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Biopolymer blend interactions influence the physical, mechanical and barrier properties of edible packaging. Starch (rice and hydroxypropyl cassava starch mixture), agar and maltodextrin were formulated to control the solubility of edible films. Blend materials were characterized for fluid rheology, solid microstructure, mechanical barrier and physical properties. Agar enhanced solid behavior and governed low temperature gelation of the blends, giving improved film forming ability and hydrophobicity. Flexibility of the films highly depended on integrity of polymer networks. Agar formed continuous networks entangled in starch matrices. Conversely, maltodextrin acted as a filler that reduced mechanical strength at high concentration (>40%) due to interruption of network integrity. Interaction between starch and agar led to poor water solubility that was insignificantly impacted by agar concentration (10% to 30%) due to identical molecular bonding. Maltodextrin produced highly miscible and plasticized starch-agar films and led to reduced mechanical relaxation temperature and shriveling of film structures after mold dipping. Solubility increased linearly with higher maltodextrin concentration. Molecular interaction between maltodextrin and starch/agar matrices insignificantly influenced solubility, while strong interaction between starch and agar highly controlled solubility. Findings clarified the interaction mechanisms and behavior of biological macromolecule materials in fluids and solid matrices for manufacture of edible packaging., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Drug nanocarriers' surface chemistry is often presumed to be uniform. For instance, the polymer surface coverage and distribution of ligands on nanoparticles are described with averaged values obtained from quantification techniques based on particle populations. However, these averaged values may conceal heterogeneities at different levels, either because of the presence of particle sub-populations or because of surface inhomogeneities, such as patchy surfaces on individual particles. The characterization and quantification of chemical surface heterogeneities are tedious tasks, which are rather limited by the currently available instruments and research protocols. However, heterogeneities may contribute to some non-linear effects observed during the nanoformulation optimization process, cause problems related to nanocarrier production scale-up and correlate with unexpected biological outcomes. On the other hand, heterogeneities, while usually unintended and detrimental to nanocarrier performance, may, in some cases, be sought as adjustable properties that provide NPs with unique functionality. In this review, results and processes related to this issue are compiled, and perspectives and possible analytical developments are discussed.

In this study, the migration of antibiotics (norfloxacin, NOR; and sulfamethoxazole, SMX) under simulated resuspension conditions across the sediment-water interface were quantified for two locations in China: point A, located in Meiliang Bay of Lake Taihu, and point B, located in Dapukou of Lake Taihu. The concentrations of suspended solids (SS) in the overlying water amounted to 100, 500, and 1000 mg/L during background, moderate, and strong simulated wind-wave disturbances, respectively. At each SS level, the initial concentrations of the two antibiotics were set to 1, 5, and 10 mg/L. The results showed that both resuspended SS and the initial concentration of antibiotics could influence the migration of NOR in the water-sediment system. Specifically, both higher SS and initial antibiotic concentrations were associated with higher rates of migration and accumulation of NOR from water to sediment. In contrast, the migration of SMX in the water-sediment system was not impacted by SS or initial antibiotic concentration. The adsorption capacities of sediments for NOR and SMX were significantly different at both locations, possibly reflecting differences in cation exchange capacity (CEC) and organic material (OM) contents. In general, higher CEC and OM values were found in sediments with a higher adsorption capacity for the antibiotics. When CEC and OM values of sediments were higher, the adsorption capacity reached up to 51.73 mg/kg. Large differences in the migration from water to sediment were observed for the two antibiotics, with NOR migration rates higher than those of SMX. The accumulation of NOR in surface sediment during resuspension was about 14 times higher than that of SMX. The main reason for this is that the chemical adsorption of NOR is seldom reversible. Overall, this study demonstrates that resuspension of NOR and SMX attached to sediments under simulated wind-wave disturbances can promote the migration of the antibiotics from water to sediment; these results could be useful for assessing the migration and fate of commonly used antibiotics in water-sediment systems., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The number of intramuscularly applied dosage forms has been continuously increasing during the last decades. However, up to date no in vitro dissolution test method for parenteral dosage forms has been described in the Ph. Eur. or USP. It was the aim of this study to investigate dissolution test setups based on the compendial flow-through cell and the reciprocating holder for this purpose. Both apparatuses were equipped with dialysis membranes to accommodate the drug formulation. The suitability of the dissolution method was evaluated by comparing release profiles with blood level curves that were obtained previously in an in vivo study in rats by our group. Aqueous solutions and oily suspensions of paracetamol and prednisolone were tested in vitro that were also applied in the in vivo study. In the case of the aqueous solutions in which no formal dissolution occurs, transport from the applied depot across a dialysis membrane was investigated. While the drug transport across the dialysis membrane of both drugs in aqueous solution was similar in all applied test methods, differences in the release behavior of paracetamol and prednisolone as an oily suspension were observed. This was mainly due to sedimentation of the particles within the oily depot., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Oral liquids are safe alternatives to solid dosage forms, notably for elderly and pediatric patients that present dysphagia. The use of ready-to-use suspending vehicles such as SyrSpend SF PH4 is a suitable resource for pharmacists as they constitute a safe and timesaving option that has been studied often. The objective of this study was to evaluate the stability of 10 commonly used active pharmaceutical ingredients (allopurinol 20 mg/mL; amitriptyline hydrochloride 10 mg/mL; carbamazepine 25 mg/mL; domperidone 5 mg/mL; isoniazid 10 mg/mL; ketoconazole 20 mg/mL; lisinopril 1 mg/mL; naproxen 25 mg/mL; paracetamol [acetaminophen] 50 mg/mL; and sertraline hydrochloride 10 mg/mL) compounded in oral suspensions using SyrSpend SF PH4 as the vehicle throughout the study period and stored both at controlled refrigerated (2°C to 8°C) and room temperature (20°C to 25°C). Stability was assessed by means of measuring the percent recovery at varying time points throughout a 90-day period. The quantification of the active pharmaceutical ingredients was performed by high-performance liquid chromatography through a stability-indicating method. Methods were adequately validated. Forced-degradation studies showed that at least one parameter influenced the stability of the active pharmaceutical ingredients. All suspensions were assayed and showed active pharmaceutical ingredient contents between 90% and 110% during the 90-day study period. Although the forced-degradation experiments led to visible fluctuations in the chromatographic responses, the final preparations were stable in the storage conditions. The beyond-use dates of the preparations were found to be at least 90 days for all suspensions, both for controlled refrigerated temperature and room temperature. This confirms that SyrSpend SF PH4 is a stable suspending vehicle for compounding with a broad range of different active pharmaceutical ingredients for different medical usages., (Copyright© by International Journal of Pharmaceutical Compounding, Inc.)

