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[Display omitted] • Pressure resistant, sublethal injury and viable but non-culturable cells existed during the HPP treatment. • The pressure resistant property of different species was positively correlated with the sublethal injury cell count. • The pressure resistant property of different species was negatively correlated with the VBNC cell count. • The combination of HPP with CO 2 or Nisin could reduce the formation of pressure resistant, sublethal injury and VBNC cells. This study aimed to analyze and reduce the pressure resistance (PR), sublethal injury (SLI), and viable but non-culturable (VBNC) populations during HPP. Escherichia coli , Staphylococcus aureus , Bacillus amyloliquefaciens and Lactiplantibacillus plantarum were selected for evaluation of PR, SLI and VBNC cell counts and proportions during HPP. The results revealed that the bactericidal efficiency against these strains gradually improved as the processing pressure increased. However, viable bacteria could still be detected, suggesting that there may involve the presence of resistant population that difficult to be killed or revived from SLI. Further detecting the quantity and proportion of PR, SLI and VBNC bacteria found that these state of cells were present during whole HPP treatment. Additionally, the more resistant a bacterial species was to high pressure, the fewer SLI and more resuscitable VBNC (RVBNC) populations it generated, and vice versa. Therefore, correlation analysis was also employed to make the relationship between log reduction, SLI and RVBNC population ratios clearer. The results demonstrated that the log reduction was highly positive correlation with SLI population ratios, and negative correlation with RVBNC population within our detected species at 500 MPa. Furthermore, CO 2 and Nisin were employed to combined with HPP to reduce these survivors. Comparing with 233, 218, 241 and 259 MPa for HPP treatment, it took 37, 89, 135 and 229 MPa for HPP + CO 2 , and 189, 161, 199 and 292 MPa for HPP + Nisin to the first decimal reduction for E. coli , S.aureus , B. amyloliquefaciens and L. plantarum , respectively. The results indicated that HPP combined with CO 2 or Nisin could significantly reduce the quantity of PR, SLI, and RVBNC cells during HPP, and provide better bactericidal effects. In conclusion, we quantified the presence of PR, SLI, and VBNC bacteria after high pressure treatment and investigate the effectiveness of HPP combined with CO 2 or Nisin to enhance the inactivation of bacteria and reduce the occurrence of PR, SLI, and RVBNC bacteria. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heat, acidity and long-term cultivation preadaptation promote VBNC formation by decreasing the intracellular ATP level. • Cross-stress protection exhibited organism-specific characteristics and could promote VBNC E. coli formation. • Food materials should avoid acidic environment, hot environment and long-term storage to reduce VBNC generation. As a novel non-thermal pasteurization technology, high pressure carbon dioxide (HPCD) has been used in food processing. However, it could induce microorganisms into a viable but nonculturable (VBNC) state, posing a potential risk to food safety and public health. In this study, we attempted to investigate the effect of various preliminary stresses including cold, heat, osmosis, acidity and oxidation on HPCD-induced VBNC formation. The results indicated that there was no effect of preliminary stresses on VBNC Staphylococcus aureus induction. However, heat, acidity and long-term (24 h) cultivation preadaptation could significantly increase the VBNC E. coli production induced by HPCD. Transcriptome analysis revealed that genes involved in ATP production were significantly decreased in these three stress-treated cells, and further ATP levels determination revealed that the ATP levels of the cell were significantly decreased after heat, acidity and long-term cultivation preadaptation, implying the decrease of ATP level caused by these stresses might be the reason for increasing VBNC production. To further study the relationship between ATP level and VBNC cell ratios after preadaptation. We artificially decreased the ATP levels, and detect their VBNC ratios after HPCD treatment. We found that with the ATP concentration decreasing after exposure to carbonyl cyanide m-chlorophenyl hydrazine (CCCP), the VBNC ratios were increased after HPCD treatment, indicating that the ATP contents were highly negatively correlated with VBNC ratios. This study proved that the preadaptation of heat, acidity and long-term cultivation could promote VBNC induction by decreasing the intracellular ATP level. In general, the obtained result gave the instruction about the storage environment for food materials, helped to further develop and optimize the HPCD processing to prevent VBNC formation and accelerate the development of HPCD technology in food industry. [ABSTRACT FROM AUTHOR]

