Researchers Propose Electrodriven Chemical Looping Ammonia Synthesis Mediated by Lithium Imide

Ammo n i a(N H 3)i s a promising energy vector for the storage and utilization of renewable energies.Artificially synthesizing NH3 from its elements(Haber-Bosch process)requires harsh reaction conditions(400-500°C,10-30 MPa)because N2 is inert and nonpolar with a strong N≡N bond.The synthesis of NH3 under mild conditions is still challenging.

A wideband low-phase-noise LC VCO for DRM/DAB frequency synthesizer

The wideband CMOS voltage-controlled oscillator（VCO）with low phase noise and low power consumption is presented for a DRM/DAB（digital radio mondiale and digital audio broadcasting）frequency synthesizer.In order to obtain a wide band and a large tuning range,a parallel switched capacitor bank is added in the LC tank.The proposed VCO is implemented in SMIC 0.18-μm RF CMOS technology and the chip area is 750 μm×560 μm,including the test buffer circuit and the pads.Measured results show that the tuning range is 44.6%;i.e.,the frequency turning range is from 2.27 to 3.57 GHz.The measured phase noise is-122.22 dBc/Hz at a 1 MHz offset from the carrier.The maximum power consumption of the core part is 6.16 mW at a 1.8 V power supply.

A Novel Method to Compensate the Sigma-Delta Shaped Noise for Wide Band Fractional-N Frequency Synthesizers

A novel method to partially compensate sigma-delta shaped noise is proposed. By injecting the compensation current into the passive loop filter during the delay time of the phase frequency detector（PFD）,a maximum reduction of the phase noise by about 16dB can be achieved. Compared to other compensation methods,the technique proposed here is relatively simple and easy to implement. Key building blocks for realizing the noise cancellation,including the delay variable PFD and compensation current source, are specially designed. Both the behavior level and circuit level simulation results are presented.

Synthesis of Refractory Cordierite from Calcined Bauxite, Talcum and Quartz

A cordierite was synthesized from calcined bauxite, talcum, and quartz. The properties and microstructure of the cordierite sintered samples were characterized by Archimedes＇ method, thermal dilatometry, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and so on. The experimental results showed that calcined bauxite could broaden the range of synthesizing temperature from 1300 ℃ to 1420 ℃ and get pure cordierite. The bulk density and linear thermal expansion coefficient of the sample synthesized at 1420 ℃ for 2 h were 1.97 g·cm^-3 and 2.1×10^-6 ℃^-1, respectively. The XRD analysis showed that the major crystalline phase was a-cordierite with almost no glassy matters, the SEM images illustrated a small vent hole and the size were 5 -100 μm, the well-grown hexagonal and granular cordierite grains had the sizes distributed among 0.1-8 ;xm, and providing high mechanical strength and lower linear thermal expansion coefficient.

Microwave-assisted synthesis of new N^4-[bi-(4-fluorophenyl)-methyl]-piperazine thiosemicarbazones under solvent-free conditions

Six new N4-[bi-（4-fluorophenyl）-methyl]-piperazine thiosemicarbazones 3a-f have been prepared starting from [bi-（4-fluorophenyl）-methyl]-piperazine in solvent-free condition under microwave irradiation with excellent yields. Their structures have been determined by elemental analysis, IR, MS and 1H NMR data.

Synthesis of C_3S by Sol-Gel Technique and Its Features

Sol-gel method is a technique to synthesize inorganic materials based on wet-chemical reaction theory. The results have shown that reactants tetraethyl orthosilicate （TEOS） and Ca（NO3）2·4H2O can form sol and gel in solution at 50-60 ℃, and the cosolvents are propyl alcohol （NPA） and H2O, the catalyst is HNO3. This sol-gel is burned for 12 hat 1 350-1 450 ℃ so that the organic matter, free water （moisture） in sol-gel system are removed and a solid reaction has taken place to form the resulting product. The product has been confirmed to be C3S by XRD, SEM and 29Si MAS NMR, as well as free lime content of the product which is less than 0.2% was determined by propanetriol-ethanol-method. The analysis determined by EDXA has indicated that the n（Ca）/n（Si） ratio in corresponding to micro-region is close to theoretical value of 3∶1. This resulting product is C3S with Si sites of Q0 polymerization, and has higher purity and hydraulic activities at earlier age of hydration.

