Factors Determining the Selectivity of NO Reduction Catalyzed by Copper-Vanadium Oxide Cluster Anions Cu2VO3‒5.

Catalytic NO reduction by CO is imperative to satisfy the increasingly rigorous emission regulations. Identifying the structural characteristic of crucial intermediate that governs the selectivity of NO reduction is pivotal to having a fundamental understanding on real-life catalysis. Herein, benefiting from the state-of-the-art mass spectrometry, we demonstrated experimentally that the Cu2VO3-5- clusters can mediate the catalysis of NO reduction by CO, and two competitive channels to generate N2O and N2 can co-exist. Quantum-chemical calculations were performed to rationalize this selectivity. The formation of the ONNO unit on the Cu2 dimer was demonstrated to be a precursor from which two pathways of NO reduction start to emerge. In the pathway of N2O generation, only the Cu2 dimer was oxidized and the VO3 moiety  functions as a "support", while both moieties have to contribute to anchor oxygen atoms from the ONNO unit and then N2 can be generated. This finding displays a clear picture to elucidate how and why the involvement of VO3 "support" can regulate the selectivity of NO reduction.

Simple and field-adapted species identification of biological specimens combining multiplex multienzyme isothermal rapid amplification, lateral flow dipsticks, and universal primers for initial rapid screening without standard PCR laboratory.

Species identification of biological specimens can provide the valuable clues and accelerate the speed of prosecution material processing for forensic investigation, especially when the case scene is inaccessible and the physical evidence is cumbersome. Thus, establishing a rapid, simple, and field-adapted species identification method is crucial for forensic scientists, particularly as first-line technology at the crime scene for initial rapid screening. In this study, we established a new field-adapted species identification method by combining multiplex multienzyme isothermal rapid amplification (MIRA), lateral flow dipstick (LFD) system, and universal primers. Universal primers targeting COX I and COX II genes were used in multiplex MIRA-LFD system for seven species identification, and a dedicated MIRA-LFD system primer targeting CYT B gene was used to detect the human material. DNA extraction was performed by collecting DNA directly from the centrifuged supernatant. Our study found that the entire amplification process took only 15 min at 37 °C and the results of LFDs could be visually observed after 10 min. The detection sensitivity of human material could reach 10 pg, which is equivalent to the detection of single cell. Different common animal samples mixed at the ratio of 1 ng:1 ng, 10 ng:1 ng, and 1 ng:10 ng could be detected successfully. Furthermore, the damaged and degraded samples could also be detected. Therefore, the convenient, feasible, and rapid approach for species identification is suitable for popularization as first-line technology at the crime scene for initial rapid screening and provides a great convenient for forensic application.

Selective Reduction of NO into N2 Catalyzed by the RhM2O3- Clusters (M = Ta, V, and Al): Importance of the Triatomic Lewis Acid-Base-Acid Mδ+-Rhδ--Mδ+ Site.

Catalytic NO reduction by CO into N2 and CO2 is imperative owing to the increasingly rigorous emission regulation. Identifying the nature of active sites that govern the reactivity and selectivity of NO reduction is pivotal to tailor catalysts, while it is extremely challenging because of the complexity of real-life systems. Guided by our newly discovered triatomic Lewis acid-base-acid (LABA, Ceδ+-Rhδ--Ceδ+) site that accounts for the selective reduction of NO into N2 catalyzed by the RhCe2O3- cluster in gas-phase experiments, the reactivity of the RhM2O3- (M = Ta, V, and Al) clusters in catalytic NO reduction by CO was explored. We determined theoretically that the LABA site still prevails to reduce NO to N2 mediated by RhTa2O3- and RhV2O3-, and the strong M-oxygen affinity was emphasized to construct the LABA site. An overall assessment highlights that RhV2O3- functions as a more promising catalyst because the well-fitting V-O bonding strength facilitates both elementary reactions of NO reduction and CO oxidation.

CO Oxidation Promoted by NO Adsorption on RhMn2O3- Cluster Anions.

