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Yakugaku Zasshi : Journal of the... 2019Dynamic light scattering (DLS) is used for measuring average particle diameter and particle diameter distribution of nano-sized particles dispersed in liquid. The... (Review)
Review
Dynamic light scattering (DLS) is used for measuring average particle diameter and particle diameter distribution of nano-sized particles dispersed in liquid. The parameters are important characteristics mainly for drug delivery system (DDS) formulations, such as solid in oil (S/O) formulations, liposome formulations, suspension formulations, and emulsion formulations. Herein are described a measurement method and measurement case of particle diameter analysis of medical products using laser light.
Topics: Drug Compounding; Drug Delivery Systems; Dynamic Light Scattering; Emulsions; Liposomes; Nanoparticles; Oils; Particle Size; Pharmacopoeias as Topic; Suspensions
PubMed: 30713234
DOI: 10.1248/yakushi.18-00171-1 -
Academic Pediatrics Aug 2022Individual-, school-, and neighborhood-level support and connectedness may help to mitigate against school suspensions, which have profound health and social...
INTRODUCTION
Individual-, school-, and neighborhood-level support and connectedness may help to mitigate against school suspensions, which have profound health and social consequences. Most research on social connectedness and suspension has focused only on school connectedness, and much less is known about the effects of individual social support and neighborhood-level connectedness on suspension.
METHODS
We examined associations between all three levels of connectedness and suspension in a cross-sectional analysis of a population-based youth sample in Allegheny County, Pennsylvania. The Healthy Allegheny Teen Survey, a county-wide survey of 1813 male and female youth ages 14 to 19, assessed health risk/protective behaviors through random-digit-dialing in 2014. This survey included validated items evaluating each type of support as well as items assessing lifetime history of suspension. Logistic regression models examined associations between suspension and social support, school connectedness, and neighborhood-level cohesion.
RESULTS
In fully adjusted logistic regression models examining associations between suspension and each type of support, youth with high social support had 0.38 times the odds of school suspension compared to youth with low social support (95% confidence interval [CI] 0.19-0.74). High levels of school connectedness and neighborhood-level cohesion were also associated with significantly lower odds of suspension (odds ratio [OR] 0.31, 95% CI 0.18-0.53; OR 0.28, 95% CI 0.16-0.47, respectively). Examining all 3 types of support jointly, school connectedness and neighborhood-level cohesion were significantly inversely related to suspension (OR 0.41, 95% CI 0.24-0.71; OR 0.41, 95% CI 0.23-0.74, respectively).
CONCLUSIONS
Programs that foster connectedness at the individual-, school-, and neighborhood-level may help reduce school suspension.
Topics: Adolescent; Cross-Sectional Studies; Female; Humans; Male; Schools; Social Support; Students; Suspensions; Young Adult
PubMed: 34929388
DOI: 10.1016/j.acap.2021.12.016 -
Advanced Healthcare Materials Apr 2022The extrusion printing of inks into suspension baths is an exciting tool, as it allows the printing of diverse and soft hydrogel inks into 3D space without the need for...
The extrusion printing of inks into suspension baths is an exciting tool, as it allows the printing of diverse and soft hydrogel inks into 3D space without the need for layer-by-layer fabrication. However, this printing process is complex and there have been limited studies to experimentally and computationally characterize the process. In this work, hydrogel inks (i.e., gelatin methacrylamide (GelMA)), suspension baths (i.e., agarose, Carbopol), and the printing process are examined via rheological, computational, and experimental analyses. Rheological data on various hydrogel inks and suspension baths is utilized to develop computational printing simulations based on Carreau constitutive viscosity models of the printing of inks within suspension baths. These results are then compared to experimental outcomes using custom print designs where features such as needle translation speed, defined in this work as print speed, are varied and printed filament resolution is quantified. Results are then used to identify print parameters for the printing of a GelMA ink into a unique guest-host hyaluronic acid suspension bath. This work emphasizes the importance of key rheological properties and print parameters for suspension bath printing and provides a computational model and experimental tools that can be used to inform the selection of print settings.
