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Novel chiral cobalt complexes containing a PNNP-type ligand were synthesized using a straightforward method. The structures of the cobalt complexes have been fully characterized by X-ray crystallography, high resolution mass spectrometry (HRMS), and electron paramagnetic resonance (EPR). Using H2 as the hydrogen source, the cobalt-catalyzed asymmetric hydrogenation of various ketones was investigated, and the corresponding chiral alcohols were afforded with up to 99 % yield and 95 % ee. To the best of our knowledge, this is the first example of a cobalt-catalyzed enantioselective hydrogenation of ketones with molecular hydrogen.

Novel nickel(II) complexes 1 and 2 could be conveniently prepared using PxNy-type ligands and easily available NiCl2·6H2O as a starting material. Furthermore, we obtained the single crystals suitable for X-ray diffraction to confirm the structure of these two nickel(II) complexes. With the well-designed nickel(II) complex, the hydrogenation of a wide range of ketones proceeded smoothly under relative mild reaction conditions, affording the corresponding alcohols with high isolated yields.

With the improvement of computer hardware and software performance, digital multimedia technology has been applied to various fields. The visual effect of ceramic art image is affected mainly by the brightness, texture and color, in which the image defects will affect the visual effect of the ceramic product. This paper designs the digital processing system of a new ceramic art image processing, the system can repair defects in ceramic art image. In order to verify the validity and reliability of digital processing system, the lead-free perovskite structure BZT based ceramics is prepared in this paper, and the use of electron microscope and digital camera take the ceramic products processing image with artistic defects, and then using VB programming digital image processing technology carries out color re coating for the ceramic, the ceramic products electron microscopy images after restoration will be obtained by the image boundary restructuring, which provides a new computer method for the processing art of the ceramic products.

Undeformed chip thickness is one of the most important parameters in grinding process, which is related to the entire abrasive grains in grinding simultaneously and changed periodically with time. Simplifying the geometric shape of abrasive grains ,the paper modifies the mathematic models of undeformed chip thickness by analytic method, establishes an universal calculation model of grinding force based on undeformed chip thickness, then optimizes the parameters of the model by restrictive random direction method according to the measuring experiments of the inter-grain spacing about CBN electroplated wheels and the grinding experiments of steel 55 during surface grinding, analyses the influence factors of the friction ratio on the grinding force. The results show that under the same grinding depth， both of the ratio and the grinding force will be decreased with the increase of velocity ratio VS/VW, but the ratio increases and the grinding force decreases with the increase of inter-grain spacing.

A new grinding method that outer race elliptic track in ball basket constant velocity joint is ground by means of basin-like grinding wheel is proposed herein. Aiming at the grinding process with basin-like grinding wheel, the paper establishes the mathematical model, optimizes the parameters by using restrictive random direction method, studies the processing principle in detail, and analyzes the machining errors. The simulation results indicate that the theoretical error of elliptical groove ground by basin-like wheel will be reduced to the level of 0.001 mm. Then, the grinding experiments of elliptical grooves with the basin-like grinding wheel were completed, and the measurements of the grooves by portable arm coordinate measuring machine were carried out, which validates the feasibility of this grinding technology.

Crystal structures of three fluorides (NH 4 ) 2 NaFeF 6 , ( Fe ), (NH 4 ) 2 NaGaF 6 , ( Ga ), and (NH 4 ) 2 NaCrF 6 , ( Cr ), as well as a substituted compound [(NH 4 ) 1− x K x ] 2 KAlF 6 ( x ≈0.17), ( Al ), have been refined using single-crystal and powder X-ray diffraction techniques. All these four ammonium hexafluorides have a cubic elpasolite-type structure and crystallize in the space group Fm 3¯ m with lattice constants a =8.483(3), 8.450 (3), 8.4472(2) and 8.724(3) A for compounds ( Fe) , ( Ga), (Cr) and (Al) , respectively. The effective ionic radius of the ammonium ion calculated from those compounds has a mean value of R =1.729 A for CN=12. An ultraviolet–visible absorption spectrum of (NH 4 ) 2 NaCrF 6 , measured at room temperature, gives a crystal field (Dq=1575 cm −1 ) and Racah parameters ( B =758 cm −1 and C =3374 cm −1 ). Abnormal anisotropic thermal parameters of fluorine atoms have been observed in the compound (Al) , and interpreted to arise from four strong hydrogen bonds (F…H–N) that are distributed in a square form around each fluorine atom.

