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Perceived health and distresses are associated with the practice of lifestyle modifications, which increases the risk of diabetes and hypertension-related complications. This study aimed to define the characteristics and distribution of perceived health and distresses across the states between people with diabetes and hypertension. Data were derived from a national survey of US adults aged ≥18 years who were interviewed via phone call. Perceived health and distresses were assessed through corresponding questions. An amount of 333,316 respondents (43,911 with diabetes and 130,960 with hypertension) were included in the analysis; 61.8% of people with diabetes and 74.5% of people with hypertension reported having good or better health, while residents in the Southwest region perceived poor health statuses and more distresses. Education level (diabetes: odds ratio [OR] = 0.47–0.79, hypertension: OR = 0.42–0.76), employment status level (diabetes: OR = 1.40–2.22, hypertension: OR = 1.56–2.49), and household income (diabetes: OR = 0.22–0.65, hypertension: OR = 0.15–0.78) were significant factors associated with poorly perceived health among people with diabetes and hypertension, and the use of technology and strategies for policymakers are suggested to improve the perceived health status in this regard. [ABSTRACT FROM AUTHOR]

Background: Dementia has become one of the leading causes of death across the world. Aims: The aim of this study was to investigate the incidence, prevalence, and mortality of dementia in China between 2010 and 2020, and to investigate any geographical, age, and sex differences in the prevalence and incidence of dementia. Methods: Five databases were searched. The Joanna Briggs Institute (JBI) critical appraisal tool was used to assess the quality of the included studies. A random-effects meta-analysis was performed to estimate the pooled prevalence of dementia. Subgroup analysis was based on the type of dementia. The incidence and mortality of dementia were synthesized qualitatively. Results: A total of 19 studies were included. The meta-analysis showed that the prevalence of dementia was 6% (95%CI 5%, 8%), the prevalence of Alzheimer's disease (AD) was 5% (95%CI 4%, 6%), and the prevalence of vascular dementia (VaD) was 1% (95%CI 0%, 2%). The subgroup analysis showed that the prevalence rates of dementia in rural (6%, 95%CI 4%, 8%) and urban areas were similar (6%, 95%CI 4%, 8%). Deaths due to dementia increased over time. Conclusion: The prevalence, incidence, and mortality of dementia increased with age and over time. Applying consistent criteria to the diagnosis of cognitive impairment and dementia is necessary to help with disease monitoring. Promoting dementia knowledge and awareness at the community level is necessary. [ABSTRACT FROM AUTHOR]

Background: Access to healthcare is part of every individual's human rights; however, many studies have illustrated that ethnic minority patients seem to be confronted with barriers when using healthcare services. Understanding how healthcare utilities are accessed from the perspective of patients and why healthcare disparities occur with patients from a minority background has the potential to improve health equality and care quality. This qualitative systematic review aims to gain insights into the experiences of people with chronic respiratory diseases (CRDs) from a minority background and explore factors contributing to their experiences in accessing healthcare to inform related health policy makers and healthcare providers. Methods: This systematic review complied with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, where the Joanna Briggs Institute meta-aggregative instrument facilitated the qualitative synthesis. The study protocol was registered with PROSPERO (CRD42022346055). PubMed, Scopus, Web of Science, and CINAHL were the databases explored. Results: From the papers selected, 47 findings were derived from 10 included studies, and four synthesised findings were generated: (1) the relationship between patients and healthcare professionals affects the usage of healthcare services; (2) patients' perceptions and cultural beliefs affect their compliance with disease management; (3) personal behaviours affect the usage of healthcare services; and (4) health resource inequalities have an impact on accessing healthcare services. Conclusions: This systematic review demonstrates that ethnic minorities with CRDs face inequalities when engaging in healthcare. The relationship between patients and clinicians impacting the use of healthcare is the most pivotal discovery, where not speaking the same language and being of a different race alongside the accompanying criticism and faith in facilities are key contributors to this effect. In addition, the thinking patterns of these marginalised groups may reflect their cultural upbringing and diminish their engagement with therapies. This paper has uncovered ways to attenuate inequalities amongst ethnic minorities in engaging with healthcare providers and provides insight into building effective equity-promoting interventions in healthcare systems. To overcome these disparities, coaching doctors to communicate better with minority cohorts could help such patients to be more comfortable in connecting with medical facilities. [ABSTRACT FROM AUTHOR]

