A new grading assessment of eosinophilic esophagitis using red dichromatic imaging: a pilot study.

BACKGROUND AND AIMS: The endoscopic reference score using white-light imaging (WLI) is utilized for objectively evaluating the severity of findings in patients with eosinophilic esophagitis. A novel image-enhanced endoscopy technique, red dichromatic imaging (RDI), can visualize deeper vessels in the GI tract, which may assess edema more precisely than WLI. METHODS: A total of 21 consecutive patients with eosinophilic esophagitis were prospectively evaluated. Patients were categorized according to 3 grades based on the visibility of vessels with RDI. Clinical features, such as peak eosinophil counts and presence of symptoms, were reviewed. RESULTS: There were 10 patients with RDI Grade 0/1 and 11 patients with RDI Grade 2. Peak eosinophil counts and the prevalence of heartburn were significantly higher in patients with RDI Grade 2 than in patients with RDI Grade 0/1. CONCLUSIONS: The severity of eosinophilic infiltration could be predicted more precisely using RDI than by evaluations with WLI.

Noonan Syndrome-related Myeloproliferative Disorder Occurring in the Neonatal Period: Case Report and Literature Review.

Noonan syndrome-related myeloproliferative disorder (NS/MPD) and juvenile myelomonocytic leukemia (JMML) are rare MPDs that occur in young children. We herein report a case of NS/MPD with neonatal onset. The patient had a characteristic appearance and high monocyte count in the peripheral blood and bone marrow. Genetic testing showed the E139D mutation in PTPN11 ; however, the patient did not meet all the diagnostic criteria for JMML, and we thus diagnosed him with NS/MPD. Eight other cases of NS/MPD with neonatal onset are also summarized. The initial presentation varied, and the prognosis was considered poor compared with previous reports of NS/MPD.

Serum albumin levels as a useful complementary marker for erectile dysfunction in ulcerative colitis: A cross-sectional study.

OBJECTIVE: Recently, a close association between ulcerative colitis (UC) and erectile dysfunction (ED) was reported. An inverse relationship between serum albumin and ED is found in patients with chronic disease. However, the association between serum albumin levels and ED in patients with UC is unclear. This study aims to investigate this issue in Japanese patients with UC. METHODS: One hundred and thirty-six Japanese male UC patients were enrolled in this study. Information on serum albumin levels and medications for UC from medical records, Sexual Health Inventory for Men (SHIM) score information from self-administered questionnaires and information on the severity of UC from physician reports were obtained from medical records, self-administered questionnaires, and reports from physicians. The participants were divided into tertiles based on the total protein, serum globulin, serum albumin, aspartate aminotransferase, and C-reactive protein levels. The definition of ED and severe ED was SHIM score < 22 and SHIM score < 8, respectively. The association between these serum markers and ED was assessed by multivariate logistic regression. RESULTS: The prevalence of severe ED in the low, moderate, and high albumin groups was 66.0%, 51.0%, and 28.3%, respectively. After adjusting for confounding factors, the low albumin group was independently and positively associated with severe ED (adjusted odds ratio: 2.74, 95% confidence interval: 1.03-7.48, p for trend =0.044). No association between other marker and ED was found. CONCLUSION: Serum albumin was independently inversely associated with severe ED in Japanese patients with UC. Hypoalbuminemia might be a useful complementary marker for assessing the prevalence and severity of ED in UC patients.

Ring-polymer Molecular Dynamics Simulation for the Adsorption of H2 on Ice Clusters (H2 O)n (n=8, 10, and 12).

