Fischer-Tropsch synthesis to olefins boosted by MFI zeolite nanosheets.

Catalytic reactions are severely restricted by the strong adsorption of product molecules on the catalyst surface, where promoting desorption of the product and hindering its re-adsorption benefit the formation of free sites on the catalyst surface for continuous substrate conversion1,2. A solution to this issue is constructing a robust nanochannel for the rapid escape of products. We demonstrate here that MFI zeolite crystals with a short b-axis of 90-110 nm and a finely controllable microporous environment can effectively boost the Fischer-Tropsch synthesis to olefins by shipping the olefin molecules. The ferric carbide catalyst (Na-FeCx) physically mixed with a zeolite promoter exhibited a CO conversion of 82.5% with an olefin selectivity of 72.0% at the low temperature of 260 °C. By contrast, Na-FeCx alone without the zeolite promoter is poorly active under equivalent conditions, and shows the significantly improved olefin productivity achieved through the zeolite promoter. These results show that the well-designed zeolite, as a promising promoter, significantly boosts Fischer-Tropsch synthesis to olefins by accelerating escape of the product from the catalyst surface.

The effect of transcutaneous electrical nerve stimulation (TENS) on pain control and phenylethanolamine-N-methyltransferase (PNMT) gene expression after cesarean section.

Transcutaneous electrical nerve stimulation (TENS) is one of the non-pharmacological methods of pain relief that has been able to reduce pain by 70 to 90% in postoperative pain control. This study aimed to determine the effect of TENS on pain control after cesarean section and its effect on PNMT gene expression. For this purpose, a double-blind randomized clinical trial was performed on 70 Chinese patients with elective cesarean section. Patients were divided into case and control groups. In the case group, TENS and analgesic drugs were used to relieve pain, and in the control group, the only analgesic drug was used. Then the severity of pain, recurrence of pain attacks, the number of analgesic drugs used and the amount of analgesic drug used in the first 24 hours after surgery were evaluated and compared. Blood samples were also taken from patients to evaluate PNMT gene expression. The semi-quantitative RT-PCR was used to study changes in gene expression. The results showed that the group treated with TENS had less pain intensity and less recurrence of pain attacks than the group that received only analgesic medication. Also, the frequency of analgesic drug use and its dose in the TENS group were significantly lower than in the control group. TENS, on the other hand, has been able to greatly reduce the expression of the PNMT gene, which is produced during times of stress. Therefore, it is recommended that TENS be used as a non-invasive and non-pharmacological adjuvant effective in reducing pain after cesarean section.

Modeling and Control of COVID-19 Transmission from a Perspective of Polymerization Reaction Dynamics.

Due to the serious economic losses and deaths caused by COVID-19, the modeling and control of such a pandemic has become a hot research topic. This paper finds an analogy between a polymerization reaction and COVID-19 transmission dynamics, which will provide a novel perspective to optimal control measures. Susceptible individuals, exposed people, infected cases, recovered population, and the dead can be assumed to be specific molecules in the polymerization system. In this paper, a hypothetical polymerization reactor is constructed to describe the transmission of an epidemic, and its kinetic parameters are regressed by the least-squares method. The intensity of social distancing u is considered to the mixing degree of the reaction system, and contact tracing and isolation ρ can be regarded as an external circulation in the main reactor to reduce the concentration of active species. Through these analogies, this model can predict the peak infection, deaths, and end time of the epidemic under different control measures to support the decision-making process. Without any measures (u = 1.0 and ρ = 0), more than 90% of the population would be infected. It takes several years to complete herd immunity by nonpharmacological intervention when the proportion of deaths is limited to less than 5%. However, vaccination can reduce the time to tens to hundreds of days, which is related to the maximum number of vaccines per day.

[Establishment of subseries cell lines from tongue cancer single cell and detection of cancer stem cell markers].

OBJECTIVE: To establish subseries cell lines from single, cancer cell of Tca8113M1 cell line and detect the cancer stem cell markers in the different subseries cell lines. METHODS: The subseries cell lines from single cancer cell of Tca8113M1 cell line were established by limiting dilution assay in vitro. The characteristic of tumorigenicity and CD44, CD184, extracellular soluble antigen (ESA) of the cancer stem cell markers were detected by xenotransplantation and flow cytometry respectively. RESULTS: Total 192 single cells of Tca8113M1 cell line were cultured and were deposited as one cell per well. There were 12 subpopulations origin from 192 single cells spheroid cultures. The ratio was 6.25% (12/192). In the different subpopulations, the tumorigenicity and expression of CD44 and ESA were at high levels, but the expression of CD184 was in different level. There were three kinds morphology of colonies derived from single cancer cells, holoclone, meroclone and paraclone. Cell line could be derived from carcinoma cell holoclones by cell culture. Meroclone and paraclone did not exist in cell culture in vitro. CONCLUSION: Tongue cancer stem cell may exist in Tca8113M1 cell line, cell line can be established and holoclone is the origin of cell line. This is a novel approach to the identification and enrichment for cancer stem cell.

