Solid State

Materials with the olivine LixMPO4 structure form an important new class of materials for rechargeable Li batteries. There is significant interest in their electronic properties because of the importance of electronic conductivity in batteries for high rate applications. The density of states of LixMPO4 (x = 0, 1 and M = Fe, Mn) has been determined with the ab initio GGA+U method, appropriate for these correlated electron systems. Computed results are compared with the optical gap of LiFePO4, as measured using UV-Vis-NIR diffuse reflectance spectroscopy. The results obtained from experiment (3.8-4.0 eV) and GGA+U computations (3.7 eV) are in very good agreement. However, standard GGA, without the same level of treatment of electron correlation, is shown to make large errors in predicting the electronic structure. It is argued that olivines are likely to be polaronic conductors with extrinsically determined carrier levels and that their electronic conductivity is therefore not simply related to the band gap.

The preparation of three new examples of water insoluble host/guest assemblies of the general composition:[(R4N)(Me3Sn) 2M (CN) 6· zH2O](R= n-propyl or n-pentyl, M= Fe or Co, 0≤ z≤ 2) from likewise polymeric super-Prussian-blue derivatives [(Me3Sn) 3M (CN) ...

The preparation and characterization of Langmulr-Blodgett (LB) films of mesoporphyrin IX dimethylester indium chloride are reported. The utility of complementary experimental techniques such as electron diffraction, polarized visible spectroscopy and cyclic voltammetry in yielding information about molecular orientatton and interactions is highlighted. Our results are consistent w~th verhcal packing of the porphyrin ring on the aqueous subphase and transfer of the material in a similar orientation onto a number of different substrates. From polarized UV-visible spectroscopic measurements an average tilt angle 0 between molecular planes and substrate of 64 ° _+ 15 ° is calculated. An area per molecule on the subphase and m the LB films of 0.55 nm 2 ts obtained from pressure-area curves and coulometrtc measurements respectively. A high degree of crystallimty in the layers is apparent from selected area electron diffraction patterns and the films degrade rapidly on exposure to the electron beam. There is considerable interaction between molecules m the films and this leads to peak broadening in both visible absorption spectra and cyclic voltammograms. An underpotential of 700 mV for the reduction of the porphyrin is consistent with surface potential measurements reported earlier.

We report the effect of average A-site cation radius on the structural, magnetic and electrical properties of electron doped manganite La 0.7 Ce 0.3 MnO 3 thin films. A site cation radius hr A i is varied systematically by partially replacing La C3 ions by smaller Y C3 ions in the parent compound. The carrier doping, i.e. the fraction of tetravalent Ce atoms at the A-site was kept at 30%. A series of La 0.7Kx Y x Ce 0.3 MnO 3 (xZ0, 0.05, 0.1, 0.15 and 0.25) thin films were prepared under identical conditions by using pulsed laser deposition technique. Metal-insulator transition temperature (T p ) and the ferromagnetic Curie temperature (T c ) are found to be decreasing significantly with increasing yttrium concentration, i.e. decreasing hr A i. The resistivity (r) at T p increases by one order of magnitude when the yttrium concentration is increased from xZ0 to 0.25, while magnetization decreases with decreasing hr A i. Magnetoresistance as measured under field of 1 T is significant near T c . Structural analysis reveals the films are having single phase and c-axis lattice parameter decreasing linearly as hr A i decreases. There is no marked difference in surface morphology of samples with different yttrium concentration. From EDX the Y:Ce:Mn ratio were consistent within 5% of the nominal composition. q

The paper describes the formation of Ge nanocrystals in thin thermally grown SiO 2-layers (d ox i100 nm) using implantation of 10 15 ±2 Â 10 16 Ge + /cm 2 and subsequent annealing. Although the implanted Ge depth pro®le is distributed over almost the whole SiO 2 layer, a very narrow band (typical width 5 nm) of Ge nanoclusters very close but well-separated to the Si/SiO 2-interface is formed by self-organization under speci®ed annealing conditions. A possible mechanisms for this self-organization process is discussed including nucleation phenomena, Ostwald ripening and defect-stimulated interface processes. Simple MOS-structures were prepared and the eect of charge storage inside the clusters has been derived from C±V characteristics.

An endcapped stationary phase is prepared by thermal immobilization of poly(methyltetradecylsiloxane) (PMTDS) onto a doubly zirconized silica support followed by endcapping using a mixture of hexamethyldisilazane and trimethylchlorosilane. The preparation of the Si-Zr(PMTDS)ec phase shows good repeatability with RSD a3.0% for carbon loadings and column efficiency. This new stationary phase has a lower density of residual hydroxyl groups, according to spectroscopic methods while basic compounds from the Tanaka and Engelhardt test mixtures are eluted with essentially symmetric peaks. Furthermore, the stability of the Si-Zr(PMTDS)ec stationary phase, measured using an accelerated aging test, is twice as great as the stability of a similar nonendcapped phase. The new phase shows promise for the separation of basic pharmaceuticals.