Background: High short-acting β2-agonist (SABA) use and/or inhaled corticosteroid (ICS) underuse are common and are associated with poor asthma outcomes. This study explored patients' and healthcare practitioners' (HCPs') perspectives to contextualize asthma treatment patterns observed in real-world studies.Methods: Data were collected using online surveys from HCPs and people with asthma (≥ 18 years old with a confirmed asthma diagnosis of any severity) who had consented to research participation through the Clinical Practice Research Datalink. Data were analysed using descriptive statistics.Results: In total, 76 HCPs and 63 patients were invited to take part. Of 48 valid HCP responders, 54.2% (n=26) reported scheduling an annual asthma treatment review with their patients and 83.3% of general practitioners (n=40) had prescribed repeated inhalers at the patient's request. Of 47 valid patient responders, 57.4% (n=27) reported using their reliever (SABA) inhaler daily and 55.3% of patients (n=26) reported being prescribed a preventer inhaler. Of the total patient responders, 31.9% (n=15) reported that they never used their preventer inhaler. Consistent annual adherence with preventer inhalers was reported by 44.7% of all valid responders (n=21), while other patients admitted to using preventers intermittently.Conclusion: SABA and ICS prescription patterns are driven by a combination of HCP and patient factors. Opportunities exist to improve asthma control and behaviours around inhaler use. [ABSTRACT FROM AUTHOR]

Background: Communication is an important clinical tool for the prevention and control of diseases, to advise and inform patients and the public, providing them with essential knowledge regarding healthcare and disease management. This study explored the experience of communication between healthcare professionals (HCPs) and people with long-term lung conditions, from the patient perspective. Methods: This qualitative study analyzed the experience of people with chronic lung disease, recruited via Asthma & Lung UK (A&LUK) and COPD research databases. A&LUK invited people who had expressed a desire to be involved in research associated with their condition via their Expert Patient Panel and associated patients' groups. Two focus group interviews (12 participants) and one individual interview (1 participant) were conducted. Thematic analysis was used for data analysis. Results: Two main themes were identified and we named them 'involving communication' and 'communication needs to be improved. 'They included seven subthemes: community-led support increased the patients' social interaction with peers; allied-HCP-led support increased patients' satisfaction; disliking being repeatedly asked the same basic information; feeling communication was unengaging, lacking personal specifics and the use of medical terminology and jargon. Conclusions: The study has identified what most matters in the process of communication with HCPs in people with long-term respiratory diseases of their healthcare management. The findings of the study can be used to improve the patient–healthcare professional relationship and facilitate a better communication flow in long-term healthcare management. [ABSTRACT FROM AUTHOR]

Aim: The aim of the study is to provide insight and facilitate a deeper understanding of family members who have experienced their older family member's suicide. Design: Interpretative phenomenological analysis (IPA) study. Methods: Semi‐structured individual interviews with five family members of older people who died by suicide recruited from a rural area of Shanxi Province, China. Smith's (2009) six steps of IPA was used for data analysis. Results: Three main themes emerged from the study: (a) Initial psychological reactions; (b) Long‐term life effects; (c) Social attitudes. The study shows how the family members of older people who died by suicide have experienced stigmatization and felt largely ignored. A suicide event poses a challenge to the future living quality of the family members. The study also highlights that it is necessary to pay attention to families of older people who died by suicide and providing support is required to improve the quality of life of these family members in rural China. Conclusion: The study adds to the understanding of the lived experience of family members of older people who died by suicide in less economically developed rural areas. Patient or Public Contribution: Patients and the public were not involved in the design, conduct or reporting of this study. Participants of this study helped with recruitment via snowball sampling. [ABSTRACT FROM AUTHOR]

