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A redox process combining propane dehydrogenation (PDH) with selective hydrogen combustion (SHC) is proposed, modeled, simulated, and optimized. In this process, PDH and SHC catalysts are physically mixed in a fixed-bed reactor, so that the two reactions proceed simultaneously. The redox process can be up to 177.0% higher in propylene yield than the conventional process where only PDH catalysts are packed in the reactor. The reason is twofold: firstly, SHC reaction consumes hydrogen and then shifts PDH reaction equilibrium towards propylene; secondly, SHC reaction provides much heat to drive the highly endothermic PDH reaction. Considering propylene yield, operating time, and other factors, the preferable operating conditions for the redox process are a feed temperature of 973 K, a feed pressure of 1 bar, and a mole ratio of H2 to C3H8 of 0.15, and the optimal mass fraction of PDH catalyst is 0.5. This work should provide some useful guidance for the development of redox processes for propane dehydrogenation.

This study aimed to explore the structure and antibacterial properties of chitooligosaccharide monomers with different polymerization degrees and to provide a theoretical basis for inhibiting Salmonella infection. Chitosan was used as a raw material to prepare and separate low-molecular-weight chitooligosaccharides. Chitobiose, chitotriose, and chitotetraose were obtained by gradient elution with cation exchange resin. The molecular weights and acetyl groups of the three monomers were determined by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and nuclear magnetic resonance (NMR), respectively. Three chitooligosaccharide monomers were used to explore the antibacterial effect on Salmonella. The results showed that the degree of deacetylation of chitosan was 92.6%, and the enzyme activity of chitosanase was 102.53 U/g. Within 18 h, chitosan was enzymatically hydrolyzed to chitooligosaccharides containing chitobiose, chitotriose, and chitotetraose, which were analyzed by thin-layer chromatography (TLC) and MALDI-TOF. MALD-TOF and TLC showed that the separation of monomers with ion exchange resins was effective, and NMR showed that there was no acetyl group. Chitobiose had a poor inhibitory effect on Salmonella, and chitotriose and chitotetraose had equivalent antibacterial effects.

Bimetallic catalyst screening for ester selective hydrogenation has been performed by combining microkinetic analysis and machine learning methods.

Oxychlorination regeneration is an important and effective regeneration method for Pt based catalysts for propane dehydrogenation.

By using a descriptor-based microkinetic analysis combined with results from density functional theory calculations over eight transition-metal (including Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) terrace and stepped surfaces, intermetallic compounds have been screened to search for inexpensive and environmentally friendly propane dehydrogenation (PDH) catalysts with enhanced catalytic performance. Based on the scaling relations, the formation energies of ethyl on terrace and methylidyne on stepped surfaces are identified as two descriptors to represent the energetics of other reaction intermediates and transition sates. The derived PDH activity and propylene selectivity volcano curves not only provide a rational interpretation of the previously experimentally reported catalyst candidates, but also predict several unexpected binary combinations by screening 1482 A3B1 and 741 A1B1 intermetallic compounds. The non-precious Fe3Ga1 is then synthesized and evaluated. Its improved propylene selectivity and catalytic stability with respect to those of the Pt catalyst validates the theoretical predictions experimentally.

The cisterna magna has been defined as the space between the inferior margin of the cerebellar vermis to the level of the foramen magnum, while an enlarged dorsal subarachnoid space at the occipito-cervical junction extending from the foramen magnum to the upper border of the axis (C2) is still ignored. Recently, the myodural bridge complex is proved to drive the cerebral spinal fluid flowing via this region, we therefore introduce the “occipito-atlantal cistern (OAC)” to better describe the subarachnoid space and provide a detailed rationale. The present study utilized several methods, including MRI, gross anatomical dissection, P45 sheet plastination, and three-dimensional visualization. OAC was observed to be an enlarge subarachnoid space, extending from the foramen magnum to the level of the C2. In the median sagittal plane, OAC was a funnel shape and its anteroposterior dimensions were 15.92 ± 4.20 mm at the level of the C0, 4.49 ± 1.25 mm at the level of the posterior arch of the C1, and 2.88 ± 0.77mm at the level of the arch of the C2, respectively. In the median sagittal plane, the spino-dural angle of the OAC was calculated to be 35.10 ± 6.91 degrees, and the area of OAC was calculated to be 232.28 ± 71.02 mm2. The present study provides OAC is a subarachnoid space independent from the cisterna magna. Because of its distinctive anatomy, as well as theoretical and clinical significance, OAC deserves its own name.

