Aerosol

The Increasing pace of Industrialization throughout the world has brought with It a serious, and ever Increasing threat from air pollution. It Is true that this threat Is being taken seriously, and that many responsible research workers, government advisers and others are working towards Its reduction. But air pollution seems to have something of the nature of a hydra-headed monster: tackle one problem and another immediately grows to take its place. Actions taken sometimes have results that are far from what was envisioned, sometimes even seeming to make the problem worse.

In "The Forgotten Pollution", Roos shows clearly and In an often entertaining way, how many of the "unexpected" side effects of pollution by waste gases and particles can be explained by paying attention to the electrical activity of the atmosphere and the earth.
Using an Instrument, which he has developed the Electrostatic Charged Aerosol Monitor (ECAM), together with other instruments and reference to the literature, much of it dating back to the early days of science, when electrostatics was appreciated as a science more than It Is today, Roos has succeeded In explaining many hitherto "puzzling" phenomena in a clear, simple and intellectually satisfying way.

Comparative analysis of salmeterol xinafoate (SX) powders was carried out to define the aerodynamic properties and mechanism of particle dispersion relevant to the use of these materials in dry powder inhalation drug delivery. Particle sizing methodology was evaluated using laser diffraction, time-of-flight and Andersen cascade impactor measurements combined with electron microscopy and surface area determination. Particle interactions, assessed on the basis of powder bulk density and inverse gas chromatography surface energy measurements, were compared with the aerodynamic forces generated by a dry-powder dispersion device. The supercritically produced material showed by a factor of seven reduced tensile strength of the aggregates and indicated a two-fold increase of fine particle fraction deposited in a cascade impactor when blended with lactose. This effect was explained by the reduced particle aggregation at low differential air pressures and flow rates. A relatively small value of aerodynamic stress required to disperse supercritically produced particles in comparison to micronized material comes from: (a) lower bulk density (loose aggregate structure), (b) larger volume mean diameter, (c) larger aerodynamic shape factor and (d) smaller specific free energy of S-SX particles, in this order of priority. It is shown that aggregation between primary drug particles is important for SX/lactose formulations because such aggregates survive the pre-separation impactor stage.

Aerosols consist of two phases: the solid or liquid particles and the gas in which they are suspended. Most of this book deals with the properties and behavior of the aerosol particles, but the suspending gas interacts directly with the particles and has a great effect on their behavior. Particle motion is resisted by the gas, and the nature of this resistance changes with particle size, especially as particle size approaches the spacing between the gas molecules. Aerosol particles share energy with gas molecules and exhibit Brownian motion. Temperature gradients in a gas create a force on an aerosol particle called the thermophoretic force. Because of the varied interactions between a particle and the surrounding gas, we review the properties of gases-particularly, the kinetic theory of gases-before dealing with the properties of aerosols. 2.1 KINETIC THEORY OF GASES To understand the interactions between particles and the suspending gas, it is necessary to consider certain aspects of the kinetic theory of gases. These interactions are described well by the classical kinetic theory of gases, and it is not necessary to consider the more advanced kinctic thcory and quantum mcchanics to get a physical picture of the interactions that is adequate for the study of aerosol properties. According to kinetic theory, the temperature, pressure, mean free path, and viscosity of a gas are manifestations of the motion of the gas molecules. As will be shown, temperature is a measure of the kinetic energy of the molecules, pressure comes from the force of molecular impacts on the container walls, viscosity represents the transfer of momentum by molecular motion, and diffusion is the transfer of molecular mass. The basic assumptions of the kinetic theory are that (I) gases contain a large number of molecules, (2) the molecules are small compared with the distances between them, and (3) the molecules are rigid spheres traveling in straight lines between clastic collisions. Molecules lead a simple, but happy, life in which collisions with other entities arc their only means of expression. Kinetic theory uses this "bil-liard ball" model of gas molecules to describe properties such as temperature, pressure , viscosity, mean free path, diffusion, and thennal conductivity in tenns of the properties of the billiard balls-that is, the number per unit volume 11, mass 171, diameter d m , and velocity c.

The microscopic particles that float in the air are of many kinds: resuspended soil particles, smoke from power generation, photochemically formed particles, salt particles formed from ocean spray  and atmospheric clouds of water droplets or ice particles. However nowadays we have to add the particles coming from large scale forest fires, fires in chemical plants, continuous heavy fog situations, nitrate deposition, and last but not least the COP19 Corona virus outbreak. The combination of these airborne particles and the gas in which they are suspended are called AEROSOLS. Listening to the tsunami of contradictory advises in the case of the virus makes clear that the know how on aerosols is poor or non existent. Therefore the standard book on AEROSOL TECHNOLOGY of Mr. Hinds is proposed here as Teaching Document. It contains highly useful information for all those who never had thought that these virus particles also goes  upwards, that they are able to change their shape in milliseconds from an invisible particle to a fog sized drop. So if you want to understand better how a virus gets into the air, how it is transported there, how it can be killed, but also how it is able to pass masks and filters, how it can be controlled by electrostatics before it is able to reach you through contact or by air. Therefore the governmental instructions: Wash your hands and keep a safety distance with others.