Background and aims: Dementia is recognized globally as a massive burden on public health and wider society. It is a major cause of disability and mortality amongst older people. China has the largest population of people with dementia worldwide, accounting for approximately 25% of the entire global population of people with dementia. The study investigated the perceived experiences of care giving and care receiving in China, with one area identified in the data concerning the extent to which the participants discussed death. The research also explored the meaning of living with dementia in modern China, where the economy, demography and culture are rapidly changing. Method: The qualitative approach of interpretative phenomenological analysis was used for this study. Semi-structured interviews were used for data collection. Finding: The paper reports on one specific finding concerning death as a way out of the situation that participants found themselves in. Conclusion: The study described and interpreted one of the specific issues, 'death', in the participants' narratives. This finding reflects how psychological and social factors, such as stress, social support, healthcare cost, caring burden and medical practice have created the participants' thoughts of 'wishing to die' and the reasons why they believe 'death is a way to reduce burden'. It calls for an understanding, supportive social environment and a reconsideration of a culturally and economically appropriate family-based care system. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to explore the lived experiences of a rural dwelling person living with dementia and his children. Using a phenomenological case study methodology, it aims to explore the health-related and personal dilemmas faced by multiple family members who provide care to a person living with dementia in a rural area in Henan, China. The study also investigates the barriers to quality dementia care in this kind of setting in order to inform the relevant stakeholders. Method: A phenomenological case study was designed for this study. The case that formed the focus of the research included a person living with dementia and multiple family members. Semi-structured in-depth interviews were undertaken with the five family members of the person living with dementia. Smith's interpretative phenomenological analysis was used for data analysis. Findings: Three major themes were identified: (1) Dementia as a normal ageing process or a bad disease; (2) Commitment to and challenges of family caring and (3) Life in rural areas. Conclusion: With the development of China's economy and its social-cultural changes, traditional home-based care provision in rural areas of China is being challenged for people with dementia who have multiple children. It suggests that there needs to be an exploration into providing more appropriate care for people with dementia living in rural settings. It also suggests that more support is required to increase dementia awareness and to improve the quality of life of people with dementia and their families in rural China. [ABSTRACT FROM AUTHOR]

Background and objectives: Despite many studies on 'life after care' for family caregivers with dementia in Western societies, little is known about the bereavement experiences of family caregivers in China. The aim of this study was to explore the experience of bereavement on family members of people with dementia in China. It also hopes to inform end-of-life care within communities, providing a theoretical basis for improving the quality of life of bereaved family caregivers. Methods: Interpretative phenomenological analysis approach was adapted for this study. Purposive sampling was used to recruit former family caregivers of people with dementia. Semi-structured in-depth interviews with 12 bereaved family caregivers were collected. Thematic analysis was used for data analysis. Findings: Five themes were identified: recalling the past life, lack of support, uncertainty of the future, social withdrawal and acceptance and release. Conclusion: The experiences of bereavement on family members of people with dementia in China are socially and culturally complex. This article recommends that bereavement should be supported throughout the palliative process of community services and healthcare services. Providing all-round support and education on death and dying can help the family caregivers to pass through grief and help them to maintain their normal life. [ABSTRACT FROM AUTHOR]

Background and aims: Globally, two thirds of people with dementia are cared for by their families or friends. Family caregivers' coping strategies of managing the caregiving burden of dementia have been studied widely in western literature. However, few attempts have been made to explore the experience of family caregivers' coping strategies in China. The aim of this study was to explore the family caregivers' coping strategies when caring for people with dementia in one city in the province of Shandong, China. Methods: Fourteen family caregivers were individually interviewed, and interpretative phenomenological analysis was used to identify themes within different family members. Results: Four key themes were found: (a) being filial; (b) changing self and self-care; (c) seeking help; and (d) having hope and continuing life. Conclusion: The study illustrates the different strategies developed by family members in order to cope with their new roles when caring for a relative who has dementia. It shows that cultural belief of filial piety plays a large role across these various coping strategies. It highlights how responsibility has been maintained and influenced by the specific sociocultural context. The results provide a useful foundation for developing interventions that support family caregivers cope with the burden of caring in this population. [ABSTRACT FROM AUTHOR]