Melanoidins, the brown late-stage Maillard reaction products, are responsible for color development and refractoriness in thermal hydrolyzed sludge (THS), causing negative effects on wastewater treatment. This study aimed to develop a methodology for the identification, isolation and preliminary characterization of the THS melanoidins. After thermal hydrolysis, the formation of melanoidins were confirmed by physicochemical indicators and excitation-emission matrix fluorescence analysis. The macroporous resin adsorption method was adopted to successfully extract melanoidins from THS with high recovery and selectivity. The main chemical components of the extracted melanoidins were carbohydrate (23.1 %), protein (43.8 %) and phenol (13.7 %), and the C/N was 4.5. In addition, furans, alcohols and sulfur-containing volatile substances were detected by pyrolysis-gas chromatography-mass spectrometry. Fourier transform infrared spectroscopy determined that functional groups such as CO, CN, NH, C-O-C, amide I and phenyl were present in the structure of THS melanoidins, and nuclear magnetic resonance spectroscopy indicated the formation of heterocyclic macromolecular structures. Their formation pathways were speculated to involve the cross-linkage of low-molecular-weight components (e.g. proteins, Amadori and Schiff base compounds) and the polymerization of heterocyclic units (e.g. furans, pyroles and pyrazines). The above results clarify the fundamental characteristics of the melanoidins formed during sludge thermal hydrolysis and will help improve subsequent research on melanoidins control.

An experimental investigation and dynamic simulation of vertical falling-film LiBr/H2O absorption heat transformer systems have been reported in this paper. The established 20 kW experimental equipment was used to test the dynamic performance and verified the mathematical model. The experimental results show that there is a time delay between the input heat and output useful heat, and the time delay of the experimental results is 115 s. The simulated results show that the response time increases with increasing total solution mass and increases with decreasing solution mass flow rate. The temperature flow oscillations decrease with increasing total solution mass and decrease when the solution mass flow rate decreases. The response time of the absorption heat transformer is almost linearly related to the characteristic time of solution storage, which provides guidance for the operation and prediction. By adjusting the total solution mass and solution mass flow rate, theoretically the response time can be reduced to approximately 150 s. The temperature change range of the absorber outlet water can be controlled within 0.5 K by reducing the solution mass flow rate. The total solution mass and mass flow rate should be reduced, which can reduce temperature flow oscillations and shorten the time delay. The response time can be predicted by combining the experimental data and the linear relationship of the response time for any absorption heat transformer.

Numerous studies investigating an association between the matrix metalloproteinase-1 (MMP-1) gene rs1799750 polymorphism and breast cancer (BC) risk have reported inconsistent results. Therefore, this meta-analysis was undertaken to obtain a more precise estimate of the possible association between this genetic locus and BC susceptibility. Methods: Eight eligible studies involving 3439 cases and 3517 controls were identified by searching the PubMed, Google, CNKI, and EMBASE databases systematically through October 1, 2020. Results: The MMP-1 rs1799750 polymorphism was associated with a reduced BC risk in the overall study population under the heterozygous model. Stratification analyses indicated that this association is strong in Asians. Conclusion: There is evidence of an association between the MMP-1 rs1799750 polymorphism and BC susceptibility, viewed as a decreased risk factor for BC. More extensive studies with more diverse ethnic populations are necessary to confirm these findings.

