ABSTRACT
Gas-phase reactions of iridium cluster cations, Irn+ (n = 1-8), with ammonia are studied at near-thermal energies. In single collision reactions, dehydrogenation of NH3 proceeds at n = 1-5, and in particular, Ir4+ and Ir5+ are found to be significantly reactive. This size dependence is quite different from those of other platinum group metal cluster cations, where usually only the dimers are able to dehydrogenate NH3. Moreover, the sequentially dehydrogenated products, Ir4,5(NH)m+ (m = 2-5), are chiefly observed under multiple collision conditions. This observation suggests that the NH species on Ir4,5+ possibly encourages, or at least does not prohibit, the adsorption of the coming NH3 molecule and the dehydrogenation.
ABSTRACT
Gas-phase reactions of tungsten carbide and nitride cluster cations, WnCm+ (n = 1-5, m ≤ 5) and WnNm+ (n = 1-6, m ≤ 2), with methane are investigated at near thermal energies. Most of the clusters react readily with CH4 to form WnCm+1H2+ or WnNmCH2+ under single collision conditions, in contrast to the almost no reactivity of pure tungsten clusters. This result indicates that the introduction of carbon or nitrogen atoms can enhance the reactivity of tungsten clusters toward the CH4 dehydrogenation. In addition, the formation and the release of an ethylene molecule are strongly suggested in the reaction of WC+ with CH4 as a minor reaction channel. Nearly all the nitride cluster cations, WnNm+ (n ≥ 2), exhibit higher reactivity than their corresponding carbides, WnCm+, whereas WN+ is less reactive than WC+. Furthermore, the multiple collision reactions of the highly reactive tungsten nitride species such as WN+ and W4N+ lead to the formation of WnNmCxH2x+ (x = 2, 3), which shows that the dehydrogenation of more than one CH4 molecule occurs.
ABSTRACT
Intellectual disability (ID) is a clinically and genetically heterogeneous developmental brain disorder. The present study describes two male siblings, aged 7 and 1 yr old, with severe ID, spastic quadriplegia, nystagmus, and brain atrophy with acquired microcephaly. We used the exome sequencing to identify the causative gene in the patients and identified a hemizygous missense variant, c.1282T>A (p.W428R), in the p21-activated serine/threonine kinase 3 gene (PAK3), which is associated with X-linked ID. p.W428R is located within the highly conserved kinase domain and was predicted to induce loss of enzymatic function by three mutation prediction tools (SIFT, PolyPhen-2, and MutationTaster). In addition, this variant has not been reported in public databases (as of the middle of December 2018) or in the data from 3275 individuals of the Japanese general population analyzed using high-depth whole-genome sequencing. To date, only 13 point mutations and deletions in PAK3 in ID have been reported. The literature review illustrated a phenotypic spectrum of PAK3 pathogenic variant, and our cases represented the most severe form of the PAK3-associated phenotypes. This is the first report of a PAK3 pathogenic variant in Japanese patients with X-linked ID.
Subject(s)
Mental Retardation, X-Linked/genetics , p21-Activated Kinases/genetics , Child , Developmental Disabilities/genetics , Exome , Genes, X-Linked/genetics , Genetic Association Studies , Humans , Infant , Intellectual Disability/genetics , Intellectual Disability/metabolism , Japan , Male , Mental Retardation, X-Linked/metabolism , Microcephaly/genetics , Mutation , Mutation, Missense/genetics , Pedigree , Phenotype , Siblings , Exome Sequencing/methods , p21-Activated Kinases/metabolismABSTRACT
Gas-phase reactivity of pure and partially oxidized tungsten atomic and cluster cations, Wn+ (n = 1-6) and WnOm+ (n = 1-5, m ≤ 6), with methane is studied at the collision energies from 0.1 to 1.0 eV under single collision conditions. The dehydrogenation of CH4 (i.e., the release of H2) is observed for most of WnOm+, whereas Wn+ (n ≥ 2) are almost unreactive. This result indicates that the reactivity of tungsten clusters can be enhanced by the addition of oxygen atoms. Moreover, the reaction cross section of WnOm+ strongly depends on the cluster composition, and some clusters such as W2O3+, W3O+, W3O5+, and W5O3+ exhibit high reactivity. It turns out that the reactivity of these clusters is roughly comparable to that of the typical platinum cluster cations, which are one of the most reactive clusters toward methane dehydrogenation. The reactivity of Wn+ and WnOm+ toward CH4 can be explained by a simple model of their orbital energies and the potential energy diagrams obtained by using the density functional theory calculations. The calculations also suggest that the oxygen atom(s) in WnOm+ is like a spectator and the formation of a hydroxyl group is not necessary for the cleavage of C-H bonds in CH4.
