High-Performance Graphene Flexible Sensors for Pulse Monitoring and Human-Machine Interaction.

Flexible sensors are of great interest due to their potential applications in human physiological signal monitoring, wearable devices, and healthcare. However, sensor devices employed for cardiovascular testing are normally bulky and expensive, which hamper wearability and point-of-care use. Herein, we report a simple method for preparing multifunctional flexible sensors using hydrazine hydrate (N2H4·H2O) as the reducing agent, graphene as the active material, and polyethylene (PE) tape as the encapsulation material. The flexible sensor produced with this method has a low detection limit of 100 mg, a fast response and recovery time of 40 and 20 ms, and shows no performance degradation even after up to 30,000 motion cycles. The sensors we have developed are capable of monitoring the pulse with relative accuracy, which presents an opportunity to replace bulky devices and normalize cardiovascular testing in the future. In order to further broaden the application field, the sensor is installed as a sensor array to recognize objects of different weights and shapes, showing that the sensor has excellent application potential in wearable artificial intelligence.

Highly Selective Pb(II) Adsorption by DTPA-Functionalized Graphene Oxide/Carboxymethyl Cellulose Aerogel.

Graphene oxide (GO) exhibits a strong adsorption capacity for the removal of heavy metal ions from liquids, making it a topic of increasing interest among researchers. However, a significant challenge persists in the preparation of graphene oxide-based adsorbents that possess both high structural stability and excellent adsorption capacity. In this paper, a green and environmentally friendly ternary composite aerogel based on graphene was successfully synthesized. The adsorption capacity of graphene oxide was enhanced through diethylenetriaminepentaacetic acid modification, while the incorporation of composite carboxymethyl cellulose improved the structural stability of the composite aerogel in liquid. The composite aerogel demonstrates robust interactions between its components and features a multiscale porous structure. Adsorption tests conducted with Pb(II) revealed that the GO/DTPA/CMC (GDC) composite aerogel exhibits a favorable adsorption capacity. The study of adsorption kinetics and isotherms indicated that the adsorption process follows the quasi-secondary adsorption model and Freundlich adsorption model, suggesting a chemical multilayer adsorption mechanism, and the maximum adsorption capacity for Pb(II) ions was 521.917 mg/g based on the quasi-quadratic kinetic model fitting. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analyses, performed before and after adsorption, confirmed that the adsorption of Pb(II) primarily occurs through chelation, complexation, proton exchange, and electrostatic interactions between ions and active sites such as hydroxyl and carboxyl groups. This study presents an innovative strategy for simultaneously enhancing the adsorption properties of graphene oxide-based composite aerogels and ensuring solution stability.

Divergent Regioselective Csp2-H Difluoromethylation of Aromatic Amines Enabled by Nickel Catalysis.

Herein, the first catalytic protocol for nickel-catalyzed ortho or para position difluoromethylation of various aromatic amines has been developed with the assistance of a bidentate phosphine ligand, offering an invaluable synthesis means to construct extensive p-difluoromethylated products and difluorooxindole derivatives with significant functional fragments. Furthermore, the gram-scale reaction, broad substrate scope, excellent functional-group compatibility, late-stage difluoromethylation of pesticides, and even formal synthesis of HDAC6 inhibitors further demonstrate the usefulness of this method.

C(sp3)-H Monoarylation of Methanol Enabled by a Bidentate Auxiliary.

With the assistance of a practical directing group (COAQ), the first catalytic protocol for the palladium-catalyzed C(sp3)-H monoarylation of methanol has been developed, offering an invaluable synthesis means to establish extensive derivatives of crucial arylmethanol functional fragments. Furthermore, the gram-scale reaction, broad substrate scope, excellent functional group compatibility, and even the practical synthesis of medicines further demonstrate the usefulness of this strategy.

Nanocomposite Based on Organic Framework-Loading Transition-Metal Co Ion and Cationic Pillar[6]arene and Its Application for Electrochemical Sensing of l-Ascorbic Acid.

In this study, we constructed a highly sensitive and selective electrochemical sensing strategy for l-ascorbic acid (AA) based on a covalent organic framework (COF)-loading non-noble transition metal Co ion and macrocyclic cationic pillar[6]arene (CP6) nanocomposite (CP6-COF-Co). The COF plays a crucial role in anchoring the Co ion according to its crystalline porous and multiple coordination sites and has an outstanding performance for building an electrochemical sensing platform based on a unique two-dimensional structure. Accordingly, the transition-metal Co ion can be successfully anchored on the framework of COF and shows strong catalytic activity for the determination of AA. Moreover, introduction of host-guest recognition based on CP6 and AA can bring new properties for enhancing selectivity, sensitivity, and practical application in real environment. Host-guest interactions between CP6 and AA were evaluated by the 1H NMR spectrum. When compared with other literatures, our method displayed a lower determination limit and broader linear range. To the best of our knowledge, this is the first study carried out for the non-noble transition-metal Co ion, COF, and pillar[6]arene hybrid material in sensing field, which has a potential value in sensing, catalysis, and preparation of advanced multifunction materials.

