Modelling foam drainage

Foaming occurs in many distillation and absorption processes. In this paper, two basic building blocks that are needed to model foam drainage and hence foam stability are discussed. The first concerns the flow of liquid from the lamellae to the Plateau borders and the second describes the drainage flows that occur within the borders. The mathematical modelling involves a balance between gravity, diffusion, viscous forces, and varying surface tension effects with or without the presence of monolayers of surfactant. In some cases, mass transfer through the gas-liquid interface also causes foam stabilisation, and must be included. Our model allows us to clarify which mechanisms are most likely to dominate in both the lamellae and Plateau borders and hence to determine their evolution. The model provides a theoretical framework for the prediction of foam drainage and collapse rates. The analysis shows that significant foam stability can arise from small surface tension variations

International Group Work for Sustainable Chemistry

As part of a transnational degree programme, students in the UK and China were linked together to carry out group work. This was enabled by having two versions of our FHEQ Level 4 Sustainable Chemistry module; in person for UK students, and by distance learning for Chinese students. Groups were instructed to discuss issues relating to the UN Sustainable Development Goals in their respective countries and report back individually. Students who found the assignment interesting were more likely to indicate they would keep in touch, while those students who had fewer interactions or found the assessment guidelines unclear found the assignment less interesting and were less likely to wish to remain in touch. This kind of assignment is an example of what can be done with links to other institutions around the world

The effect of surfactants on expanding free surfaces

This paper develops a systematic theory for the flow observed in the so-called ``overflowing cylinder'' experiment. The basic phenomenon to be explained is the order of magnitude increase in the surface velocity of a slowly overflowing beaker of water that is caused by the addition of a small amount of soluble surfactant. We perform analyses of (i) an inviscid bulk flow in which diffusion is negligible, (ii) a hydrodynamic boundary layer in which viscous effects become important, (iii) a diffusive boundary layer where diffusion is significant, and by matching these together arrive at a coupled problem for the liquid velocity and surfactant concentration. Our model predicts a relation between surface velocity and surface concentration which is in good agreement with experiment. However a degeneracy in the boundary conditions leaves one free parameter which must be taken from experimental data. We suggest an investigation that may resolve this indeterminacy

Fast cation-exchange separation of proteins in a plastic microcapillary disc

A novel disposable adsorbent material for fast cation-exchange separation of proteins was developed based on plastic microcapillary films (MCFs). A MCF containing 19 parallel microcapillaries, each with a mean internal diameter of 142μm, was prepared using a melt extrusion process from an ethylene-vinyl alcohol copolymer (EVOH). The MCF was surface functionalised to produce a cation-exchange adsorbent (herein referred as MCF-EVOH-SP). The dynamic binding capacity of the new MCF-EVOH-SP material was experimentally determined by frontal analysis using pure protein solutions in a standard liquid chromatography instrument for a range of superficial flow velocities, u =5.5-27.7cms . The mean dynamic binding capacity for hen-egg lysozyme was found to be approximately 100μg for a 5m length film, giving a ligand binding density of 413ngcm . The dynamic binding capacity did not vary significantly over the range of u tested. The application of this novel material to subtractive chromatography was demonstrated for anionic BSA and cationic lysozyme at pH 7.2. The chromatographic separation of two cationic proteins, lysozyme and cytochrome-c, was also performed with a view to applying this technology to the analysis or purification of proteins. Future applications might include separation based on anion exchange and other modes of adsorption. © 2011 Elsevier B.V

Energy-water-food nexus in the Spanish greenhouse tomato production

The nexus energy–water–food of the tomato greenhouse production in the Almeria region (Spain) has been studied following a Process Systems Analysis Method connecting the ecosystem services to the market demands with a holistic view based on Life Cycle Assessment. The management of the agri-food subsystem, the industrial subsystem and the urban subsystem plays an important role in the nexus of the E–W–F system, where transport and information technologies connect the three subsystems to the global markets. The local case study of the tomato production in Almeria (Spain) has been developed as an example of the food production under cropland restrictions, semiarid land. After study of the economic and social sustainability in time, the evolution of the ecosystem services supply is the main restriction of the system, where after the land use change in the region, water and energy supply play the mean role with a trade-off between the water quality degradation and the economic cost of the energy for water desalination. Water footprint, Carbon footprint and Chemicals footprint are useful indicators to the environmental sustainability assessment of local alternatives in the E–W–F system under study. As it is shown in the conclusions, the holistic view based on the process analysis method and the life cycle assessment methodology and indicators is an useful tool for decision support

Nanostructured Zeolites: The Introduction of Intracrystalline Mesoporosity in Basic Faujasite-Type Catalysts