ABSTRACT
PIEZO2 encodes a mechanically activated cation channel, which is abundantly expressed in dorsal root ganglion neuron and sensory endings of proprioceptors required for light touch sensation and proprioception in mice. Biallelic loss-of-function mutations in PIEZO2 (i.e., PIEZO2 deficiency) were recently found to cause an arthrogryposis syndrome. Sixteen patients from eight families have been reported to date. Herein we report a new case, including detailed clinical characteristics and courses as well as comprehensive neurological features. The patient was a 12-year-old girl presenting with congenital multiple contractures, progressive severe scoliosis, prenatal-onset growth impairment, motor developmental delay with hypotonia and myopathy-like muscle pathology, mild facial features, and normal intelligence. Her neurological features included areflexia, impaired proprioception, and decreased senses. Neurophysiological examination revealed decreased amplitude of sensory nerve action potentials, absent H reflex, and prolongation of central conduction times. Clinical exome sequencing revealed a novel homozygous frameshift mutation in PIEZO2 (NM_022068: c.4171_4174delGTCA: p.Val1391Lysfs*39) with no detectable mRNA expression of the gene. PIEZO2 deficiency represents a clinical entity involving characteristic neuromuscular abnormalities and physical features. Next generation sequencing-based comprehensive molecular screening and extensive neurophysiological examination could be valuable for diagnosis of the disorder.
Subject(s)
Arthrogryposis/diagnosis , Arthrogryposis/genetics , Genetic Association Studies , Genetic Predisposition to Disease , Ion Channels/deficiency , Phenotype , Child , Electromyography , Facies , Female , Gene Expression , Genetic Association Studies/methods , Genotype , High-Throughput Nucleotide Sequencing , Humans , Mutation , Nonsense Mediated mRNA Decay , Sequence Analysis, DNA , SyndromeABSTRACT
BACKGROUND: Because subcutaneously injected hyaluronic acid filler is absorbed over 6 months to 1 year after the treatment of facial wrinkles, frequent retreatment may be required. However, persistent long-term effects are often clinically observed when hyaluronic acid filler is injected as a bolus for facial augmentation. Therefore, the authors investigated, over time, the changes in volume and histologic features of subcutaneous bolus injections of hyaluronic acid. METHODS: Hyaluronic acid filler was subcutaneously injected as a bolus into the dorsum of 6-week-old rats. At several time points (immediately after injection and 4, 8, 16, 32, and 64 weeks thereafter), magnetic resonance imaging was introduced to observe morphologic changes and to measure volume. Histologic examination of sectioned tissues was also performed. RESULTS: The average volume increased for up to 4 weeks after injection and then gradually decreased, with 74.8 percent of the injected volume remaining after 64 weeks, with no statistical difference compared to the initial volume. Histologic analysis revealed that lattice structures were created by fibroblasts and collagen fibers, and blood vessels and adipocytes were also generated in the filler. CONCLUSIONS: Although subcutaneous bolus injections of hyaluronic acid filler exhibited flattening, the total volume was maintained even after 64 weeks. Histologically, hyaluronic acid filler acted as a scaffold for autogenous tissue replacement by means of fibroblast migration and proliferation, collagen induction, and angiogenesis, followed by proliferation of adipocytes. This study demonstrates that the total volume is maintained long-term by replacing part of the injected hyaluronic acid filler with autologous tissues.
