Ionothermal Synthesis of Metal Chalcogenides M2Ag3Sb3S7 (M = Rb, Cs) Displaying Nonlinear Optical Activity in the Infrared Region.

Two interesting non-centrosymmetric metal chalcogenides, Rb2Ag3Sb3S7 and Cs2Ag3Sb3S7, were synthesized by an ionothermal approach. Crystals of compounds Rb2Ag3Sb3S7 and Cs2Ag3Sb3S7 possess isomorphic configuration, consisting of two-dimensional (2D) anionic networks ∞[Ag3Sb3S7]2-, which are split by alkali-metal M+ cations. The band gaps are 2.11 and 2.02 eV for Rb2Ag3Sb3S7 and Cs2Ag3Sb3S7, respectively. Second-harmonic generation (SHG) studies revealed that Rb2Ag3Sb3S7 affords a powder SHG performance of ∼0.5 × AgGaS2 with type-I phase matching, while Cs2Ag3Sb3S7 shows a slightly stronger SHG performance of ∼0.6 × AgGaS2 with type-I phase matching. Both compounds possess broad transparency ranges (∼0.6-20 µm), suggesting their potential as infrared (IR) nonlinear optical (NLO) materials. The laser damage thresholds (LDTs) of both Rb2Ag3Sb3S7 and Cs2Ag3Sb3S7 are about 2.3 × AgGaS2. The calculated birefringence indexes Δn are 0.1885 and 0.1944 at 1.064 µm, respectively, which are sufficiently large enough to achieve phase matching. Theoretical studies using density functional theory have been implemented to further understand the relationship between their NLO properties and band structures.

Pressure-Induced Superconductivity and Flattened Se6 Rings in the Wide Band Gap Semiconductor Cu2I2Se6.

The two major classes of unconventional superconductors, cuprates and Fe-based superconductors, have magnetic parent compounds, are layered, and generally feature square-lattice symmetry. We report the discovery of pressure-induced superconductivity in a nonmagnetic and wide band gap 1.95 eV semiconductor, Cu2I2Se6, with a unique anisotropic structure composed of two types of distinct molecules: Se6 rings and Cu2I2 dimers, which are linked in a three-dimensional framework. Cu2I2Se6 exhibits a concurrent pressure-induced metallization and superconductivity at ∼21.0 GPa with critical temperature (Tc) of ∼2.8 K. The Tc monotonically increases within the range of our study reaching ∼9.0 K around 41.0 GPa. These observations coincide with unprecedented chair-to-planar conformational changes of Se6 rings, an abrupt decrease along the c-axis, and negative compression within the ab plane during the phase transition. DFT calculations demonstrate that the flattened Se6 rings within the CuSe layer create a high density of states at the Fermi level. The unique structural features of Cu2I2Se6 imply that superconductivity may emerge in anisotropic Cu-containing materials without square-lattice geometry and magnetic order in the parent compound.

A new method for the preparation of a [Sn2(H2PO2)3]Br SHG-active polar crystal via surfactant-induced strategy.

Herein, unprecedented NLO-brominated tin hypophosphites, namely [Sn2(H2PO2)3]Br, were discovered via a facile surfactant-induced method, which displayed a moderate powder SHG intensity (3.0 × KDP) in type - I phase matching behavior. This complex has high chemical and thermal stability at room temperature. DFT calculations and SHG coefficient analyses revealed that the alignment of the SHG-active-units SnO3 trigonal pyramids and Br- anions in its structure mainly contribute to the macroscopical SHG behaviors.

(enH2)(4.5)[In(As(V)S4)3][As2(III)(µ-S2)S3]Cl and (enH2)MnAs(III)As(V)S6: two thioarsenates(III, V) with mixed-valent optical properties.

Two mixed-valent thioarsenates, namely (enH2)(4.5)[In(As(V)S4)3][As2(III)(µ-S2)S3]Cl (1) and (enH2)MnAs(III)As(V)S6 (2) (en = ethylenediamine), have been solvothermally synthesized and characterized. Thermal stability, magnetic and mixed-valent optical properties, as well as theoretical band structures and DOSs, of 1 and 2 have also been studied.