CO oxidation represents an important model reaction in the gas phase to provide a clear structure-reactivity relationship in related heterogeneous catalysis. Herein, in combination with mass spectrometry experiments and quantum-chemical calculations, we identified that the RhMn2O3- cluster cannot oxidize CO into gas-phase CO2 at room temperature, while the NO preadsorbed products RhMn2O3-[(NO)1,2] are highly reactive in CO oxidation. This discovery is helpful to get a fundamental understanding on the reaction behavior in real-world three-way catalytic conditions where different kinds of reactants coexist. Theoretical calculations were performed to rationalize the crucial roles of preadsorbed NO where the strongly attached NO on the Rh atom can greatly stabilize the products RhMn2O2-[(NO)1,2] during CO oxidation and at the same time works together with the Rh atom to store electrons that stay originally in the attached CO2- unit. The leading result is that the desorption of CO2, which is the rate-determining step of CO oxidation by RhMn2O3-, can be greatly facilitated on the reactions of RhMn2O3-[(NO)1,2] with CO.

Selective Reduction of NO into N2 Catalyzed by Rh1-Doped Cluster Anions RhCe2O3-5.

Catalytic conversion of toxic nitrogen oxide (NO) and carbon monoxide (CO) into nitrogen (N2) and carbon dioxide (CO2) is imperative under the weight of the increasingly stringent emission regulations, while a fundamental understanding of the nature of the active site to selectively drive N2 generation is elusive. Herein, in combination with state-of-the-art mass-spectrometric experiments and quantum-chemical calculations, we demonstrated that the rhodium-cerium oxide clusters RhCe2O3-5- can catalytically drive NO reduction by CO and give rise to N2 and CO2. This finding represents a sharp improvement in cluster science where N2O is commonly produced in the rarely established examples of catalytic NO reduction mediated with gas-phase clusters. We demonstrated the importance of the unique chemical environment in the RhCe2O3- cluster to guide the substantially improved N2 selectivity: a triatomic Lewis "acid-base-acid" Ceδ+-Rhδ--Ceδ+ site is proposed to strongly adsorb two NO molecules as well as the N2O intermediate that is attached on the Rh atom and can facilely dissociate to form N2 assisted by both Ce atoms.

Catalytic NO Reduction by NO Pre-Adsorbed RhCeO2 NO- Clusters.

A fundamental understanding on the dynamically structural evolution of catalysts induced by reactant gases under working conditions is challenging but pivotal in catalyst design. Herein, in combination with state-of-the-art mass spectrometry for cluster reactions, cryogenic photoelectron imaging spectroscopy, and quantum-chemical calculations, we identified that NO adsorption on rhodium-cerium bimetallic oxide cluster RhCeO2 - can create a Ce3+ ion in product RhCeO2 NO- that serves as the starting point to trigger the catalysis of NO reduction by CO. Theoretical calculations substantiated that the reduction of another two NO molecules into N2 O takes place exclusively on the Ce3+ ion while Rh behaves like a promoter to buffer electrons and cooperates with Ce3+ to drive NO reduction. Our finding demonstrates the importance of NO in regulating the catalytic behavior of Rh under reaction conditions and provides much-needed insights into the essence of NO reduction over Rh/CeO2 , one of the most efficient components in three-way catalysts for NOx removal.

Magnetic bead-based separation of sperm cells from semen-vaginal fluid mixed stains using an anti-ACRBP antibody.

