Carboxymethyl mungbean starch as a new pharmaceutical gelling agent for topical preparation

An application of carboxymethyl mungbean starch (CMMS) as a gelling agent in the topical pharmaceutical preparation was investigated. CMMS was prepared using specific conditions that yielded a high-viscosity product. Polymer gels and gel bases were prepared at 1-10% (wt/wt), and physicochemical studies were carried out in comparison with four standard gelling agents: carbopol 940 (CP), hydroxypropylmethyl cellulose (HPMC), methyl cellulose (MC), and sodium carboxymethyl cellulose (SCMC). Piroxicam was used as a model drug to study the drug release profile of the gel formulations. The tackless, greaseless, and transparent CMMS gels exhibited pseudoplastic behavior with thixotropy at concentrations less than 5% (wt/wt). At a concentration of 5% (wt/wt) and higher, the semisolid gels showed plastic flow characteristics. Viscosity and X-ray diffraction results indicated a good compatibility between CMMS and the acidic piroxicam. No precipitation of piroxicam or phase separation was observed during a stability test. The release rate of piroxicam from 3% (wt/wt) CMMS gel was 1,003.79 +/- 105.08 microg/cm(2), which was comparable with 947.66 +/- 133.70 microg/cm(2) obtained from a 0.5% (wt/wt) carbopol formulation. The release profiles of both formulations were consistent and remained unchanged after 2 months' storage. Viscosity played an important role in controlling the release rate of low concentration CMMS formulations by regulating the drug diffusion. At a concentration of 5% (wt/wt) CMMS and higher, the release rates of piroxicam were not significantly different. A plausible explanation based on the nature of the gelling agent was proposed. Stability and drug release profiles of CMMS and commercial gelling agents were compared. The results supported the potential use of CMMS as a new, effective gelling agent for topical gel preparation.     

Exploring the importance of the relative solubility of matrix and analyte in MALDI sample preparation using HPLC

New insight into the role of solubility in the sample preparation process for MALDI MS is reported. Reversed-phase gradient HPLC conditions were developed that enable the analysis of a broad range of analyte polarities with a single method. This HPLC method was used to establish a relative polarity scale for a series of 15 MALDI matrix materials, a set of example peptides, and a series of model polymer materials with a broad range of polarity. Examples of each polymer type within the range of 6000-10,000 were analyzed with six matrixes that cover a broad range of polarity using MALDI TOFMS. With regard to polymer signal-to-noise ratio, the matrix and polymer combinations that had a close match of HPLC retention time produced the best MALDI spectra. Conversely, the matrix and polymer combinations that have a large difference in HPLC retention time produced poor MALDI spectra. The results suggest that there is a relationship between polarity (solubility) and effective MALDI sample preparation. The relative HPLC retention time of an unknown polymer can serve as a starting point for predicting the matrix (or range of matrixes) that would be most effective.     

Immunochemical approaches for purification and detection of TNT traces by antibodies entrapped in a sol-gel matrix

A highly sensitive immunochemical method for immunoaffinity purification (IAP) and detection of trace amounts of TNT was developed on the basis of antibodies (Abs) in a ceramic matrix (sol-gel). The study resulted in: (i) a highly sensitive and reproducible TNT ELISA (I50 and I20 values of 0.4 +/- 0.09 ppb and 0.12 +/- 0.03 ppb, respectively; n = 12), which is highly specific to TNT; and (ii) successful entrapment of the Abs that bound free analyte from solution. Binding was found to be highly reproducible, dose dependent, and only slightly (1.2-1.8-fold) lower than that in solution. The entrapped Abs did not leach from the matrix and were tolerant of absolute ethanol, acetone, and acetonitrile. Bound analytes could be easily eluted from the sol-gel matrix at high recoveries. The sol-gel-based IAP method described above introduces a simple one-step procedure that has a high potential to serve as a suitable and convenient immunochromatographic device for cleanup and concentration of TNT from "real field" samples in a manner that complies with both chemical and immunochemical residue analysis methods.     

Comparison of stochastic parametrization approaches in a single-column model

We discuss and test the potential usefulness of single-column models (SCMs) for the testing of stochastic physics schemes that have been proposed for use in general circulation models (GCMs). We argue that although single-column tests cannot be definitive in exposing the full behaviour of a stochastic method in the full GCM, and although there are differences between SCM testing of deterministic and stochastic methods, SCM testing remains a useful tool. It is necessary to consider an ensemble of SCM runs produced by the stochastic method. These can be usefully compared with deterministic ensembles describing initial condition uncertainty and also with combinations of these (with structural model changes) into poor man's ensembles. The proposed methodology is demonstrated using an SCM experiment recently developed by the GCSS (GEWEX Cloud System Study) community, simulating transitions between active and suppressed periods of tropical convection.     