Structural, electronic, and linear optical properties of organic photovoltaic PBTTT-C14 crystal.

Poly(2,5-bis(3-tetradecylthiophen-2yl)thieno(3,2-b)thiophene) (PBTTT-C14) is an important electro-optical polymer, whose three-dimensional crystal structure is somewhat ambiguous and the fundamental electronic and linear optical properties are not well known. We carried out first-principles calculations to model the crystal structure and to study the effect of side-chains on the physical structure and electronic properties. Our calculations suggest that the patterns of side-chain has little direct effect on the valence band maximum and conduction band minimum but they do have impact on the bandgap through changing the π-π stacking distance. By examining the band structure and wave functions, we conclude that the fundamental bandgap of the PBTTT-C14 crystal is determined by the conduction band energy at the Q point. The calculations indicate that the bandgap of PBTTT-C14 crystal may be tunable by introducing different side-chains. The significant peak in the imaginary part of the dielectric function arises from transitions along the polymer backbone axis, as determined by the critical-point analysis and the large optical transition matrix elements in the direction of the backbone.

A clinical study of weining granules in the treatment of gastric precancerous lesions.

OBJECTIVE: To investigate the clinical effects of Weining granules on gastric precancerous lesions (GPLs). METHODS: 120 patients with GPLs were randomly assigned in a 1:1 ratio to receive Weining granules (trial group) or the comparator Weifuchun tablets (control group) for 6 months. Outcomes were compared between the two groups including: overall response; gastroscopically-determined response; pathologically-confirmed response; eradication of Helicobacter pylori (HP); microvessel density (MVD) in the gastric mucosa; expression of vascular endothelial growth factor (VEGF); interleukin 2 (IL-2); interleukin 6 (IL-6); T lymphocyte subsets; immunoglobulins; symptom scores; quality of life (QOL); and adverse reactions. RESULTS: Patients in the trial group had a significantly higher (P < 0.05) overall response rate (81.7%) as compared with those in the control group (63.3%). Relative to treatment with Weifuchun tablets treatment with Weining granules resulted in a significant improvement (P < 0.05) in the scores for gastric pain, distension and stuffiness in the hypochondrium, and anorexia. As compared with the tablets the granules were associated with a significantly higher overall gastroscopically-determined response rate (78.3%; P < 0.05). Pathological examination of tissue samples indicated that 61.7% of patients receiving the granules were cured with an overall response rate of 75.5%; these rates were significantly higher than in the control group (P < 0.05). In comparison with patients receiving the tablets, those given the granules were significantly more likely to have their HP eradicated (75.0% vs. 51.4%; P < 0.05). Improvements in MVD, VEGF, CD4+, CD4+/ CD8+, IL-2, IL-6 and IgG were significantly greater with the Weining Granules than with the Weifuchun tablets (P < 0.05 or P < 0.01). After follow-up of 1 year, 17.5% of patients in the trial group relapsed as compared with 39.5% in the control group (P < 0.05). Relative to the control group, the trial group showed significantly greater improvements in physical, psychological and social relationships, and in environmental domains (P < 0.05 or P < 0.01). No significant adverse reactions were observed during treatment. CONCLUSION: The Weining granules appear to be effective in improving the gastric precancerous state and the main symptoms, in inhibiting angiogenesis, enhancing immune function and QOL, and in reducing 1-year relapses. In addition, this preparation seems to be associated with a low risk of adverse events, making it a safe and efficacious option for the treatment of GPLs.

Diverse closed cavities in condensed rare earth metal-chalcogenide matrixes: Cs[Lu7Q11] and (ClCs6)[RE21Q34] (RE = Dy, Ho; Q = S, Se, Te).

