The Antagonistic Gene Paralogs Upf3a and Upf3b Govern Nonsense-Mediated RNA Decay.

Gene duplication is a major evolutionary force driving adaptation and speciation, as it allows for the acquisition of new functions and can augment or diversify existing functions. Here, we report a gene duplication event that yielded another outcome--the generation of antagonistic functions. One product of this duplication event--UPF3B--is critical for the nonsense-mediated RNA decay (NMD) pathway, while its autosomal counterpart--UPF3A--encodes an enigmatic protein previously shown to have trace NMD activity. Using loss-of-function approaches in vitro and in vivo, we discovered that UPF3A acts primarily as a potent NMD inhibitor that stabilizes hundreds of transcripts. Evidence suggests that UPF3A acquired repressor activity through simple impairment of a critical domain, a rapid mechanism that may have been widely used in evolution. Mice conditionally lacking UPF3A exhibit "hyper" NMD and display defects in embryogenesis and gametogenesis. Our results support a model in which UPF3A serves as a molecular rheostat that directs developmental events.

Safety and efficacy of an anti-human APC antibody for prophylaxis of congenital factor deficiencies in preclinical models.

Rebalance of coagulation and anticoagulation to achieve a hemostatic effect has recently gained attention as an alternative therapeutic strategy for hemophilia. We engineered a humanized chimeric antibody, SR604, based on a previously published murine antibody, HAPC1573, which selectively blocks the anticoagulant activity of human activated protein C (APC). SR604 effectively blocked the anticoagulation activities of APC in human plasma deficient in various coagulation factors in vitro with affinities ∼60 times greater than that of HAPC1573. SR604 exhibited prophylactic and therapeutic efficacy in the tail-bleeding and knee-injury models of hemophilia A and B mice expressing human APC (humanized hemophilic mice). SR604 did not interfere with the cytoprotection and endothelial barrier function of APC, nor were there obvious toxicity effects in humanized hemophilic mice. Pharmacokinetic study showed a high bioavailability (106%) of subcutaneously injected SR604 in cynomolgus monkeys. These results demonstrate that SR604 is expected to be a safe and effective therapeutic and/or prophylactic agent with a prolonged half-life for patients with congenital factor deficiencies including hemophilia A and B.

Gut microbiota compositional profile in patients with posner-schlossman syndrome.

The cause of Posner-Schlossman syndrome (PSS) remains unknown and its frequent recurrence may eventually lead to irreversible damage of the optic nerve. The influence of immune factors in the pathophysiology of PSS is gaining more and more interest. Increasing evidence suggests that gut dysbiosis plays vital roles in a variety of neurodegenerative and immune-related diseases. However, alterations of the gut microbiota in PSS patients have not been well defined yet. In this study, 16S rRNA sequencing was used to explore the difference of gut microbiota between PSS patients and healthy controls, and the correlation between the microbiota profile and clinical features was also analyzed. Our data demonstrated a significant increase of Prevotella and Prevotellaceae, and a significant reduction of Bacteroides and Bacteroidaceae in PSS patients, and KEGG analysis showed dysfunction of gut microbiota between PSS patients and healthy controls. Interestingly, further analysis showed that the alteration of gut microbiota was correlated with the PSS attack frequency of PSS. This study demonstrated the gut microbiota compositional profile of PSS patients and speculated the risk microbiota of PSS, which is expected to provide new insights for the diagnosis and treatment of PSS.

GNAQ R183Q somatic mutation contributes to aberrant arteriovenous specification in Sturge-Weber syndrome through Notch signaling.

