Low Conversion Research Articles

Clinical significance of appendicoliths in elderly patients over eighty years old undergoing emergency appendectomy: A single-center retrospective study

BACKGROUND Acute appendicitis with an appendicolith is one of the most common abdominal emergencies in elderly patients and is more likely to progress to gangrene and perforation. AIM To analyze the clinical data of elderly patients undergoing emergency appendectomy for acute appendicitis, aiming to improve treatment strategies. METHODS The clinical data of 122 patients over 80 years old who underwent emergency appendectomy for acute appendicitis at the Department of Emergency Surgery of Zhongshan Hospital, Fudan University from January 2016 to March 2023 were retrospectively analyzed. The patients were divided into two groups based on the presence of an appendicolith or not, and clinicopathological and surgery-related features were compared between the two groups. RESULTS The duration of abdominal pain in all 122 patients ranged from 5 to 168 h. All patients underwent emergency appendectomy: 6 had an open appendectomy, 101 had a laparoscopic appendectomy, and 15 required conversion from laparoscopic to open surgery, resulting in a conversion rate of 12.9% (15/116). The patients were divided into two groups: Appendicolith group (n = 46) and non-appendicolith group (n = 76). Comparisons of clinicopathological features revealed that patients with appendicoliths were more likely to develop appendiceal gangrene (84.8% vs 64.5%, P = 0.010) and perforation (67.4% vs 48.7%, P = 0.044), and had a lower surgical conversion rate (2.2% vs 19.7%, P = 0.013). The median length of hospital stay was 5.0 d for both groups and there was no significant difference between them. All patients were successfully discharged. CONCLUSION Around 40% of patients over 80 years old with acute appendicitis have an appendicolith, increasing their risk of developing appendiceal gangrene and perforation, and therefore should receive timely surgical treatment.

Urgent Versus Elective Laparoscopic Cholecystectomy Following Percutaneous Transhepatic Gallbladder Drainage for Moderate Acute Cholecystitis: A Meta-Analysis

Background There is still controversy regarding the treatment strategy for moderate acute cholecystitis (AC). Percutaneous transhepatic gallbladder drainage (PTGBD) followed laparoscopic cholecystectomy (LC) has shown advantages compared to emergency LC (ELC). However, the results are controversial. Therefore, we conducted this updated meta-analysis to clarify this issue. Materials and Methods A comprehensive literature search for relevant studies comparing the PTGBD + LC and ELC for moderate AC was performed. The statistical analysis was conducted using Stata. Results A total of 14 studies were included. The pooled analysis revealed that PTGBD + LC group had a shorter operation time (SMD = −1.07, 95%CI = −1.19 to −0.95), lower amount of intraoperative bleeding (SMD = −0.93, 95%CI = −1.07 to −0.79), lower conversion rate (OR = 0.28, 95% CI = 0.17-0.44), lower postoperative complications (OR = 0.45, 95% CI = 0.23-0.88) shorter postoperative hospital stay (SMD = −1.20, 95%CI = −1.33 to −1.07), lower wound infection rate (OR = 0.41, 95%CI = 0.23-0.74) and higher hospitalization expenses (SMD = 1.13, 95%CI = 0.96 to 1.29) compared with ELC group. There was no significant difference in the incidence of bile leak, bile duct injury and total hospital stay. Conclusion This meta-analysis suggested that PTGBD + LC has significant advantages over ELC for moderate AC patients, including lower surgical difficulty, lower conversion rate, fewer postoperative complications, and shorter hospital stay.

Dual‐Site NiO/Bi3O4Br Heterojunction Catalyst for High‐Efficiency CO2‐to‐CH4 Conversion

AbstractSolar light‐driven conversion of CO2 into chemicals with high calorific value is regarded as an upcoming carbon utilization technology for alleviating the energy crisis. This technique faces the challenge of low CO2 conversion and product yield due to charge recombination in the catalyst. In this paper, a dual‐reaction site heterojunction catalyst was designed and fabricated by combining NiO with Bi3O4Br nanosheets, for the separation of CO2 reduction and H2O oxidation semireactions, which effectively promoted electrons and holes separation. The resulting catalyst exhibited a high CH4 production rate (8.12 µmol/g) and selectivity (94.69%). Electron distribution and band structure were investigated to explain the satisfactory catalytic performance. In addition, combining the in‐situ DRIFTS results, a formic acid‐intermediated CO2‐to‐CH4 reaction pathway was proposed. This work aims to pave the way for CH4 production via CO2 photoreduction with high efficiency and selectivity.