Subject(s)
Dermal Fillers/pharmacology , Hyaluronic Acid/pharmacology , Subcutaneous Tissue/drug effects , Animals , Cosmetic Techniques , Dermal Fillers/administration & dosage , Female , Hyaluronic Acid/administration & dosage , Injections, Subcutaneous , Kinetics , Rats , Rats, Inbred F344 , Subcutaneous Tissue/metabolism , Subcutaneous Tissue/pathologyABSTRACT
Reactions of copper oxide cluster cations, Cu nO m+ ( n = 3-7; m ≤ 5), with ammonia, NH3, are studied at near thermal energies using a guided ion beam tandem mass spectrometer. The single-collision reactions of specific clusters such as Cu4O2+, Cu5O3+, Cu6O3+, Cu7O3+, and Cu7O4+ give rise to the release of H2O after NH3 adsorption efficiently and result in the formation of Cu nO m-1NH+. These Cu nO m+ clusters commonly have Cu average oxidation numbers of 1.0-1.4. On the other hand, the formation of Cu nO m-1H2+, i.e., the release of HNO, is dominantly observed for Cu7O5+ with a higher Cu oxidation number. Density functional theory calculations are performed for the reaction Cu5O3+ + NH3 â Cu5O2NH+ + H2O as a typical example of H2O release. The calculations show that this reaction occurs almost thermoneutrally, consistent with the experimental observation. Further, our experimental studies indicate that the multiple-collision reactions of Cu5O3+ and Cu7O4+ with NH3 lead to the production of Cu5+ and Cu7O+, respectively. This suggests that the desirable NH3 oxidation to N2 and H2O proceeds on these clusters.
ABSTRACT
OBJECTIVE: The aim of this study was to determine the prognostic factors for acute encephalopathy with reduced diffusion (AED) during the acute phase through retrospective case evaluation. METHODS: The participants included 23 patients with AED. The diagnosis of AED was based on their clinical course and radiological findings. We divided the patients into severe and non-severe groups based on the neurodevelopmental outcome. The severe group included seven patients (median age, 21â¯months; range, 6-87â¯months) and the non-severe group included 16 patients (19â¯months, 9-58â¯months). Clinical symptoms, laboratory data and electroencephalogram (EEG) findings within 48â¯h from the initial seizure onset were compared between the two groups to identify neurological outcome predictors. RESULTS: The incidence of coma 12-24â¯h after onset, serum creatinine (Cr) levels within 2â¯h after onset, maximum aspartate aminotransferase (AST) levels within 24â¯h after onset, and the rate of electrographic seizures in EEG were significantly higher in the severe group (Coma, 80%; Cr, 0.40â¯mg/dl, 0.37-0.73; AST, 363 IU/L, 104-662; electrographic seizures, 80%) than the non-severe group (Coma, 0%; Cr, 0.29â¯mg/dL, 0.19-0.45; AST, 58.5 IU/L, 30-386; electrographic seizures, 0%). CONCLUSIONS: Coma 12-24â¯h after onset, elevation of Cr levels within 2â¯h after onset, elevation of AST levels within 24â¯h after onset, and non-convulsive status epileptics (NCSE) in comatose patients were early predictors of severe AED. Patients in a coma after a febrile seizure should be checked for NCSE signs in EEG to terminate NCSE without delay.
Subject(s)
Brain Diseases/diagnosis , Biomarkers/blood , Brain/physiopathology , Brain Diseases/epidemiology , Child , Child, Preschool , Creatinine/blood , Electroencephalography , Humans , Incidence , Infant , Prognosis , Severity of Illness Index , Time FactorsABSTRACT
CASE: We report the case of a 13-year-old boy with Duchenne muscular dystrophy (DMD) who sustained bilateral femoral neck fractures associated with glucocorticoid-induced osteoporosis. Denosumab therapy for 18 months markedly improved the lumbar bone mineral density and the bone turnover markers. No fractures or complications were recorded during the treatment period. CONCLUSION: To the best of our knowledge, this is the first description of denosumab treatment for glucocorticoid-induced osteoporosis in a patient with DMD. The drug merits additional testing as an effective therapy for osteoporosis in patients with DMD.
Subject(s)
Bone Density Conservation Agents/therapeutic use , Denosumab/therapeutic use , Glucocorticoids/adverse effects , Muscular Dystrophy, Duchenne/complications , Osteoporosis , Adolescent , Alkaline Phosphatase/blood , Glucocorticoids/therapeutic use , Humans , Male , Muscular Dystrophy, Duchenne/drug therapy , Osteoporosis/chemically induced , Osteoporosis/complications , Osteoporosis/drug therapy , Parathyroid Hormone/bloodABSTRACT
Reactions of pure and doped rhodium cluster cations, RhnX+ (n = 2-6; X = Al, V, Co, Rh), with NO molecules were investigated at near-thermal energy using a guided ion beam tandem mass spectrometer. We found that the doping with Al and V increases the total reaction cross section mostly. Under single-collision conditions, Rh2X+ reacts with NO to produce Rh2N+ with release of metal monoxide, XO, whereas RhnX+ (n = 3-6) adsorb NO. For the specific clusters RhnAl+ (n = 3 and 4) and RhnV+ (n = 4-6), the NO adsorption is often accompanied by the release of one Rh atom. In addition, we examined the reactions of Rh5X+ (X = Al, V, Co, Rh) with NO under multiple-collision conditions and observed the cluster dioxide formation and the N2 release, i.e., NO decomposition. Particularly, the V-doping is most effective for the NO decomposition. One possible explanation for the present results is that the formation of a stable dopant metal-oxygen bond directly leads to the increase of NO dissociative adsorption energy and the reduction of the energy barrier between the molecular and dissociative adsorption, thereby encouraging the NO decomposition on the small RhnX+ clusters studied.