The objective of this study was to evaluate the feasibility of 10 commonly used active pharmaceutical ingredients (APIs) compounded in oral suspensions using an internationally used suspending vehicle (SyrSpend(®) SF PH4 liquid): (i) amlodipine, (as besylate) 1.0mg/mL; (ii) chloroquine phosphate,15.0 mg/mL; (iii) dapsone, 2.0 mg/mL; (iv) phenytoin, 15.0 mg/mL; (v) pyridoxine hydrochloride, 50.0 mg/mL; (vi) sulfadiazine, 100.0 mg/mL; (vii) sulfasalazine, 100.0 mg/mL; (viii) tetracycline hydrochloride, 25.0 mg/mL; (ix) trimethoprim, 10.0 mg/mL; and (x) zonisamide, 10.0 mg/mL. All suspensions were stored both at controlled refrigeration (2-8 °C) and controlled room temperature (20-25 °C). Feasibility was assessed by measuring the percent recovery at varying time points throughout a 90-day period. API quantification was performed by high-performance liquid chromatography (HPLC-UV), via a stability-indicating method. Given the percentage of recovery of the APIs within the suspensions, the expiration date of the final products (API+vehicle) was at least 90 days for all suspensions with regard to both the controlled temperatures. This suggests that the vehicle is stable for compounding APIs from different pharmacological classes., (Copyright © 2015 Elsevier B.V. All rights reserved.)

We analyze a method recently proposed to retrieve the size, refractive index, and concentration of particles in nonabsorbing nanofluids from measurements of the complex effective refractive index of two dilutions of the nanofluid [Opt. Lett.39, 559 (2014)]. The method uses simple formulas to retrieve the particles' parameters. First, we discuss precautions needed with the new method when inferring the refractive index of the particles from measurements of the imaginary part of the effective refractive index of two dilutions of the original nanofluid. Then we analyze the use of this methodology to obtain some average radius in the size of polydisperse suspensions and in the case of suspensions of weakly absorbing particles. We also perform an error analysis considering fixed errors in measurements and calculating the errors in the retrieved size, refractive index, and concentration of particles. Finally, we characterize experimentally nanofluids of polymeric particles fabricated of poly(methyl-methacrylate) (PMMA) and polystyrene (PS) for which we achieved an uncertainty of 5×10(-3) and 1×10(-2) in the determination of the particle refractive index, respectively, and a precision better than 3% in the determination of their radii.

Laboratory experiments were carried out to study the effects of slow mixing conditions on magnesium hydroxide floc size and strength and to determine the turbidity and total suspended solid (TSS) removal efficiencies during coagulation of highly turbid suspensions. A highly turbid kaolin clay suspension (1,213 ± 36 nephelometric turbidity units (NTU)) was alkalized to pH 10.5 using a 5 M NaOH solution; liquid bittern (LB) equivalent to 536 mg/L of Mg(2+) was added as a coagulant, and the suspension was then subjected to previously optimized fast mixing conditions of 100 rpm and 60 s. Slow mixing speed (20, 30, 40, and 50 rpm) and time (10, 20, and 30 min) were then varied, while the temperature was maintained at 20.7 ± 1 °C. The standard practice for coagulation-flocculation jar test ASTM D2035-13 (2013) was followed in all experiments. Relative floc size was monitored using an optical measuring device, photometric dispersion analyzer (PDA 2000). Larger and more shear resistant flocs were obtained at 20 rpm for both 20- and 30-min slow mixing times; however, given the shorter duration for the former, the 20-min slow mixing time was considered to be more energy efficient. For slow mixing camp number (Gt) values in the range of 8,400-90,000, it was found that the mixing speed affected floc size and strength more than the time. Higher-turbidity removal efficiencies were achieved at 20 and 30 rpm, while TSS removal efficiency was higher for the 50-rpm slow mixing speed. Extended slow mixing time of 30 min yielded better turbidity and TSS removal efficiencies at the slower speeds.

The aim of this work is to present a method based on asymmetric flow-field-flow-fractionation coupled on-line to a static light scattering (AF4-UV-SLS) detector to characterize self-assembled nanofibers (NFs). The method developed herein allows the determination of both the length distribution of the NFs as well as the distribution in terms of aggregation number per unit length (Agg). Given the remaining synthetic challenges of better controlling the structural homogeneity and particle dimensions, the NF length and aggregation number per unit length are becoming essential for the improvement and control of their chemical processes and a better understanding of their properties. The results obtained with this AF4-UV-SLS method indicate that a well-resolved NF length distribution characterization and Agg determination were attained. These results provide critical information concerning the physical properties of the investigated NFs and open the door to the characterization of new self-assembled polymers with various asymmetrical architectures., (Published by Elsevier B.V.)

The article covers results of studies concerning nano- and microparticles in atmospheric suspensions in snow collected in 11 points of Karakan coal extraction cluster (Kouzbass) in winter of 2011-2012. As a reference, a sample was taken on territory of Kouzbass botanical garden of Human Ecology Institute with RASc Siberian Division. All the points studied appeared to be polluted with technogenous suspensions--that proves high ecologic load on atmosphere over all territory of Kouzbass coalfield. Particles found in snow could be placed in decrement order: coal (up to 80%), natural minerals (mostly aluminosilicate and quartz) (up to 10%), vegetable detrital matter, unidentifiable technogenic particles, metals and their compounds (mostly Fe, Ba and Ti). Some areas appeared to frequently present microparticles containing rare-earth metals (rare-earth phosphates and alumophosphates prevail).

