The Heat Stress Effects on the Gases Permeability of the Isolative Type Garment of the Czech Armed Forces Chemical Corps Specialists Body Surface Protection

2019 ◽  
Vol 70 (5) ◽  
pp. 1597-1602
Author(s):  
Pavel Otrisal ◽  
Karel Friess ◽  
Lucia Feherova ◽  
Zdenek Melicharik ◽  
Lubomir Svorc ◽  
...  
Keyword(s):  
Body Surface ◽  
Structural Changes ◽  
Armed Forces ◽  
Gas Permeation ◽  
Scanning Calorimetry ◽  
Surface Protection ◽  
Barrier Materials ◽  
Stress Effects ◽  
Optical Profilometer ◽  
Materials Used

In our research, both theoretical and practical approaches to the assessment of permeability of barrier materials used to produce protective garments of an isolative type designed for body surface protection have been studied. The main goal of this paper is to study the thermal resistance for a barrier material of the ventilated anti-gas isolative garment OPCH-05 which is used in the conditions of the Czech Armed Forces for the Chemical Corps specialists� protection against the effects of toxic compounds. The thermal analysis of samples was performed using the differential scanning calorimetry, the surface structural changes were determined via the 3D optical profilometer and the gas permeation measurements were performed by means of the integral permeation method. Based on permeation results, the appropriate time limits and the temperatures of the exposure, during which the chemical protective garment could be securely used, were evaluated.

Specification of Destructive Influences of Selected Decontamination Mixtures on Materials Used for Construction of Chemical Specialists´ Garments Designated for Isolative Protection of the Body Surface

2018 ◽  
Vol 24 (3) ◽  
pp. 138-145
Author(s):  
Zdeněk Melichařík ◽  
Pavel Otřísal
Keyword(s):  
Body Surface ◽  
Armed Forces ◽  
Selective Decontamination ◽  
Butyl Rubber ◽  
The Body ◽  
Effective Protection ◽  
Materials Used ◽  
Protective Garment ◽  
Repeated Contact

Abstract A paper deals with the influence of selective decontamination mixtures established in the Czech Armed Forces on an isolative protective foil used to the construction of anti-gas protective garment marked as OPCH-05. Presented information are a part of thematically focused works aimed to study of influences of all established decontamination mixtures on the Czech Armed Forces Chemical Corps´ garments of anti-gas protection. The quality of provided the Czech Armed Forces Chemical Corps´ specialists isolative protection is limited with the existence of several aspects which significantly determine with their materials equipment. For providing isolative protection of the body surface are used such as protective garments which are the hermetic type and they are constructively solved with the employment of the butyl-rubber polymeric mixture. The effective protection of the body surface must be guaranteed even within the presumption of a repeated contact with decontamination mixtures

scholarly journals Assessment of Chemical Resistance of Barrier Materials based on Practical Application of Conductometry

2016 ◽  
Vol 22 (3) ◽  
pp. 662-669
Author(s):  
Pavel Otřísal ◽  
Stanislav Florus
Keyword(s):  
Relative Permittivity ◽  
Temperature Compensation ◽  
Chemical Resistance ◽  
Armed Forces ◽  
Carbon Electrodes ◽  
Practical Application ◽  
Barrier Materials ◽  
Theoretical Approaches ◽  
High Relative Permittivity ◽  
Materials Used

Abstract A paper deals with basic theoretical approaches for conductometry employment and its possibilities within testing chemical resistance of barrier materials. A classical conductometry is one from the oldest electro-analytical methods which deals with a measurement of conductivity of solution in water or even another solvent with high relative permittivity when comes to dissociation of an electrolyte on ions. Within employment of conductometric test for evaluation of chemical resistance of barrier materials used in anti-gas protection of the Czech Armed Forces Chemical Corps specialists based theoretical principles have been used. Their application, however, have reached a certain degree of rationalization such as the employment of special carbon electrodes, ensuring temperature compensation within performing long measurements and ensuring mixture of the electrolyte.

scholarly journals The Influence of Decontamination Mixture of ODS-4 on Chemical Resistance of the Garments for Body Surface Isolative Protection of the Czech Armed Forces Chemical Corps Specialists

2016 ◽  
Vol 22 (3) ◽  
pp. 654-661
Author(s):  
Zdeněk Melichařík ◽  
Pavel Otřísal ◽  
Stanislav Florus
Keyword(s):  
Body Surface ◽  
Chemical Resistance ◽  
Armed Forces ◽  
Butyl Rubber ◽  
Effective Protection ◽  
Current Time ◽  
Surface Protection ◽  
Protective Garment