ABSTRACT
OBJECTIVES: Absorbable plates are sometimes grafted for treating orbital fractures. These plates cannot be readily processed to fit the shape of the fracture site, particularly when the fracture encompasses a broad area from the medial toward the inferior wall. Preparing the plates in a standard shape beforehand will be useful. Thus, in this study, the authors measured the orbital wall distance in healthy orbits to determine the mean orbital size with the ultimate goal of developing and clinically applying a standard plate for orbital fracture. METHODS: Measurements were performed for the left eye orbit on computed tomography images using a three-dimensional medical image processing workstation. The authors measured the orbital wall distances and angle of healthy orbits in 40 males and 40 females to determine the mean size of the orbit. RESULTS: In healthy orbits, no significant difference was noticeable in the angle between medial wall and inferior wall between males and females. The medial, inferior, and medial + inferior wall distances were markedly longer in males than in females (Pâ<â0.05). DISCUSSIONS: The orbital shapes had the same pattern in males and females. The standard plate would be adaptable to all cases if it were produced with the medial wall + inferior wall distance greater than the maximum value in males and trimmed to fit the orbit form of the patient. CONCLUSIONS: The results would be the basis of creating a standard plate and using it after appropriate adjustments.
Subject(s)
Bone Plates , Fracture Fixation, Internal/methods , Imaging, Three-Dimensional/methods , Orbit/surgery , Orbital Fractures/surgery , Tomography, X-Ray Computed/methods , Adolescent , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Orbit/diagnostic imaging , Orbital Fractures/diagnosis , Young AdultABSTRACT
Reactions of copper cluster cations doped with an early transition metal atom, CunTi(+) (n = 4-15) and CunV(+) (n = 5-14, 16), with NO and O2 were investigated at a near-thermal collision energy using a guided ion beam tandem mass spectrometer. Most of the clusters adsorb NO and O2 under single collision conditions, and this reaction is often followed by the release of Cu atoms. For both Ti- and V-doped Cu clusters, the total cross sections for the reaction with NO increase gradually with the cluster size up to n ≈ 11 and then decrease rapidly, whereas those with O2 are almost constant in n ≤ 12 and then decrease. The size dependence of the reactivity toward NO is found to correlate with that of the adsorption energy calculated by the density functional theory method; CunTi(+) clusters exhibit the larger reaction cross sections when they have the larger adsorption energies. The calculations of CunTi(+) also show that a structural transition from a Ti-exposed structure to Ti-encapsulated one occurs around n = 12. This indicates that a geometric property of the clusters, i.e., the position of the dopant atom, is a determining factor of reactivity. In addition, the Ti- and V-doping dramatically improves the reactivity of Cu cluster cations toward NO but it does not affect that toward O2 significantly. As a result, most of the Ti- and V-doped Cu clusters are more reactive toward NO than toward O2. We also studied the multiple-collision reaction of Cu7Ti(+) with NO and obtained the cluster dioxide, Cu3TiO2(+), as a product ion, which suggests that the dissociation of NO and the subsequent formation/release of N2 take place.
ABSTRACT
Cerebellar atrophy is recognized in various types of childhood neurological disorders with clinical and genetic heterogeneity. Genetic analyses such as whole exome sequencing are useful for elucidating the genetic basis of these conditions. Pathological recessive mutations in Sep (O-phosphoserine) tRNA:Sec (selenocysteine) tRNA synthase (SEPSECS) have been reported in a total of 11 patients with pontocerebellar hypoplasia type 2, progressive cerebellocerebral atrophy or progressive encephalopathy, yet detailed clinical features are limited to only four patients. We identified two new families with progressive cerebellar atrophy, and by whole exome sequencing detected biallelic SEPSECS mutations: c.356A>G (p.Asn119Ser) and c.77delG (p.Arg26Profs*42) in family 1, and c.356A>G (p.Asn119Ser) and c.467G>A (p.Arg156Gln) in family 2. Their development was slightly delayed regardless of normal brain magnetic resonance imaging (MRI) in infancy. The progression of clinical symptoms in these families is evidently slower than in previously reported cases, and the cerebellar atrophy milder by brain MRI, indicating that SEPSECS mutations are also involved in milder late-onset cerebellar atrophy.