Episcleral vasculature malformation is a significant feature of Sturge-Weber syndrome (SWS) secondary glaucoma, the density and diameter of which are correlated with increased intraocular pressure. We previously reported that the GNAQ R183Q somatic mutation was located in the SWS episclera. However, the mechanism by which GNAQ R183Q leads to episcleral vascular malformation remains poorly understood. In this study, we investigated the correlation between GNAQ R183Q and episcleral vascular malformation via surgical specimens, human umbilical vein endothelial cells (HUVECs), and the HUVEC cell line EA.hy926. Our findings demonstrated a positive correlation between episcleral vessel diameter and the frequency of the GNAQ R183Q variant. Furthermore, the upregulation of genes from the Notch signaling pathway and abnormal coexpression of the arterial marker EphrinB2 and venous marker EphB4 were demonstrated in the scleral vasculature of SWS. Analysis of HUVECs overexpressing GNAQ R183Q in vitro confirmed the upregulation of Notch signaling and arterial markers. In addition, knocking down of Notch1 diminished the upregulation of arterial markers induced by GNAQ R183Q. Our findings strongly suggest that GNAQ R183Q leads to malformed episcleral vasculatures through Notch-induced aberrant arteriovenous specification. These insights into the molecular basis of episcleral vascular malformation will provide new pathways for the development of effective treatments for SWS secondary glaucoma.

Reactivity of cationic silver clusters with O2: a probe of interplay between clusters' geometric and electronic structures.

We explored the size-dependent reactivity of Agn+ (n = 2-22) with O2 under mild conditions and found that only a few sizes of Agn+, with even values of n = 4, 6, 12, 16, 18, and 22, are reactive. Possible structures of Agn+ (n = 2-22) were determined using a genetic algorithm with incomplete local optimizations at the DFT level, and the calculated bonding strengths of O2 on these structures are consistent with experimental observations. Analyses revealed a close relationship between the reactivity of Agn+ with O2 and its HOMO-LUMO gap: cationic silver clusters with a small HOMO-LUMO gap are reactive, which can be rationalized by the covalent character of chemical bonds between Agn+ and O2 involving their frontier orbitals. The peculiar size-dependent HOMO-LUMO gaps and reactivity with O2 correlate with the subtle interplay between the electronic configurations and geometric structures of these silver cluster cations.

Adsorption of Multiple NO Molecules on Anionic Gold Clusters: Electron Transfer and Disproportionation Enhanced by Molecular Aggregation.

The reactions of Aun- clusters with multiple nitric oxide (NO) molecules are explored at 150 K by utilizing a mini-flow-tube reactor and a time-of-flight mass spectrometer. Adsorption of multiple NO molecules is observed on most Aun-, while disproportionation reactions only occur on even-sized Aun- with n = 4, 6, 8, 20 and odd-sized ones with n = 5 and 7. Theoretical calculations reveal the geometric structures and electronic states of the products containing bimolecular and trimolecular NO units, where two NO molecules typically form dimers. Different from NO monomers that weakly interact with odd-sized Aun- and form electron-sharing covalent bonds with Au10-(D3h) and Au16-, NO dimers can extract significant charge from parent Aun-. Regarding the three NO molecules, a predilection toward condensation into trimers on even-sized Aun- is observed, while the tendency is more toward an adsorption pattern of a dimer plus a monomer on odd-sized Aun-. The NO trimers register even higher charge gain from Aun- as compared with the NO dimers, which leads to an elevated degree of activation and induces the progression of disproportionation reactions. Therefore, when considering the reaction between NO and Aun-, it appears that NO has a propensity to form dimers or trimers on Aun-. This behavior of aggregate formation substantially enhances the ability of NO to absorb negative charges from Aun- although the occurrence of disproportionate dissociation reactions is initiated only for specific sizes.

Microbial metagenomic shifts in children with acute lymphoblastic leukaemia during induction therapy and predictive biomarkers for infection.