Two types of novel ordered chalcogenids Cs[Lu(7)Q(11)] (Q = S, Se) and (ClCs(6))[RE(21)Q(34)] (RE = Dy, Ho; Q = S, Se, Te) were discovered by high-temperature solid state reactions. The structures were characterized by single-crystal X-ray diffraction data. Cs[Lu(7)Q(11)] crystallize in the orthorhombic Cmca (no. 64) with a = 15.228(4)-15.849(7) Å, b = 13.357(3)-13.858(6) Å, c = 18.777(5)-19.509(8) Å, and Z = 8. (ClCs(6))[RE(21)Q(34)] crystallize in the monoclinic C2/m (no. 12) with a = 17.127(2)-18.868(2) Å, b = 19.489(2)-21.578(9) Å, c = 12.988(9)-14.356(2) Å, ß = 128.604(2)-128.738(4)°, and Z = 2. Both types of compounds feature 3D RE-Q network structures that embed with dual tricapped cubes Cs(2)@Se(18) in the former or unprecedented matryoshka nesting doll structure cavities of (ClCs(6))@Se(32) in the latter. The band gap, band structure, as well as a structure change trend of the majority of A/RE/Q compounds are presented.

[Ni(phen)3]2Sb18S29: a novel three-dimensional framework thioantimonate(III) templated by [Ni(phen)3] complexes.

A novel thioantimonate(III), namely, [Ni(phen)(3)](2)Sb(18)S(29) (1; phen = 1,10-phenanthroline), has been solvothermally synthesized. Its structure features a three-dimensional framework with the largest channels in thioantimonates. The chiral [Ni(phen)(3)](2+) cations and the Sb:S ratio (1:1.611) in 1 are unique among those in the reported thioantimonates. The thermal stability, optical properties, and electric conductivity as well as the theoretical band structure and density of state of 1 have also been studied.

Structure change induced by terminal sulfur in noncentrosymmetric La2Ga2GeS8 and Eu2Ga2GeS7 and nonlinear-optical responses in middle infrared.

Two new noncentrosymmetric quaternary sulfides, La(2)Ga(2)GeS(8) (1) and Eu(2)Ga(2)GeS(7) (2), have been synthesized by high-temperature solid-state reactions. The structure change on going from 1 to 2 to the known Li(2)Ga(2)GeS(6) (3) nicely shows that the reduced cation charge-compensation requirement causes a decrease in the number of terminal S atoms per formula, which is a key to determining the connectivity of the GaS(4) and GeS(4) building units. Powder sample 2 exhibits a strong second-harmonic-generation (SHG) response of about 1.6 times the benchmark AgGaS(2) at 2.05 µm laser radiation, a non type I phase-matchable behavior, and a comparable transparency region. The SHG intensities of these compounds originate from the electronic transitions from S 3p states to La/Eu/Li-S, Ga-S, and Ge-S antibonding states according to Vienna ab initio simulation package studies.

In-phase alignments of asymmetric building units in Ln4GaSbS9 (Ln = Pr, Nd, Sm, Gd-Ho) and their strong nonlinear optical responses in middle IR.

New noncentrosymmetric rare-earth metal gallium thioantimonates, Ln(4)GaSbS(9) were synthesized from stoichiometric element mixtures at 950 °C by high-temperature solid-state reactions. These compounds crystallize in orthorhombic space group Aba2 (no.41) with a = 13.799(3)-13.427(5) Å, b = 14.187(3)-13.756(5) Å, c = 14.323(3)-13.954(5) Å, V = 2804(2)-2577 (2) Å(3), and Z = 8 on going from Ln = Pr to Ho. The asymmetric building units, bimetallic polar (Sb(2)S(5)) units, and dimeric (GaS(4))(2) tetrahedra are in-phase aligned as an infinite single anionic chain of {[(Ga(2)S(6))(Sb(2)S(5))](10-)}(∞) that is further packed in a noncentrosymmetric pseudolayer motif perpendicular to the c axis. Three of the title compounds show large powder second harmonic generation (SHG) effects at 2.05 µm, and two of them also exhibit large transparency ranges (1.75 or 0.75 to 25 µm) in the middle-IR region. Significantly, the Sm-member exhibits the strongest SHG response among sulfides to date with intensity approximately 3.8 times that of the benchmark AgGaS(2). The band structures, indirect band gap nature, bonding strengths, and lone pair effects around Sb have also been studied by Vienna ab initio simulation package calculations.

