Recent advances in electrocatalytic nitrite reduction.

Electrocatalytic nitrite reduction is of great significance for wastewater treatment and value-added chemicals synthesis. This review highlights the latest progress in electrochemical nitrite reduction to produce two types of products, including gaseous products (NO, N2O, N2) and liquid products (NH2OH and NH4+). The heterogeneous and homogeneous catalysts used in the corresponding reduction processes are introduced, with emphasis on the product selectivity regulation and reaction mechanism understanding. Finally, the challenges and opportunities in this field are analyzed as well. This review can provide guidelines for designing electrochemical systems with high efficiency and specificity for nitrite reduction.

[Research on enhancement of mental rotation ability based on transcranial direct current stimulation].

Transcranial direct current stimulation (tDCS) is a non-invasive low-current brain stimulation technique, which is mainly based on the different polarity of electrode stimulation to make the activation threshold of neurons different, thereby regulating the excitability of the cerebral cortex. In this paper, healthy subjects were randomly divided into three groups: anodal stimulation group, cathodal stimulation group and sham stimulation group, with 5 subjects in each group. Then, the performance data of the three groups of subjects were recorded before and after stimulation to test their mental rotation ability, and resting state and task state electroencephalogram (EEG) data were collected. Finally, through comparative analysis of the behavioral data and EEG data of the three groups of subjects, the effect of electrical stimulation of different polarities on the three-dimensional mental rotation ability was explored. The results of the study found that the correct response time/accuracy rate and the accuracy rate performance of the anodal stimulation group were higher than those of the cathodal stimulation and sham stimulation groups, and there was a significant difference ( P < 0.05). The alpha wave power analysis found that the mental rotation mainly activates the frontal lobe, central area, parietal lobe and occipital lobe. In the anodal stimulation group, the alpha wave power changed significantly in the frontal lobe and occipital lobe ( P < 0.05). The results of this paper show that anodal stimulation group can improve the mental rotation ability of the subjects to a certain extent. The results of this paper can provide important theoretical support for further research on the mechanism of tDCS on mental rotation ability.

[Review of cognitive enhancement techniques based on the combination of cognitive training and transcranial direct current stimulation].

Cognitive enhancement refers to the technology of enhancing or expanding the cognitive and emotional abilities of people without psychosis based on relevant knowledge of neurobiology. The common methods of cognitive enhancement include transcranial direct current stimulation (tDCS) and cognitive training (CT). tDCS takes effect quickly, with a short effective time, while CT takes longer to work, requiring several weeks of training, with a longer effective time. In recent years, some researchers have begun to use the method of tDCS combined with CT to regulate the cognitive function. This paper will sort out and summarize this topic from five aspects: perception, attention, working memory, decision-making and other cognitive abilities. Finally, the application prospect and challenges of technology are prospected.

[Integrin α5 silencing inhibits proliferation, invasion and metastasis of human liver cancer Bel-7404 cells in vitro].

OBJECTIVE: To analyze the association of integrinα5 (ITGA5) with grading of liver cancer and the overall patient survival and investigate the effects of integrin α5 (ITGA5) silencing on the proliferation, invasion and migration abilities of human liver cancer Bel-7404 cells. METHODS: UALCAN was used to analyze the expression of ITGA5 in liver cancer tissues and normal tissues, and expression in different grades of liver cancer tissues. GEPIA was used to analyze the relationship between ITGA5 expression and the survival of liver cancer patients through.The ITGA5 shRNA lentiviral vector was used to infect Bel-7404 cells to establish a cell line with stable ITGA5 silencing verified by Western blotting. Plate clone formation assay and Transwell assay were used to detect the proliferation, invasion and migration of Bel-7404 cells. The correlation between ITGA5 and PI3K in liver cancer tissues and control tissues was analyzed using Oncomine cancer specimen database. RESULTS: The expression of ITGA5 was significantly higher in liver cancer than in normal tissues (P < 0.05). The expression of ITGA5 was significantly lower in grade 1 than in grade 2 liver cancer, and also lower in grade 2 than in grade 3 liver cancer (P < 0.05). The patients with high ITGA5 expression had a significantly lower overall survival rate than those with low ITGA5 expression (P < 0.05). Plate clone formation assay showed that the clone formation rate was significantly lowered in Bel-7404 cells with ITGA5 silencing compared with the blank and negative control cells (P < 0.05). ITGA5 silencing significantly attenuated the migration of Bel-7404 cells as shown by Transwell assay (P < 0.05). ITGA5 and PI3K were both highly expressed and showed a positive correlation in liver cancer tissues (P < 0.05). CONCLUSIONS: ITGA5 is closely related to the progression of liver cancer and the patients' prognosis. ITGA5 silencing inhibits the proliferation, invasion and migration of liver cancer cells. ITGA5 promotes the liver cancer growth and metastasis possibly by regulating the PI3K signaling pathway.