Subject(s)
Alleles , Amino Acyl-tRNA Synthetases/genetics , Mutation , Olivopontocerebellar Atrophies/diagnosis , Olivopontocerebellar Atrophies/genetics , Adolescent , Amino Acid Substitution , Brain/cytology , Child , Child, Preschool , Exome , Female , Gene Frequency , Genotype , High-Throughput Nucleotide Sequencing , Humans , Infant , Magnetic Resonance Imaging , Male , Pedigree , Phenotype , Polymorphism, Single Nucleotide , Sequence Analysis, DNAABSTRACT
Two siblings born to non-consanguineous parents showed nystagmus and sudden opistotonic posturing from the early infancy, and subsequent developmental delay and marked choreiform movements with hypotonia in the childhood. The brother had a mild postnatal microcephaly. Brain MRI of the sister showed mild delay of myelination, dilated anterior horn and mild cerebellar atrophy. Whole exome sequencing (WES) revealed compound heterozygous mutations in MED17 gene in both siblings: c.1013-5A>G and c.1484T>G mutations transmitted from their father and mother, respectively. The c.1013-5A>G mutation caused insertion of 4 bases of intron 6 in the transcript, resulting in frameshift (p. Ser338Asnfs*15), and mutant transcript underwent nonsense-mediated mRNA decay in lymphoblastoid cells derived from two siblings. The c.1484T>G mutation substituted a leucine residue, which is highly conserved among the vertebrates, and was predicted to be damaging by in silico analysis programs. Both mutations were not registered in dbSNP data and in our 575 control exomes. These results suggest that the siblings' mutations are likely to be pathogenic. This is the second case report concerning MED17 mutations. Compared with the first reported cases of Caucasian Jewish origin, the clinical symptoms and courses are much milder and slower, respectively, in our cases. Genotype difference (a homozygous mutation versus compound heterozygous mutations) might explain these clinical differences between two cases, though early-onset nystagmus and later choreiform movements were unique in our cases. Clinical spectrum and phenotype-genotype correlations in this rare mutation should be further elucidated.
Subject(s)
Chorea/genetics , Chorea/physiopathology , Heterozygote , Mediator Complex/genetics , Mutation , Phenotype , Brain/pathology , Child , Chorea/pathology , DNA Mutational Analysis , Exome , Female , Humans , Magnetic Resonance Imaging , Male , SiblingsABSTRACT
Aluminum-doped copper cluster cations, CunAl(+), were produced via an ion sputtering method and analyzed by mass spectrometry. The measured size distributions show that Cu6Al(+) and Cu18Al(+) are highly stable species, which can be understood in terms of the electronic subshell 1P and 2S closings, respectively. Furthermore, the reactions of size-selected CunAl(+) (n = 4-6 and 8-16) with NO and O2 were studied at near thermal energies by using a tandem-type mass spectrometer. The doping of an Al atom improves the reactivity of the clusters toward NO in particular for n = 9, 11, 13, and 15, whereas it does not change the reactivity toward O2 significantly. Consequently, it was found that CunAl(+) (n = 9, 11, 13 and 15) are more reactive toward NO than toward O2. The high reactivity of Cu9Al(+) toward NO compared to that of Cu10(+) is explained in terms of the increase of the adsorption energy and the lowering of the barrier to dissociative adsorption, with the aid of calculations based on density functional theory. Moreover, the multiple-collision reactions of CunAl(+) (n = 9, 11, and 13) with NO result in the production of cluster dioxides, Cun-3AlO2(+), (i.e., release of N2), which clearly indicates that NO decomposition proceeds on these clusters.
