High-temperature 434 Mhz surface acoustic wave devices based on GaPO4

Research into surface acoustic wave (SAW) devices began in the early 1970s and led to the development of high performance, small size, and high reproducibility devices. Much research has now been done on the application of such devices to consumer electronics, process monitoring, and communication systems. The use of novel materials, such as gallium phosphate (GaPO4), extends the operating temperature of the elements. SAW devices based on this material operating at 434 MHz and up 800 degrees C, can be used for passive wireless sensor applications. Interdigital transducer (IDT) devices with platinum/zirconium metallization and 1.4 microm finger-gap ratio of 1:1 have been fabricated using direct write e-beam lithography and a lift-off process. The performance and long-term stability of these devices has been studied, and the results are reported in this paper.     

Bridge-splitting of trans-[PtCl2(η2-CH2CH2)]2 by weak nucleophiles: Crystal and molecular structure of trans-[PtCl2(η2-CH2CH2)(MeCN)]

Bridge-splitting of trans-[PtCl₂(η²-CH₂CH₂)]₂, 1, by L in dichloromethane yields trans-[PtCl₂(η²-CH₂CH₂)(L)] (L = THF, 2, or MeCN, 3) with bridge-splitting equilibrium constants of 0.0289 ± 0.0007 and 3601 ± 215 mol^?1 dm³, respectively, as determined by UV/Vis measurements. The reaction of 3 in MeCN with Cl^? is essentially quantitative. The crystal structure of trans-[PtCl₂(η²-CH₂CH₂)(CH₃CN)] is reported.     

A Defect Localization Scheme for Cellular Nanocomputers

Computers with device feature sizes of a few nanometers—so-called nanocomputers—are expected within a few decades, but this expectation is accompanied by the realization that the boundary conditions of such systems differ substantially from those of current VLSI-based computers. Prominent among the concerns is the increased degree of permanent defects that will affect nanocomputers, such as defects caused by imperfections at the manufacturing stage, but also defects occurring later, possibly even during the use of these systems. New techniques to deal with defects are called for, but given the huge number of devices involved, such techniques may need to be self-contained: they need be applicable at local levels without outside control, even while computations continue to take place. This paper proposes an important element in such techniques, i.e. the localization of defects among a huge number of devices. It employs a cellular automaton-based architecture, and uses statistical techniques combined with randomly moving configurations in the cellular space to estimate defect locations.

Dynamic Contrast-Enhanced Magnetic Resonance Imaging for the Prediction of Monoclonal Antibody Tumor Disposition

The prediction of monoclonal antibody (mAb) disposition within solid tumors for individual patients is difficult due to inter-patient variability in tumor physiology. Improved a priori prediction of mAb pharmacokinetics in tumors may facilitate the development of patient-specific dosing protocols and facilitate improved selection of patients for treatment with anti-cancer mAb. Here, we report the use of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), with tumor penetration of the contrast agent gadobutrol used as a surrogate, to improve physiologically based pharmacokinetic model (PBPK) predictions of cetuximab pharmacokinetics in epidermal growth factor receptor (EGFR) positive xenografts. In the initial investigations, mice bearing Panc-1, NCI-N87, and LS174T xenografts underwent DCE-MRI imaging with the contrast agent gadobutrol, followed by intravenous dosing of an ¹²⁵Iodine-labeled, non-binding mAb (8C2). Tumor concentrations of 8C2 were determined following the euthanasia of mice (3 h–6 days after 8C2 dosing). Potential predictor relationships between DCE-MRI kinetic parameters and 8C2 PBPK parameters were evaluated through covariate modeling. The addition of the DCE-MRI parameter K^trans alone or K^trans in combination with the DCE-MRI parameter Vp on the PBPK parameters for tumor blood flow (QTU) and tumor vasculature permeability (σ_TU^V) led to the most significant improvement in the characterization of 8C2 pharmacokinetics in individual tumors. To test the utility of the DCE-MRI covariates on a priori prediction of the disposition of mAb with high-affinity tumor binding, a second group of tumor-bearing mice underwent DCE-MRI imaging with gadobutrol, followed by the administration of ¹²⁵Iodine-labeled cetuximab (a high-affinity anti-EGFR mAb). The MRI-PBPK covariate relationships, which were established with the untargeted antibody 8C2, were implemented into the PBPK model with considerations for EGFR expression and cetuximab-EGFR interaction to predict the disposition of cetuximab in individual tumors (a priori). The incorporation of the K^trans MRI parameter as a covariate on the PBPK parameters QTU and σ_TU^V decreased the PBPK model prediction error for cetuximab tumor pharmacokinetics from 223.71 to 65.02%. DCE-MRI may be a useful clinical tool in improving the prediction of antibody pharmacokinetics in solid tumors. Further studies are warranted to evaluate the utility of the DCE-MRI approach to additional mAbs and additional drug modalities.     