In the interstellar medium, the H2 adsorption and desorption on the solid water ice are crucial for chemical and physical processes. We have recently investigated the probabilities of H2 sticking on the (H2 O)8 ice, which has quadrilateral surfaces. We have extended the previous work using classical MD and ring-polymer molecular dynamics (RPMD) simulations to the larger ice clusters, (H2 O)10 and (H2 O)12 , which have pentagonal and hexagonal surfaces, respectively. The H2 sticking probabilities decreased as the temperature increased for both cluster cases, whereas the cluster-size-independent profiles were observed. It is thought that the size independence of the probabilities is qualitatively understood from the similar binding energies for all the three cluster systems. Furthermore, the RPMD sticking probabilities are smaller than the classical ones because of the reduction in the binding energies owing to nuclear quantum effects, such as vibrational quantization.

Dynamics study of the post-transition-state-bifurcation process of the (HCOOH)H+ → CO + H3O+/HCO+ + H2O dissociation: application of machine-learning techniques.

The process of protonated formic acid dissociating from the transition state was studied using ring-polymer molecular dynamics (RPMD), classical MD, and quasi-classical trajectory (QCT) simulations. Temperature had a strong influence on the branching fractions for the HCO+ + H2O and CO + H3O+ dissociation channels. The RPMD and classical MD simulations showed similar behavior, but the QCT dynamics were significantly different owing to the excess energies in the quasi-classical trajectories. Machine-learning analysis identified several key features in the phase information of the vibrational motions at the transition state. We found that the initial configuration and momentum of a hydrogen atom connected to a carbon atom and the shrinking coordinate of the CO bond at the transition state play a role in the dynamics of HCO+ + H2O production.

Association between Mucosal Healing and Lipid Profiles in Patients with Ulcerative Colitis: A Cross-Sectional Study.

INTRODUCTION: Recent meta-analysis showed that ulcerative colitis (UC) is a risk factor for cardiovascular disease (CVD). Dyslipidemia is a well-established risk factor for CVD. However, evidence regarding inflammatory bowel disease (IBD), including UC and lipid profiles, is limited. Additionally, no study has assessed the association between endoscopic activity and lipid profiles in patients with IBD. Therefore, we aimed to clarify the association between mucosal healing (MH) and lipid profiles in patients with UC. METHODS: A total of 221 Japanese patients with UC were enrolled in this analysis. Total cholesterol (T-chol), triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C) were divided into tertiles (high, moderate, and low) based on the distributions, respectively. Self-administered questionnaire was used to obtain information regarding medication for dyslipidemia. Complete MH and MH are based on Mayo endoscopic subscore 0 and 0-1, respectively. RESULTS: The percentage of complete MH was 30.8%. In patients without medication for dyslipidemia, high HDL-C (>66 mg/dL) was significantly positively associated with complete MH (adjusted odds ratio [OR] 2.58, 95% CI: 1.04-6.64, p for trend = 0.037). In patients with nonproctitis, a positive association between HDL-C and complete MH was found (adjusted OR 3.54, 95% CI: 1.22-11.01, p for trend = 0.020). T-chol and TG were not associated with MH, regardless of medication for dyslipidemia. CONCLUSIONS: Complete MH was significantly positively associated with HDL-C in UC patients without medication for lipid. The disease extent might affect the association between complete MH and HDL-C.

Validation of red dichromatic imaging score (RDI score) to evaluate the severity of ulcerative colitis.

BACKGROUND: Red dichromatic imaging (RDI) is a new imaging technology that has been closely correlated with the activity index of ulcerative colitis (UC). Although the RDI score has been developed no study has validated a correlation between the RDI score and the activity index of UC. Therefore, this study aims to validate the RDI score prospectively. METHODS: A total of 34 patients with UC in whom colonoscopy was scheduled between May 2019 and October 2021 at our hospital were enrolled prospectively. MES, UCEIS, RDI scores, and Nancy index were evaluated in a blinded fashion. We evaluated the correlation between RDI and WLI scores using still images with histology. RESULTS: We analyzed 191 sites of colorectum. RDI score showed the positive correlation with UCEIS (r = 0.74 P < 0.0001) and MES (r = 0.78 P < 0.0001). RDI score also showed the positive correlation with Nancy index (r = 0.63 P < 0.0001). RDI score was more strongly correlated with Nancy index than UCEIS (r = 0.51) and MES (r = 0.48). CONCLUSIONS: When comparing still images of RDI and WLI scores, we showed RDI had a higher correlation to histology than WLI. CLINICAL TRIAL ID: The University Hospital Medical Information Network (UMIN000041750).