We propose a double-gate (DG) 1T-DRAM cell combining SONOS type storage node on the back-gate (control-gate) for nonvolatile memory function. The cell sensing margin and retention time characteristics were systematically examined in terms of control-gate voltage (V cg ) and nonvolatile memory (NVM) function. The additional NVM function is achieved by Fowler-Nordheim (FN) tunneling electron injection into the nitride storage node. The injected electrons induce a permanent hole accumulation layer in silicon body which improves the sensing margin and retention time characteristics. To demonstrate the effect of stored electrons in the nitride layer, experimental data are provided using 0.6 lm devices fabricated on SOI wafers.

Single phase ceramics CaCu 3 Ti 4.0 O 12 and CaCu 3 Ti 3.9 O 12 have been prepared using the traditional solid-state reaction method. Compared with the stoichiometric ceramics CaCu 3 Ti 4.0 O 12 , Ti-deficient ceramics CaCu 3 Ti 3.9 O 12 have the larger lattice parameter, the higher force constant, and smaller dielectric constant and the lower dissipation factor, although their fundamental characters of dielectric response are similar. Their characteristic relaxation frequencies are not well fitted with the Arrhenius Law but a tentatively supposed relation. With the Cole-Cole Law, the fitted broadened factors of dissipation peaks are 0.5433 and 0.8651 for CaCu 3 Ti 3.9 O 12 and CaCu 3 Ti 4.0 O 12 , respectively. All facts mentioned above imply that mutually correlated motion of Ti ions or defects may be expected to be responsible for the giant dielectric constant and high dissipation factor of CaCu 3 Ti 4.0 O 12 .

We show that a ballistic quantum transport model based on the effective mass approximation can fairly well describe the I-V characteristics of armchair graphene nanoribbon FETs at all bias conditions, including regimes dominated by direct or band-to-band tunneling, provided first-order non-parabolic corrections be included in the simulation. This is achieved by means of an energy (position) dependent effective mass. The analysis is supported by comparisons with an atomistic tight-binding model.

The crystal structure and the luminescent properties of TlZn(PO3)3 are studied with respect to Tl+ stereochemistry. In this polyphosphate the Tl+ ions are located in tunnels created by the zinc polyphosphate network [Zn(PO3)3]. Actually the thallium atoms are found in a disymmetric configuration and bond calculation allows the determination of the coordination number by oxygen: 6. Nevertheless a large Tl–O distance induces a low stereochemical activity of the 6s2 lone pair. The luminescent properties are analyzed in the context of Fukuda's model. Thermal variations of excitation and emission spectra can be explained by the small influence of the electron–lattice interaction in agreement with the thallium environment.

In the Mediterranean region the fruits of the strawberry tree (Arbutus unedo L.) may be fermented and distilled to produce a traditional beverage very much appreciated in Southern Europe. The aim of the present work was to study the diversity of the yeast population and the killer activity of the isolates identified as Saccharomyces cerevisiae, obtained during solid state industrial fermentations of the arbutus berries. The identification of the isolates was performed by the 5.8S rRNA-ITS region restriction analysis and by sequencing the D1/D2 region of the large subunit of the rRNA gene. At the start of the fermentations, various non-Saccharomyces species were detected including Aureobasidium pullulans, Dothichiza pithyophila, Dioszegia zsoltii, Hanseniaspora uvarum and yeasts belonging to the genera Metschnikowia, Cryptococcus and Rhodotorula. However, as the biological processes progressed the number of different species decreased with S. cerevisiae and Pichia membranaefaciens becoming dominant at advanced stages of the must fermentation that is characterized by high concentrations of ethanol. Forty three isolates identified as S. cerevisiae were tested for killer activity against two sensitive reference strains and Zygosaccharomyces bailii. Their killer sensitivity in relation to five killer referenced toxins (K2, K5, K8, K9 and K10) was also studied. Out of the isolates analyzed, 95.3% were sensitive and 4.7% were tolerant against the killer toxins tested. Only three isolates revealed killer activity against one sensitive strain and two of them against the spoiler yeast Z. bailii. The microbiota obtained revealed an interesting potential to be used as starter cultures to overcome unpredictable uncontrolled fermentations of the arbutus fruits as well as in other applications of biotechnological interest.

The two-part article aimed to investigate poloxamer 407-based microspheres as a novel platform for enhancing and controlling the delivery of atenolol across the oromucosal tissue. In the Part I of the work, atenolol-loaded poloxamers 407 microparticles were prepared by the solvent free spray congealing technology. This approach was feasible upon the high viscosity of the systems allowing for high loaded (20% w/w) non-aggregated microspheres. Several formulations were studied and the results demonstrated that the drug release patterns, solubility data, mucoadhesion to buccal tissue and gelling properties in saliva could be modified by adding different amount of an amphiphilic polymer-lipid excipient (Gelucire(®) 50/13) to poloxamer 407. Particularly, microspheres based only on poloxamer 407 exhibited very high solubility, mucoadhesive strength and gelling behaviour. To assess their potential as matrix for buccal application, the gelling property and the drug release from tablets obta...

