Temperature-Dependent Kinetics of the Reactions of the Criegee Intermediate CH2OO with Hydroxyketones

Though there is a growing body of literature on the kinetics of CIs with simple carbonyls, CI reactions with functionalized carbonyls such as hydroxyketones remain unexplored. In this work, the temperature-dependent kinetics of the reactions of CH2OO with two hydroxyketones, hydroxyacetone (AcOH) and 4-hydroxy-2-butanone (4H2B), have been studied using a laser flash photolysis transient absorption spectroscopy technique and complementary quantum chemistry calculations. Bimolecular rate constants were determined from CH2OO loss rates observed under pseudo-first-order conditions across the temperature range 275-335 K. Arrhenius plots were linear and yielded T-dependent bimolecular rate constants: kAcOH(T) = (4.3 ± 1.7) × 10-15 exp[(1630 ± 120)/T] and k4H2B(T) = (3.5 ± 2.6) × 10-15 exp[(1700 ± 200)/T]. Both reactions show negative temperature dependences and overall very similar rate constants. Stationary points on the reaction energy surfaces were characterized using the composite CBS-QB3 method. Transition states were identified for both 1,3-dipolar cycloaddition reactions across the carbonyl and 1,2-insertion/addition at the hydroxyl group. The free-energy barriers for the latter reaction pathways are higher by ∼4-5 kcal mol-1, and their contributions are presumed to be negligible for both AcOH and 4H2B. The cycloaddition reactions are highly exothermic and form cyclic secondary ozonides that are the typical primary products of Criegee intermediate reactions with carbonyl compounds. The reactivity of the hydroxyketones toward CH2OO appears to be similar to that of acetaldehyde, which can be rationalized by consideration of the energies of the frontier molecular orbitals involved in the cycloaddition. The CH2OO + hydroxyketone reactions are likely too slow to be of significance in the atmosphere, except at very low temperatures.

Long Term Patient Reported Quality of Life Outcomes and Patient Satisfaction of 1-Week Hypofractionated Whole Breast Radiation Therapy Using IMRT for Early-Stage Breast Cancer

PURPOSE/OBJECTIVE(S)

Novel whole breast radiation therapy (WBRT) regimens have been recently reported with the aim of improving patient convenience while preserving local control and breast cosmesis. The UK FAST Forward trial showed that 26 Gy in 5 fx using 3D conformal WBRT was equivalent to the standard 3-week regimen. However, the use of inverse planned intensity modulated radiation therapy (IMRT) for this novel ultra-hypofractionated regimen has not been previously studied. We aim to study the patient reported quality of life (QOL) outcomes and patient satisfaction of WBRT using IMRT delivering 26 Gy in 5 fractions.

MATERIALS/METHODS

Patients receiving WBRT with 26 Gy in 5 fractions using IMRT at our institution from 2020 to 2022 were included. Patients were treated with 26 Gy in 5 daily fx with or without a single fx boost of 4-5.2 Gy. IMRT plans were generated using inverse planning with 2 to 3 volumetric modulated arcs (VMAT). To assess patient-reported QOL outcomes, a questionnaire was prospectively administered at 1 month post treatment and yearly thereafter including the EORTC QLQ-BR23 breast cancer module and other patient satisfaction questions. Patient assessment involved a four-point scale (not at all, a little, quite a bit, and very much; very satisfied, moderately satisfied, moderately dissatisfied, and very dissatisfied). Here, we report the 1-year patient reported acute toxicity QOL outcomes and patient satisfaction for those undergoing IMRT based WBRT. Cross-sectional analyses were used to determine the prevalence of "quite a bit" or "very much" effects versus "not at all" or "a little" effects.

RESULTS

A total of 96 patients were included. The median age at diagnosis was 65 years. The most common histology was invasive ductal carcinoma (53.1%). ER-positivity was found in 75.5% patients. Oncoplastic reconstruction was used in 51.0% patients. The median tumor size was 1.5 cm. There were 4/98 (4.3%) node positive patients and 22.5% received adjuvant chemotherapy. Endocrine therapy was used in 74.5% patients. A boost fraction was delivered in 95.9% patients. At the 1-year assessment, only 1/35 (2.9%), 2/35 (5.7%), and 4/35 (11.4%) patients reported "quite a bit" or "very much" breast pain, skin problems, and changes in breast appearance respectively. Additionally, 32/35 (91.4%) patients were either "very satisfied" or "moderately satisfied" with their treatment, while 32/35 (91.4%) patients reported "excellent" (n = 12) or "good" (n = 20) physical appearance of the breast.

CONCLUSION

WBRT using inverse planned IMRT with 26 Gy in 5 fx shows excellent patient reported QOL and patient satisfaction at 1-year post RT. Longer follow up is needed to assess the long-term toxicity, normal tissue effects, and cosmetic outcomes of IMRT based delivery of this ultra-hypofractionated regimen.

Acetylacetone Photolysis at 280 nm Studied by Velocity-Map Ion Imaging

The photolysis of acetylacetone (AcAc) has been studied using velocity-map ion imaging with pulsed nanosecond lasers. The enolone tautomer of AcAc (CH3C(O)CH═C(OH)CH3) was excited in the strong UV absorption band by UV pulses at 280 nm, preparing the S2(ππ*) state, and products were probed after a short time delay by single-photon VUV ionization at 118.2 nm. Two-color UV + VUV time-of-flight mass spectra show enhancement of fragments at m/z = 15, 42, 43, 58, and 85 at the lowest UV pulse energies and depletion of the parent ion at m/z = 100. Ion images of the five major fragments are all isotropic, indicating dissociation lifetimes that are long on the timescale of molecular rotation but shorter than the laser pulse duration (<6 ns). The m/z = 15 and 85 fragments have identical momentum distributions with moderate translational energy release, suggesting that they are formed as a neutral product pair and likely via a Norrish type I dissociation of the enolone to form CH3 + C(O)CH═C(OH)CH3 over a barrier on a triplet surface. The m/z = 43 fragment may be tentatively assigned to the alternative Norrish type I pathway that produces CH3CO + CH2C(O)CH3 on S0 following phototautomerization to the diketone, although alternative mechanisms involving dissociative ionization of a larger primary photoproduct cannot be conclusively ruled out. The m/z = 42 and 58 fragments are not momentum-matched and consequently are not formed as a neutral pair via a unimolecular dissociation pathway on S0. They also likely originate from the dissociative ionization of primary photofragments. RRKM calculations suggest that unimolecular dissociation pathways that lead to molecular products on S0 are generally slow, implying an upper-limit lifetime of <46 ns after excitation at 280 nm. Time-dependent measurements suggest that the observed photofragments likely do not arise from dissociative ionization of energized AcAc S0*.