BACKGROUND: Emerging evidence has indicated a link between the gut microbiota and acute lymphoblastic leukaemia (ALL). However, the acute changes in gut microbiota during chemotherapy and the predictive value of baseline gut microbiota in infectious complication remain largely unknown. METHODS: Faecal samples (n = 126) from children with ALL (n = 49) undergoing induction chemotherapy were collected at three timepoints, i.e., initiation of chemotherapy (baseline, T0), 7 days (T1) and 33 days (T2) after initiation of chemotherapy. Gut microbiome profile was performed via metagenomic shotgun sequencing. The bioBakery3 pipeline (Kneaddata, Metaphlan 3 and HUMAnN) was performed to assign taxonomy and functional annotations. Gut microbiome at T0 were used to predict infection during chemotherapy. RESULTS: The microbial diversities and composition changed significantly during chemotherapy, with Escherichia coli, Klebsiella pneumoniae and Bifidobacterium longum being the most prominent species. The microbial metabolic pathways were also significantly altered during chemotherapy, including the pathway of pyruvate fermentation to acetate and lactate, and assimilatory sulfate reduction pathway. The receiver operating characteristic (ROC) models based on Bifidobacterium longum at T0 could predict infectious complications during the first month of chemotherapy with the area under the curve (AUC) of 0.720. CONCLUSIONS: Our study provides new insights into the acute changes in microbial and functional characteristics in children with ALL during chemotherapy. The baseline gut microbiota could be potential biomarkers for infections during chemotherapy. TRIAL REGISTRATION: The study was approved by the Ethics Committee of Zhujiang Hospital, Southern Medical University (2021-KY-171-01) and registered on http://www.chictr.org.cn (ChiCTR2200065406, Registration Date: November 4, 2022).

Adsorption of O2 on the Preferred -O-Au Sites of Small Gold Oxide Clusters: Charge-dependent Interaction and Activation.

Decades of research have illuminated the significant roles of gold/gold oxide clusters in small molecule catalytic oxidation. However, many fundamental questions, such as the actual sites to adsorb and activate O2 and the impact of charge, remain unanswered. Here, we have utilized an improved genetic algorithm program coupled with the DFT method to systematically search for the structures of Au1-5Ox-/+/0 (x = 1-4) and calculated binding interactions between Au1-5Ox-/+/0 (x = 1-2) and O2, aiming to determine the active sites and to elucidate the impact of different charge states in gold oxide systems. The results revealed that the reactivity of all three kinds of small gold oxide clusters toward O2 is strongly site-dependent, with clusters featuring an -O-Au site exhibiting a preference for adsorption. The charges on small gold oxide clusters significantly impact the interaction strength and the activation degree of adsorbed O2: in the case of anionic cluster, the interaction between O2 and the -O-Au sites leads to a chemical reaction involving electron transfer, thereby significantly activating O2; in neutral and cationic clusters, the adsorption of O2 on their -O-Au sites can be viewed as an electrostatic interaction. Pointedly, for cationic clusters, the highly concentrated positive charge on the Au atom of the -O-Au sites can strongly adsorb but hardly activate the adsorbed O2. These results have certain reference points for understanding the gold oxide interfaces and the improved catalytic oxidation performance of gold-based systems in the presence of atomic oxygen species.

Engineering Multiple Microstructural Defects for Record-Breaking Thermoelectric Properties of Chalcopyrite Cu1- x Agx GaTe2.

Defect engineering for vacancies, holes, nano precipitates, dislocations, and strain are efficient means of suppressing lattice thermal conductivity. Multiple microstructural defects are successfully designed in Cu1- x Agx GaTe2 (0 ≤ x ≤ 0.5) solid solutions through high-ratio alloying and vibratory ball milling, to achieve ultra-low thermal conductivity and record-breaking thermoelectric performance. Extremely low total thermal conductivities of 1.28 W m-1  K-1 at 300 K and 0.40 W m-1  K-1 at 873 K for the Cu0.5 Ag0.5 GaTe2 are observed, which are ≈79% and ≈58% lower than that of the CuGaTe2 matrix. Multiple phonon scattering mechanisms are collectively responsible for the reduction of thermal conductivity in this work. On one hand, large amounts of nano precipitates and dislocations are formed via vibrating ball milling followed by the low-temperature hot press, which can enhance phonon scattering. On the other hand, the difference in atomic sizes, distorted chemical bonds, elements fluctuation, and strained domains are caused by the high substitution ratio of Ag and also function as a center for the strong phonon scattering. As a result, the Cu0.7 Ag0.3 GaTe2 exhibits a record high ZTmax of ≈1.73 at 873 K and ZTave of ≈0.69 between 300-873 K, which are the highest values of CuGaTe2 -based thermoelectric materials.

Microfluidic Investigation of the Ion-Specific Effect on Bubble Coalescence in Salt Solutions.

