A New Modification of Tellurite Phosphate:β-Te3O3(PO4)2

A new modification of tellurite phosphate, β-Te3O3（PO4）2, has been synthesized under hydrothermal conditions and its crystal structure was determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group P21/n（No. 14）, with a = 11.115（5）, b = 4.7033（19）, c = 17.287（7） ？, β = 106.086（5）°, V = 868.3（6） ？3, Z = 4, P2 Te3 O11, Mr = 620.74, Dc = 4.748 g/cm3, μ（Mo Kα） = 10.438 mm–1 and F（000） = 1096. The final full-matrix least-squares refinement converged to R = 0.0227, wR = 0.0534 for 1984 observed reflections with I 〉 2σ（I）, and R = 0.0240, w R = 0.0540 for all data（2070） and S = 1.117. β-Te3O3（PO4）2 is polymorphic with the known α-Te3O3（PO4）2（Weil H. M. et al. Z. Anorg. Allg. Chem. 2003, 629, 1068-1072）. The crystal structure of β-Te3O3（PO4）2 features a three-dimensional（3D） network composed of Te6 O2220-hexanuclear clusters interconnected by PO4 groups. Te6 O22 hexanuclear cluster is built from three Te2 O8 dimers（edge-sharing TeO5 square pyramids） linked to each via sharing O-corners. The structure difference between α-and β-forms of Te3O3（PO4）2 lies in the polymerization of tellurite oxides TenOm. 1D infinite 1∞{[Te3 O11]10-} single chains are presented in α-Te3O3（PO4）2, while 0D discrete Te6 O22 hexanuclear clusters are observed for β-Te3O3（PO4）2. Moreover, thermal analyses, infrared spectra and UV-Vis-NIR diffuse reflectance are also presented.

Long-term Field Corrosion Monitoring in Supporting Structures of China Xiamen Xiangan Subsea Tunnel

Xiamen Xiangan Subsea Tunnel is the first undersea tunnel constructed in China. It has become the major undersea pathway connecting Xiamen Island and Xiangan District since its operation in 2010. The total length is 6.05 km with the undersea length of 4.2 km. In an effort to onsite-monitor reinforcement corrosion in concrete structures, the commercially available CorroWatch multiprobe sensors and ERE-20 reference electrodes were pre-embedded in the selected locations and positions of supporting structures during the tunnel constructions. The real-time data have been collected annually by onsite measurements for 6 years. In this paper, the feasibility of the onsite corrosion monitoring system and suitability of the measured parameters including corrosion current, potential and temperature are discussed based on the preliminary results. The measured typical cyclic-type variations in corrosion current and temperature with monitoring time might be related to the seasonal changes during the annual routine measurements. The widely scattered corrosion potentials that are fluctuated complicatedly reflected localized differences in the vicinity of rebar and concrete. These findings, along with the progressively ongoing research, will provide valuable information in structural durability for service life prediction of reinforced concrete structures exposed to marine environments.

Role of in-situ formed free carbon on electromagnetic absorption properties of polymer-derived SiC ceramics

In order to enhance dielectric properties of polymer-derived SiC ceramics,a novel single-source-precursor was synthesized by the reaction of an allylhydrido polycarbosilane(AHPCS)and divinyl benzene(DVB)to form carbon-rich SiC.As expected,the free carbon contents of resultant SiC ceramics annealed at 1600℃are significantly enhanced from 6.62 wt%to 44.67 wt%.After annealing at 900-1600℃,the obtained carbon-rich SiC ceramics undergo phase separation from amorphous to crystalline feature where superfine SiC nanocrystals and turbostratic carbon networks are dispersed in an amorphous SiC(O)matrix.The dielectric properties and electromagnetic(EM)absorption performance of as-synthesized carbon-rich SiC ceramics are significantly improved by increasing the structural order and content of free carbon.For the 1600℃ ceramics mixed with paraffin wax,the minimum reflection coefficient(RCmin)reaches-56.8 dB at 15.2 GHz with the thickness of 1.51 mm and a relatively broad effective bandwidth(the bandwidth of RC values lower than-10 dB)of 4.43 GHz,indicating the excellent EM absorption performance.The carbon-rich SiC ceramics have to be considered as harsh environmental EM absorbers with excellent chemical stability,high temperature,and oxidation and corrosion resistance.

2D graphene oxide-L-arginine-soybean lecithin nanogenerator for synergistic photothermal and NO gas therapy

Nitric oxide(NO) gas therapy has been regarded as a promising strategy for cancer treatment. However,its therapeutic efficiency is still unsatisfying due to the limitations of monotherapy. Previous preclinical and clinical studies have shown that combination therapy could significantly enhance therapeutic efficiency. Herein, a graphene oxide(GO)-L-arginine(L-Arg, a natural NO donor) hybrid nanogenerator is developed followed by surface functionalization of soybean lecithin(SL) for synergistic enhancement of cancer treatment through photothermal and gas therapy. The resultant GO-Arg-SL nanogenerator not only exhibited good biocompatibility and excellent endocytosis ability, but also exhibited excellent photothermal conversion capability and high sensitivity to release NO within tumor microenvironment via inducible NO synthase(i NOS) catalyzation. Moreover, the produced hyperthermia and intracellular NO could synergistically kill cancer cells both in vitro and in vivo. More importantly, this nanogenerator can efficiently eliminate tumor while inhibiting the tumor recurrence because of the immunogenic cell death(ICD) elicited by NIR laser-triggered hyperthermia and the immune response activation by massive NO generation. We envision that the GO-Arg-SL nanogenerator could provide a potential strategy for synergistic photothermal and gas therapy.

