Machine Learning for Experimental Reactivity of a Set of Metal Clusters toward C-H Activation.

Understanding the mechanisms of C-H activation of alkanes is a very important research topic. The reactions of metal clusters with alkanes have been extensively studied to reveal the electronic features governing C-H activation, while the experimental cluster reactivity was qualitatively interpreted case by case in the literature. Herein, we prepared and mass-selected over 100 rhodium-based clusters (RhxVyOz- and RhxCoyOz-) to react with light alkanes, enabling the determination of reaction rate constants spanning six orders of magnitude. A satisfactory model being able to quantitatively describe the rate data in terms of multiple cluster electronic features (average electron occupancy of valence s orbitals, the minimum natural charge on the metal atom, cluster polarizability, and energy gap involved in the agostic interaction) has been constructed through a machine learning approach. This study demonstrates that the general mechanisms governing the very important process of C-H activation by diverse metal centers can be discovered by interpreting experimental data with artificial intelligence.

Activation of Methane by Rhodium Clusters on a Model Support C20H10.

Supported metals represent an important family of catalysts for the transformation of the most stable alkane, methane, under mild conditions. Here, using state-of-the-art mass spectrometry coupled with a newly designed double ion trap reactor that can run at high temperatures, we successfully immobilize a series of Rhn- (n = 4-8) cluster anions on a model support C20H10. Reactivity measurements at room temperature identify a significantly enhanced performance of large-sized Rh7,8C20H10- toward methane activation compared to that of free Rh7,8-. The "support" acting as an "electron sponge" is emphasized as the key factor to improve the reactivity of large-sized clusters, for which the high electron-withdrawing capability of C20H10 dramatically shifts the active Rh atom from the apex position in free Rh7- to the edge position in "supported" Rh7- to enhance CH4 adsorption, while the flexibility of C20H10 to release electrons further promotes subsequent C-H activation. The Rh atoms in direct contact with the support serve as electron-relay stations for electron transfer between C20H10 and the active Rh atom. This work not only establishes a novel approach to prepare and measure the reactivity of "supported" metal clusters in isolated gas phase but provides useful atomic-scale insights for understanding the chemical behavior of carbon (e.g., graphene)-supported metals in heterogeneous catalysis.

Infected wound repair with an ultrasound-enhanced nanozyme hydrogel scaffold.

Chronic diabetic wounds persistently face the threat of evolving into diabetic foot ulcers owing to severe hypoxia, high levels of reactive oxygen species (ROS), and a complex inflammatory microenvironment. To concurrently surmount these obstacles, we developed an all-round therapeutic strategy based on nanozymes that simultaneously scavenge ROS, generate O2 and regulate the immune system. First, we designed a dynamic covalent bond hybrid of a metal-organic coordination polymer as a synthesis template, obtaining high-density platinum nanoparticle assemblies (PNAs). This compact assembly of platinum nanoparticles not only effectively simulates antioxidant enzymes (CAT, POD) but also, under ultrasound (US), enhances electron polarization through the surface plasmon resonance effect, endowing it with the ability to induce GSH generation by effectively replicating the enzyme function of glutathione reductase (GR). PNAs, by mimicking the activity of CAT and POD, effectively catalyze hydrogen peroxide, alleviate hypoxia, and effectively generate GSH under ultrasound, further enhancing ROS scavenging. Notably, PNAs can regulate macrophage responses in the inflammatory microenvironment, circumventing the use of any additives. It was confirmed that PNAs can enhance cell proliferation and migration, promote neoangiogenesis IN VITRO, and accelerate the healing of infected diabetic wounds IN VIVO. We believe that an all-round therapeutic method based on PNA nanozymes could be a promising strategy for sustained diabetic wound healing.

Pyrolysis of mass-selected (V2O5)NO- (N = 1-6) clusters in a high-temperature linear ion trap reactor.