Efficacy of using red dichromatic imaging throughout endoscopic submucosal dissection procedure.

BACKGROUND: Management of bleeding during endoscopic submucosal dissection (ESD) is critical. Red Dichromatic Imaging (RDI), a novel image-enhanced endoscopy technology, has been reported to improve the visibility of deep vessels and bleeding source compared to white light imaging (WLI). We hypothesized that using RDI during the entire cutting process (full time RDI ESD: FTR-ESD), higher R0 resection rate, shorter procedure time and fewer complications could be achieved. Therefore, the aims of the present study were to investigate the efficacy and safety of FTR-ESD. METHODS: This retrospective observational study included a total of 82 consecutive patients who underwent ESD by a single expert endoscopist for 40 esophageal, 17 gastric and 25 colorectal cancers at our institution from January 2018 to March 2021. The clinicopathological data were collected from patients' medical records and the treatment outcomes were analyzed according to the treatment phase (early; 57 WLI-ESD and late; 25 FTR-ESD). RESULTS: The median of the greatest diameter of resected specimen was 40.0 mm. The median procedure time was relatively shorter in the FTR-ESD group (35 min) than in the WLI-ESD group (40 min), but the difference was not statistically significant (p = 0.34). The median dissection speed in the FTR-ESD group (27.23 mm2/min) was significantly faster than that in the WLI-ESD group (20.94 mm2/min) (p = 0.025). The dissection speed was not different among different organs. A multivariate analysis revealed that tumor size (more than 30 mm) and FTR-ESD were significant independent factors contributing to faster dissection speed (p < 0.05). There were no significant differences in the rates of en bloc resection, HM0, VM0 or occurrence of adverse events between WLI-ESD and FTR-ESD. CONCLUSIONS: FTR-ESD significantly increases the dissection speed compared to WLI-ESD. FTR-ESD can be performed safely and therapeutic outcomes in FTR-ESD are comparable with WLI-ESD. A further multicenter prospective study is warranted to confirm our results.

The relationship between manometric subtype and symptom details in achalasia.

BACKGROUND: Although dysphagia and chest pain are the two most common symptoms in patients with achalasia, the mechanism of evoking symptoms is still unknown. The aim of this study was to reveal the relationship between symptoms and the subtypes of achalasia defined by the Chicago classification. METHODS: A total of 71consecutive patients with newly diagnosed achalasia were enrolled between March 2009 and December 2017. Esophageal motility was assessed by high-resolution manometry (HRM) with the Chicago classification v 3.0. and esophagograms. Their symptoms were evaluated with structured self-reported questionnaires focused on dysphagia and chest pain. Symptom profiles and radiographic findings according to the manometric subtypes were investigated. RESULTS: Among the total 71 patients, 69 patients (97%) had dysphagia and 39 patients (54%) had chest pain. Regarding dysphagia, type II patients reported dysphagia in the throat the most, while types I and III patients mostly felt it in the epigastrium. Type II patients often felt dysphagia at the time of swallowing (41%), but this was reported in only 8.7% of Type I and 33% of Type III patients (p = 0.02). Concerning chest pain, Type I patients rarely had pain during meals (14%), but more often while sleeping (43%) and in early morning (43%), while type III patients often had pain during meals (67%). Type III patients reported that solid food caused pain more often than other types (I/II/III 0/10/33%, p = 0.09). CONCLUSIONS: Detailed symptoms of achalasia, such as its site and timing, varied by subtypes. The status of the esophageal body might induce those differences in symptoms.

A Young Japanese Patient with Spinocerebellar Ataxia Type 3 Presenting Depressive State with Cenesthopathy and Delusion: a Case Report.