Ageing in place is a key principle of older care services in many countries, especially in China where the social convention, cultural expectation and legal obligation emphasise that looking after parents is the children's responsibility. As a result, the majority of older, frail Chinese have been cared for at home by their families. Previous studies have argued that being cared for at home contributes positively to the well-being and quality of life of older people and to economic cost. However, due to the sociocultural, economic and demographic changes in China, older people and their family caregivers are facing many challenges as they 'age in place' at home. This study aims to explore the meaning of family supported home care in China from the perspectives of people with dementia and family caregivers. The study is based on qualitative data collected from 24 people with dementia and family caregivers recruited from one mental health centre in Shandong province, China. Three main themes and nine subthemes were found: home care may create a sense of social isolation; home care is a burden; home care versus institutional care. The study suggests that while home care may bring social and psychological benefits, it also can be a barrier to building social connection, receiving social support, and other related services in China. [ABSTRACT FROM AUTHOR]

We point out that normal modes and frequencies of molecules and molecular complexes can be obtained directly from a harmonically driven molecular dynamics calculation. We illustrate this approach for HOD and H[SUB5]O[SUP+,SUB2] and then discuss its potential advantages over the standard Hessian-based approach for large molecules. [ABSTRACT FROM AUTHOR]

The filial piety model of family centred care has dominated Chinese society for thousands of years. The ways in which filial piety is presented are being modified and modernised as China undergoes social transitions. The study aims to understand the meaning of filial piety for people with dementia and family caregivers. Semi-structured interviews with people with dementia (n = 10) and family caregivers (n = 14) were conducted. Data were analysed using interpretative phenomenological analysis. Three themes emerged: (a) 'Being filial is a cultural continuity and my future investment'. (b) 'The changed perception and ways of being filial'. (c) 'Filial responsibility is a social and cultural convention, but not my personal choice'. This study highlights the importance of cultural values in family care decision making and in shaping filial responsibilities. It indicates that filial obligation can be maintained through social support, even though the nature of filial piety has been changed by social transitions. [ABSTRACT FROM AUTHOR]

Background: Bristol stool form 1 and 2 is an important predictor of inadequate bowel preparation. Aim: To evaluate the efficacy of supplemental preparation in bowel cleansing quality among patients with Bristol stool form 1 and 2, as well as the feasibility of tailored bowel preparation guided by Bristol stool form scale. Methods: Patients with Bristol stool form 1 and 2 from 3 Chinese tertiary hospitals randomly received either 2 L PEG-ELP (group A) or 10 mg bisacodyl plus 2 L PEG-ELP (group B); patients with Bristol stool form 3 to 7 received 2 L PEG-ELP (group C) for bowel preparation. The primary endpoint is the rate of adequate bowel reparation for the whole colon. The adequate bowel preparation rate for separate colon segments, the polyp detection rate (PDR), tolerability, acceptability, sleeping quality and compliance were evaluated as secondary endpoints. Results: 700 patients were randomized. In per-protocol analysis, patients in group B attained significantly higher successful preparation rate than group A (88.7% vs. 61.2%, p<0.001) and similar with group C (88.7% vs. 85.0%, p = 0.316). The PDR in group B was significantly higher than group A (43.2% vs. 25.7%, p<0.001). Acceptability was much higher in group B and C. Conclusions: 10 mg bisacodyl plus 2 L PEG-ELP can significantly improve both bowel preparation quality and PDR in patients with Bristol stool form 1 and 2. Bristol stool form scale may be an easy and efficient guide for tailored bowel preparation before colonoscopy. [ABSTRACT FROM AUTHOR]