ABSTRACT
Mutations in the inositol 1,4,5-triphosphate receptor type 1 gene (ITPR1) have been identified in families with early-onset spinocerebellar ataxia type 29 (SCA29) and late-onset SCA15, but have not been found in sporadic infantile-onset cerebellar ataxia. We examined if mutations of ITPR1 are also involved in sporadic infantile-onset SCA. Sixty patients with childhood-onset cerebellar atrophy of unknown etiology and their families were examined by whole-exome sequencing. We found de novo heterozygous ITPR1 missense mutations in four unrelated patients with sporadic infantile-onset, nonprogressive cerebellar ataxia. Patients displayed nystagmus, tremor, and hypotonia from very early infancy. Nonprogressive ataxia, motor delay, and mild cognitive deficits were common clinical findings. Brain magnetic resonance imaging revealed slowly progressive cerebellar atrophy. ITPR1 missense mutations cause infantile-onset cerebellar ataxia. ITPR1-related SCA includes sporadic infantile-onset cerebellar ataxia as well as SCA15 and SCA29.
Subject(s)
Genetic Predisposition to Disease/genetics , Inositol 1,4,5-Trisphosphate Receptors/genetics , Mutation, Missense/genetics , Spinocerebellar Ataxias/genetics , Brain/pathology , Child , DNA Mutational Analysis , Female , Humans , Magnetic Resonance Imaging , Male , Spinocerebellar Ataxias/pathologyABSTRACT
BACKGROUND: Injectable collagen is often used for treatment of wrinkles or scars in cosmetic surgery. However, it is degraded within a short period after subcutaneous injection. The authors aimed to achieve a long-lasting effect of the filler with a new collagenase inhibitor, esculetin (6,7-dihydroxy-2H-chromen-2-one). METHOD: Nude mice were divided into two study groups and a control group (35 mg cattle collagen): (1) those implanted with Zyderm 0.3 g subcutaneously into the dorsal region followed by daily topical application of 5% esculetin ointment (0.5 g/day) to the skin of the implanted area (the 5% esculetin ointment group), and (2) those implanted with a mixture of Zyderm 0.3 g and esculetin (1 to 4 mM) (the esculetin-mixed Zyderm groups). In each group, Zyderm was removed at different time points to measure the wet weight and hydroxyproline level. Furthermore, each removed Zyderm specimen was sectioned for histologic examination with Azan staining and immunostaining. RESULTS: In the esculetin ointment group and the 2 mM esculetin-mixed Zyderm group, the hydroxyproline levels at 30, 60, and 90 days were significantly higher than those in the control group, suggesting that esculetin suppresses the biodegradation of Zyderm. There was no significant difference in hydroxyproline level between the esculetin ointment group and the 2 mM esculetin-mixed Zyderm group; biodegradation occurred to a similar extent with either method of application. CONCLUSIONS: An atelocollagen implant is used as a safe and effective scaffold material for tissue regeneration. Future applications of the present study are expected.
Subject(s)
Collagen/pharmacology , Umbelliferones/pharmacology , Animals , Collagen/administration & dosage , Drug Combinations , Drug Interactions , Male , Mice , Mice, Nude , Ointments , Umbelliferones/administration & dosageABSTRACT
A catalytic redox reaction involving N2O and CO on size-selected copper cluster anions, Cun(-), was investigated in the gas phase using a guided ion-beam tandem mass spectrometer. When Cun(-) is exposed to a mixture of N2O and CO, CunO(-) is produced via the decomposition of N2O. Increase of the CO partial pressure results in the reproduction of Cun(-) and decrease of CunO(-) through the oxidation of CO. The present results demonstrate that a full catalytic cycle for the reaction, N2O + CO â N2 + CO2, takes place on copper cluster anions. Furthermore, in the investigations of the elementary reactions of Cun(-) + N2O and CunO(-) + CO, we found that the catalytic oxidation of CO with N2O on Cun(-) proceeds most efficiently at n = 7 in the size range of n = 5-16.
ABSTRACT
Reactions of size-selected Cu(n)(±) and Cu(n)O(m)(±) (n = 3-19, m ≤ 9) clusters with NO were investigated in the near-thermal energy region under single collision conditions using a tandem-type mass spectrometer with two ion-guided cells. Oxygen atoms preadsorbed on the cluster can significantly enhance the NO adsorption probability and cause additional reactions. NO adsorption is observed particularly for anionic copper cluster dioxides, Cu(n)O2(-) (n ≥ 8), followed by the release of a Cu atom from Cu(n)O2(-) (n = 8, 10, and 12), which suggests that NO adsorbs strongly, i.e., dissociatively on these clusters. Density functional theory calculations support that dissociative adsorption of NO occurs in the reaction of Cu8O2(-) under the present experimental conditions. On the other hand, NO oxidation proceeds in reactions of oxygen-rich cluster cations such as Cu4O3(+), Cu6O5(+), Cu9O7(+), and Cu11O8(+).