Cobalt-Catalyzed C-H Acetoxylation of Phenols with Removable Monodentate Directing Groups: Access to Pyrocatechol Derivatives.

An efficient cobalt-catalyzed C-H acetoxylation of phenols has been developed by using PIDA (phenyliodine diacetate) as a sole acetoxy source to synthesize pyrocatechol derivatives for the first time. The key feature of this method is the use of earth-abundant metal cobalt as the green and inexpensive catalyst for the acetoxylation of C(sp2)-H bonds under neutral reaction conditions. Furthermore, the gram-scale reaction and late-stage functionalization demonstrated the usefulness of this method.

Copper-Catalyzed Coupling of Sulfonamides with Alkylamines: Synthesis of (E)-N-Sulfonylformamidines.

Herein, we describe an efficient copper-catalyzed coupling of sulfonamides with alkylamines to synthesize (E)-N-sulfonylformamidines. The reaction is accomplished under mild conditions without the use of a corrosive acid or base as an additive. It tolerates a broad scope of substrates and generates the products with exclusive (E)-stereoselectivity.

The synthesis of water-soluble phosphate pillar[5]arenes functionalized graphene as a fluorescent probe for sensitive detection of paraquat.

We describe a selective and sensitive fluorescence platform for the detection of paraquat (PQ) based on competitive host-guest recognition between phosphate pillar[5]arenes (PWP5) and probe (Safranine T, ST) with using PWP5 functionalized reduced graphene (PWP5-rGO) as the receptor. PQ is a positive charge molecule that is captured by PWP5 via electrostatic interactions. The host-guest interaction between PWP5 and PQ is studied by 1H NMR. Therefore, a selective and sensitive fluorescence sensing of detection PQ is developed. It has a linear response ranges of 0.01-2.0 and 2.0-50.0 µM and a low detection limit of 0.0035 µM (S/N = 3) for PQ. The sensing platform is also used to test PQ in two water samples with satisfying results. It suggests that this approach has potential applications for the determination of PQ.

Intermolecular Amination of Unactivated C(sp3 )-H Bonds with Cyclic Alkylamines: Formation of C(sp3 )-N Bonds through Copper/Oxygen-Mediated C(sp3 )-H/N-H Activation.

The first example of intermolecular amination of unactivated C(sp3 )-H bonds by cyclic alkylamines mediated by Cu(OAc)2 /O2 is reported. This method avoids the use of benzoyloxyamines as the aminating reagent, which are normally prepared from alkylamines in extra steps. A variety of unnatural ß2, 2 -amino acid analogues are synthesized by this simple and efficient procedure. This approach offers a solution to the previous unmet challenge of C(sp3 )-H/N-H activation for the formation of C(sp3 )-N bonds.

Pd(II) -Catalyzed Intermolecular Amination of Unactivated C(sp(3) )-H Bonds.

Pd(II) -catalyzed intermolecular amination of unactivated C(sp(3) )-H bonds has been successfully developed for the first time. This method provides a new way to achieve the challenging intermolecular amination of unactivated C(sp(3) )-H bonds, producing a variety of unnatural ß(2) -amino carboxylic acid analogues. This C(sp(3) )-H amination protocol is demonstrated with a broad substrate scope, good functional-group tolerance, and chemoselectivity. It is operated without use of phosphine ligand or external oxidant.

Palladium-catalyzed arylation of (di)azinyl aldoxime ethers by aryl iodides: stereoselective synthesis of unsymmetrical (E)-(di)azinylaryl ketoxime ethers.

The first example of direct arylation of (di)azinyl aldoxime ethers by aryl iodides is reported. The reaction produces, in a single step, a variety of geometrically pure unsymmetrical (E)-(di)azinylaryl ketoxime ethers, a class of nitrogenated motifs that have found wide applications in medicinal and organic chemistry but are difficult to access using conventional procedure. The utility of the method is further illustrated in a formal synthesis of the Merck melanin-concentrating hormone 1 receptor antagonist.

Palladium-catalyzed Cs2CO3-promoted arylation of unactivated C(sp(3))-H bonds by (diacetoxyiodo)arenes: shifting the reactivity of (diacetoxyiodo)arenes from acetoxylation to arylation.

