Multilayered Inorganic Microparticles for Tunable Dual Growth Factor Delivery

There is an increasing need to control the type, quantity, and timing of growth factors released during tissue healing. Sophisticated delivery systems offering the ability to deliver multiple growth factors with independently tunable kinetics are highly desirable. Here, a multilayered, mineral coated microparticle (MCMs) platform that can serve as an adaptable dual growth factor delivery system is developed. Bone morphogenetic protein‐2 (BMP‐2) and vascular endothelial growth factor (VEGF) are bound to the mineral coatings with high binding efficiencies of up to 80%. BMP‐2 is firstly bound onto a 1^st mineral coating layer; then VEGF is bound onto a 2^nd mineral coating layer. The release of BMP‐2 is sustained over a period of 50 days while the release of VEGF is a typical two‐phase release with rapid release in the first 14 days and more sustained release for the following 36 days. Notably, the release behaviors of both growth factors can be independently tailored by changing the intrinsic properties of the mineral coatings. Furthermore, the release of BMP‐2 can be tuned by changing the thickness of the 2^nd layer. This injectable microparticle based delivery platform with tunable growth factor release has immense potential for applications in tissue engineering and regenerative medicine.     

Laboratory characterization of an aerosol chemical speciation monitor with PM2.5 measurement capability

The Aerodyne Aerosol Chemical Speciation Monitor (ACSM) is well suited for measuring non-refractory particulate matter up to approximately 1.0 µm in aerodynamic diameter (NR-sub-PM₁). However, for larger particles the detection efficiency is limited by losses in the sampling inlet system and through the standard aerodynamic focusing lens. In addition, larger particles have reduced collection efficiency due to particle bounce at the vaporizer. These factors have limited the NR-sub-PM₁ ACSM from meeting PM_2.5 (particulate matter with aerodynamic diameter smaller than 2.5 µm) monitoring standards. To overcome these limitations, we have redesigned the sampling inlet, the aerodynamic lens, and particle vaporizer. Both the new lens and vaporizer are tested in the lab using a quadruple aerosol mass spectrometer (QAMS) system equipped with light scattering module. Our results show that the capture vaporizer introduces additional thermal decomposition of both inorganic and organic compounds, requiring modifications to the standard AMS fragmentation table, which is used to partition ion fragments to chemical classes. Experiments with mixed NH₄NO₃ and (NH₄)₂SO₄ particles demonstrated linearity in the NH₄⁺ ion balance, suggesting that there is no apparent matrix effect in the thermal vaporization-electron impact ionization detection scheme for mixed inorganic particles. Considering a typical ambient PM_2.5 size distribution, we found that 89% of the non-refractory mass is detected with the new system, while only 65% with the old system. The NR-PM_2.5 system described here can be adapted to existing Aerodyne Aerosol Mass Spectrometer (AMS) and ACSM systems.

Copyright © 2017 American Association for Aerosol Research     

Thermal insulation of buildings in a newly built environment of a hot dry climate: The Saudi Arabian experience

Eight different types of thermal insulation materials were studied and evaluated, with respect to their thermal performance and their impact on space indoor temperature and space cooling and/or heating load in a hot-dry climate context. A predefined computer program, using the transient heat transfer method and thermal response factor method, was utilized as the main research tool for investigation. The study showed significant differences with respect to thermal performance when utilizing different thermal insulation materials of buildings to newly designed and/or retrofitted buildings.

Finally, the study addressed the adoption of thermal insulation in newly-built buildings in the hot dry climate of Saudi Arabia from the viewpoint of the user.     

Speed improvement of multivariate algorithms by the method of postponed basis matrix multiplication. Part III. The use of asymmetric and generalized eigenvalue equations

It is demonstrated that the method for postponed basis matrix multiplication (PBM) applied to principal component analysis can be formulated as asymmetrical and generalized eigenvalue equations.     

