scholarly journals CONCENTRATION AND SIZE OF AIRBORNE PARTICLES IN MANUFACTURING ENVIRONMENTS

2018 ◽  
Vol 42 (1) ◽  
Author(s):  
Renilson Luiz Teixeira ◽  
Raphael Nogueira Rezende ◽  
José Reinaldo Moreira da Silva ◽  
Luana Elís de Ramos e Paula
Keyword(s):  
Medium Density Fiberboard ◽  
Work Environments ◽  
Airborne Particles ◽  
Protective Equipment ◽  
Particle Sizes ◽  
Small Particles ◽  
Measuring Process ◽  
Minas Gerais State ◽  
High Concentrations ◽  
Manufacturing Environments

ABSTRACT In furniture factories, the cutting of medium density fiberboard (MDF) generates high concentrations of particulates suspended in the air, which, depending on their dimensions, can reach the sensitive areas of the respiratory tract of workers. The aim of this study was to test a method to measure particle sizes derived from the cutting of wood paneling. The experiment was conducted in two small furniture factories located in the municipality of Lavras, Minas Gerais state, Brazil. During the cutting of MDF, airborne particles were collected and measured by means of optical microscopy. The data obtained showed a critical condition in the work environments, with high concentrations of small particles (<10 microns), which could be lodged in the workers’ lungs. The particle measuring process proved to be accurate and easy to perform. In addition, it is worth noting the importance of investment in personal protective equipment (PPE) such as hoods and/ or PFF2 dust masks for the protection of workers.

Ensuring safety at industrial enterprises with the help of personal protective equipment

2021 ◽  
pp. 49-53
Author(s):  
Mats Friberg
Keyword(s):  
Personal Protective Equipment ◽  
Airborne Particles ◽  
Protective Equipment ◽  
Respiratory Protection ◽  
Biological Origin ◽  
Industrial Enterprises ◽  
Risk Of Exposure ◽  
High Concentrations

During events that threaten people's health, high concentrations of pollutants in the air, outbreaks of diseases transmitted by airborne droplets, special filtering means of protection are used. If used correctly, respirators can reduce the risk of exposure to airborne particles, including aerosols of biological and non-biological origin. Mats Friberg tells about what you should pay attention to when choosing respiratory protection products and how to use them correctly.

RESEARCH: Dry Heat Processing of Single-Use Respirators and Surgical Masks

2020 ◽  
Vol 54 (6) ◽  
pp. 410-416
Author(s):  
Joyce M. Hansen ◽  
Scott Weiss ◽  
Terra A. Kremer ◽  
Myrelis Aguilar ◽  
Gerald McDonnell
Keyword(s):  
Microbial Contamination ◽  
Healthcare Providers ◽  
High Volume ◽  
Airborne Particles ◽  
Heat Processing ◽  
Protective Equipment ◽  
Healthcare Facilities ◽  
Dry Heat ◽  
Surgical Masks ◽  
Single Use

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2, has challenged healthcare providers in maintaining the supply of critical personal protective equipment, including single-use respirators and surgical masks. Single-use respirators and surgical masks can reduce risks from the inhalation of airborne particles and microbial contamination. The recent high-volume demand for single-use respirators and surgical masks has resulted in many healthcare facilities considering processing to address critical shortages. The dry heat process of 80°C (176°F) for two hours (120 min) has been confirmed to be an appropriate method for single-use respirator and surgical mask processing.

Particle regularity on thylakoid fracture faces is influenced by storage conditions

1995 ◽  
Vol 73 (10) ◽  
pp. 1676-1682 ◽  
Author(s):  
Galina A. Semenova
Keyword(s):  
Particle Density ◽  
Freeze Fracture ◽  
Storage Conditions ◽  
Medium Composition ◽  
Prolonged Storage ◽  
Particle Sizes ◽  
Fracture Face ◽  
Small Particles ◽  
Mean Size ◽  
Regular Arrays