To improve the machining efficiency of large symmetrical freeform surface, this paper proposes a new machining method: symmetrical machining (SM). Based on the concept of collision avoidance plane (CAP), collisions among cutters or headstocks are avoided, and the area of machining residue is controlled effectively. Machining residue is eliminated due to proper design of symmetrical tool in mechanism and control project. Taking 5-axis symmetrical machine with columnar headstocks and flat cutters as example, this paper proposes collision avoidance algorithm. Finally, using a twin-skeg ship model surface as an example, the method is applied to avoiding collisions in original tool path. Simulation and real machining results show that the scheme is practical. Furthermore, the machining efficiency of SM is improved 85% more than that of the traditional single cutter technology.

A series of N,N′-bis(substituted-benzamido)thioureas (3a–e, substituent = p-OEt, p-Me, H, p-Cl, and m-Cl) was designed as anion receptors based on their double hydrogen bonding interaction with anions. NMR and X-ray crystal structural analyses revealed that in these receptor molecules the benzamido moiety serving as a spectral signal reporter and the thiourea moiety as anion binding site were decoupled by the twisted N–N single bond and the two thioureido and amido NH protons experienced differed electronic environment. Yet the absorption spectra of 3a–e in acetonitrile in the presence of anions such as AcO−, F−, and H2PO4− underwent substantial changes by the appearance of a new band at ca. 325 nm, which is red-shifted by ca. 60 nm, and of a clear isosbestic point at 270 nm, suggesting that anion binding led to the communication between thiourea binding site and benzamido signal reporter via probably a conformational change around the N–N bond. The new band energies were found correlating linearly with the Hammett constant of the substituent with a slope of −0.361 eV, indicative of the charge-transfer character of the absorption band. The binding constants for AcO− and F− of 3a–e were obtained at not less than 107 M−1 orders of magnitude, which are much higher than those of the corresponding N,N′-bisarylthioureas. We suggest that anion binding to the thiourea moiety in 3a–e switches on charge transfer in the anion-receptor binding complex, which reinforces anion binding and therefore results in a dramatically enhanced binding affinity of the receptors. The symmetric N,N′-bis(benzamido)thioureas were therefore found better in anion binding and sensing than N-benzamidothioureas.

The first lutetium diphosphate NH4LuP2O7 has been prepared by a two-step, low-temperature self-flux synthesis in the presence of the F– anion, functioning as a mineralizer, which played a significant role in the synthetic process. The crystal structure has been characterized by single-crystal X-ray diffraction. The title compound crystallizes in a monoclinic system of the space group P21/c (No. 14), a = 7.651(2) A, b = 10.789(2) A, c = 8.577(2) A, β = 105.75(3)°, V = 681.4(2) A3, Z = 4. The three-dimensional framework of NH4LuP2O7, composed of Lu2P4O14 building units formed by vertex-linking LuO6 and P2O7 goups, is isostructural with compounds of the type KAlP2O7 in the ternary diphosphate(AIMIIIP2O7) system. X-ray-excited luminescence measurements of Ce-activated samples show insteresting scintillation properties with a short decay time of 16 ns at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

To determine workspace and relationship between the workspace and geometry of parallel manipulator is important for optimum design of parallel manipulators. In this paper, the workspace and the relationship between the workspace and the geometry of 3-UPU parallel manipulators with pure translation are investigated. Geometric and non-geometric constraints are denned and taken account of in determining the workspace of the translation 3-UPU manipulators. A direct average condition number is used as the global performance index of the workspace. This research shows that there exists an optimal value of the direct average condition number favorable for a good design of parallel mechanisms. The results presented in this paper are useful for the optimum design of 3-UPU parallel manipulators.

