The origin of overpotential in lithium-mediated nitrogen reduction.

The verification of the lithium-mediated nitrogen reduction system in 2019 has led to an explosion in the literature focussing on improving the metrics of faradaic efficiency, stability, and activity. However, while the literature acknowledges the vast intrinsic overpotential for nitrogen reduction due to the reliance on in situ lithium plating, it has thus far been difficult to accurately quantify this overpotential and effectively analyse further voltage losses. In this work, we present a simple method for determining the Reversible Hydrogen Electrode (RHE) potential in the lithium-mediated nitrogen reduction system. This method allows for an investigation of the Nernst equation and reveals sources of potential losses. These are namely the solvation of the lithium ion in the electrolyte and resistive losses due to the formation of the solid electrolyte interphase. The minimum observed overpotential was achieved in a 0.6 M LiClO4, 0.5 vol% ethanol in tetrahydrofuran electrolyte. This was -3.59 ± 0.07 V vs. RHE, with a measured faradaic efficiency of 6.5 ± 0.2%. Our method allows for easy comparison between the lithium-mediated system and other nitrogen reduction paradigms, including biological and homogeneous mechanisms.

Towards the elucidation of the high oxygen electroreduction activity of PtxY: surface science and electrochemical studies of Y/Pt(111).

We have prepared an yttrium modified Pt(111) single crystal under ultra-high vacuum conditions, simulating a bulk alloy. A Pt overlayer is formed upon annealing the crystal above 800 K. The annealed structure binds CO weaker than Pt(111), with a pronounced peak at 295 K in the temperature programmed desorption of CO. When depositing a large amount of yttrium at 1173 K, a (1.88 × 1.88)R30° structure relative to Pt(111) was observed by low energy electron diffraction. Such an electron diffraction pattern could correspond to a (2 × 2)R30° structure under 6% compressive strain. This structure is in agreement with the structure of the vacancies in a Pt Kagomé layer in Pt5Y rotated 30° with respect to the bulk of the Pt(111). The Pt overlayer is relatively stable in air; however, after performing oxygen reduction activity measurements in an electrochemical cell, a thick Pt overlayer was measured by the angle resolved X-ray photoelectron spectroscopy depth profile. The activity of the annealed Y/Pt(111) for the oxygen reduction reaction was similar to that of polycrystalline Pt3Y.

Correction: The role of ion solvation in lithium mediated nitrogen reduction.

[This corrects the article DOI: 10.1039/D2TA07686A.].

The role of ion solvation in lithium mediated nitrogen reduction.

Since its verification in 2019, there have been numerous high-profile papers reporting improved efficiency of lithium-mediated electrochemical nitrogen reduction to make ammonia. However, the literature lacks any coherent investigation systematically linking bulk electrolyte properties to electrochemical performance and Solid Electrolyte Interphase (SEI) properties. In this study, we discover that the salt concentration has a remarkable effect on electrolyte stability: at concentrations of 0.6 M LiClO4 and above the electrode potential is stable for at least 12 hours at an applied current density of -2 mA cm-2 at ambient temperature and pressure. Conversely, at the lower concentrations explored in prior studies, the potential required to maintain a given N2 reduction current increased by 8 V within a period of 1 hour under the same conditions. The behaviour is linked more coordination of the salt anion and cation with increasing salt concentration in the electrolyte observed via Raman spectroscopy. Time of flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy reveal a more inorganic, and therefore more stable, SEI layer is formed with increasing salt concentration. A drop in faradaic efficiency for nitrogen reduction is seen at concentrations higher than 0.6 M LiClO4, which is attributed to a combination of a decrease in nitrogen solubility and diffusivity as well as increased SEI conductivity as measured by electrochemical impedance spectroscopy.

Survivorship of the bio-action metatarsophalangeal joint arthroplasty for hallux rigidus: 5-year follow-up.