Specific temperature, storage times, and medium composition enable initiation of regular arrays of intramembranous particles on the exoplasmic fracture face during prolonged storage of isolated chloroplasts at 4 °C, producing about 2 – 10 regular arrays with 2 – 30 particles in each array, with a period of about 36 nm, oriented in 1 – 4 directions. The particle sizes do not change throughout the time of storage (1 – 4 weeks). The second type of particle regularity arises during prolonged storage of chloroplasts in greater than 1 M sucrose at −18 °C. Rounded areas of small particles tightly packed into paracrystalline arrays are found among less densely packed particles. The density of small particles is 4700 particles/μm2, and the mean size is 11 nm, whereas the particle density of the background is 1600 particles/μm2 with a mean particle size of 13 nm compared with 1200 particles/μm2 and mean size 16 nm in fresh chloroplasts. Based on the reduction of particle sizes and manner of packing on the fracture face, it is proposed that the small particles are a light-harvesting complex, separate from photosystem II and aggregated into paracrystalline arrays. The thylakoid lipids may participate in formation of particle regularity. Key words: thylakoid membrane, freeze fracture, particle regularity, low temperatures.

scholarly journals Modeling the dynamical sinking of biogenic particles in oceanic flow

2017 ◽  
Vol 24 (2) ◽  
pp. 293-305 ◽  
Author(s):  
Pedro Monroy ◽  
Emilio Hernández-García ◽  
Vincent Rossi ◽  
Cristóbal López
Keyword(s):  
Three Dimensional ◽  
Finite Size ◽  
Equation Of Motion ◽  
Particle Dynamics ◽  
Particle Sizes ◽  
Small Particles ◽  
Physical Processes ◽  
Mesoscale Simulation ◽  
Sinking Particles ◽  
Theoretical Results

Abstract. We study the problem of sinking particles in a realistic oceanic flow, with major energetic structures in the mesoscale, focussing on the range of particle sizes and densities appropriate for marine biogenic particles. Our aim is to evaluate the relevance of theoretical results of finite size particle dynamics in their applications in the oceanographic context. By using a simplified equation of motion of small particles in a mesoscale simulation of the oceanic velocity field, we estimate the influence of physical processes such as the Coriolis force and the inertia of the particles, and we conclude that they represent negligible corrections to the most important terms, which are passive motion with the velocity of the flow, and a constant added vertical velocity due to gravity. Even if within this approximation three-dimensional clustering of particles can not occur, two-dimensional cuts or projections of the evolving three-dimensional density can display inhomogeneities similar to the ones observed in sinking ocean particles.

scholarly journals Biogenic amines formation and their importance in fermented foods

2020 ◽  
Vol 17 ◽  
pp. 00232
Author(s):  
Kamil Ekici ◽  
Abdullah Khalid Omer
Keyword(s):  
Amino Acid ◽  
Biogenic Amines ◽  
Raw Material ◽  
Health Concern ◽  
Fermented Foods ◽  
Organic Bases ◽  
Food Borne ◽  
High Concentrations ◽  
Amino Acid Precursors ◽  
Manufacturing Environments

Biogenic amines (BAs) are low molecular weight organic bases with an aliphatic, aromatic, or heterocyclic structure which have been found in many foods. biogenic amines have been related with several outbreaks of food-borne intoxication and are very important in public health concern because of their potential toxic effects. The accumulation of biogenic amines in foods is mainly due to the presence of bacteria able to decarboxylate certain amino acids. Biogenic amines are formed when the alpha carboxvl group breaks away from free amino acid precursors. They are colled after the amino acid they originated from. The main biogenic amines producers in foods are Gram positive bacteria and cheese is among the most commonly implicated foods associated with biogenic amines poisoning. The consumption of foods containing high concentrations of biogenic amines has been associated with health hazards and they are used as a quality indicator that shows the degree of spoilage, use of non-hygienic raw material and poor manufacturing practice. Biogenic amines may also be considered as carcinogens because they are able to react with nitrites to form potentially carcinogenic nitrosamines. Generally, biogenic amines in foods can be controlled by strict use of good hygiene in both raw material and manufacturing environments with corresponding inhibition of spoiling microorganisms. The aim of this review was to give some information about biogenic amines in foods.

scholarly journals Dissolution of Lipid-Based Matrices in Simulated Gastrointestinal Solutions to Evaluate Their Potential for the Encapsulation of Bioactive Ingredients for Foods