Abstract Providing effective isolative protection of the Czech Armed Forces Chemical Corps’ specialist is long-term, developed and perspective problems. In current time established protective garments designated for hermetical body surface protection of the Czech Armed Forces Chemical Corps’ specialist are constructively solved with the employment of a mixture based on a butyl-rubber polymeric mixture both-sided coated on a polymeric fabric. Effective protection of a body surface has to be guaranteed for the whole time of usage of a protective garment, thus after performed repeated decontamination. The paper deals with influences of decontamination mixtures ODS-4 on the isolative protective foil used for production of anti-gas protective garment marked as OPCH-05 which is established as the garment for specialists’ body surface protection.

scholarly journals Dynamic Single-Fiber Pull-Out of Polypropylene Fibers Produced with Different Mechanical and Surface Properties for Concrete Reinforcement

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 722
Author(s):  
Enrico Wölfel ◽  
Harald Brünig ◽  
Iurie Curosu ◽  
Viktor Mechtcherine ◽  
Christina Scheffler
Keyword(s):  
Tensile Strength ◽  
Dynamic Loading ◽  
Melt Spinning ◽  
Structural Changes ◽  
High Surface ◽  
Single Fiber ◽  
Scanning Calorimetry ◽  
Matrix Interaction ◽  
Pull Out ◽  
Fiber Matrix

In strain-hardening cement-based composites (SHCC), polypropylene (PP) fibers are often used to provide ductility through micro crack-bridging, in particular when subjected to high loading rates. For the purposeful material design of SHCC, fundamental research is required to understand the failure mechanisms depending on the mechanical properties of the fibers and the fiber–matrix interaction. Hence, PP fibers with diameters between 10 and 30 µm, differing tensile strength levels and Young’s moduli, but also circular and trilobal cross-sections were produced using melt-spinning equipment. The structural changes induced by the drawing parameters during the spinning process and surface modification by sizing were assessed in single-fiber tensile experiments and differential scanning calorimetry (DSC) of the fiber material. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurements were applied to determine the topographical and wetting properties of the fiber surface. The fiber–matrix interaction under quasi-static and dynamic loading was studied in single-fiber pull-out experiments (SFPO). The main findings of microscale characterization showed that increased fiber tensile strength in combination with enhanced mechanical interlocking caused by high surface roughness led to improved energy absorption under dynamic loading. Further enhancement could be observed in the change from a circular to a trilobal fiber cross-section.

scholarly journals Comparative Study of Structural Changes of Polylactide and Poly(ethylene terephthalate) in the Presence of Trichoderma viride

2021 ◽  
Vol 22 (7) ◽  
pp. 3491
Author(s):  
Grażyna B. Dąbrowska ◽  
Zuzanna Garstecka ◽  
Ewa Olewnik-Kruszkowska ◽  
Grażyna Szczepańska ◽  
Maciej Ostrowski ◽  
...  
Keyword(s):  
Structural Changes ◽  
Ethylene Terephthalate ◽  
Molecular Mechanisms ◽  
Blot Hybridization ◽  
Trichoderma Viride ◽  
Cost Effective ◽  
Plastic Pollution ◽  
Scanning Calorimetry ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene

Plastic pollution is one of the crucial global challenges nowadays, and biodegradation is a promising approach to manage plastic waste in an environment-friendly and cost-effective way. In this study we identified the strain of fungus Trichoderma viride GZ1, which was characterized by particularly high pectinolytic activity. Using differential scanning calorimetry, Fourier-transform infrared spectroscopy techniques, and viscosity measurements we showed that three-month incubation of polylactide and polyethylene terephthalate in the presence of the fungus lead to significant changes of the surface of polylactide. Further, to gain insight into molecular mechanisms underneath the biodegradation process, western blot hybridization was used to show that in the presence of poly(ethylene terephthalate) (PET) in laboratory conditions the fungus produced hydrophobin proteins. The mycelium adhered to the plastic surface, which was confirmed by scanning electron microscopy, possibly due to the presence of hydrophobins. Further, using atomic force microscopy we demonstrated for the first time the formation of hydrophobin film on the surface of aliphatic polylactide (PLA) and PET by T. viride GZ1. This is the first stage of research that will be continued under environmental conditions, potentially leading to a practical application.