During the pandemic of coronavirus disease 2019, the fact that frozen foods can carry the relevant virus raises concerns about the microbial safety of cold-chain foods. As a non-thermal processing technology, high pressure carbon dioxide (HPCD) is a potential method to reduce microbial load on cold-chain foods. In this study, we explored the microbial inactivation of low temperature (5-10 °C) HPCD (LT-HPCD) and evaluated its effect on the quality of prawn during freeze-chilled and frozen storage. LT-HPCD treatment at 6.5 MPa and 10 °C for 15 min could effectively inactivate E. coli (99.45%) and S. aureus (94.6%) suspended in 0.85% NaCl, SARS-CoV-2 Spike pseudovirus (>99%) and human coronavirus 229E (hCoV-229E) (>1-log virus tilter reduction) suspended in DMEM medium. The inactivation effect of LT-HPCD was weakened but still significant when the microorganisms were inoculated on the surface of food or package. LT-HPCD treatment at 6.5 MPa and 10 °C for 15 min achieved about 60% inactivation of total aerobic count while could maintain frozen state and quality of prawn. Moreover, LT-HPCD treated prawn exhibited significant slower microbial proliferation and no occurrence of melanosis compared with the untreated samples during chilled storage. A comprehensive quality investigation indicated that LT-HPCD treatment could maintain the color, texture and sensory of prawn during chilled or frozen storage. Consequently, LT-HPCD could improve the microbial safety of frozen prawn while maintaining its original quality, and could be a potential method for food industry to improve the microbial safety of cold-chain foods. • Low temperature HPCD (LT-HPCD) can achieve certain microbial inactivation. • LT-HPCD can maintain the frozen state and the quality of frozen prawn. • LT-HPCD inhibits microbial proliferation and melanosis of prawn during chill storage. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO 2 has been studied in 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([Bmim][CF 3 SO 3 ])/propylene carbonate (PC) solution on Au electrode. The linear sweep voltammetry measurements show that [Bmim][CF 3 SO 3 ] has significant catalytic effect toward CO 2 reduction. In order to study the mechanism of CO 2 reduction in [Bmim][CF 3 SO 3 ]/PC on Au electrode, the electrochemical impedance spectroscopy is employed. The experiment results show that the electrochemical impedance spectroscopy detected in [Bmim][CF 3 SO 3 ]/PC is different from that detected in tetrabutylammonium trifluoromethanesulfonate ([Bu 4 N][CF 3 SO 3 ])/PC solution. The reasonable explanation is that [Bmim] + is absorbed on the Au electrode, leading to the formation of ionic liquid film. During the CO 2 reduction process, absorbed CO 2 is reduced to CO 2 − radical via single electron transfer. The generated CO 2 − radical interacts with [Bmim] + and inducing the formation of [Bmim-CO 2 ] (ad) . Thus, the activation energy and overpotential of CO 2 reduction are reduced. The electrochemical impedance spectroscopy can be used as a methods to investigate the mechanism of CO 2 reduction in non-aqueous solution. [ABSTRACT FROM AUTHOR]

Abstract: High pressure phase behavior of the CO2 +2-ethoxyethyl methacrylate (2-EEMA) and CO2 +2,3-epoxypropyl methacrylate (2,3-EPMA) systems has been investigated in static method at five temperatures of 313.2, 333.2, 353.2, 373.2 and 393.2K and pressures up to 21.3MPa. Both CO2 +2-EEMA and CO2 +2,3-EPMA systems have continuous critical mixture (locus) curves that exhibit maximums in pressure–temperature space between the critical temperatures of CO2 and 2-EEMA or 2,3-EPMA. The solubility of 2-EEMA and 2,3-EPMA for the CO2 +2-EEMA and CO2 +2,3-EPMA systems increases as the temperature increases at fixed pressure. The CO2 +2-EEMA and CO2 +2,3-EPMA systems exhibit type-I phase behavior. The experimental results for the CO2 +2-EEMA and CO2 +2,3-EPMA systems are correlated with Peng–Robinson equation of state using a mixing rule including two adjustable parameters. The critical properties of 2-EEMA and 2,3-EPMA are predicted with Joback–Lyderson and Lee–Kesler method. [Copyright &y& Elsevier]