Suspension array technology is proposed for the simultaneous quantitative determination of seven kinds of pesticide and veterinary drug residues, namely, atrazine, chloramphenicol, carbaryl, clenbuterol, 17-β-estradiol, imidacloprid, and tylosin. The assay is simple and can be accomplished within 2h without repeated pumping and washing steps unlike conventional suspension arrays. The hapten-protein conjugate-coated beads bind to their complementary biotinylated antibodies using a competitive immunoassay format. The coefficients of determination R(2) for six targets were greater than 0.992, whereas that for atrazine was 0.961, which indicate good logistic correlations. The dynamic ranges for the seven targets in the 7-plex assay ranged from 2 log units to 4 log units(1.60×10(0)-1.64×10(3), 5.12×10(-2)-1.60×10(2), 1.00×10(0)-3.13×10(3), 4.00×10(-1)-4.10×10(2), 4.00×10(-1)-4.10×10(2), 5.12×10(-2)-1.60×10(2), and 2.00×10(0)-4.00×10(2)ngmL(-1)). The minimum detection concentrations of chloramphenicol, carbaryl, clenbuterol and 17-β-estradiol in the suspension array (0.05, 1.00, 0.40 and 0.40 ng mL(-1)) were lower than the corresponding limits of detection (0.25, 6.60, 24.23 and 13.96 ng mL(-1)) of using an indirect competitive enzyme-linked immunosorbent assay. Environmental scanning electron microscope was employed to characterize the bead surface, which directly confirmed the reactions on the beads. The suspension array is more flexible and feasible than ELISA for the fast quantitative analysis of pesticide and veterinary drug residues., (Copyright © 2012 Elsevier B.V. All rights reserved.)

mTHPC is a non polar photosensitizer used in photodynamic therapy. To improve its solubility and pharmacokinetic properties, liposomes were proposed as drug carriers. Binding of liposomal mTHPC to serum proteins and stability of drug carriers in serum are of major importance for PDT efficacy; however, neither was reported before. We studied drug binding to human serum proteins using size-exclusion chromatography. Liposomes destruction in human serum was measured by nanoparticle tracking analysis (NTA). Inclusion of mTHPC into conventional (Foslip(®)) and PEGylated (Fospeg(®)) liposomes does not affect equilibrium serum protein binding compared with solvent-based mTHPC. At short incubation times the redistribution of mTHPC from Foslip(®) and Fospeg(®) proceeds by both drug release and liposomes destruction. At longer incubation times, the drug redistributes only by release. The release of mTHPC from PEGylated vesicles is delayed compared with conventional liposomes, alongside with greatly decreased liposomes destruction. Thus, for long-circulation times the pharmacokinetic behavior of Fospeg(®) could be influenced by a combination of protein- and liposome-bound drug. The study highlights the modes of interaction of photosensitizer-loaded nanovesicles in serum to predict optimal drug delivery and behavior in vivo in preclinical models, as well as the novel application of NTA to assess the destruction of liposomes., (© 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.)

We describe a methodology for determining the volume scattering function β(ψ) of aqueous particle suspensions from measurements with a laboratory multi-angle light scattering instrument called DAWN (Wyatt Technology Corporation). In addition to absolute and angular calibration, the key component of the method is the algorithm correcting for reflection errors that reduce the percent error in β(ψ) from as much as ~300% to <13% at backward scattering angles. The method is optimized and tested with simulations of three-dimensional radiative transfer of exact measurement geometry including the key components of the instrument and also validated experimentally using aqueous suspensions of polystyrene beads. Example applications of the method to samples of oceanic waters and comparisons of these measurements with results obtained with other light scattering instruments are presented.

The resuspension of 65 marine sediments was simulated in the laboratory with elutriates from 30 different sites from the north coast of Spain. The partitioning of Cu, Pb and Zn between sediment and elutriate was studied as a function of different physicochemical characteristics of the sediment: organic matter (OM), fine fraction (FF), redox potential and acid volatile sulfides (AVS). Mean remobilization factors (RF) -calculated as metal concentration in the elutriate (μg/L) divided by metal concentration in the sediment (μg/g dry weight)- were 0.072 for Cu, 0.012 for Pb and 0.071 for Zn. Remobilization of Pb was significantly lower than that of Cu and Zn. Although AVS, OM and FF presented a strong intercorrelation, OM explained great part of the variability on Cu and Pb remobilization while AVS did it for Zn. A multiple regression model considering both OM and AVS explained slightly better the remobilization of Pb and Cu, but not that of Zn., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Microfluidic devices are an emerging technology for processing suspensions in e.g. medical applications, pharmaceutics and food. Compared to larger scales, particles will be more influenced by migration in microfluidic devices, and this may even be used to facilitate segregation and separation. In order to get most out of these completely new technologies, methods to experimentally measure (or compute) particle migration are needed to gain sufficient insights for rational design. However, the currently available methods only allow limited access to particle behaviour. In this review we compare experimental methods to investigate migration phenomena that can occur in microfluidic systems when operated with natural suspensions, having typical particle diameters of 0.1 to 10 μm. The methods are used to monitor concentration and velocity profiles of bidisperse and polydisperse suspensions, which are notoriously difficult to measure due to the small dimensions of channels and particles. Various methods have been proposed in literature: tomography, ultrasound, and optical analysis, and here we review and evaluate them on general dimensionless numbers related to process conditions and channel dimensions. Besides, eleven practical criteria chosen such that they can also be used for various applications, are used to evaluate the performance of the methods. We found that NMR and CSLM, although expensive, are the most promising techniques to investigate flowing suspensions in microfluidic devices, where one may be preferred over the other depending on the size, concentration and nature of the suspension, the dimensions of the channel, and the information that has to be obtained. The paper concludes with an outlook on future developments of measurement techniques., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The spectral mass-specific scattering cross section σ[PIM](λ) is most important for the remote sensing inversion of the concentration of suspended mineral matter in the coastal ocean. This optical parameter is also important in optical theory and therefore the theoretical limits of this parameter are important. There are differing reports in the literature on the magnitude of σ[PIM](λ) and its spectral slope in different coastal ocean systems. To account for and predict these differences, I have applied a model of the size distribution of primary suspended mineral particles and aggregates of these particles to theoretical calculations of σ[PIM](λ). I utilized a model of mineral particle aggregates by Khelifa and Hill [Khelifa, A. and P.S. Hill, J. Hydraul. Res. 44, 390 (2006)] and Latimer's optical model of aggregates [Latimer, P., Appl. Opt. 24, 3231, (1985)]. I have been able to account for the variations in magnitude and spectral slope of σ[PIM](λ). This analysis will apply to not only inverting the concentration of suspended mineral matter but also provides the basis for inverting the processes of coagulation and aggregation of primary mineral particles in determining sedimentation rates, budgets, etc.

