Reactive Carbon Capture Enables CO2 Electrolysis with Liquid Feedstocks.

ConspectusThe electrochemical reduction of carbon dioxide (CO2RR) is a promising strategy for mitigating global CO2 emissions while simultaneously yielding valuable chemicals and fuels, such as CO, HCOO-, and C2H4. This approach becomes especially appealing when integrated with surplus renewable electricity, as the ensuing production of fuels could facilitate the closure of the carbon cycle. Despite these advantages, the realization of industrial-scale electrolyzers fed with CO2 will be challenged by the substantial energy inputs required to isolate, pressurize, and purify CO2 prior to electrolysis.To address these challenges, we devised an electrolyzer capable of directly converting reactive carbon solutions (e.g., a bicarbonate-rich eluent that exits a carbon capture unit) into higher value products. This "reactive carbon electrolyzer" operates by reacting (bi)carbonate with acid generated within the electrolyzer to produce CO2 in situ, thereby facilitating CO2RR at the cathode. This approach eliminates the need for expensive CO2 recovery and compression steps, as the electrolyzer can then then coupled directly to the CO2 capture unit.This Account outlines our endeavors in developing this type of electrolyzer, focusing on the design and implementation of materials for electrocatalytic (bi)carbonate conversion. We highlight the necessity for a permeable cathode that allows the efficient transport of (bi)carbonate ions while maintaining a sufficiently high catalytic surface area. We address the importance of the supporting electrolyte, detailing how (bi)carbonate concentration, counter cations, and ionic impurities impact selectivity for products formed in the electrolyzer. We also catalog state-of-the-art performance metrics for reactive carbon electrolyzers (i.e., Faradaic efficiency, full cell voltage, CO2 utilization efficiency) and outline strategies to bridge the gap between these values and those required for commercial operation Collectively, these findings contribute to the ongoing efforts to realize industrial-scale electrochemical reactors for CO2 conversion, bringing us closer to a sustainable and closed-loop carbon cycle.

Oxygen-Resistant CO2 Reduction Enabled by Electrolysis of Liquid Feedstocks.

Electrolytic CO2 reduction fails in the presence of O2. This failure occurs because the reduction of O2 is thermodynamically favored over the reduction of CO2. Consequently, O2 must be removed from the CO2 feed prior to entering an electrolyzer, which is expensive. Here, we show that the use of liquid bicarbonate feedstocks (e.g., aqueous 3.0 M KHCO3), rather than gaseous CO2 feedstocks, enables efficient and selective CO2 reduction without additional procedures for removing O2. This effect is made possible because liquid bicarbonate solutions, which serve as a liquid CO2 carrier, deliver high concentrations of captured CO2 to the cathode, while the low solubility of O2 in aqueous media maintains a low O2 concentration at the same cathode surface. Consequently, electrolyzers fed with liquid bicarbonate feedstocks create an environment at the cathode that favors the reduction of CO2 over O2. We validate this claim by electrochemically converting CO2 into CO with reaction selectivities of 65% at 100 mA cm-2 using a 3.0 M KHCO3 solution bubbled with 100% CO2 or 100% O2. Similar experiments performed with a gaseous CO2 feedstock showed that merely 0.5% of O2 in the feedstock reduced CO selectivity by >90% after 1 h of electrolysis. Our findings demonstrate that a liquid bicarbonate feedstock enables efficient CO2 reduction without the need for expensive O2 removal steps.

COVID-19: smoke testing of surgical mask and respirators.

BACKGROUND: Fluid Resistant Surgical Masks have been implemented in UK personal protective equipment (PPE) guidelines for COVID-19 for all care sites that do not include aerosol-generating procedures (AGPs). FFP3 masks are used in AGP areas. Concerns from the ENT and plastic surgery communities out with intensive care units have questioned this policy. Emerging evidence on cough clouds and health care worker deaths has suggested that a review is required. AIMS: To test the efficacy of Fluid Resistant Surgical Mask with and without adaptions for respiratory protection. To test the efficacy of FFP and FFP3 regarding fit testing and usage. METHODS: A smoke chamber test of 5 min to model an 8-h working shift of exposure while wearing UK guideline PPE using an inspiratory breathing mouthpiece under the mask. Photographic data were used for comparison. RESULTS: The Fluid Resistant Surgical Mask gave no protection to inhaled smoke particles. Modifications with tape and three mask layers gave slight benefit but were not considered practical. FFP3 gave complete protection to inhaled smoke but strap tension needs to be 'just right' to prevent facial trauma. Facial barrier creams are an infection risk. CONCLUSIONS: Surgical masks give no protection to respirable particles. Emerging evidence on cough clouds and health care worker deaths suggests the implementation of a precautionary policy of FFP3 for all locations exposed to symptomatic or diagnosed COVID-19 patients. PPE fit testing and usage policy need to improve to include daily buddy checks for FFP3 users.