scholarly journals Metastable Intermediates as Stepping Stones on the Maturation Pathways of Viral Capsids

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Giovanni Cardone ◽  
Robert L. Duda ◽  
Naiqian Cheng ◽  
Lili You ◽  
James F. Conway ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Large Scale ◽  
Structural Changes ◽  
Energy Landscape ◽  
Potential Hazard ◽  
Stepping Stones ◽  
Scanning Calorimetry ◽  
Conformational Effects ◽  
Capsid Maturation ◽  
Capsid Integrity

ABSTRACT As they mature, many capsids undergo massive conformational changes that transform their stability, reactivity, and capacity for DNA. In some cases, maturation proceeds via one or more intermediate states. These structures represent local minima in a rich energy landscape that combines contributions from subunit folding, association of subunits into capsomers, and intercapsomer interactions. We have used scanning calorimetry and cryo-electron microscopy to explore the range of capsid conformations accessible to bacteriophage HK97. To separate conformational effects from those associated with covalent cross-linking (a stabilization mechanism of HK97), a cross-link-incompetent mutant was used. The mature capsid Head I undergoes an endothermic phase transition at 60°C in which it shrinks by 7%, primarily through changes in its hexamer conformation. The transition is reversible, with a half-life of ~3 min; however, >50% of reverted capsids are severely distorted or ruptured. This observation implies that such damage is a potential hazard of large-scale structural changes such as those involved in maturation. Assuming that the risk is lower for smaller changes, this suggests a rationalization for the existence of metastable intermediates: that they serve as stepping stones that preserve capsid integrity as it switches between the radically different conformations of its precursor and mature states. IMPORTANCE Large-scale conformational changes are widespread in virus maturation and infection processes. These changes are accompanied by the release of conformational free energy as the virion (or fusogenic glycoprotein) switches from a precursor state to its mature state. Each state corresponds to a local minimum in an energy landscape. The conformational changes in capsid maturation are so radical that the question arises of how maturing capsids avoid being torn apart. Offering proof of principle, severe damage is inflicted when a bacteriophage HK97 capsid reverts from the (nonphysiological) state that it enters when heated past 60°C. We suggest that capsid proteins have been selected in part by the criterion of being able to avoid sustaining collateral damage as they mature. One way of achieving this—as with the HK97 capsid—involves breaking the overall transition down into several smaller steps in which the risk of damage is reduced.

Thermo-Optical Properties of Perfluorinated Sulfonic Acid Membranes: An Investigation of Hydration Based on Absorption Spectra

2017 ◽  
Vol 71 (11) ◽  
pp. 2504-2511 ◽  
Author(s):  
Daniele T. Dias ◽  
Guy Lopes ◽  
Tales Ferreira ◽  
Ivanir L. Oliveira ◽  
Caroline D. Rosa
Keyword(s):  
Sulfonic Acid ◽  
Room Temperature ◽  
Water Retention ◽  
Structural Changes ◽  
Optical Characterization ◽  
Scanning Calorimetry ◽  
Experimental Procedure ◽  
Nafion Membranes ◽  
Perfluorinated Sulfonic Acid

The Nafion membranes are widely used in electrochemical applications such as fuel cells, chlor-alkali cells, and actuators–sensors. In this work, the thermal-optical characterization of Nafion in acid form was performed by photoacoustic spectroscopy, thermogravimetry, and differential scanning calorimetry. In the experimental procedure three distinct hydration levels were considered: (1) pristine membrane (λ ≅ H2O/–SO3H ≅ 5.6); (2) swelling process (λ ≅ 17.4); and (3) drying at controlled room temperature after swelling process (λ ≅ 6.5). The discovered behaviors showed significant irreversible structural changes induced by water retention in the membrane. These structural changes depend on the water population present in the clusters and also affect the directional thermal diffusivity of the membrane irreversibly.

