De Nugis Groebnerialium 2: Applying Macaulay's Trick in Order to Easily Write a Gröbner Basis

 A trick introduced by Macaulay, in order to blow up a monomial ideal into a point ideal whose maximal ideal is the given monomia ideal, is sligtly generalized to allow to write down a Gr?bner basis whose maximal ideal is a given monomial ideal. Received: December 9, 1999; revised version: November 15, 2002 Keywords: Macaulay's bound, Gr?bner basis.     

The development of dimple-shaped chitosan carrier for ethambutol dihydrochloride dry powder inhaler

Objective: In this study, a dimple-shaped chitosan carrier was developed for delivering the antituberculosis drug ethambutol dihydrochloride (EDH) from a dry powder inhaler (DPI) to the lungs.

Materials and methods: Nanosized drug particles were prepared using nanospray drying. The microsized carrier was developed from a chitosan solution by spray drying. Five formulations were prepared by physically mixing the drug and carrier in different ratios. The physico-chemical properties of the formulations were analyzed using scanning electron microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, ultracentrifugation and a cascade impactor.

Result and discussion: The EDH size was 222?nm and the chitosan carrier size was 1.2?µm. Five formulations, i.e. 1:2, 1:2.5, 1:3.3, 1:5 and 1:10 w/w of the EDH to chitosan carrier were prepared by physical mixing. The chitosan carrier was spherical in shape with a dimpled surface and this provided shallow cavities to which the drug was bound, both within its grooves as well as on its surface. The median adhesion force (50% of drug detachment) for formulations #1 to #5 was between 122 and 993?µN. The mass median aerodynamic diameter of the EDH was between 2.3 and 2.7?μm, with the fine particle fractions (aerosolized particles less than 4.4?μm) of 32–42% of the nominal dose.

Conclusion: We suggest that ethambutol dihydrochloride mixed with a chitosan carrier was suitable for use in a dry powder inhaler for controlling tuberculosis especially in minimizing the risk of multidrug resistant tuberculosis and the possible side effects from EDH.     

Die rechnerische Erfassung der Einflüsse einer auf eine aufgeschrumpfte Bandage wirkenden Tangentialkraft

Zusammenfassung L?βt man auf eine aufgeschrumpfte Bandage eine ?uβere Tangentialkraft einwirken, so entstehen zu beiden Seiten des Kraftangriffspunktes Spannungs- und Dehnungs?nderungen, durch die der hiervon betroffene Bandagenteil, der sog. Einfluβbereich der Tangentialkraft, gegenüber seiner Unterlage ?rtlich verschoben wird. Im Kraftangriffspunkt selbst haben die Tangentialspannung sowie die ?rtliche Verschiebung ihren H?chstwert. Nach Wegnahme der Tangentialkraft geht die Verschiebung infolge der Reibung nicht v?llig wieder zurück. Dies ist die Ursache für das sog. “Wandern” von aufgeschrumpften Zahnradbandagen, insbesondere für das Wandern in axialer Richtung bei Schr?gverzahnung. Es werden Beziehungen für die Gr?βe des Einfluβbereiches sowie für die Verschiebung des Kraftangriffspunktes und die zurückbleibende Restverschiebung nach Wegnahme der Tangentialkraft hergeleitet.     

Safety studies on intravenous infusion of a potent angiogenesis inhibitor: taurocholate-conjugated low molecular weight heparin derivative LHT7 in preclinical models

Context: As a class of angiogenesis inhibitors, heparin conjugates have shown significant effectiveness in several studies.

Objectives: The purpose of our current study is to evaluate the effectiveness and safety of infusing the conjugate of low molecular weight heparin and taurocholate (LHT7), which has been developed as a potent angiogenesis inhibitor.

Methods: To evaluate its safety, the method of intravenous infusion was compared with its i.v. bolus administration. Intravenous infusion was administered at a rate of 400?μl/min/kg of body weight for 30?min. Pharmacokinetic (PK) analysis, organ accumulation, and plasma concentration profiles of LHT7 were measured. The anticancer effect of LHT7 was evaluated in murine and human xenograft models, and preclinical studies were performed in SD rats and beagle dogs.