Fathers' Relational Experiences of Stillbirth: Pre-natal Attachment, Loss and Continuing Bonds Through Use of Objects

This study aimed to investigate fathers' lived experiences of stillbirth through the lens of continuing bonds and use of objects. Semi-structured interviews were conducted with six fathers who had experienced stillbirth from 20 weeks gestation. Interpretative phenomenological analysis revealed five themes: loss and continued bonds in a mother-mediated dynamic, objects as manifestations of relational and meaningful memories, exerting existence and continued connection to others, continued bond through physical presence and evolving expressions of love and fatherhood. Findings offer a novel understanding of the relationship between objects and continued bonds, where objects are seen to facilitate this bond through varying means, including physical manifestation of the deceased and representation of the father-infant relationship. The study places importance on fathers' involvement in creating objects permeated with meaning and memories, and of validating fathers' experiences of loss rather than considering these men merely as partners of a mother who lost their own baby.

Toward Universal Eye Health Coverage-Key Outcomes of the World Health Organization Package of Eye Care Interventions: A Systematic Review

Importance

Despite persistent inequalities in access to eye care services globally, guidance on a set of recommended, evidence-based eye care interventions to support country health care planning has not been available. To overcome this barrier, the World Health Organization (WHO) Package of Eye Care Interventions (PECI) has been developed.

Objective

To describe the key outcomes of the PECI development.

Evidence Review

A standardized stepwise approach that included the following stages: (1) selection of priority eye conditions by an expert panel after reviewing epidemiological evidence and health facility data; (2) identification of interventions and related evidence for the selected eye conditions from a systematic review of clinical practice guidelines (CPGs); stage 2 included a systematic literature search, screening of title and abstracts (excluding articles that were not relevant CPGs), full-text review to assess disclosure of conflicts of interest and affiliations, quality appraisal, and data extraction; (3) expert review of the evidence extracted in stage 2, identification of missed interventions, and agreement on the inclusion of essential interventions suitable for implementation in low- and middle-income resource settings; and (4) peer review.

Findings

Fifteen priority eye conditions were chosen. The literature search identified 3601 articles. Of these, 469 passed title and abstract screening, 151 passed full-text screening, 98 passed quality appraisal, and 87 were selected for data extraction. Little evidence (≤1 CPG identified) was available for pterygium, keratoconus, congenital eyelid disorders, vision rehabilitation, myopic macular degeneration, ptosis, entropion, and ectropion. In stage 3, domain-specific expert groups voted to include 135 interventions (57%) of a potential 235 interventions collated from stage 2. After synthesis across all interventions and eye conditions, 64 interventions (13 health promotion and education, 6 screening and prevention, 38 treatment, and 7 rehabilitation) were included in the PECI.

Conclusions and Relevance

This systematic review of CPGs for priority eye conditions, followed by an expert consensus procedure, identified 64 essential, evidence-based, eye care interventions that are required to achieve universal eye health coverage. The review identified some important gaps, including a paucity of high-quality, English-language CPGs, for several eye diseases and a dearth of evidence-based recommendations on eye health promotion and prevention within existing CPGs.

'It's a double whammy': A qualitative study of illness uncertainty in individuals with Parkinson's disease in the context of COVID-19

OBJECTIVES

The purpose of this study was to explore the experiences of individuals with Parkinson's through the theoretical lens of illness uncertainty during the first UK full lockdown period (March-June 2020) put in place due outbreak of the COVID-19 pandemic.

METHODS

Individual semi-structured interviews were carried out via telephone in May 2020 with 10 individuals with Parkinson's (six men and four women) recruited from Parkinson's UK. Interviews were recorded and transcribed verbatim, and thematic analysis was adopted to analyse the resulting data.

RESULTS

Four overarching themes emerged from the interview data: (1) COVID-19 amplifying existing fears and difficulties around the uncertainty of Parkinson's; (2) practical and psychological efforts to manage uncertainty; (3) benefit-finding as a way of acknowledging the positives of lockdown; (4) risk and future management in the context of uncertainty.

DISCUSSION

Participants reported a range of implicit and explicit strategies to cope with the 'double whammy' of uncertainty caused by having Parkinson's during a global pandemic. While these were generally successful in maintaining well-being, it is important that such successful accounts are used to help inform novel strategies and interventions targeting individuals who might need additional support.

The Nine Cancer Frames: A Tool to Facilitate Critical Reading of Cancer-Related Information

People's ability to critically assess cancer-related information is essential from a preventional and therapeutic, as well as a general democratic perspective. Such cancer literacy is not just about acquiring factual knowledge. It also involves the ability to analyze how the information is contextualized-how cancer is framed. Previous research concerning the framing of cancer in public discourse is voluminous and penetrating but also fragmented and inaccessible to non-experts. In this study, we have developed an integrated and applicable tool for analyzing cancer discourse by systematically classifying distinctive ways of framing of the concept of cancer. Building on previous research and an inductive framing analysis of a broad range of public cancer discourse, systematically selected from British and Norwegian newspapers, we have characterized nine cancer frames: the biomedical, the environmental, the epidemiological, the personal, the sociopolitical, the economic, the antagonistic, the alternative, and the symbolic frame. This framing scheme may be applied to analyze cancer-related discourse across a plurality of themes and contexts. We also show how different frames combine to produce more complex messages, thereby revealing underlying patterns, strategies, and conflicts in cancer communication. In conclusion, this analytical tool enables critical reading of cancer-related information and may be especially useful in educational initiatives to advance health communication and public understanding of cancer.

956 AN AUDIT CONDUCTED LOOKING INTO THE USE OF IV IRON TO TREAT IRON DEFICIENCY ANAEMIA ON THE ELDERLY CARE WARDS

Aims

To assess whether patients on the elderly care wards at NUH (Nottingham University Hospitals) were appropriately given IV (intravenous) iron for Iron deficiency anaemia (IDA). To improve our practice in the investigation and follow up of patients with IDA.