Topics: Baths; Bioprinting; Computer Simulation; Gelatin; Hydrogels; Ink; Printing, Three-Dimensional; Suspensions
PubMed: 34699689
DOI: 10.1002/adhm.202101679 -
Proceedings of the Royal Society of... Jun 1949
Topics: Female; Humans; Suspensions
PubMed: 18153742
DOI: No ID Found -
Proceedings of the National Academy of... Aug 2022Airborne transmission occurs through droplet-mediated transport of viruses following the expulsion of an aerosol by an infected host. Transmission efficiency results...
Airborne transmission occurs through droplet-mediated transport of viruses following the expulsion of an aerosol by an infected host. Transmission efficiency results from the interplay between virus survival in the drying droplet and droplet suspension time in the air, controlled by the coupling between water evaporation and droplet sedimentation. Furthermore, droplets are made of a respiratory fluid and thus, display a complex composition consisting of water and nonvolatile solutes. Here, we quantify the impact of this complex composition on the different phenomena underlying transmission. Solutes lead to a nonideal thermodynamic behavior, which sets an equilibrium droplet size that is independent of relative humidity. In contrast, solutes do not significantly hinder transport due to their low initial concentration. Realistic suspension times are computed and increase with increasing relative humidity or decreasing temperature. By uncoupling drying and suspended stages, we observe that enveloped viruses may remain infectious for hours in dried droplets. However, their infectivity decreases with increasing relative humidity or temperature after dozens of minutes. Examining expelled droplet size distributions in the light of these results leads to distinguishing two aerosols. Most droplets measure between 0 and 40 µm and compose an aerosol that remains suspended for hours. Its transmission efficiency is controlled by infectivity, which decreases with increasing humidity and temperature. Larger droplets form an aerosol that only remains suspended for minutes but corresponds to a much larger volume and thus, viral load. Its transmission efficiency is controlled by droplet suspension time, which decreases with increasing humidity and decreasing temperature.
Topics: Humans; Humidity; Respiratory Aerosols and Droplets; Suspensions; Virus Diseases; Water
PubMed: 35930663
DOI: 10.1073/pnas.2204593119 -
Antimicrobial Agents and Chemotherapy Jul 2023Invasive fungal infections are a major cause of morbidity and mortality for immunocompromised patients. Posaconazole is approved for treatment and prophylaxis of...
Model Based Estimation of Posaconazole Tablet and Suspension Bioavailability in Hospitalized Children Using Real-World Therapeutic Drug Monitoring Data in Patients Receiving Intravenous and Oral Dosing.
Invasive fungal infections are a major cause of morbidity and mortality for immunocompromised patients. Posaconazole is approved for treatment and prophylaxis of invasive fungal infection in adult patients, with intravenous, oral suspension, and gastroresistant/delayed-released tablet formulations available. In Europe, until very recently, posaconazole was used off-label in children, although a new delayed-release suspension approved for pediatric use is expected to become available soon. A population pharmacokinetic model was developed which uses posaconazole therapeutic drug monitoring data following intravenous and oral dosing in hospitalized children, thus enabling estimation of pediatric suspension and tablet oral bioavailability. In total, 297 therapeutic drug monitoring plasma levels from 104 children were included in this analysis. The final model was a one-compartment model with first-order absorption and nonlinear elimination. Allometric scaling on clearance and volume of distribution was included . Tablet bioavailability was estimated to be 66%. Suspension bioavailability was estimated to decrease with increasing doses, ranging from 3.8% to 32.2% in this study population. Additionally, concomitant use of proton pump-inhibitors was detected as a significant covariate, reducing suspension bioavailability by 41.0%. This is the first population pharmacokinetic study to model posaconazole data from hospitalized children following intravenous, tablet, and suspension dosing simultaneously. The incorporation of saturable posaconazole clearance into the model has been key to the credible joint estimation of tablet and suspension bioavailability. To aid rational posaconazole dosing in children, this model was used alongside published pharmacodynamic targets to predict the probability of target attainment using typical pediatric dosing regimen.