Pb2B5O9I: an iodide borate with strong second harmonic generation.

The combination of lone-pair effects on Pb(2+) cations and the smaller electronegativity of I(-) anions into the pentaborate framework generates a phase-matchable material, Pb(2)B(5)O(9)I, with the largest powder SHG response among borates, about 13.5 times that of KDP (KH(2)PO(4)), and transparency over the near-UV to middle-IR region. DFT calculations on electronic structure and cutoff-energy-dependent SHG coefficients confirm these origins.

Syntheses, crystal and electronic structures, and physical properties of quaternary semiconductors: Ln2Mn3Sb4S12 (Ln = Pr, Nd, Sm, Gd).

Four new quaternary lanthanide antimony sulfides: Ln(2)Mn(3)Sb(4)S(12) (Ln = Pr, Nd, Sm, Gd) have been synthesized from a stoichiometric element mixture at 1373 K by conventional solid state reactions. These compounds crystallize in the monoclinic space group C2/m with the unit cell parameters of a = 19.928(2)-19.9672(6) A, b = 3.9323(4)-3.8803(2) A, c = 14.921(2)-14.9011(1) A, V = 938.5(2)-925.63(6) A(3), and Z = 2 on going from Ln = Pr to Gd. Their structure represents a novel wavy MnS(6) octahedron layer decorated on both sides by chains of an SbS(5) square pyramid via strong Sb-S bonding interactions (< 3.0 A). Such a MnS(6) octahedron layer consists of chains of an edge-sharing [Mn1S(6)](2) dimer extending along [010] that are interconnected by single strings of an edge-sharing Mn2S(6) octahedron at axial S apexes. Sm(2)Mn(3)Sb(4)S(12) displays spin-canted antiferromagnetic interactions between Sm(2+) and Mn(2+) centers and an optical gap of 1.50 eV. The DFT study indicates an indirect band gap with an electronic transfer excitation of S 3p to Sb 5p orbital electrons.

Syntheses, crystal and electronic structures, and physical properties of two quaternary chalcogenides: La(4)FeSb(2)Q(10) (Q = S, Se).

Two new quaternary chalcogenides, La(4)FeSb(2)S(10) and La(4)FeSb(2)Se(10), have been synthesized from the stoichiometric mixture of elements by solid-state reactions at 1100 degrees C. The compounds crystallize in the orthorhombic space group Pbcm with a = 15.066(4) A, b = 7.590(2) A, c = 13.341(4) A, and Z = 4 and a = 15.596(5) A, b = 7.869(2) A, c = 13.960(4) A, and Z = 4, respectively. These structures represent an unique three-dimensional network, in which SbQ(3) trigonal pyramids (Sb-S < 2.60 A, Sb-Se < 2.80 A) are connected via a relatively weak Sb-Q bond (Sb-S approximately 2.90 A, Sb-Se approximately 3.00 A) in a novel teeter-totter (SbQ(4))(n) chain motif. The theoretical studies confirm the Sb-Q bonding interactions within such teeter-totter chains. Their optical band gaps are measured to be 1.00 and 0.85 eV. At room temperature, their electrical conductivities are about 10(-4) S/cm. Both compounds display antiferromagnetic interactions between Fe centers, and their effective magnetic moments are 5.25 and 6.17 micro(B), respectively.

The antimony-based type I clathrate compounds Cs(8)Cd(18)Sb(28) and Cs(8)Zn(18)Sb(28).

In phase: The title compounds lie in a new region of phase space for such a structure, and have stoichiometries in accord with a classical Zintl phase formulation. The small semiconductor gaps indicated by DFT calculations are also supported by their diamagnetic susceptibilities.

Eu3Co2In15 and KM2In9 (M = Co, Ni): 3D frameworks based on transition metal centered In9 clusters.

