Protective Heat (Heat Series Book 3)

Protective Heat Heat Series Book 3 - edelweiss.ml

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Visibility is achieved by making a sharp contrast between the clothing and the background against which it is seen. Protective clothing therefore needs to be chosen according to the predominant background in order to ensure maximum protection. High-visibility clothing generally consists of a basic fluorescent material and a retro-reflective material. The minimum areas in square metres on the background and reflective material determine the class of high-visibility clothing. DIN EN describes the specifications for protective clothing for areas where there is a risk of entanglement in moving parts.

Duly certified protective clothing minimises the risk of entanglement or textiles getting caught in moving parts if the wearer is working at or near machinery or equipment with dangerous movements. Test method for measuring surface resistivity Part 2: Test method for measuring vertical resistance Part 3: Test method for measuring charge decay Part 4: Testing clothing standard currently in progress Part 5: Performance requirements for material and construction This is protective clothing with antistatic characteristics.

This clothing reduces electrostatic charging of personnel and the occurrence of inflammable static sparks.

Introduction

It is required in areas where explosive atmospheres can occur. The standard defines the electrostatic requirements for clothing to avoid inflammable discharges. Protective clothing for welding and allied processes in accordance with EN ISO protects the wearer from small molten metal splashes, brief contact with flames, and radiant heat from the electrical arc. The clothing can be suitable for persons during welding and allied processes where the same type and similar hazards occur. The protective effect is achieved with flame retardant fabric in conjunction with specific processing properties, which are defined in EN ISO One criterion for classification as protective clothing for use in welding is limited flame spread.

Testing this criterion involves analysing how the fabric burns after being exposed to a small vertical flame. Method A — surface ignition: The flame is applied to the centre of the sample. Method B — bottom edge ignition: The flame is applied to the bottom edge of the sample. Protective clothing of standard EN ISO — clothing to protect against heat and flames — protects workers who come into brief contact with flames and at least a type of heat.

A test criterion for classification as protective clothing for workers exposed to heat is the limited flame spread in accordance with EN ISO previously DIN EN , in the same way as the test criterion for protective clothing for use in welding code letter A. The type of heat is defined by the codes B to F. The heat that occurs can be convective code letter B , radiant code letter C , caused by molten aluminium code letter D or molten iron code letter E splashes, as contact heat code letter F or as a combination of these forms.

In addition to the code letters, performance levels 1 to 4 are also specified for this protective clothing.

Protective clothing and disposable coveralls

The higher the performance levels, the higher the protective effect of the relevant item. The protective effect is achieved with flame-retardant fabric in conjunction with specific processing properties. Additional performance levels are defined for heat transfer:. The full clothing can be optionally tested to predict burns. Protective clothing in accordance with the DIN EN standard — protective clothing against the thermal risks of an electric arc — refers to thermal clothing.

This clothing is suitable for work in the low-voltage range where thermal risks can occur because of an electric arc. The measurement is taken using the CENELEC arc box test in which energetic thermal insulation measurements and a quantitative evaluation of the burn risk are carried out. The clothing is not, however, electrically insulating protective clothing in accordance with EN If the front of the product in the case of jackets for example is in a higher protection class than the back, the entire front, including the sleeves, must be in this higher class.

The different performance of the back must be clearly marked. The standard aims to prevent potential hazards from inadvertent, brief and occasional contact with small flames. This relates to situations where there are no significant risks from heat or any other heat sources. Protective clothing that complies with this standard is not suitable if additional protection is needed because of a risk from heat and flames.

The standard also defines additional requirements for protective clothing, including mechanical requirements and requirements governing labeling and the supply of information from the manufacturer. Protective clothing in accordance with EN ISO consists of several one or multi-layered garments or a single garment. Each material assembly is assigned to an index 1, 2 or 3 for limited flame spread in accordance with testing as per ISO DIN EN certified products.

In summary, in the present study, we continuously observed the microcirculation in the spinotrapezius of rats with severe heat shock and measured the total SOD activity and ROS level changes. The findings revealed the changes in the oxidative stress levels in local tissues during heat stress, showed an association between the changes in the microcirculatory blood flow volume and those in the systemic circulatory blood flow volume, and demonstrated that a gradual decrease in SOD in local rat tissues could result in increased ROS levels, which in turn induced microcirculation disturbances.

The microcirculation disturbances occurred before systemic circulation disturbances and could be an important factor causing circulatory failure after severe heat shock.

Xuebijing reduced the local ROS level and protected the microcirculation during heat stress, thus improving the prognosis of rats with severe heat shock. Standard food and water were provided to the rats during the study.

Forty of the rats were divided into 4 groups 10 in each group as follows: All the rats except for those in the control group were placed in an infant incubator for heat stress exposure. The 27 rats were divided into 3 groups as follows: In each group, the rats were further divided into three subgroups as follows: This study was approved by the Animal Ethics Committee of Southern Medical University and conducted according to the guidelines and regulations for the use and care of experimental animals in China.