Progesterone rapidly dissolves in an aqueous solution containing hydroxypropyl-b-cyclodextrin (HPBCD) at 1:2 molar ratio, forming a soluble inclusion complex. After filtration and freeze-drying of the final solution, the final powder was examined by SEM, DSC, TGA, XRD, Raman, and FTIR spectroscopy. Experimental results confirm that an inclusion complex exists in the solid state and possible structure of the complex is briefly discussed. ß

We have assessed the use of commercial silicon-onsapphire CMOS electronics in control circuits, which could be used to interface with quantum bits at low temperatures. We have characterized n-type MOSFETs, p-type MOSFETs, and an n + -diffusion resistor at 300 K and 4.2 K and extended these studies into the millikelvin regime. Our measurements of dc responses at 300 K, 4.2 K, and subkelvin and transient responses at 300 K and 4.2 K show that these devices favorably operate at low temperatures with minor changes to their 300-K characteristics and no appreciable change to their operating speed. Our results indicate that control circuits based on commercial CMOS devices may successfully be operated at low temperatures for the control and readout of quantum bits.

A dense silica glass was prepared by consolidating a highly dispersed silicic acid powder (particle size o10 nm) with the Spark Plasma Sintering (SPS) technique. The glass was characterized by ellipsometry, transmission electron microscopy (TEM), infrared reflectance and transmittance spectroscopy, as well as by Raman, UV-Vis-NIR and solid-state nuclear magnetic resonance (NMR) spectroscopy. The prototypic sample showed a transmittance of about 63% compared to silica glass in the UV-Vis spectral range. Based on the results of infrared transmittance spectroscopy this lower transparency is due to the comparably high water content, which is about 40 times higher than that in silica glass. 1 H magic-angle spinning (MAS) NMR confirmed an increase in hydroxyl groups in the sample prepared by SPS relative to that of the conventional SiO 2 reference glass. Aside from the comparably high water content, we conclude from the similarity of the IR-reflectance and the 29 Si MAS NMR spectra of the SPS sample and the corresponding spectra of the conventionally prepared silica glass, that the short-and medium-range order is virtually the same in both materials. Raman spectroscopy, however, suggests that the number of three-and four-membered rings is significantly smaller in the SPS sample compared to the conventionally prepared sample. Based on these results we conclude that it is possible to prepare glasses by compacting amorphous powders by the SPS process. The SPS process may therefore enable the preparation of glasses with compositions inaccessible by conventional methods.

Electrical transport properties of PVK (poly N-vinyl carbazole), a polymer exhibiting an intrinsic electroluminescence (EL) in blue region, have been investigated. In particular, resistivity and charge carrier mobility have been assessed by means of I-V measurements and by Field Effect (FET) doping, respectively. Dielectric constant has been also evaluated by means of C-V measurements performed on an ITO/PVK/Al single layer electroluminescent (EL) device. All electrical characterizations, carried out in different environmental conditions to deeply investigate PVK intrinsic conduction mechanisms, allowed to assess the good quality of spin coated PVK thin films. Electroluminescent measurements performed on ITO/PVK/Al and on ITO/PVK/Alq 3 /Al have been also performed. Finally, charge injection mechanisms from the electrodes to PVK have been investigated also as a function of the temperature. Experimental results have been compared with some well known theoretical models.

The effect of layer structure (GaN versus AlGaN cap) and cleaning procedure prior to Sc2O3 or MgO deposition at 100° C were examined for their effects on the long-term bias-stress stability of AlGaN/GaN high electron mobility transistors (HEMTs). Surface cleaning by ...

Ag 3 MoO 3 F 3 )(Ag 3 MoO 4 )Cl was synthesized by hydro(solvato)thermal methods and characterized by single-crystal X-ray diffraction (P3m1; No. 156, Z ¼ 1; a ¼ 7:4488ð6Þ Å , c ¼ 5:9190ð7Þ Å ). The transparent colorless crystals are comprised of chains of distorted fac-MoO 3 F 3 3À octahedra and MoO 4 2À tetrahedra anions, as suggested by the formulas Ag 3 MoO 3 F 3 and Ag 3 MoO 4 + , and are connected through Ag + cations in a polar alignment along the c-axis. One Cl À anion per formula unit serves as a charge balance and connects the two types of chains in a staggered fashion, offset by B 1 2 Â c: In MoO 4 2À , the Mo atom displaces towards a single oxide vertex, and in MoO 3 F 3 3À , the Mo displaces towards the three oxide ligands. The ordered oxide-fluoride ligands on the MoO 3 F 3 3À anion is important to prevent local inversion centers, while the polar organization is directed by the Cl À anion and interchain dipole-dipole interactions. The dipole moments of MoO 3 F 3 3À and MoO 4 2À align in the negative c-axis direction, to give a polar structure with no cancellation of the individual moments. The direction and magnitude of the dipole moments for MoO 3 F 3 3À and MoO 4 2À were calculated from bond valence analyses and are 6.1 and 1.9 debye (10 À18 esu cm) respectively, compared to 4.4 debye for polar NbO 6 octahedra in LiNbO 3 , and 4.5 debye for polar TiO 6 octahedra in KTiOPO 4 (KTP).