Method

Data was obtained of patients who had IV iron dispensed from June—September 2019. This totalled 146 patients. Digital medical records and Notis results. Server were reviewed and a spread sheet database compiled with patient demographics, presentation, blood results. Co-morbidities, medication, investigations and follow up.

Results

The average age of the patients receiving IV iron on the elderly care wards was 86 (range 74–106). 89 were female and 57 male. The top presenting complaints were; fall (38%), abdominal symptoms of pain, diarrhoea or vomiting (15%), SOB (12%). 30% of patient were on anti-coagulation and 27% were on an anti-platelet with 2% of patient on both. Mean female Hb was 89 (41–129) and male Hb was 91 (49–117). The data showed that 8 out of 81 female patients were given IV iron despite not being anaemic. In 7.5% of cases ferritin, TSAT, iron and transferrin had not been checked. Ferritin was not checked 16%. 82% of patients had no documentation with regards to the rationale for choosing not to proceed with invasive investigation.

Conclusion

Improvement is needed in the way we manage patients with IDA. This audit highlighted the need for continued review of medications—particularly anti-platelets and anti-coagulants. If there is a weak indication consider the risks and benefits. It is important we discuss and document the consideration or unsuitability of invasive investigations and follow up. A proforma is being written to guide clinicians with regards to the appropriate prescribing of IV iron and to guide investigation and follow up.

Covid-19 Epidemic Impact on Clinical Training in Irish GP Training

Aim To describe the effect of the Covid pandemic on the general practice workplace based learning of GP training in Ireland. Methods A prospective national survey of GP trainees who were in their GP practice placements on three separate occasions throughout the winter pandemic of 2020/2021 Results The average response rate to the three surveys was 19.4%. As the pandemic worsened, the number of face to face consultations dropped so that 51% (n=41) of trainees were seeing less than 5 patients face to face by the third survey. Conversely, the number of telephone/video consultations rose so that by the third survey 54% (n=44) of trainees were conducting more than 16 consultations per day remotely. Examinations and GP presentations expected to be daily occurrences diminished as the pandemic grew more severe, such that by the third survey 24-25% of trainees had not conducted a respiratory examination or dealt with new/unexpected hypertension in the previous month. Conclusion This study demonstrates abrupt change to the normal course of their training which was experienced by Irish GP trainees as a result of Covid, with examples from clinical practice. Adaptions of the training programme helped mitigate against the effects of the pandemic.

The Use of the Saccadometer to Identify Saccadic Characteristics in Myasthenia Gravis: A Pilot Study

BACKGROUND

Myasthenia gravis (MG) often presents with ocular signs that mimic other forms of ocular defects, such as isolated cranial nerve palsy. Normal velocity or even hyperfast saccadic eye movements in the presence of deficits of smooth pursuit have been well described in the literature in myasthenic patients. The reason for these paradoxical clinical findings has been reported to be due to increased postsynaptic folding of the fast-twitch fibers responsible for the execution of a saccade which is absent in those fibers responsible for slower, smooth eye movement. Saccadic characteristics therefore offer a point of differential diagnosis between patients suspected of having ocular motility deficits as a result of MG and those caused by other neuropathies. The advent of portable quantitative saccadic assessment means that previously laboratory-based assessments that require specialist equipment and training may now be undertaken clinically, providing a noninvasive test that can aid the differential diagnosis of the condition. The aim of this pilot study was to investigate the feasibility of the saccadometer (Ober Consulting, Poznan, Poland) in detecting the saccadic characteristics associated with myasthenia, specifically normal peak velocity (PV) in a group of patients confirmed with myasthenia.

METHODS

A group of 5 patients with a confirmed diagnosis of MG were recruited from a single site into the study along with 5 age-matched healthy volunteers. All myasthenic patients had ocular signs such as underaction or limitations of motility confirmed through ocular clinical examination. Healthy volunteers were screened for any underlying ocular motility or neurological defects before inclusion within the study. All participants undertook 100 trials of both 10 and 20° amplitude saccades, and mean PV, amplitude, and latency were recorded using the saccadometer for each individual. Overall, mean PV, amplitude, and latency were collated for both myasthenic and healthy control groups for each saccade size and compared.

RESULTS

The mean PV was significantly greater (481 ± 103.5 deg/seconds) for myasthenic patients compared with healthy controls (384 ± 42.8 deg/seconds) (P < 0.05) in 10° saccades. PV was also greater in myasthenics for 20° saccades; however, this difference did not reach statistical significance for patients with MG (547 ± 89.8 deg/seconds vs 477 ± 104.5 deg/seconds) (P = 0.14). The latency of participants with MG was not significantly different from those of age-matched healthy participants in 10° saccades but was significantly different for 20° saccades. There was no difference in amplitude measured between the groups.

CONCLUSIONS

PV for both 10 and 20° saccades was greater in myasthenic patients compared with healthy controls. All myasthenic patients produced normal velocity saccades in the presence of deficits of smooth ocular motility. The results from this small pilot study demonstrate the potential use of the saccadometer in a clinical setting to provide a noninvasive aid in the diagnosis of patients suspected with myasthenia.

Co-designing a training package to promote health/oral health for people experiencing homelessness

Background

In Scotland, 31,333 households were assessed as experiencing homelessness in 2019/20. This population present high morbidity and mortality which is a public health issue. Their health needs have been identified within Scottish policy as part of the broad goal of reducing inequalities and poverty. Those experiencing homelessness face multiple exclusions that must be addressed by practitioners from all health and social care sectors. Frontline staff have identified they often do not have adequate information and/or training on wider health issues linked with their client's needs. The aim of this research is to co-produce training resources to support front-line staff to discuss and to promote health and oral health.

Methods

Community-based participatory research that used online workshops to listen to the views of people with lived experience, practitioners and students from health and third sector, and policy makers regarding accessibility of services and practitioner approach towards those experiencing homelessness. Content analysis will be used to identified recurrent themes.