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Yves Raymond ◽  
Claude P. Champagne
Keyword(s):  
Cocoa Butter ◽  
Functional Foods ◽  
Palm Kernel ◽  
Probiotic Bacteria ◽  
Particle Sizes ◽  
Small Particles ◽  
Carnauba Wax ◽  
Kernel Oil ◽  
Bioactive Ingredients ◽  
Gastric Secretions

The goal of the study was to compare the dissolution of chocolate to other lipid-based matrices suitable for the microencapsulation of bioactive ingredients in simulated gastrointestinal solutions. Particles having approximately 750 μm or 2.5 mm were prepared from the following lipid-based matrices: cocoa butter, fractionated palm kernel oil (FPKO), chocolate, beeswax, carnauba wax, and paraffin. They were added to solutions designed to simulate gastric secretions (GS) or duodenum secretions (DS) at 37°C. Paraffin, carnauba wax, and bees wax did not dissolve in either the GS or DS media. Cocoa butter, FPKO, and chocolate dissolved in the DS medium. Cocoa butter, and to a lesser extent chocolate, also dissolved in the GS medium. With chocolate, dissolution was twice as fast as that with small particles (750 μm) as compared to the larger (2.5 mm) ones. With 750 μm particle sizes, 90% dissolution of chocolate beads was attained after only 60 minutes in the DS medium, while it took 120 minutes for 70% of FPKO beads to dissolve in the same conditions. The data are discussed from the perspective of controlled release in the gastrointestinal tract of encapsulated ingredients (minerals, oils, probiotic bacteria, enzymes, vitamins, and peptides) used in the development of functional foods.

scholarly journals Shattering during Sampling by OAPs and HVPS. Part I: Snow Particles

2005 ◽  
Vol 22 (5) ◽  
pp. 528-542 ◽  
Author(s):  
Alexei Korolev ◽  
George A. Isaac
Keyword(s):  
Remote Sensing ◽  
Wind Shear ◽  
High Volume ◽  
Sample Volume ◽  
Particle Sizes ◽  
Small Particles ◽  
Cloud Particle ◽  
Ice Particles ◽  
Imaging Probes ◽  
Cloud Parameterization

Abstract The data on cloud particle sizes and concentrations collected with the help of aircraft imaging probes [optical array probes OAP-2DC, OAP-2DP, and the High Volume Precipitation Spectrometer (HVPS)] are widely used for cloud parameterization and validation of remote sensing. The goal of the present work is to study the effect of shattering of ice particles during sampling. The shattering of ice particles may occur due to 1) mechanical impact with the probe arms prior to their entering the sample volume, and 2) fragmentation due to interaction with turbulence and wind shear generated by the probe housing. The effect of shattering is characterized by the shattering efficiency that is equal to the ratio of counts of disintegrated particles, to all counts. The shattering efficiency depends on the habit, size, and density of ice particles, probe inlet design, and airspeed. For the case of aggregates, the shattering efficiency may reach 10% or even more. The shattering of ice particles results in an overcounting of small particles and an undercounting of large ones. The number of fragments in the images of shattered particles may reach several hundreds. It was found that particles as small as 600 μm may shatter after impact with the probe arms. The effect of particle shattering should be taken into account during data analysis and carefully considered in future designs of airborne cloud particle size spectrometers.

Multivariate modeling of MDF panel properties in relation to wood fiber characteristics

Holzforschung ◽  
2006 ◽  
Vol 60 (3) ◽  
pp. 285-293 ◽  
Author(s):  
Jun Li Shi ◽  
S.Y. Zhang ◽  
Bernard Riedl
Keyword(s):  
Wood Density ◽  
Medium Density Fiberboard ◽  
Wood Fiber ◽  
Arithmetic Mean ◽  
Modulus Of Rupture ◽  
Predictor Variables ◽  
Small Particles ◽  
Dummy Variables ◽  
Functional Relationships ◽  
Response Variables