A microfluidic method was developed to study the ion-specific effect on bubble coalescence in salt solutions. Compared with other reported methods, microfluidics provides a more direct and accurate means of measuring bubble coalescence in salt solutions. We analyzed the coalescence time and approach velocity between bubbles and used simulation to investigate the pressure evolution during the coalescence process. The coalescence time of the three salt solutions decreased initially and then increased as the concentration of the salt solution was increased. The concentration with the shortest coalescence time is considered as the transition concentration (TC) and exhibits ion-specific. At the TC, the change in coalescence time indicates a shift in the effect of salt on bubble coalescence from facilitation to initial inhibition. Meanwhile, it can be seen that the sodium halide solutions significantly inhibit the bubble coalescence and the inhibition capability follows the order NaCl > NaBr > NaI. The results of the approach velocity show that the coalescence time decreases with increasing approach velocity, as well as the approach velocity was strongly influenced by concentration. The approach velocity undergoes a significant change at the TC. Furthermore, simulations of bubble coalescence in the microchannel indicate that the vertical pressure gradient at the center point of the bubble pairs increases as bubbles approach, driving liquid film drainage until bubble coalescence. The pressure at the center of the bubble pair reaches the maximum when the bubbles have first coalesced. It was further revealed that the concentration of the salt solution has a significant impact on the maximum pressure, as evidenced by the observed trend of decreasing pressure values with increasing concentrations.

Prognostic factors of sepsis in children with acute leukemia admitted to the pediatric intensive care unit.

OBJECTIVE: To analyze the prognostic factors of sepsis in children with acute leukemia admitted to the pediatric intensive care unit (PICU) and to compare the efficacy of different scoring systems for predicting the outcome of children. METHODS: Patients with an acute leukemia diagnosis admitted to a tertiary care university hospital PICU due to sepsis during chemotherapy between May 2015 and August 2022 were retrospectively analyzed through an electronic medical record system. RESULTS: During this period, 693 children with acute leukemia initially diagnosed were admitted to the center, and 155 (22.3%) of them were transferred to PICU due to deterioration of the disease during treatment. Total 109 (70.3%) patients were transferred to PICU due to sepsis. Here, 17 patients was excluded (prior treatment from another hospital; referring from other hospitals; discontinued treatment; incomplete medical record). Of the 92 patients studied, the mortality rate was 35.9%. Multivariate analysis revealed that remission status, lactate level, invasive mechanical ventilation (IMV), and inotropic support within 48 hours after PICU transfer were independent risk factors for PICU mortality. The pediatric sequential organ failure assessment (PSOFA) score had the greatest predictive validity for hospital mortality (area under the receiver operating characteristic curve [AUROC]: 0.83, 95% confidence intervals [CI]: 0.74-0.92), followed by the pediatric early warning score (PEWS) (0.82, 0.73-0.91) and pediatric critical illness score (PCIS) (0.79, 0.69-0.88). CONCLUSION: The mortality rate among children with acute leukemia complicated with sepsis is high after being transferred to the PICU. Various scoring systems can be used to monitor the clinical status of patients, identify sepsis early, detect critical illness, and determine the optimal time for transfer to the PICU for supportive treatment, thereby improving the prognosis of these patients.

The global minimum of Ag30: a prolate spheroidal structure predicted using a genetic algorithm with incomplete local optimizations at the DFT level.

Genetic algorithms have been widely used to explore global minimum points of atomic clusters, and their incorporation with ab initio calculations (including density functional theory methods) as local optimization approaches increases their ability to accurately locate the global minimum points on complicated potential energy surfaces. However, the local optimizations using ab initio calculations significantly increase the computational cost relative to those based on empirical or semi-empirical calculations. Herein, we develop a genetic algorithm program with an incomplete local optimization strategy at the DFT level. Using several representative clusters as test examples, this program showed high efficiency in locating their global minimum points. The low-lying isomers of Ag30 were explored using this program, and the determined global minimum is a prolate spheroidal structure. The elongated spheroidal shape causes degeneracy lifting of the free electron shells, and endows Ag30 with a large HOMO-LUMO gap. The sharp increase of silver clusters' reactivity around the sizes with 30 valence electrons observed in our previous experiments could be correlated with this theoretical figure.