Hydrothermal Synthesis, Crystal Structure,Thermal Stability and Photophysical Property of a Novel Zinc Complex with Mixed Ligands

A novel metal-organic coordination complex [Zn（CHIP）（AIC）]n （1, CHIP = 2-（4- chlorophenyl）-lH-imidazo[4,5-f][1,10]phenanthroline, A1C = 5-amino-isophthalic acid） has been synthesized by hydrothermal reactions and characterized by elemental analysis, thermogravimetric （TG） analysis, infrared spectrum （IR） and single-crystal X-ray diffraction. Complex 1 crystallizes in monoclinic, space group C2/c with a = 18.259（5）, b = 17.191（4）, c = 16.371（4） A, V= 4717（2） A3, C27H16C1NsOnZn, Mr= 575.29, Dc = 1.620 g/cm3, p（MoKa） = 1.202 mm-1, F（000） = 2335, Z = 8, the final R = 0.032 and wR = 0.074 for 4723 observed reflections （I 〉 2σ（I））. Single-crystal X-ray diffraction reveals that 1 exhibits one-dimensional （1D） double chains, which are linked by H-bond intersections into a 2D structure. TG analysis shows clear weight loss due to the decomposition of different ligands. The luminescent properties for the ligand and complex 1 were also studied.

Hydrothermal Synthesis,Crystal Structure and Magnetic Property of a New Co(Ⅱ) Complex:[Co(4,4'-bpy)_2(H_2O)_2(4-FBA)_2]·(4,4'-bpy)

A new complex [Co（4,4＇-bpy）2（H2O）2（4-FBA）2]·（4,4＇-bpy）（1） has been hydro-thermally synthesized using cobalt,4,4＇-bipyridyl（4,4＇-bpy） and 4-fluorobenzoic acid（4-HFBA）,and characterized by thermal analysis,single-crystal X-ray diffraction and magnetic property.The complex crystallizes in the triclinic system,space group P,Z = 1.Crystal data：C54H44CoF2N8O6,Mr = 997.90,a = 9.134（2）,b = 11.555（2）,c = 12.867（3） ,α = 66.02（3）,β = 77.96（3）,= 73.11（3）°,V = 1180.9（4） 3,Dc = 1.403 g/cm3,μ（MoKα） = 0.433 mm-1,F（000） = 517,the final R = 0.0633 and wR = 0.1171 for 2152 observed reflections（I 〉 2σ（I））.The title complex is assembled into 1D supramolecular chains parallel to [001] based on the adjacent molecular ··· stacking interactions and hydrogen bonds.The variable temperature magnetic measurements show a weak ferromagnetic behavior over 300-160 K followed by antiferromagnetic behavior below 160 K for the title complex.

Present Synthesizing Situation and Application Mechanism of Hercynite in Cement Kilns

The magnesia -hercynite bricks offer a new lining to rotary cement kiln. They are well adopted and widely used in the high temperature zone of cement kiln, and have obtained good performance at rigorous and severe working conditions. The synthesis of hercynite requires a suitable atmosphere with proper O2 partial pressures which makes sure FeO can stably exist at the synthesizing temperature. Current industrial production of hercynite mainly adopts fused method. The other method, sinte- ring method, is not mature and needs further research. The magnesia - hercynite brick shows high hot toughhess, high adhesion strength to kiln crust, and good corrosion resistance to alkali salt in cement kilns. The mismatching of thermal expansion between magnesia and hercynite can improve the thermal shock resistance of the bricks, but the oxidation of partial Fe^2＋ , the high temperature solution, and low temperature exsolution of transgranular secondary spinel lead to cubical expansion, .formation of more cracks, and poor thermal shock resistance of the bricks.

Reductive Cleavage of S-S Bond by Samarium Diiodide: Synthesis of β-Thioesters and β-Thionitriles

The reduction of disulfides by samarium diiodide led to sa arium thiolates (ArSSml2).This new thiolate anion species reacted smoothly with α, β -unsaturated esters (nitriles) to give 1,4-addition products β -thioesters and β -thionitriles in good yields under mild and neutralcondition.