Experimental results for improving the matrix condition using a hybrid optical system

We present preliminary experimental results for implementing the "blurred trajectories" method on three parallel optics (PO) systems. The "main" system and "auxiliary" optics were simple laboratory graded lenses attached to an iris diaphragm. When applying the blurred trajectories method we first show an improvement in the matrix condition, as the matrix condition number decreased in a range of factors of 3 to 418 relative to the main system. Following that, image restoration by weak regularization was performed so that the system matrix condition dominated the restoration process. It was shown that the restoration results of the PO are better than those of the main system and the auxiliary optics separately. In addition, the quality of the restoration follows the system's matrix condition. The improvement in the matrix condition achieved by the PO system improved the immunity to detection noise. Finally, a comparison to Wiener filtering restoration shows that it is also generally inferior to the proposed method.     

Influence of cation-adsorption and sonochemical approaches on the preparation of gold catalyst

Nanosize mesoporous ZrO2 support was synthesized via a solid-state reaction route. A new preparation method involving cation-adsorption and sono-chemical procedure was developed for mesoporous ZrO2 supported nano-gold catalyst.     

Comparison of different approaches for estimation of creep crack initiation

In large components such as rotors defects due to manufacturing processes have to be taken into account and crack assessments based on findings of non-destructive evaluation are necessary. Approaches are used in remaining life estimations, for example:

• Time Dependent Failure Assessment Diagram (TDFAD),

• Two Criteria Diagram (2CD) and

• Nikbin–Smith–Webster-Model (NSW-Model).

The TDFAD approach is currently being developed within the R5 procedures as an alternative to conventional methods for predicting incubation and the early stages of Creep Crack growth. A key requirement of TDFAD approaches is the evaluation of a time dependent creep toughness, denoted K_c mat. The 2CD approach has been developed independently in Germany to assess Creep crack incubation in ferritic steels. This approach uses crack tip and ligament damage parameters, R_K and R_σ, respectively. Furthermore the NSW-Model is employed for the estimation of creep crack initiation by using the creep fracture mechanics parameter C^*. Calculations and used parameters were compared for a ferritic 1CrMoV-steel.     

Comparison of three pharmaceutical products obtained from Mexico and the United States: a case study

In recent years, there has been much debate concerning the relative pros and cons of purchasing medications from foreign markets such as Mexico and Canada. The following study compares the content uniformity and weight variation for three medicinal products, acquired from pharmacies in both Mexico and the United States: amoxicillin capsules (500 mg), amoxicillin/clavulanic acid suspension (400 mg and 57 mg/5 mL, respectively), and furosemide tablets (40 mg). Twenty capsules/tablets were individually weighed and a designated aliquot was taken. Following dissolution in an appropriate solvent and sonication, a sample was taken and analyzed via high performance liquid chromatography (HPLC). The suspensions were prepared according to directions on the label. Five samples of the suspensions were then taken and analyzed via an appropriate HPLC method. The content uniformity for the amoxicillin capsules was found to be 15.4 ± 2.4% and 99.4 ± 9.3%, for Mexican and U.S. capsules, respectively. The percent relative standard deviation (% RSD) for weight variation was found to be 8.7% and 1.5% for capsules obtained from Mexico and the United States, respectively. Content uniformity analysis for the Mexican suspension product resulted in an average of 85.5 ± 1.2% for amoxicillin and 98.6 ± 1.9% for the clavulanic acid content, while the results for the U.S. suspension product were 104.4 ± 3.1% and 117.8 ± 3.6% for amoxicillin and clavulanic acid, respectively. Content uniformity for the furosemide tablets was found to be 90.3 ± 4.8% and 95.6 ± 2.1% for Mexican and U.S. tablets, respectively. The % RSD of weight variation for the Mexican tablets was 2.1%, while the % RSD for the U.S. tablets was found to be 1.0%. From the three products tested, content analysis revealed that the amount of active ingredients for two of the products acquired in Mexico were appreciably less than the concentrations for their U.S. counterparts.     