A cascade X-ray energy converting approach toward radio-afterglow cancer theranostics.

Leveraging X-rays to initiate prolonged luminescence (radio-afterglow) and stimulate radiodynamic 1O2 production from optical agents provides opportunities for diagnosis and therapy at tissue depths inaccessible to light. However, X-ray-responsive organic luminescent materials are rare due to their intrinsic low X-ray conversion efficiency. Here we report a cascade X-ray energy converting approach to develop organic radio-afterglow nanoprobes (RANPs) for cancer theranostics. RANPs comprise a radiowave absorber that down-converts X-ray energy to emit radioluminescence, which is transferred to a radiosensitizer to produce singlet oxygen (1O2). 1O2 then reacts with a radio-afterglow substrate to generate an active intermediate that simultaneously decomposes to emit radio-afterglow. Through finetuning such a cascade, intraparticle radioluminescence energy transfer and the 1O2 transfer process, RANPs possess tunable wavelengths and long half-lives, and generate radio-afterglow and 1O2 at tissue depths of up to 15 cm. Moreover, we developed a biomarker-activatable nanoprobe (tRANP) that produces a tumour-specific radio-afterglow signal, leading to ultrasensitive detection and the possibility of surgical removal of diminutive tumours (1 mm3) under an X-ray dosage 20 times lower than inorganic materials. The efficient radiodynamic 1O2 generation of tRANP permits complete tumour eradication at an X-ray dosage lower than clinical radiotherapy and a drug dosage one to two orders of magnitude lower than most existing inorganic agents, leading to prolonged survival rates with minimized radiation-related adverse effects. Thus, our work reveals a generic approach to address the lack of organic radiotheranostic materials and provides molecular design towards precision cancer radiotherapy.

Etherification of isoamyl alcohol using Amberlyst®15 as an acid catalyst

The present work reports on the production of di-isoamyl ether from the etherification of isoamyl alcohol, using the sulphonic resin Amberlyst®-15 (A-15) as a catalyst. Parameters such as temperature, reaction time and amount of catalyst were studied. Although the etherification reaction shows low conversions (9-18%), when glycerol is added to the reaction medium and an external pressure to the reaction system (3.5 atm), the conversion increases up to 40% and a yield up to 100% can be obtained towards di-isoamyl ether.

Hepatic Transcriptomics of Broilers with Low and High Feed Conversion in Response to Caloric Restriction

Background: In broiler chickens, the efficient utilization of macro- and micronutrients is influenced by various metabolic pathways that are closely linked to feed efficiency (FE), a critical metric in poultry industry, with residual feed intake (RFI) as the preferred proxy. Feed restriction is considered an approach to address the underlying molecular mechanisms of feed conversion. We hypothesized that broiler chickens with divergent RFI subjected to quantitative feed restriction differ in their pattern of molecular pathways for efficient nutrient utilization in liver as post-absorptive tissue. Methods: Cobb 500FF broiler chickens divergent for RFI (n = 112) were feed-restricted from day 9 until market weight at day 33–37 post-hatch. Based on a previous trial, feed restriction levels were set at 92% (low-RFI birds) and 80% (high-RFI birds) relative to the control groups. Transcriptomic analyses of the liver were conducted. Results: Due to the interaction of the RFI group and feeding regimen, a total of 140 to 507 differentially expressed genes were identified for the respective contrasts, with implications for hepatic metabolism and cellular stress response. Although the broilers did not realize their full growth potential under restrictive feeding (12.4% reduced body weight vs. controls, p = 0.094), the gene expression patterns indicate a lower susceptibility to blood coagulation (KNG1, FGG, and FGB), suggesting that controlled and mild feed restriction could lead to health benefits in less feed-efficient broilers. Moreover, FE traits are shown to be linked to cellular detoxification processes (MGST3 and CYP2AC2) and triacylglycerol syntheses (MOGAT1 and LPIN1). Conclusions: Divergent transcriptional profiles between broiler groups under varied caloric conditions indicate potential for optimizing nutritional management strategies.

2-O-α-D-glucosyl glycerol production by whole-cell biocatalyst of lactobacilli encapsulating sucrose phosphorylase with improved glycerol affinity and conversion rate.