Synthesis, Crystal Structure and Characterization of the Host-guest Type UOF

A new uranium（Ⅵ）-polycarboxylate framework with honeycomb（6,3） nets {[Zn（phen）_2（H_2O）_2][（UO_2）_2（BDC）_3]·2H_2O}n（1, BDC = benzene-1,4-dicarboxylate） was hydrotherrmally synthesized by the reactions of Zn（NO_3）_2·6H_2O with phenanthroine, UO_2（NO_3）_2·6H_2O and benzene-1,4-dicarboxylate. The complex was structurally characterized by FT-IR spectroscopy, powder XRD and X-ray single-crystal diffraction. Crystal data for 1： monoclinic, space group Cc with M_r = 1522.19, a = 14.9385（10）, b = 20.4922（13）, c = 15.9728（10） ？, β = 100.1240（10）°, V = 4813.5（5） ？~3, Z = 4, D_c = 2.100 g？cm^（–3）, μ = 7.293 mm^（–1）, F（000） = 2872, the final R = 0.0224 and w R= 0.0677 for 6522 observed reflections with I 〉 2σ（I）. Hydrogen bonds and π-π stacking interactions contribute to the structural extension and stabilization. Experimental band gap of about 3.57 e V indicates its broad gap semiconductor nature. UV-Vis spectra and solid-state luminescence were discussed in detail. The compound exhibits photocatalytic activities for the degradation of rhodamine B.

Mannich Base Derivatives of 1,2-Benzisothiazolin-3-one: Syntheses, Crystal Structures and Bioactivities

Twelve Mannich base derivatives of 1,2-benzisothiazolin-3-one were synthesized by the reaction of 1,2-benzisothiazol-3（2H）-one （BIT） with different amines and formaldehyde. All the compounds were characterized by elemental analysis, IR spectroscopy, MS and 1H NMR. The crystal structure for 2,2＇-methylenebis（benzo[d]isothiazol-3（2H）-one） （3） has been determined by X-ray single-crystal structure analysis. Compound 3 （C15HIoN202S2） crystallizes in the monoclinic system, space group C2/c with a = 25.052（8）, b = 4.510（1）, c = 11.948（4） A, β = 100.992（4）°, V= 1325.2（7） A3, Mr = 314.37, Dc = 1.576 Mg.m-3, p = 0.25 mm-1, F（000） = 648, Z = 4, R = 0.034 and wR = 0.087. The preliminary biological test indicated that the compounds （2b, 2c） showed growth inhibitory activity against the gram-positive and gram-negative bacteria.

Synthesis and Crystal Structure of (E)-ethyl 6-benzyl-2-[(cyclopropylmethylamino)(4-fluorophenylamino)-methyleneamino]-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate ethanol monosolvate

The crystal structure of the new title compound （E）-ethyl 6-benzyl-2-[（cyclopropylmethylamino）（4-fluorophenylamino）methyleneamino]-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate ethanol monosolvate （C28H31FN 4O2S·C2H6O, Mr=552.70） has been prepared and determined by single-crystal X-ray diffraction. The crystal is of monoclinic system, space group P21/c with a=13.806（10）, b=10.850（7）, c=19.938（14）, β=98.842（9）° , V=2951（4）3 , Z=4, Dc=1.244g/cm 3 , F（000）=1176, μ=0.153 mm-1 , MoKα radiation （λ=0.71073）, R=0.0758 and wR=0.2234 for 4262 observed reflections with I 〉 2σ（I）. Intramolecular N-H…S and C-H…N interactions as well as intermolecular N-H…O and O-H…N hydrogen bonds help to stabilize the crystal structure. X-ray diffraction analysis reveals that the asymmetric unit contains one title molecule and one ethanol molecule.

Low spurious noise frequency synthesis based on a DDS-driven wideband PLL architecture

An S-band frequency synthesizer for a stepped-frequency radar is presented. This frequen- cy synthesizer is based on a direct digital synthesizer （ DDS ） -driven wideband phase-locked loop （PLL） architecture which can achieve low spurious noise and rapid frequency hopping simultaneous- ly. The mechanism of introducing high level spurs by the images of DDS digital to analog convertor （DAC） output is analyzed. A novel DDS frequency planning method is proposed to ensure low col- ored noise within the entire bandwidth. The designed output frequency range is 3. 765 -4. 085 GHz, and the step size is 5 MHz with frequency agility of less than 1 μs. Measured results demonstrate that the average spurious free dynamic range （SFDR） is about 64 dBc in a 320 MHz bandwidth.

Synthesis of Some New Spiro <i>β</i>-Lactams and Thiazolidinones Compounds Containing Sulfur Incorporating Quinon Compounds

A series of spiro, β-Lactams, and thiazolidinones incorporating compounds 4 have been synthesized by cycloaddition reaction of, chloroacetyl chloride and mercaptoacetic acid with the synthesized Shiff,s bases 5a-c to give new spiro β- Lactam 6a-c and spiro thiazolidinone 7a-c the cycloaddition were characterized by spectral data including HNMR, 13C-NMR, IR and elemental analysis.