Topics: Adult; Humans; Child; Antifungal Agents; Child, Hospitalized; Biological Availability; Drug Monitoring; Administration, Oral; Invasive Fungal Infections; Tablets; Suspensions
PubMed: 37260401
DOI: 10.1128/aac.00077-23 -
Journal of the Royal Society, Interface Jan 2022Suspension feeders (SFs) evolved a high diversity of mechanisms, sometimes with remarkably convergent morphologies, to retain plankton, detritus and man-made particles...
Suspension feeders (SFs) evolved a high diversity of mechanisms, sometimes with remarkably convergent morphologies, to retain plankton, detritus and man-made particles with particle sizes ranging from less than 1 µm to several centimetres. Based on an extensive literature review, also including the physical and technical principles of solid-liquid separation, we developed a set of 18 ecological and technical parameters to review 35 taxa of suspension-feeding Metazoa covering the diversity of morphological and functional principles. This includes passive SFs, such as gorgonians or crinoids that use the ambient flow to encounter particles, and sponges, bivalves or baleen whales, which actively create a feeding current. Separation media can be flat or funnel-shaped, built externally such as the filter houses in larvaceans, or internally, like the pleated gills in bivalves. Most SFs feed in the intermediate flow region of Reynolds number 1-50 and have cleaning mechanisms that allow for continuous feeding. Comparison of structure-function patterns in SFs to current filtration technologies highlights potential solutions to common technical design challenges, such as mucus nets which increase particle adhesion in ascidians, vanes which reduce pressure losses in whale sharks and changing mesh sizes in the flamingo beak which allow quick adaptation to particle sizes.
Topics: Animals; Biomimetics; Feeding Behavior; Plankton; Sharks; Suspensions
PubMed: 35078340
DOI: 10.1098/rsif.2021.0741 -
International Journal of Pharmaceutical... 2021Metronidazole is indicated for the treatment of trichomoniasis, amebiasis, and anaerobic bacterial infections. The dosage regimen of metronidazole needs to be... (Review)
Review
Metronidazole is indicated for the treatment of trichomoniasis, amebiasis, and anaerobic bacterial infections. The dosage regimen of metronidazole needs to be individualized in the treatment of trichomoniasis, in patients with hepatic impairment, and in pediatric as well as geriatric patients. A review of the therapeutic uses of metronidazole reveals the need for flexibility in dosing. This flexibility is readily achieved using an oral liquid dosage form. However, no commercial liquid dosage form of metronidazole currently exists. Metronidazole is commercially available only as 250-mg and 500-mg film-coated tablets. An extemporaneously compounded suspension from pure drug powder or commercial tablets would provide a convenient option to meet unique patient needs. The purpose of this study was to determine the physicochemical and microbiological stability of extemporaneously compounded metronidazole suspensions in PCCA SuspendIt. This base is a sugar-free, paraben-free, dye-free, and gluten-free thixotropic vehicle containing a natural sweetener obtained from the monk fruit. The study design included two metronidazole concentrations to provide stability documentation over a bracketed concentration range for eventual use by compounding pharmacists. A robust stability-indicating ultra-performance liquid chromatographic assay for the determination of the chemical stability of metronidazole in PCCA SuspendIt was developed and validated. Suspensions of metronidazole were prepared in PCCA SuspendIt at 25-mg/mL and 50-mg/mL concentrations, selected to represent a range within which the drug is commonly dosed. Samples were stored in plastic amber prescription bottles at two temperature conditions (5ÆC and 25ÆC). Samples were assayed initially and on the following time points (days): 7, 14, 28, 42, 59, 90, 122, and 180. Physical data such as pH, viscosity, and appearance were also noted. Microbiological stability was also tested. All measurements were obtained in triplicate. A stable extemporaneous product is defined as one that retains at least 90% of the initial drug concentration throughout the sampling period and is protected against microbial growth. The study showed that metronidazole concentrations did not go below 97% of the label claim (initial drug concentration) at both temperatures studied. No microbial growth was observed. Viscosity and pH values also did not change significantly. This study demonstrates that metronidazole is physically, chemically, and microbiologically stable in PCCA SuspendIt for 180 days in the refrigerator and at room temperature, thus providing a viable, compounded alternative for metronidazole in a liquid dosage form, with an extended beyond-use-date to meet patient needs.