Single atom alloy clusters Agn-1X- (X = Cu, Au; n = 7-20) reacting with O2: Symmetry-adapted orbital model.

Single atom alloy AgCu catalysts have attracted great attention, since doping the single Cu atom introduces narrow free-atom-like Cu 3d states in the electronic structure. These peculiar electronic states can reduce the activation energies in some reactions and offer valuable guidelines for improving catalytic performance. However, the geometric tuning effect of single Cu atoms in Ag catalysts and the structure-activity relationship of AgCu catalysts remain unclear. Here, we prepared well-resolved pristine Agn - as well as single atom alloy Agn-1Cu- and Agn-1Au- (n = 7-20) clusters and investigated their reactivity with O2. We found that replacing an Ag atom in Agn - (n = 15-18) with a Cu atom significantly increases the reactivity with O2, while replacement of an Ag with an Au atom has negligible effects. The adsorption of O2 on Agn - or Agn-1Cu- clusters follows the single electron transfer mechanism, in which the cluster activity is dependent on two descriptors, the energy level of α-HOMO (strong correlation) and the α-HOMO-LUMO gap (weak correlation). Our calculation demonstrated that the cluster arrangements caused by single Cu atom alloying would affect the above activity descriptors and, therefore, regulates clusters' chemical activity. In addition, the observed reactivity of clusters in the representative sizes with n = 17-19 can also be interpreted using the symmetry-adapted orbital model. Our work provides meaningful information to understand the chemical activities of related single-atom-alloy catalysts.

Evaluation of Schlemm's canal with swept-source optical coherence tomography in primary angle-closure disease.

PURPOSE: To perform an in vivo evaluation of the changes in Schlemm's canal (SC) among patients with primary angle-closure disease (PACD) using swept-source optical coherence tomography (SS-OCT). METHODS: Patients diagnosed with PACD who had not undergone surgery were recruited. The SS-OCT quadrants scanned herein included the nasal and temporal sections at 3 and 9 o'clock, respectively. The diameter and cross-sectional area of the SC were measured. A linear mixed-effects model was performed to analyze the effects of parameters on the SC changes. The hypothesis of interest was related to the angle status (iridotrabecular contact, ITC/open angle, OPN), which was further explored with pairwise comparisons of the estimated marginal means (EMMs) of the SC diameter and SC area. In the ITC regions, the relationship between the trabecular-iris contact length (TICL) percentage and SC parameters was also studied by a mixed model. RESULTS: A total of 49 eyes of 35 patients were included for measurements and analysis. The percentage of observable SCs in the ITC regions was only 58.5% (24/41), whereas it was 86.0% (49/57) in the OPN regions (χ2 = 9.44, p = 0.002). ITC was significantly associated with a decreasing SC size. The EMMs for the diameter and cross-sectional area of SC at the ITC and OPN regions were 203.34 µm versus 261.41 µm (p = 0.006) and 3174.43 µm2 versus 5347.63 µm2 (p = 0.022), respectively. Sex, age, spherical equivalent refraction, intraocular pressure, axial length, extent of angle closure, history of acute attack and treatment with LPI were not significantly associated with SC parameters. In the ITC regions, a larger TICL percentage was significantly associated with a decrease in SC diameter and area (p = 0.003 and 0.019, respectively). CONCLUSIONS: The morphologies of SC could be affected by the angle status (ITC/OPN) in patients with PACD, and ITC was significantly associated with a decreasing SC size. These changes in SC as described by OCT scans might help to elucidate the progression mechanisms of PACD.

Current situation and influencing factors of disease uncertainty in parents of children with Sturge‒Weber syndrome: a retrospective study.