Abstract Properties of medium density fiberboard (MDF) panels in relation to wood and fiber characteristics were investigated. Laboratory MDF panels were manufactured from raw fiber materials from black spruce [Picea mariana (Mill.) BSP.], three hybrid poplar clones (Populus spp.), two exotic larch (Larix gmelinii and Larix sibirica), and a mix of spruce, pine, and fir wood chips. The panels were evaluated for modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), linear expansion (LE), thickness swelling (TS), and water absorption (WA). These properties were analyzed as response variables. As predictor variables, various wood and fiber characteristics were measured, including wood density, pH, base buffering capacity and fiber coarseness. Multiple linear regression analysis was performed to develop functional relationships between panel properties (response variables) and wood fiber characteristics (predictor variables). Ten dummy variables were created and incorporated into the analysis to examine the effects of wood species or type on MDF panel properties. MOR was negatively related to arithmetic fine percentage. MOE was negatively affected by the percentage of small particles (>200 mesh) and wood pH. IB strength was negatively related to arithmetic fine percentage and fiber pH, but positively related to the percentage of small particles (>200 mesh). Wood density affected LE. TS was negatively affected by arithmetic mean fiber length. Arithmetic mean fiber width had a negative effect on panel WA. The presence of dummy variables in the models for MOE, IB and LE indicates that wood fiber characteristics other than those measured in this study significantly affected these panel properties. The study indicates that the refining process can play a significant role in manipulating MDF panel properties.

Reduction of Turbidity of Beet Sugar Solutions by Mechanical and Chemical Treatment

2015 ◽  
Vol 11 (1) ◽  
pp. 41-49 ◽  
Author(s):  
El-Sayed Ali Abdel-Rahman ◽  
Eckhard Floeter
Keyword(s):  
Sodium Carbonate ◽  
Calcium Concentration ◽  
Particle Sizes ◽  
Small Particles ◽  
Cation Exchangers ◽  
Thick Juice ◽  
Intermediate Storage ◽  
Industrial Level ◽  
Filter Aids ◽  
Reference Samples

Abstract The presence of practically non-dissolvable small particles in sugar solutions can cause haze during application and has to be minimal. Intermediate storage of thick sugar juice becomes increasingly common practice. In particular juices treated with anti-scale agents appear to be prone to turbidity development. This work on turbidity mitigation reports results on both laboratory and industrial level experiments. Different filter aids were tested and led to reduced turbidity levels. At industrial and lab scale reductions in the order of 30–54% and 50–70% were achieved respectively, which however remains insufficient to resolve the problem. The chemical mitigation by reduction of the hardness of the juice either by sodium carbonate or by ion exchanger treatment was investigated. While the reduction of the calcium concentration by dosing of sodium carbonate turned out to be basically possible, this remains less practical than the utilization of cation exchangers. Furthermore, it was found that application of anti-scale agents causes a reduction on the particle sizes that are found in thick juice samples after 2 months storage. Turbidity values of these samples were, independent of dosage and type of anti-scale agent, twice as high as in reference samples.

scholarly journals The Cupola: An Additional Layer of Protection for Providers Working in the Oropharyngeal Region

2021 ◽  
Author(s):  
Alessandro Villa ◽  
Marlene Grenon
Keyword(s):  
Pilot Study ◽  
Personal Protective Equipment ◽  
Airborne Particles ◽  
Protective Equipment ◽  
Additional Layer ◽  
Dental Procedures ◽  
The Mean ◽  
Mechanical Barrier

Abstract ObjectivesTo reduce the spread of the infection, especially during aerosol generating procedures, we invented “The Cupola”, a shield that creates a mechanical barrier around the patient’s head and body. With this pilot study we aimed to assess the effectiveness of an additional layer of protection (The Cupola) developed for providers working in the oropharyngeal region.ResultsThe mean number of 0.3 μm particles with no Cupola was 3777 (SD: ±556), with The Cupola was 2068 (SD: ±1468) and with the Cupola and Drape was 2031 (SD: ±1108) (p<0.015). The mean number of 0.5 μm airborne particles with no Cupola was 65 (SD: ±7), with The Cupola was 29 (SD: ±28) and with the Cupola and Drape was 28 (SD: ±23) (p<0.05). Results showed a significant reduction of aerosols generated during simulated dental procedures when the Cupola was used. The Cupola offers an extra layer of protection in addition to the recommended personal protective equipment.

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