A 1 MA, variable risetime pulse generator for high energy density plasma research.

COBRA is a 0.5 Omega pulse generator driving loads of order 10 nH inductance to >1 MA current. The design is based on independently timed, laser-triggered switching of four water pulse-forming lines whose outputs are added in parallel to drive the load current pulse. The detailed design and operation of the switching to give a wide variety of current pulse shapes and rise times from 95 to 230 ns is described. The design and operation of a simple inductive load voltage monitor are described which allows good accounting of load impedance and energy dissipation. A method of eliminating gas bubbles on the underside of nearly horizontal insulator surfaces in water was required for reliable operation of COBRA; a novel and effective solution to this problem is described.

Thiolactomycin and related analogues as novel anti-mycobacterial agents targeting KasA and KasB condensing enzymes in Mycobacterium tuberculosis.

Prevention efforts and control of tuberculosis are seriously hampered by the appearance of multidrug-resistant strains of Mycobacterium tuberculosis, dictating new approaches to the treatment of the disease. Thiolactomycin (TLM) is a unique thiolactone that has been shown to exhibit anti-mycobacterial activity by specifically inhibiting fatty acid and mycolic acid biosynthesis. In this study, we present evidence that TLM targets two beta-ketoacyl-acyl-carrier protein synthases, KasA and KasB, consistent with the fact that both enzymes belong to the fatty-acid synthase type II system involved in fatty acid and mycolic acid biosynthesis. Overexpression of KasA, KasB, and KasAB in Mycobacterium bovis BCG increased in vivo and in vitro resistance against TLM. In addition, a multidrug-resistant clinical isolate was also found to be highly sensitive to TLM, indicating promise in counteracting multidrug-resistant strains of M. tuberculosis. The design and synthesis of several TLM derivatives have led to compounds more potent both in vitro against fatty acid and mycolic acid biosynthesis and in vivo against M. tuberculosis. Finally, a three-dimensional structural model of KasA has also been generated to improve understanding of the catalytic site of mycobacterial Kas proteins and to provide a more rational approach to the design of new drugs.

Antimycobacterial activities of isoxyl and new derivatives through the inhibition of mycolic acid synthesis.

Isoxyl (ISO), a thiourea (thiocarlide; 4, 4'-diisoamyloxythiocarbanilide), demonstrated potent activity against Mycobacterium tuberculosis H37Rv (MIC, 2.5 micrograms/ml), Mycobacterium bovis BCG (MIC, 0.5 microgram/ml), Mycobacterium avium (MIC, 2.0 microgram/ml), and Mycobacterium aurum A+ (MIC, 2.0 microgram/ml), resulting in complete inhibition of mycobacteria grown on solid media. Importantly, a panel of clinical isolates of M. tuberculosis from different geographical areas with various drug resistance patterns were all sensitive to ISO in the range of 1 to 10 microgram/ml. In a murine macrophage model, ISO exhibited bactericidal killing of viable intracellular M. tuberculosis in a dose-dependent manner (0.05 to 2.50 microgram/ml). The selective action of ISO on mycolic acid synthesis was studied through the use of [1, 2-14C]acetate labeling of M. tuberculosis H37Rv, M. bovis BCG, and M. aurum A+. At its MIC for M. tuberculosis, ISO inhibited the synthesis of both fatty acids and mycolic acids (alpha-mycolates by 91.6%, methoxymycolates by 94.3%, and ketomycolates by 91.1%); at its MIC in M. bovis BCG, ISO inhibited the synthesis of alpha-mycolates by 87.2% and that of ketomycolates by 88.5%; and the corresponding inhibitions for M. aurum A+ were 87.1% for alpha-mycolates, 87.2% for ketomycolates, and 86.5% for the wax-ester mycolates. A comparison with isoniazid (INH) and ethionamide (ETH) demonstrated marked similarity in action, i.e., inhibition of the synthesis of all kinds of mycolic acids. However, unlike INH and ETH, ISO also inhibited the synthesis of shorter-chain fatty acids. ISO showed no acute toxicity against primary macrophage cell cultures as demonstrated by diminution of redox activity. A homologous series of ISO derivatives were synthesized. Most derivatives were as effective or more effective than the parent compound in the agar proportion assay. Thus, these thioureas, like INH and ETH, specifically inhibit mycolic acid synthesis and show promise in counteracting a wide variety of drug-sensitive and -resistant strains of M. tuberculosis.