A combination of postsynthesis modifications and ion exchange aiming to obtain basic cation-rich hierarchical zeolites X and Y was utilized in this work for the preparation of catalysts for biofuel production from vegetable oils. The secondary mesopore system with a narrow pore size distribution in the 4 nm range was introduced by successive acid and base treatments accompanied by surfactant templating. This was followed by ion exchange with Cs+ and K+ cations to produce strong basic catalysts. The prepared hierarchical zeolites were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, Fourier transform infrared spectroscopy, and solid-state NMR. The transesterification reaction over the zeolite catalysts was performed in a microwave batch-type reactor, and the effects of the reaction conditions, basic properties, and pore structure of the hierarchical faujasites were studied in detail. The conversion of triglycerides increased with increasing concentration of Cs and K in modified zeolites but declined with decreasing framework aluminum content. The balance between the strength of the basic sites and their accessibility in hierarchical zeolites and its effect on the catalytic performance of these nanostructured materials is discussed

Human Salmonella Typhi exposure generates differential multifunctional cross‐reactive T‐cell memory responses against Salmonella Paratyphi and invasive nontyphoidal Salmonella

Objective There are no vaccines for most of the major invasive Salmonella strains causing severe infection in humans. We evaluated the specificity of adaptive T memory cell responses generated after Salmonella Typhi exposure in humans against other major invasive Salmonella strains sharing capacity for dissemination. Methods T memory cells from eleven volunteers who underwent controlled oral challenge with wt S. Typhi were characterised by flow cytometry for cross‐reactive cellular cytokine/chemokine effector responses or evidence of degranulation upon stimulation with autologous B‐lymphoblastoid cells infected with either S. Typhi, Salmonella Paratyphi A (PA), S. Paratyphi B (PB) or an invasive nontyphoidal Salmonella strain of the S. Typhimurium serovar (iNTSTy). Results Blood T‐cell effector memory (TEM) responses after exposure to S. Typhi in humans evolve late, peaking weeks after infection in most volunteers. Induced multifunctional CD4+ Th1 and CD8+ TEM cells elicited after S. Typhi challenge were cross‐reactive with PA, PB and iNTSTy. The magnitude of multifunctional CD4+ TEM cell responses to S. Typhi correlated with induction of cross‐reactive multifunctional CD8+ TEM cells against PA, PB and iNTSTy. Highly multifunctional subsets and T central memory and T effector memory cells that re‐express CD45 (TEMRA) demonstrated less heterologous T‐cell cross‐reactivity, and multifunctional Th17 elicited after S. Typhi challenge was not cross‐reactive against other invasive Salmonella. Conclusion Gaps in cross‐reactive immune effector functions in human T‐cell memory compartments were highly dependent on invasive Salmonella strain, underscoring the importance of strain‐dependent vaccination in the design of T‐cell‐based vaccines for invasive Salmonella