Abstract: Pressure-composition (P–x) isotherms were obtained for the carbon dioxide+4-chlorostyrene (4-CS) system using static apparatus at five temperatures (313.2, 333.2, 353.2, 373.2 and 393.2K) and pressure up to 23.74MPa. The experimental results for the carbon dioxide+4-CS system were modeled with the Peng–Robinson equation of state (PR EOS) using two adjustable parameters. The comparison between the experimental results and the calculated curves shows a good agreement at five temperatures. Three phases were not observed at any five temperatures in this system. The experiments were conducted to obtain cloud-point data of binary and ternary mixture for the poly(4-chlorostyrene) [P(4-CS), Mw=87,000, Mn=57,000, polydispersity=1.53]+supercritical solvents (propane, propylene, butane and 1-butene)+acetone, the P(4-CS)+supercritical solvents [butane, 1-butene and dimethyl ether (DME)]+4-CS and the P(4-CS)+supercritical solvents (butane and 1-butene)+ethanol, the P(4-CS)+supercritical solvents (propylene, 1-butene and DME) and the P(4-CS)+carbon dioxide+DME systems. High pressure phase behavior experiment for the binary and ternary mixture of the P(4-CS)+supercritical solvents+cosolvent systems is measured within a temperatures range of 332.8–494.2K and pressure up to ca. 260.0MPa. The P(4-CS)+supercritical solvents (propane, propylene and 1-butene)+acetone systems show the changes in the pressure–temperature (p–T) curve from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region as acetone concentration increases. The phase behavior curves for the P(4-CS)+supercritical solvents (butane, 1-butene)+4-CS systems of three systems [the P(4-CS)+4-CS mixture in supercritical solvents (butane, 1-butene and DME)] exhibit UCST region with negative slopes, but in the case of the P(4-CS)+DME+4-CS system, cloud-point behavior shows LCST-type curve with a positive slope. The cloud-point behaviors for P(4-CS)+supercritical solvents (butane and 1-butene)+ethanol systems exhibit USCT-type curves with negative slopes. The P(4-CS)+carbon dioxide+ x wt.% DME system shows cloud-point curves changing from UCST region to LCST region as DME concentration increases. [Copyright &y& Elsevier]

• Experimental platform established for sCO 2 mini-channel flow local visualization. • Quantitative procedures established for sCO 2 boundary in field info extraction. • Rapid density decreases and small t differences (0.01 K) under sCO 2 local heating. • Grouped nu trends found for the first time during local boundary visualization. This study is focused on measuring the transient boundary heat transfer in supercritical CO 2 mini-channel flows under local heat application. A pixelated-array masked phase-shifting interferometer system and quantitative data procedures have been established for sCO 2 boundary flow. The experiments have been conducted at a Reynolds number level of 104, spanning across both subcritical and supercritical regions (5.0 ∼ 7.9 MPa). High resolution local density and temperature have been extracted from the raw interferograms by developing a digital phase-shifting algorithm. The temporal and spatial evolutions of Nu show good agreement with classic correlations. The effects of differential pressures (10.87 ∼ 52.59 Pa) and heat fluxes (2014, 5500, 14,057 W/m2), along with their associated heat transfer behaviors, have been quantitatively examined under transient scenarios using the current method. The results show: (1) although the Re number is high, such small thermal perturbations can be clearly visualized in the entire window, which shows the capability of field extraction of the current method proposed for complicated supercritical boundary flows; (2) rapid density decrease (1.0 kg/m3) occurs locally, while small temperature differences (0.01 K) are observed, which also lead to local Nu variations under different operation conditions; (3) detailed convective patterns and time evolution of Nu curve groups identified for subcritical, near-critical and supercritical states. [ABSTRACT FROM AUTHOR]

[Display omitted] • pH ex3 is the main factor of HPCD for VBNC induction. • HP promotes HPCD-induced VBNC formation by increasing cell membrane permeability. • HP reduced the count of HPCD-induced VBNC cells by destroying the membrane. • Genes involved in transport and localization are crucial for VBNC induction. High pressure carbon dioxide (HPCD) has been used in food processing as a non-thermal pasteurization technology. However, the potential of HPCD to induce viable but non-culturable (VBNC) cells limits its application. The objective of this study was to explore the roles of extracellular pH of 3 (pH ex3) and high pressure (HP) of HPCD during VBNC induction and the underlying molecular mechanism. By using the model organism Escherichia coli O157:H7, we found that the combined effects of pH ex3 and HP could mimic the effect of HPCD for VBNC induction. Further investigation of the individual effect of pH ex3 and HP on VBNC induction revealed that pH ex3 could induce a higher proportion of VBNC cells with a slower induction rate compared with HPCD, whereas HP was unable to induce VBNC formation. Notably, the cells treated by pH ex3 and HPCD had similar morphological changes, and VBNC cells induced by pH ex3 and HPCD had similar stress resistance characteristics. These results strongly indicated that pH ex3 introduced by HPCD was a main factor for VBNC induction. Additionally, we found that HP played the role in accelerating VBNC formation in the process of HPCD treatment. Transcriptomic analysis revealed 85, 263 and 529 differentially expressed genes (DEGs) for HP-, pH ex3 - and HPCD-treated cells compared with untreated ones. 59 DEGs shared by pH ex3 and HPCD treatment might be responsible for VBNC induction, and they were mainly involved in cellular transport and localization. [ABSTRACT FROM AUTHOR]