Results

The preliminary findings shown that lack of empathy from practitioners, continuity of care and stigma are barriers to access services. This is informing a co-designed knowledge exchange training packaged to help practitioners to improve knowledge and ability to promote health/oral health and to engage with people experiencing homelessness or at risk of becoming homeless. Educational materials (e-book on health promotion, comics books on barriers to access services, and a guide to promote oral health) compose this training package.

Conclusions

The training package allows adaptations to different settings and contexts and will be an important resource to be used by practitioners from different fields to prevent and tackle homelessness. Participants are sharing important views related to the need of a human rights and social justice-based approach to health promotion.

Key messages

Development of a co-designed knowledge exchange training package to improve practitioners' knowledge and ability to communicate and to engage with people experiencing homelessness. To empower people experiencing homelessness regarding positive health/oral health behavior change.

Kinetics of the Reactions of CH2OO with Acetone, α-Diketones, and β-Diketones

Rate constants for the reactions between the simplest Criegee intermediate, CH₂OO, with acetone, the α-diketones biacetyl and acetylpropionyl, and the β-diketones acetylacetone and 3,3-dimethyl-2,4-pentanedione have been measured at 295 K. CH₂OO was produced photochemically in a flow reactor by 355 nm laser flash photolysis of diiodomethane in the presence of excess oxygen. Time-dependent concentrations were measured using broadband transient absorption spectroscopy, and the reaction kinetics was characterized under pseudo-first-order conditions. The bimolecular rate constant for the CH₂OO + acetone reaction is measured to be (4.1 ± 0.4) × 10^-13 cm³ s^-1, consistent with previous measurements. The reactions of CH₂OO with the β-diketones acetylacetone and 3,3-dimethyl-2,5-pentanedione are found to have broadly similar rate constants of (6.6 ± 0.7) × 10^-13 and (3.5 ± 0.8) × 10^-13 cm³ s^-1, respectively; these values may be cautiously considered as upper limits. In contrast, α-diketones react significantly faster, with rate constants of (1.45 ± 0.18) × 10^-11 and (1.29 ± 0.15) × 10^-11 cm³ s^-1 measured for biacetyl and acetylpropionyl. The potential energy surfaces for these 1,3-dipolar cycloaddition reactions are characterized at the M06-2X/aug-cc-pVTZ and CBS-QB3 levels of theory and provide additional support to the observed experimental trends. The reactivity of carbonyl compounds with CH₂OO is also interpreted by application of frontier molecular orbital theory and predicted using Hammett substituent constants. Finally, the results are compared with other kinetic studies of Criegee intermediate reactions with carbonyl compounds and discussed within the context of their atmospheric relevance.

The potential impact of post-COVID symptoms in the healthcare sector

BACKGROUND

The phenomenon of post-COVID syndrome (PCS) is evolving from an abstract array of non-specific symptoms to an identifiable clinical entity of variable severity. Its frequency and persistence have implications for service delivery and workforce planning.

AIMS

This study was aimed to assess the prevalence of symptoms consistent with PCS and the subjective degree of recovery in a cohort of healthcare workers, focusing on those who have returned to work.

METHODS

A study population of 1176 was surveyed when attending for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody testing. Two sub-groups were identified: those with known (i.e. diagnosed on PCR testing) and assumed (i.e. antibody evidence of previous infection) SARs-CoV-2 infection, at least 12 weeks prior to the study. Each group was asked about their subjective degree of recovery and the nature of their persistent symptoms. Results were analysed via excel and SPSS.

RESULTS

In total, 144 employees showed PCR evidence of previous infection, with 139 of these being infected at least 12 weeks prior to the study. Of these 139, only 19% (n = 26) reported feeling 100% recovered, and 71% reported persistent symptoms. Of those with assumed SARS-CoV-2 infection (n = 78), 32 (41%) were truly asymptomatic since the commencement of the pandemic, while 46 (59%) described symptoms suggestive of possible infection at least 12 weeks prior to the study. Of this latter group, 23% (n = 18) also reported residual symptoms.

CONCLUSIONS

PCS is prevalent among this group, including those not previously diagnosed with COVID-19. Its' frequency and duration present challenges to employers with regards to the management of work availability and performance.

Outcomes of the Harada-Ito Procedure

PURPOSE

Fell's modification of the Harada-Ito (HI) procedure is often used to tackle subjective torsion usually following superior oblique palsy. There is limited published data on the longer-term outcomes and the effect on horizontal incomitance of the procedure. The purpose of this study is to report on the medium to long-term outcomes of the HI procedure.

MATERIALS AND METHODS

A retrospective review of 20 patients who had all undergone a single surgeon modified HI procedure to correct subjective torsion was undertaken. Follow-up data were analyzed in relation to stability of torsion measurements, the effect on vertical incomitance of horizontal deviation and the final treatment outcome.

RESULTS

There was a significant reduction in median maximum torsion from preoperative to immediately post-op (p < .01) and there remained a significant difference in maximum torsion from preoperative measurement at both the 3-month (p = .02), and 12-twelve month (p = .01) follow-up. HI had a significant effect on associated V-pattern esotropia (p < .05).

CONCLUSION

The HI procedure is effective in eliminating subjective torsion initially and reducing incomitant horizontal deviation; however, regression toward preoperative torsion measurement occurs after time.

Bridging the age gap in breast cancer: cluster randomized trial of two decision support interventions for older women with operable breast cancer on quality of life, survival, decision quality, and treatment choices

BACKGROUND

Rates of surgery and adjuvant therapy for breast cancer vary widely between breast units. This may contribute to differences in survival. This cluster RCT evaluated the impact of decision support interventions (DESIs) for older women with breast cancer, to ascertain whether DESIs influenced quality of life, survival, decision quality, and treatment choice.

METHODS

A multicentre cluster RCT compared the use of two DESIs against usual care in treatment decision-making in older women (aged at least ≥70 years) with breast cancer. Each DESI comprised an online algorithm, booklet, and brief decision aid to inform choices between surgery plus adjuvant endocrine therapy versus primary endocrine therapy, and adjuvant chemotherapy versus no chemotherapy. The primary outcome was quality of life. Secondary outcomes included decision quality measures, survival, and treatment choice.