Characteristics of a different fuel cycle in a PBMR-400 for burning reactor grade plutonium

An outstanding feature of the high temperature, gas-cooled, version of a Generation IV type reactor is its versatility in application. Apart from the capacity in high temperature gas-cooled reactors to generate electricity it could desalinate (multi-effect distillation [MED] by deploying excess heat or reverse osmosis by deploying excess electricity), produce hydrogen (by deploying excess electricity), whereas this article showcases the on-line fuelling characteristics of a pebble bed reactor concept for the incineration of reactor grade plutonium, whilst producing electricity.The VSOP-A system of codes is employed to demonstrate by calculation how the standard PBMR-400 commercial reactor design offers similar inherent safety characteristics with a Pu-Th/U advanced fuel cycle. This implies that no significant design changes are necessary to implement such a fuel cycle. Furthermore, the flexibility of the pebble fuel concept is deployed to house the fertile material in one type of pebble, whilst a second type will contain the fissile or driver material.     

Development of EPA OTM 10 for Landfill Applications

In 2006, the U.S. Environmental Protection Agency posted a new test method on its website called Other Test Method 10 (OTM 10) which describes direct measurement of pollutant mass emission flux from area sources using ground-based optical remote sensing. The method has validated application to relatively small bounded area sources but additional guidance is needed for large area sources, such as landfills, where the emission zone can exceed the size of optical configuration leading to difficulties in relating measured fluxes to emissions per unit area. This paper presents the findings of a series of tracer-release experiments designed to improve the understanding of OTM 10 in landfill applications. OTM 10 plume capture efficiency data acquired at a variety of landfill sites under a range of meteorological conditions and measurement configurations are presented. Experiments indicate an overall capture efficiency factor of 0.81 with a standard deviation of 0.33. Lower capture efficiencies from side slope releases are noted (0.69). The combined data set is analyzed for factors influencing capture efficiency. A multiple linear regression is used to model the capture efficiency as a function of primary parameters including distance of the tracer release from the observing plane and wind speed. A simplified model based on the regression analysis is described and its use for approximating the area contributing to flux is presented.     

Quantification of abiotic reaction rates in mine tailings: evaluation of treatment methods for eliminating iron- and sulfur-oxidizing bacteria

Effective treatment techniques for eliminating iron-oxidizing (IOB) and sulfur-oxidizing bacteria (SOB) are required for the comparison of abiotic and microbial sulfide oxidation rates and mechanisms in mine tailings. This study evaluates the effect of autoclaving, repeated heating, ethanol treatment, antibiotic treatment, gamma-radiation, and washing with deionized water on tailings characteristics and concentrations of IOB and SOB. Most probable number enumeration indicates that IOB and SOB were present at very low concentrations or below detection limits following treatment with all methods except rinsing and antibiotics treatment, where higher concentrations of IOB and SOB were present. The physical, chemical, and mineralogical characterization of the tailings indicated no changes in bulk mineralogy or bulk chemical composition as a result of treatment. However, an increase in oxidized sulfur species at the tailings surface, as determined by X-ray photoelectron spectroscopy, was observed for the heating, autoclaving, and antibiotics treatments. Batch weathering experiments, used to evaluate the effect of treatment on element release rates, indicated that the final element release rates (after >30 d) were similar between treated and untreated control samples. On the basis of the results of this study, experiments over relatively long periods (>30 d) are to be recommended forthe establishment of microbial and abiotic weathering rates in mill tailings samples. For the determination of abiotic reaction rates, treatment by gamma-radiation is suggested to be the most appropriate method for sulfide-rich tailings.     

Dynamic survival analysis for non-Markovian epidemic models

We present a new method for analysing stochastic epidemic models under minimal assumptions. The method, dubbed dynamic survival analysis (DSA), is based on a simple yet powerful observation, namely that population-level mean-field trajectories described by a system of partial differential equations may also approximate individual-level times of infection and recovery. This idea gives rise to a certain non-Markovian agent-based model and provides an agent-level likelihood function for a random sample of infection and/or recovery times. Extensive numerical analyses on both synthetic and real epidemic data from foot-and-mouth disease in the UK (2001) and COVID-19 in India (2020) show good accuracy and confirm the method’s versatility in likelihood-based parameter estimation. The accompanying software package gives prospective users a practical tool for modelling, analysing and interpreting epidemic data with the help of the DSA approach.