Forensic DNA analysis of semen-vaginal fluid mixed stains is essential and necessary in sexual assault cases. Here, we used a magnetic bead conjugated acrosin binding protein (ACRBP) antibody to separate and enrich sperm cells from mixed stains. Previously, western blotting indicated that ACRBP was specifically expressed in sperm cells, but not in female blood and epithelial cells, while immunofluorescence data showed ACRBP was localized to the acrosome in sperm cells. In our study, sperm were separated from mixed samples at three sperm cell/female buccal epithelial cell ratios (103:103; 103:104; and 103:105) using a magnetic bead conjugated ACRBP antibody. Subsequently, 23 autosomal short tandem repeat (STR) loci were amplified using the Huaxia™ Platinum PCR Amplification System and genotyped using capillary electrophoresis. The genotyping success rate for STR loci was 90% when the sperm to female buccal epithelial cell ratio was > 1:100 in mixed samples. Our results suggest that the magnetic bead conjugated ACRBP antibody is effective for isolating sperm cells in sexual assault cases.

Gas-phase reactions driven by polarized metal-metal bonding in atomic clusters.

Multimetallic catalysts exhibit great potential in the activation and catalytic transformation of small molecules. The polarized metal-metal bonds have been gradually recognized to account for the reactivity of multimetallic catalysts due to the synergistic effect of different metal centers. Gas-phase reactions on atomic clusters that compositionally resemble the active sites on related condensed-phase catalysts provide a widely accepted strategy to clarify the nature of polarized metal-metal bonds and the mechanistic details of elementary steps involved in the catalysis driven by this unique chemical bonding. This perspective review concerns the progress in the fundamental understanding of industrially and environmentally important reactions that are closely related to the polarized metal-metal bonds in clusters at a strictly molecular level. The following topics have been summarized and discussed: (1) catalytic CO oxidation with O2, H2O, and NO as oxidants (2) and the activation of other inert molecules (e.g., CH4, CO2, and N2) mediated with clusters featuring polarized metal-metal bonding. It turns out that the findings in the gas phase parallel the catalytic behaviors of condensed-phase catalysts and the knowledge can prove to be essential in inspiring future design of promising catalysts.

Reverse water-gas shift reaction catalyzed by diatomic rhodium anions.

The reverse water-gas shift (RWGS, CO2 + H2 → CO + H2O, ΔH298 = +0.44 eV) reaction mediated by the diatomic anion Rh2- was successfully constructed. The generation of a gas-phase H2O molecule and ion product [Rh2(CO)ads]- was identified unambiguously at room temperature and the only elementary step that requires extra energy to complete the catalysis is the desorption of CO from [Rh2(CO)ads]-. This experimentally identified Rh2- anion represents the first gas-phase species that can drive the RWGS reaction because it is challenging to design effective routes to yield H2O from CO2 and H2. The reactions were performed by using our newly developed double ion trap reactors and characterized by mass spectrometry, photoelectron spectroscopy, and high-level quantum-chemical calculations. We found that the order that the reactants (CO2 or D2) were fed into the reactor did not have a pronounced impact on the reactivity and the final product distribution (D2O and Rh2CO-). The atomically precise insights into the key steps to guide the reaction toward the RWGS direction were provided.

Facile CO bond cleavage on polynuclear vanadium nitride clusters V4N5.

Identifying the structural configurations of precursors for CO dissociation is fundamentally interesting and industrially important in the fields of, e.g., Fischer-Tropsch synthesis. Herein, we demonstrated that CO could be dissociated on polynuclear vanadium nitride V4N5- clusters at room temperature, and a key intermediate, with CO in a N-assisted tilted bridge coordination where the C-O bond ruptures easily, was discovered. The reaction was characterized by mass spectrometry, photoelectron spectroscopy, and quantum-chemistry calculations, and the nature of the adsorbed CO on product V4N5CO- was further characterized by a collision-induced dissociation experiment. Theoretical analysis evidences that CO dissociation is predominantly governed by the low-coordinated V and N atoms on the (V3N4)VN- cluster and the V3N4 moiety resembles a support. This finding strongly suggests that a novel mode for facile CO dissociation was identified in a gas-phase cluster study.

Water-Gas Shift Catalyzed by Iridium-Vanadium Oxide Clusters IrVO2- with Iridium in a Rare Oxidation State of -II.