RESULTS

A total of 46 breast units were randomized (21 intervention, 25 usual care), recruiting 1339 women (670 intervention, 669 usual care). There was no significant difference in global quality of life at 6 months after the baseline assessment on intention-to-treat analysis (difference -0.20, 95 per cent confidence interval (C.I.) -2.69 to 2.29; P = 0.900). In women offered a choice of primary endocrine therapy versus surgery plus endocrine therapy, knowledge about treatments was greater in the intervention arm (94 versus 74 per cent; P = 0.003). Treatment choice was altered, with a primary endocrine therapy rate among women with oestrogen receptor-positive disease of 21.0 per cent in the intervention versus 15.4 per cent in usual-care sites (difference 5.5 (95 per cent C.I. 1.1 to 10.0) per cent; P = 0.029). The chemotherapy rate was 10.3 per cent at intervention versus 14.8 per cent at usual-care sites (difference -4.5 (C.I. -8.0 to 0) per cent; P = 0.013). Survival was similar in both arms.

CONCLUSION

The use of DESIs in older women increases knowledge of breast cancer treatment options, facilitates shared decision-making, and alters treatment selection. Trial registration numbers: EudraCT 2015-004220-61 (https://eudract.ema.europa.eu/), ISRCTN46099296 (http://www.controlled-trials.com).

Multidisciplinary management of locally advanced and metastatic cutaneous squamous cell carcinoma

Non-melanoma skin cancers are the most prevalent form of cancer, with cutaneous squamous cell carcinoma (cscc) being the 2nd most common type. Patients presenting with high-risk lesions associated with locally advanced or metastatic cscc face high rates of recurrence and mortality. Accurate staging and risk stratification for patients can be challenging because no system is universally accepted, and no Canadian guidelines currently exist. Patients with advanced cscc are often deemed ineligible for either or both of curative surgery and radiation therapy (rt) and, until recently, were limited to off-label systemic cisplatin-fluorouracil or cetuximab therapy, which offers modest clinical benefits and potentially severe toxicity. A new systemic therapy, cemiplimab, has been approved for the treatment of locally advanced and metastatic cscc. In the present review, we provide recommendations for patient classification and staging based on current guidelines, direction for determining patient eligibility for surgery and rt, and an overview of the available systemic treatment options for advanced cscc and of the benefits of a multidisciplinary approach to patient management.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Mode-specific vibrational predissociation dynamics of (HCl)2 via the free and bound HCl stretch overtones

Velocity-map ion imaging has been used to study the vibrational predissociation dynamics of the HCl dimer following infrared (IR) excitation in the HCl stretch overtone region near 1.77 Å. HCl monomer predissociation products were detected state-selectively using 2 + 1 resonance-enhanced multiphoton ionization spectroscopy. The IR action spectrum shows the free HCl stretch (2ν₁), the bound HCl stretch (2ν₂), and a combination band involving the intermolecular van der Waals stretching mode (2ν₂ + ν₄). Fragment speed distributions extracted from ion images obtained for a range of HCl(v = 0, 1; J) levels following vibrational excitation on the 2ν₁ and 2ν₂ bands yield the correlated product pair distributions. All product pairs comprise HCl(v = 1) + HCl(v = 0) and show a strong propensity to minimize the recoil kinetic energy. Highly non-statistical and mode-dependent HCl product rotational distributions are observed, in contrast to that observed following stretch fundamental excitation. Predissociation lifetimes are also mode-dependent: excitation of the free HCl leads to τ_VP = 13 ± 1 ns, while the bound stretch has a shorter lifetime τ_VP ≤ 6 ns. The dimer dissociation energy determined from energy conservation (D₀ = 397 ± 7 cm^-1) is slightly smaller than the previously reported values. The results are discussed in the context of previous observations for (HF)₂ and (HCl)₂ after excitation of HX stretch fundamentals and models for vibrational predissociation.

Synthesis and Magnetic Properties of a Copper Cube: [Cu4(OH)4(C16H18N2)4]4+ (ClO4)4 C3H6O [C16H18N2=(E)-1,6-[Di(pyridin-4-yl)hex-3-ene]

The synthesis of a Cu4(OH)4 cube which is coordinated by four molecules of the dipyridyl ligand 1,6-[di(pyridin-4-yl)hex-3-ene] is reported. This compound has a trans double bond which restricts the conformational freedom of the ligand and favours coordination within a unique copper cube. The structure was solved by an X-Ray single crystal structure determination and low temperature magnetic susceptibility measurements examined its magnetic properties. The cube classification corresponds to the type I classification of Mergehenn and Haase and the short/long distribution of Cu ⋅⋅⋅ Cu separations in the cube as defined by Ruiz. The magnetic susceptibility measurements show paramagnetic behaviour down to 50 K but below this the copper cube shows weak ferromagnetic exchange interactions. The low temperature magnetic susceptibility characteristics are examined in detail then modelled and compared to other similar Cu4O4 copper cubes.

Primary excision margins, sentinel lymph node biopsy, and completion lymph node dissection in cutaneous melanoma: a clinical practice guideline

Background

For patients who are diagnosed with early-stage cutaneous melanoma, the principal therapy is wide surgical excision of the primary tumour and assessment of lymph nodes. The purpose of the present guideline was to update the 2010 Cancer Care Ontario guideline on wide local excision margins and sentinel lymph node biopsy (slnb), including treatment of the positive sentinel node, for melanomas of the trunk, extremities, and head and neck.

Methods

Using Ovid, the medline and embase electronic databases were systematically searched for systematic reviews and primary literature evaluating narrow compared with wide excision margins and the use of slnb for melanoma of the truck and extremities and of the head and neck. Search timelines ran from 2010 through week 25 of 2017.

Results

Four systematic reviews were chosen for inclusion in the evidence base. Where systematic reviews were available, the search of the primary literature was conducted starting from the end date of the search in the reviews. Where systematic reviews were absent, the search for primary literature ran from 2010 forward. Of 1213 primary studies identified, 8 met the inclusion criteria. Two randomized controlled trials were used to inform the recommendation on completion lymph node dissection.Key updated recommendations include:■ Wide local excision margins should be 2 cm for melanomas of the trunk, extremities, and head and neck that exceed 2 mm in depth.■ slnb should be offered to patients with melanomas of the trunk, extremities, and head and neck that exceed 0.8 mm in depth.■ Patients with sentinel node metastasis should be considered for nodal observation with ultrasonography rather than for completion lymph node dissection.