Depressive state is a common complication of spinocerebellar ataxia type 3 (SCA3). To the best of our knowledge, cases of SCA3 presenting with cenesthopathy have not been described. Here, we present a case of a severe depressive state with cenesthopathy and delusion in a young Japanese man with SCA3. A 43-year-old Japanese man with SCA3 developed a severe depressive state with associated cenesthopathy and delusion. He was treated with escitalopram (10 mg/day) and olanzapine (2.5 mg/day). Computed tomography showed atrophy of the cerebellum, bilateral superior cerebellar peduncle, and tegmentum of the pons. Single-photon emission computed tomography demonstrated reduced blood flow in the cerebellum, vermis, and brainstem. After 8 weeks, his depressive state and delusion improved; however, his cenesthopathy persisted. We encountered a case of a severe depressive state with cenesthopathy and delusion in a young Japanese man with SCA3. This case supports previous studies that the cerebellum could have a role beyond motor functions.

Association between clinical outcomes and restless legs syndrome in Japanese patients with ulcerative colitis.

Restless legs syndrome (RLS) is a common sleep disorder in the Western population. The prevalence of restless legs syndrome in the Japanese population is 4.6%. Inflammatory and/or immune alteration might be associated with the development of restless legs syndrome. Ulcerative colitis is a chronic inflammatory bowel disease. Evidence regarding the association between ulcerative colitis and the prevalence of restless legs syndrome is limited. Herein, we investigated the association between clinical outcomes and the prevalence of restless legs syndrome in Japanese patients with ulcerative colitis. This was a cross-sectional study using baseline data from a prospective cohort study. Subjects in this study were 273 patients with ulcerative colitis. The definition of restless legs syndrome was achieved using a self-administered questionnaire based on the diagnostic criteria for restless legs syndrome in an epidemiological study approved by the Executive Committee of the International Restless Leg Syndrome Study Group in 2002. Clinical outcomes were clinical remission and mucosal healing. The association between clinical remission and mucosal healing and the prevalence of restless legs syndrome was assessed by multivariate logistic regression analyses. The percentage of clinical remission and mucosal healing was 58.4% and 63.1%, respectively. The prevalence of restless legs syndrome in this cohort was 4.7%. Clinical remission (adjusted odds ratio 0.23, 95% confidence interval 0.05-0.93) and mucosal healing (adjusted odds ratio 0.23, 95% confidence interval 0.05-0.90) were independently inversely associated with restless legs syndrome. No association between serum haemoglobin and restless legs syndrome was found. In conclusion, clinical remission and mucosal healing were independently and inversely associated with the prevalence of restless legs syndrome in Japanese patients with ulcerative colitis.

Effect of disease duration on the association between C-reactive protein-albumin ratio and endoscopic activity in ulcerative colitis.

BACKGROUND: A simple serum biomarker for clinical outcome in patients with ulcerative colitis (UC) remains an unmet need. Some studies have shown an association between C-reactive protein (CRP)-albumin ratio (CAR) and prognosis in patients with inflammatory bowel disease (IBD), but evidence regarding the association between CAR and UC remains limited. We evaluated the association between CAR and clinical outcome in Japanese patients with UC. METHODS: Subjects were 273 Japanese patients with UC. Clinical remission was defined as absence of both abnormally high stool frequency (< 3 per day) and rectal bleeding. Mucosal healing (MH) was defined as Mayo endoscopic subscore (MES) 0. Moderate to severe endoscopic activity was defined as MES 2-3. Subjects were divided according to CAR into tertiles (low, moderate, and high). RESULTS: The proportions of patients with clinical remission, MH, and moderate to severe endoscopic activity were 57.9%, 26.0%, and 37.0%, respectively. High CAR was significantly positively associated with moderate to severe endoscopic activity but not MH or clinical remission after adjustment (adjusted odds ratio [OR] 2.18 [95% confidence interval (CI) (1.11-4.35)], p for trend 0.023), but only in patients with long disease duration (> 7 years) (adjusted OR 2.95 [95% CI (1.06-8.79)], p for trend 0.023). CAR was not associated with clinical remission or MH. CONCLUSIONS: CAR may be significantly positively associated with moderate to severe endoscopic activity but not clinical remission or MH in Japanese patients with UC. In patients with long UC duration, CAR might be a useful serum marker for disease activity.