2-O-α-D-glucosyl glycerol (2-αGG) is a valuable ingredient in cosmetics, health-care and food fields. Sucrose phosphorylase (SPase) is a favorable choice for biosynthesis of 2-αGG, while its glucosyl-acceptor affinity and thermodynamic feature remain largely unknown, limiting 2-αGG manufacturing. Here, three SPases were obtained from lactobacilli and bifidobacteria, and the one encoded by Lb. reuteri SDMCC050455 (LrSP) had the best transglucosylation ability, with 2-αGG accounting for 86.01% in the total product. However, the LrSP exhibited an initial forward reaction rate of 11.83/s and reached equilibrium of 56.90% at 110h, indicating low glycerol affinity and conversion rate. To improve catalytic efficiency, the LrSP was overexpressed in Lb. paracasei BL-SP, of which the intracellular SPase activity increased by 6.67-fold compared with Lb. reuteri SDMCC050455. After chemically permeabilized with Triton X-100, the whole-cell biocatalysis of Lb. paracasei BL-SP was prepared and showed the highest activity, with the initial forward reaction rate improved to 50.17/s and conversion rate risen to 80.79% within 17h. Using the whole-cell biocatalyst, the final yield of 2-αGG was 203.21g/L from 1M sucrose and 1M glycerol. The food grade strain Lb. paracasei was used for the first time as cell factory to recombinantly express the LrSP and construct a whole-cell biocatalyst for the production of 2-αGG. After condition optimization and cell permeabilization, the whole-cell biocatalyst exhibited 23.89% higher equilibrium conversion and 9.10-fold of productivity compared with the pure enzyme catalytic system. This work would provide a reference for large-scale bioprocess of 2-αGG.

Production of Tagatose from Galactose with CaO at Room Temperature

This study investigates the efficacy of Sn‐β zeolite, triethylamine, and CaO in the isomerization of galactose to tagatose. At temperatures over 80 °C, all three reagents exhibited low tagatose yield (< 20%). Notably, at 100 °C and a CaO/galactose molar ratio of 1/5, a galactose conversion of 64% was achieved with a tagatose selectivity of 17%. The tagatose selectivity decreased over time at this temperature. However, at room temperature, a tagatose selectivity of 56% and 73% with a CaO to galactose molar ratio of 1/1 and 2/1 respectively was obtained with a 100% galactose conversion after 40 min of reaction. The galactose conversion had a linear relationship with the molar ratio of CaO/galactose at room temperature. This indicates that CaO functions as a stoichiometric reagent rather than a catalyst. A yellowish gel‐like complex formed when the CaO/galactose molar ratios exceeded 1/2. It is noteworthy that these phenomena were not observed with MgO. In addition, low isomerization conversion from glucose to fructose was observed with CaO.

HPB SO08 - Safety of Robotic cholecystectomy as index training procedure – the UK experience

Abstract Background A recent large retrospective cohort study reported a higher risk of bile duct injury associated with robotic cholecystectomy when compared to the laparoscopic approach. Considering that most robotic training pathways, including the one followed in the UK, utilise robotic cholecystectomy as index training procedure, such findings mandate evaluation of the safety profile of robotic cholecystectomy in the UK to ensure its use as an alternative approach to laparoscopic cholecystectomy is not putting patients at risk. We aimed to conduct a multi-centre observational study to evaluate the safety profile of robotic cholecystectomy performed within the UK HPB Robotic training program. Method A retrospective analysis of prospectively collected data from eleven centres participating in the UK robotic HPB training program was conducted. All adult patients undergoing robotic cholecystectomy for symptomatic gallstone disease or gallbladder polyp were considered. Bile duct injury, conversion to open procedure, conversion to subtotal cholecystectomy, length of hospital stay, 30-day re-admission, and post-operative complications were the evaluated outcome parameters. Results A total of 600 patients were included. The median age was 53 (IQR 65 - 41) years and the majority (72.7%; 436/600) were female. The main indications for robotic cholecystectomy were biliary colic (55.5%, 333/600), cholecystitis (18.8%, 113/600), gallbladder polyps (7.7%, 46/600) and pancreatitis (6.2%, 37/600). The median length of stay was 0 (IQR: 0-1) days. Of the included patients, 88.5% (531/600) were discharged on the day of procedure with 30-day re-admission rate of 5.5% (33/600). There were no bile duct injuries and the rate of conversion to open was 0.8% (5/600) with subtotal cholecystectomy rate of 0.8% (5/600). Conclusion This current study confirms that robotic cholecystectomy can be safely implemented to routine practice with a low risk of bile duct injury, low conversion to open surgery and low need for subtotal cholecystectomy.