The basic premise of anammox-technical application reliability in municipal wastewater treatment is substantially enriched anammox bacteria. To enrich the anammox, the special interaction mechanism between the suspended sludge (SS) and anoxic biofilm was investigated over three months in a partial denitrification/anammox biosystem subjected to dynamic changes in SS (absence→ presence→ absence). Results show that the introduction of SS significantly decreased the anammox nitrogen removal efficiency (83.8 ± 6.5%→ 48.7 ± 17.0%). With the presence or absence of SS, the spatial distribution of anammox bacteria within the anoxic biofilm gradually changed between the inner and outer layers, as detected by CLSM-FISH. qPCR and metagenomic sequencing show that changes in the presence and absence status of SS significantly reduced the abundance of the NO reducing functional gene, while the NO supply capacity (NO

Vanadium-oxide-based catalysts have recently been found very promising for the catalytic dehydrogenation of propane. In this work, self-consistent density functional theory calculations have been performed to examine how the electronic structure of the V2O3(0001) surface is modified by single-atom doping and how the catalytic properties can be tailored to propane dehydrogenation. The structural stability of single-atom-doped V2O3(0001) surfaces is assessed by comparing the adsorption energies of single atoms with the cohesive energies of bulk metals. A weak Lewis acid-base interaction is found to occur on the pristine surface, which can be strengthened and weakened by substitution of single atoms for V and O, respectively. On these two types of oxide surfaces, single atoms act as promoters and active sites. The first dehydrogenation step is identified as the rate-limiting step by microkinetic analysis. On all the single-atom-doped surfaces, the activation energy for water formation is higher than that for hydrogen recombination, implying that reduction of the oxide surfaces is difficult to take place during the course of the reaction. If a compromise between the catalytic activity and catalyst selectivity is made, Mn1-V2O3 is suggested to be a good candidate as the catalyst for propane dehydrogenation.

Volcano curves have proven to be particularly useful in new catalyst design in the field of heterogeneous catalysis. On the other hand, the further enhancement of the performance of the optimal cat...

In this study, the support effects on the Pd-catalyzed semi-hydrogenation of acetylene have been investigated from the structural and kinetic perspectives. According to the results of kinetic analysis and X-ray photoelectron spectroscopy, hydrogen temperature-programmed reduction, temperature-programmed hydride decomposition, and in situ X-ray diffraction measurements, using carbon nanotubes as support for Pd nanocatalysts with various sizes instead of α-Al2O3 decreases the Pd0 3d binding energy and suppresses the formation of undesirable palladium hydride species, thus increasing the ethylene yield. Furthermore, X-ray absorption spectroscopy, high-resolution transmission electron microscopy, and C2H4 temperature-programmed desorption studies combined with density-functional theory calculations reveal the existence of a unique Pd local environment, containing subsurface carbon atoms, that produces positive geometric effects on the acetylene conversion reaction. Therefore, tailoring the Pd local environment and electronic properties represents an effective strategy for the fabrication and design of highly active and selective Pd semi-hydrogenation catalysts.

An experimentally obtained volcano-type curve is observed for propane dehydrogenation over a group of atomically dispersed Pt catalysts on various supports. The oxidation state of Ptδ+ active sites plays a determining role in enhancing the activity.

The kinetics of dimethyl oxalate (DMO) hydrogenation over Cu(111) and Cu2O(111) has been studied to understand the role of Cu0 and Cu+ sites in ethyl glycol (EG) production over Cu-based catalysts ...

The catalytic dehydrogenation of light alkanes over Pt catalysts is generally accepted to follow a reverse Horiuti–Polanyi mechanism. Using a microkinetic analysis in combination with results from ...

The structure–performance relationship is a critical fundamental issue in heterogeneous catalysis, and the size-dependent structure sensitivity of catalytic reactions has long been researched in ca...

Traditional condensing air-conditioning systems consume large amounts of energy in hot and humid areas, and it is difficult to achieve simultaneous control of temperature and humidity. A combined absorption refrigeration (AR) and liquid desiccant dehumidification (LDD) air-conditioning system based on cascade utilization of low-grade heat source is proposed. The system can realize independent control of temperature and humidity and carry out profound recovery of low-grade heat sources. Under the design conditions, the heat utilization rate ζ reaches 21.05%, which is 2.73 times that of the conventional absorption refrigeration reference system. A parametric sensitivity analysis is performed to optimize the system. The ζ increases from 9.79% to 18.55% and the coefficient of performance COPt increases from 0.33 to 0.35 with an increase in chilled water temperature from 7°C to 15°C. With an increase in regenerant solution temperature from 60°C to 70°C, the ζ achieves the optimal value of 21.05% at 68°C. ζ decreases from 21.05% to 15.05% as the concentration of the regenerant solution increases from 36% to 40%. Under variable environmental temperature and humidity, the ζ of the proposed system changes within a small range and stays much higher than that of the reference system with the same quality heat source, which indicates that the proposed system has a better adaptability to changing environmental parameters.