Ring-Polymer Molecular Dynamics and Kinetics for the H- + C2H2 → H2 + C2H- Reaction Using the Full-Dimensional Potential Energy Surface.

The H- + C2H2 → H2 + C2H- reaction is important in understanding the production mechanisms of anionic molecules in interstellar environments. Herein, the rate coefficients for the H- + C2H2 → H2 + C2H- reaction were calculated using ring-polymer molecular dynamics (RPMD), classical molecular dynamics (MD), and quasi-classical trajectory (QCT) approaches on a newly developed ab initio potential energy surface (PES) in full dimensions. PES was constructed by fitting a large number of ab initio energy points and their gradients using the permutationally invariant polynomial basis set method. There was no barrier in the reaction coordinates, which was a collinear-dominated reaction, and the reaction proceeded exothermically. It is found that the fitted PES provides the appropriate thermal rate coefficients based on all RPMD, classical MD, and QCT simulations at higher temperatures. The evaluation of the rate coefficients at lower temperatures should be conducted carefully because the fitting of the PES associated with the long-range interaction should be further improved. The spatial distribution of the nucleus allows a more effective attraction between the reactants.

Space-Making Particle Therapy for Unresectable Hilar Cholangiocarcinoma.

INTRODUCTION: Although the primary treatment option for hilar cholangiocarcinoma (HC) has been surgical resection, most patients present with unresectable advanced tumors at the time of diagnosis. Particle therapy (PT) holds great potential for HC, even though the anatomical proximity to the gastrointestinal tract prevents delivering a radical dose to the tumor. Space-making PT (SMPT), consisting of spacer placement surgery and subsequent PT, has been developed to minimize complications and maximize the therapeutic benefit of dose escalation for HC. This study aimed to conduct a dosimetric evaluation and examine the effectiveness of SMPT for the treatment of HC. METHODS: Between 2007 and 2018, 12 patients with unresectable HC treated with SMPT were enrolled. The treatment outcomes and effectiveness of spacer placement surgery were evaluated through analyses of pre- and post-surgical parameters of dose-volume histograms. RESULTS: All patients completed the planned SMPT protocol. The median survival time was 29.6 months, and the 1- and 3-year overall survival rates were 82.5% and 45.8%, respectively. The mean V95% value (volume irradiated with 95% of the planned treatment dose) of the gross tumor volume and clinical target volume after spacer placement surgery improved to 98.5% and 96.6% from preoperative values of 85.6% and 78.1%, respectively (p = 0.0196 and p = 0.0053, respectively). Grade 3 or higher adverse events after SMPT were seen in 6 patients. DISCUSSION/CONCLUSION: SMPT led to improvements in dosimetric parameters and showed good feasibility and excellent outcomes. SMPT can be a promising novel alternative for unresectable HC.

Erectile dysfunction in young patients and elderly patients by sexual encounter profile: A comparative study.