In this paper, we evaluate the suitability of Coulter method for detecting and quantifying subvisible particles in protein solutions and compare results with other particle-counting technologies. The effects of key instrument and operational parameters such as aperture diameter, solution conductivity, and cleaning procedures are demonstrated. Degraded and nondegraded intravenous immunoglobulin and human serum albumin were chosen as model proteins and sample types for this evaluation. Multisizer™4 was able to obtain reproducible and linear particle counts; however, customized analysis and cleaning procedures are needed depending on the protein analyzed and the sample type (degraded or nondegraded). The Coulter method consistently detected more particles than micro-flow imaging and light obscuration. The presence of translucent particles likely accounts for this observation because detection by the Coulter method does not depend on the optical properties of the particles or solution., (Copyright © 2011 Wiley-Liss, Inc.)

The need is well recognized for suitable reference populations for calibrating and verifying the size and concentration accuracy of particle analysis instruments for use in the measurement of suspended protein particles in biopharmaceuticals. Polystyrene bead standards are normally used as a reference material for calibrating and validating particle analyzers. However, these standards, unlike protein particles, are easily detected and do not challenge the sensitivity of optical instruments. Groups of instruments verified only with beads can still exhibit significant differences in measuring concentrations of more challenging protein particles. To minimize these and obtain consistent concentration measurements between instruments, reference populations must closely resemble protein aggregates in possessing high transparency and a refractive index close to typical protein matrix fluids. This paper describes work on evaluating a promising reference candidate and the use of this to harmonize the performance of Micro-Flow Imaging instruments. Results show that use of a suitable reference population can significantly increase measurement consistency when multiple instruments are used to characterize the same protein particle suspension., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A new, simple, rapid, and precise RP-HPLC method has been developed and validated for the determination of five cephalosporins, namely, cefalexin, cefoperazone, ceftriaxone, ceftazidime, and cefepime. The method has been applied successfully for simultaneous determination of cefalexin in a binary mixture with sodium benzoate in a suspension, and cefoperazone in a binary mixture with sulbactam in vials. Chromatographic separation was achieved on a Waters microBondapak C18 column (250 x 4.6 mm id, 10 pm particle size) using the mobile phase monobasic potassium phosphate (50 mM, pH 4.6)-acetonitrile (80 + 20, v/v) with UV detection. A flow rate of 1 mL/min was applied. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 30-300, 3-30, and 15-120 microg/mL for the studied cephalosporins, sodium benzoate, and sulbactam, respectively. The optimized method proved to be specific, robust, and accurate for QC of the cited drugs in their pharmaceutical preparations.

Plant cell cultures provide a large potential for the production of secondary metabolites. Through the application of different physical and chemical cell stress factors, we investigated the production of the secondary metabolites in plant cell cultures. The effects of pulsed electric field (PEF) and ethephon on growth and secondary metabolism, particularly anthocyanins and phenolic acids synthesis, were investigated by using suspension culture of Vitis vinifera L. cv. Gamay Fréaux as a model system. Anthocyanins were measured by spectrophotometer and extracellular phenolic acids were determined by high-performance liquid chromatography. The compounds were identified by liquid chromatography-mass spectrometry and nuclear magnetic resonance. After the treatments with PEF and ethephon, the concentrations of anthocyanins and phenolic acids in cell culture were higher than in the control, without loss of biomass. The combination of PEF treatment and ethephon improved secondary metabolites formation. Production levels of extracellular phenolic acids, 3-O-glucosyl-resveratrol were increased by PEF and ethephon treatments. The results show that PEF induced a defense response of plant cells and may have altered the cell/membrane's dielectric properties. PEF, an external stimulus or stress, is proposed as a promising new abiotic elicitor for stimulating secondary metabolites biosynthesis in plant cell cultures.

PURPOSE. Updated information on the stability of compounded thioguanine oral suspensions prepared with currently available ingredients, as well as results of testing to determine if the addition of an antioxidant could extend shelf life by inhibiting formation of guanine, are presented. METHODS. Using triturated thioguanine tablets, three compounded suspensions were prepared: (1) a reference formulation containing methylcellulose and simple syrup, (2) an equivalent formulation using Ora-Plus and Ora-Sweet, and (3) an antioxidant-containing formulation prepared by adding ascorbic acid to the equivalent formulation. The compounded batches were stored at room temperature (19-23 °C). The chemical stability of the suspensions was evaluated immediately after compounding and at weekly intervals by a validated liquid chromatography-mass spectrometry (LCMS) assay method; physical stability was evaluated by regular visual checks and weekly pH testing. RESULTS. As demonstrated by serial LCMS testing, mean thioguanine levels in sampled batches of all three suspensions remained above accepted standards and mean guanine formation remained within acceptable limits for up to 63 days. The addition of ascorbic acid appeared to slow guanine formation but did not significantly extend the shelf life of the suspension. CONCLUSION. Compounded oral suspensions of thioguanine 20 mg/mL exhibited acceptable chemical and physical stability for up to nine weeks at 19-23 °C. The addition of ascorbic acid at a concentration of 0.1% to the suspension was not effective in consistently increasing the shelf life of the thioguanine suspensions.

Laser diffraction (LD) has been used to measure the particle size of pharmaceutical aerosols. In this study, the application of LD for measuring the particle size of a model suspension metered dose inhaler (MDI) containing a hydrofluorocarbon propellant was investigated using a Sympatec LD apparatus with an automatic spray device. In order to obtain meaningful results, test parameters such as spray distance and temperature needed to be optimized for this model formulation and then well-controlled during testing. Using a suitable LD test methodology, it was found that particle size variations as a function of nonvolatile excipient levels as well as changes to the suspended drug substance could be observed and, in some cases, correlated to cascade impaction results. Based on these studies, it is believed that the methodology is a valuable rapid screening tool for investigating variations in or permutations to suspension MDI formulations. Nonetheless, the trends in the LD droplet size are complicated by the presence of drug-free droplets. Consequently, the results are not always consistent with other particle sizing techniques such as cascade impaction in which the droplets associated with drug are evaluated. Therefore, for suspension MDIs, the "in-flight" LD method would probably best be utilized as a complementary sizing technique during formulation development.

