplet interaction, the predictions indicate that the mass diffusion number and the number density are two important factors in determining the absorption process and results. When the mass diffusion number is larger, the radius of scavenging wave is increased and the effect of the droplet mutual interaction is thus intensified. An increase in number density facilitates the mass transfer of air pollutants from the gas phase to the liquid phase. However, the uptake amount of solutes by individual droplets is abated. At last, according to the mass distributions of the solutes in the liquid (droplet) phase, the appropriate number densities in sprays for the absorption of the four air pollutants are suggested.
► SO2, HCl, NH3, and HNO3 absorbed by droplets in sprays are analyzed theoretically. ► The number density of a droplet in a spray is in the range of 103–106cm−3. ► A bubble is conceived as the sphere of influence of the droplet–droplet interaction. ► Mass diffusion number and the number density are two important factors in absorption. ► Appropriate number densities for the absorption of the four air pollutants are suggested.
Chemical reaction characteristics of a water gas shift reaction (WGSR) heated by microwaves are investigated experimentally where a Cu–Zn-based catalyst is employed. The experiments indicate that the ...performance of the low-temperature shift reaction (LTSR) increases with increasing temperature and steam/CO molar ratio. The effect of increasing temperature on CO conversion with microwave heating is contrary to that with conventional heating where the thermodynamic equilibrium dominates the LTSR in the latter. It follows that the reactions of the LTSR with microwave heating are governed by chemical kinetics. To further figure out the reaction phenomena inside the catalyst bed with microwave irradiation, a new chemical kinetic model accounting for the behavior of the LTSR are developed and the reaction phenomena are simulated numerically. In the numerical method, the continuity, momentum, energy and species equations as well as the electromagnetic fields are simultaneously solved. It is of interest that the temperature distribution in the catalyst bed is nearly uniform due to the exothermic reaction featured. When the thermal behavior of the LTSR is examined, heat generation stemming from microwave irradiation is always larger than that from the chemical reaction.
► Low-temperature shift reaction (LTSR) heated by microwaves is investigated experimentally. ► The reactions of the LTSR with microwave heating are governed by chemical kinetics. ► A new chemical kinetic model accounting for the behavior of the LTSR are conducted. ► LTSR is also studied numerically. ► Heat generation due to microwave irradiation is larger than from chemical reaction.
The thoroughness of hand hygiene (HH) was evaluated using a simulation method in which health care workers (HCWs) rubbed their hands with a fluorescent substance, washed with water, and placed their ...hands under an ultraviolet detector to identify areas missed. Most residue points were located in the tips of the nails (38.6%), followed by fingertips (17.4%). This stress-free “seeing is believing” program can encourage HCWs' active participation in sustaining the HH culture of health care institutions.
Catalytic partial oxidation of methane (CPOM) is a promising method for hydrogen production with autothermal reaction. To figure out the unsteady reaction characteristics of CPOM in a Swiss-roll ...reactor along with heat recirculation, a numerical method is employed to simulate the transient reaction dynamics, with emphasis on energy recovery using exergy analysis. Three different gas hourly space velocities (GHSVs) of 5000, 10,000 and 50,000h−1 with the condition of atomic O/C ratio of 1 are considered. The predictions indicate that increasing GHSV substantially shortens the transient period of chemical reactions; however, it also reduces the methane conversion, as results of more reactants sent into the reactor and shorter residence time of the reactants in the catalyst bed. Within the investigated range of GHSV, the methane conversion with energy recovery at the steady state is larger than 80%, much higher than the reaction without heat recovery. The selectivities of H2 and CO in the product gas are always larger than 90%. The exergy recovery is in the range of 66–80%, implying that over two-third useful work contained in the product gas can be reused to preheat the reactants in the reactor, thereby enhancing the performance of CPOM.
► A numerical method is employed to simulate the catalytic partial oxidation of methane. ► Increasing GHSV substantially shortens the transient period of chemical reactions. ► The methane conversion with energy recovery at the steady state is larger than 80%. ► The selectivities of H2 and CO in the product gas are always larger than 90%. ► For GHSV between 5000 and 50,000h−1, the exergy recovery is in the range of 66–80%.
The study of high-throughput genomic profiles from a pharmacogenomics viewpoint has provided unprecedented insights into the oncogenic features modulating drug response. A recent study screened for ...the response of a thousand human cancer cell lines to a wide collection of anti-cancer drugs and illuminated the link between cellular genotypes and vulnerability. However, due to essential differences between cell lines and tumors, to date the translation into predicting drug response in tumors remains challenging. Recently, advances in deep learning have revolutionized bioinformatics and introduced new techniques to the integration of genomic data. Its application on pharmacogenomics may fill the gap between genomics and drug response and improve the prediction of drug response in tumors.