Hydrogen isotope fractionation during aromatization to form alkylnaphthalene: Insights from pyrolysis experiments of 1-n-butyldecalin

Alkylnaphthalene homologues are important components of aromatic fraction in sedimentary organic matter and contain significantly geochemical information relative to formation and evolution of the host organic matter. They mainly originate from hydrocarbon aromatization reaction which involves the dehydrogenation of aliphatic rings resulting in the fractionation of stable hydrogen isotopes between aromatic hydrocarbons and their precursors. To examine these processes, this study thermally pyrolysed 1-n-butyldecalin (BD) at different time intervals under 360 °C/50 MPa to study the aromatization and hydrogen isotope fractionation during alkylnaphthalene formation and evolution. The relative content of aromatic products, such as naphthalene (N) and 1-methylnaphthalene (1-MN), increases with increasing aromatization. Sulfur enhanced the degree of aromatization during BD thermal evolution, resulting in greater N and 1-MN formation. For the compounds with the same carbon skeleton, i.e. tran-1-methyldecalin (1-MD), 5-methyltetraline (5-MT) and 1-MN, the 2H enrichment follows the order δ2H1-MD < δ2H5-MT < δ2H1-MN during the low thermal conversion of BD. However, the order was subsequently destroyed with increasing aromatization. The results indicate that hydrocarbon aromatization can enrich aromatic hydrocarbon in 2H, resulting in a higher δ2H value of higher aromatic-ring-number hydrocarbon than that of a lower aromatic-ring-number at low aromatization. However, 2H enrichment will decrease and even result in a reverse order with enhanced aromatization. Our findings are beneficial for understanding genetic mechanism and hydrogen isotope fractionation effect during the formation and evolution of aromatic hydrocarbons.

High‐Performance Infrared Scene Generation Using a Double‐S Microbridge Photothermal Film Emitter With Ultralarge Array

AbstractInfrared emitters are highly desirable for applications in infrared imaging and stealth technology. Photothermal film emitters, which are driven by light, have garnered considerable interest due to their excellent photothermal properties and ease of fabrication. However, existing photothermal films often suffer from low photothermal conversion efficiency (PCE) and limited array scale. Here, a photothermal film emitter featuring a double‐S microbridge structure is presented, which comprehensively considering the PCE and frame rate. Initially, Si microbridges are fabricated within each microstructure to support the photothermal film. The pattern structure is then arranged into a double‐S configuration to manipulate the thermal conductivity. By optimizing the length and width of the double‐S pattern, high PCE and fast frame rates are achieved. The double‐S microbridge structure photothermal film emitter is fabricated with a 4‐inch diameter, forming an ultra‐large array with over 3000 × 3000 pixels. The absorption and photothermal conversion characteristics are studied, revealing a maximum temperature of 582.70 K and a highest PCE of 16.32%. Time‐dependent photothermal response demonstrated the emitter's rapid heat storage and release capabilities. Additionally, an infrared scene generator is realized. These results position the photothermal film emitter as a promising solution for infrared imaging and dynamic scene generation.

Altered Steroidome in Women with Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) mainly afflicting young women. Various steroids can influence the onset and development of the disease or, on the contrary, mitigate its course; however, a systematic review of steroidomic changes in MS patients is lacking. Based on the gas chromatography tandem mass spectrometry (GC-MS/MS) platform and, in the case of estradiol, also using immunoassay, this study performed a comprehensive steroidomic analysis in 25 female MS patients aged 39(32, 49) years compared to 15 female age-matched controls aged 38(31, 46) years. A significant trend towards higher ratios of conjugated steroids to their unconjugated counterparts was found in patients, which is of particular interest in terms of the balance between excitatory and inhibitory steroid modulators of ionotropic receptors. Patients showed altered metabolic pathway to cortisol with decreased conversion of pregnenolone to 17-hydroxypregnenolone and 17-hydroxypregnenolone to 17-hydroxyprogesterone and increased conversion of 17-hydroxypregnenolone to dehydroepiandrosterone (DHEA), resulting in lower levels of 17-hydroxyprogesterone, as well as indications of impaired conversion of 11-deoxy-steroids to 11β-hydroxy-steroids but reduced conversion of cortisol to cortisone. Due to over-activation of hypothalamic-pituitary-adrenal axis (HPAA), however, cortisol and cortisone levels were higher in patients with indications of depleted cortisol synthesizing enzymes. Patients showed lower conversion of DHEA to androstenedione, androstenedione to testosterone, androstenedione to estradiol in the major pathway, and testosterone to estradiol in the minor pathway for estradiol synthesis at increased conversion of androstenedione to testosterone. They also showed lower conversion of immunoprotective Δ5 androstanes to their more potent 7α/β-hydroxy metabolites and had lower circulating allopregnanolone and higher ratio 3β-hydroxy-steroids to their neuroprotective 3α-hydroxy-counterparts.