Three novel metal-cluster based coordination polymers (MCCPs) with formulae [Zn4(μ3-OH)2(H2O)2(sip)2(4,4′-bpy)2]·3H2O (MCCP-4), [Cd4(μ3-OH)2(H2O)2(sip)2(4,4′-bpy)4]·H2O (MCCP-5) and [Cd6(μ3-OH)4(μ2-OH2)2(OH2)2 (nip)4(4,4′-bpy)3]·3H2O (MCCP-6) [H2sip = 5-sulfoisophthalic acid, H2nip = 5-nitroisophthalic acid and 4,4′-bpy = 4,4′-bipyridyl] were hydrothermally synthesized and characterized by single-crystal X-ray diffraction studies. MCCP-4 crystallizes in the triclinic space group P with a = 10.106(2), b = 10.851(2), c = 11.125(2) A, α = 105.66(3), β = 112.63(3), γ = 98.18(3)°, V = 1041.8(4) A3, and Z = 2. MCCP-5 crystallizes in the monoclinic space group C2/c with a = 25.602(1), b = 16.571(1), c = 13.322(1) A, β = 92.524(1)°, V = 5646.4(2) A3, and Z = 4. MCCP-4 and -5 consist of similar [M4(μ3-OH)2]6+ tetranuclear building units that are joined through sip and 4,4′-bpy ligands to generate a two-dimensional structure (MCCP-4) and a three-dimensional structure (MCCP-5), respectively. MCCP-6 crystallizes in the triclinic space group P with a = 14.295(2), b = 14.472(2), c = 20.204(3) A, α = 73.362(3), β = 82.200(3), γ = 62.769(2)°, V = 3560.9(10) A3, and Z = 2. MCCP-6 contains unprecedented [Cd6(μ3-OH)4(μ2-OH2)2]8+ hexanuclear building units which are linked through nip and 4,4′-bpy ligands to afford a two-dimensional structure. The infrared spectroscopy, thermal stability and photoluminescence of the three complexes were studied. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

A fractal scanning path which is a FASS (space-filling, self-avoiding, simple and self-similar) curve is proposed for selective laser sintering (SLS). The authors’ preliminary research has proved that the samples which are produced by SLS along a fractal scanning path possess improved physical performance. However, the complete FASS fractal curves can only fill a square region, thus a method is developed to realize trimming of the fractal curves suitable for arbitrary boundaries by means of judging intersection points between arbitrary boundaries and the fractal curves as well as to keep the FASS feature. Moreover, a two-lever special control system is built to realize the real-time sintering of samples aiming at the fractal scanning, and the interrupt technology is used for the main-accessory system synchronization.

The fractal curve is proposed as a novel scanning-path used in Layered Manufacturing. Aiming at a limitation that the fractal curve can only fill a square region, a method is developed to realize the trimming of fractal curve in arbitrary boundary layer by means of judging intersection points between parameterized arbitrary boundary and a FASS (space-filling, self-avoiding, simple and self-similar) fractal curve. Accordingly, the related algorithm concerning with determining intersection points has been investigated according to the recursion feature of the fractal curve, and in the process of the fractal curve traversed, the rule of judging intersection points is ascertained as well, so that the laser-scanning beam can “walk” along the fractal curve inside the desired boundary, and arbitrary contour components are fabricated.

BHInKO9P2, triclinic, P1 (No. 2), a = 5.2638(4) A, b = 8.4791(5) A, c = 8.1469(9) A, = 91.741(7)°, = 93.061(7)°, = 79.823(5)°, V = 357.3 A, Z = 2, Rgt(F) = 0.052, wRref(F) = 0.113, T = 293 K. Source of material KIn[BP2O8(OH)] was synthesized under mild hydrothermal conditions. The reactions were carried out with mixtures of In metal (0.057 g) dissolved in 1 ml of HCl (18%), H3BO3 (0.062 g) and K2HPO4 (0.522 g) (molar ratio of In:P:B = 1:2:3) in aqueous solution. The mixtures were sealed in glass tubes (after adding 1 ml H2O to achieve a degree of filling of 30%) with subsequent heating at 418 K for 14 days. The starting materials were all of analytical purity grade. Discussion With the increasing interest in microporous materials, the syntheses of compounds like borophosphates with open framework structures have drawn much attention during the past few years and show a rich crystal chemistry [1]. Systems including a p-block metal have not been widely explored up to now besides two compounds with Al and Ga [2,3] reported only recently and two phases with In in the present issue [4,5]. The structure of the title compound is isotypic to the K-Fe [6] and ammonium-In analogues [5]. The structure is characterized by isolated InO5(OH) octahedra sharing common O-corners with phosphate and common O(OH)-corner with hydrogenborate groups from the trinuclear oligomeric units [B2P4O16(OH)2]. The condensation of the borophosphate oligomers with In-coordination octahedra via common corners results in a three-dimensional framework which contains elliptical channels running along the a axis. The cross section of the channels is defined by eight-membered octahedral/tetrahedral rings (two In coordination octahedra, four phosphateand two borate-groups). Potassium ions are distributed within the open channels. The In—O and In—OH bond distances range from 2.110 A to 2.179 A. Both the oligomeric borophosphate and the coordination octahedron of In are similar to its K-Feand NH4-In-analogues [5,6] by considering the bond distances In—O, P—O and B—O and bond angles. Z. Kristallogr. NCS 217 (2002) 3–4 3 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colorless prism, size 0.2 × 0.25 × 0.3 mm Wavelength: Mo K radiation (0.71073 A) : 44.09 cm Diffractometer, scan mode: Enraf Nonius CAD4, /2 2 max: 68.04° N(hkl)measured, N(hkl)unique: 3081, 2910 Criterion for Iobs, N(hkl)gt: Iobs > 2 (Iobs), 2126 N(param)refined: 131 Program: SHELXL-97 [7] Table 1. Data collection and handling. H(1) 2i 0.68(2) 0.51(1) 0.64(1) 0.05 Table 2. Atomic coordinates and displacement parameters (in A). Atom Site x y z Uiso