Treatment of enteric fever (typhoid and paratyphoid fever) with cephalosporins

Background Typhoid and paratyphoid (enteric fever) are febrile bacterial illnesses common in many low‐ and middle‐income countries. The World Health Organization (WHO) currently recommends treatment with azithromycin, ciprofloxacin, or ceftriaxone due to widespread resistance to older, first‐line antimicrobials. Resistance patterns vary in different locations and are changing over time. Fluoroquinolone resistance in South Asia often precludes the use of ciprofloxacin. Extensively drug‐resistant strains of enteric fever have emerged in Pakistan. In some areas of the world, susceptibility to old first‐line antimicrobials, such as chloramphenicol, has re‐appeared. A Cochrane Review of the use of fluoroquinolones and azithromycin in the treatment of enteric fever has previously been undertaken, but the use of cephalosporins has not been systematically investigated and the optimal choice of drug and duration of treatment are uncertain. Objectives To evaluate the effectiveness of cephalosporins for treating enteric fever in children and adults compared to other antimicrobials. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE, Embase, LILACS, the WHO ICTRP and ClinicalTrials.gov up to 24 November 2021. We also searched reference lists of included trials, contacted researchers working in the field, and contacted relevant organizations. Selection criteria We included randomized controlled trials (RCTs) in adults and children with enteric fever that compared a cephalosporin to another antimicrobial, a different cephalosporin, or a different treatment duration of the intervention cephalosporin. Enteric fever was diagnosed on the basis of blood culture, bone marrow culture, or molecular tests. Data collection and analysis We used standard Cochrane methods. Our primary outcomes were clinical failure, microbiological failure and relapse. Our secondary outcomes were time to defervescence, duration of hospital admission, convalescent faecal carriage, and adverse effects. We used the GRADE approach to assess certainty of evidence for each outcome. Main results We included 27 RCTs with 2231 total participants published between 1986 and 2016 across Africa, Asia, Europe, the Middle East and the Caribbean, with comparisons between cephalosporins and other antimicrobials used for the treatment of enteric fever in children and adults. The main comparisons are between antimicrobials in most common clinical use, namely cephalosporins compared to a fluoroquinolone and cephalosporins compared to azithromycin. Cephalosporin (cefixime) versus fluoroquinolones Clinical failure, microbiological failure and relapse may be increased in patients treated with cefixime compared to fluoroquinolones in three small trials published over 14 years ago: clinical failure (risk ratio (RR) 13.39, 95% confidence interval (CI) 3.24 to 55.39; 2 trials, 240 participants; low‐certainty evidence); microbiological failure (RR 4.07, 95% CI 0.46 to 36.41; 2 trials, 240 participants; low‐certainty evidence); relapse (RR 4.45, 95% CI 1.11 to 17.84; 2 trials, 220 participants; low‐certainty evidence). Time to defervescence in participants treated with cefixime may be longer compared to participants treated with fluoroquinolones (mean difference (MD) 1.74 days, 95% CI 0.50 to 2.98, 3 trials, 425 participants; low‐certainty evidence). Cephalosporin (ceftriaxone) versus azithromycin Ceftriaxone may result in a decrease in clinical failure compared to azithromycin, and it is unclear whether ceftriaxone has an effect on microbiological failure compared to azithromycin in two small trials published over 18 years ago and in one more recent trial, all conducted in participants under 18 years of age: clinical failure (RR 0.42, 95% CI 0.11 to 1.57; 3 trials, 196 participants; low‐certainty evidence); microbiological failure (RR 1.95, 95% CI 0.36 to 10.64, 3 trials, 196 participants; very low‐certainty evidence). It is unclear whether ceftriaxone increases or decreases relapse compared to azithromycin (RR 10.05, 95% CI 1.93 to 52.38; 3 trials, 185 participants; very low‐certainty evidence). Time to defervescence in participants treated with ceftriaxone may be shorter compared to participants treated with azithromycin (mean difference of −0.52 days, 95% CI −0.91 to −0.12; 3 trials, 196 participants; low‐certainty evidence). Cephalosporin (ceftriaxone) versus fluoroquinolones It is unclear whether ceftriaxone has an effect on clinical failure, microbiological failure, relapse, and time to defervescence compared to fluoroquinolones in three trials published over 28 years ago and two more recent trials: clinical failure (RR 3.77, 95% CI 0.72 to 19.81; 4 trials, 359 participants; very low‐certainty evidence); microbiological failure (RR 1.65, 95% CI 0.40 to 6.83; 3 trials, 316 participants; very low‐certainty evidence); relapse (RR 0.95, 95% CI 0.31 to 2.92; 3 trials, 297 participants; very low‐certainty evidence) and time to defervescence (MD 2.73 days, 95% CI −0.37 to 5.84; 3 trials, 285 participants; very low‐certainty evidence). It is unclear whether ceftriaxone decreases convalescent faecal carriage compared to the fluoroquinolone gatifloxacin (RR 0.18, 95% CI 0.01 to 3.72; 1 trial, 73 participants; very low‐certainty evidence) and length of hospital stay may be longer in participants treated with ceftriaxone compared to participants treated with the fluoroquinolone ofloxacin (mean of 12 days (range 7 to 23 days) in the ceftriaxone group compared to a mean of 9 days (range 6 to 13 days) in the ofloxacin group; 1 trial, 47 participants; low‐certainty evidence). Authors' conclusions Based on very low‐ to low‐certainty evidence, ceftriaxone is an effective treatment for adults and children with enteric fever, with few adverse effects. Trials suggest that there may be no difference in the performance of ceftriaxone compared with azithromycin, fluoroquinolones, or chloramphenicol. Cefixime can also be used for treatment of enteric fever but may not perform as well as fluoroquinolones. We are unable to draw firm general conclusions on comparative contemporary effectiveness given that most trials were small and conducted over 20 years previously. Clinicians need to take into account current, local resistance patterns in addition to route of administration when choosing an antimicrobial

Enhanced methane reforming activity of a hydrothermally synthesised co-doped perovskite catalyst

A catalyst for the direct reforming of methane and simulated biogas has been prepared using a green and low temperature hydrothermal method. The nickel and iron co-doped SrZrO3 perovskite shows catalytic activity comparable to 10% Ni/Al2O3, but with an almost 50% saving in nickel content and a significant reduction in unwanted carbon deposition through thermal decomposition of methane and the Boudouard reaction. The use of a catalyst with a low active metal content produced via a hydrothermal route provides an attractive and sustainable method of production of synthesis gas from both methane and biogas for potential use in solid oxide fuel cells

Mucosal-Associated Invariant T cells exhibit distinct functional signatures associated with protection against typhoid fever

We have previously demonstrated that Mucosal-Associated Invariant T (MAIT) cells secrete multiple cytokines after exposure to Salmonella enterica serovar Typhi (S. Typhi), the causative agent of typhoid fever in humans. However, whether cytokine secreting MAIT cells can enhance or attenuate the clinical severity of bacterial infections remain debatable. This study characterizes human MAIT cell functions in subjects participating in a wild-type S. Typhi human challenge model. Here, we found that MAIT cells exhibit distinct functional signatures associated with protection against typhoid fever. We also observed that the cytokine patterns of MAIT cell responses, rather than the average number of cytokines expressed, are more predictive of typhoid fever outcomes. These results might enable us to objectively, based on functional parameters, identify cytokine patterns that may serve as predictive biomarkers during natural infection and vaccination