Development of a simple and practical method for estimating the liquid absorption of pharmaceutical porous materials using a capillary rise technique

Porous materials are attractive substances for designing pharmaceutical particulates. However, understanding the behavior of liquid absorption into the intra-pores and interstices of porous carrier particles is important to effectively manufacture active pharmaceutical ingredients (APIs) using these carriers. In this study, we established a simple and practical method for evaluating the liquid absorption behavior of porous carriers using force tensiometry and a capillary rise technique. Different-sized tablets of porous materials were prepared and evaluated by this method using various solvents to estimate liquid absorption into the intra-particle pores and interstices of the particles. The amount of liquid trapped in the interstices of the particles decreased with decreasing tablet volume, after which the amount of liquid in the intra-particle pores could be estimated. Finally, API-loaded particles were prepared by absorbing the API solution into porous carriers based on the intra-capacity revealed above. No free API was found on the surface of the prepared particles, as it was well absorbed into the intra-particle pores. Collectively, this tensiometer method using different-sized tablets of porous materials appears to be a promising technique for evaluating the liquid absorption characteristics of porous pharmaceutical materials.     

Comparison of dose estimation from occupational exposure to 239Pu using different modelling approaches

Several approaches are available for bioassay interpretation when assigning Pu doses to Mayak workers. First, a conventional approach is to apply ICRP models per se. An alternative method involves individualised fitting of bioassay data using Bayesian statistical methods. A third approach is to develop an independent dosimetry system for Mayak workers by adapting ICRP models using a dataset of available bioassay measurements for this population. Thus, a dataset of 42 former Mayak workers, who died of non-radiation effects, with both urine bioassay and post-mortem tissue data was used to test these three approaches. All three approaches proved to be adequate for bioassay and tissue interpretation, and thus for Pu dose reconstruction purposes. However, large discrepancies are observed in the resulting quantitative dose estimates. These discrepancies can, in large part, be explained by differences in the interpretation of Pu behaviour in the lungs in the context of ICRP lung model. Thus, a careful validation of Pu lung dosimetry model is needed in Mayak worker dosimetry systems.     

One-step preparation of FeCo nanoparticles in a SBA-16 matrix as catalysts for carbon nanotubes growth

Nanocomposites containing FeCo alloy nanoparticles dispersed in a highly ordered 3D cubic Im3m mesoporous silica (SBA-16) matrix were prepared by a novel, single-step templated-assisted sol-gel technique. Two different approaches were used in the synthesis of nanocomposites; a pure SBA-16 sample was also prepared for comparison. Low-angle X-ray diffraction, transmission electron microscopy and N2 physisorption at 77 K show that after metal loading, calcination at 500 degrees C and reduction in H2 flux at 800 degrees C the nanocomposites retain the cubic mesoporous structure with pore size not very different from the pure matrix. X-ray absorption fine structure (EXAFS) analysis at Fe and Co K-edges demonstrates that the FeCo nanoparticles have the typical bcc structure. The final nanocomposites were tested as catalysts for the production of carbon nanotubes by catalytic chemical vapour deposition and high-resolution TEM shows that good quality multi-walled carbon nanotubes are obtained.     

Quantitative determination of acetaminophen in pharmaceutical formulations using differential scanning calorimetry. Comparison with spectrophotometric method

In this paper our previous researches dealing with compatibility, thermoanalytical characterization, the kinetics of thermal degradation of acetaminophen, either pure or contained in some commercial pharmaceutical formulations, have found applications outlets. In a previous investigation the possible interactions between acetaminophen and four excipients contained in the commercial pharmaceutical formulations were tested. As a continuation of this research in the present study an analytical method based on differential scanning calorimetry (DSC) was applied to determine the acetaminophen content of four commercial pharmaceutical formulations. For a fifth drug it was shown that the method is not applicable owing to observed incompatibility with one of the excipients. Finally, the analytical results obtained were compared with those derived from two UV spectrophotometric methods (one, i.e., “direct method,” recommended by the Pharmacopeia and the other based on the first-order derivative UV spectra).     

Monitoring of a pharmaceutical nanomilling process using grating light reflection spectroscopy

An optical diagnostic method, grating light reflection spectroscopy (GLRS), has been demonstrated for the in situ monitoring of properties of heterogeneous matrices in industrial processes. The technique is based on measurements near the critical points of intensity and phase in waves reflected from a transmission diffraction grating in contact with a diagnostic sample. The features contained in the reflection spectrum near these thresholds allow for the simultaneous determination of the real and imaginary parts of the dielectric function of the sample. Using these data, the milling progress of highly concentrated fluid suspensions is observed as the material is milled from approximately 40 mm to 160 nm in diameter. A theoretical model that closely resembles experimentally determined spectra was constructed and applied in combination with principal components analysis (PCA) to demonstrate that GLRS can be used to closely monitor changes in the mean particle size of the nanomilled drug product.     