We produced graphite nanoplatelets (GNP)/silicone resin composites at various loadings. The utilized GNPs were characterized by two-dimensional structure with high aspect ratio (~1810), and the GNP with approximately 10-30 nm thickness and 10-50 µm in length evenly dispersed throughout the resin matrix, which enables that GNPs effectively act as thermally conductive medium, thus contributed considerably to the formation of an efficient three-dimensional network for heat flow. The thermal conductivities of 5, 10, 15, and 20 wt.% GNP composite were 0.35, 1.02, 1.32, and 2.01 W/(m K), and were ca. 0.9, 4.7, 6.3, and 10.2 times higher than that of silicone resin at room temperature, respectively. The thermal conductivity decreased with elevated temperature in 25-200 °C, which was reminiscent at higher loading. Differential scanning calorimeter analysis showed that GNP addition increased the curing temperature of silicone resin from 90 to 119 °C, probably by hindering the free movement (mobility) of the silicone chains. The result showed that the GNP not only reduced the CTE but also improved the thermal stability of composite simultaneously. [ABSTRACT FROM AUTHOR]

In this article, the ethylene propylene diene methylene rubber composites filled with pretreated multi-walled carbon nanotubes were prepared by a double-roll milling dispersion method. The thermal and mechanical properties of the composites were measured and evaluated. The morphology of pretreated multi-walled carbon nanotubes was studied via transmission electron microscopy and the dispersity of multi-walled carbon nanotubes in ethylene propylene diene methylene was determined using scanning electron microscope. By means of thermogravimetric analysis, the thermal stability and oxidation resistance of ethylene propylene diene methylene filled with different content of multi-walled carbon nanotubes were examined. The results showed that the pretreated multi-walled carbon nanotubes can improve the thermal conductivity and increase the thermal decomposition temperature. However, different filling content of multi-walled carbon nanotubes showed different effects on the mechanical performance of ethylene propylene diene methylene. [ABSTRACT FROM PUBLISHER]

This paper presents a spanning tree-based genetic algorithm (st-GA) to solve optimal multistage distribution network planning. According to the topological characteristic of distribution network, it is derived that the target network contains the message of each building stage for every candidate branch and its size Thus, the multistage distribution network planning can be transformed into a problem of searching the optimal target network with the minimum total costs in the whole planning horizon. Moreover, st-GA with two specialized genetic operators can guarantee the topological feasibility and high heritability of each solution generated and overcome the defficiencies of existing GAs applied for distribution network planning. Finally, the case study is implemented to demonstrate the usefulness and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Annular pancreas is a rare congenital condition of the pancreas where pancreatic tissue either partially or completely covers the duodenum by forming a ring. Endoscopic ultrasound is rarely considered as an initial diagnostic tool for annular pancreas. We here present the case of a 48-year-old male primarily provisionally diagnosed with a pancreatic mass for which a pancreatoduodenectomy was planned. However, an endoscopic ultrasound confirmed the diagnosis of annular pancreas. [ABSTRACT FROM AUTHOR]

Aims: The study aims to analyse the tensions and the challenges of dementia care that are experienced by people with dementia and their family caregivers in China. Background: China has the largest dementia population in the world; however, dementia care services and related support services are still developing. Caring for a person with dementia is very challenging, as evidenced by many studies. As the majority of people with dementia are looked after by their family in their homes in China, it is very important to understand what people with dementia and their family caregivers are experiencing in the context of dementia care services that are in the process of developing. Design: Interpretative phenomenological analysis (IPA) was used. Method: Semi‐structured individual interviews with 24 participants (10 people with dementia and 14 unrelated family caregivers) recruited from a mental health centre in Shandong Province. Findings: Three main themes emerged that highlighted unmet need: (a) Lack of support services, (b) Insufficient institutional care and (c) Social attitude and social stigma towards dementia. Conclusions: These themes reveal the challenges that the participants face in the context of dementia care services that are in the process of development in China; and how their lived experiences have been affected by the constraints of social support, public services, healthcare access, long‐term care services and social stigma. Implications for practice: This study highlights the tensions that are identified by people with dementia and family caregivers. The research recommends that more support services would be beneficial for this group and would also enhance family support dementia care in China. Looking after an older family member is a culturally, socially and legally embodied norm in Chinese society, so it is important to address education for dementia awareness and the sustainability of family support care services in China by providing dementia services and resources to support both people with dementia and family caregivers. [ABSTRACT FROM AUTHOR]