The title three compounds have been synthesized by solid state reactions at high temperatures, with excess indium as flux, and structurally characterized by single-crystal X-ray diffraction studies. Eu(3)Co(2)In(15) forms a new structure type and crystallizes in the tetragonal space group P4/mbm (No. 127), whereas KM(2)In(9) (M = Co, Ni) in the BaFe(2)Al(9) type crystallizes in the hexagonal space group P6/mmm (No. 191). Their structures all feature a three-dimensional anionic framework based on 1D [MIn(6)] single cluster chains composed of face-sharing [MIn(9)] clusters. In Eu(3)Co(2)In(15), two adjacent [CoIn(6)] single cluster chains form a [Co(2)In(11)] double cluster chain via corner-sharing In atoms as well as In-In bonds; the latter chains are further interconnected by additional indium atoms via In-In bonds into a complicated 3D framework, forming two types of tunnels along the c-axis, which are filled by the europium atoms. In KM(2)In(9), the [MIn(6)] single cluster chains are directly interconnected via corner sharing and exo In-In bonds into a 3D framework with the K(+) ions encapsulated in the 1D tunnels along the c-axis. Band structure calculations of three compounds based on density functional theory methods indicate that all three compounds are metallic.

Synthesis, properties, and theoretical studies of new stepwise layered iodoplumbate: [Ni(opd)2(acn)2]n[Pb4I10]n.

A novel 2D layered iodoplumbate, [Ni(opd)(2)(acn)(2)](n)[Pb(4)I(10)](n) (1), yellow-green in color, has been synthesized. The anionic [Pb(4)I(10)(2-)](n) layer is comparable to the hexagonal PbI(2) sheet but in a lower symmetry. Although the intercalated cations contribute negligibly to the electron transition, they induce the reconstruction of the inorganic moiety, which leads to a band-gap blue shift with respect to that of PbI(2).

Structures and physical properties of rare-earth zinc antimonides Pr6Zn(1+x)Sb(14+y) and RE6Zn(1+x)Sb14 (RE = Sm, Gd-Ho).

A new series of isostructural ternary rare-earth zinc antimonides RE(6)Zn(1+x)Sb(14+y) (RE = Pr, Sm, Gd-Ho) has been obtained by direct reaction of the elements at 1050-1100 degrees C. Single-crystal X-ray diffraction studies revealed that these compounds adopt an orthorhombic structure type (space group Immm (no. 71), Z = 2, a = 4.28-4.11 A, b = 15.15-14.73 A, c = 19.13-18.56 A in the progression from RE = Pr to Ho) that may be regarded as stuffed variants of a (U(0.5)Ho(0.5))(3)Sb(7)-type host structure. Columns of face-sharing RE(6) trigonal prisms, centered by Sb atoms, occupy channels defined by an extensive polyanionic Sb network. This network is constructed from three-atom-wide and four-atom-wide Sb strips, the latter being linked together by single Sb atoms in RE(6)Zn(1+x)Sb(14) (RE = Sm, Gd-Ho; y = 0), but also by additional Sb-Sb pairs in a disordered fashion in Pr(6)Zn(1+x)Sb(14+y) (y = approximately 0.6). Interstitial Zn atoms then partially fill tetrahedral sites (occupancy of 0.5-0.7) and, to a lesser extent, square pyramidal sites (occupancy of 0.04-0.12), accounting for the observed nonstoichiometry with variable x. Except for the Gd member, these compounds undergo antiferromagnetic ordering below T(N) < 9 K, with the magnetic susceptibilities of the Tb, Dy, and Ho members following the Curie-Weiss law above T(N). For the Ho member, the thermal conductivities are low and the Seebeck coefficients are small and positive, implying p-type character consistent with the occurrence of partial Zn occupancies. At low temperatures (down to 5 K), electrical resistivity measurements for the Tb, Dy, and Ho members indicated metallic behavior, which persists at high temperatures (up to 560 K) for the Ho member. Band structure calculations on an idealized "Gd(6)Zn(2)Sb(14)" model revealed the existence of a pseudogap near the Fermi level.

