Activation and Transformation of Methane on Boron-Doped Cobalt Oxide Cluster Cations CoBO2.

The cleavage of inert C-H bonds in methane at room temperature and the subsequent conversion into value-added products are quite challenging. Herein, the reactivity of boron-doped cobalt oxide cluster cations CoBO2+ toward methane under thermal collision conditions was studied by mass spectrometry experiments and quantum-chemical calculations. In this reaction, one H atom and the CH3 unit of methane were transformed separately to generate the product metaboric acid (HBO2) and one CoCH3+ ion, respectively. Theoretical calculations strongly suggest that a catalytic cycle can be completed by the recovery of CoBO2+ through the reaction of CoCH3+ with sodium perborate (NaBO3), and this reaction generates sodium methoxide (CH3ONa) as the other value-added product. This study shows that boron-doped cobalt oxide species are highly reactive to facilitate thermal methane transformation and may open a way to develop more effective approaches for methane (CH4) activation and conversion under mild conditions.

Two Carbon Dioxide Molecules Consecutively Reduced by Metal-Free B2O2- Anions.

Compared with transition metals, nonmetallic elements have always been considered to have low reactivity toward carbon dioxide. However, in recent years, main-group compounds such as boron-based species have gradually attracted increasing attention due to their prospective applications in different kinds of reactions. Herein, we report that metal-free anions B2O2- can promote two CO2 reductions, producing the oxygen-rich product B2O4-. In most of the reported CO2 reduction reactions mediated by transition-metal-containing clusters, transition metals usually provide electrons for the activation of CO2; one oxygen atom in CO2 is transferred to metal atoms, and CO is released from the metal atoms. In sharp contrast, B atoms are electron donors in the current systems and the formed CO is liberated directly from the activated CO2 unit. The synthesis of novel-metal-free gas-phase clusters and investigation of their reactivity toward carbon dioxide as well as reaction mechanisms can provide a fundamental basis in practice for the rational design of active sites on metal-free catalysts.

Plasma-Assisted Coupling Reactions of Dinitrogen and Carbon Dioxide Mediated by Monometallic YB1-4 - ⋠Anions: Carbon-Nitrogen Bond Formation.

Transition-metal catalyzed coupling to form C-N bonds is significant in chemical science. However, the inert nature of N2 and CO2 renders their coupling quite challenging. Herein, we report the activation of dinitrogen in the mild plasma atmosphere by the gas-phase monometallic YB1-4 - anions and further coupling of CO2 to form C-N bonds by using mass spectrometry and theoretical calculation. The observed product anions are NCNBO- and N(BO)2 - , accompanied by the formation of neutral products YO and YB0-2 NC, respectively. We can tune the reactivity and the type of products by manipulating the number of B atoms. The B atoms in YB1-4 N2 - act as electron donors in CO2 reduction reactions, and the carbon atom originating from CO2 serves as an electron reservoir. This is the first example of gas-phase monometallic anions, which are capable to realize the functionalization of N2 with CO2 through C-N bond formation and N-N and C-O bond cleavage.

Lithium-Assisted Dinitrogen Reduction Mediated by Nb2LiNO1-4- Cluster Anions: Electron Donors or Structural Units.

Alkali atoms are usually used as promoters to significantly increase the catalytic activity of transition-metal catalysts in a wide range of reactions such as dinitrogen conversion reactions. However, the role of alkali metal atoms remains controversial. Herein, a series of quaternary cluster anions containing lithium atoms Nb2LiNO1-4- have been synthesized and reacted with N2 at room temperature. The detailed experimental and theoretical investigations indicate that Nb2LiNO- is capable to cleave the N≡N bond and the Li atoms in Nb2LiNO1,2- act as electron donors in the N2 reduction reaction. With the increase in the number of oxygen atoms, the reactivity toward N2 is reduced from adsorption via a side-on end-on mode in Nb2LiNO2- to the inertness of Nb2LiNO4-. In Nb2LiNO3,4- anions, the Li atoms are bonded with oxygen atoms, acting as structural units to stabilize structures. Therefore, the roles of alkali atoms are able to change with different chemical environments of active sites. For the first time, we reveal how the number of ligands (oxygen atoms herein) can be used to finely regulate the reactivity toward N2.

Metabolic profiling of nanosilver toxicity in the gills of common carp.