[Measurement of properties of polypropylene copolymers by Raman spectrum].

Fourier-transform (FT) Raman spectra were measured for 7 kinds of different polypropylene copolymers and the assignments of all Raman bands were made through a detailed analysis. Ultimately, by choosing 2 700-3 100 cm(-1) as the characteristic spectral, partial least squares (PLS) regression models were set up for xylene solubles content, ethylene content and ethylene content of xylene solubles in polypropylene copolymers. The values of correlation coefficient (r) between predicted results and actual values were all greater than 0.94, and the values of average relative error (ARE) were all less than 5%. The second PLS factor was also analyzed in this paper, and it was concluded that the original information of the sample was accurately extracted by using PLS regression. This paper offered a kind of possibility for on-line measurement of xylene solubles content, ethylene content and ethylene content of xylene solubles in polypropylene copolymers.

[Quantitative determination of PVC concentration by Raman spectrum].

Quantitative determination of polyvinyl chloride (PVC) concentration by Raman spectrum was studied in the present work. According to partial least squares (PLS) analysis, it was found that scores of PLS factor 1 were proportional to the concentrations of the sample solutions. Meanwhile, the loadings of factor 1 could reflect the contents of PVC and cyclohexanone simultaneously. The PLS regression model for PVC concentration prediction was built. The values of r and root mean square error (RMSE) between predictive results and actual values were 0.9963 and 2.775, respectively. The Raman characteristic peaks of PVC and cyclohexanone were found, including the C-Cl bond for PVC (620 and 695 cm(-1)) and the alicyclic ketone for cyclohexanone (1709 cm(-1)). By using internal standard method, another model for PVC concentration prediction was established, and the values of r and RMSE were 0.9941 and 3.151, respectively. The results indicated that it is feasible to use Raman spectrum to detect the PVC concentration, which is of significant importance to PVC recycling.

[Measurement of ethylene content in polypropylene by Raman spectrum].

Ethylene content in polypropylene was studied by Raman spectrum, combined with partial least squares (PLS) method. The comparison between Raman spectra for polyethylene and polypropylene was carried out, and the spectra between 50 and 600, 600 and 1600, and 2700 and 3100 cm(-1) were analyzed respectively. The models for ethylene content prediction were built, while the model based on 50-3600 cm(-1) spectra gave the best performance. The experiment indicated that Raman spectrum gave the similar predictive results as the near infrared (NIR) spectrum; the values of correlation coefficient (r), relative average deviation (RAD) and root mean square error (RMSE) between predictive results and actual values were 0.995, 2.65% and 0.319, respectively. According to PLS analysis, the loadings of factor 1 could reflect the relationship between the composition of polypropylene molecular chain and ethylene content, and ethylene content had a positive correlation with CH2 content, but a negative correlation with content of CH3, C-H, and C-C. The results indicated that it was feasible to detect the ethylene content in polypropylene by Raman spectrum.

Intensification of adsorption process by using the pyrolytic char from waste tires to remove chromium (VI) from wastewater.

Pyrolysis has the potential of transforming waste into valuable recyclable products. Pyrolytic char (PC) is one of the most important products from the pyrolysis of used tires. One of the most significant applications for pyrolytic char recovered is used for the removal of Cr(VI) in the wastewater effluent to control waste by waste. The surface chemistry properties of surface element distribution/concentration and chemical structure were examined for the pyrolytic char and the commercial activated carbon (CAC) respectively. The results showed that surfaces of PC possesses a large amount of ester and hydrocarbon graft, whereas there are mainly carbon functional components of C-OH, C=O and COOH on the surface of CAC. Therefore the surface electronegativity of PC is lower than that of CAC in the water. The repulsive interactions between the surfaces of PC and the negatively charged Cr(VI) ion are weaker than that of CAC, which results in an intensification of the adsorption process by the utilization of PC. The adsorption isotherms of Cr(VI) ion on the two kinds of carbons were determined experimentally. The larger adsorption amount on the PC in the case of Cr(VI) may be attributed mainly to its special surface micro-chemical environment. The mechanism of the removal Cr(VI) from aqueous solution was assumed to be the integration of adsorption and redox reaction. The adsorption was the rate-controlled step for Cr(VI) removal. The adsorption of Cr(VI) was identified as pseudo-second-order kinetics. The rate constants of adsorption were evaluated.