Results: The results of the PK studies showed reduced organ accumulation in mice and the AUC_(0–96?h) (area under the curve) was increased up to 1485?±?125?h?×?μg/ml. The efficacy, at dose 1?mg/kg/2 d was higher for i.v. infusion than for i.v. bolus administration in both murine and human cancer models. The preclinical studies showed the safety dose of LHT7 is less than 20?mg/kg in SD rats and in the next safety analysis in beagle dogs showed that there were no organ-specific adverse effects in higher doses, such as, 12?mg/kg. LHT7 showed sustained effects with minimized adverse events when administered through i.v. infusion.

Conclusions: LHT7 (i.v. infusion) could be safely used for further clinical development as a multi-targeting anti-angiogenic agent.     

Dependence of the divacancy concentration on the germanium content in p -Si1 ? x Ge x (0 < x < 0.10) alloys irradiated with 5-MeV electrons

The concentration of divacancies in Si_{1 − x} Ge _x solid solutions irradiated with 5-MeV electrons has been studied as a function of the germanium content in the 0 < x < 0.10 interval. It is demonstrated that the probability of the primary radiation-induced defect formation in the alloys bombarded with high-energy electrons weakly depends on the germanium content in the indicated interval. Original Russian Text ? N.A. Matchanov, 2007, published in Pis’ma v Zhurnal Tekhnicheskoĭ Fiziki, 2007, Vol. 33, No. 23, pp. 27–35.     

Development and validation of spectrophotometric and HPTLC methods for simultaneous determination of rosiglitazone maleate and metformin hydrochloride in the presence of interfering matrix excipients

Two simple methods have been developed and validated for the simultaneous determination of rosiglitazone maleate (ROS) and metformin hydrochloride (MET) in synthetic mixtures and coated tablets in a ratio of 1:250 (ROS:MET). The first method was a spectrophotometric one. The minor component, ROS was determined by measuring the values of absorbance at λ_max 312?nm and the D₁ amplitudes at 331?nm where MET shows no absorption contribution. However, absorbance interferences from tablet excipients were successfully corrected by D₁ at 331?nm zero-crossing technique. Study of spectral interference from tablet excipients was included in the text. Standard curves for A_max and D₁ methods were in the concentration range 20.0–80.0?μg?mL^?1. The major component, MET was determined both in binary mixtures and tablets by measuring its A_max at 236?nm. Extensive dilution eliminated any absorption contribution from the coexisting ROS or tablet matrix. Standard curves showed linearity in the concentration range 4.0–12.8?μg?mL^?1. The second method was based on high performance thin layer chromatography (HPTLC) separation of the two drugs followed by densitometric measurements of their spots at 230?nm. The separation was carried out on Merck HPTLC aluminium sheets of silica gel 60 F254 using methanol:water:NH₄Cl 1% w/v (5:4:1 v/v/v) as the mobile phase. Linear calibration graphs of peak area values were obtained versus concentrations in the range of 0.4–2.0?μg?band^?1 and 20.0–100.0?μg?band^?1 for ROS and MET, respectively. According to International Conference on Harmonisation (ICH) guidelines, different validation parameters were verified for the two methods and presented.     

An integer concave minimization approach for the minimum concave cost capacitated flow problem on networks

Formulating the minimum concave cost capacitated network flow problem as an integer concave minimization problem, we establish finite branch and bound algorithms, in which the branching operation is the so–called integral rectangular partition and the bounding procedure is performed by the classical minimum linear cost flow problem on subnetworks. For the special case that the flow cost function is concave on a fixed number of arcs and linear on the others, an upper bound of the running time is given. Received: 19 July 1996 / Accepted: 8 July 1997     

Exponential Lower Bounds for Depth 3 Arithmetic Circuits in Algebras of Functions over Finite Fields

