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Wyniki wyszukiwania dla: NON-EQUILIBRIUM GAS
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Development of Gas Sensor Array for Methane Reforming Process Monitoring
PublikacjaThe article presents a new method of monitoring and assessing the course of the dry methane reforming process with the use of a gas sensor array. Nine commercially available TGS chemical gas sensors were used to construct the array (seven metal oxide sensors and two electrochemical ones). Principal Component Regression (PCR) was used as a calibration method. The developed PCR models were used to determine the quantitative parameters...
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Electrocatalytic gas sensor with reference layer
PublikacjaIn recent years electrochemical gas sensors based on solid state electrolytes have been intensively developed. They are easy to obtain, use and relative durable. Nasicon is one of the most promising materials, which have been used in construction of gas sensors. Most of these devices work in potentiometric or amperometric mode. However, some works are dedicated to sensors working in electrocatalytic mode. Principle of operation...
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APPLICABILITY OF INLET AIR FOGGING TO MARINE GAS TURBINE
PublikacjaThe dependency of marine gas turbine on the ambient temperature leads to a decrease of the gas turbine power output in arid areas. Very often gas turbine power output demand is high and the power margins originally designed into the driver , has been exhausted. In such circumstances the inlet air fogging is an effective compensation of gas turbine power. In this paper an analysis of inlet air fogging applicability to marine gas...
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Dopants and gas modifiers in ion mobility spectrometry
PublikacjaThe ion mobility techniques, including the most commonly used drift-tube ion mobility spectrometry (IMS) and differential mobility spectrometry (DMS), are used successfully for the detection of a wide range of organic compounds in the gas phase. In order to improve detection quality, admixtures are added to gas streams flowing through the detector. Dopants mostly prevent the ionization of interfering chemicals however, better detection...
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Interaction of cisplatin and two potential antitumoral platinum(ii) complexes with a model lipid membrane: a combined NMR and MD study
PublikacjaIn this study, the interaction of cisplatin (1) and two potential antitumoral Pt(II) complexes (2 and 3) with a model DMPC bilayer was investigated by multinuclear NMR spectroscopy and MD simulations in order to understand its implication for the different antitumoral properties shown by the three complexes. In particular, 31P, 13C and 2H solid state NMR experiments were performed to obtain information on the phase structure, phase...
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Electrochemical synthesis of 2D copper coordination-polymers: Layer-stacking deviation induced by the solvent and its effect on the adsorptive properties
PublikacjaA 2D Cu-based Metal-Organic Framework (MOF), namely copper-terephthalate (Cu(1,4-BDC)), was successfully synthesized by electrochemical method for effective methylene blue (MB) sorption from aqueous solutions. The composition, morphology, and the presence of functional groups in the obtained material were verified by Fourier Transform Infrared spectroscopy (FTIR), Powder X-Ray Diffraction (PXRD), Thermal (TGA), and Elemental (EA)...
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Defending against Fake VIP in Scant-Transparency Information Systems with QoS Differentiation
PublikacjaIn client-server information systems with quality of service (QoS) differentiation, Client may deplete Server’s resources by demanding unduly high QoS level. Such QoS abuse has eluded systematic treatment; known defenses using Client authorization, payments, or service request inspection prior to QoS assignment, are heuristic and environment-specific. We offer a game-theoretic approach on the premise that a service request is occasionally...
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Hyaluronan-Chondroitin Sulfate Anomalous Crosslinking Due to Temperature Changes
PublikacjaGlycosaminoglycans are a wide class of biopolymers showing great lubricating properties due to their structure and high affinity to water. Two of them, hyaluronic acid and chondroitin sulfate, play an important role in articular cartilage lubrication. In this work, we present results of the all-atom molecular dynamics simulations of both molecules placed in water-based solution. To mimic changes of the physiological conditions,...
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Effect of osmolytes of different type on DNA behavior in aqueous solution. Experimental and theoretical studies
PublikacjaOsmolytes, the small organic molecules accumulated in cells under environmental stress, can modulate the stability of biopolymers such as proteins and DNA. In spite of many years of research, there is no established molecular mechanism of the influence of osmolytes on DNA structure. Here, we used two model osmolytes that denature (urea) or stabilize (trimethylglycine, TMG) proteins to study their effect on DNA in aqueous solutions...