C@Fe 2 C/TiO photocatalytic CO 2 realizes C–C coupling to produce C2 fuel mainly due to the formation of a Z-scheme heterojunction between Fe 2 C and TiO, which changes the electron transmission path, and the CO* generated by TiO induces the production of C2. [Display omitted] • A novel C@Fe 2 C/TiO ternary composite catalyst is prepared. • The catalyst exhibits high activity under simulated sunlight with main-product of C 2 H 4. • The catalyst could be excited by NIR lights. CO 2 conversion is of great industrial importance in reducing green-house effect and reusing carbon-resource. Most studies are focused on the thermocataltic CO 2 conversion, which usually performs over noble metal catalysts at high temperature and pressure. Recently, photocatalytic CO 2 conversion has caused increasing attention owing to the energy save, low-cost and clean reaction route. The key problem is to design photocatalysts high activity and strong durability. Here, we choose to prepare a novel C@Fe 2 C/TiO ternary composite catalyst by reducing organic compounds under an ammonia atmosphere. During CO 2 reduction reaction in aqueous solution, the catalyst exhibits high activity under simulated sunlight with main-product of C 2 H 4 (35.483 μmol g-1h−1). Even irradiating with near-infrared lights, the catalytic conversion still proceeds successfully, but the main-product turns to be CH 4 (18.315 μmol g-1h−1). Based on the chanracterizations and DFT calculation, the high activity could be attributed to the cooperation between the Fe 2 C catalyst toward C 2 H 4 and the TiO 2 photocatalyst. Specially, C@Fe 2 C/TiO could be excited by NIR lights owing to the narrow-energy band gap. More importantly, the photoelectrons could be easily separated from holes owing to the presence of the Z-scheme heterojunctions, leading to the enhanced photocatalytic activity. This work provides new insights to understand the CO 2 reduction reaction mechanism to develop photocatalysts. [ABSTRACT FROM AUTHOR]

Abstract: Three different supercritical fluids, CO2, dimethyl ether (DME), and chlorodifluoromethane (CHClF2), were investigated as potential solvents for processing two (meth)acrylate polymers. High pressure phase behavior data to 505K and 265.7MPa were reported for poly(hydroxypropyl methacrylate) [PHPMA] and poly(hydroxypropyl acrylate) [PHPA] in the supercritical fluid solvents+cosolvent system. Cloud-point curves for the PHPA and PHPMA in the supercritical DME show about a 40.0MPa pressure difference of constant temperature at ∼373K. The phase behavior for the PHPMA+DME+2-hydroxypropyl methacrylate (2-HPMA) and PHPA+DME+2-hydroxypropyl acrylate (2-HPA) systems were measured from changes of the pressure–temperature curve slope, and with cosolvent concentrations of w 3 =0–0.463 (2-HPMA) and w 3 =0–0.453 (2-HPA), respectively. The PHPMA+DME+ w 3 =0.0–0.238 CO2 and PHPA+DME+ w 3 =0.0–0.210 CO2 mixture show UCST-type behavior with a negative slope, and then the pressure increases smoothly for temperatures in the range of 323–492K. PHPMA and PHPA do not dissolve in pure CO2 at a temperature of 518K and pressure of 280.0MPa. The location of the PHPMA+CO2 cloud-point curve shifts to lower temperatures and pressures when w 3 =0.40–0.66 2-HPMA was added to the PHPMA+CO2 solution. The phase behavior for the PHPA+CO2 + w 3 =0.35–0.68 2-HPA system changes the pressure–temperature curve from an upper critical solution temperature (UCST) region to a lower critical solution temperature (LCST) region as the 2-HPA concentration increases. The PHPMA+CO2 + w 3 =0.689 2-HPMA phase behavior curve intersects a fluid→liquid+vapor (LV) curve at ∼393K and ∼16.0MPa. [Copyright &y& Elsevier]