We report about a combined structural and magnetometric characterization of self-assembled magnetic nanoparticle arrays. Monodisperse iron oxide nanoparticles with a diameter of 20 nm were synthesized by thermal decomposition. The nanoparticle suspension was spin-coated on Si substrates to achieve self-organized arrays of particles and subsequently annealed at various conditions. The samples were characterized by x-ray diffraction, and bright and dark field high resolution transmission electron microscopy. The structural analysis is compared to magnetization measurements obtained by superconducting quantum interference device magnetometry. We can identify either multi-phase Fe(x)O/γ-Fe(2)O(3) or multi-phase Fe(x)O/Fe(3)O(4) nanoparticles. The Fe(x)O/γ-Fe(2)O(3) system shows a pronounced exchange bias effect which explains the peculiar magnetization data found for this system., (© 2011 IOP Publishing Ltd)

Magnetorelaxometry measurements on suspensions of magnetic beads are demonstrated using a planar Hall effect sensor chip embedded in a microfluidic system. The alternating magnetic field used for magnetizing the beads is provided by the sensor bias current and the complex magnetic susceptibility spectra are recorded as the 2nd harmonic of the sensor response. The complex magnetic susceptibility signal appears when a magnetic bead suspension is injected, it scales with the bead concentration, and it follows the Cole-Cole expression for Brownian relaxation. The complex magnetic susceptibility signal resembles that from conventional magnetorelaxometry done on the same samples apart from an offset in Brownian relaxation frequency. The time dependence of the signal can be rationalized as originating from sedimented beads.

To elucidate important parameters for in vitro toxicity assessment of C(60) and C(70) fullerene colloidal particles, experiments were carried out in culture medium using pulsed field gradient nuclear magnetic resonance (PFG-NMR), asymmetrical flow field-flow fractionation (AFFFF), and dynamic light scattering (DLS) methods. First, the amounts of total and bulk bovine serum albumin (BSA) molecules in C(60) and C(70) fullerene colloidal suspensions were determined using the PFG-NMR and AFFFF methods. Because the amount of bulk BSA molecules in the cell culture medium is a significant factor in inducing cell growth and because BSA can strongly adsorb onto the fullerene particles, this value is an important parameter for toxicological assessment. It was found that most of the BSA molecules are freely diffusing for both fullerene colloidal suspensions, at least in the range of fullerene concentration from 0.0025-0.15 mg mL(-1). Second, structural analysis of the fullerene colloidal nanoparticles was successfully performed using AFFFF-multi angle light scattering (MALS) and DLS methods. Based on the observed light scattering profiles obtained from a narrow size distribution of colloidal particles collected after AFFFF separation, it was estimated that the fullerene colloidal nanoparticles of both C(60) and C(70) did not adopt a hard spherical structure in the culture medium. The results from combined analysis using the AFFFF-MALS and DLS methods also supported this conclusion and indicated that the fullerene colloidal particles adopted a more flexible structure in culture medium. Since carbon nanomaterials with different geometric structures exhibit quite different cytotoxicity and bioactivity, these results are important for in vitro toxicity assessment.

Domestic sewage is a potential source of contamination deteriorating water quality in rivers and coastal environments. The present study determined the concentrations of eight steroids in both filtrate and suspended particulate matter (SPM) samples collected monthly at the eight major riverine runoff outlets of the Pearl River Delta (PRD), South China, from March 2005 to February 2006. The concentration of the eight steroids (sum of which is defined as Sigma(8)steroid) in the filtrate and SPM samples ranged 16.7-1340 ng L(-1) and 0.44-240 microg g(-1), respectively. The filtrate samples contained the highest levels of cholesterol (CHOE) and stigmasterol (STIG) on average, whereas the SPM samples had the largest relative abundances of CHOE and coprostanol (COP). In general, larger proportions of the steroids were associated with SPM than with the filtrate phase. The combined (filtrate plus SPM) concentrations of COP in riverine runoff of the PRD were at the midpoint of the global range in surface water. The concentrations of Sigma(8)steroid and COP in SPM were not significantly correlated with particulate organic carbon (POC), riverine runoff, or SPM concentrations, which indicates the dominance of nonpoint input sources for the occurrence of steroids in the PRD. The annual riverine inputs of Sigma(8)steroid and COP were estimated at 360 and 31.6 tons yr(-1), respectively, and the monthly inputs of both Sigma(8)steroid and COP were positively correlated with monthly runoff discharge. Furthermore, the concentrations of Sigma(8)steroid, COP, and CHOE showed significant temporal and spatial variability. These results can be explained by a combination of climatic characteristics, socioeconomic conditions, and steroid sources. Analyses of the diagnostic indices of COP and background information suggested that riverine runoff from the PRD may have been affected by domestic wastewater, which appeared to be a major COP source to the Pearl River Estuary and South China Sea.

Objective: To study the effects of inoculum, various media, pH value of medium and illumination conditions on the growth of Panax quinquefolium suspension cells and the synthesis of ginsenosides Re, Rb1 and polysaccharides., Method: The suspension cells were obtained through tissue culture by manipulation of inoculum, various media, pH value, and illumination conditions. The contents of ginsenosides Re and Rb1 were determined by HPLC, while the contents of polysaccharide were determined by ultraviolet spectrophotometry., Result: The growth rate of suspension cells was greatly increased when inoculum amount was 25 g x L(-1). The effect of media MS, SH and B5 on suspension cells was observed. MS medium was favorable for cells growth, while B5 medium was favorable for the synthesis of ginsenosides and polysaccharides. The polysaccharide content in three media were higher than that of the cultivations. The pH value showed little influence on the cells growth, medium pH 6.0 enhanced the synthesis of Re and polysaccharides. Illumination could significantly enhance secondary metabolite biosynthesis of suspension cells and promoted slightly in polysaccharide synthesis., Conclusion: The inoculum, various media, pH value of medium and illumination conditions have significant influences on suspension cells growth of P. quinquefolium, secondary metabolite and polysaccharides synthesis.