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Changes of Conformation in Albumin with Temperature by Molecular Dynamics Simulations
PublikacjaThis work presents the analysis of the conformation of albumin in the temperature range of 300K – 312K, i.e., in the physiological range. Using molecular dynamics simulations, we calculate values of the backbone and dihedral angles for this molecule. We analyze the global dynamic properties of albumin treated as a chain. In this range of temperature, we study parameters of the molecule and the conformational entropy derived from...
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Design Analysis of Micro Gas Turbines in Closed Cycles
PublikacjaThe problems faced by designers of micro-turbines are connected with a very small volume flow rate of working media which leads to small blades’ height and high rotor speed. In the case of gas turbines this limitation can be overcome by the application of a closed cycle with very low pressure at the compressor inlet (lower than atmospheric pressure). In this way we may apply a micro gas turbine unit of accepted efficiency to work...
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Exhaled breath analysis by resistive gas sensors
PublikacjaBreath analysis has attracted human beings for centuries. It was one of the simplest methods to detect various diseases by using human smell sense only. Advances in technology enable to use more reliable and standardized methods, based on different gas sensing systems. Breath analysis requires the detection of volatile organic compounds (VOCs) of the concentrations below individual ppm (parts per million). Therefore, advanced detection...
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Sulfur compounds: Gas chromatography
PublikacjaSulfur compounds, due to their properties, are responsible for the damage of our environment. For this reason sulfur containing compounds are of constant concern in many fields. Gas chromatography (GC), due to combination of separation capability and sensitive detection is a prime technique for the analysis of thes compounds in various matrices. The chapter rewies general problems of the determination of these compounds by GC and...
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Non-isolating 2-bondage in graphs
PublikacjaA 2-dominating set of a graph G=(V,E) is a set D of vertices of G such that every vertex of V(G)D has at least two neighbors in D. The 2-domination number of a graph G, denoted by gamma_2(G), is the minimum cardinality of a 2-dominating set of G. The non-isolating 2-bondage number of G, denoted by b_2'(G), is the minimum cardinality among all sets of edges E' subseteq E such that delta(G-E') >= 1 and gamma_2(G-E') > gamma_2(G)....
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New developments in preparation and use of standard gas mixtures
PublikacjaStandard gas mixtures are commonly applied in all stages of analytical work related to the analysis of gaseous samples. Numerous techniques for generating standard gas mixtures are in use. In this article, we present new developments regarding the production of standard gas mixtures, with particular focus on improvements in the application of dynamic techniques for generating them. Furthermore, we describe the application of new...
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Resistive gas sensors – Perspectives on selectivity and sensitivity improvement
PublikacjaResistive gas sensors are very popular and relatively inexpensive; they can operate at elevated or room temperature for years on end. The main disadvantage of resistive gas sensors is their limited selectivity and sensitivity, but various methods have been applied to improve their behavior. The composition of the porous gas sensing layer, or changes in the sensor’s operating temperature, can enhance the gas detection ability. Furthermore, emerging...
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Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines. Part II. Unsteady processes
PublikacjaThe second part of the article presents the results of operating diagnostic tests of a two- and three-shaft engine with a separate power turbine during the start-up and acceleration of the rotor units. Attention was paid to key importance of the correctness of operation of the automatic engine load control system, the input for which, among other signals, is the rate of increase of the exhaust gas flow temperature. The article...
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Equilibrium of Trichloroethylene Adsorption from Aqueous Solution onto Activated Carbons
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Analytical fluctuation enhanced sensing by resistive gas sensors
PublikacjaResistance fluctuations across polarised resistive gas sensors were studied in detail to evaluate sensor working conditions for detecting methane and ammonia at various concentrations. The 1/f noise component typically dominates other noise sources up to a few kHz and can be utilised to improve gas selectivity when compared with measurements of the sensor DC resistance. The Arrhenius plot was created and the activation energy for...
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An electronic nose for quantitative determination of gas concentrations
PublikacjaThe practical application of human nose for fragrance recognition is severely limited by the fact that our sense of smell is subjective and gets tired easily. Consequen tly, there is considerable need for an instrument that can be a substitution of the human sense of smell. Electronic nose devices from the mid 1980s are used in growing number of applications. They comprise an array of several electrochemical gas sensors...