A depth 3 arithmetic circuit can be viewed as a sum of products of linear functions. We prove an exponential complexity lower bound on depth 3 arithmetic circuits computing some natural symmetric functions over a finite field F. Also, we study the complexity of the functions f : D ⁿ →F for subsets D⊂F. In particular, we prove an exponential lower bound on the complexity of depth 3 arithmetic circuits computing some explicit functions f:(F ^*) ⁿ →F (in particular, the determinant of a matrix). Received: July 7, 1998; revised version: January 13, 2000     

Simultaneous determination of methocarbamol and aspirin in presence of their pharmacopeial-related substances in combined tablets using novel HPLC-DAD method

Objective and Significance: Methocarbamol (MET) and aspirin (ASP) are widely used as a muscle relaxant combination. The USP reports guaifenesin (GUA) and salicylic acid (SAL) as related substances and hydrolytic products of MET and ASP, respectively. This work aimed at developing and validating a simple and sensitive RP-HPLC method for the determination of both drugs as well as their related substances (at their pharmacopeial limits) in their bulk powders, laboratory prepared mixtures, and MET-ASP combined tablets. Methods and Results: Chromatographic separation was achieved in less than 9?min with the required resolution, peak symmetry, and accuracy on C₁₈ column using isocratic elution system of diluted acetic acid (pH 3.2): acetonitrile at the ratio of 79: 21, v/v, at a flow rate of 1?mL/min. Detection was achieved with photodiode array at 233?nm for MET, GUA, and SAL and at 273?nm for ASP. The developed method has been validated as per ICH guidelines and the calibration plots were linear over the concentration ranges of 2–150, 0.4–30, 25–450, and 0.2–27?μg/mL for MET, GUA, ASP, and SAL, respectively. Conclusion: The optimized method proved to be specific, robust and precise for the quality control of the studied drugs in pharmaceutical preparations to ascertain that their related substances are not exceeding the permitted pharmacopeial limits.     

Forschungsarbeiten über Werkstoff und Festigkeit

Zusammenfassung Zusammenfassender bericht über 157 Werkstoff-und Festigkeitsfragen betreffende Abhandlungen der Sammlung „Forschungsarbeiten auf dem Gebiete des Ingenieurwesens”—Zur Elastizit?tstheorie—Die Eigenschaften der metallischen Werkstoffe—Verhalten bei statischer Beanspruchung: Elastizit?t und Festigkeit; die plastische Form?nderung; Festigkeit bei h?heren Temperaturen; Form und Festigkeit, Versuche an Probest?ben und an ganzen Maschinen-und Bauteilen—Verhalten bei dynamischer Beanspruchung: Schlagbenspruchung, Schwingungsbeanspruchung—Die H?rte—Sonstige Eigenschaften—Beton und Steine: Alterung, Elastizit?t und Festigkeit, Einflu? der Eisenbewehrungen; Quadern für Brückengelenke—Organische Werkstoffe: Holz, Treibriemen—Zusammenfassung und Schlu?bemerkung. Bei de Abfassung dieser Arbeit wurde ich von den Herren Dr.-Ing.H. Ude, Berlin, und Dr.-Ing.H. Holdt, Darmstadt, wesentlich unterstützt.     

A New Class of Ternary Cocyclic Hadamard Codes

 We present a new construction for p-ary codes meeting the Plotkin bound, for any odd prime p, from any planar function on the additive group of GF(p ^a ). We use the Coulter-Matthews planar functions with p=3 to construct new families of ternary cocyclic codes, and compute their dimensions for a≤6. Received: May 23, 2002; revised version: March 27, 2003 Keywords: Plotkin bound, Cocyclic code, Hadamard code, Planar function.     

Évaluation des propriétés du béton par des variables réduites

Résumé Grandeur sans dimension, le nombre Bu=R/v² σ relie les paramètres fondamentaux des essais ultrasoniques du béton: la résistance R, la vitesse de propagation d'une onde longitudinale v et la masse volumique σ. Le nombre Bu est constant pour des bétons de même composition granulaire qui ont des caractéristiques d'hydratation du ciment différentes. Il ne dépend ni du temps ni des conditions de durcissement. Le nombre Bu dépend: 1° de longueurs (comme les dimensions de l'éprouvette et la longuer d'onde) 2° du facteur de macro-structure δ, qui représente la répartition aléatoire des zones faibles dans le matériau et agit seulement sur la résistance. Cette variable réduite est une donnée nécessaire à l'estimation probabiliste de la résistance et peut être calculée par la théorie des milieux poreux.