Introduction: Diagnosis of asthma, chronic obstructive pulmonary disease (COPD), bronchiectasis and interstitial lung disease (ILD) can be convoluted, and limited data exist on understanding the experience of diagnosis from a patient perspective., Aim: To investigate a patient's 'route to diagnosis', particularly focusing on the time prior to seeking healthcare, and perceived experiences of the diagnostic pathway., Methods: An online survey was distributed via the UK Taskforce for Lung Health and member mailing lists to patients as well as the website and social media accounts from 23 May 2022 to 5 July 2022. Analysis was descriptive; χ 2 tests were performed to make comparisons across diseases., Results: There were 398 valid responses (COPD=156, asthma=119, ILD=67 and bronchiectasis=56). While only 9.2% of respondents who were eventually diagnosed with asthma had not heard of their disease, the corresponding percentages for COPD, ILD and bronchiectasis were 34.0%, 74.6% and 69.6%, respectively. 33.9% of people with bronchiectasis believed their delayed diagnosis was due to the health professionals' lack of expertise or knowledge-24.4% for asthma, 19.2% for COPD and 17.9% for ILD.People with COPD were more likely (37.2%) and patients with asthma less likely (10.9%) to report they did not know the signs of potential lung disease (p<0.001). People with COPD were more likely to report that they did not appreciate the severity or urgency of the situation (58.3%) than people with asthma (32.8%), ILD (43.3%) or bronchiectasis (28.6%, p<0.001). The proportion of patients reporting that they were being initially treated for another lung condition was higher in people with bronchiectasis (44.6%) and lower in people with asthma (8.4%, p<0.001)., Conclusions: Perceived reasons for diagnostic delay can help health professionals promote early diagnosis and management. Patients' limited knowledge of respiratory diseases also played a factor, indicating the necessity to promote patients' knowledge to encourage earlier help seeking., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY. Published by BMJ.)

Quasiclassical trajectory calculations are reported to investigate the effects of rotational excitation of formaldehyde on the branching ratios of the fragmentation products, H2+CO and H+HCO. The results of tens of thousands of trajectories show that increased rotational excitation causes suppression of the radical channel and enhancement of the molecular channel. Decomposing the molecular channel into "direct" and "roaming" channels shows that increased rotation switches from suppressing to enhancing the roaming products across our chosen energy range. However, decomposition into these pathways is difficult because the difference between them does not appear to have a distinct boundary. A vector correlation investigation of the CO rotation shows different characteristics in the roaming versus direct channels and this difference is a potentially useful signature of the roaming mechanism, as first speculated by Kable and Houston in their experimental study of photodissociation of acetaldehyde [P. L. Houston and S. H. Kable, Proc. Nat. Acad. Sci. 103, 16079 (2006)].

Recently, a new mechanism of formaldehyde decomposition leading to molecular products CO and H(2) has been discovered, termed the "roaming atom" mechanism. Formaldehyde decomposition from the ground state via the roaming atom mechanism leads to rotationally cold CO and vibrationally hot H(2), whereas formaldehyde decomposition through the conventional molecular channel leads to rotationally hot CO and vibrationally cold H(2). This discovery has shown that it is possible to have multiple pathways for a reaction leading to the same products with dramatically different product state distributions. Detailed investigations of the dynamics of these two pathways have been reported recently. This paper focuses on an investigation of the energy dependence of the roaming atom mechanism up to 1500 cm(-1) above the threshold of the radical channel, H(2)CO-->H+HCO. The influence of excitation energy on the roaming atom and molecular elimination pathways is reported, and the branching fraction between the roaming atom channel and molecular channel is obtained using high-resolution dc slice imaging and photofragment excitation spectroscopy. From the branching fractions and the reaction rates of the radical channel, the overall competition between all three dissociation channels is estimated. These results are compared with recent quasiclassical trajectory calculations on a global H(2)CO potential energy surface.