Distributed measurements of external force induced local birefringence in spun highly birefringent optical fibers using polarimetric OFDR.

We develop a local birefringence determination method of measuring the distribution of external force-induced birefringence in spun high-birefringence (HiBi) fiber (spun HiBi fiber) using polarimetric optical frequency domain reflectometry (P-OFDR). By constructing the similarity between the measured Mueller matrices and fiber under test (FUT) matrices using two input states of polarization, the total phase retardance caused by the local birefringence of FUT can be determined from the trace of the measured matrices. We measure the local birefringence of spun HiBi fibers from two different manufacturers and telecom SMF (G652.D) caused by bending, twist, and transverse stress using our presented P-OFDR system. From the experimental results, we find that bending- and twist-induced birefringences of spun HiBi fiber are much lower than those of standard SMF. More remarkably, the coating package influences the transverse stress induced birefringence of spun HiBi fibers significantly. These experimental results verify that our presented method is beneficial to evaluating and improving spun HiBi fibers' quality.

Water-dispersible Hollow Microporous Organic Network Spheres as Substrate for Electroless Deposition of Ultrafine Pd Nanoparticles with High Catalytic Activity and Recyclability.

Microporous organic networks (MONs) have been considered as an ideal substrate to stabilize active metal nanoparticles. However, the development of highly water-dispersible hollow MONs nanostructures which can serve as both the reducing agent and stabilizer is highly desirable but still challenging. Here we report a template-assisted method to synthesize hollow microporous organic network (H-MON) spheres using silica spheres as hard template and 1,3,5-triethynylbenzene as the building blocks through a Glaser coupling reaction. The obtained water-dispersible H-MON spheres bearing sp- and sp2 -hybridized carbon atoms possess a highly conjugated electronic structure and show low reduction potential; thus, they can serve as a reducing agent and stabilizer for electroless deposition of highly dispersed Pd clusters to form a Pd/H-MON spherical hollow nanocomposite. Benefitting from their high porosity, large surface area, and excellent solution dispersibility, the as-prepared Pd/H-MON hollow nanocomposite exhibits a high catalytic performance and recyclability toward the reduction of 4-nitrophenol.

A Heterogeneous Photocatalytic Hydrogen Evolution Dyad: [(tpy.

The development of an artificial heterogeneous dyad by covalently anchoring a hydrogen-evolving molecule catalyst to a semiconductor photosensitizer through a bridging ligand is highly challenging. Herein, we adopt the inorganic-organic hybrid CdS-DETA NSs (DETA=diethylenetriamine, NSs=nanosheets) as initial matrix to successfully construct an imine bond (-CH=N-) linked heterogeneous dyad [CdS-N=CH-Ni] through the condensation reaction between the amino groups of CdS-DETA and the aldehyde group of the water reduction molecular catalyst, [(tpy-CHO)2 Ni]Cl2 (tpy=terpyridine). The [CdS-N=CH-Ni] enables a turnover number (TON) of about 43 815 versus Ni catalysts and an initial turnover frequency (TOF) of approximately 0.47 s-1 in 26 h under visible-light irradiation (λ>420 nm). The apparent quantum yield (AQY) reaches (9.9±0.8) % at 420 nm. Under optical conditions, the [CdS-N=CH-Ni] can achieve a considerable amount of hydrogen production, 507.1±27 µmol H2 for 6 h, which is 1.27 times that generated from the mechanically mixed system of CdS-DETA NSs and [(tpy-CH=NR)2 Ni]Cl2 (III) under otherwise identical conditions. Furthermore, its TON value based on Ni species is also higher than that of the mixed system of CdS-DETA and III.

Ligand design for alkali-metal-templated self-assembly of unique high-nuclearity CuII aggregates with diverse coordination cage units: crystal structures and properties.