Sustaining Moore's Law requires continual transistor miniaturization. Through silicon innovations and breakthroughs, CMOS transistor scaling and Moore's Law will continue at least through early next decade. By combining silicon innovations with other novel nanotechnologies on the same Si platform, it is expected that Moore's Law will extend well into the next decade. This paper describes the most recent advances made in silicon CMOS transistor technology and discusses the challenges and opportunities presented by the recent emerging nanoelectronic devices such as carbon nanotube field-effect transistors (FET), Si-nanowire FETs and III-V FETs for high-performance, low-power logic applications.

A new vanadium(III) phosphate, (NH 4)[V(PO 4)F], has been synthesized by using mild hydrothermal conditions under autogeneous pressure. The crystal structure has been solved from X-ray single crystal data. The compound crystallizes in the Pnna orthorhombic space group, with the unit-cell parameters a ¼ 12:982ð2Þ; b ¼ 10:608ð1Þ; c ¼ 6:4789ð6Þ Å and Z ¼ 8: The final R factors were R 1 ¼ 0:077 [all data] and wR 2 ¼ 0:068: The crystal structure consists of a three-dimensional framework formed by VO 4 F 2 octahedra and tetrahedral (PO 4) 3À phosphate anions. The vanadium(III) cations from the VO 4 F 2 octahedra are linked through the fluorine atoms giving rise to zigzag chains. The ammonium cations are located in the cavities of the structure compensating the anionic charge of the [V(PO 4)F] À inorganic skeleton. The IR spectrum shows the characteristic bands of the phosphate anion. The diffuse reflectance spectroscopy allowed us to calculate the Dq and Racah parameters. The values are Dq ¼ 1540; B ¼ 505 and C ¼ 2460 cm À1. Magnetic measurements indicate the existence of weak ferromagnetic interactions.

The crystal and magnetic structure of RCrO 4 oxides (R=Nd, Er and Tm) has been studied by owder neutron diffraction. These compounds crystallize with the zircon-type structure, showing tetragonal symmetry, space group I4 1 =amd: In the case of NdCrO 4 , magnetic susceptibility measurements reveal the existence of an antiferromagnetic ordering in which both Cr 5+ and Nd 3+ sublattices are involved. This ordering has been explained on the basis of a propagation vector k ¼ 0 and a collinear structure, described by the symmetry mode A x ; the ordered magnetic moments being 0.62 and 0.66 m B at 2 K for Nd 3+ and Cr 5+ , respectively. Magnetic susceptibility and magnetization measurements reveal that both ErCrO 4 and TmCrO 4 behave as ferromagnetic compounds with a Curie temperature of 15 and 18 K, respectively. Rietveld refinement of the neutron diffraction data for ErCrO 4 yields a collinear magnetic structure described with an F x mode. In the case of the TmCrO 4 oxide, the ferromagnetic sublattices of Tm 3+ and Cr 5+ are aligned antiparallel in the a2b plane, while along the c-axis the magnetic moments point to the same direction. In both compounds, the rather small values obtained for the Er 3+ and Tm 3+ ordered moments compared with the theoretical ones have been attributed to crystal field effects. The differences in the ferromagnetic structure of these compounds have been explained as the result of the higher rare-earth anisotropy of Tm 3+ when compared with Er 3+ , for which no magnetic component is present along the c-direction.

In arc fault circuit breakers, the choice of a fault detection sensitivity is generally made as a compromise between speed of detection and avoidance of nuisance trips. By using solid state switching with a variable arc fault detection threshold, the best of both worlds can be obtained. This paper describes baseline experiments on arc fault management through the use of solid state switching. Direct current testing on series arcs and on parallel arcs across carbonized paths suggests that in some cases, an arc event can be actively managed. This allows a reduced level of power to be supplied to a critical system even in the presence of a fault condition.