OBJECTIVE: Demand for erectile dysfunction treatments has increased not only in elderly patients but also in young patients. Reports indicate that frequent causes of erectile dysfunction in Japan are organic disorders in elderly patients and psychogenetic disorders in young patients. METHODS: We defined patients under the age of 40 as young erectile dysfunction patients, and those over 65 as elderly erectile dysfunction patients. We divided these two groups and conducted a retrospective comparative study based on medical questionnaires. We selected 215 cases of patients under the age of 40, and 176 cases of patients over the age of 65, and created a group of young patients and a group of elderly patients. We implemented the erectile hardness score, Sexual Health Inventory for Men, and sexual encounter profile questions 2 and 3 as the patient's daily clinical journal. RESULTS: The median age of young patients was 36 years, and that of elderly patients was 70 years. With respect to Sexual Health Inventory for Men, the average score was a significantly higher score in the young patients (9.26 vs 7.10, P < 0.001). Concerning erectile hardness score, young patients showed significantly higher scores in erectile hardness score (3.15 vs 2.06, P < 0.001). In terms of sexual encounter profile question 2, 50.9% of young patients responded "yes," but 24.3% of elderly patients responded, thus indicating a significantly higher score in young patients. In terms of sexual encounter profile question 3, 6.1% of young patients responded "yes," and 0.7% of elderly patients responded "yes," indicating a significantly higher in young patients. CONCLUSIONS: The results showed that many young patients with erectile dysfunction were able to perform insertion, but were unable to maintain erection.

Connexin 30 Deficiency Ameliorates Disease Progression at the Early Phase in a Mouse Model of Amyotrophic Lateral Sclerosis by Suppressing Glial Inflammation.

Connexin 30 (Cx30), which forms gap junctions between astrocytes, regulates cell adhesion and migration, and modulates glutamate transport. Cx30 is upregulated on activated astroglia in central nervous system inflammatory lesions, including spinal cord lesions in mutant superoxide dismutase 1 (mSOD1) transgenic amyotrophic lateral sclerosis (ALS) model mice. Here, we investigated the role of Cx30 in mSOD1 mice. Cx30 was highly expressed in the pre-onset stage in mSOD1 mice. mSOD1 mice with knockout (KO) of the Cx30 gene (Cx30KO-mSOD1 mice) showed delayed disease onset and tended to have an extended survival period (log-rank, p = 0.09). At the progressive and end stages of the disease, anterior horn cells were significantly preserved in Cx30KO-mSOD1 mice. In lesions of these mice, glial fibrillary acidic protein/C3-positive inflammatory astroglia were decreased. Additionally, the activation of astrocytes in Cx30KO-mSOD1 mice was reduced compared with mSOD1 mice by gene expression microarray. Furthermore, expression of connexin 43 at the pre-onset stage was downregulated in Cx30KO-mSOD1 mice. These findings suggest that reduced expression of astroglial Cx30 at the early disease stage in ALS model mice protects neurons by attenuating astroglial inflammation.

[Ulcerative colitis complicated by pyoderma gangrenosum and multiple aseptic abscesses].

A woman in her 30s was diagnosed with ulcerative colitis (UC) 4 years ago and treated with tacrolimus, azathioprine, and prednisolone 5mg (PSL). Skin ulcers appeared on the right lower leg during the course of treatment, diagnosed as pyoderma gangrenosum (PG). The patient initially improved with an increased PSL and infliximab dose, but then developed multiple skin ulcers and folliculitis throughout her body. She was transferred to our hospital for PG exacerbation treatment. She developed fever after transfer and contrast-enhanced computed tomography showed multiple abscesses in the lungs and kidneys. PSL was decreased and infliximab was discontinued. Antibiotic therapy and granulocyte/monocyte apheresis (GMA) were started. Fever persisted even after antibiotic treatment, and her general condition did not improve. A right renal abscess puncture was performed. Pus was sterile. A sterile abscess associated with PG was suspected. The PSL dose was increased to 1mg/kg and infliximab restarted. Thereafter, the patient's general condition improved, and both lung and renal abscesses contracted. Skin ulcer epithelialization was also observed. Abdominal symptoms were mild during the course of the disease, and colonoscopy showed only a localized ulcerative lesion in the rectum. The patient was later transferred to the department of dermatology at our hospital for PG treatment. Aseptic abscesses are caused by neutrophil infiltration without infection and have been reported to be associated with neutrophilic dermatosis and inflammatory bowel disease. UC-associated aseptic abscess is rare. This is only the sixth case in Japan. Aseptic abscesses can occur in various sites, including subcutaneous and deep organs, but this is the first kidney abscess case. In previous reports, PSL, infliximab, colchicine, and infliximab+GMA were used for aseptic abscesses associated with UC. They all showed abscess reduction. Aseptic abscesses associated with PG should be considered if abscess lesions occur during the course of UC, and a treatment strategy including enhanced immunosuppression should be considered.