We proposed a deep learning model to predict drug response (DeepDR) based on mutation and expression profiles of a cancer cell or a tumor. The model contains three deep neural networks (DNNs), i) a mutation encoder pre-trained using a large pan-cancer dataset (The Cancer Genome Atlas; TCGA) to abstract core representations of high-dimension mutation data, ii) a pre-trained expression encoder, and iii) a drug response predictor network integrating the first two subnetworks. Given a pair of mutation and expression profiles, the model predicts IC
values of 265 drugs. We trained and tested the model on a dataset of 622 cancer cell lines and achieved an overall prediction performance of mean squared error at 1.96 (log-scale IC
values). The performance was superior in prediction error or stability than two classical methods (linear regression and support vector machine) and four analog DNN models of DeepDR, including DNNs built without TCGA pre-training, partly replaced by principal components, and built on individual types of input data. We then applied the model to predict drug response of 9059 tumors of 33 cancer types. Using per-cancer and pan-cancer settings, the model predicted both known, including EGFR inhibitors in non-small cell lung cancer and tamoxifen in ER+ breast cancer, and novel drug targets, such as vinorelbine for TTN-mutated tumors. The comprehensive analysis further revealed the molecular mechanisms underlying the resistance to a chemotherapeutic drug docetaxel in a pan-cancer setting and the anti-cancer potential of a novel agent, CX-5461, in treating gliomas and hematopoietic malignancies.
Here we present, as far as we know, the first DNN model to translate pharmacogenomics features identified from in vitro drug screening to predict the response of tumors. The results covered both well-studied and novel mechanisms of drug resistance and drug targets. Our model and findings improve the prediction of drug response and the identification of novel therapeutic options.
Background “Patient empowerment” is an important component of World Health Organization hand hygiene program, but little is known about the intentions and attitude of patients/families and health ...care workers (HCWs) regarding this. Methods A cross-sectional survey using questionnaires was conducted in a tertiary teaching hospital in Taiwan to assess hand hygiene knowledge and the attitudes and intentions regarding patient empowerment among patients/families and HCWs. Results Among patients/families, 95.4% (329/345) had positive attitudes regarding patient empowerment; however, only 67.2% (232/345) had the positive intention to remind HCWs about hand hygiene ( P < .001). Risk factors for negative intention were being female (odds ratio OR, 1.82; 95% confidence interval CI: 1.08-3.03), illiteracy (OR, 3.18; 95% CI: 0.86-11.7), and being patients/families in the pediatric department (OR, 1.86; 95% CI: 0.93-3.64). Among HCWs, the difference between positive attitude (81.1%; 714/880) and positive intention regarding being reminded about hand hygiene (62.8%; 553/880) was significant ( P < .001). Risk factors for negative intention were age > 25 years (OR, 3.20; 95% CI: 1.51-6.81) and a negative attitude toward patient empowerment (OR, 10.00; 95% CI: 5.88-16.67). Conclusion There were significant gaps between attitude and intention regarding patient empowerment both among patients/families and HCWs. Special strategies targeting women, the pediatric population, or illiterate people may help improve patient/family participation. Additionally, hand hygiene education should be incorporated into early-stage medical/nursing education to create a facilitating environment. Patients/families and HCWs cooperation is needed to promote the hand hygiene program further.
Hysteresis loops of catalytic partial oxidation of methane (CPOM) for hydrogen production under the effects of varied Reynolds number and Damköhler number are investigated numerically in this study. ...The physical phenomena are predicted using the indirect mechanism, which consists of the total oxidation (or combustion), steam reforming and CO
2 reforming of methane in a catalyst bed. Numerical results reveal that, when the Damköhler number is relatively low, a hysteresis loop of CPOM from varying Reynolds number develops. Increasing the Damköhler number leads to the loop shifting toward the regime of high Reynolds number. However, once the Damköhler number is large to a certain extent, the chemical reactions are always exhibited for the Reynolds number less than 2000. A closed loop is thus not observed. Alternatively, for a given Reynolds number, an ignited Damköhler number and an extinguished Damköhler number can be obtained. Accordingly, three different regions in the plot of Damköhler number versus Reynolds number are identified. Physically, when the role played by Damköhler number on CPOM is much more important than by the Reynolds number (Region I), the thermal effect governs the chemical reactions. In contrast, if the Reynolds number plays a key role in determining the CPOM (Region III), the chemically frozen flow prevails over the catalyst bed. When the residence times of the total oxidation and convection in the catalyst bed are in an equivalent state (Region II), CPOM is characterized by a dual-solution, rendering the hysteresis loops. From the distributions of ignited and extinguished Damköhler numbers, the catalytic reactor and operation of partial oxidation of methane and other fuels can be designed accordingly.
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