Primary Open-Angle Glaucoma Polygenic Risk Score and Risk of Disease Onset

Primary open-angle glaucoma (POAG) is a heritable disease. A polygenic risk score (PRS) threshold may be used to identify individuals at low risk of disease onset. To assess the utility of a POAG PRS to identify ocular hypertensive individuals at low risk of disease onset. This is a post hoc analysis of the Ocular Hypertension Treatment Study (OHTS), a multicenter randomized clinical trial across 22 centers in the US conducted among 1636 participants with ocular hypertension from February 1994 to April 2019 with available genetic data. Of the 1636 original participants, 1077 had available genetic data; after excluding 67 for missing data, data quality concerns, or ancestry other than European or African, 1010 were included in the present analysis. Data for this report were analyzed from November 2023 to June 2024. From 1994-2002, participants were randomized to receive topical intraocular pressure (IOP)-lowering medications. From 2002 onwards, all participants were given topical IOP-lowering medications. Twenty-year conversion rates by POAG PRS threshold, baseline randomization status, and OHTS clinical risk tertile. Among the 1010 participants in this study, 563 (65.8%) were female, and the mean (SD) age was 55.9 (9.4) years. In a mixed-effects logistic regression model adjusted for OHTS risk factors for conversion to POAG and randomization status, a PRS under the 48th percentile was associated with a 1.49 times higher likelihood of disease-free status after 20 years of follow-up (95% CI, 1.04-2.15; P = .03; unadjusted hazard ratio [HR], 1.64; 95% CI, 1.13-2.38; P = .009), compared with high polygenic risk. When we stratified the trial cohort into nongenetic OHTS clinical risk tertiles, the largest differences in survival probability at 20 years based on PRS threshold was observed in eyes in the highest tertile, initial observation group (20-year conversion rate: 61.1% in the high polygenic risk group vs 23.8% in the low polygenic risk group; 95% CI, -63.0 to -11.6; P = .01), with randomization to early treatment partially mitigating the effect of high genetic risk (20-year conversion rate: 37.3% in the high polygenic risk group vs 24.1% in the low polygenic risk group; 95% CI, -35.6 to 9.3%; P = .32). These findings support considering use of a POAG PRS threshold to identify individuals at low risk of disease onset, with those below the PRS threshold more likely to have lower conversion rates over 20 years. Among those considered at highest risk based on the OHTS clinical risk model, early treatment may partially offset the association with high genetic risk but provide limited benefit for those with low genetic risk. ClinicalTrials.gov Identifier: NCT00000125.

CO2-free production of hydrogen via pyrolysis of natural gas: influence of non-methane hydrocarbons on product composition, methane conversion, hydrogen yield, and carbon capture

Methane pyrolysis represents a CO2-free hydrogen production route that enables simultaneous carbon capture. While the majority of previous studies in the field focus on pure CH4 as feed gas stream, commercial processes will typically rely on natural gas as feedstock that contains also non-methane hydrocarbons such as ethane, propane, and n-butane. Therefore, the present study evaluates how CH4 conversion, H2 selectivity, product composition, and solid carbon yield evolve when using either pure CH4 or synthetic natural gas (SNG) as feed gas stream for a thermal pyrolysis process in a lab-scale high-temperature reactor. For this, industrially viable conditions are applied, namely temperatures between 1000 °C and 1600 °C, residence times between 1 s and 7 s, and molar H2 dilution ratios between 1:1 and 4:1. Although the use of SNG results in slightly lower hydrocarbon conversions because the additional components in SNG result in a higher effective H2 dilution ratio compared to a CH4-only feed, the non-methane hydrocarbons in the SNG have a positive effect on both H2 selectivity and solid carbon yield. Taking existing mechanistic understanding into account, these positive effects are attributed to radicals formed from the non-methane hydrocarbons, which facilitate dehydrogenation steps from ethane to ethylene and hereby increase the relative amount of H2 originating from CH4. The introduction of a carbonaceous fixed bed further benefits the performance of the pyrolysis process and ultimately enables to capture more than 98% of carbon in its solid form under industrially viable process conditions.