Detailed quasiclassical trajectory calculations of the reaction H+CH4(nu3 = 0,1)-->CH3 + H2 using a slightly updated version of a recent ab initio-based CH5 potential energy surface [X. Zhang et al., J. Chem. Phys. 124, 021104 (2006)] are reported. The reaction cross sections are calculated at initial relative translational energies of 1.52, 1.85, and 2.20 eV in order to make direct comparison with experiment. The relative reaction cross section enhancement ratio due to the excitation of the C-H antisymmetric stretch varies from 2.2 to 3.0 over this energy range, in good agreement with the experimental result of 3.0 +/- 1.5 [J. P. Camden et al., J. Chem. Phys. 123, 134301 (2005)]. The laboratory-frame speed and center-of-mass angular distributions of CH3 are calculated as are the vibrational and rotational distributions of H2 and CH3. We confirm that this reaction occurs with a combination of stripping and rebound mechanisms by presenting the impact parameter dependence of these distributions and also by direct examination of trajectories.

We present a detailed experimental and theoretical investigation of formaldehyde photodissociation to H(2) and CO following excitation to the 2(1)4(1) and 2(1)4(3) transitions in S(1). The CO velocity distributions were obtained using dc slice imaging of single CO rotational states (v=0, j(CO)=5-45). These high-resolution measurements reveal the correlated internal state distribution in the H(2) cofragments. The results show that rotationally hot CO (j(CO) approximately 45) is produced in conjunction with vibrationally "cold" H(2) fragments (v=0-5): these products are formed through the well-known skewed transition state and described in detail in the accompanying paper. After excitation of formaldehyde above the threshold for the radical channel (H(2)CO-->H+HCO) we also find formation of rotationally cold CO (j(CO)=5-28) correlated to highly vibrationally excited H(2) (v=6-8). These products are formed through a novel mechanism that involves near dissociation followed by intramolecular H abstraction [D. Townsend et al., Science 306, 1158 (2004)], and that avoids the region of the transition state entirely. The dynamics of this "roaming" mechanism are the focus of this paper. The correlations between the vibrational states of H(2) and rotational states of CO formed following excitation on the 2(1)4(3) transition allow us to determine the relative contribution to molecular products from the roaming atom channel versus the conventional molecular channel.

We review the photodissociation dynamics of formaldehyde with an emphasis on recent calculations that make use of a global ab initio-based potential energy surface for the S(0) state. These calculations together with recent experiments reveal striking departures from conventional transition state theory for the formation of the molecular products H(2) + CO. The evidence for this departure is reviewed in detail by examining properties of the new potential surface and results of quasiclassical trajectory dynamics calculations using this surface. We also review very recent work on the dynamics governing the formation of radical products, H + HCO. These products can be formed on the T(1) surface as well as the S(0) one, and we present some results contrasting the dynamics on these two surfaces. This work makes use of a new semi-global ab initio-based T(1) potential energy surface.

We report an ab initio-based global potential energy surface for H+CH4 that describes the abstraction and exchange reactions. The PES, which is invariant with respect to any permutation of five H atoms, is a fit to 20,728 electronic energies calculated using the partially spin-restricted coupled-cluster method (RCCSD(T)) with a moderately large basis (aug-cc-pVTZ). A first set of quasiclassical trajectory calculations using this PES are reported for the H+CD4-->HD+CD3 reaction at collision energies of 0.65 and 1.52 eV and are compared to experiment and recent direct dynamics calculations done with density functional theory.

We report quasiclassical trajectory calculations of the dynamics of the two reaction channels of formaldehyde dissociation on a global ab initio potential energy surface: the molecular channel H(2)CO-->H(2) + CO and the radical H(2)CO-->H + HCO. For the molecular channel, it is confirmed that above the threshold of the radical channel a second, intramolecular hydrogen abstraction pathway is opened to produce CO with low rotation and vibrationally hot H(2). The low-j(CO) and high-nu(H(2) ) products from the second pathway increase with the total energy. The competition between the molecular and radical pathways is also studied. It shows that the branching ratio of the molecular products decreases with increasing energy, while the branching ratio of the radical products increases. The results agree well with very recent velocity-map imaging experiments of Suits and co-workers and solves a mystery first posed by Moore and co-workers. For the radical channel, we present the translational energy distributions and HCO rotation distributions at various energies. There is mixed agreement with the experiments of Wittig and co-workers, and this provides an indirect confirmation of their speculation that the triplet surface plays a role in the formation of the radical products.