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Summary The dependence between the strength of concrete R and the sound velocity v, as well as material density σ-can be expressed by a dimensioless number of mechanical similitude Bu=R/v² σ, denoted by the name of the well-known Polish scientist Bronislaw Bukowski, who was working in the field of concrete technology. Instead of strength the elasticity coefficients can be introduced into Bu number, as its theoretical basis is the formula of wave velocity in elastic materials. The tests carried out on small samples 4/4/16 cm have proved the stability of Bu for the concretes of this kind of structure at various times of hardening and conditions of curing. For the vibrated fine concrete (W/C=0.4) has been found Bu=6.0×10⁻⁴, for cement mortar 1∶3−Bu=5.34×10⁻⁴ The stability of Bukowski's number is a condition of similitude of the macrostructure of concrete and of the way of testing. So Bu depends on two parameters that can be also expressed in the form of dimensionless criteria: the first—grouping the linear dimensions of samples and the wave longitude, the second—determining the macrostrucrure of concrete and expressed by technological data as well as by geometry terms of porous or heterogeneous media. The attempts to determine a simple functional relationship R—v did not take into account the fact, that R only (not v) depends on the random disposition of the weakest places in material. It has been proved that the dispersion of aggregate grains is subjected to the statistical Poisson's distribution. A joint dimensionless structure coefficient λ as exponent in an exponential reliability function has been deduced. λ number takes into consideration not only the random variations or grain distribution, but also the fluctuations, caused by the conditions of production.

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Microporous biodegradable polyurethane membranes for tissue engineering

Microporous membranes with controlled pore size and structure were produced from biodegradable polyurethane based on aliphatic diisocyanate, poly(ε-caprolactone) diol and isosorbide chain extender using the modified phase-inversion technique. The following parameters affecting the process of membrane formation were investigated: the type of solvent, solvent–nonsolvent ratio, polymer concentration in solution, polymer solidification time, and the thickness of the polymer solution layer cast on a substrate. The experimental systems evaluated were polymer–N,N-dimethylformamide–water, polymer–N,N-dimethylacetamide–water and polymer–dimethylsulfoxide–water. From all three systems evaluated the best results were obtained for the system polymer–N,N-dimethylformamide–water. The optimal conditions for the preparation of microporous polyurethane membranes were: polymer concentration in solution 5% (w/v), the amount of nonsolvent 10% (v/v), the cast temperature 23°C, and polymer solidification time in the range of 24–48 h depending on the thickness of the cast polymer solution layer. Membranes obtained under these conditions had interconnected pores, well defined pore size and structure, good water permeability and satisfactory mechanical properties to allow for suturing. Potential applications of these membranes are skin wound cover and, in combination with autogenous chondrocytes, as an “artificial periosteum” in the treatment of articular cartilage defects. Various parts of this study were presented at the European Society for Biomaterials Meeting, Sorrento, Italy, September 11–15, 2005, and at the International Conference on Advanced Materials Design & Development (ICAMDD 2005), Goa, India, December 14–16, 2005. An experimental part of this work was carried out at the Polymer Research Department, AO Research Institute, Clavadelerstrasse 8, CH-7270 Davos, Switzerland.     

Development and optimization of a new processing approach for manufacturing topical liposomes-in-hydrogel drug formulations by dual asymmetric centrifugation

Objective: The objective of the present study was to utilize dual asymmetric centrifugation (DAC) as a novel processing approach for the production of liposomes-in-hydrogel formulations.

Materials and methods: Lipid films of phosphatidylcholine, with and without chloramphenicol (CAM), were hydrated and homogenized by DAC to produce liposomes in the form of vesicular phospholipid gels with a diameter in the size range of 200?300?nm suitable for drug delivery to the skin. Different homogenization processing parameters were investigated along with the effect of adding propylene glycol (PG) to the formulations prior to homogenization. The produced liposomes were incorporated into a hydrogel made of 2.5% (v/v) soluble β-1,3/1,6-glucan (SBG) and mixed by DAC to achieve a homogenous liposomes-in-hydrogel-formulation suitable for topical application.