A new method for predicting optical characteristics of multilayer coatings based on calculated material properties is presented. This method combines the use of the full potential linear-augmented plane wave method (FP-LAPW) within the framework of the Density Functional Theory (DFT) and the optical matrix approach for modeling the multilayer assembly. The simulation process is applied to thin films of the II-VI semiconductors compounds. The optical constants of each thin film are determined by using the first principle calculations. Each layer is represented by the square Abeles matrix, including all necessary data in the calculation of the optical characteristics (as transmittance, reflectance and absorbance). The simulation of multilayer optical response includes the effect of thickness, light polarization and incident angle. The obtained results are helpful in the design of the multilayer systems with required properties. (R. Miloua). cadmium telluride CdTe. These materials are of great interest in many practical applications like window and buffer layers in thin film solar cells [5-8], antireflection coatings [9], light emitting diodes [10,11], displays [12,13], and photovoltaic cells .

The interaction between poly(acrylamide) (PAM) and poly(ethylene glycol) (PEG) in their solid mixture was studied by Fourier transform infrared spectroscopy (FTIR); and their interaction in aqueous solution was investigated by nuclear magnetic resonance spectroscopy (NMR). For the solid PAM/PEG mixtures, an induced shift of the >C¼ ¼O and >NAH in amide group was found by FTIR. These results could demonstrate the formation of intermolecular hydrogen bonding between the amide group of PAM and the ether group of PEG. In the aqueous PAM/PEG solution system, the PAM and PEG associating with each other in water, i.e., the amide group of PAM interacting with the ether group of PEG through hydrogen bonding was also found by 1 H NMR. Furthermore, the effects of different molecular weight of PAM on the strength of hydrogen bonding between PAM and PEG in water were investigated systemically. It was found that the hydrogen bonding interaction between PAM and PEG in water did not increase with the enlargement of the PAM molecular weight as expected. This finding together with the viscosity reduction of aqueous PAM/PEG solution with the PAM molecular weight increasing strongly indicated that PAM molecular chain, especially having high molecular weights preferred to form spherical clews in aqueous PEG solution. Therefore, fewer amide groups in PAM could interact with the ether groups in PEG. Based on these results, a mechanism sketch of the interaction between PAM and PEG in relatively concentrated aqueous solution was proposed. The fact that the phase separation of aqueous PAM/PEG solution occurs while raising the temperature indicates that this kind of hydrogen bonding between PAM and PEG in water is weak and could be broken by controlling the temperature.

Silicon carbide Schottky, merged PiN Schottky (MPS), and PiN diode technologies are modeled for on-state and reverse recovery conditions. The on-state operation of the PiN diode is modeled through four unique regimes of operation, including current densities resulting in emitter recombination, which results in a stored charge plateau during reverse recovery of SiC PiN diodes. An expression for the moving boundary redistribution capacitance is developed to accurately describe the reverse recovery process in PiN diodes. Furthermore, the extraction of stored charge and junction capacitance from transient reverse recovery measurements is also demonstrated for all diode technologies. The on-state operation of Schottky and merged PiN Schottky diodes is described and a method to model the surge current in MPS diodes is discussed. The performance of the model is demonstrated for a commercially available 600 V, 4 A Schottky diode and a 10 kV, 7.5 A PiN diode. Measurements demonstrating the extraction of model parameters and model validation results are included.

FruiteX-B ® -calcium fructoborate (FrxB) plant mineral complex was investigated in this study. Although calcium fructoborate is naturally-occurring and found in commonly ingested fruits and vegetables, the commercially produced FrxB calcium fructoborate complex is formed by a proprietary reaction of boric acid with fructose and calcium carbonate. Liquid and solid-state 13 C and 11 B NMR were utilized in order to establish a baseline standard of FrxB for product quality purposes, to establish a reliable methodology to positively identify and quantify amounts of FrxB present in tablets and capsules, liquids and powdered blends wherein the FrxB may have been mixed with other ingredients, excipients, or adulterants such as maltodextrin or magnesium stearate, and to establish a robust and reliable testing method for the identification and quantification of the mono-and the di-complexes of calcium fructoborate as well as any free borate and/or free fructose that may be present. The molar ratio of the various components of calcium fructoborate was studied by 11 B and 13 C NMR in order to establish the relative amounts of free borate, free fructose, and mono-ester/di-ester complex present in the material. A quantitative 11 B NMR method was developed to enable quantification of the amount of FrxB present in products wherein it had been tableted or encapsulated in combination with other dietary supplement ingredients, or excipients such as magnesium stearate or maltodextrin. A quantitative 13 C NMR method was developed to quantify free fructose content in the complex. Finally, an NMR based product stability study was performed to monitor molecular level stability of the complex at temperatures ranging from 35-70 ºC with exposures lasting from 2-18 hours.

Double-gate devices are best candidates for the MOSFET scaling down to the deca-nanometer range. The motivation of this work is to investigate the coupling effects in FinFETs and to extract the carrier mobility in each of the four possible channels. The coupling of the lateral, front and back interfaces is analyzed based on experimental results in FinFETs with various geometries. The influence of the substrate bias on the front and lateral surface potentials is especially emphasized. The back-gate action is minimized in ultra-narrow fins. Finally, the transport properties at each interface are presented and compared. The electron and hole mobilities are significantly lower on the fin edges than at the top and bottom interfaces.