Event-based high-resolution neutron image formation analysis using intensified CMOS cameras

We present a versatile optical setup for high-resolution neutron imaging with an adaptable field of view and magnification that can resolve individual neutron absorption events with an image intensifier and a CMOS camera. Its imaging performance is characterized by evaluating the resolution limits of the individual optical components and resulting design aspects are discussed. Neutron radiography measurements of a Siemens star pattern were performed in event mode acquisition comparing two common high-resolution neutron scintillators, crystalline Gadolinium Gallium Garnet (GGG) and powdered Gadolinium Oxysulfide (GOS). An analysis of the light signature caused by neutron absorption events is performed and some resulting issues for both GGG and GOS regarding optical system design are addressed. Both scintillators reach similar resolution (4–5 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\upmu }$$\\end{document}m) in event mode acquisition despite different light emission characteristics. The findings suggest that, in the case of GOS, the resolution is limited by the size of the light clusters which in turn originate from the photon scattering at the boundaries of the powder particles comprising it, while with GGG the lower light conversion efficiency makes it challenging to collect enough photons to trigger sufficient signal amplification in the image intensifier. Overall, the proposed event-based evaluation of scintillators allows for quantifying and optimizing various design parameters, which is much more complex than adopting conventional methods based on integrated images.

Simulation and Optimization of a Hybrid Photovoltaic/Li-Ion Battery System

The coupling of solar cells and Li-ion batteries is an efficient method of energy storage, but solar power suffers from the disadvantages of randomness, intermittency and fluctuation, which cause the low conversion efficiency from solar energy into electric energy. In this paper, a circuit model for the coupling system with PV cells and a charge controller for a Li-ion battery is presented in the MATLAB/Simulink environment. A new three-stage charging strategy is proposed to explore the changing performance of the Li-ion battery, comprising constant-current charging, maximum power point tracker (MPPT) charging and constant-voltage charging stages, among which the MPPT charging stage can achieve the fastest maximum power point (MPP) capture and, therefore, improve battery charging efficiency. Furthermore, the charge controller can improve the lifetime of the battery through the constant-current and constant-voltage charging scheme. The simulation results indicate that the three-stage charging strategy can achieve an improvement in the maximum power tracking efficiency of 99.9%, and the average charge controller efficiency can reach 96.25%, which is higher than that of commercial chargers. This work efficiently matches PV cells and Li-ion batteries to enhance solar energy storages, and provides a new optimization idea for hybrid PV/Li-ion systems.

Towards Photothermal Acid Catalysts Using Eco-Sustainable Sulfonated Carbon Nanoparticles—Part II: Thermal and Photothermal Catalysis of Biodiesel Synthesis

The main goal of this work is to evaluate the ability of sulfonated carbon nanoparticles (SCNs) to induce photothermal catalysis of the biodiesel synthesis reaction (transesterification of natural triglycerides (TGs) with alcohols). Carbon nanoparticles (CNs) are produced by the carbonization of cross-linked resin nanoparticles (RNs). The RNs are produced by condensation of a phenol (resorcinol or natural tannin) with formaldehyde under ammonia catalysis (Stober method). The method produces nanoparticles, which are carbonized into carbon nanoparticles (CNs). The illumination of CNs increases the temperature proportionally (linear) to the nanoparticle concentration and exposure time (with saturation). Solid acid catalysts are made by heating in concentrated sulfuric acid (SEAr sulfonation). The application of either light or a catalyst (SCNs) (at 25 °C) induced low conversions (&lt;10%) for the esterification reaction of acetic acid with bioethanol. In contrast, the illumination of the reaction medium containing SCNs induced high conversions (&gt;75%). In the case of biodiesel synthesis (transesterification of sunflower oil with bioethanol), conversions greater than 40% were observed only when light and the catalyst (SCNs) were applied simultaneously. Therefore, it is possible to use sulfonated carbon nanoparticles as photothermally activated catalysts for Fischer esterification and triglyceride transesterification (biodiesel synthesis).