[Display omitted] • Three ZnAl 2 O 4 surfaces and their activities were theoretically studied. • The stability of ZnAl 2 O 4 decreases in the trend of (1 0 0) > (1 1 1) > (1 1 0). • ZnAl 2 O 4 (1 1 1) is the active surface for syngas to methanol conversion. • Stepwise pathway involving formate moiety dominates initial CO activation. • Activity plot with CO conversion and temperature was revealed. Identifying active site structure and unveiling corresponding reaction pathways are crucial issues to construct compatible reactive components in bifunctional catalysts for direct syngas conversion. Herein, the active surface structure and the reaction mechanism of syngas conversion to bridging intermediate methanol on ZnAl 2 O 4 spinel oxide are systematically investigated by combining density functional theory calculations and microkinetic simulations. The hydroxylated oxygen-rich surfaces of ZnAl 2 O 4 are demonstrated and their stabilities decreases as (1 0 0)-B-1/4H > (1 1 1)-B-3/8H > (1 1 0)-B-1/4H. Four reaction pathways differentiating in the adsorption site of CO and the participation style of H 2 on these surfaces are kinetically compared. We reveal that ZnAl 2 O 4 (1 1 1) is the active surface for syngas conversion; CO bonding on O site is activated more readily in a stepwise way to CH 2 O and the concerted pathway is then followed for CH 2 O to methanol. On ZnAl 2 O 4 (1 0 0) and ZnAl 2 O 4 (1 1 0) surfaces, the Non-Horiuti-Polanyi pathway in which gaseous H 2 reacting directly with CO or CH 2 O becomes kinetically more important. The Zn-O site of ZnAl 2 O 4 (1 1 1) is essential to dissociate H 2 heterolytically and stabilize key intermediate CHO. We show that the reaction rate decreases with the CO conversion, and the simulated reaction rate (~13 s−1) at 8% conversion agrees quite well with the experimental one (~20 s−1) under the typical reaction conditions. The predicted activity plots with temperature and CO conversion highlight the driving essentiality of zeolite component in bifunctional catalysts for syngas conversion. [ABSTRACT FROM AUTHOR]

The boundary heat transfer dynamics of supercritical carbon dioxide (CO 2) is vital to its application in solar heater, extraction, refrigeration, heat pumps, power generations, nuclear systems and many other occasions. In this study, an experiment system using pixelated-array masked phase-shifting interferometer has been established for the visualization of temperature of supercritical CO 2. The laser diagnostic process has been operated with a carefully designed visualization chamber to give clear transient results of the density and temperature fields for the first time. Those field information has been used to calculate the heat transfer characteristic parameters of the supercritical CO 2 fluid in different boundary conditions. The current quantitative visualization analysis by the utilization of pixelated methods is shown capable of giving transient analysis of detailed field evolutions. The results show that (1) small temperature differences are generated in supercritical boundary due to the typical large thermal capacity; (2) supercritical convection boundary is with much quicker thermal quenching than subcritical states, while the subcritical states boundary parameter show localized characteristics while supercritical cases show fluctuation phenomena; (3) the boundary fluctuations heat transfer field exist for supercritical states and the fluctuations affect the overall heat transfer behaviour and the field evolution in supercritical states. [ABSTRACT FROM AUTHOR]

Ionic porous organic polymers with high surface area and desirable ionic density are obtained by crosslinking strategy and these polymers have shown remarkable catalytic performance for the cycloaddition reaction of CO 2 with epoxides under mild conditions. [Display omitted] • Crosslinking strategy is proposed to improve the specific surface area of IPOPs. • IPOP1-XL and IPOP2-XL are successfully synthesized by crosslinking strategy. • IPOP1-XL and IPOP2-XL both possess excellent porosity and preferable ionic density. • IPOP1-XL shows remarkable catalytic performance in CO 2 chemical fixation. Ionic porous organic polymers (IPOPs) emerge as porous networks with charged characteristics for versatile applications. However, most of the reported IPOPs have suffered from poor porosity due to the presence of electric charges in the synthesis process. Until now, it is a challenge to obtain IPOPs with both great porosity and high ionic density. Herein, we demonstrate a simple crosslinking strategy to integrate large specific surface area and abundant ionic sites in IPOPs (named as IPOPs-XL). Especially, IPOP1-XL synthesized via crosslinking strategy exhibits a large Brunauer–Emmett–Teller (BET) specific surface area of 1830 m2 g−1, which is 18 times higher than that of the pyridine-based polymer before crosslinking (IPOP-1, 96 m2 g−1). The uptake capacity for carbon dioxide (CO 2) of IPOP1-XL (11.7 wt%) is also much higher than that of IPOP-1 (4.5 wt%) at 273 K due to the enhanced porosity. Meanwhile, IPOP1-XL also possesses an improved ionic density (3.5 mmol g−1), which plays a pivotal role in CO 2 chemical fixation. This work provides a feasible method to improve the porosity of IPOPs. [ABSTRACT FROM AUTHOR]