Topics: Administration, Oral; Aged; Child; Chromatography, High Pressure Liquid; Chromones; Drug Compounding; Drug Stability; Drug Storage; Humans; Metronidazole; Suspensions
PubMed: 33798117
DOI: No ID Found -
European Journal of Pharmaceutics and... Mar 2022Rapid precorneal loss of topically applied eye drops limits ocular drug absorption. Controlling release and precorneal residence properties of topical formulations may...
Rapid precorneal loss of topically applied eye drops limits ocular drug absorption. Controlling release and precorneal residence properties of topical formulations may improve ocular drug bioavailability and duration of action. In this study, we evaluated in vivo ocular pharmacokinetics of dexamethasone in rabbits after application of a drug solution (0.01%), suspension (Maxidex® 0.1%), and hydrogels of 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AAc) copolymers. The rabbits received a single eyedrop (solution or suspension) or dexamethasone-loaded hydrogel topically. Dexamethasone in tear fluid was sampled with glass capillaries and quantitated by LC-MS/MS. Higher dexamethasone exposure (AUC) in the tear fluid was observed with the suspension (≈3.6-fold) and hydrogel (12.8-fold) as compared to the solution. During initial 15 min post-application, the highest AUC of dissolved dexamethasone was seen after hydrogel application (368 min*µg/mL) followed by suspension (109.9 min*µg/mL) and solution (28.7 min*µg/mL. Based on kinetic simulations, dexamethasone release from hydrogels in vivo and in vitro is comparable. Our data indicate that prolonged exposure of absorbable dexamethasone in tear fluid is reached with hydrogels and suspensions. Pharmacokinetic understanding of formulation behavior in the lacrimal fluid helps in the design of dexamethasone delivery systems with improved ocular absorption and prolonged duration of action.
Topics: Animals; Chromatography, Liquid; Dexamethasone; Drug Liberation; Hydrogels; Kinetics; Rabbits; Suspensions; Tandem Mass Spectrometry
PubMed: 35121080
DOI: 10.1016/j.ejpb.2022.01.005 -
Sensors (Basel, Switzerland) Aug 2022Cellulose, the most abundant sustainable material on Earth, has excellent mechanical and physical properties, high optical transparency, biocompatibility, and...
Cellulose, the most abundant sustainable material on Earth, has excellent mechanical and physical properties, high optical transparency, biocompatibility, and piezoelectricity. So, it has many possibilities for future materials, and many researchers are interested in its application. In this paper, cellulose nanofiber (CNF) and CNF/polyvinyl alcohol (PVA) films are made, and their vibration energy harvesting is studied. CNF was isolated by chemical and physical methods, and the CNF suspension was cast on a flat substrate to make a film. A cast CNF wet film stayed in a 5 Tesla superconductor magnet for 7 days, which resulted in CNF alignment perpendicular to the magnetic field. To further improve the mechanical properties of the CNF film, mechanical stretching was applied. The CNF suspension was mixed with PVA, giving the film toughness. The cast CNF/PVA wet film was mechanically stretched and dried, which improved the CNF alignment. The fabricated CNF and CNF/PVA films were characterized using scanning electron microscopy and X-ray diffraction to verify the alignment. By stretching, the aligned CNF/PVA film exhibits the largest mechanical properties along the aligned direction. The maximum Young's modulus and tensile strength of the 50% stretched CNF/PVA film are 14.9 GPa and 170.6 MPa, respectively. Finally, a vibration energy harvesting experiment was performed by invoking the piezoelectric behavior of the pure CNF, and 50% stretched CNF/PVA films. The harvester structure was innovated by adopting a cymbal structure, which was beneficial to producing large in-plane strain on the films. The designed cymbal structure was analyzed using ANSYS, and its natural frequency was experimentally verified. The CNF/PVA film performs better vibration energy harvesting than the pure CNF film. The CNF/PVA film is applicable for biocompatible and flexible vibration energy harvesting.
Topics: Cellulose; Nanofibers; Polyvinyl Alcohol; Suspensions; Tensile Strength; Vibration
PubMed: 36016041
DOI: 10.3390/s22166280