BACKGROUND: Sturge Weber syndrome (SWS), can cause extensive capillary malformations on the face, head, trunk, and other parts of the body, and the eyes can also suffer optic nerve injury. Secondary glaucoma can cause blindness, which has the characteristics of a relatively hidden onset and unclear pathogenesis. The treatment of SWS secondary glaucoma has always been difficult, and due to the characteristics of the disease, there is uncertainty about the long-term efficacy and safety of various treatment methods for such patients. METHODS: A total of 105 parents of children with SWS completed a self-designed general information questionnaire, a generalized anxiety questionnaire (GAD-7), a patient health questionnaire (PHQ-2), a stress perception scale (PSS-4), a simple coping scale (SCSQ) and a disease-uncertainty scale (PPUS). RESULTS: The total uncertainty score of parents of children with SWS was 79.07 ± 13.24, and the average item score was 2.82 ± 0.47. Multiple linear regression analysis revealed that anxiety and simple coping were the main influencing factors of disease uncertainty among parents of children with SWS (P < 0.05). CONCLUSIONS: Parents of children with SWS exhibit a high level of disease uncertainty. Medical staff should pay attention to the source of parents' disease uncertainty and provide targeted interventions, which are of great importance in reducing parents' disease uncertainty.

Combined Trabeculotomy-Non-Penetrating Deep Sclerectomy for Glaucoma in Sturge-Weber Syndrome.

INTRODUCTION: The aim of the study was to evaluate the efficacy and safety of combined trabeculotomy-non-penetrating deep sclerectomy (CTNS) in the treatment of Sturge-Weber syndrome (SWS) secondary glaucoma. METHODS: This retrospective study reviewed cases that underwent CTNS as initial surgery for SWS secondary glaucoma at our Ophthalmology Department center from April 2019 to August 2020. Surgical success was defined as an intraocular pressure (IOP) ≤ 21 mm Hg with (qualified success) or without (complete success) the use of anti-glaucoma medications. IOP >21 mm Hg or <5 mm Hg despite 3 or more applications of anti-glaucoma medications on 2 consecutive follow-up visits or at the last follow-up, performance of additional glaucoma (IOP-lowering) surgery, or with vision-threatening complications were classified as failure. RESULTS: A total of 22 eyes of 21 patients were included. Twenty-one eyes were of early-onset type and 1 eye was of adulthood onset. For Kaplan-Meier survival analysis, the overall success rates at 1st and 2nd years were 95.2% and 84.9%, while the complete success rates at 1st and 2nd years were 42.9% and 36.7%. At the last follow-up (22.3 ± 4.0 months, range: 11.2∼31.2), overall success was achieved in 19 (85.7%) eyes and complete success in 12 (52.4%) eyes. Postoperative complications included transient hyphema (11/22, 50.0%) and transient Ⅰ degree shallow anterior chamber (1/22, 4.5%), and retinal detachment (1/22, 4.5%). No other severe com plications were detected during the follow-up. CONCLUSION: CTNS significantly reduces IOP in SWS secondary glaucoma patients who have serious episcleral vascular malformation. CTNS in SWS secondary glaucoma patients is safe and effective for short and medium periods. A randomized controlled study comparing the long-term prognosis of SWS early-onset and late-onset glaucoma underwent CTNS is worth conducting.

Interaction and Metabolic Function of Microbiota during the Washed Processing of Coffea arabica.

Coffee fermentation is crucial for flavor and aroma, as microorganisms degrade mucilage and produce metabolites. This study aimed to provide a basis for understanding the impact of microorganisms on Coffea arabica from Yunnan, China, during washed processing. The microbial community structure and differentially changed metabolites (DCMs) of C. arabica beans during washed processing were analyzed. The results indicated that the top five predominant microorganisms at the genera level were Achromobacter, Tatumella, Weissella, Streptococcus, and Trichocoleus for bacteria and Cystofilobasidium, Hanseniaspora, Lachancea, Wickerhamomyces, and Aspergillus for fungi. Meanwhile, the relative content of 115 DCMs in 36 h samples decreased significantly, compared to non-fermentation coffee samples (VIP > 1, p < 0.05, FC < 0.65), and the relative content of 28 DCMs increased significantly (VIP > 1, p < 0.05, FC > 1.5). Furthermore, 17 DCMs showed a strong positive correlation with microorganisms, and 5 DCMs had a strong negative correlation (p < 0.05, |r| > 0.6). Therefore, the interaction and metabolic function of microbiota play a key role in the formation of coffee flavor, and these results help in clarifying the fermentation mechanisms of C. arabica and in controlling and improving the quality of coffee flavor.