ZrC-ZrB_2-SiC ceramic nanocomposites derived from a novel single-source precursor with high ceramic yield

For the first time, ZrC-ZrB_2-SiC ceramic nanocomposites were successfully prepared by a single-source-precursor route, with allylhydridopolycarbosilane(AHPCS),triethylamine borane(TEAB),and bis(cyclopentadienyl) zirconium dichloride(Cp_2 ZrCl_2) as starting materials. The polymer-to-ceramic transformation and thermal behavior of obtained single-source precursor were characterized by means of Fourier transform infrared spectroscopy(FT-IR) and thermal gravimetric analysis(TGA). The results show that the precursor possesses a high ceramic yield about 85% at 1000 ℃.The phase composition and microstructure of formed ZrC-ZrB_2-SiC ceramics were investigated by means of X-ray diffraction(XRD) and high resolution transmission electron microscopy(HRTEM).Meanwhile, the weight loss and chemical composition of the resultant ZrC-ZrB_2-SiC nanocomposites were investigated after annealing at high temperature up to 1800 ℃. High temperature behavior with respect to decomposition as well as crystallization shows a promising high temperature stability of the formed ZrC-ZrB_2-SiC nanocomposites.

Two Alkali Metal Germanophosphates Na_(3)[Ge(OH)(PO_(4))_(2)]·2H_(2)O and Li_(2)Na[GeO(HPO_(4))(PO_(4))]:Crystal Structures and Thermal Stability

Two new alkali metal germanophosphates,namely,Na_(3)[Ge(OH)(PO_(4))_(2)]·2 H2 O and Li_(2)Na[GeO(HPO_(4))(PO_(4))],have been prepared by solvothermal method,and their crystal structures were determined by single-crystal X-ray diffraction.The title two compounds crystalize in the same orthorhombic space group Pbcm(No.57)and feature similar chain-like structure which is built from zig-zag GeO_(6) octahedral thread loop branched by PO_(4) tetrahedra.For Na_(3)[Ge(OH)(PO_(4))_(2)]·2 H_(2)O,a=10.1650(9),b=13.1975(12),c=6.9751(7)Å,V=935.73(15)Å^(3),Z=4,R=0.0356 and wR=0.1109;and for Li_(2)Na[GeO(HPO_(4))(PO_(4))],a=6.9855(5),b=14.5809(18),c=6.6620(5)Å,V=678.56(11)Å^(3),Z=4,R=0.0286,and w R=0.0762.The partial substitution of Na ions by Li ions not only significantly influences the total structural features and the water molecule contents,but also impacts on their thermal stabilities.Li_(2)Na[GeO(HPO_(4))(PO_(4))]is thermally stable up to 400℃,whereas only 150℃ for Na_(3)[Ge(OH)(PO_(4))_(2)]·2 H2 O.

Ni_(2)M^(Ⅱ)Te^(Ⅳ)_(2)O_(2)(PO_(4))_(2)(OH)_(4)(M^(Ⅱ)=Ni,Zn):Synthesis,Crystal Structure,and Magnetic Properties

Two isostructural tellurite phosphates Ni_(2)M^(Ⅱ)Te^(Ⅳ)_(2)O_(2)(PO_(4))_(2)(OH)_(4)(M^(Ⅱ)=Ni,Zn)have been synthesized via hydrothermal method.Both of them crystalize in monoclinic space group C2/m(No.12).For Ni_(2)ZnTe^(Ⅳ)_(2)O_(2)(PO_(4))_(2)(OH)_(4),a=19.3247(10),b=5.9697(3),c=4.7737(2)Å,β=103.637(5)°,V=535.18(5)Å^(3),Z=2,M_(r)=727.94,S=1.103,D_(c)=4.517 g·cm^(-3),μ(Mo Kα)=11.434 mm^(-1) and F(000)=672,the final R=0.0369and wR=0.1086 for 639 observed reflections with I>2σ(I).The crystal structure of Ni_(2)M^(Ⅱ)Te^(Ⅳ)_(2)O_(2)(PO_(4))_(2)(OH)_(4)(M^(Ⅱ)=Ni,Zn)features a 3D framework composed of[Ni_(2)O_(2)(PO_(4))_(2)]^(6-)layers interconnected by[MTe_(2)O_(2)(OH)_(4)]^(2+)single chains.Different magnetic susceptibility results at low temperature of the two title compounds confirm that Zn(1)completely occupies the Ni(2)position but not partially substitutes both Ni(1)and Ni(2)position atoms.Additionally,the acentric TeO_(3)(OH)_(2) tetragonal pyramids are aligned in an antiparallel manner,resulting in the crystallization of centrosymmetric(C2/m)crystal structure instead of the non-centrosymmetric crystal structure.The investigation of the origin of centrosymmetric crystal structure with strong dipole moment units provides deeper understanding for future rational design for non-centrosymmetric crystal structure.