Comparison of approaches for estimating pipe rupture frequencies for risk-informed in-service inspections

This paper describes the comparative study of two approaches to estimate pipe leak and rupture frequencies for piping. One method is based on a probabilistic fracture mechanistic model while the other one is based on statistical estimation of rupture frequencies from a large database. In order to be able to compare the approaches and their results, the rupture frequencies of some selected welds have been estimated using both of these methods. This paper highlights the differences both in methods, input data, need and use of plant specific information and need of expert judgement. The study focuses on one specific degradation mechanism, namely the intergranular stress corrosion cracking. This is the major degradation mechanism in old stainless steel piping in BWR environment, and its growth is influenced by material properties, stresses and water chemistry.     

Comparison of uncertainty estimates in international metrological and ecological guides

Comparisons have been made on the international ecological guidelines CORINAIR, IPCC, and the GHG Protocol, which implement evaluation of the uncertainties in pollution discharges to the atmosphere, greenhouse gases, and metrological guidelines on estimating the uncertainty of GUM measurements. The main sources of uncertainty are identified and their values are estimated together with their contribution to the general uncertainty in the estimation of greenhouse gas discharges. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 22–26, May, 2007.     

Comparison of ab initio and empirical approaches to the quartz surface

We investigate several possible reconstructions of the (0 0 1) α-quartz surface by using a combinatory approach of classical and ab initio molecular dynamics (MD). Configurational space is efficiently explored by fast classical MD simulations with a semi-empirical three-body potential, which has been shown to be accurate in simulations of the bulk. These runs generate initial structures for further refinement by the accurate quantum MD method of Car–Parrinello (P. Car, M. Parrinello, Phys. Rev. Lett. 55 (1985) 2471). Stable reconstructions of the quartz surface have been produced. They show the same pattern: formation of six- and three-membered rings. The obtained structures were found to be local minima in the classical potential, thereby demonstrating the usefulness of the empirical potential for surface calculations.     

LaBO_3荧光基质材料的低温制备与表征

以水合La(NO_3)_3、H_3BO_3为氧化剂,C_2H_5NO_2为还原剂,采用溶液燃烧法,在理论物质的量之比为3∶3∶5的条件下,制备正交晶系硼酸镧(α-LaBO_3)粉体,探讨不同煅烧温度和不同保温时间对产物的影响;采用X射线衍射(XRD)、扫描电镜(SEM)、荧光光谱分析等方法对制备的粉体进行表征。结果表明:合成α-LaBO_3的最佳条件为温度为750℃,煅烧4h,产物颗粒分布均匀且分散性好,晶胞参数a=0.51033nm,b=0.82508nm,c=0.58674 nm,α-La BO_3粉体可作为基质材料应用于发光粉体的制备。     

Kinetically-calibrated solid-phase microextraction using label-free standards and its application for pharmaceutical analysis

Pre-equilibrium solid-phase microextraction (PE-SPME) has attracted considerable research attention due to shorter sampling times and better temporal resolution than afforded by equilibrium SPME (E-SPME). However, the calibration of PE-SPME is often time-consuming and requires deuterated calibrants, which if available, are often expensive. To address these challenges, we propose a simple but versatile kinetic calibration method, in which nonisotopic (label-free) compounds of interest can supplant the use of deuterated analogues, and the need to determine partitioning coefficients inherent to earlier procedures has been eliminated. Using this approach, both free and total concentrations of analytes can be simultaneously measured within complex sample systems with high accuracy and precision. This calibration method was validated against established E-SPME and solid-phase extraction techniques through the measurement of selected pharmaceuticals in progressively complex matrixes including inorganic buffers, fish blood, and municipal wastewater effluents. This calibration approach may significantly improve time and cost-effectiveness, while improving the application of the SPME approach within highly dynamic systems.     

Improvement of the MALDI-TOF analysis of DNA with thin-layer matrix preparation

A new method of sample preparation was developed for MALDI-TOF-MS analysis of oligonucleotides. First, aqueous DNA samples are dispensed and allowed to dry. Then 6-aza-2-thiothymine matrix dissolved in nonaqueous volatile solvents is applied on top of the DNA residue to form a thin homogeneous film. MALDI-TOF analysis shows such preparation generates much better shot-to-shot and sample-to-sample reproducibility and essentially eliminates the need to search for "hot" spots. The increased homogeneity of the matrix/analyte crystal distribution results in significant improvement for quantitative and high-throughput analyses of DNA. Using this method, isotopically resolved oligonucleotide spectra up to a 24-mer can also be easily obtained in a reflectron instrument. Due to the ease of preparation, this method could be widely useful for a number of applications such as for assays that are performed on surface in vitro, as the thin-layer matrix could be applied directly for MALDI analysis.