An ammonium indium hydrogen phosphate, NH 4 In(OH)PO 4 , was synthesized under mild hydrothermal conditions, and the crystal structure was characterized by single-crystal X-ray diffraction method. The compound crystallizes with the RbIn(OH)PO 4 type with the following data: M r =244.84, tetragonal, tP 104, P 4 3 2 1 2 (No.96), a =9.416(2) A, c =11.159(3) A, V =989.9(3) A 3 , Z =8, D x =3.288 g cm −3 , λ =0.71073 A, μ =50.34 cm −1 , F (000)=928, T =293 K, R 1=0.0606, wR 2=0.1472 for 91 variables and 1813 contributing unique reflections. The structure is characterized by chiral InO 4 (OH) 2 chains along the c axis formed by sharing OH corners. The chains are isolated by PO 4 tetrahedra leading to a three-dimensional framework structure with channels occupied by NH 4 + ions. The framework structure is similar to that of KIn(OH)PO 4 and γ -NaTiOPO 4 . The hydrogen bonds formed by NH 4 + with the polyhedral oxygen atoms play an important role in the anisotropic changes of the lattice with respect to its alkali metal analogues. The topological construction of the title structure can be considered as an augmented 4,6-net with larger porosity.

A sodium cobalt hydrogen phosphate hydrate, Na 4 Co 3 H 2 (PO 4 ) 4 ·8H 2 O, was synthesized by the mild hydrothermal method, and the crystal structure was characterized by the single-crystal X-ray diffraction method. The layered structure possesses a new type with the following data: Mr=794.775, monoclinic, mP 106, P 2 1 / c – e 26 d (No. 14), a =7.3547(9) A, b =9.222(1) A, c =15.186(2) A, β =95.18(1)°, V =1025.9(3) A 3 , Z =2, Dx =2.573 g cm −3 , λ =0.71073 A, μ =29.0 cm −1 , F (000)=790, T =293 K, R =0.0346, w R =0.0432 for 198 variables and 2278 contributing unique reflections. The structure is characterized by corner- and edge-sharing deformed CoO 5 trigonal bipyramids with PO 4 tetrahedra forming an infinite ribbon along the [010] direction. The ribbons are connected by bridging CoO 6 octahedra resulting in a novel three-cobalt polymeric coordination unit and a polyhedral sheet. The same sheets are packed along the c -axis by sandwiching Na + cations and hydrogen-bonded water molecules to construct the whole structure. The temperature dependence of the magnetic susceptibility of the compound follows the Curie–Weiss law, and the effective magnetic moment of 4.69 μ B corresponds to high-spin Co 2+ ion, confirmed by bond valence sum calculations.

Diammonium sodium hexa­fluoro­aluminate, (NH4)2NaAlF6, obtained by hydro­thermal synthesis, comprises [AlF6]3− octa­hedra forming a face-centred cubic (fcc) arrangement, with Na+ cations filling all octa­hedral inter­stices and NH4+ cations filling all tetra­hedral inter­stices.

The crystal structure of dipotassium iron(III) {hydrogen bis­[hydrogenphosphate(V)]} difluoride, K2Fe[H(HPO4)2]F2, obtained by hydro­thermal synthesis, was determined from single-crystal X-ray diffraction data. The structure is characterized by K+ cations and hydrogen-bonded {[Fe[H(HPO4)2]F2]2−}n chains, which consist of centrosymmetric Fe[F2O4] octa­hedra linked to their four neighbouring phosphate tetra­hedra via common O corners, developing a three-dimensional structure.