Asymmetric Synthesis of (3R,5R)-3-((tert-Butyldimethylsily)oxy)-5-((Z)-2-Bromovinyl)-Tetrahydro-Furan-2-one,an Intermediate for the Synthesis of Fostriecin

(3R,5R)-3-((tert-Butyldimethylsily)oxy)-5-((Z)-2-bromovinyl)-tetrahydro-furan-2-one, an intermediate for the synthesis of Fostriecin was achieved by intramolecular asymmetric induction in propene addition of (-)-8-phenylmenthyl glyoxylate followed by inversion of C3-hydroxyl group and Sharpless asymmetric dihydroxylation with simultaneous cyclization to give lactone 5. Then protection of C3-hydroxyl group and oxidation of the C6-primary hydroxyl group which reacted with Wittig reagent to yield the target compound 4.

Synthesis and Crystal Structure of N-Benzyl-1-ferrocenyl Benzalimine

The title compound N-benzyl-1-ferrocenyl benzalimine, C24H21FeN, has been syn- thesized by a new method with molecular sieves (4 ? as catalyst, and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21/c with a = 8.2298(16), b = 11.675(2), c = 19.556(4) ? b = 91.20(3)o, V = 1878.6(6) 3, Z = 4, Mr = 379.27, Dc = 1.341g/cm3, F(000) = 792, m = 0.809 mm-1, the final R = 0.0363 and wR = 0.0765 for 2809 observed reflections (I > 2s(I)). In the title compound, the Fe(1) atom is almost located at the center of the two cyclopentadienyl rings, with the Fe(1)Cp(1) and Fe(1)Cp(2) distances of 1.644(9) and 1.649(8) ? respectively. The two cyclopentadienyl rings are nearly parallel, and the dihedral angle between the ?5(C5H4) and ?5(C5H5) rings is 0.97(12)o. The C(11)=N unit is conjugated with the ?5(C5H4) ring which forms a dihedral angle of 101.3(2)o with the adjacent phenyl ring.

Audio Video Compression Stream Synthesis and Implementation

Multiplex of digital streams is one of the key technologies in audio-video communication, and determines audio-video quality. A design scheme for an MPEG2 compliant digital television system including audio-video encoding and multiplexing was implemented. The principles and elements of system layer stream synthesis were analyzed. The key technologies of video and audio PES packetization were discussed, such as stream structure, scheduling matching, audio-video synchronization, data flow and buffering. DSP and FPGA are combined to construct header information and packet structure. The substitution of traditional RAM or PLD results in high operational efficiency and saves memory space. A scheduling algorithm was introduced for PES coding, using the monitor information of PES buffers. DTS is generated by multiplexer to guarantee synchronization. The system is not only simple but also stable, and maintains synchronization constraints of the standard. It supports both analogy and digital audio-video source input, and provides real-time MPEG2 compliant TS/PS output. It has perfect performance and meets the national broadcasting requirements.

Synthesis of Cordierite from Rectorite-Talc-Alumina without Additives

Rectorite,Talc and alumina were used to obtain high-quality cordierite with stoichiometric composition (51.3 wt% SiO_2,34.9 wt% Al_2O_3,13.8 wt% Al_2O_3).The water absorption,apparent porosity,bulk density,thermal expansion coefficient,crystalline phases and microstructure were tested by means of X-ray diffractometer(XRD),scanning electronic microscopy(SEM),Archimedes immersion technique,etc.This work systematically studied the synthesizing process of the cordierite.The result shows that the cordierite can be synthesized at a lower temperature and within a wider temperature range by using the rectorite as clay raw materials.

Synthesis and Crystal Structure of E,E-1,4-Bis[4'-(N,N-di-n-butylamino)- styryl]-2,5-dimenthoxybenzene

The title compound E,E-1,4-bis[4?-(N,N-di-n-butylamino)styryl]-2,5-dimen- thoxybenzene (abbreviated to DBMB) has been synthesized by the wittig reaction of [(2,5- dimethoxy-1,4-phenylene)]bis(methylene)]bistriphenylphosphonium dichloride with 4-(N,N-di-n- butylamino)benzaldehyde. Its crystal structure was determined by a four-circle diffractometer. Crystal data: C40H56N2O2, Mr = 596.87, triclinic, space group P1, a = 0.9303(2), b = 0.9625(2), c = 1.0442(2) nm, α = 81.493(12), β = 78.387(12), γ = 87.876(11)o, V = 0.9057(4) nm3, Z = 1, Dc = 1.094 g/cm3, F(000) = 326, μ(MoKa) = 0.066 mm-1, the final R = 0.0925 and wR = 0.2092. The results reveal that the molecule is a completely reverse structure with fine symmetry and a conju- gated system.