A high-temperature linear ion trap that can stably run up to 873 K was newly designed and installed into a homemade reflectron time-of-flight mass spectrometer coupled with a laser ablation cluster source and a quadrupole mass filter. The instrument was used to study the pyrolysis behavior of mass-selected (V2O5)NO- (N = 1-6) cluster anions and the dissociation channels were clarified with atomistic precision. Similar to the dissociation behavior of the heated metal oxide cluster cations reported in literature, the desorption of either atomic oxygen atom or molecular O2 prevailed for the (V2O5)NO- clusters with N = 2-5 at 873 K. However, novel dissociation channels involving fragmentation of (V2O5)NO- to small-sized VxOy - anions concurrent with the release of neutral vanadium oxide species were identified for the clusters with N = 3-6. Significant variations in branching ratios for different dissociation channels were observed as a function of cluster size. Kinetic studies indicated that the dissociation rates of (V2O5)NO- monotonically increased with the increase in cluster size. The internal energies carried by the (V2O5)NO- clusters at 873 K as well as the energetics data for dissociation channels have been theoretically calculated to rationalize the experimental observations. The decomposition behavior of vanadium oxide clusters from this study can provide new insights into the pyrolysis mechanism of metal oxide nanoparticles that are widely used in high temperature catalysis.

Shoulder transcutaneous electric nerve stimulation decreases heart rate via potentiating vagal tone.

By enhancing vagal activity, auricle transcutaneous electric nerve stimulation (TENS) is developed as a non-invasive therapy for heart failure. Nevertheless, though shoulder TENS used for treating adhesive capsulitis could affect vagal tone, its potential impact on heart functions remains unclear. In this study, electrocardiogram (ECG) and heart rate (HR) of subjects in response to sham, right-sided, or left-sided shoulder TENS (TENS-S, TENS-R, and TENS-L, respectively; 5 min) were recorded and analyzed. During the stimulation period, TENS-R constantly and TENS-L transiently decreased the HR of subjects; both TENS-R and TENS-L increased powers of the low- and high-frequency spectra. While TENS-R exhibiting no effect, TENS-L increased the ratio of low/high-frequency power spectrum indicating TENS-R decreased the HR through potentiating cardiac vagal tone. Collectively, these results suggest TENS could be an early and non-invasive therapy for heart failure patients before considering implant devices or devices are not feasible; moreover, therapists/physicians need to carefully monitor the potential adverse events during treatment for patient safety.Trial registration: The study protocol was registered in ClinicalTrials.gov (NCT03982472; 11/06/2019).

Rhodium chemistry: A gas phase cluster study.

Due to the extraordinary catalytic activity in redox reactions, the noble metal, rhodium, has substantial industrial and laboratory applications in the production of value-added chemicals, synthesis of biomedicine, removal of automotive exhaust gas, and so on. The main drawback of rhodium catalysts is its high-cost, so it is of great importance to maximize the atomic efficiency of the precious metal by recognizing the structure-activity relationship of catalytically active sites and clarifying the root cause of the exceptional performance. This Perspective concerns the significant progress on the fundamental understanding of rhodium chemistry at a strictly molecular level by the joint experimental and computational study of the reactivity of isolated Rh-based gas phase clusters that can serve as ideal models for the active sites of condensed-phase catalysts. The substrates cover the important organic and inorganic molecules including CH4, CO, NO, N2, and H2. The electronic origin for the reactivity evolution of bare Rhx q clusters as a function of size is revealed. The doping effect and support effect as well as the synergistic effect among heteroatoms on the reactivity and product selectivity of Rh-containing species are discussed. The ingenious employment of diverse experimental techniques to assist the Rh1- and Rh2-doped clusters in catalyzing the challenging endothermic reactions is also emphasized. It turns out that the chemical behavior of Rh identified from the gas phase cluster study parallels the performance of condensed-phase rhodium catalysts. The mechanistic aspects derived from Rh-based cluster systems may provide new clues for the design of better performing rhodium catalysts including the single Rh atom catalysts.

Research advances in the clinical and basic research on Fuzheng Huayu prescription in treatment of chronic liver diseases / 临床肝胆病杂志

Fuzheng Huayu prescription is developed by Shanghai University of Traditional Chinese Medicine and has the functions of promoting blood circulation, removing blood stasis, nourishing essence, and tonifying the liver, and it is an effective empirical prescription for the treatment of chronic liver diseases including chronic viral hepatitis, nonalcoholic fatty liver disease, liver fibrosis, liver cirrhosis, and liver cancer. This prescription has been used in clinical practice for many years and has a marked clinical effect in alleviating clinical symptoms and improving liver fibrosis and complications. In recent years, many scholars have conducted in-depth studies on the clinical effect and mechanism of action of Fuzheng Huayu prescription in the treatment of chronic liver diseases and achieved satisfactory results. This article summarizes related research findings in order to provide a reference for subsequent studies.