Beverages such as beer, wine, clear fruit juices, teas, and formulated products with similar ingredients are generally expected by consumers to be clear (free of turbidity) and to remain so during the normal shelf life of the product. Hazy products are often regarded as defective and perhaps even potentially harmful. Since consumers are usually more certain of what they perceive visually than of what they taste or smell, the development of haze in a clear product can reduce the likelihood of repeat purchasing of a product and can have serious economic consequences to a producer. Hazes are caused by suspended insoluble particles of colloidal or larger size that can be perceived visually or by instruments. Hazes in clear beverages can arise from a number of causes, but are most often due to protein-polyphenol interaction. The nature of protein-polyphenol interaction and its effect on haze particles, analysis of haze constituents, and stabilization of beverages against haze formation are reviewed.

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured in the dissolved and suspended particulate phase in the sea-surface microlayer (SML) and subsurface water (SSW) collected from Hong Kong's coastal environment. The concentration ranges (pg/L) for summation sigmaHCHs, summation sigmaDDTs and summation sigmaPCBs in the SSW dissolved phase (DP i.e. sum of truly dissolved and colloidal phase) were 409-940 (mean 602), 774-5583 (mean 1908) and 266-433 (mean 278), respectively. The concentration ranges (pg/L) for summation sigmaHCHs, summation sigmaDDTs and summation sigmaPCBs in SSW suspended particulate matter (SPM) were <5-85 (mean 59), 358-1369 (mean 787) and 85.6-273 (mean 172), respectively. The enrichment factor of PCBs and OCPs in the SML varied between 1.1 and 4.5 for the DP, and 0.4-8.2 for the SPM. The distribution of contaminants between DP and SPM in both the SML and SSW indicates that particulate matter plays an important role in the distribution and fate of DDTs and PCBs, but not for HCH isomers. The Pearl River Estuary is likely to be a major source of contaminants transported to Hong Kong.

A calibration strategy for the continuous monitoring of solvent-mediated phase transition was developed using in situ Raman spectroscopy. Citric acid which exhibits enantiotropy during its anhydrous/monohydrate phase transition was selected as a model organic product. Using 25 samples in suspension, specific calibration of the spectral data was obtained for estimating in-line both the overall solid concentration in suspension and the composition of the solid phase. In addition to such key-measurements, reliable estimates of supersaturation were computed in-line from the mass balance of the solute. In order to validate the technique, anhydrous to monohydrate phase transition experiments were performed in suspensions at 15 degrees C and the kinetic process involved was monitored. Despite the use of various solid concentrations and reactor configurations, both the reproducibility and the reliability of the in situ Raman measurements are shown to be satisfactory.

The aim of this research was to describe the thermal behavior of beta-sitosterol crystals in oil-suspensions with a focus on the role of water during heating. The suspensions were prepared by recrystallization in order to achieve a microcrystalline particle size. The structural changes together with the mechanical properties of the suspensions during heating were studied by using variable temperature X-ray powder diffractometry (VT-XRPD), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). Hydrated beta-sitosterol crystals in an oil-suspension dehydrated, despite the composition of the suspensions, at low temperatures. At high beta-sitosterol concentration, the monohydrate crystal form changed partially to a hemihydrated form, and when only a small amount of water was initially incorporated, the hemihydrate crystal form dehydrated to a mostly anhydrate crystal form. The released water, which was immiscible in the surrounding oil, caused the recrystallization of hydrated beta-sitosterol during cooling. This procedure indicated a reversible dehydration process. Structural and thermal analysis of beta-sitosterol crystals in suspensions, together with mechanical analysis made it possible to understand various physical changes during heating.

In this study, a novel laser diffraction particle size analysis dispersion system, capable of sizing particles in situ within suspension hydrofluoroalkane (HFA) pressurised metered dose inhalers (pMDIs), was developed and tested. The technique was compared to four indirect particle sizing methods commonly used to determine the size of particles suspended in HFA pMDIs. The median volume diameter obtained using laser diffraction of both the salbutamol sulphate and fluticasone propionate suspended either in 2H, 3H-decafluoropentane or perfluoropentane (employed as surrogate propellants) was over one-order of magnitude larger than the particle sizes of the drugs suspended in HFA 134a. In contrast, the "in-flight" particle size using the Sympatec inhaler 2000 laser diffraction equipment undersized the particles, predicting higher delivery efficacy compared to the other sizing methods. However, the size of particles suspended in HFAs derived using the novel pressurised dispersion system, showed a linear correlation with the impaction results, r2=0.8894 (n=10). The novel pressure cell sizing technique proved to be simple to use, has the ability to be automated and was accurate, suggesting it could be an essential tool in the development of new suspension-based pMDI formulations.

The adsorptive stripping voltammetric behaviour of trimethoprim (TMP) was studied at pH 3.8 and 7.0 by linear-sweep (LS) and cyclic voltammetry at the hanging mercury drop electrode. The charges and surface concentrations of the protonated TMP species were determined at both pH values. Taking advantage of the adsorption features of TMP fast voltammetric techniques (LS and square-wave (SW) voltammetry) were applied to the determination of TMP at the 10(-7)mol dm(-3) concentration level (pH 3.8). For these concentrations the relative standard deviations were <2% (N=8) and the detection limit was 10nM (3 ng/mL) for the SW-AdCSV (3s; accumulation time 10s, frequency 100 Hz). The use of SW-adsorptive cathodic stripping voltammetry originated a very fast and sensitive method for the direct analysis of TMP in pharmaceutical suspensions without any matrix effects or interference from sulfamethoxazole. No sample pre-treatments or solvent extraction procedures were needed. The quantitative results were in agreement with the data supplied by the manufacturer.

Atmospheric aerosols were sampled at a coastal site and analyzed for H+, NH+4, Ca++, Mg++, Na+, SO4- -, HCO(-3), Cl- and No3-. The analysis demonstrated that these ions are the main constituents of the aerosols sampled. The correlation coefficients are calculated for each possible pair of anions and cations. Ionic balance in the ambient aerosols indicate that the main compounds existed are in the order of sodium chloride; bicarbonates of calcium and magnesium; sulphates of sodium, magnesium and calcium; and nitrates of sodium, magnesium and calcium. The existence of cations has exceeded the anions which indicate that ionic composition of the aerosols are not very much determined by background marine nature but may also be due to transport of polluted air masses from the surrounding areas.