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Novel Desorber for Online Drilling Mud Gas Logging
PublikacjaThis work presents the construction solution and experimental results of a novel desorber for online drilling mud gas logging. The traditional desorbers use mechanical mixing of the liquid to stimulate transfer of hydrocarbons to the gaseous phase that is further analyzed. The presented approach is based on transfer of hydrocarbons from the liquid to the gas bubbles flowing through it and further gas analysis. The desorber was...
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Influence of operation temperature instability on gas sensor performance
PublikacjaGas sensors based on the semiconducting metal-oxides, such as SnO2, have been found to be very useful for detecting a wide range of gases. The reversible interactions of the gas with the surface of the sensing layer made of semiconducting metal-oxides are responsible for changes of sensor resistance which is usually used as a measure of sensor response. Semiconductor gas sensors are commercially available and applied in numerous...
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Non-linear FEM analysis of pounding-involved response of buildings under non-uniform earthquake excitation
PublikacjaThe aim of the paper is to show the results of the study investigating the influence of non-uniform earthquake excitation, due to spatial seismic effects connected with the propagation of seismic wave, on the pounding-involved response of two buildings. The three-dimensional non-linear FEM analysis has been conducted using the detailed models of colliding structures. Acceleration records for different structural supports have been...
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Adsorptive Removal of Aqueous Phase Crystal Violet Dye by Low-Cost Activated Carbon Obtained from Date Palm (L.) Dead Leaflets
PublikacjaUp to now, water pollution is still one of the important issues and challenges worldwide, due to its environmental, economic and human life impacts. It is also remains a challenge to environment scientists and technologists. Nowadays, the textile dyeing industry is considered one of the largest water consuming industries and produces large volumes of colored wastewater in its dyeing and finishing process. In this study, date palm...
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On nonlinear dilatational strain gradient elasticity
PublikacjaWe call nonlinear dilatational strain gradient elasticity the theory in which the specific class of dilatational second gradient continua is considered: those whose deformation energy depends, in an objective way, on the gradient of placement and on the gradient of the determinant of the gradient of placement. It is an interesting particular case of complete Toupin–Mindlin nonlinear strain gradient elasticity: indeed, in it, the...
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Effect of Nanohydroxyapatite on Silk Fibroin–Chitosan Interactions—Molecular Dynamics Study
PublikacjaFibroin–chitosan composites, especially those containing nanohydroxyapatite, show potential for bone tissue regeneration. The physicochemical properties of these biocomposites depend on the compatibility between their components. In this study, the intermolecular interactions of fibroin and chitosan were analyzed using a molecular dynamics approach. Two types of systems were investigated: one containing acetic acid and the other...
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Why do G-quadruplexes dimerize through the 5’-ends? Driving forces for G4 DNA dimerization examined in atomic detail
PublikacjaG-quadruplexes (G4) are secondary structures formed by guanine-rich nucleic acid sequences and shown to exist in living cells where they participate in regulation of gene expression and chromosome maintenance. G-quadruplexes with solvent-exposed guanine tetrads show the tendency to associate together through cofacial stacking, which may be important for packaging of G4-forming sequences and allows for the design of higher-order...
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Selected local stability problems of channel section flanges made of aluminium alloys
PublikacjaThe paper addresses the issue of local buckling of compressed flanges of cold-formed thin-walled channel columns and beams with nonstandard flanges composed of aluminium alloys. The material behaviour follows the Ramberg–Osgood law. It should be noted that the proposed solution may be also applied for other materials, for example: stainless steel, carbon steel. The paper is motivated by an increasing interest in nonstandard cold-formed...
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Interaction of Acoustic and Thermal Modes in the Gas with Nonequilibrium Chemical Reactions: Possibilities of Acoustic Cooling
PublikacjaNonlinear generation of thermal mode during propagation of dominative sound in a chemically reacting gas is considered. The dynamic equation of excess temperature associated with the thermal mode is derived. It is instantaneous and includes quadratic nonlinear acoustic source reflecting the nonlinear character of interaction between acoustic and non-acoustic types of gas motion. Both periodic and aperiodic sound may be considered...
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Nonlinear Interaction of Modes in a Planar Flow of a Gas with Viscous and Thermal Attenuation
PublikacjaThe nonlinear interaction of wave and non-wave modes in a gas planar flow are considered. Attention is mainly paid to the case when one sound mode is dominant and excites the counter-propagating sound mode and the entropy mode. The modes are determined by links between perturbations of pressure, density, and fluid velocity. This definition follows from the linear conservation equations in the differential form and thermodynamic...