Experimental demonstration of twin-single-sideband signal detection system based on a single photodetector and without optical bandpass filter.

A twin-single-sideband (twin-SSB) signal single-photodiode (PD) detection system without optical bandpass filter is experimentally demonstrated for the first time. After direct detection by a single-ended PD at the receiver side, we can directly separate the optical left sideband (LSB) and right sideband (RSB) using a simple one-path digital signal processing algorithm without separating the two sideband signals using an optical bandpass filter (OBPF), thus achieving lower complexity and low cost while doubling the spectral efficiency. Using our proposed twin-SSB scheme, we demonstrate 1-, 2-, and 4-Gbaud LSB geometric shaping 4-quadrature amplitude modulation and RSB quadrature phase shift keying signal transmission over 10 km of single-mode fiber (SMF). Our experimental results demonstrate that the bit-error rate (BER) of the 4-Gbaud LSB geometric shaping 4-quadrature amplitude modulation (GS-4QAM) and RSB quadrature phase shift keying (QPSK) transmission system is below the 7% hard decision forward error correction threshold.

Various bond interactions between NO and anionic gold clusters: a theoretical calculation.

We studied the electronic and geometrical structures of AunNO- (n = 1-20) using the B3LYP method with relatively large basis sets to understand the size-dependent reactivities of Aun- with NO in recent experiments. In most cases, the Aun- in a AunNO- maintains its original geometries, and NO bonds with one gold atom in the N-atop pattern. The theoretical adsorption energy of NO in an even-sized AunNO- is generally larger than those in its odd-sized neighbors, which is consistent with the observed even-odd oscillation in experiments. Various bond interactions are identified between Aun- and NO according to analyses on the NO bond lengths, NO stretching frequencies, charge transfer extents, and densities of states of AunNO-. For the odd-sized AunNO- in their doublet states, the bonds between Aun- and NO can be described as weak dative bonds in the small size range, or even weaker electrostatic interactions for the large ones. For the even-sized AunNO- in their triplet states (with the exception of Au10NO- and Au16NO-), the electron transfer from Aun- to NO forms a triplet NO- and a neutral Aun, which bind together mainly through electrostatic interactions. The lowest-lying structures of Au10NO- and Au16NO- are in their singlets, and the bonds between NO and their gold parts can be described as polar covalent bonds. The stabilities of these two exceptional complexes are enhanced by the closed electron shells formed on their gold parts.

Adsorption and Activation of O2 on Small Gold Oxide Clusters: the Reactivity Dominated by Site-Specific Factors.

We experimentally explored adsorption and activation of O2 on small anionic clusters AuxOy- containing one to five gold atoms and between one and three oxygen atoms using an instrument including a magnetron sputtering cluster source, a micro flow reactor running at low temperature, and a time-of-flight mass spectrometer. Some species, including AuO-, one isomer of Au2O2-, Au3O-, one isomer of Au3O3-, and Au5O2-, can adsorb an O2 molecule. We theoretically explored the structures of these active species and the inert ones appearing in the experiment by combining a structure search strategy based on the genetic algorithm and the density functional theory (DFT) calculations. Impressively, all active species observed in the experiment have a -O-Au site, in which the gold atom is a dangling or a vertex atom. Each -O-Au site can strongly adsorb one O2 with its Au atom to form a straight-line structure -O-Au-O-, and the adsorbed O2 is significantly activated by accepting one electron with one of its π2p* orbitals. With no exception, all oxygen sites and the -O-Au-Au sites in AuxOy- are inert. Analyses on the density of states (DOS) of representative species well interpret the physical origins of the activity of -O-Au and the inertness of -O-Au-Au. The observations that site-specific factors dominate the reactivity of gold oxide clusters with O2 are in contrast to what happens in the reactions of Aun- with O2, where clusters' reactivity is completely determined by their global spins and electron detachment energies. The new conclusions in this work offer a reference to understand the crucial O2 activation processes in gold-based catalysts, since various gold oxide structures are commonly observed in these systems.