Kinetic models for the autocatalytic deprotection of copolymers based on 4-hydroxystyrene and styrene

Poly(tert-butylcarbonyloxystyrene) by itself or as a component in a copolymer decomposes at elevated temperatures (about 130–150°C) to give the free phenolic group, isobutylene, and carbon dioxide. It has been found that the isothermal conversion of the ester (the protected phenol) to the free phenol proceeds slowly at first but accelerates with time so that the rate of reaction increases until more than half the reaction is over. Thus, the pattern of conversion with time is typical of an autocatalytic process. Although the classical model of autocatalysis which we reported earlier gave a qualitative representation of the process, two modifications to the model result in a much better approximation to the actual experimental data. These two experimentally rational modifications take into account the very real decrease in the volume of the reacting system as conversion (deprotection) proceeds and the possibility that the catalyzed (fast) reaction is second order in free phenol. © 1996 John Wiley & Sons, Inc.     

Thermodynamics of gold-rich Au---Zn alloys

Thermodynamic data for gold-zinc alloys with compositions x_Zn = 0.02, 0.04, 0.06, 0.10, 0.15 and 0.20 were obtained using a solid state galvanic cell with calcia stabilized zirconia as electrolyte. The measurements were taken for both solid and liquid alloys. Partial molar thermodynamic quantities of both components as well as integral molar quantities are given. The solidus and liquidus temperatures were obtained from the present measurements. Also given are standard molar free energies of formation of Fe_xO(s), NiO(s), Cu₂O(s) and ZnO(s).     

Purification and properties of polyphenol oxidase from oil bean (Pentaclethra macrophylla Benth) seeds

Polyphenol oxidase extracted from oil bean (Pentaclethra macrophylla) seeds was purified 165-fold over the crude enzyme extract. The apparent molecular weight of the enzyme by gel filtration was 110.8 k ± 9.0 k while SDS-PAGE indicated a single species of molecular weight 28.0 k. A copper content of 1.9 mg g^?1 corresponds to one copper atom for each of the four subunits. The purified enzyme oxidised pyrogallol, catechol, 4-methylcatechol and L-dihydroxyphenylalanine but had low activity towards tyrosine. p-Cresol, caffeic acid and cholorogenic acid were not oxidised. Thio-compounds were strong inhibitors of the enzyme. The phenolic compounds tyrosine, resorcinol and orcinol inhibited catechol oxidation but became oxidised in the process.     

Studies on new non-shrinking,thermally stable,araldite-type photopolymers with pendent arylacryloyl groups III. Photopolymers with pendent cinnamic acid ester and furan acrylic ester groups and their reactions with low molar mass modifiers

Commercially available Araldite?-type polymers have been modified with cinnamic and furan acrylic acid chlorides. The polymers were photochemically crosslinked via a [2 + 2] cycloaddition. The resulting polymers show glass transition temperatures up to 130°C and dielectrical constants of ?_r = 3.0. Therefore, these polymers can be applied as permanent resists in multi-layered wiring structures. Numerous well-defined multifunctional modifiers have been synthesized. The effect of those modifiers on the polymerization and properties of the araldite-type polymers has been studied in some detail.     

The metabolism of several carboxylic acids by lactic acid bacteria

Summary The anaerobic metabolism of citrate, fumarate, gluconate, malate, 2-oxoglutarate and pyruvate by 137 strains of 23 species of lactic acid bacteria was investigated. The bacteria were from various sources (plant material, meat and dairy products, dough and wine) and belonged to the generaLactobacillus, Leuconostoc, Pediococcus, andStreptococcus. The ability of metabolize the acids was determined by thin layer chromatography or by enzymatic analysis after growth of the strains in a glucose-containing medium. All strains metabolized pyruvate and only 12 mainly heterofermentative strains were malate negative. These strains were also unable to decompose citrate. This acid was fermented by 23 strains, all of which metabolized malate. Many lactic acid bacteria reduced 2-oxoglutarate to hydroxyglutarate. The strains ofLactobacillus plantarum did not metabolize 2-oxoglutarate whereas all strains ofLeuconostoc oenos decarboxylated this acid and formed 4-hydroxybutyrate and succinate. Gluconate was fermented by 52 mainly heterofermetative strains. No correlation was observed between the ability to ferment citrate, malate or gluconate.

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Der Stoffwechsel verschiedener Carbonsäuren durch Milchsäurebakterien

Zusammenfassung Durch Dünnschichtchromatographie oder enzymatische Analyse der glucosehaltigen Kulturlösung wurde der Abbau von Citrat, Fumarat, Gluconat, Malat, 2-Oxoglutarat und Pyruvat bei 137 Stämmen von Milchsäurebakterien der GattungenLactobacillus, Leuconostoc, Pediococcus undStreptococcus aus Pflanzenmaterial, Milch- und Fleischprodukten, Teig und Wein untersucht. Pyruvat wurde von allen Stämmen abgebaut, und nur 12 Stämme waren Malat-negativ. Diese Stämme setzten Citrat nicht um, während alle 23 Citrat-abbauenden Bakterien auch Malat verwerteten. 2-Oxoglutarat wurde nur von den Stämmen vonLactobacillus plantarum nicht umgesetzt, während es von den meisten Organismen zu Hydroxyglutarat reduziert wurde. Aber alle Stämme vonLeuconostoc oenos bildeten CO₂, 4-Hydroxybutyrat und Succinat aus 2-Oxoglutarat. Gluconat wurde von 52 meist heterofermentativen Organismen vergoren, aber eine Beziehung zum Stoffwechsel von Malat oder Citrat wurde nicht beobachtet.