The title compound, C13H17NO4, has been obtained as an unexpected product when attempting to prepare diethyl (S)-2-(2-methoxy­carbonyl­amino-3-phenyl­propionyl)­malonate. The crystal structure involves intermolecular N—H⋯O hydrogen bonds.

In Chinese medicine, Xiexin decoction (XXD) has been used for the clinical treatment of diabetes for at least 1700 years. The present study was conducted to investigate the effective ingredients of XXD and their molecular mechanisms of antidiabetic nephropathy in rats. Rats with diabetes induced by high-fat diet and streptozotocin were treated with XXD extract for 12 weeks. XXD significantly improved the glucolipid metabolism disorder, attenuated albuminuria and renal pathological changes, reduced renal advanced glycation end-products, inhibited receptor for advanced glycation end-product and inflammation factors expression, suppressed renal nuclear factor- κ B pathway activity, and downregulated renal transforming growth factor- β 1. The concentrations of multiple components in plasma from XXD were determined by liquid chromatography and tandem mass spectrometry. Pharmacokinetic/pharmacodynamic analysis using partial least square regression revealed that 8 ingredients of XXD were responsible for renal protective effects via actions on multiple molecular targets. Our study suggests that the renal protective role of XXD with multiple effective ingredients involves inhibition of inflammation through downregulation of the nuclear factor- κ B pathway, reducing renal advanced glycation end-products and receptor for advanced glycation end-product in diabetic rats.

The increasing integration of sensors and wireless communication devices into highly mobile platforms such as automobiles makes vehicular sensing networks one of the most promising platforms for many applications. The performance of applications such as traffic reporting, environmental monitoring and distributed surveillance can be improved by using the new techniques developed in vehicular sensing networks. Several distinct features such as highly mobile and predictable movement patterns make vehicular sensing networks different from general computer networks. Therefore, unique solutions for vehicular sensing networks are necessary. In this thesis, we show our efforts on three aspects of vehicular sensing networks: efficiency, security and privacy. The efficiency issue is most critical when there is no central infrastructure or when vehicle-to-infrastructure (V2I) communication bandwidth is a precious resource. Keep uploading every piece of sensor data to a remote server is obviously inefficient. Local data aggregation is required to reduce the communication cost and improve the efficiency. However, how and when to perform the aggregation is not trivial. In this work, a GeoCache concept and Boomerang anchoring protocol are proposed to address this issue. Our work in security is focused on building secret keys for both vehicle-to-vehicle (V2V) and the V2I communication modes. Many applications require secure V2V and V2I communications and two sets of secret keys need to be created independently. Based on the special characteristics existing in vehicular sensing networks, we develop two key agreement algorithms to achieve the target. In many of the applications developed within vehicular sensing networks, GPS data has to be submitted to the central server continuously, which results in serious privacy violation. We have three contributions under the privacy domain. First, we develop a privacy preserving algorithm which protects user privacy without filtering too many location traces. Second, we study the possible privacy leakage due to the detailed location information available. At last, we extend the privacy system design under the assumption that there is no location proxy server and the information available is limited.

In the crystal structure of the title compound, [O(CH2CH2)2NH2][C6H7O7]·H2O, the cation interacts with the negatively charged carboxyl­ato group of adjacent anions [N⋯O 2.847 (3) and 2.942 (3) A], forming a linear chain running along the b axis of the crystal. Adjacent chains are linked through the carboxyl­ic —CO2H groups and the water mol­ecule into a layer structure.

Crystal structures of three fluorides (NH 4 ) 2 NaFeF 6 , ( Fe ), (NH 4 ) 2 NaGaF 6 , ( Ga ), and (NH 4 ) 2 NaCrF 6 , ( Cr ), as well as a substituted compound [(NH 4 ) 1− x K x ] 2 KAlF 6 ( x ≈0.17), ( Al ), have been refined using single-crystal and powder X-ray diffraction techniques. All these four ammonium hexafluorides have a cubic elpasolite-type structure and crystallize in the space group Fm 3¯ m with lattice constants a =8.483(3), 8.450 (3), 8.4472(2) and 8.724(3) A for compounds ( Fe) , ( Ga), (Cr) and (Al) , respectively. The effective ionic radius of the ammonium ion calculated from those compounds has a mean value of R =1.729 A for CN=12. An ultraviolet–visible absorption spectrum of (NH 4 ) 2 NaCrF 6 , measured at room temperature, gives a crystal field (Dq=1575 cm −1 ) and Racah parameters ( B =758 cm −1 and C =3374 cm −1 ). Abnormal anisotropic thermal parameters of fluorine atoms have been observed in the compound (Al) , and interpreted to arise from four strong hydrogen bonds (F…H–N) that are distributed in a square form around each fluorine atom.