In addition, this study also minimized the number of animals and the discomfort of the animals, according to the guidelines for experiments with living animals in China. The SOD inhibitory rate was calculated using the following equation:. The weight of the spinotrapezius muscle was accurately measured. Part of the supernatant was used to determine the protein concentration by the BCA method. A flow cytometer was used to analyze ROS levels. Preparation of the spinotrapezius muscle and intravital microscopy: The spinotrapezius muscles are located anatomically in the mid-dorsal region, originating in the lower thoracic and upper lumbar regions and inserted at the scapular spine.

Microcirculatory Disorders and Protective Role of Xuebijing in Severe Heat Stroke

Spinotrapezius muscles were prepared as previously described by Gray Briefly, the spinotrapezius muscle was exteriorized with marginal damage to the fascia. No evidence of local trauma, which might impact regional blood flow in this model, was reported. The solution was heated to prevent loss of heat via perfusion. The exposed spinotrapezius muscle was fixed at six equidistant sites around the caudal periphery to ensure consistent shape and length of the selected vessels.

Assuming cylindrical geometry, the blood flow rate was calculated using the following formula: The prepared spinotrapezius muscle was covered with thin gauze, which was continuously perfused with a heated Krebs—Henseleit bicarbonate-buffered solution. Then, right femoral artery catheterization was performed. SOD and Xuebijing were injected accordingly as described earlier. One hour later, the rats were placed in an infant incubator for heat stress exposure, and the microcirculation was observed by intra vital microscopy. Since the rats had to be removed from the infant incubator at each time point, the microcirculation observation was conducted as fast as possible to avoid allowing the core temperature of the rats to drop Fig.

Experimental protocol and outline. Surgery included spinotrapezius preparation and right femoral artery catheterization.

Standards and Directives

The microcirculation was observed by intravital microscopy. All rats were kept in an infant incubator for heat stress environmental temperature: The change of weight was calculated as follows: Analysis of variance for repeated measurements was used to compare the differences between groups at different time points.

Pair wise comparisons were conducted using t tests. Jiang conceived and designed the experiments; H. Jin performed the experiments; H. Chen analyzed the data; H. Jin wrote the manuscript; and L. Su reviewed the manuscript and supervised the research. All authors read and approved the final manuscript. Hui Jin and Yi Chen contributed equally to this work. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. National Center for Biotechnology Information , U. Published online Mar Author information Article notes Copyright and License information Disclaimer.

Received Sep 7; Accepted Mar 1. To view a copy of this license, visit http: Abstract This study was conducted to explore underlying mechanism of microcirculation dysfunction and protectiverole of Xuebijing in heat stroke.

Introduction Despite several decades of studies, heat stroke remains a major clinical problem with high morbidity and mortality and a high incidence of multiple organ dysfunction syndromes MODS. Results Changes of SOD activity in spinotrapezius tissue homogenates during heat stress SOD activity decreased gradually with the increase in the core temperature during heat stress compared with the control group.

Open in a separate window. Discussion Heat stroke can be classified as classic heat stroke or exertional heat stroke according to the etiology 4. Table 1 Grouping and number of animals for microcirculatory observation. The SOD inhibitory rate was calculated using the following equation: Measuring the ROS level in the spinotrapezius The weight of the spinotrapezius muscle was accurately measured. Microcirculation monitoring Preparation of the spinotrapezius muscle and intravital microscopy: Notes Competing Interests The authors declare no competing interests.

Footnotes Hui Jin and Yi Chen contributed equally to this work. Contributor Information Dongxin Jiang, Email: Semenza JC, et al. Heat-related deaths during the July heat wave in Chicago. A heat shield is a part of an object designed to protect the object from overheating by dissipating, reflecting or simply absorbing the heat. The term is most often used in reference to exhaust heat management and to systems for dissipation of heat due to friction. Due to the large amounts of heat given off by internal combustion engines, heat shields are used on most engines to protect components and bodywork from heat damage.

As well as protection, effective heat shields can give a performance benefit by reducing the under-bonnet temperatures, therefore reducing the intake temperature. Heat shields vary widely in price, but most are easy to fit, usually by stainless steel clips or high temperature tape. There are two main types of automotive heat shield:. As a result, a heat shield is often fitted by both amateur and professional personnel during a phase of engine tuning.

Heat shields are also used to cool engine mount vents.

About testing procedures and fulfilling safety standards

When a vehicle is at higher speed there is enough ram air to cool the under hood engine compartment, but when the vehicle is moving at lower speeds or climbing a gradient there is a need of insulating the engine heat to get transferred to other parts around it, e. With the help of proper thermal analysis and use of heat shields, the engine mount vents can be optimised for the best performances. Some aircraft at high speed, such as the Concorde and SR Blackbird , must be designed considering similar, but lower, overheating to what occurs in spacecraft.

Recently new materials have been developed that could be superior to '' RCC. They are also structurally more resistant than RCC, so they do not require additional reinforcements, and are very efficient in re-irradiating the absorbed heat. NASA funded and subsequently discontinued a research and development program in for testing this protection system through the University of Montana. The European Commission funded a research project, C3HARME, under the NMP call of Framework Programmes for Research and Technological Development in still ongoing for the design, development, production and testing of a new class of ultra-refractory ceramic matrix composites reinforced with silicon carbide fibers and Carbon fibers suitable for applications in severe aerospace environments.

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