Compact Conjugated Polymer Dots with Covalently Incorporated Metalloporphyrins for Hypoxia Bioimaging.

Hypoxia is closely related to multiple diseases, especially in tumors, which increases the aggressiveness and drug resistance of cancer cells. Precise hypoxia imaging is of great significance for cancer diagnosis and the evaluation of therapeutic effects. A kind of hydrophobic polymer (i.e., PFPtTFPP) as an imaging probe for hypoxia with fluorene as an energy donor and an oxygen-sensitive PtII porphyrin as an energy acceptor was developed. Compact polymer dots (Pdots) with a small size were prepared by nanoprecipitation. The PFPtTFPP Pdots showed excellent hypoxia sensing in solution with high sensitivity and full reversibility. The emission intensity, quantum yields, lifetime, and single-particle brightness significantly increased under hypoxia conditions. Remarkably, hypoxia imaging in vitro and in vivo was realized, and a clear increase in brightness was observed under hypoxia conditions and in the tumor area. Excellent hypoxia imaging ability is beneficial to potential applications in cancer diagnosis.

Water assisted biomimetic synergistic process and its application in water-jet rewritable paper.

The colour of water-jet rewritable paper (WJRP) is difficult to be expanded via single hydrochromic molecule, especially black. Here, inspired by the amazing phenomenon of bound-water in cells enabling various biological transformations via facilitating synergistic inter-/intra-molecular proton transfer, we present a simple strategy toward WJRP based on binary systems containing less-sensitive acidochromic dyes and mild proton donors (or developers). With such a binary system containing commercial black dye as the colouring agent, benzyl 4-hydroxybenzoate as the developer, and biomimetic bound-water as proton-transferring medium, we successfully achieve the long-awaited black WJRP. Printed images on such WJRP have excellent performances and long retaining time (>1 month). In addition, the robustness, durability and reversibility of WJRP could be increased distinctly by using polyethylene terephthalate as substrate. This strategy significantly expands hydrochromic colours to entire visible range in an eco-friendly way, which opens an avenue of smart materials for practical needs and industrialization.

Photooxidation of oxazolidine molecular switches: uncovering an intramolecular ionization facilitated cyclization process.

Photooxidation of oxazoline (OXA) molecular switches through media-induced intramolecular ionization is reported. The formation of the photooxidation product occurs by attack of the flexible donor group (-CH2CH2OH) to the adjacent C[double bond, length as m-dash]C with 1O2 as the oxidant. The novel seven-membered ring sub-structure of the photooxidation product was inferred by HRMS, IR and 1H NMR spectroscopy. Additionally, acid released from solvent photolysis was found to affect the product formation and efficiency of the photooxidation.

Endowing Hydrochromism to Fluorans via Bioinspired Alteration of Molecular Structures and Microenvironments and Expanding Their Potential for Rewritable Paper.

Interest and effort toward new materials for rewritable paper have increased dramatically because of the exciting advantages for sustainable development and better nature life cycle. Inspired by how nature works within living systems, herein, we have used fluorans, as a concept verification, to endow original acidochromic, basochromic or photochromic molecules with broader properties, such as switchable with solvent, water, heat, electricity, stress, other force, etc., via simplified methods (i.e., via variation of submolecular structure or microenvironments). The hydrochromic visual change and reversible behavior of selected molecules have been explored, and the primary mechanism at the atomic or subatomic level has been hypothesized. In addition, several newly demonstrated hydrochromic fluorans have been utilized for water-jet rewritable paper (WJRP), which exhibit great photostability, high hydrochromic contrast, and fast responsive rate and which can be reused at least 30 times without significant variation. The water-jet prints have good resolution and various colors and can keep legibility after a few months or years. This improved performance is a major step toward practical applications of WJRP.