Conclusions

Recommendations for primary excision margins, sentinel lymph node biopsy, and completion lymph node dissection in patients with cutaneous melanoma have been updated based on the current literature.

Primary care doctor and nurse utilisation rates for billed consultations across the Comprehensive Care Primary Health Organisation

AIM

To examine socio-demographic trends in doctor and nurse utilisation rates for invoiced consultations across Comprehensive Care Primary Health Organisation (PHO).

METHOD

De-identified enrolled patient information and Service Utilisation Reporting data for invoiced consultations were extracted from all general practices for January 2013-December 2016. Utilisation rates were calculated using the number of enrolled patients as the denominator.

RESULTS

Data for 3,657,873 invoiced consultations across 66 general practices were analysed, including 2,941,624 doctor and 716,249 nurse consultations. Average utilisation rates were 3.1 visits per patient year for doctors and 0.7 visits for nurses, with considerable variability between practices. Utilisation rates were higher for females (3.3 visits for doctors; 0.8 for nurses), older adults (5.0-6.9; 1.3-1.6 visits) and patients residing in the most socially deprived quintile (3.3; 1.6 visits). European patients had the highest doctor utilisation rates (3.2 visits), while Māori and Pacific patients had the highest nurse utilisation rates (1.1 and 1.3 visits, respectively).

CONCLUSION

Females, older adults and people residing in socially deprived areas utilise primary care more frequently according to invoiced consultation data. Analysis of all other consultations, including immunisations, Accident Corporation Claims and non-billed services is needed to more accurately capture utilisation rates, particularly for nurses, to better inform national decision-making, workforce planning and funding assumptions.

Burden of neurodegenerative diseases in the Eastern Mediterranean Region, 1990-2016: findings from the Global Burden of Disease Study 2016

BACKGROUND AND PURPOSE

The Eastern Mediterranean Region (EMR) is experiencing a demographic shift towards rapid aging at a time of political unrest. We aimed to estimate the burden of neurodegenerative disorders and its relationship with sociodemographic index in the EMR countries from 1990 to 2016.

METHODS

Using data from the Global Burden of Disease Study 2016, we calculated country-specific trends for prevalence, mortality, disability-adjusted life-years (DALY), years of life lost and years lived with disability (YLD) for Alzheimer's disease/other dementias and Parkinson's disease in the EMR during 1990-2016.

RESULTS

In the EMR, the age-standardized prevalence rate of Alzheimer's disease/other dementias and Parkinson's disease was estimated at 759.8/100 000 (95% uncertainty intervals, 642.9-899.9) and 87.1/100 000 (95% uncertainty intervals, 69.8-108.2) people in 2016, demonstrating 0.01% and 42.3% change from 1990, respectively. Neurodegenerative disorders contributed to 5.4% of total DALY and 4.6% of total YLD among the older EMR population (70 years of age or older in 2016). Age-standardized DALY due to Parkinson's disease were strongly correlated with the sociodemographic index level (r = 0.823, P < 0.001). The YLD:DALY ratio of neurodegenerative diseases declined during this period in the low-income but not the high-income EMR countries.

CONCLUSIONS

Our findings demonstrated an increasing trend in the burden of dementias and Parkinson's disease in most EMR countries between 1990 and 2016. With aging of the EMR populations, countries should target the modifiable risk factors of neurodegenerative diseases to control their increasing burden.

Racism Is Not a Factor in Door-to-electrocardiogram Times of Patients With Symptoms of Acute Coronary Syndrome: A Prospective, Observational Study

Background

Investigators have identified important racial identity/ethnicity‐based differences in some aspects of acute coronary syndrome (ACS) care and outcomes (time to presentation, symptoms, receipt of coronary angiography/revascularization, repeat revascularization, mortality). Patient‐based differences such as pathophysiology and treatment‐seeking behavior account only partly for these outcome differences. We sought to investigate whether there are racial identity/ethnicity‐based variations in the initial emergency department (ED) triage and care of patients with suspected ACS in Canadian hospitals.

Methods

We prospectively enrolled ED patients with suspected ACS from one university‐affiliated and two community hospitals. Trained research assistants administered a standardized interview to gather data on symptoms, treatment‐seeking patterns, and self‐reported racial/ethnic identity: “white,” South Asian” (SA), “Asian,” or “Other.” Clinical parameters were obtained through chart review. The primary outcome was door‐to‐electrocardiogram (D2ECG) time. ECG times were log‐transformed and two linear regression models, controlling for important demographic, system, and clinical factors, were fit.

Results

Of 448 participants, 214 (48%) reported white identity, 115 (26%) SA, 83 (19%) Asian, and 36 (8%) “Other.” Asian respondents were younger and more likely to report initial discomfort as “low” and be accompanied by family; respondents identifying as “Other” were more likely to report initial discomfort as “high.” There was no difference in D2ECG time between white participants and all other groups, but there were statistically significant differences by sex: women had longer D2ECG times than men. Exploring more specific racial identities revealed similar findings: no significant differences between the white, SA, Asian, and other groups, while sex (women had 13.4% [95% confidence interval, 0.81%–27.57%] longer D2ECG times) remained statistically significantly different in the adjusted models.

Conclusion

Although racial/ethnicity‐based differences in aspects of ACS care have been previously identified, we found no differences in the current study of early ED care in a Canadian urban setting. However, female patients experience longer D2ECG times, and this may be a target for process improvements.

Ethyl Glucuronide as a Long-term Alcohol Biomarker in Fingernail and Hair. Matrix Comparison and Evaluation of Gender Bias

Aims

This work aimed to assess the performance of hair and fingernail ethyl glucuronide (EtG) measurement for use as a biomarker of alcohol consumption in persons with known drinking history across a range of drinking behaviours.

Methods

EtG concentrations were assessed from the hair and fingernails of 50 study participants. Alcohol consumption of the previous 90 days was assessed by participant interview using the alcohol timeline follow-back method. EtG concentration was determined using LC–MS-MS using a method which was validated and accredited to ISO/IEC 17025 standards.