The discovery of compounds containing transition metals with an unusual and well-established oxidation state is vital to enrich our horizon on formal oxidation state. Herein, benefiting from the study of the water-gas shift reaction (CO + H2O → CO2 + H2) mediated with the iridium-vanadium oxide cluster IrVO2-, the missing -II oxidation state of iridium was identified. The reactions were performed by using our newly developed double ion trap reactors that can spatially separate the addition of reactants and are characterized by mass spectrometry and quantum-chemical calculations. This finding makes an important step that all the proposed 13 oxidation states of iridium (+IX to -III) have been known. The iridium atom in the IrVO2- cluster features the Ir═V double bond and resembles chemically the coordinated oxygen atom. A reactivity study demonstrated that the flexible role switch of iridium between an oxygen-atom like (Ir-IIVO2-) and a transition-metal-atom like behavior (Ir+IIVO3-) in different species can drive the water-gas shift reaction in the gas phase under ambient conditions. This result parallels and well rationalizes the extraordinary reactivity of oxide-supported iridium single-atom catalysts in related condensed-phase reactions.

Pharmacokinetic evaluation and relative bioavailability pilot study of fidaxomicin in healthy Chinese subjects: An open, randomized, single-dose, cross-over study.

OBJECTIVE: To compare the pharmacokinetic (PK) characteristics, investigate relative bioavailability, and provide data for potential additional bioequivalence trials between generic fidaxomicin (test (T) formulation) and the original brand (reference (R) formulation) in healthy Chinese subjects. MATERIALS AND METHODS: An open, randomized, single-dose, cross-over study was conducted in 18 healthy Chinese subjects. The subjects randomly received T or R formulations and the alternative formulations were received after a 14-day wash-out period. Blood and fecal samples were collected and tested by liquid chromatography-tandem mass spectrometry (LC-MS/MS). PK parameters were calculated using a non-compartmental model. Relative bioavailability considering commonly established bioequivalence criteria was assessed. RESULTS: Cmax were 3.58 ± 2.74 ng/mL and 6.01 ± 3.93 ng/mL, and AUC0-∞ were 35.71 ± 18.68 h×ng/mL and 52.15 ± 31.31 h×ng/mL for the T and R formulations, respectively. The tmax of both formulations was 5.00 hours. The cumulative fecal excretion rate (Fe0-96h/F) of fidaxomicin and its main active metabolite OP-1118 were similar for both formulations. The geometric mean ratios and 90% confidence intervals (CI) of AUC0-t, AUC0-∞, and Cmax were not completely within the range of 80.00 - 125.00%. Significant within-subject and inter-subject coefficients of variation (> 30%) were found. CONCLUSION: Despite the differences in exposure, PK characteristics and fecal recovery of the two formulations were similar, suggesting that an effective concentration of the generic fidaxomicin could be achieved locally in the gastrointestinal tract. Fidaxomicin was a highly viable drug, thus providing reference for future clinical study design.

Activation of Carbon Dioxide by CoCDn- (n = 0-4) Anions.

Laser ablation generated CoCDn- (n = 0-4) anions were mass selected and then reacted with CO2 in an ion trap reactor. The reactions were characterized by mass spectrometry and quantum chemical calculations. The experimental results demonstrated that the CoC- anion can convert CO2 into CO. In contrast, the bare Co- anion is inert toward CO2. Coordinated D ligands can modify the reactivity of CoCD1-4- in which CoCD1-3- can reduce CO2 into CO selectively and CoCD4- can only adsorb CO2. The crucial roles of the coordinated C and D ligands to tune the reactivity of CoCDn- (n = 0-4) toward CO2 were rationalized by theoretical calculations. Note that the hydrogenation process that is usually observed in the reactions of gas-phase metal hydrides with CO2 is completely suppressed for the reactions CoCDn- + CO2. This study provides insights into the molecular-level origin for the observations that CO can be selectively generated from CO2 catalyzed by cobalt-containing carbides in heterogeneous catalysis.

Homeobox C4 promotes hepatocellular carcinoma progression by the transactivation of Snail.