Atomic regulation of metal catalysts has emerged as an intriguing yet challenging strategy to boost product selectivity. Here, we report a density functional theory-guided atomic design strategy for the fabrication of a NiGa intermetallic catalyst with completely isolated Ni sites to optimize acetylene semi-hydrogenation processes. Such Ni sites show not only preferential acetylene π-adsorption, but also enhanced ethylene desorption. The characteristics of the Ni sites are confirmed by multiple characterization techniques, including aberration-corrected high-resolution scanning transmission electron microscopy and X-ray absorption spectrometry measurements. The superior performance is also confirmed experimentally against a Ni5 Ga3 intermetallic catalyst with partially isolated Ni sites and against a Ni catalyst with multi-atomic ensemble Ni sites. Accordingly, the NiGa intermetallic catalyst with the completely isolated Ni sites shows significantly enhanced selectivity to ethylene and suppressed coke formation.

In order to deal with the problems of poor anti-interference, low reconstruction clarity and large errors in the traditional medical image reconstruction methods, we proposed a fuzzy medical images three-dimensional (3D) reconstruction method using quantum algorithm. First of all, a feature matching model of fuzzy medical image was built. Secondly, this study decomposed the edge contour features by using the Gaussian mixture feature matching method, extracted the edge contour vectors of fuzzy medical image, and enhanced the information of fuzzy medical images by adopting the region edge sharpening. Thirdly, this study reorganized the 3D texture structure of images and reconstructed the sparse scattered points according to its texture and detail regions. Finally, we combined with the gray histogram of fuzzy medical images to achieve the adaptive pixel reconstruction of fuzzy medical images, and completed the 3D reconstruction of fuzzy medical images by employing the quantum algorithm. The results show that the proposed method is characterized by high matching degree of image features and balanced distribution of point clouds, and the self-similarity coefficient of the reconstructed texture can reach 0.994; in addition, the SINR value of the reconstruction result can be maintained around 100dB, and it has lower error rate than the traditional method, thereby improving the detection and recognition capability of medical images, and the algorithm has certain practical application.

We have previously reported that flavonoid extract from propolis (FP) can improve cardiac function in rats following myocardial infarction (MI). However, the mechanisms responsible for the cardioprotective effects of FP have not been fully elucidated. In the current study, we explored whether FP can reduce inflammatory cytokines and attenuate sympathetic nerve system activity and antiendoplasmic reticulum (ER) stress and whether the cardioprotective effects are related to peroxisome proliferator-activated receptor gamma (PPAR-γ) activation. Sprague Dawley rats were randomly divided into six groups: Sham group received the surgical procedure but no artery was ligated; MI group received ligation of the left anterior descending (LAD) branch of the coronary artery; MI + FP group received FP (12.5 mg/kg/d, intragastrically) seven days prior to LAD ligation; FP group (Sham group + 12.5 mg/kg/d, intragastrically); MI + FP + GW9662 group received FP prior to LAD ligation with the addition of a specific PPAR-γ inhibitor (GW9662), 1 mg/kg/d, orally); and MI + GW9662 group received the PPAR-γ inhibitor and LAD ligation. The results demonstrated that the following inflammatory markers were significantly elevated following MI as compared with expression in sham animals: IL-1β, TNF-α, CRP; markers of sympathetic activation: plasma norepinephrine, epinephrine and GAP43, nerve growth factor, thyroid hormone; and ER stress response markers GRP78 and CHOP. Notably, the above changes were attenuated by FP, and GW9662 was able to alleviate the effect of FP. In conclusion, FP induces a cardioprotective effect following myocardial infarction by activating PPAR-γ, leading to less inflammation, cardiac sympathetic activity, and ER stress.