Aerosols consist of two phases: the solid or liquid particles and the gas in which they are suspended. Most of this book deals with the properties and behavior of the aerosol particles, but the suspending gas interacts directly with the particles and has a great effect on their behavior. Particle motion is resisted by the gas, and the nature of this resistance changes with particle size, especially as particle size approaches the spacing between the gas molecules. Aerosol particles share energy with gas molecules and exhibit Brownian motion. Temperature gradients in a gas create a force on an aerosol particle called the thermophoretic force. Because of the varied interactions between a particle and the surrounding gas, we review the properties of gases-particularly, the kinetic theory of gases-before dealing with the properties of aerosols. 2.1 KINETIC THEORY OF GASES To understand the interactions between particles and the suspending gas, it is necessary to consider certain aspects of the kinetic theory of gases. These interactions are described well by the classical kinetic theory of gases, and it is not necessary to consider the more advanced kinctic thcory and quantum mcchanics to get a physical picture of the interactions that is adequate for the study of aerosol properties. According to kinetic theory, the temperature, pressure, mean free path, and viscosity of a gas are manifestations of the motion of the gas molecules. As will be shown, temperature is a measure of the kinetic energy of the molecules, pressure comes from the force of molecular impacts on the container walls, viscosity represents the transfer of momentum by molecular motion, and diffusion is the transfer of molecular mass. The basic assumptions of the kinetic theory are that (I) gases contain a large number of molecules, (2) the molecules are small compared with the distances between them, and (3) the molecules are rigid spheres traveling in straight lines between clastic collisions. Molecules lead a simple, but happy, life in which collisions with other entities arc their only means of expression. Kinetic theory uses this "bil-liard ball" model of gas molecules to describe properties such as temperature, pressure , viscosity, mean free path, diffusion, and thennal conductivity in tenns of the properties of the billiard balls-that is, the number per unit volume 11, mass 171, diameter d m , and velocity c.

Noninvasive ventilation [NIV] is used extensively in acute and chronic settings, at home, and in hospitals. It plays a pivotal role in managing respiratory failure during the COVID-19 pandemic with robust use in hospitals to avert the need for intubation as well as re-intubation. However, its use is associated with aerosol generation, which poses an immediate threat to all who work around it, like healthcare workers. Besides, domiciliary use is also associated with the same risk to the household and caregivers. Therefore, we need to plan the therapy and forge guidelines and recommendations to keep NIV safe during infections. Here we have reviewed the available literature and applied our experience to formulate guidelines and recommendations. However, updates and appraisals are evolving rapidly, and we need to keep our eyes open to tailor our approach.

The air-jet and ball-mill are frequently used in fine micronization of active pharmaceutical ingredients to the order of 1-5 microm, which is important for increasing dissolution rates, and also for pulmonary delivery. In this study, we investigated the ability of air-jet and ball-mill to achieve adequate micronization on the lab scale using a model soft material, Pluronic F-68. Material mechanical properties were characterized using the nanometer 600. Pluronic F-68 was ball-milled in a micro-mill at different material weights and durations in liquid nitrogen vapor. In comparison, a lab scale air-jet mill was used at various milling parameters according to a full factorial design, where the response factors were particle yield and particle size distribution, which was analyzed using laser diffraction and scanning electron microscopy. The yield achieved with the micro-ball mill was 100% but was ~80% for the air-jet mill, which reduced the size of Pluronic F-68 from 70 microm to sizes ranging between 23-39 microm median diameters. Ball milling produced particles less than 10 microm after 15 min. Although air-jet milling proved capable of particle size reduction of the relatively soft material Pluronic F-68, limitations to the lower size range achievable were observed. The feed rate of the material into the air jet mill was a significant factor and slower feed rates lead to smaller sizes by allowing more time for particle collisions and subsequent particle breakage to occur. Micro-ball milling under cold condition was more successful at achieving a lower range particle size reduction of soft materials.