The construction of two unique, high-nuclearity Cu(II) supramolecular aggregates with tetrahedral or octahedral cage units, [(mu(3)-Cl)[Li subset Cu(4)(mu-L(1))(3)](3)](ClO(4))(8)(H(2)O)(4.5) (1) and [[Na(2) subset Cu(12)(mu-L(2))(8)(mu-Cl)(4)](ClO(4))(8)(H(2)O)(10)(H(3)O(+))(2)](infinity) (2) by alkali-metal-templated (Li(+) or Na(+)) self-assembly, was achieved by the use of two newly designed carboxylic-functionalized diazamesocyclic ligands, N,N'-bis(3-propionyloxy)-1,4-diazacycloheptane (H(2)L(1)) or 1,5-diazacyclooctane-N,N'-diacetate acid (H(2)L(2)). Complex 1 crystallizes in the trigonal R3c space group (a = b = 20.866(3), c = 126.26(4) A and Z = 12), and 2 in the triclinic P1 space group (a = 13.632(4), b = 14.754(4), c = 19.517(6) A, alpha = 99.836(6), beta = 95.793(5), gamma = 116.124(5) degrees and Z = 1). By subtle variation of the ligand structures and the alkali-metal templates, different polymeric motifs were obtained: a dodecanuclear architecture 1 consisting of three Cu(4) tetrahedral cage units with a Li(+) template, and a supramolecular chain 2 consisting of two crystallographically nonequivalent octahedral Cu(6) polyhedra with a Na(+) template. The effects of ligand functionality and alkali metal template ions on the self-assembly processes of both coordination supramolecular aggregates, and their magnetic behaviors are discussed in detail.

Preparation of acentric porous coordination frameworks from an interpenetrated diamondoid array through anion-exchange procedures: crystal structures and properties.

The formation, crystal structures, and properties of a series of three-dimensional (3-D) Cu(II) coordination polymers, [[Cu(L)2(H2O)2](PF6)2(H2O)(1.25)]n (1), [[CuL(N3)2](H2O)(1.5)]n (2), and [[CuL(H2O)(SO4)](H2O)2]n (3), with an angular bridging ligand 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L) are reported. Complex 1 crystallizes in the tetragonal I4(1)/a space group (a = b = 13.462(2) A, c = 46.47(1) A, Z = 8), complex 2 in the orthorhombic Pna2(1) space group (a = 6.379(2) A, b = 10.060(3) A, c = 27.232(9) A, Z = 4), and complex 3 in the orthorhombic P2(1)2(1)2(1) space group (a = 5.510(2) A, b = 10.576(4) A, c = 28.34(1) A, Z = 4). Different polymeric frameworks are obtained by only varying the counterions. These include the 2-fold interpenetrated diamondoid structure of 1, the acentric alpha-Po network of 2, and the chiral open framework of 3 with (6(3)).(6(9).8) topology. The interesting anion-exchange, porous, and magnetic properties of these coordination supramolecules have been investigated in detail.

From metallacyclophanes to 1-D coordination polymers: role of anions in self-assembly processes of copper(II) and 2,5-bis(3-pyridyl)-1,3,4-oxadiazole.

The reaction of various CuII salts with 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L) in CH3CN-H2O medium affords different complexes, the solid structures of which are controlled only by the choice of the counteranions. Reaction of Cu-(ClO4)2.6H2O or Cu(NO3)2.3H2O and L yields the novel bimetallic macrocyclic complex [Cu2L2(H2O)6](ClO4)4(H2O)4 (1) [monoclinic, space group P21/m, a = 8.745(5) A, b = 16.179(10) A, c = 14.930(8) A, beta = 93.253(10) degrees, Z = 2] or [CuL(NO3)2]2(CH3CN)2 (2) [triclinic, space group P1, a = 7.863(3) A, b = 8.679(3) A, c = 13.375(5) A, alpha = 74.121(5) degrees, beta = 78.407(6) degrees, gamma = 86.307(6) degrees, Z = 1]. However, with the replacement of CuII perchlorate or nitrate salts with CuSO4.5H2O or Cu(OAc)2.H2O in the above reaction, two different one-dimensional (1-D) coordination polymers [[Cu2L2(H2O)6(SO4)2](H2O)6]n (3) [triclinic, space group P1, a = 7.078(3) A, b = 11.565(4) A, c = 12.561(5) A, alpha = 109.511(6) degrees, beta = 105.265(6) degrees, gamma = 94.042(6) degrees, Z = 1] or [[Cu2L(mu-OAc)4]]n (4) [monoclinic, space group C2/c, a = 20.007(7) A, b = 7.506(2) A, c = 16.062(5) A, beta = 108.912(5) degrees, Z = 4] were obtained. These results unequivocally indicate that the nature of the counteranions, which play different roles in each complex, is the key factor governing the structural topologies of them. The magnetic properties of these CuII complexes have been investigated by variable-temperature magnetic susceptibility and magnetization measurements, and the magneto-structural correlation has been analyzed in detail.