Adrenalectomy potentiates noradrenergic suppression of GABAergic transmission in parvocellular neurosecretory neurons of hypothalamic paraventricular nucleus.

Glucocorticoids are known to regulate both the noradrenergic and GABAergic inputs to the paraventricular nucleus (PVN). However, little is known about the effects of glucocorticoids on the interaction of these two input systems. Here we examined the effects of bilateral adrenalectomy (ADX) on the noradrenergic modulation of GABAergic transmission in the type II PVN neurons labeled with a retrograde dye injected into the pituitary stalk. Noradrenaline either reduced or augmented the frequency of spontaneous inhibitory postsynaptic current (sIPSC) without changing the amplitude and decay time constant. These effects were blocked by alpha2A- and alpha(1A/1L)-adrenoceptor antagonists, respectively. ADX increased the proportion of the neurons showing the noradrenergic reduction and the extent of reduction in the IPSC frequency. The ADX-induced changes were reversed by supplementation of ADX rats with corticosterone (10-mg pellet). ADX also potentiated the noradrenergic reduction in the frequency of miniature IPSC and paired-pulse facilitation of evoked IPSC. BRL 44408 (3 microM), a alpha2A-adrenoceptor antagonist, blocked the noradrenergic reduction in ADX rats. Corticotropin-releasing hormone and/or vasopressin transcripts were detected in neurons displaying noradrenergic augmentation or reduction of IPSC frequency. ADX enhanced the proportion of neurons expressing corticotropin-releasing hormone. Collectively, the results suggest that depletion of corticosterone by ADX markedly potentiates the noradrenergic suppression of GABAergic transmission mediated by the alpha2A-adrenoceptors on the GABAergic terminals in the parvocellular neurosecretory PVN neurons. These results may provide a novel synaptic mechanism for the glucocorticoid-induced plasticity in the noradrenergic modulation of neuroendocrine function of the PVN.

Noradrenaline excites and inhibits GABAergic transmission in parvocellular neurons of rat hypothalamic paraventricular nucleus.

Noradrenaline (NA) is a major neurotransmitter that regulates many neuroendocrine and sympathetic autonomic functions of the hypothalamic paraventricular nucleus (PVN). Previously NA has been shown to increase the frequency of excitatory synaptic activity of parvocellular neurons within the PVN, but little is known about its effects on inhibitory synaptic activity. In this work, we studied the effects of NA (1-100 microM) on the spontaneous inhibitory synaptic currents (sIPSC) of type II PVN neurons in brain slices of the rat using the whole cell patch-clamp technique. Spontaneous IPSCs were observed from most type II neurons (n = 121) identified by their anatomical location within the PVN and their electrophysiological properties. Bath application of NA (100 microM) increased sIPSC frequency by 256% in 59% of the neurons. This effect was blocked by prazosin (2-20 microM), the alpha(1)-adrenoceptor antagonist and mimicked by phenylephrine (10-100 microM), the alpha(1)-adrenoceptor agonist. However, in 33% of the neurons, NA decreased sIPSC frequency by 54%, and this effect was blocked by yohimbine (2-20 microM), the alpha(2)-adrenoceptor antagonist and mimicked by clonidine (50 microM), the alpha(2)-adrenoceptor agonist. The Na(+) channel blocker, tetrodotoxin (0.1 microM) blocked the alpha(1)-adrenoceptor-mediated effect, but not the alpha(2)-adreonoceptor-mediated one. Both of the stimulatory and inhibitory effects of NA on sIPSC frequency were observed in individual neurons when tested with NA alone, or both phenylephrine and clonidine. Furthermore, in most neurons that showed the stimulatory effects, the inhibitory effects of NA were unmasked after blocking the stimulatory effects by prazosin or tetrodotoxin. These data indicate that tonic GABAergic inputs to the majority of type II PVN neurons are under a dual noradrenergic modulation, the increase in sIPSC frequency via somatic or dendritic alpha(1)-adrenoceptors and the decrease in sIPSC frequency via axonal terminal alpha(2)-adrenoceptors on the presynaptic GABAergic neurons.