The first lutetium diphosphate NH4LuP2O7 has been prepared by a two-step, low-temperature self-flux synthesis in the presence of the F– anion, functioning as a mineralizer, which played a significant role in the synthetic process. The crystal structure has been characterized by single-crystal X-ray diffraction. The title compound crystallizes in a monoclinic system of the space group P21/c (No. 14), a = 7.651(2) A, b = 10.789(2) A, c = 8.577(2) A, β = 105.75(3)°, V = 681.4(2) A3, Z = 4. The three-dimensional framework of NH4LuP2O7, composed of Lu2P4O14 building units formed by vertex-linking LuO6 and P2O7 goups, is isostructural with compounds of the type KAlP2O7 in the ternary diphosphate(AIMIIIP2O7) system. X-ray-excited luminescence measurements of Ce-activated samples show insteresting scintillation properties with a short decay time of 16 ns at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

In the title compound, C17H16O8, inter­molecular O—H⋯O hydrogen bonds link adjacent mol­ecules to form a chain. There are also intra­molecular hydrogen bonds which stabilize the molecular conformation.

In the title compound, C18H17NO4, the carboxylate group is approximately coplanar with the oxazolidine ring, the largest deviation from the least-squares plane being 0.144 (2) A at the nitro­gen atom. The two benzyl rings are located on the same side of this plane, and make dihedral angles with it of 75.23 (4) and 56.97 (7)°.

The title compound, C9H13O4P, has been obtained by the reaction of dimethyl phosphite and benzaldehyde. In the crystal structure, intermolecular O—H...O hydrogen bonds link the molecules into infinite chains.

The title compound, C29H35NO3, was obtained as a major product by reduction of (S)-tert-butyl 4-dibenzyl­amino-3-oxo-5-phenyl­penta­noate. The mol­ecular packing in the crystal structure is stabilized by weak inter­molecular inter­actions and van der Waals forces.

The title compound, C11H17NO2, was obtained by hydrogeno­lysis of (3S,4S)-4-(dibenzyl­amino)-5-phenyl­pentane-1,3-diol. In the crystal structure, inter­molecular O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds link the mol­ecules into a sheet parallel to the ab plane.

The Cu atom in the title compound, [Cu(C7H6NO2S)2(H2O)2(NH3)2], lies on a special position at a crystallographic inversion centre and has a tetragonally distorted octahedral coordination involving the N atoms of two ammine ligands [Cu—N = 2.010 (2) A], the N atoms of two pyridyl­thio­acetate ligands [Cu—N = 2.033 (2) A] and the O atoms of two water mol­ecules [Cu—O = 2.472 (2) A].

The structure of the title compound, an­hydro­fulvic acid, C14H10O7, a yellow acidic metabolite isolated from Paecilomyces sp. was determined by X-ray analysis. The chromone ring system is essentially planar, with the carboxyl­ic acid group coplanar with the ring.

Based on the finite element method the deformation of the joint of linked ball screws is analyzed in detail Meanwhile the calculation results are testified with the strain gauging method. The conclusions of this paper are important to design and manufacture of the joint structure of linked ball screws.