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Instantaneous Heating and Cooling Caused by Periodic or Aperiodic Sound of Any Characteristic Duration in a Gas with Vibrational Relaxation
PublikacjaThermodynamic relaxation of internal degrees of a molecule's freedom in a gas occurs with some characteristic time. This makes wave processes in a gas behave differently depending on the ratio of characteristic duration of perturbations and the relaxation time. In particular, generation of the secondary non-wave modes by intense sound in a nonlinear flow dependens on frequency. These kinds of interaction are considered in this...
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Electrocatalytic Gas Sensor with Reference Layer
PublikacjaThis paper presents studies of gas sensors prepared in ceramic technology with Nasicon as a solid electrolyte. Sensors work in the voltammetric mode thus based on the excitation of a sensor with a periodic potential signal while current response is recorded. The main aim is to investigate a Bi8Nb2O17 reference layer influence on sensor properties. Sensors I-V characteristics in different concentration of nitrogen dioxide have been...
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Possibilities of Increasing the Overall Efficiency of Gas-steam CHP Microplant
PublikacjaThe paper presents ways to increase the efficiency of a gas-steam micro power plant by modifying the cycle combination. The modification consists in partial release of the fluid downstream of the gas turbine and using it for ORC fluid overheating and evaporation. Advantages of this solution over the simplest gas and steam cycles’ combination are demonstrated.
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Identification of volatile compounds based on the electrocatalytic gas sensor responses
PublikacjaMeasured response in case of electrocatalytic gas sensors is in form of a voltamperometric characteristic. Current-voltage (I-V) response shape depends on the gas type and its concentration. Such response contains significantly more information comparing with typical electrochemical sensors, but is quite difficult to analyze. When I-V curve contains current peaks, position of such peaks can be used...
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Carbon dioxide sequestration during shale gas recovery
PublikacjaThis paper presents literature on theoretical and practical aspects of gas production from shale using carbon dioxide fracturing. Development of technical and environmental aspects of carbon dioxide fracturing technologies is also considered. Patents applicable to carbon dioxide fracturing are reviewed. There were also conducted researches to evaluate possibility of carbon dioxide sequestration in shale gas reservoirs.
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Security Assessment of a Turbo-Gas Power Plant
PublikacjaCritical infrastructures are exposed to new threats due to the large number of vulnerabilities and architectural weaknesses introduced by the extensive use of information and communication technologies. This paper presents the results of an exhaustive security assessment for a turbo-gas power plant.
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Non-Newtonian Mathematics Instead of Non-Newtonian Physics: Dark Matter and Dark Energy from a Mismatch of Arithmetics
PublikacjaNewtonian physics is based on Newtonian calculus applied to Newtonian dynamics. New paradigms such as ‘modified Newtonian dynamics’ (MOND) change the dynamics, but do not alter the calculus. However, calculus is dependent on arithmetic, that is the ways we add and multiply numbers. For example, in special relativity we add and subtract velocities by means of addition β1⊕β2=tanh(tanh−1(β1)+tanh−1(β2)), although multiplication β1⊙β2=tanh(tanh−1(β1)⋅tanh−1(β2)),...
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Shooting Gas Cylinders to Prevent Their Explosion in Fire
PublikacjaGas cylinders in general, and particularly cylinders containing acetylene, constitute a great potential danger to fire and rescue services involved in salvage operations. Experiments show that gas cylinders with acetylene, oxygen, hydrogen, CNG, LPG or CO2 may blow after short exposition to heat with very destructive effect as fragments of blown cylinder may fly even several hundred meters. In the case of acetylene the explosion...
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New approaches for improving selectivity and sensitivity of resistive gas sensors: a review
PublikacjaPurpose – This paper aims to present the methods of improving selectivity and sensitivity of resistance gas sensors. Design/methodology/approach – This paper compares various methods of improving gas sensing by temperature modulation, UV irradiation or fluctuation-enhanced sensing. The authors analyze low-frequency resistance fluctuations in commercial Taguchi gas sensors and the recently developed tungsten trioxide (WO3) gas-sensing...