Results

There was significant correlation between alcohol consumption and EtG concentrations found in hair and fingernail samples across the study group (n = 50). From participants testing positive for EtG (male n = 14, female n = 13) no significant difference was found between male and female EtG levels in either hair or fingernails. Across all participants there was no significant difference in hair or fingernail EtG concentration between male (n = 23) and females (n = 27).

Conclusions

Our results support the use of EtG to indicate alcohol consumption over the previous 90 days, or ~3 months as is the normal practice in hair analysis. The results confirm that fingernails can be a useful alternative matrix where hair samples are not available.

Patient indications for Mohs micrographic surgery: a clinical practice guideline

Objective

The purpose of the present work was to develop evidence-based indications for Mohs micrographic surgery in patients with a diagnosis of skin cancer.

Methods

The guideline was developed by Cancer Care Ontario's Program in Evidence-Based Care, together with the Melanoma Disease Site Group and the Surgical Oncology Program, through a systematic review of relevant literature, patient- and caregiver-specific consultation, and internal and external reviews.

Recommendation 1

Given a lack of high-quality, comparative evidence, surgery (with postoperative or intraoperative margin assessment) or radiation (for those who are ineligible for surgery) should remain the standard of care for patients with skin cancer.

Recommendation 2

Mohs micrographic surgery is recommended for patients with histologically confirmed recurrent basal cell carcinoma of the face and is appropriate for primary basal cell carcinomas of the face that are larger than 1 cm, have aggressive histology, or are located on the H zone of the face.

Recommendation 3

Mohs micrographic surgery should be performed by physicians who have completed a degree in medicine or equivalent, including a Royal College of Physicians and Surgeons of Canada Specialist Certificate or equivalent, and have received advanced training in Mohs micrographic surgery.

Pesticides related to land use in watersheds of the Great Lakes basin

In this study, we evaluated the distribution and concentrations of a range of neonicotinoid insecticides (NNIs) and other insecticides, fungicides, biocides and selected herbicides in watersheds that drain into the lower Great Lakes in Ontario, Canada. Polar Organic Chemical Integrative Samplers (POCIS) were deployed in 18 watersheds during late May to late June of 2016. Grab samples were also collected in 7 of these watersheds. There was generally good agreement between the time-weighted average concentrations of pesticides estimated from the POCIS and the concentrations detected in grab samples. The NNIs, thiamethoxam, clothianidin and imidacloprid, were present in several watersheds at concentrations that exceeded the Canadian Water Quality Guideline for imidacloprid of 0.23 μg/L. The new generation insecticides, flonicamid and flupyradifurone were also detected in some watersheds, which is the first report of these pesticides in the peer-reviewed literature. Atrazine, 2,4-D, dicamba, carbendazim, thiophanate methyl and several azole-based fungicides were also widely detected. Discriminant Function Analysis (DFA) indicated that a high proportion (i.e. >80%) of the watersheds could be discriminated from each other on the basis of the pattern of pesticides detected in surface waters, and the proportion of field crops in the watershed.

UV photofragmentation dynamics of acetaldehyde cations prepared by single-photon VUV ionization

UV excitation of cold acetaldehyde cations prepared by single-photon VUV ionization results in remarkably rich photochemistry.

Ankylosing Spondylitis Response to TNF Inhibition Is Gender Specific: A 6-Year Cohort Study

Aim Recent studies have suggested gender-specific differences with respect to both baseline disease activity and severity in ankylosing spondylitis (AS). Tumour necrosis factor inhibitors (TNFi) have shown significant benefit in AS but there may be gender-specific differences regarding responses to TNFi therapy. Methods AS patients with active disease despite adequate trials of NSAIDs were commenced on TNFi and followed in a biologic clinic between 2004 and 2011. Response to treatment was measured based on clinical and serological outcomes. Baseline radiographic data were also collected where available. Results 147 AS patients commenced TNFi therapy and were followed in a biologic clinic between 2004 and 2011. One-hundred and six (72%) of the patients were male and 90 (61%) were current or ex-smokers. The specific TNFi prescribed included etanercept (74 patients, 50.3%), adalimumab (51 patients, 34.7%), infliximab (21 patients, 14.2%) and golimumab (1 patient, 0.7%). The median mSASSS score was 11 (interquartile range 5-35). At baseline, the metrology indices (BASMI) were significantly lower in women (2.6 v 4; p=0.01) but all other clinical indices were similar. At 3 months, female patients had significantly worse median disease activity and functional indices (BASDAI: 4 v 2; p<0.01; BASFI: 3 v 2; p=0.03) than male patients. In addition, females had higher median ESR (19 v 6; p<0.01) which correlated with their disease activity indices (r=0.42, p=0.02). Discussion Despite similar disease activity at baseline, post-TNFi therapy women had significantly higher disease activity. Furthermore, ESR levels in women during therapy correlated with their clinical disease activity scores. Further exploration of these gender-specific differences is crucial for a greater understanding of the pathogenesis of AS as well as development of targeted therapies.

The Normal Accommodative Convergence/Accommodation (AC/A) Ratio

BACKGROUND AND PURPOSE

To measure the Accommodative Convergence (PD)/Accommodation ratio (D) (AC/A) in a cohort of visually normal participants using common clinical methods.

PATIENTS AND METHODS

AC/A ratios of 50 visually normal subjects were measured using the distance gradient (DG), near gradient (NG), gradient using synoptophore, (SG) and heterophoria (H) methods in line with current clinical practice.

RESULTS

Median AC/A ratios for NG, DG, SG, and H were 2.0 (IQR 2.0), 1.0 (IQR 0.6), 1.0 (IQR 0.6), and 5.0 (IQR 1.7), respectively. There was a statistically significant difference in ratios calculated between all methods in the same subjects (p < 0.05). There were differences in DG vs NG, DG vs H, SG vs H, and NG vs H (p < 0.05); only DG vs SG did not differ significantly (p > 0.05). Lens power toleration was found to affect AC/A ratio in DG (p < 0.05) and latent deviation was significantly associated with (p < 0.05) AC/A ratio in NG.

CONCLUSION

Calculated AC/A ratios in this cohort were lower than historically cited normal (3-5:1) in all gradient methods. There were differences in AC/A values in the same subjects calculated with different gradient methods, indicating that these methods are not interchangeable and a universal normal range should not be applied for all methods.