Results and discussion: CAM-containing liposomes with a vesicle diameter of 282?±?30?nm and polydispersity index (PI) of 0.13?±?0.02 were successfully produced by DAC after 50?min centrifugation at 3500?rpm, and homogenously (Conclusion: We managed to develop a relatively fast and reproducible new method for the production of liposomes-in-hydrogel formulations by DAC.     

Fatigue crack propagation in crystalline polymers: effect of moisture in nylon 66

As part of a study of the effects of crystallinity on fatigue crack propagation (FCP) behaviour in crystalline polymers, the FCP response of nylon 66 was examined as a function of both stress intensity factor range (ΔK) and water content. It was found that FCP rates were exponential functions of ΔK, as expected. However, the FCP rates at constant ΔK decreased as the water content was increased to about 3%; at saturation (8% water), the FCP rates were higher than that observed in dry specimens. Results were interpreted in terms of the incorporation of tightly bound water up to a maximum of one water molecule per two amide groups (at∼ 2% water), followed by the incorporation of loosely bound water (at saturation). The tightly bound water evidently toughens the polymer, while the loosely bound water has a predominantly weakening effect. Examination of fracture surfaces revealed a transition from terminal unstable crack growth (at water contents up to 3%) to tearing (at saturation). Classical fatigue striations were observed only in the specimens containing 2% water—the first time such striations have been unequivocally identified for any crystalline polymer.     

Pharmacodynamic and pharmacokinetic investigation of cyclodextrin-mediated asenapine maleate in situ nasal gel for improved bioavailability

Asenapine maleate (AM) is used in the treatment of schizophrenia. Its oral and sublingual bioavailability is <2% and 35%, respectively, due to first pass metabolism and poor solubility. To avoid first pass metabolism and to enhance solubility at all nasal pH conditions, thermo-responsive in situ nasal gel containing asenapine maleate-hydroxyl propyl β cyclodextrin inclusion complex (AM-HPβCD) was prepared in the present study. Inclusion complex (1:1 molar ratio) was characterized using UV spectroscopy, FITR and XRD techniques. Selected formulation (F8b) contained a thermo-sensitive polymer poloxamer 407 which formed gel at 23%w/v concentration and a mucoadhesive polymer PVP K 30 (0.3%w/v) in temperature range of 29–34?°c. It was analyzed for pH, clarity, gelation temperature, mucoadhesive strength, gel strength and rheological parameters using Anton paar compact rheometer. This formulation was subjected to in vitro drug diffusion study using the Franz diffusion cell. Maximum % drug diffusion was obtained at the end of 120?min (99.1?±?0.44%w/v). Dissolution in simulated nasal fluid was 92.33?±?0.15%w/v at the end of 120?min. Locomotor activity was improved with nasal gel containing AM-HPβCD as compared to AM and AM-HPβCD oral solution in rats. C_max for nasal gel was found to be more (9?ng/ml) as compared to AM-HPβCD (5.5?ng/mL) and oral standard solution (2?ng/ml). T_max was found to be 1.5?h. AUC and thus bioavailability in rats by nasal route was increased by 2.5 fold.     