Studies have shown silver nanoparticles (AgNPs) exposure can result in a series of toxic effects in fish gills. However, it is still unclear how AgNPs affect metabolite expression and their related molecular metabolic pathways in fish gills. In this study, we employed untargeted metabolomics to study the effects of AgNPs and silver supernatant ions on fish gill metabolites. The results showed that AgNPs can induce significant changes in 96 differentially expressed metabolites, which mainly affect amino acid metabolism and energy metabolism in fish gills. Among these metabolites, AgNPs specifically induce significant changes in 72 differentially expressed metabolites, including L-histidine, L-isoleucine, L-phenylalanine, and citric acid. These metabolites were significantly enriched in the pathways of aminoacyl-tRNA biosynthesis, ABC transporters, and the citrate cycle. In contrast, Ag+ supernatant exposure can specifically induce significant changes in 14 differentially expressed metabolites that mainly interfere with sphingolipid metabolism in fish gills. These specifically regulated fish gill metabolites include sphinganine, sphingosine, and phytosphingosine, which were significantly enriched in the sphingolipid metabolism pathway. Our results clearly reveal the effects and potential toxicity mechanisms of AgNPs on fish gill metabolites. Furthermore, our study further determined the unique functions of released silver ions in AgNPs toxicity in fish gills.

Electrical exposure analysis of galvanic-coupled intra-body communication based on the empirical arm models.

BACKGROUND: Intra-body communication (IBC) is one of the highlights in studies of body area networks. The existing IBC studies mainly focus on human channel characteristics of the physical layer, transceiver design for the application, and the protocol design for the networks. However, there are few safety analysis studies of the IBC electrical signals, especially for the galvanic-coupled type. Besides, the human channel model used in most of the studies is just a multi-layer homocentric cylinder model, which cannot accurately approximate the real human tissue layer. METHODS: In this paper, the empirical arm models were established based on the geometrical information of six subjects. The thickness of each tissue layer and the anisotropy of muscle were also taken into account. Considering the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines, the restrictions taken as the evaluation criteria were the electric field intensity lower than 1.35 × 104 f V/m and the specific absorption rate (SAR) lower than 4 W/kg. The physiological electrode LT-1 was adopted in experiments whose size was 4 × 4 cm and the distance between each center of adjoining electrodes was 6 cm. The electric field intensity and localized SAR were all computed by the finite element method (FEM). The electric field intensity was set as average value of all tissues, while SAR was averaged over 10 g contiguous tissue. The computed data were compared with the 2010 ICNIRP guidelines restrictions in order to address the exposure restrictions of galvanic-coupled IBC electrical signals injected into the body with different amplitudes and frequencies. RESULTS: The input alternating signal was 1 mA current or 1 V voltage with the frequency range from 10 kHz to 1 MHz. When the subject was stimulated by a 1 mA alternating current, the average electric field intensity of all subjects exceeded restrictions when the frequency was lower than 20 kHz. The maximum difference among six subjects was 1.06 V/m at 10 kHz, and the minimum difference was 0.025 V/m at 400 kHz. While the excitation signal was a 1 V alternating voltage, the electric field intensity fell within the exposure restrictions gradually as the frequency increased beyond 50 kHz. The maximum difference among the six subjects was 2.55 V/m at 20 kHz, and the minimum difference was 0.54 V/m at 1 MHz. In addition, differences between the maximum and the minimum values at each frequency also decreased gradually with the frequency increased in both situations of alternating current and voltage. When SAR was introduced as the criteria, none of the subjects exceeded the restrictions with current injected. However, subjects 2, 4, and 6 did not satisfy the restrictions with voltage applied when the signal amplitude was ≥ 3, 6, and 10 V, respectively. The SAR differences for subjects with different frequencies were 0.062-1.3 W/kg of current input, and 0.648-6.096 W/kg of voltage input. CONCLUSION: Based on the empirical arm models established in this paper, we came to conclusion that the frequency of 100-300 kHz which belong to LF (30-300 kHz) according to the ICNIRP guidelines can be considered as the frequency restrictions of the galvanic-coupled IBC signal. This provided more choices for both intensities of current and voltage signals as well. On the other hand, it also makes great convenience for the design of transceiver hardware and artificial intelligence application. With the frequency restrictions settled, the intensity restrictions that the current signal of 1-10 mA and the voltage signal of 1-2 V were accessible. Particularly, in practical application we recommended the use of the current signals for its broad application and lower impact on the human tissue. In addition, it is noteworthy that the coupling structure design of the electrode interface should attract attention.

[Application of ultrasonic cardiac output monitor in evaluation of cardiac function in children with severe pneumonia].