Effect of Xiaoying Decoction on Changes of Regulatory T Cells and Th17 Cells in Experimental Autoimmune Thyroiditis Rats / 医药导报

Objective To explore the mechanism of Xiaoying decoction on experimental autoimmune thyroiditis (EAT) rats in view of regulatory T cells and Th17 cells.Methods SD rats were divided into five groups,normal control group,model control group,tripterygium glycoside group,Xiaoying decoction low and high dose groups.Except for normal control group,the other groups were established the model of EAT.Rats in the Xiaoying decoction low,and high dose groups were given Xiaoying decoction of 17.24 and 68.95 g·kg-1;rats in the tripterygium glycoside group were given tripterygium glycoside 6.25 mg·kg-1.The serum free triiodothyronine(FT3),free thyrocyte(FT4) and thyroglobulin antibody were detected by RIA method.Thyrocyte morphology was observed under optical microscope.The expression levels of Foxp3 mRNA and IL-17 mRNA were detected by real-time PCR.The changes of Treg cells and Th17 cells were analyzed by flow cytometry.Results Compared with the normal control group,FT3,FT4 and TgAb were increased in the model control group (P ＜0.01,P ＜0.01,P ＜0.05).Compared with the model control group,FT3,FT4 and TgAb were decreased in tripterygium glycoside group and Xiaoying decoction high dose group (P ＜ 0.05).The infiltration score in the normal control group,model control group,tripterygium glycoside group,Xiaoying decoction low and high dose groups were 0,4,4,3.5,2.Compared with model control group,the infiltration was improved (P ＜0.01).Foxp3 mRNA expression was decreased while IL-17 mRNA increased in the model control group as compared with the normal control group(P ＜ 0.01).In contrast,the expression of Foxp3 mRNA was increased and IL-17 mRNA expression was decreased in Xiaoying decoction low and high dose groups,tripterygium glycoside group as compared with the model control group (P ＜0.05).Compared with the normal control group,rats in the model control group had fewer Treg cells and more Th17 cells (P ＜0.01).Compared with the model control group,the percentage of Treg cells was elevated and Th17 cells was reduced in tripterygium glycoside group and Xiaoying decoction high dose groups (P ＜ 0.01).Conclusion The therapeutic mechanism of Xiaoying decoction on EAT rats may be related to changing the percentage of regulatory T cells and Th17 cells with up-regulating the expression of Foxp3 mRNA and down-regulating the expression of IL17mRNA.

Ideas Exploration and Analysis on the Prescription Comment of TCM Injections / 中国药房

OBJECTIVE:To explore the ideas for the prescription comment of TCM injections,and provide reference for clini-cal rational use. METHODS:Totally 9 457 prescriptions in PIVAS and 400 hospitalized medical records in our hospital in 2015 were collected. The prescriptions and hospitalized medical records which contained TCM injections were retrospectively commented in aspects of indications,usage and dosage,drug combination,solvent selection and repeat medication,and analysis of typical case. RESULTS:In 2015,there were 2 544 prescriptions(26.90%)in PIVAS and 195 medical records(48.75%)that used TCM injections;the irrational use was mainly inappropriate solvent selection(50.70%),inappropriate usage and dosage(27.00%),inap-propriate indications (10.33%),inappropriate combination therapy (7.51%) and repeat medication (4.46%). CONCLUSIONS:Prescription of TCM injections should be commented with the medical records and individual analyzed;in terms of unreasonable prescriptions and medical records TCM clinical pharmacists should actively intervene unreasonable prescriptions by the bed.

Hydrochromic molecular switches for water-jet rewritable paper.

The days of rewritable paper are coming, printers of the future will use water-jet paper. Although several kinds of rewritable paper have been reported, practical usage of them is rare. Herein, a new rewritable paper for ink-free printing is proposed and demonstrated successfully by using water as the sole trigger to switch hydrochromic dyes on solid media. Water-jet prints with various colours are achieved with a commercial desktop printer based on these hydrochromic rewritable papers. The prints can be erased and rewritten dozens of times with no significant loss in colour quality. This rewritable paper is promising in that it can serve an eco-friendly information display to meet the increasing global needs for environmental protection.

One-pot synthesis of pillar[n]arenes catalyzed by a minimum amount of TfOH and a solution-phase mechanistic study.

A practical and effective trifluoromethanesulfonic acid (TfOH)-catalyzed cyclooligomerization strategy was developed for the synthesis of functionalized pillar[n]arenes and copillar[5]arenes from 1,4-dialkoxybenzenes with paraformaldehyde under mild reaction conditions, and the reaction mechanism of solution-phase catalytic synthesis of pillararenes was investigated by room-temperature X-band ESR spectroscopy, mass spectroscopy, NMR and control experiments, suggesting a free radical process initially and a Friedel-Crafts alkylation process during the consequent coupling and ring-closure stage.