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Special Issue: “Non-Destructive Testing of Structures”
PublikacjaThe Special Issue “Non-Destructive Testing of Structures” has been proposed to present recent developments in the field of diagnostics of structural materials and components in civil and mechanical engineering. The papers highlighted in this editorial concern various aspects of non-invasive diagnostics, including such topics as condition assessments of civil and mechanical structures and connections of structural elements, the...
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New approaches for improving selectivity and sensitivity of resistive gas sensors: A review
PublikacjaResistive gas sensors are very popular and reliable but suffer from low selectivity and sensitivity. Various methods have been suggested to improve both features without increasing the number of sensors in gas detection systems. Fluctuation enhanced gas sensing was proposed to improve gas detection efficiency by analyzing low-frequency resistance fluctuations, and noise parameters can be more informative than the single DC resistance...
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A calibration model for gas sensor array in varying environmental conditions
PublikacjaAbstract: Gas-analyzing systems based on gas sensors, commonly referred to as electronic noses, are the systems which enable the recognition of volatile compounds in their working environment and provide the on-line results of analysis. The most commonly used type of sensors in such systems is semiconductor gas sensors. They are considered to be the most reliable in the long-term applications (more than 1 year), however,...
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A calibration model for gas sensor array in varying environmental conditions
PublikacjaAbstract: Gas-analyzing systems based on gas sensors, commonly referred to as electronic noses, are the systems which enable the recognition of volatile compounds in their working environment and provide the on-line results of analysis. The most commonly used type of sensors in such systems is semiconductor gas sensors. They are considered to be the most reliable in the long-term applications (more than 1 year), however,...
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Thermal Self-Action Effects of Acoustic Beam in a Gas with Reversible or Irreversible Chemical Reaction
PublikacjaThermal self-action of acoustic beam in a gas where an exothermic chemical reaction takes place, is studied. This kind of thermal self-action differs from that in a newtonian fluid. In dependence on the type of a chemical reaction, reversible or not, heating or cooling of a medium occurs. A beam in the case of the irreversible reaction may be unusually self-focusing. The self-action effects relating to wave beams containing shock...
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Features extraction from the electrocatalytic gas sensor responses
PublikacjaOne of the types of gas sensors used for detection and identification of toxic-air pollutant is an electrocatalytic gas sensor. The electrocatalytic sensors are working in cyclic voltammetry mode, enable detection of various gases. Their response are in the form of I-V curves which contain information about the type and the concentration of measured volatile compound. However,...
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Inspection of Gas Pipelines Using Magnetic Flux Leakage Technology
PublikacjaMagnetic non-destructive testing methods can be classified into the earliest methods developed for assessment of steel constructions. One of them is the magnetic flux leakage technology. A measurement of the magnetic flux leakage is quite commonly used for examination of large objects such as tanks and pipelines. Construction of a magnetic flux leakage tool is relatively simple, but a quantitative analysis of recorded data is a...
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Scalable Measurement System for Multiple Impedance Gas Sensors
PublikacjaAuthor proposes scalable architecture of the measurement system for gas sensor with impedance dependance of the gas concentration. The main part of the system is a single-board impedance analyser. The number of analysers working in parallel can be configured according to specific application. The system is controlled by a single computer which organises the measurement cycle and store the acquired measurement data. The system is...
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Gas turbines – technological development and potential use in CAES systems
PublikacjaThis article briefly describes Compressed Air Energy Storage (CAES), focusing on the technological development of one of the key elements of such systems – the gas turbines. It presents the basic parameters and features of gas turbines, as well as turbine classes with example models. Main tendencies in the structural and technological development are discussed. Changes and trends on electric energy markets are becoming more and...
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Non-destructive Testing of Wooden Elements
PublikacjaExamining the condition of wooden elements is crucial from the perspective of proper structure performance. If the deterioration in the internal wood condition, which displays no symptoms visible from the outside, is detected, the further spread of the deterioration can be prevented. Test results often point to the necessity of conducting repairs and, renovations, replacing the structure of wooden beams, or even substituting a...
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Two-dimensional gas chromatography – principles and application in fruits analysis
PublikacjaTwo-dimensional gas chromatography is a rapidly developing analytical technique. One of the major uses of this technique is its use for food analysis. The paper presents the principle of operation and history of this analytical technique. The specification of the two-dimensional gas chromatography technique has been discussed. The principles of separation of ingredients and application of the method, particularly in the analysis...