BGaH3NaO10P2, monoclinic, C12/c1 (No. 15), a = 10.408(3) A, b = 8.094(2) A, c = 9.099(2) A, = 116.64(2)°, V = 685.2 A, Z = 4, Rgt(F) = 0.025, wRref(F ) = 0.068, T = 293 K. Source of material NaGa[BP2O7(OH)3] was synthesized under mild hydrothermal conditions. The reaction was carried out with mixtures of Ga metal (0.139 g) dissolved in 1ml of HCl (18%) with Na2HPO4·12H2O (1.075 g) and Na2B4O7·10H2O (0.4767 g) (molar ratio of Ga:P:B = 2:3:6) in aqueous solution. The mixture was sealed in glass tubes (after adding 1 ml H2O to achieve a degree of filling of 30%) with subsequent heating at 408 K for 60 days. The starting materials are all of analytical grade. Discussion With the increasing interest in microporous materials, synthesis of compounds like borophosphates with open framework structure have drawn much attention during the past few years and show a rich crystal chemistry [1]. Systems including a p-block metal have not been widely explored up to now besides one Al compound [2] reported only recently. The structure of the title compound is isotypic to the Fe [3] and Al analogues [2] and is characterized by isolated GaO4(OH)2 octahedra sharing common O-corners with phosphate and common O(OH)-corners with hydrogenborate groups from the ol igomeric uni ts [B2P2O7(OH)3]. The condensation of the borophosphate oligomers with Ga-coordination octahedra via common corners results in an overall three-dimensional framework which contains elliptical channels running along the [001] direction. The cross section of the channels is defined by eight-membered octahedral/tetrahedral rings (four Ga coordination octahedra, two phosphateand two borate-groups). Sodium ions are distributed within the open channels. The Ga—O bond distances are 1.925 and 1.965 A, while the Ga—OH value is increased to 1.995 A. The bond distances P—O and B—O in the oligomeric borophosphate groups correspond to respective values in the Feand Al-analogues [2,3]. Z. Kristallogr. NCS 216 (2001) 15–16 15 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colorless, prism, size 0.15 × 0.2 × 0.3 mm Wavelength: Mo K radiation (0.71073 A) : 45.94 cm Diffractometer, scan mode: Enraf Nonius CAD4, non-profiled scans 2 max: 69.86° N(hkl)measured, N(hkl)unique: 850, 737 Criterion for Iobs, N(hkl)gt: Iobs > 2 (Iobs), 676 N(param)refined: 75 Program: SHELXS-97 [4] Table 1. Data collection and handling. H(1) 4c 1/4 –1/4 1/2 0.05 H(2) 8f 0.485(7) 0.163(6) 0.591(7) 0.05 Table 2. Atomic coordinates and displacement parameters (in A). Atom Site x y z Uiso

The title compound, C6H5BrClN, is almost planar (r.m.s. deviation = 0.018 Å). In the crystal, molecules are linked by intermolecular N—H...N and weak N—H...Br hydrogen bonds, generating sheets.

The kinematic accuracy between axes is very important when an NC machine tool performs a contouring cut. This paper describes a theoretical and experimental investigation in which undesired kinematic errors were reduced by means of a microprocessor-based control scheme. A theoretical model representing the relationship between the dynamic behavior and the controller performance in one axis was first developed and then extended to two-axis contouring operations. Based on these relationships, either a closed-loop proportional (P) or proportional-integral (PI) controller can be optimally designed to manipulate the machine tool feed drive system to achieve high precision. Experiments were performed on an existing three-axis NC milling machine that verified the concepts introduced in this paper. The analytical controller design and implementation procedure are also detailed in this paper.

A practical way to achieve machine tool drive system accuracy is through compensation in the position control loop. Various strategies have been developed in which the compensation data are stored either in a computer or by alternative techniques. The approach described in this paper demonstrates how the dominant causes of the inaccuracies in machine tool drive systems can be determined in a simple and straightforward manner and how the compensation data can be generated using a microprocessor-based calibration technique. The proposed method was demonstrated on a Giddings & Lewis Model 10V Numericenter and consists of three major steps: 1) accuracy measurement, 2) error-map representation, and 3) error-map analysis and error cause diagnosis. Accuracy measurement was accomplished by reading both the resolver counts and the output of a laser interferometer which served as a reference (master) scale. The procedure is based on a strategy in which small 0.5 mm (0.020 in.), highly accurate ±2.5 μm ( ± 0.0001 in.) linear displacements of the machine tool table motion are taken as the measurement reference. An ARMA (Autoregressive Moving Average) model of order (16, 15) is the statistically adequate model that fit the data of the angular displacement of the resolver. The Dynamic Data System technique was used for this purpose and it can also be used to represent the error-map function. A spectral analysis of the ARMA model revealed the sources of the kinematic errors.

A microcomputer-based forecasting technique for compensating leadscrew drive kinematic errors by the DDS (Dynamic Data Systems) approach is proposed in this paper. The kinematic error of a particular leadscrew drive system was described by an ARMA(16,15) model. In order to facilitate on-line compensation, an AR(9) model was fit instead of the ARMA model. Both models revealed the same dominate error components and have similar spectral plots.