OBJECTIVE: To study the clinical application of ultrasonic cardiac output monitor (USCOM) in evaluation of cardiac function in children with severe pneumonia. METHODS: Twenty-nine children with severe pneumonia were enrolled in the observation group and forty-three children with common pneumonia were enrolled in the control group. The USCOM was used to measure the cardiac function indices in the two groups. The results were compared between the two groups. The changes in cardiac function indices after treatment were evaluated in the observation group. ESULTS: The observation group had a significantly higher heart rate and significantly lower cardiac output, systolic volume, and aortic peak velocity than the control group (P<0.05). There were no significant differences in cardiac index or systemic vascular resistance between the two groups (P>0.05). In the observation group, the heart rate, cardiac output, systolic volume, aortic peak velocity, cardiac index, and systemic vascular resistance were significantly improved after treatment (P<0.05). CONCLUSIONS: The USCOM is a fast, convenient, and accurate approach for dynamic measurement of cardiac function and overall circulation state in children with severe pneumonia. The USCOM can provide a basis for diagnosis, treatment, and evaluation of the disease, which is quite useful in clinical practice.

Minicircle DNA vectors achieve sustained expression reflected by active chromatin and transcriptional level.

Current efforts in nonviral gene therapy are plagued by a pervasive difficulty in sustaining therapeutic levels of delivered transgenes. Minicircles (plasmid derivatives with the same expression cassette but lacking a bacterial backbone) show sustained expression and hold promise for therapeutic use where persistent transgene expression is required. To characterize the widely-observed silencing process affecting expression of foreign DNA in mammals, we used a system in which mouse liver presented with either plasmid or minicircle consistently silences plasmid but not minicircle expression. We found that preferential silencing of plasmid DNA occurs at a nuclear stage that precedes transport of mRNA to the cytoplasm, evident from a consistent >25-fold minicircle/plasmid transcript difference observed in both nuclear and total RNA. Among possible mechanisms of nuclear silencing, our data favor chromatin-linked transcriptional blockage rather than targeted degradation, aberrant processing, or compromised mRNA transport. In particular, we observe dramatic enrichment of H3K27 trimethylation on plasmid sequences. Also, it appears that Pol II can engage the modified plasmid chromatin, potentially in a manner that is not productive in the synthesis of high levels of new transcript. We outline a scenario in which sustained differences at the chromatin level cooperate to determine the activity of foreign DNA.

Minicircle DNA is superior to plasmid DNA in eliciting antigen-specific CD8+ T-cell responses.

Clinical trials reveal that plasmid DNA (pDNA)-based gene delivery must be improved to realize its potential to treat human disease. Current pDNA platforms suffer from brief transgene expression, primarily due to the spread of transcriptionally repressive chromatin initially deposited on plasmid bacterial backbone sequences. Minicircle (MC) DNA lacks plasmid backbone sequences and correspondingly confers higher levels of sustained transgene expression upon delivery, accounting for its success in preclinical gene therapy models. In this study, we show for the first time that MC DNA also functions as a vaccine platform. We used a luciferase reporter transgene to demonstrate that intradermal delivery of MC DNA, relative to pDNA, resulted in significantly higher and persistent levels of luciferase expression in mouse skin. Next, we immunized mice intradermally with DNA encoding a peptide that, when presented by the appropriate major histocompatibility complex class I molecule, was recognized by endogenous CD8(+) T cells. Finally, immunization with peptide-encoding MC DNA, but not the corresponding full-length (FL) pDNA, conferred significant protection in mice challenged with Listeria monocytogenes expressing the model peptide. Together, our results suggest intradermal delivery of MC DNA may prove more efficacious for prophylaxis than traditional pDNA vaccines.

Effect of electroacupuncture combined with rehabilitation techniques on shoulder function in patients with rotator cuff injuries.

BACKGROUND: The rotator cuff is located below the acromion and deltoid muscles and comprises multiple tendons that wrap around the humeral head, maintaining shoulder joint stability. AIM: To explore the effect of electroacupuncture combined with rehabilitation techniques on shoulder function in patients with rotator cuff injuries. METHODS: We selected 97 patients with rotator cuff injuries treated in the People's Hospital of Yuhuan from February 2020 to May 2023. Patients were grouped using the envelope method. RESULTS: After treatment, the study group's treatment effective rate was 94.90% (46/49 patients), significantly higher than that in the control group (79.17%, 38/48 cases; P < 0.05). Before treatment, there was no difference in Constant Murley Score (CMS) scores, shoulder mobility, or 36-Item Short Form Health Survey (SF-36) scale scores (P > 0.05). Compared with those before treatment, the CMS scores (including pain, daily living ability, shoulder mobility, and muscle strength), all aspects of shoulder mobility (forward flexion, posterior extension, external rotation, internal rotation), and SF-36 scale scores (including physiological, psychological, emotional, physical, vitality, and health status) were higher in both groups after treatment and significantly higher in the study group (P < 0.05). There was no difference in the occurrence of complications between the two treatment groups (P > 0.05). CONCLUSION: Electroacupuncture combined with rehabilitation techniques has a good treatment effect on patients with rotator cuff injuries, helps accelerate the recovery of shoulder function, improves the quality of life, and is highly safe.