Influenza diagnosis: from dark isolation into the molecular light. West of Scotland Respiratory Virus Study Group.

OBJECTIVES: To compare the conventional virus isolation method for diagnosis of influenza infection with reverse-transcription polymerase chain reaction (RT-PCR) in prospectively collected nose and throat swabs from elderly patients during the winter influenza season. The use of a denaturing buffer as an alternative to viral transport medium (VTM) for submission of combined nose and throat swabs to the laboratory for PCR was then investigated in a second study. METHODS: Virus was cultured in microtitre plates using two different cell lines and detected using monoclonal antibody staining. A multiplex, matrix gene PCR assay was optimized to increase the sensitivity and specificity of detection of influenza A (H3 and H1) and B nucleic acid. RESULTS: The multiplex assay detected all viruses with equal sensitivity to individual assays. In a large, multicentre field study PCR detected twice as many influenza infections compared with virus isolation. No positive culture was missed. PCR has a rapid turn around time (< 36 h) vs. a minimum of 7 days for virus isolation. Greater sensitivity and specificity in the PCR were achieved using a 'hot-start' method. Although the numbers were small, the detection rate using PCR was greater for swabs submitted in denaturing buffer than in VTM. CONCLUSIONS: PCR significantly increased the sensitivity and clinical utility of influenza A (H3 and H1) and B diagnosis. There were a number of advantages in using denaturing buffer for submission of samples, including high sensitivity, rapidity, ease of use and no requirement for the virus to be viable on arrival at the laboratory. Therefore, PCR is a rapid, sensitive and user-friendly alternative for influenza diagnosis. Virus isolation technology should be limited to referral centres for further epidemiological characterization.

Novel C-2 substituted carbapenem derivatives. Part IV. Synthesis and biological activity of five membered heteroaromatic derivatives.

The synthesis, antibacterial activity, and stability to human dehydropeptidase-1 (DHP-1) of a novel series of (5R,6S)-6-[(1R)-1-hydroxyethyl]-2-heterocyclylcarbapen-2-em-3-carb oxylates are described. Of the compounds investigated 1,5-disubstituted pyrazol-3-yl and 3-substituted isoxazol-5-yl derivatives have the best combination of antibacterial activity and stability to DHP-1. They are particularly active against community-acquired respiratory tract pathogens and have stabilities to DHP-1 superior to that of meropenem.

Novel C-2 substituted carbapenem derivatives. Part II. Synthesis and structure-activity relationships of isoxazolin-2-yl, isoxazolidin-2-yl and 2-pyrazolin-2-yl carbapenems generated using 1,3-dipolar cycloaddition chemistry.

A series of carbapenems containing novel C-2 semisaturated heterocyclic substituents were synthesised by 1,3 dipolar cycloaddition reactions of nitrile oxides, nitrile imines and a nitrone to 2-vinylcarbapenem. The isoxazoline and isoxazolidine compounds showed potent antibacterial activity but moderate stability to human dehydropeptidase 1 (DHP-1). Stability to DHP-1 was improved by methyl substitution in the isoxazoline ring, but at the expense of antibacterial activity. The pyrazolines exhibited excellent stability to DHP-1, but reduced potency against Gram-negative organisms.

Occupational asthma caused by automated salmon processing.