BACKGROUND: Metatarsophalangeal joint arthroplasty is an accepted treatment for hallux rigidus. There are few reports of the long-term results of this procedure. METHODS: A series of 15 consecutive bio-action first metatarsophalangeal total joint replacements were retrospectively reviewed after a minimum follow-up of 5 years. The patients were assessed using the American Orthopaedic Foot and Ankle Society Score. Patient satisfaction and standard radiographs were also examined. RESULTS: Subjectively, just over half the patients were satisfied with the results of the surgery. Objectively, however mechanical failure of the implant was universal, as determined radiographically. DISCUSSION: Despite some success in relieving symptoms in patients, we have abandoned this procedure because of the high and increasing rate of failure, as demonstrated both clinically and radiologically.

Single step selection of cis-diamminedichloroplatinum(II) resistant mutants from a human ovarian carcinoma cell line.

We have shown that cis diamminedichloroplatinum-(II) (DDP) resistant mutants can be isolated from the human ovarian carcinoma cell line A2780 using a single-step selection protocol with DDP. DDP resistant colonies were calculated to be present at a frequency of 1.7 x 10(-6)/viable cell using a fluctuation analysis. The mutational origin of these surviving colonies is inferred by the fact that their frequency is increased by treatment of the A2780 cells with the chemical mutagen ethyl methane-sulfonate, with a maximum frequency observed after a 3-day expression time. Independently isolated clones maintain, in the absence of selection, a DDP resistant phenotype up to 7-fold more resistant than the parental A2780 cells. The resistance modifiers aphidicolin and buthionine sulfoximine have no effect on the frequency of DDP resistant mutants. Therefore neither of these drugs appears to have an effect on increasing the sensitivity of DDP resistant mutants existing in a cell population prior to DDP exposure.

The isolation and identification of cis-diamminedichloroplatinum (ii)-DNA adducts by anion-exchange HPLC and inductively coupled plasma mass-spectrometry.

The adducts produced by the reaction of cis-diamminedichloroplatinum(II) with DNA have previously been isolated and characterised. These adducts may be measured at the cellular level by immunochemical detection but the accuracy of this assay is dependent on the number of adducts per nucleotide. We have developed a novel assay for cisplatin-DNA adducts, utilising an established method in which platinated DNA is digested to form a mixture of nucleotides and adducts; these are then separated by anion exchange HPLC. The number of cisplatin-DNA adducts is determined by measurement of the platinum content of the HPLC fractions by inductively coupled plasma mass spectrometry. The assay has been validated by cochromatography of purified drug-DNA adducts whose identity has been confirmed by NMR. We describe an application of the assay, namely the measurement of in vitro removal of cisplatin-DNA adducts from calf thymus DNA by cell free extracts derived from tumour cell lines. Adduct removal is dependent on both the amount of extract protein and the duration of the reaction. Almost 70% of adducts are removed from 5mug of DNA (drug:nucleotide ratio 0.08) by 80mug of extract. Other potential applications of the assay are discussed.

Erythrocyte Fy antigen phenotyping helps differentiate so-called benign tertian malarias.

Isolated cases of malaria are increasing in frequency in nonendemic countries. Blood film examination remains a mainstay of diagnosis of these sporadic cases because immunologic and molecular methods are unavailable, expensive, and problematic. Two tertian malarial species, Plasmodium vivax and Plasmodium ovale, may appear to be similar morphologically. Plasmodium ovale infection is infrequent, and misdiagnosis of this species is common. Plasmodium vivax infection can be ruled out, however, if a patient's erythrocytes phenotype as Fy(a-b-), because these cells completely resist entry by the latter species.

Apple II program to simulate the response-time profile of non-depolarising muscle relaxants.

We have developed a BASIC program for the Apple II microcomputer which can simulate the effect (degree of paralysis) time curve obtained following bolus intravenous administrations of pancuronium. The program is based on a combined pharmacokinetic/pharmacodynamic model and has practical application to the anaesthetist under operating room conditions. Knowing the disease state of the patient and the doses and times of administration of pancuronium the microcomputer can predict the degree of paralysis which exists at any time and so assists in the timing of the next dose of relaxant and in deciding when to effect reversal.