Quartet Structures of Particles and Quasiparticles in the BCS Model

We study the possibility of multiple paring for more than two particles or two quasiparticles in terms of the BCS model. We consider the multiple pairs of particles in terms of the BCS Hamiltonian for two different ground states: in a quiescent Fermi sea model and in the BCS ground state. In case of quasiparticles, we consider the multiple quasiparticle pairs in terms of the BCS ground state only. Although there is no interaction between Cooper’s type pairs in terms of the BCS Hamiltonian, yet we have shown that four particles or two/four quasiparticles can be paired and form a bound state in the singlet state with just twice the bound state energy of a single Cooper’s pair. In the case of a pair of quasiparticles, the bound state exists as a result of the large quasiparticle density of states and the residual interaction between two quasiparticles which is described by the off-diagonal terms in the BCS Hamiltonian written in terms of quasiparticles. In the case of four particles, the bound state exists only as a result of the Pauli principle and the sharp Fermi edge. In the BCS model, a quartet of bound fermions indeed represents a boson, and the many-particle system of the composite of bosons can undergo the conventional Bose condensation of a boson gas. The temperature of the Bose condensation corresponds to the conventional temperature of Bose condensation for non-interacting bosons where each boson has quadruple mass (4m) and the boson density is one-quarter (n/4) of fermions density. A similar conclusion remains valid in the case of the particle–hole resonance in a quiescent Fermi sea. We have shown that in the particle–hole channel there exists the multiple particle–hole resonance for four particles and four holes in a quiescent Fermi sea model similar to the case of two particles and two holes resonance. We have shown that there is no particle–hole resonance in the case of the BCS ground state because there is no hole-type of excitations in the BCS ground state. Nevertheless we have shown that in the BCS ground state quasiparticle pairs can form bound pairs similar to the Cooper’s pair of particles due to the off-diagonal terms in the BCS Hamiltonian. The bound pairs of quasiparticles exist as a result of extremely large quasiparticle density of states. We also discuss the formation of a quartet of quasiparticles and the Bose condensation of the multiple pairs of quasiparticles.     

The effect of short duration NaCl exposure on the surface pore structure of concrete containing GGBFS

The purpose of this study is to evaluate the effect of chloride-binder interactions on the physical pore structure of concrete containing 0?C60% ground granulated blast furnace slag (GGBFS) as cement replacement. Physical and chemical chloride binder interaction was measured based on chloride binder isotherms. Physical chloride binder interaction was estimated to be the difference between the total binding capacity and chemically bound chloride. In this study it was assumed that the chemical binding is the binding capacity of the alumina phases which was estimated, using differential scanning calorimetry, as the area under the Friedel??s salt peaks. The assumption that chemical binding capacity is controlled by alumina phases is supported by multiple linear regression analysis that was conducted to assess the relationship between Fruendlich isotherm constants and the concrete??s chemical composition. To determine the effect physical and/or chemical chloride-binder interaction on the physical microstructure, paste samples were exposed to distilled water and 0.5?M NaCl solution for 6?h, and the total porosity and pore size distribution was evaluated using mercury intrusion porosimetry. Three key findings from this study are: (i) At a chloride concentration up to 0.5?M, and for mixtures containing 0 and 40% GGBFS the contribution of physically and chemically bound chloride are similar. (ii) At chloride concentrations greater than 0.5?M and less than 1?M, the total bound chloride is predominantly chemically bound for the 40% GGBFS mixture. (iii) Concrete specimens exposed to NaCl solution for 6?h exhibited different pore characteristics in comparison to concrete exposed to distilled water. The differences in the concrete microstructure are not linearly dependant on GGBFS content, but are found to be mutually influenced by the total bound chloride content, the percentage of chemically bound chlorides, and the pore size distribution of the mixture.     

Reduced-basis techniques for rapid reliable optimization of systems described by affinely parametrized coercive elliptic partial differential equations

We present a technique for the rapid and reliable optimization of systems characterized by linear-functional outputs of coercive elliptic partial differential equations with affine (input) parameter dependence. The critical ingredients are: reduced-basis approximation to effect significant reduction in state-space dimensionality; a posteriori error bounds to provide rigorous error estimation and control; “offline/online” computational decompositions to permit rapid evaluation of output bounds, output bound gradients, and output bound Hessians in the limit of many queries; and reformulation of the approximate optimization statement to ensure (true) feasibility and control of suboptimality. To illustrate the method we consider the design of a three-dimensional thermal fin: Given volume and power objective-function weights, and root temperature “not-to-exceed” limits, the optimal geometry and heat transfer coefficient can be determined—with guaranteed feasibility—in only 2.3 seconds on a 500 MHz Pentium machine; note the latter includes only the online component of the calculations. Our method permits not only interactive optimal design at conception and manufacturing, but also real-time reliable adaptive optimal design in operation.