PdCl2(CH3CN)2-catalyzed arylation of unactivated C(sp(3))-H bonds using (diacetoxyiodo)arenes as arylation reagents is reported. The reactivity of (diacetoxyiodo)arenes as arylation reagents is enabled in the presence of Cs2CO3 under the reaction conditions. This arylation method is highly efficient and occurs without the use of silver salt. The reaction tolerates a broad substrate scope that was not demonstrated by other silver salt-free C(sp(3))-H bond arylation conditions. The synthetic utility of the method is further illustrated in the synthesis of the psychotropic drug phenibut. A detailed mechanism study has been conducted to understand the reaction pathway.

Arylations of substituted enamides by aryl iodides: regio- and stereoselective synthesis of (Z)-ß-amido-ß-arylacrylates.

Arylations of substituted enamides by aryl iodides were achieved for the first time via an unusual PdCl2(COD)/Ag3PO4 catalytic system. A broad range of (Z)-ß-amido-ß-arylacrylates were prepared regio- and stereoselectively in a highly efficient manner.

[Expression of matrixmetalloproteinase-8 on the bell-stage in human and rat tooth development].

OBJECTIVE: To study the expression of MMP-8 in human and rat tooth development. METHODS: Immunohistochemistry was used to detect the localization of MMP-8 protein while in situ hybridization was used to examine the expression of MMP-8 mRNA. RESULTS: The expression of MMP-8 protein was localized in odontoblast and dentin matrix at the later bell stage in human tooth germ. The dentin was denser close to the pulp cavity. The expression of MMP-8 mRNA was found in very few polarized odontoblast at the early bell stage and all polarized odontoblast at the later bell stage in rat tooth germ. CONCLUSION: The results suggested that MMP-8 involved in dentin matrix rebuilding in the process of dentin formation in human and rat dental development.

Expression of matrixmetalloproteinase-8 on the bell-stage in human and rat tooth development / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the expression of MMP-8 in human and rat tooth development.</p><p><b>METHODS</b>Immunohistochemistry was used to detect the localization of MMP-8 protein while in situ hybridization was used to examine the expression of MMP-8 mRNA.</p><p><b>RESULTS</b>The expression of MMP-8 protein was localized in odontoblast and dentin matrix at the later bell stage in human tooth germ. The dentin was denser close to the pulp cavity. The expression of MMP-8 mRNA was found in very few polarized odontoblast at the early bell stage and all polarized odontoblast at the later bell stage in rat tooth germ.</p><p><b>CONCLUSION</b>The results suggested that MMP-8 involved in dentin matrix rebuilding in the process of dentin formation in human and rat dental development.</p>

[An immunohistochemical study of the effects of excessive fluoride on type I collagen in rat developmental dentine].

OBJECTIVE: To study the effects of excessive fluoride on type I collagen in rat developmental dentine. METHODS: Eighty SD rats, 5 days old, were divided into experimental and control groups, 40 in each group. The experimental group received subcutaneous injection of 0.2% NaF every 4 days (the dose was 2 mg NaF per kg body wt). The same volume of 0.9% NaCl was used in the control. Twenty rats in each group were killed 4 days after the second and the seventh injection respectively. The expression of type I collagen was assayed with immunohistochemical technique. RESULTS: 4 out of 20 rats after two injections showed abnormal distribution of type I collagen (dense stain of collagen in the odontoblast, aggregation of collagen in the dentine and disordered arrangement of collagen in the predentine; All 20 rats after seven injections showed abnormal distribution of type I collagen. CONCLUSION: Excessive fluoride may affect the metabolism of type I collagen in rat developmental dentine.

An immunohistochemical study of the effects of excessive fluoride on type I collagen in rat developmental dentine / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effects of excessive fluoride on type I collagen in rat developmental dentine.</p><p><b>METHODS</b>Eighty SD rats, 5 days old, were divided into experimental and control groups, 40 in each group. The experimental group received subcutaneous injection of 0.2% NaF every 4 days (the dose was 2 mg NaF per kg body wt). The same volume of 0.9% NaCl was used in the control. Twenty rats in each group were killed 4 days after the second and the seventh injection respectively. The expression of type I collagen was assayed with immunohistochemical technique.</p><p><b>RESULTS</b>4 out of 20 rats after two injections showed abnormal distribution of type I collagen (dense stain of collagen in the odontoblast, aggregation of collagen in the dentine and disordered arrangement of collagen in the predentine; All 20 rats after seven injections showed abnormal distribution of type I collagen.</p><p><b>CONCLUSION</b>Excessive fluoride may affect the metabolism of type I collagen in rat developmental dentine.</p>