Neonicotinoid pesticides in drinking water in agricultural regions of southern Ontario, Canada

Because of the persistence and solubility of neonicotinoid insecticides (NNIs), there is concern that these compounds may contaminate sources of drinking water. The objective of this project was to evaluate the distribution of NNIs in raw and treated drinking water from selected municipalities that draw their water from the lower Great Lakes in areas of southern Ontario, Canada where there is high intensity agriculture. Sites were monitored using Polar Organic Chemical Integrative Samplers (POCIS) and by collecting grab samples at six drinking water treatment plants. Thiamethoxam, clothianidin and imidacloprid were detected in both POCIS and grab samples of raw water. The frequency of detection of NNIs was much lower in treated drinking water, but some compounds were still detected at estimated concentrations in the low ng L^-1 range. Thiamethoxam was detected in one grab sample of raw drinking water at a mean concentration of 0.28 μg L^-1, which is above the guidelines for drinking water recommended in some jurisdictions, including the European Union directive on pesticide levels <0.1 μg L^-1 in water intended for human consumption. Further work is required to determine whether contamination of sources of drinking water with this class of insecticides is a global problem in agricultural regions.

Induction of Neointima Formation by Platelet Derived Angiogenesis Fraction in a Small Diameter, Wide Pore, PTFE Graft

Enhancement of endothelialization and patency of a small diameter (2 mm), wide pore, PTFE graft was attempted by coating the luminal surface with a platelet derived angiogenesis fraction (PDAF) and implanting it in a rat model. PDAF was delivered to the grafts by combining it with a carrier polymer. PDAF-treated grafts were initially implanted in the retroperitoneum for 21 days followed by removal of one for histology and in situ end to side bypass to the infrarenal aorta for the other. Vascularized grafts were examined at 14 days for patency and 100 days for patency and histology. Significant differences were noted in transmural ingrowth of capillaries and tissue at 21 days post implantation in PDAF-treated verses untreated grafts. Similarly, near significance was noted in capillary ingrowth and significance was noted in tissue ingrowth at 100 days in PDAF-treated grafts. Despite favorable trends particularly early in the time course, no significant differences in graft patency, endothelialization, or hydroxyproline content was demonstrated between PDAF-treated and untreated grafts. Results of this preliminary study are encouraging for further study of PDAF-treated PTFE grafts and the potential that rapid vascularized neointima formation results improved in graft patency rates.

Photodissociation dynamics of acetone studied by time-resolved ion imaging and photofragment excitation spectroscopy

The photodissociation dynamics of acetone has been investigated using velocity-map ion imaging and photofragment excitation (PHOFEX) spectroscopy across a range of wavelengths spanning the first absorption band (236-308 nm). The radical products of the Norrish Type I dissociation, methyl and acetyl, as well as the molecular product ketene have been detected by single-photon VUV ionization at 118 nm. Ketene appears to be formed with non-negligible yield at all wavelengths, with a maximum value of Φ ≈ 0.3 at 280 nm. The modest translational energy release is inconsistent with dissociation over high barriers on the S₀ surface, and ketene formation is tentatively assigned to a roaming pathway involving frustrated dissociation to the radical products. Fast-moving radical products are detected at λ ≤ 305 nm with total translational energy distributions that extend to the energetic limit, consistent with dissociation occurring near-exclusively on the T₁ surface following intersystem crossing. At energies below the T₁ barrier a statistical component indicative of S₀ dissociation is observed, although dissociation via the S₁/S₀ conical intersection is absent at shorter wavelengths, in contrast to acetaldehyde. The methyl radical yield is enhanced over that of acetyl in PHOFEX spectra at λ ≤ 260 nm due to the onset of secondary dissociation of internally excited acetyl radicals. Time-resolved ion imaging experiments using picosecond duration pulses at 266 nm find an appearance time constant of τ = 1490 ± 140 ps for CH₃ radicals formed on T₁. The associated rate is representative of S₁ → T₁ intersystem crossing. At 284 nm, CH₃ is formed on T₁ with two distinct timescales: a fast <10 ns component is accompanied by a slower component with τ = 42 ± 7 ns. A two-step mechanism involving fast internal conversion, followed by slower intersystem crossing (S₁ → S₀ → T₁) is proposed to explain the slow component.

UV photodissociation dynamics of CHI2Cl and its role as a photolytic precursor for a chlorinated Criegee intermediate

Photolysis of geminal diiodoalkanes in the presence of molecular oxygen has become an established route to the laboratory production of several Criegee intermediates, and such compounds also have marine sources. Here, we explore the role that the trihaloalkane, chlorodiiodomethane (CHI₂Cl), may play as a photolytic precursor for the chlorinated Criegee intermediate ClCHOO. CHI₂Cl has been synthesized and its UV absorption spectrum measured; relative to that of CH₂I₂ the spectrum is shifted to longer wavelength and the photolysis lifetime is calculated to be less than two minutes. The photodissociation dynamics have been investigated using DC slice imaging, probing ground state I and spin-orbit excited I* atoms with 2 + 1 REMPI and single-photon VUV ionization. Total translational energy distributions are bimodal for I atoms and unimodal for I*, with around 72% of the available energy partitioned in to the internal degrees of freedom of the CHICl radical product, independent of photolysis wavelength. A bond dissociation energy of D₀ = 1.73 ± 0.11 eV is inferred from the wavelength dependence of the translational energy release, which is slightly weaker than typical C-I bonds. Analysis of the photofragment angular distributions indicate dissociation is prompt and occurs primarily via transitions to states of A'' symmetry. Complementary high-level MRCI calculations, including spin-orbit coupling, have been performed to characterize the excited states and confirm that states of A'' symmetry with highly mixed singlet and triplet character are predominantly responsible for the absorption spectrum. Transient absorption spectroscopy has been used to measure the absorption spectrum of ClCHOO produced from the reaction of CHICl with O₂ over the range 345-440 nm. The absorption spectrum, tentatively assigned to the syn conformer, is at shorter wavelengths relative to that of CH₂OO and shows far weaker vibrational structure.

Competing pathways in the near-UV photochemistry of acetaldehyde

Time-resolved ion imaging measurements have been performed to explore the photochemistry of acetaldehyde at photolysis wavelengths spanning the range 265–328 nm.