Polybrominated diphenyl ethers (PBDEs) have been determined in 133 samples of suspended particulate matter (SPM), sediments, sewage treatment plant (STP) influents and effluents, fish and mussels from various locations in The Netherlands, as a part of a large Dutch national study on estrogenic contaminants in the aquatic environment (LOES project). Some PBBs were also analysed but not found in any of the samples at detectable levels. PBDEs and PBBs were included in this study because indications of long term effects on the balance of endocrine systems were found in the literature. High concentrations of decaBDE (up to 4600 g/kg dry weight) were found in SPM from the Western Scheldt. These levels are possibly related to spillage during use of PBDEs in industries upstream the river Scheldt in Belgium. SPM was identified as an important carrier for higher brominated diphenyl ethers in the aquatic environment. DecaBDE was not found at detectable levels in flounder, bream and mussels. The bioaccumulation of decaBDE in these fish and shellfish samples is apparently limited. Lower brominated PBDE congeners (tetra/penta) were also found in the Western Scheldt as well as in the Rhine delta and the river Meuse, but in much lower concentrations than the decaBDE. In contrast with decaBDE, the tetra and pentaBDEs were found in biota. It was concluded that at least a small part of the PBDE can pass STPs.

The element contents of biofilms and suspended particulates in the natural aquatic ecosystem were studied, and the samples were collected in Kunming Lake of the Summer Palace in July and October 1999. The biofilm samples were observed through microscope and scanning electron microscope. Various inhabitants such as sessile bacteria, algae, and protozoa existed in the biofilms. The dry weights of biofilms increased with the longer growth period. The dry weight of biofilm at 1 m depth of water reached to 5.19 mg.cm-2 after the growth time of 78 days. The element contents in biofilm, suspended particulate, and lake water were analyzed by ICP-AES, and the results indicated that the element contents in biofilms were higher than those in the particulates. There was not an evident trend in the element contents of biofilms at the different water depth in the same site and growth time. At three sampling sites, the contents of Ca, Mg, K, Na, Al, Fe, and S in the biofilm samples were similar between 1 m and 1.5 m depth of water, but the contents of Mn, Sr, Ti, P, La, Co, Cu, Pb, Li, Ni, B, Ce, V, Be, and Cr were different in the biofilm samples of 1 m and 1.5 m depth of water. The element contents of biofilms increased with the longer growth time.

Currently, heaves is investigated by exposing susceptible horses to dusty hay. Consequently, the response will be dependent on the organic dust content and composition of the hay. It was hypothesised that the use of a hay dust suspension (HDS) would reduce the variability of the challenge and therefore standardise experimental protocols. Furthermore, analysis of HDS would also permit further investigation of the organic dust components responsible for the response. Three hay dust suspensions (HDS-1, 2 and 3) were prepared for use in the diagnosis and investigation of heaves. HDS were produced from fine dust particles, comprising mostly fungal spores, collected from 3 batches of dusty hay. HDS-1 and 3 were analysed for endotoxin, beta-D-glucan and protein concentrations, general protease activity and enumeration and size distribution of particulates. Protease activity was mainly attributable to a 28 kDa serine protease and to 85 kDa and 160 kDa metalloproteases. The particulate and soluble components of HDS could be aerosolised by jet nebulisation. We therefore conclude that detailed analysis of HDS is possible, that such a challenge system provides a method of standardising experimental protocols and that all components of HDS (both soluble and particulate) can be delivered to the lung using standard nebulisation techniques. For the above reasons, nebulised HDS offers considerable advantages over conventional hay/straw challenge for the diagnosis and investigation of heaves.

A simple and cost effective spectrophotometric method is described for the determination of acyclovir in bulk drug and in formulations. The method is based on the formation of blue coloured chromogen when the drug reacts with Folin-Ciocalteu (F-C) reagent in alkaline medium. The coloured species has an absorption maximum at 760 nm and obeys Beer's law in the concentration range 50-450 microg ml(-1). The absorbance was found to increase linearly with increasing concentration of acyclovir, which is corroborated by the calculated correlation coefficient value of 0.9998 (n = 9). The apparent molar absorptivity and Sandell sensitivity were 1.65 x 10(2) l mol(-1) cm(-1) and 1.36 microg cm(-2), respectively. The slope and intercept of the equation of the regression line are 6.87 x 10(-4) and 8.33 x 10(-3), respectively. The limit of detection was 5.68 microg ml(-1) and the limit of quantification was 18.95 microg ml(-1). The proposed method was successfully applied to the determination of acyclovir in pharmaceutical formulations. The reliability of the assay method was established by parallel determination by standard-addition method, and by recovery studies. The results demonstrated and the procedure is at least as accurate, precise and reproducible (RSD < 2%) as the official method, while being simple and less time consuming. A statistical analysis indicated that there was no significant difference between the results obtained by the proposed procedure and those of the official method.

The goal of the flocculation process is to change the particle size distribution to best suit the subsequent processes. Although several methods exist to evaluate the flocculation process, no single universally accepted method has yet to be developed. The purpose of this paper is to present experiences whereby particle counting was used in the diagnosis and optimization of the flocculation process. A commercially available on-line continuous particle counter has been used in evaluating the design and the operation of this process at two conventional Water Treatment Plants. The evaluation is based on particle dynamics, i.e., the change of the number of small and large particles. Some design deficiencies in the distribution channel and flocculation process have been identified from this method, and thus some operational parameters are suggested for optimum performance. Because the optimum condition may be site-specific, the method presented in this paper will be beneficial in the evaluation of the flocculation process at other water treatment plants.

In this paper an experimental approach of aggregation in natural suspensions is presented. The suspensions are organic-matter-rich waters sampled in a brook which drains peat areas. The aggregation was conducted on raw samples in three different experiments lasting from 2 to 8 days. The particle size distribution (PSD) in the 0.5-10 microm size range was followed with a laser sizer and appeared to be almost constant along the whole experiment duration. Nevertheless, the volume of particles larger than 10 microm increased steadily, showing that aggregation occured. This appeared to be the consequence of a steady-state aggregation which allowed the removal of the whole particle set within a day. The use of an aggregation model adapted to calculations on PSD allowed estimation of the aggregation efficiency for such suspensions.