Dentists, pills and pregnancies.

Unplanned pregnancies may occur if antibiotics are prescribed to women using the combined oral contraceptive pill. To investigate awareness of the potential for this interaction among general dental practitioners, the authors designed a cross-sectional questionnaire based study and sent it out to a random sample of GDPs in Scotland.

Food safety and residues in Australian agricultural produce.

A brief history of food safety in Australia in the context of the development of scientific knowledge is presented. Australia's food and food commodity residue and contamination surveillance and monitoring programs are outlined. Although chemical residues are perceived as a major health risk by the general community, the risk of food causing illness or death because of chemical residues is low. The major threat to human health from food is microbiological contamination, in terms of deaths, sickness and economic loss. The emerging influences in food safety are scientific and technical developments, deregulation, social and demographic factors, and the media. The risk of disruption of domestic and export markets by food safety issues is considerable. The emergence of international standards for food production and processing will enable commercial contractual arrangements to minimise the frequency of disruptive food safety incidents.

Programs for surveillance and monitoring of antibacterial residues in Australia, 1989 to 1993.

The development of a State-based confirmatory testing capability for antibiotic residues in meat in Australia has allowed the rapid feedback to producers failing to comply with antibiotic maximum residue limits. The identification of problem areas in various categories of livestock, and subsequent focused surveillance programs, has reduced the prevalence of antibacterial residues in both domestic and export meat products. Failure to observe withholding periods of antibacterial drugs after treatment is the most significant cause of non-compliance. In the period July 1991 to June 1993 the compliance rate for antibacterial residues for all species was 99.9%.

Monitoring and surveillance in abattoirs of residues of antibacterial substances--a description of programs in Australia and the USA.

Australia and the USA are major international meat exporting countries. Both countries conduct programs to monitor and survey for antibacterial residues. Australian programs use a urine screening test, whereas the US programs use tissue fluids as the test medium. The development of surveillance programs to provide rapid feedback to producers is a feature of the Australian programs. The programs in each country compare favourably with regard to numbers of animals tested, results and action taken to prevent residues. The results of the Australian programs justify the promotion of a 'clean food' image for Australian meat products with respect to antibacterial drugs.

Weekend hospitalization and additional risk of death: an analysis of inpatient data.

OBJECTIVE: To assess whether weekend admissions to hospital and/or already being an inpatient on weekend days were associated with any additional mortality risk. DESIGN: Retrospective observational survivorship study. We analysed all admissions to the English National Health Service (NHS) during the financial year 2009/10, following up all patients for 30 days after admission and accounting for risk of death associated with diagnosis, co-morbidities, admission history, age, sex, ethnicity, deprivation, seasonality, day of admission and hospital trust, including day of death as a time dependent covariate. The principal analysis was based on time to in-hospital death. PARTICIPANTS: National Health Service Hospitals in England. MAIN OUTCOME MEASURES: 30 day mortality (in or out of hospital). RESULTS: There were 14,217,640 admissions included in the principal analysis, with 187,337 in-hospital deaths reported within 30 days of admission. Admission on weekend days was associated with a considerable increase in risk of subsequent death compared with admission on weekdays, hazard ratio for Sunday versus Wednesday 1.16 (95% CI 1.14 to 1.18; P < .0001), and for Saturday versus Wednesday 1.11 (95% CI 1.09 to 1.13; P < .0001). Hospital stays on weekend days were associated with a lower risk of death than midweek days, hazard ratio for being in hospital on Sunday versus Wednesday 0.92 (95% CI 0.91 to 0.94; P < .0001), and for Saturday versus Wednesday 0.95 (95% CI 0.93 to 0.96; P < .0001). Similar findings were observed on a smaller US data set. CONCLUSIONS: Admission at the weekend is associated with increased risk of subsequent death within 30 days of admission. The likelihood of death actually occurring is less on a weekend day than on a mid-week day.