A Ni, Al hydrotalcite-like compound (Htlc) has been proven an useful host material for an alternative synthesis of a K + -free mixed hexacyanoferrate Ni 1.5 Fe III (CN) 6 , which is very difficult to obtain in bulk. The first stage of the procedure consists in the intercalation of hexacyanoferrate(III) inside the Htlc structure. The intercalated Htlc has been treated with a NiNO 3 solution. The obtained material has been characterized by XRD, XAS Raman and FT-IR spectroscopy. The voltammetric response of the compound obtained after the complete solubilization of the Htlc host shows a typical fingerprint of nickel hexacyanoferrate material with a very low level of potassium. Elemental analysis confirmed the absence of K + and thus the occurrence of K + -free nickel hexacyanoferrate (14% yield).

We report magnetroresistance measurements on superconducting single crystals of K3C60. An analysis of the experimental data yields superconducting state and normal state parameters, including the upper critical field I-I&T), coherence length 5, penetration depth h, scattering time 2, mean free path P, and zero temperature resistivity p(O). Some of the intrinsic single crystal parameters are significinatly different from those extracted from thin film and powder specimens.

Friction stir welding (FSW) is a solid-state joining process which emerged as an alternative technology to be used in high strength alloys that were difficult to join with conventional techniques. Notwithstanding the widespread interest in the possibilities offered by FSW, data concerning the fatigue behaviour of joints obtained using this process still is scarce. In this work, a comparative study between fatigue crack growth behaviour of friction stir welds of 6082-T6 and 6061-T6 aluminium alloys is carried out. Fatigue crack growth curves were determined for cracks growing in different locations of the weldments, including the base material, the heat affected zone and the welded material. Generally, friction stir material exhibited lower strength and ductility properties than the base material. However, an enhanced crack propagation resistance is observed in the welded material. The 6082-T6 and 6061-T6 base materials exhibit very similar crack propagation behaviours. On the other hand the friction stir 6061-T6 material shows lower crack propagation rates than corresponding 6082-T6 friction stir material. Particular features of the distinct microstructures of the welded and surrounding material are illustrated using scanning electron microscopy.

Xylanase production by Aspergillus foetidus MTCC 4898 was carried out under solid state fermentation using wheat bran and anaerobically treated distillery spent wash. Response surface methodology involving Box-Behnken design was employed for optimizing xylanase production. The interactions among various fermentation parameters viz. moisture to substrate ratio, inoculum size, initial pH, effluent concentration and incubation time were investigated and modeled. The predicted xylanase activity under optimized parameters was 8200-8400 U/g and validated xylanase activity was 8450 U/g with very poor cellulase activity. Crude xylanase was used for enzymatic saccharification of agroresidues like wheat straw, rice straw and corncobs. Dilute NaOH and ammonia pretreatments were found to be beneficial for the efficient enzymatic hydrolysis of all the three substrates. Dilute NaOH pretreated wheat straw, rice straw and corncobs yielded 4, 4.2, 4.6 g/l reducing sugars, respectively whereas ammonia treated wheat straw, rice straw and corncobs yielded 4.9, 4.7, 4.6 g/l reducing sugars, respectively. The hydrolyzates were analysed by HPTLC. Xylose was found to be the major end product with traces of glucose in the enzymatic hydrolyzates of all the substrates.

An account is given of various classifications of three-periodic nets. It is convenient to classify nets according to the nature of their maximum-symmetry embeddings. Other classifications, particularly in terms of the tilings that carry the nets, are also discussed. Although there is an infinity of possible nets, for certain types the number of possibilities is limited-there are for example exactly five regular nets. An account is given of the enumerations of various types of special structures such as sphere packings, the nets of simple tilings and self-dual tilings. Some databases of relevant structures and computer programs are described. r

Solid-state polyamidation is an alternative route for polyamide synthesis. Solid-state polyamidation of dodecamethylenediammonium adipate was studied in the presence of acid catalysts. Boric acid proved to be the most effective catalyst, followed by sulphuric acid, so that--even at high reaction rates--the reaction was maintained in the solid state throughout the process. On the other hand, phosphoric acid showed a clearly weaker action resulting eventually in a transition of the process from the solid to the melt state, in accordance with noncatalysed behaviour. In general, catalyst concentration plays a considerable role in the catalytic effectiveness obtained.

Single crystals of uranium intermetallic compound UCo 0:5 Sb 2 were grown by means of the antimony-flux technique. The characterization of the samples has been carried out utilizing single crystal X-ray diffraction and magnetization measurements. UCo 0:5 Sb 2 is found to crystallize in the tetragonal HfCuSi 2-type structure, space group P4=nmm with Z ¼ 2 formula units per cell, and the lattice parameters a ¼ 0:4300ð1Þ and c ¼ 0:8958ð2Þ nm: The refinement of the occupancy parameters and the energy dispersive X-ray analysis have indicated a distinct deficiency on the cobalt sites. The results of magnetization measurements showed that UCo 0:5 Sb 2 orders ferromagnetically below 65 K with a huge magnetocrystalline anisotropy with the c direction being the easy magnetization axis.