Biological aerated filters (BAFs) are an attractive process option, particularly when low land usage is required. They can combine BOD, solids and ammoniacal nitrogen removal and can be utilised at both secondary and tertiary stages of wastewater treatment. Media selection is critical in the design and operation of BAFs to achieve effluent quality requirements. Two size ranges, 1.5-3.5 and 2.5-4.5 mm, of a foamed clay called StarLight C were used in pilot-scale reactors. Both performed well as BAF media, with reactor loads up to 12 kg COD m(-3) d and 4 kg suspended solids m(-3) d (based on working volumes). The most consistent effluent was obtained using the smaller medium since, at flow rates above 0.41 min(-1), the BAF using the larger medium produced an effluent containing more than 20 mg l(-1) of suspended solids for over 30 min after backwashing. Up to 70% longer run times, as determined by reaching a set head loss, were recorded for the BAF containing the larger rather than the smaller medium. Additionally, the development of pressure above the smaller medium filter bed tended to be logarithmic rather than linear. Reactor profiles indicated that suspended solids removal did not occur over the full 2.3 m depth of the columns. The BAF containing the smaller medium utilised a mean depth of 1.7 +/- 0.3 m, whereas a mean depth of 2.1 +/- 0.3 m was used by the larger medium BAF. Both the head loss development data and the suspended solids removal profiles indicated that the smaller medium BAF was underperforming as a filter.

New developments in numerical modelling of turbulent and density-affected flow in secondary clarifiers are reported. The sludge blanket is included in the computation domain which allows us to account for sedimentation and resuspension of sludge as well as the growth and diminution of the sludge blanket and at the same time respecting mass conservation. It is shown how strongly the prediction of the sludge-blanket height depends on the approaches to describe the settling behaviour of the sludge and the rheological properties within the sludge blanket. Further, an example of dynamic simulation is presented and discussed. This demonstrates how the sludge blanket behaves during load variation and that instabilities may occur at the interface of sludge blanket and supernatant, potentially resulting in sludge wash-off during transient phases, which is not only during load increase but also during load decrease.

An on-line concentration method has been developed for the analysis of dilute suspensions of macromolecules and particles by flow field-flow fractionation (FFF). This method, termed opposed flow sample concentration (OFSC), uses two opposing flowstreams to focus sample into a narrow band near the inlet of the flow FFF channel. Large sample volumes (up to 1 L) have been successfully loaded, concentrated, and separated in a 1 mL volume flow FFF channel. Concentration factors as high as 10(5) have been achieved. The effectiveness of OFSC flow FFF was demonstrated using mixtures of monodispersed standards such as proteins and polystyrene latex beads. Retention times, peak areas, and resolution are comparable for a 10 mL and a typical 10 microL injection volume. The applicability of the method to environmental studies was demonstrated by a separation of river water colloids.

Objective: To evaluate the physical and chemical stability of a suspension of mycophenolate mofetil (MMF) prepared in the hospital from commercially available MMF capsules., Methods: Suspensions of MMF were prepared at room temperature and stored at 5, 25, 37, and 45 degrees C over a period of 50 to 210 days. The contents of MMF and its degradation product, mycophenolic acid, in the suspension were measured at various time points by HPLC., Results: MMF suspensions were stable (as determined by the presence of > or = 90% of the labeled amount) at 45 degrees C for at least 11 days, at 37 degrees C for at least 28 days, at 25 degrees C for at least 28 days, and at 5 degrees C for at least 210 days. The suspension was also physically stable at 5 degrees C during the entire test period., Conclusions: The compounded MMF suspension was stable for at least 11 days at all the temperatures studied and for as long as 210 days at 5 degrees C. This formulation appears to be clinically acceptable and provides a convenient dosage form for pediatric patients and for adults during the early postoperative period.

A voltammetric method has been developed for the determination of metronidazole in dosage forms. The method is based on the electrochemical reduction of the drug at a glassy carbon electrode activated by applying a new pretreatment. The influence of pH, concentration, scan rate and presence of organic solvent and surfactant has been studied. The current is proportional to the concentration and permits the drug to be determined in the concentration range 2 x 10(-6)-6 x 10(-4) M in Britton-Robinson buffer (pH 10). Furthermore, results obtained by the proposed method have been compared with USP XXIII procedure which involves a HPLC method.

Reproducible particle counting using the light-obscuration technique is often troublesome because no absolute standard is available. Therefore, at the Laboratory of Dutch Pharmacists the "calibration-in-time" method was developed. This method enables checking of the amount of particles counted from a diluted latex suspension as a function of time. A particularity of the method is the one-step dilution procedure. The calibration-in-time method is compared with the particle-counting accuracy test according to the USP < 788 >. Advantages and disadvantages of both methods are discussed.

Cis-parinaric acid is fluorescent when partioned into a lipid environment and its fluorescence is destroyed upon reaction with free radicals. In our study 1-palmitoyl-2-parinoyl-phosphatidylcholine (cis-PnA) has been used to monitor the time-course of liposomal lipid peroxidation, using reverse-phase evaporation vesicles (REV) of different composition exposed to oxidative stress in various conditions. This methodology allowed us to estimate the potential damage produced by two different oxidizing systems, namely hydrogen peroxide (H2O2), a water soluble oxidant, and t-butyl hydroperoxide (t-BHP), a hydrophobic hydroperoxide. Furthermore, we evaluated the protective effects of bilayer-associated antioxidants, namely alpha-tocopherol acetate (alpha-THA), vitamin K1 and beta-carotene, as well as of two antioxidants dissolved in the aqueous bulk solution, that is, biverdin and uric acid. Under our experimental conditions, the results suggest that (i) both oxidizing compounds were able to interact with liposomal PnA leading to decay either of the excitation and of emission spectra of the probe; (ii) hydrogen peroxide seemed to be of most effective among the two stressing agents, when employed at similar concentrations; (iii) the alpha-THA appeared to be a stronger antioxidant than vitamin K1 and beta-carotene, resulting in a decrease of the liposomal membrane stress caused by those two oxidizing agents; (iv) among the water soluble antioxidant compounds, biliverdin displayed a protective effect at least 10 x higher than uric acid; (v) the overall damage, as well as the protection mechanisms, seemed to be dependent either on the lipid composition of the vesicles and on the pH of the liposomal suspension. This relatively easy experimental approach suggests the validity of the use of the bilayer associated fluorescent probe PnA in the monitoring of spontaneous and/or chemically induced liposomal lipid damage.