First Cu(II) diamondoid net with 2-fold interpenetrating frameworks. The role of anions in the construction of the supramolecular arrays.

The synthesis and crystal structure of the three-dimensional coordination polymer of an angular dipyridyl ligand 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L) and Cu(ClO(4))(2), exhibiting the first Cu(II) diamondoid network with 2-fold interpenetration, ([Cu(L)(2)(H(2)O)(2)](ClO(4))(OH)(H(2)O)(2.5))(n) (1), together with the Cu(OAc)(2) complex of L, [Cu(L)(2)(OAc)(2)(H(2)O)](H(2)O)(2)(CH(3)OH) (2), with an unexpected mononuclear structure, are reported. Crystal data for 1: tetragonal, space group I4(1)/a, a = b = 13.477(3) A, c = 46.167(13) A, Z = 8. Crystal data for 2: triclinic, space group P(-)1, a = 7.847(2) A, b = 13.189(4) A, c = 15.948(5) A, alpha = 75.225(7) degrees, beta = 79.945(6) degrees, gamma = 77.540(5) degrees, Z = 2. The magnetic properties and anion effect are also discussed.

First tetrameric NiII cluster with planar triangular topology exhibiting ferromagnetic pathways.

[Ni4L3(H2O)2](ClO4)2.2H2O 1, the first tetranuclear NiII cluster showing triangle planar geometry, formed with a new carboxylic-functionalized 1,5-diazacyclooctane bridging ligand has been presented; the global magnetic coupling is ferromagnetic and anisotropic calculations have been made.

New mononuclear, cyclic tetranuclear, and 1-D helical-chain Cu(II) complexes formed by metal-assisted hydrolysis of 3,6-di-2-pyridyl-1,2,4,5-tetrazine (DPTZ): crystal structures and magnetic properties.

The reactions of 3,6-di-2-pyridyl-1,2,4,5-tetrazine (DPTZ) with different Cu(II) salts generate two new ligands, 2,5-bis(2-pyridyl)-1,3,4-oxodiazole (L(1)) and N,N'-bis(alpha-hydroxyl-2-pyridyl)ketazine (H(2)L(2)), from the metal-assisted hydrolysis of DPTZ, and form three new complexes: a mononuclear complex [Cu(L(1))(2)(H(2)O)(2)] .2ClO(4) (1), a linear coordination polymer [Cu(L(1))(NO(3))(2)](8) (2), and a cyclic tetranuclear complex [Cu(4)(L(2))(2)(Im)(2)(NO(3))(4)(H(2)O)(2)] (3) (Im = imidazole). Crystal data for 1: space group P2(1)/n with a = 10.339(3) A, b = 10.974(2) A, c = 13.618(4) A, beta = 103.24(1) degrees, and Z = 2. Crystal data for 2: space group C2/c with a = 13.9299(14) A, b = 9.2275(9) A, c = 12.1865(13) A, beta = 111.248(2) degrees, and Z = 4. Crystal data for 3: space group P2(1)/n with a = 9.3422(14) A, b = 15.987(2) A, c = 13.963(2) A, beta = 108.587(3) degrees, and Z = 2. L(1) acts as a bidentate chelating ligand in 1 and as a bis-bidentate chelating ligand in 2 with the shortest intramolecular Cu...Cu distance of 6.093 A. L(2) is a hexadentate ligand to bridge four Cu(II) ions, forming an interesting neutral cyclic tetranuclear complex 3 with Cu...Cu distances varying from 4.484 to 9.370 A. The mechanism of the metal assisted hydrolysis of DPTZ is discussed in detail. Magnetic susceptibility measurements indicate that 2 shows weak ferromagnetic interaction (J = 2.85 cm(-1)) along the 1-D helical chain, and that 3 displays weak antiferromagnetic interaction (J = -1.19 cm(-1) for the N-N bridge) and ferromagnetic interaction (j = 0.11 cm(-1) for the O-C=N bridge) between the adjacent Cu(II) ions.