Kinetic analysis on low‐temperature oxidation of wood pellets by isothermal microcalorimetry

AbstractLow‐temperature chemical oxidation is the major driver of self‐heating during storage of wood pellets and its kinetics is essential to describe the heat evolution. In the present work, isothermal microcalorimetry was used to characterize heat generation behavior of three types of wood pellets (pine, fir, and redwood pellets) at 30–70°C. The obtained data were employed to derive the kinetics of low‐temperature oxidation by the peak power, iso‐conversional method, and non‐steady analysis. The consistency and applicability of the kinetics derived by the three methods were evaluated. Kinetic parameters determined by the peak power method were observed to match those from the iso‐conversional method at lower conversions of the oxidation for heat generation. The kinetics derived by the iso‐conversional method indicated the oxidation reactivity generally decreasing and activation energy increasing with the conversion because of O2 consumption and reaction mechanism changing. With the impact of O2 consumption considered separately, the kinetics from the non‐steady analysis is capable of describing the evolution of heat power with the conversion and also consistent with that from the peak power method in describing intrinsic reactivity of pellet materials. The kinetics from the peak power and iso‐conversional methods lump the impact of O2 concentration with the reaction reactivity, suggesting their applications requiring additional models for connecting with O2 consumption.

Engineering Co Single Atoms in Ultrathin BiOCl Nanosheets for Boosted CO2 Photoreduction

AbstractDespite the development of a range of photocatalysts for CO2 reduction, the practical applications are significantly limited by low conversion efficiencies and their reliance on sacrificial agents, which are rooted in thermodynamic and kinetic challenges related to CO2 conversion. Here, the engineering of Co single atoms in ultrathin single‐crystal BiOCl nanosheets for boosted photocatalytic CO2 reduction is reported. The engineering of Co atoms modulates the distribution of photogenerated charges at the catalyst surface, controlling key surface reaction dynamics and suppressing surface electron‐hole recombination. This modulation also improves light absorption and enhances CO2 adsorption and activation, leading to more efficient surface reactions. Notably, CO2 is stably adsorbed onto the (001) face of BiOCl through a Bi‐O‐C(= O)‐Co‐O coordination unit, which lowers the activation energy for CO2 reduction and reduces the formation energy of COOH− intermediates. As a result, the BiOCl photocatalysts achieve a CO formation rate of 183.9 µmol g−1 h−1, when irradiated with a 300 W Xe lamp without cocatalysts or sacrificial agents. It represents an ≈13‐fold increase compared to that of pristine BiOCl, and surpasses most reported Bi‐based photocatalysts to date. Current work provides valuable insights into engineering of single atoms for developing advanced CO2‐reduction photocatalysts.

A dehydration membrane reactor towards highly efficient LPG synthesis via CO2 hydrogenation

In recent years, CO2 hydrogenation has garnered increasing attention as a promising avenue towards the conversion of captured CO2 to valuable liquid chemicals, including CH3OH, CH3OCH3, and liquified petroleum gas (LPG). However, chemical conversion of CO2 has proven to be immensely challenging, resulting in low CO2 conversion (<35 %) and product yields (<15 %). H2O, unavoidably evolved during CO2 hydrogenation, imposes both thermodynamic and kinetic penalties on CO2 hydrogenation reactions via adsorption on catalyst active sites and promotion of undesirable reaction pathways. In this work, to greatly facilitate direct conversion of CO2 to LPG over a bifunctional Cu/Zn/Zr on Al2O3 (CZZA)/Pd-β-zeolite catalyst, a dehydration membrane reactor (MR) featuring a H2O-conducting Na+-gated nanochannel membrane was studied. Before the incorporation of the Na+-gated membrane, the CZZA/Pd-β-zeolite was unable to produce LPG at 280–310 °C and 14 bar, and the CO2 conversion was limited to < 35 %. In stark contrast, the MR exhibited CO2 conversion and LPG yield of 72.1 % and 51.7 %, respectively. The operating conditions of the MR were systematically investigated to determine the maximum achievable performance resulting in CO2 conversion and LPG yield as high as 90.2 % and 60.5 %, respectively. Furthermore, the LPG space–time yield (STY) at the optimized conditions was near that of the best-performing traditional reactors (TRs) in the literature but at 3 times and 8 times increased CO2 conversion and time factor (W/F), respectively. The MR in this work demonstrates the synergistic efficacy of combined H2O removal and CH3OH consumption towards highly efficient hydrogenation of CO2 for LPG production.