Homeobox C4 (HOXC4) belongs to the homeoprotein family of transcription factors, which play a critical role in morphogenesis and differentiation during embryonic development. Aberrant expression of HOXC4 has been reported in several types of cancers. However, the role of HOXC4 in hepatocellular carcinoma (HCC) remains unknown. Here, we reported that HOXC4 is upregulated in HCC tissues and predicts a poor outcome in patients with HCC. HOXC4 promotes HCC progression and induces an EMT-like phenotype both in vitro and in vivo. Furthermore, we demonstrated that the EMT-related transcription factor Snail is a transcriptional target of HOXC4 and HOXC4 regulates EMT by regulation of transforming growth factor ß (TGF-ß) signaling in HCC. Together, our study suggests that HOXC4 as a novel potential therapeutic target for HCC therapy.

Investigation of control region sequences of mtDNA in Naqu Tibetan population from Northwestern China.

BACKGROUND: The sequence polymorphisms of mitochondrial DNA (mtDNA) are valuable in forensic medicine and anthropological genetics. AIM: We analysed the sequences of the mtDNA control region in 207 unrelated Tibetan individuals from the Naqu region, Tibet Autonomous Region in the People's Republic of China, and investigated the population structure of the region by population comparison with other groups. SUBJECTS AND METHODS: Genomic DNA was extracted and hypervariable regions (HVS-I and HVS-II) were amplified and sequenced. Subsequently, sequences were aligned and compared with the revised Cambridge sequence. Moreover, population comparison was performed between the Naqu Tibetan group and the other groups. CONCLUSION: Our study provided available data for exploring the mtDNA haplotype of the Tibetan population in the Naqu region, and population comparisons found that the Naqu Tibetan population has its own unique structure.

No association between the Ser9Gly polymorphism of the dopamine receptor D3 gene and schizophrenia: a meta-analysis of family-based association studies.

BACKGROUND: Previous studies found that Ser9Gly (rs6280) might be involved in the occurrence of schizophrenia. However, no consist conclusion has yet been achieved. Compared to the case-control study, the family-based study took into account stratification bias. Thus, we conducted a meta-analysis of family-based studies to measure a pooled effect size of the association between Ser9Gly and the risk of schizophrenia. METHODS: The relevant family-based studies were screened using the electronic databases by the inclusion criteria. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to measure the correction between Ser9Gly polymorphism and schizophrenia susceptibility. Subgroup analysis was performed by stratification of ethnicity (i.e., East Asian, Caucasian, and other populations). Additionally, publication bias was evaluated by the funnel plot. RESULTS: After literature searching, a total of 13 family-based association studies were included, which contained 11 transmission disequilibrium test (TDT) studies with 1219 informative meiosis and 5 haplotype-based haplotype relative risk (HRR) studies. No statistical significance of the heterogeneity was detected in TDT and HRR studies. Thus, the pooled effect size was calculated under the fixed effect model. The results found that the association was significantly protective in East Asian in TDT studies (204 informative meiosis, OR = 0.744, 95% CI = 0.564-0.980, Z-value = - 2.104, p = 0.035). CONCLUSIONS: The meta-analysis based on the family study found a protective association of Ser9Gly in East Asian. In future, large sample molecular epidemiology studies are needed to validate our findings.

Catalytic CO Oxidation by O2 Mediated with Single Gold Atom Doped Titanium Oxide Cluster Anions AuTi2 O4-6.

Gas-phase studies on catalytic CO oxidation by O2 mediated with gold-containing heteronuclear metal oxide clusters are vital to obtain the structure-reactivity relationship of supported gold catalysts, while it is challenging to trigger the reactivity of clusters with closed-shell electronic structure in O2 activation. Herein, we identified that CO oxidation by O2 can be catalyzed by the AuTi2 O4-6- clusters, among which AuTi2 O4- with closed-shell electronic structure can effectively activate O2 . The reactions were characterized by mass spectrometry and quantum chemical calculations. Theoretical calculations showed that in the initial stage of O2 activation, the Ti2 O4 moiety in AuTi2 O4- contributes dominantly to activate O2 into superoxide (O2- ⋅) without participation of the Au atom. In subsequent steps, the intimate charge transfer interaction between Au and the Ti2 O4 moiety drives the direct dissociation of the O2- ⋅ unit.