Within 3 months of the opening of a salmon-processing plant in the UK, some workers complained of symptoms suggestive of occupational asthma. A survey of all 291 employees identified 24 (8.2%) with occupational asthma. The employees worked near machines which generated respirable aerosols containing salmon-serum proteins. The IgE response to these proteins was associated with occupational asthma (p < 0.001), with increasing severity of symptoms (p < 0.001), and with working distance from the aerosol source (p = 0.037). The main factor which predisposed to IgE-antibody production and asthma was cigarette smoking (p < 0.001), whereas atopy and a previous allergic history did not. The affected employees were reallocated to a low-exposure worksite and factory ventilation was improved. Eleven showed significant clinical and pulmonary function improvement, and continued in employment. Thirteen who still had symptoms were advised to leave, thereafter becoming symptom-free, and regaining normal respiratory function. Early recognition of symptoms and prompt action to reduce aerosol exposure avoided the long-term reduction in pulmonary functions often associated with occupational asthma.

Transcranial Doppler ultrasound in commercial air divers: a field study including cases with right-to-left shunting.

Many cases of decompression illness occur in divers using recommended decompression tables. Doppler ultrasound has been used for over 20 yr and has shown the presence of venous bubbles in asymptomatic divers working well within decompression limits. Previous studies have demonstrated an increased prevalence of patent foramen ovale in divers who have suffered neurologic decompression illness. It has been postulated that right-to-left shunting through a patent foramen ovale could allow arterialization of these bubbles, causing symptoms and signs of acute decompression illness and possibly chronic subclinical neurologic impairment. We set out to determine the incidence of bubbles in the cerebral circulation of commercial divers decompressing from air dives. Using transcranial Doppler ultrasound (TCD), the middle cerebral arteries of 17 divers were monitored after surfacing from depths ranging between 3 and 50 m. Peripheral contrast injection with simultaneous transthoracic echocardiography and TCD was used to screen for right-to-left shunting. Right-to-left shunting was detected in four divers by TCD (one at rest, two after a Valsalva maneuver, and one only after coughing); however, echocardiography was positive in only one of these subjects after a Valsalva maneuver (TCD was positive at rest in this subject). Seventy-three TCD recordings were performed in four settings: 41 after underwater decompression, 18 after surface decompression, 10 in the interval between surfacing and entering the decompression chamber, and 4 after a chamber dive. Twenty-three of these recordings were in four subjects with right-to-left shunting; no bubbles were detected in any of these recordings.(ABSTRACT TRUNCATED AT 250 WORDS)

Salmon farming: occupational health in a new rural industry.

The medical hazards of salmon farming can be grouped into those related to marine safety, fish husbandry, fish-farm diving and disease treatments. The hostile water environment requires thermal protection and personal buoyancy aids as workers frequently fall in the water from boats or cages. Feedstuffs may generate respirable dust and attract rats, creating a risk of leptospirosis. Musculo-skeletal injuries are common from lifting nets. Fish-farm diving has particular risks which can be minimized. Organophosphorous pesticides are used to treat sea lice and employees require health surveillance. Fish immunization is required to reduce the incidence of Aeromonas salmonitica. Needlestick injuries when using oil-based vaccines are a serious hazard to employees. The occupational health problems of salmon farming are predictable and preventable with primary safety measures. This new industry is safer than land-based agriculture on current evidence.

Deviance in the practice of science.

The author discusses misconduct in biomedical research in terms of research about deviance. The ancient mantle of the sacred was transferred in the late nineteenth and early twentieth century from religious institutions to the scientists and the universities that they came to dominate. Universities were engaged in the pursuit of truth; and when science came to dominate universities, they became the hallowed ground of science. Many younger scientists consider that theirs is professional work like any other, but the general public, journalists, and policymakers still consider that scientists who break the rules are guilty of heinous offenses (violations of a sacred trust). This explains in part the different reactions of scientists and the public to recent scandals involving medical researchers. One of the most important points about deviance among scientists is the need to distinguish between rules imposed on the actor and rules that the individual is personally committed to. As government funding has come to dominate biomedical research, scientists have become part of huge bureaucratic entities with values, policies, and views often at variance from those of the scientific community. Increasingly, scientists find conflict between the values and mores of their community and the rules and mores of the federal and university bureaucracies that control modern science. Scientists can come to feel that they can violate the bureaucrats' rules and still be highly principled because they do not violate the values of science. The danger is that, by a process of drift, they can come to violate increasingly important, even primary, values of science.(ABSTRACT TRUNCATED AT 250 WORDS)