Determination of the Physical Properties of Oil Sands Components using Scanning Probe Microscopy

2015 ◽  
Vol 1754 ◽  
pp. 69-74
Author(s):  
Ravi Gaikwad ◽  
Tinu Abraham ◽  
Aharnish Hande ◽  
Fatemeh Bakhtiari ◽  
Siddhartha Das ◽  
...  
Keyword(s):  
Oil Sands ◽  
Structural Changes ◽  
Rational Approach ◽  
Kelvin Probe ◽  
Scanning Calorimetry ◽  
Probe Microscopy ◽  
Kelvin Probe Microscopy ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTAtomic force microscopy is employed to study the structural changes in the morphology and physical characteristics of asphaltene aggregates as a function of temperature. The exotic fractal structure obtained by evaporation-driven asphaltene aggregates shows an interesting dynamics for a large range of temperatures from 25°C to 80°C. The changes in the topography, surface potential and adhesion are unnoticeable until 70°C. However, a significant change in the dynamics and material properties is displayed in the range of 70°C - 80°C, during which the aspahltene aggregates acquire ‘liquid-like’ mobility and fuse together. This behaviour is attributed to the transition from the pure amorphous phase to a crystalline liquid phase which occurs at approximately 70°C as shown by using Differential Scanning Calorimetry (DSC). Additionally, the charged nature of asphaltenes and bitumen is also explored using kelvin probe microscopy. Such observations can lead to the development of a rational approach to the fundamental understanding of asphaltene aggregation dynamics and may help in devising novel techniques for the handling and separation of asphaltene aggregates using dielectrophoretic methods.

scholarly journals The effect of structural changes during sintering on the electric and magnetic traits of the Ni96.7Mo3.3 alloy nanostructured powder

2009 ◽  
Vol 41 (2) ◽  
pp. 175-184 ◽  
Author(s):  
L. Ribic-Zelenovic ◽  
M. Spasojevic ◽  
A. Maricic ◽  
M.M. Ristic
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Permeability ◽  
Structural Relaxation ◽  
Crystalline Phase ◽  
Structural Changes ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Fcc Lattice ◽  
Lower Permeability ◽  
Structural Powder

Ni96.7Mo3.3 powder was electrochemically obtained. An X-ray diffraction analysis determined that the powder consisted of a 20% amorphous and 80% crystalline phase. The crystalline phase consisted of a nanocrystalline solid nickel and molybdenum solution with a face-centred cubic (FCC) lattice with a high density of chaotically distributed dislocations and high microstrain value. The scanning electronic microscopy (SEM) showed that two particle structures were formed: larger cauliflower-like particles and smaller dendriteshaped ones. The thermal stability of the alloy was examined by differential scanning calorimetry (DSC) and by measuring the temperature dependence of the electrical resistivity and magnetic permeability. Structural powder relaxation was carried out in the temperature range of 450 K to 560 K causing considerable changes in the electrical resistivity and magnetic permeability. Upon structural relaxation, the magnetic permeability of the cooled alloy was about 80% higher than the magnetic permeability of the fresh powder. The crystallisation of the amorphous portion of the powder and crystalline grain increase occurred in the 630 K to 900 K temperature interval. Upon crystallisation of the amorphous phase and crystalline grain increase, the powder had about 50% lower magnetic permeability than the fresh powder and 3.6 times lower permeability than the powder where only structural relaxation took place.

Assessment of the technical condition of mines with mechanical fuses

2021 ◽  
Vol 2021 (1) ◽  
pp. 1-12
Author(s):  
Adam Kubecki ◽  
Cezary Śliwiński ◽  
Janusz Śliwiński ◽  
Ireneusz Lubach ◽  
Leszek Bogdan ◽  
...  
Keyword(s):  
Construction Materials ◽  
Armed Forces ◽  
Operational Reliability ◽  
Strength Properties ◽  
Technical Condition ◽  
Armed Conflicts ◽  
Long Term Storage ◽  
Precise Adjustment ◽  
Main Charge ◽  
Materials Used

Contemporary armed conflicts reveal that the use of effective mine barriers has a significant impact on the course of hostilities. Therefore, the Polish Armed Forces selected reliable and effective explosive ordnance as a priority, both newly-acquired material and those currently in operation. For this reason, among others, strict supervision over the technical condition of mines is exercised, in particular during their long-term storage. The reasons behind the increased mine unreliability may include physical and chemical changes in the construction materials used (corrosion, deformations, loss of strength properties), deterioration of the physicochemical properties of the main charge, booster and primer-detonator, inadequate technical condition of the safety components, or the failure of mine fuse mechanisms. In order to assess the mine's operational reliability, each mine fuse subassembly is examined and then a check of the entire assembled mine is performed. This requires proper planning of the full test cycle and the use of inspected and calibrated measuring devices and test stands enabling the precise adjustment of mechanical and climatic stress parameters.

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