Reactivity of Iron Hydride Anions Fe2Hn- (n = 0-3) with Carbon Dioxide.

The hydrogenation of CO2 into value-added complexes is of great importance for both environmental and economic issues. Metal hydrides are good models for the active sites to explore the nature of CO2 hydrogenation; however, the fundamental insights into C-H bond formation are still far from clear because of the complexity of real-life catalysts. Herein, gas-phase reactions of the Fe2Hn- (n = 0-3) anions with CO2 were investigated using mass spectrometry and quantum chemical calculations. The experimental results showed that the reduction of CO2 into CO dominates all of these reactions, whereas Fe2H- and Fe2H2- can induce the hydrogenation of CO2 effectively to give rise to products Fe(HCO2)- and HFe(HCO2)-, respectively. The mechanistic aspects and the reactivity of Fe2Hn- with an increased number of H atoms in CO2 hydrogenation were rationalized by theoretical calculations.

Genetic structure and forensic characteristics of the Korean population revealed by GoldenEye 20A.

BACKGROUND: In China, most Koreans live in the Northeast, including Jilin (59.64%), Heilongjiang (20.21%), and Liaoning (12.55%) provinces, while the rest are spread to other parts of China. Koreans across China share a common culture, which is similar to Korea. AIM: The Combined DNA Index System or CODIS has been increased from thirteen to twenty loci, so it is important to generate improved profiles with the help of these additional loci. SUBJECTS AND METHODS: In the current study we have analysed 564 unrelated individuals from the Yanbian Korean population using the GoldenEyeTM 20 A kit (Beijing PeopleSpot Inc). Allelic frequencies, population comparisons and forensic statistical parameters of commonly used short tandem repeats were calculated for the Yanbian Korean population from Jilin province, P.R. China. RESULTS: A total of 232 alleles were observed and all the loci were found to be in Hardy-Weinberg equilibrium after Bonferroni correction. The combined power of discrimination was 99. 999999999999999999999913% and the combined power of exclusion was 0.999999995349261. CONCLUSION: Phylogenetic parameters showed that the Yanbian Koreans living in Jilin had the closest genetic relationship with South Koreans and other East Asian populations. The present study provides a precise reference database of Jilin Koreans for forensic applications and studies of population genetics.

Neutral Au1-Doped Cluster Catalysts AuTi2O3-6 for CO Oxidation by O2.

Oxide supported gold catalysts (e.g., Au/TiO2) are of great significance in heterogeneous catalysis owing to their extraordinary catalytic activity. Study of heteronuclear metal oxide clusters (HMOCs, e.g., Au xTi yO z q) is an important way to uncover the molecular-level mechanisms of gold catalysis in the related heterogeneous catalytic systems. However, the current studies of HMOCs are focused on charged clusters with little attention paid to neutral species. The reactivity study of neutral HMOCs is vital to have a comprehensive understanding of heterogeneous catalysis, but it is experimentally challenging because of the difficulty of cluster ionization and detection without fragmentation. Herein, benefiting from a homemade time-of-flight mass spectrometer coupled with a vacuum ultraviolet laser system, the reactivity of neutral Au1-doped titanium oxide clusters AuTi2O3-6 in catalytic CO oxidation by O2 has been successfully identified. The mechanistic details of the catalysis have been elucidated by quantum chemistry calculations. The crucial roles of the mobile AuCO species that can facilitate not only the process of CO oxidation but also the process of O2 activation have been discovered in the cluster catalysis. The fascinating results are of substantial importance to understand the mechanisms of CO oxidation over Au/TiO2, one type of the best studied gold catalysts.