The metal oxide semiconductor field effect transistor (MOSFET) is scaling to a ''tunneling epoch'', in which multiple leakage current induced by different tunneling effects exist. The complementary Si-based tunneling transistors are presented in this paper. The working principle of this device is investigated in detail. It is found that the band-to-band tunneling current is be controlled by the gate-to-source voltage. Due to the reverse biased p-i-n diode structure, an ultra-low leakage current is achieved. The sub-threshold swing of TFET is not limited by kt/q, which is the physical limit of the MOSFET. Using the CMOS compatible processes, the complementary TFETs (CTFET) are fabricated on one wafer. From a circuit point of view, the compatibility between TFET and MOSFET enables the transfer of CMOS circuits to CTFET circuits.

X-ray absorption spectroscopy has been used to study the structural and electronic properties of cerium atoms in nanocrystalline cerium oxide. These nanocrystalline cerium oxides were prepared by precipitation followed by the aging process. To increase the particle size, the as-prepared cerium oxides were calcined at various temperatures. The nanocrystalline phase was retained, even when the samples were calcined at 6003C. The analyses of X-ray absorption near edge structures (XANES) for cerium oxides show that the increase in the relative intensity of the transition to 2p4 f 1 5d*L 5nal state and its transition energy shifts toward higher energy are due to the increase in covalence between cerium and oxide ligands with increasing particle size. The extended X-ray absorption 5ne structure (EXAFS) results for cerium oxide show that the third Ce+O shell is degraded and the coordination number around cerium is decreased, resulting in a decrease in the bond distances of R Ce+O and R Ce+ Ce for particle size ( (15 nm. However, when the particle size is increased, the third Ce+O shell started growing and the coordination number around cerium attained normal coordination. The present results provide evidence for the formation of nanocrystalline cerium oxide prepared by precipitation followed by the aging process.

The thermal stability of Na 2 Ti 3 O 7 and Na 2 Ti 6 O 13 , together with that of their protonated forms was investigated. The influence of temperature on the structural behaviour of tri-and hexa-titanates was studied using DTG, XRD, FTIR and FT-Raman. These results were correlated with the nature of the exchangeable cations using elemental analysis and N 2 -sorption. The tunnel structure of Na 2 Ti 6 O 13 revealed a higher thermal stability compared to the layered structure of Na 2 Ti 3 O 7 that shows traces of dimerisation above 800 1C. The sodium forms were observed to be more thermally stable compared to their protonated forms. However, analysis show that 'H 2 Ti 6 O 13 ' is much more thermally stable than the layered H 2 Ti 3 O 7 which go through structural changes above 250 1C and suffer a complete structural collapse into anatase/rutile above 800 1C. It was obvious that thermal stability was significantly influenced by the nature of the exchangeable cations and the degree of ion-exchange. r

NXP's family of SOI-based advanced bipolar CMOS DMOS (A-BCD) technologies is presented. The technology is very successful in automotive, audio and power applications. This paper introduces the technology, the device concepts and the applications. The advantage of BCD technology on SOI is in the ability to have all devices fully dielectrically isolated. This enables various device-biasing conditions (like high side or below substrate voltage), which are not easy to realise on bulk. This creates competitive advantage in the mentioned applications. As an example this enables extreme robust EMC (electro magnetic compatibility) and EMI (electro magnetic immunity) circuitry for CAN (controlled area network), or LIN (local interconnect network) transceivers in automotive. The leakage currents of the devices are much lower compared to bulk. The same holds for parasitic capacitances towards the substrate. LIGBT's can be built without suffering from minority carriers being injected into the substrate. The area of power devices is in general very small due to the usage of the double Resurf principle and trench isolation. This small area pays off for high voltage analogue circuits. Special topics on self-heating and ESD are being treated, where it is demonstrated that performance is comparable to bulk. Three applications where SOI based BCD generates a functionality advantage, are being explained. The SOI based technology is an excellent starting point for development of future products were monolithic solutions can be built with embedded power or even embedded MEMs technology.

The successful application of finite element analysis to ultrafast optoelectronic devices is demonstrated. Finite element models have been developed for both an alloyed-and surface-contact metal-semiconductor-metal photodetectors. The simulation results agree with previously reported experimental data. The alloyed device, despite having a somewhat larger capacitance, has a non-illuminated region of lower resistance with a more-uniform and deeper-penetrating electric field and carrier transport current. The latter explains, in terms of the equivalent lumped parameters, the experimentally observed faster response of the alloyed device. The model is further used to predict improved responsivity, based on electrode spacing and antireflective coating. We project that increasing the depth of the alloyed contact beyond approximately half of the optical penetration depth will not yield significantly improved responsivity.