This article may be openly shared  because it is the work created by US government employee, and is considered to be in public domain according to an agreement between Elsevier and the US government. The US government is the copyright owner. The abstract follows: …. A prototype analyzer for the direct LIBS analysis of nebulized liquid samples was developed and tested, particularly for the analysis of petroleum, organic solvents and aqueous solutions. The LIBS analyzer requires about 750 μl of liquid sample, 1 l of N 2 gas, and 10 s of the analysis time to record 100 spectra. The limits of detection in oil and solvent are as low as 0.01-0.04 ppm for Li, Mg, and Cu. They increase for the difficult elements, such as Pb and Hg (7-10 ppm), Cl (250 ppm), and S (~0.7%). The relative standard deviation of measuring 100 ppm vanadium in oil and solvent was 1.5%. The LIBS detection limits and repeatability are better than required by the standard method ASTM D5185 for the analysis of lubricating oils in ICP-OES. Several petroleum samples were analyzed by LIBS and the quantitative results for V, Ni, and Fe compared to the ICP-OES data. Light crude oils can be nebulized and analyzed directly. Medium crude oils may require minimal dilution at least 1:1, otherwise errors of determination may become large. Presumably, utilization of the internal standard and chemometrics can be useful to correct for the matrix effects. In addition to the trace element analysis, the LIBS prototype demonstrated ability to measure the hydrogen-to-carbon ratio in organic liquid samples. Several unidentified features were observed in the carbon spectrum. Their possible origin is discussed. ☆ This article is published in a special honor issue dedicated to Richard E. Russo to commemorate his 70th. birthday, for his achievements in the fields of laser-material interaction, plasma modeling and evolution, surface analysis with lasers, and for his vision of what is needed and critical in future theoretical, instrumental and methodological development.

A transport rno<leÌ for the estimation of tracers spreading from biomass
Ìlrrning areas Ììas been developed on the basis of the semi-Lagrangian technique.
l'hc rnõdel consists of a three-dimerrsional Lagrangian form transport equation for
rracers ancl uses the quasi-rnonotonc locaì cubic-spline interpoÌation for calculation
,rf lnknown values at irregular points. A mass-conserving property of the model is
5asccl on the flux-corrected transport method using the aÌgorithm of Priestley. The
transport of the smoke particles frorn Amazonia was simulated for the period from
August 20 to 29,1995. During tÌris period the air mass iocated below 2 km movecl
to ihe south and carried the smoke particles until 30"S.

The term aerosol, or particulate matter (PM), defines a colloidal mixture where liquid and solid particles are suspended in the air. Aerosols are an integral part of the atmosphere and they therefore interact with solar radiation by affecting climate (primary and secondary effect) and atmospheric visibility. Aerosols also impact human health as they are associated with cardiopulmonary and airways diseases.
This dissertation project focuses on critical aspects of optical particle counters (OPCs), which are based on light scattering to return the particle number concentration and size distribution of airborne aerosol on a real-time basis. The goals of this work are:

1) to characterise and improve the performances of a novel OPC (CompactOPC N1, Alphasense; hereafter COPC) against a standard commercial OPC (Grimm 1.108; hereafter GRM);

2) to build up a test bench for calibrating an OPC used in clean room and sanitary environments (Laser Particle Sensor 3715-00, Kanomax; hereafter LPS). Pollution S.r.l., the Italian producer and distributor of the LPS is keen on this goal, since calibrations of this OPC are not performed in Italy.

Experimental tests were carried out with indoor aerosol and monodisperse spheres of polystyrene latex (PSL) of different sizes, by sampling with all OPCs and, in parallel, onto a filter to count particles at a scanning electron microscope (SEM), in order to obtain an absolute reference value for particle number concentration.
Results indicated a good agreement between the concentrations returned by the GRM and the ones obtained at the SEM. Also, in this work the COPC's performances could be improved by modifying its standard version. Furthermore, the calibration of the LPS could be carried out by using the test bench developed in this work.
The experimental work relating to this dissertation project was carried out in the
Laboratory for Aerosol and Cloud Physics of the Institute for Atmospheric and Climate Science (ISAC) at the Italian National Research Council (CNR) in Bologna.

El objetivo de esta investigación fue identificar los
orígenes de las masas de aire en cuatro ciudades
colombianas (Bogotá, Cartagena de Indias,
Pasto y Leticia) que tienen el potencial de afectar
la calidad del aire urbano al transportar material
particulado a largas distancias desde diferentes
puntos geográficos. Metodológicamente se utilizó
información proporcionada por el modelo HYSPLIT
versión 4, con el cual se midieron retro-trayectorias
para un periodo de análisis de un año
(desde el 01 de enero a 31 de diciembre de 2012).
El cálculo de retrotrayectorias es de gran utilidad
para determinar la zona de partida de las masas
de aire que llegan en un momento determinado,
a un lugar concreto y a una altura definida. De
esta forma se obtuvieron retro-trayectorias diarias
registradas a las 12:00 UTC (tiempo universal
coordinado), con cálculos a intervalos de seis
horas, representando el transporte realizado por
la masa de aire los cinco días anteriores (120 h).
Las alturas isentrópicas consideradas fueron de
750, 1500 y 2500 m medidas desde el nivel del
suelo. Según los resultados obtenidos, el origen
de masas de aire más frecuente en Cartagena
de Indias durante 2012 fue Caribe (45%), seguido
por Continental (36%). En Bogotá fue Continental
(77%), seguido por Atlántico Este (19%). En Pasto
fue Pacífico (72%), seguido por Continental (23%).
Y en Leticia fue Continental (99%) seguido por el
origen Atlántico Este (1%).