The inverse association between unhealthy eating habit and mucosal healing among patients with ulcerative colitis.

BACKGROUND: Although the association between eating habits which can be modified and digestive diseases has been reported, to date, no research has evaluated the association between eating habits and ulcerative colitis (UC). Thus, we investigate the association between eating behavior and clinical outcome in Japanese patients with UC. METHODS: Eating quickly, eating until full, and skipping breakfast data was obtained from a self-administered questionnaire. Information on clinical outcome was collected from medical records. Mucosal healing (MH) and partial MH was defined as a Mayo endoscopic subscore of 0 or 0-1, respectively. Age, sex, BMI, current smoking, current drinking, prednisolone use, and anti-TNFα monoclonal antibody use were selected a priori as potential confounding factors. RESULTS: Study subjects consisted of 294 Japanese patients with UC. Eating at speed moderate and eating quickly were independently inversely associated with MH: the adjusted odds ratios (ORs) were 0.38 (95% confidence interval [CI] 0.16-0.85) and 0.38 (95% CI 0.17-0.81) (p for trend = 0.033). Eating until full was independently inversely associated with MH: the adjusted OR was 0.38 (95% CI 0.27-0.86). MH in patients who skipped breakfast was marginally lower than that in patients who did not skip breakfast. No association between eating habits and clinical remission or partial MH was found. CONCLUSION: Among patients with UC, eating rate and eating until full may be independently inversely associated with MH but not clinical remission.

Theoretical study of the dissociative photodetachment dynamics of the hydrated superoxide anion cluster.

The dissociative photodetachment of the hydrated superoxide anion cluster, O2-·H2O + hν → O2 + H2O + e-, is theoretically investigated using path-integral and ring-polymer molecular dynamics simulation methods, which can account for nuclear quantum effects. Full-dimensional potential energy surfaces for the anionic and lowest two neutral states (triplet and singlet spin states) are constructed based on extensive density-functional theory calculations. The calculated photoelectron spectrum agrees well with the experimental spectra measured for different photodetachment laser wavelengths. The calculated photoelectron-photofragment kinetic energy correlation spectrum also agrees well with previous experimental measurements. The dissociation mechanisms, including available energy partitioning and the importance of nuclear quantum effects in photodetachment, are discussed in detail.

Ring-Polymer Molecular Dynamics Calculations of Thermal Rate Coefficients and Branching Ratios for the Interstellar H3+ + CO → H2 + HCO+/HOC+ Reaction and Its Deuterated Analogue.

The reaction between H3+ and CO is important in understanding the H3+ destruction mechanism in the interstellar medium. In this work, thermal rate coefficients for the H3+ + CO and D3+ + CO reactions are calculated using ring-polymer molecular dynamics (RPMD) on a high-level machine-learning potential energy surface. The RPMD results agree well with the classical molecular dynamics results, where nuclear quantum effects are completely ignored, whereas the agreement between the RPMD results and the previous quasi-classical trajectory is good only at low temperatures. The calculated [HCO+]/[HOC+] product branching ratios decrease as the temperature increases, and the product branching is exclusively determined by the initial collisional orientation, which governs the formation of an ion-dipole complex, H3+···CO or H3+···OC, that dissociates into H2 + HCO+ or H2 + HOC+, respectively, via a direct mechanism. However, the contribution of the indirect mechanism via the rearrangement between H3+···CO and H3+···OC increases as the temperature increases, although its absolute fraction is small.