A novel electrochromic device (ECD) working in mid-to long-wave infrared (IR) region is presented, comprising of a solid-state monolithic thin film system for adjusting heat rejection/receiving levels on attached surfaces. The system is an electrically controllable active emissivity modulator. EclipseVED TM , variable-emissivity ECD, is designed for satellite and spacecraft thermal control, using an active ECD system for long-wave infrared (LWIR) modulation and a passive cold mirror for solar rejection.

The interaction of safranin O (SO) with doublestranded calf thymus DNA was investigated electrochemically, using a DNA-modified glassy carbon (GC-DNA) electrode. The results were compared with those obtained using a bare GC electrode. The formal potential of SO was more negative when using the GC-DNA electrode, although the rate of heterogeneous electron transfer was not altered. The GC-DNA electrode enabled preconcentration of the SO on the electrode surface, despite the fact that the mass transfer effects in the thin DNA layer adsorbed on the surface were still observed. The diffusion coefficient of SO and the binding ratio for the oxidized and reduced forms of the bound species were obtained. A binding isotherm for SO at the GC-DNA electrode was plotted from coulometric titrations, giving a binding constant of 5.8×10 4 L mol −1 .

Silicon-on-insulator wafers with pre-etched cavities provide freedom to MEMS design. We have studied direct bonding and mechanical thinning of pre-etched silicon wafers. We have found out that during the thinning process the flexibility of the diaphragm causes a variation in their thickness. The integrity, thickness variation and shape of thinned diaphragms are dictated by cavity dimensions, SOI thickness, cavity vacuum and thinning process. These variables have been in this study put together to form design rules for cavity-SOI manufacturing. The pre-etched cavities enable the release etching of SOI devices using dry etching. We have demonstrated fabrication and functionality of two different types of MEMS-devices.

The catalyst precursor trans-[RuCl 2 (dppe) 2 ] has been synthesized by solid state reaction of RuCl 3 Á 3H 2 O with tetrabutylammonium chloride (TBAC) and subsequent coordination with 1,2-bis-(diphenylphosphine)ethane (dppe) in dichlromethane solution. Reaction time, yield, work up and cleanness were improved by this method when compared with classical procedures. Use of tetrabutylammonium bromide (TBAB) as catalyst has afforded a novel trans-[RuBrCl(dppe) 2 ] whose crystal structure was analyzed.

The ICH guideline on photostability (ICH Topic Q1B) was published in November 1996 and has been implemented in all three regions (US, EU, and Japan). The guideline describes a useful basic protocol for testing of new drug substances and associated drug products for manufacturing, storage, and distribution, but it does not cover the photostability of drugs under conditions of patient use. The pharmaceutical industry now has considerable experience in designing and carrying out photostability studies within the context of this guideline, and issues have been identified that would benefit from the revision process. The purpose of this commentary is to accomplish the following: (i) highlight issues proposed for consideration in the ICH revision process, (ii) offer a rationale for why these issues may compromise the design of a testing protocol and/or the results of the testing program, and (iii) provide recommendations for clarification of the guideline. ß

Study about application of thyristors -solid state four layers p-n-p-n semicondutors -in the industry, both in manufacture stage and as part of end product. The thyristors are more commonly represented by Silicon Controlled Rectifiers -the SCRs -but are also represented by many authors by TRIACs, DIACs, MOSFETs and others. In thits study, their represented more accuracy than contactors, relays and other devices, specially on high volgate networks and power conversion.

Over the last decade, Diversified Technologies Inc. (DTI) has designed and built solid-state pulse modulators to support high power radar transmitters employing large klystrons and TWT amplifiers. The reliability and performance of these modulators indicate that they can deliver similar benefits to a wide range of high power magnetron oscillators. DTI's modulators use standard circuit components and topologies in a specialized form adapted to insure highly stable operation of magnetron-based radar transmitters. This paper describes several approaches to the design of the modulator circuits, and provides examples of recent fielded transmitters, ranging from low power magnetron systems to turn-key, high power transmitters with multiple TWTs.

The thermolysis of benzenediazonium tetrafluoroborate was studied by thermogravimetry in dynamic mode. The decomposition of [ArN N] + BF 4 − in the solid state with the formation of C 6 H 5 F, BF 3 , C 6 H 6 , and N 2 starts at T > 348 K. The speed of the thermolysis was estimated gravimetrically and by infrared spectroscopy, considering the change of the intensity of the absorption band at 1498 cm −1 , which corresponds to fluorobenzene. The maximal rate of thermolysis observes at the 366.5 K. A kinetic scheme, which includes the formation of a neutral complex [C 6 H 5 δ+ · · ·BF 4 δ− ], is proposed for the thermolysis of arenediazonium tetrafluoroborate. The decomposition of the complex with the formation of free-radical intermediates explains the chain character of the thermolysis.