This paper addresses the challenge of evaluating the air permeability of structural concrete in situ, using non-destructive techniques. Specifically, it aims to reconcile air permeability ...measurements made in the field with those made in the laboratory. Permeability measurements in the laboratory and in the field use both under pressure and in vacuum techniques in steady or unsteady states. Differences between the methods may arise from pressure or flow regime variations, or flow direction control. The study proposes a methodology for evaluating air permeability in the field using an existing vacuum technique and an original numerical inverse analysis. An experimental programme using different protocols of permeability measurement with vacuum techniques analysed by numerical modelling is used to understand the differences observed experimentally.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To determine the best combination of parameters for honey drying with ultrasonic vacuum drying technology, this study evaluated the effect of ultrasonic power and frequency on the drying kinetics of ...honey. Three ultrasonic frequencies and two ultrasonic powers were chosen to investigate the influence on water transport, storage stability and microstructural changes during ultrasonic vacuum drying. Among all the conditions studied, 40 kHz 80 W was found to be the best with fastest drying rate and shortest drying time. Through the low-field nuclear magnetic resonance analysis, the ultrasonic vacuum drying of honey could effectively remove bound water at 40 kHz frequency coupled with high ultrasonic power. Ultrasonic power and frequency played a positive role in accelerating the mass transfer process. Meanwhile, the honey powder dried at 28 kHz 40 W had the best storability with the highest glass transition temperature (T
g
) value measured by differential scanning calorimetric. According to the changing trend of T
g
, the average molecular weight of carbohydrate in honey was altered due to the impact of different ultrasonic power and frequency, especially at 40 kHz 80 W. The effects on mass transfer properties were confirmed with microstructural observations using scanning electron microscopy. The new findings on the impact of power and frequency on ultrasonic vacuum drying can be potentially beneficial for future food processing development.
Full text
Available for:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This article describes the vacuum system of the KTM tokamak and also presents an algorithm for the technological mode of conditioning of the tokamak vacuum chamber (VC) performed before and during ...the experiment and its influence on production of glow discharges. The applied procedure of the vacuum chamber preparation, despite the atmospheric leakage in 2021, provided the possibility to develop conditions for conducting experiments at the KTM tokamak and to obtain discharges with the highest currents and discharge durations for this facility achievable at the time of writing of this article. As a result of the analysis of experimental data, the conditions have been established under which plasma discharges are not formed.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The aim of this study was to study the strengthening effect of ultrasonic vacuum technique on the drying kinetics, moisture distribution, and microstructure of honey using low-field nuclear magnetic ...resonance and scanning electron microscopy. Results showed that ultrasonic vacuum drying technique could substantially shorten the drying time from 600 to 60 min, compared with vacuum drying. The sonochemical effects of ultrasonic vacuum drying were enhanced with the increased ultrasonic power and were more obvious in the initial stage of drying. This finding is consistent with the effective water diffusion coefficient results. The non-linear fitting analysis of experimental data on seven kinds of thin-layer drying mathematical models showed that logarithmic model is more suitable for describing the law of moisture change in honey during ultrasonic vacuum drying than the other models because of its higher regression coefficient value (≥0.99) and smaller reduced chi-square and root mean square error values (≤0.01). In addition, low-field nuclear magnetic resonance results showed that the increase in ultrasonic power accelerated the migration of bound water to immobilized water in honey samples. Scanning electron microscopy results showed that the porous structure formed by increasing the ultrasonic power is also conducive to the rapid migration and drying of moisture. In conclusion, ultrasonic vacuum drying technique is an effective and safe way for drying viscous materials compared with vacuum drying technique.
Full text
Available for:
NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
The anionic polymerization of styrene and 1,3-butadiene in the presence of phosphazene bases (t-BuP4, t-BuP2 and t-BuP1), in benzene at room temperature, was studied. When t-BuP1 was used, the ...polymerization proceeded in a controlled manner, whereas the obtained homopolymers exhibited the desired molecular weights and narrow polydispersity (Ð < 1.05). In the case of t-BuP2, homopolymers with higher than the theoretical molecular weights and relatively low polydispersity were obtained. On the other hand, in the presence of t-BuP4, the polymerization of styrene was uncontrolled due to the high reactivity of the formed carbanion. The kinetic studies from the polymerization of both monomers showed that the reaction rate follows the order of t-BuP4/sec-BuLi >>> t-BuP2/sec-BuLi >> t-BuP1/sec-BuLi > sec-BuLi. Furthermore, the addition of t-BuP2 and t-BuP1 prior the polymerization of 1,3-butadiene allowed the synthesis of polybutadiene with a high 1,2-microstructure (~45 wt %), due to the delocalization of the negative charge. Finally, the one pot synthesis of well-defined polyester-based copolymers PS-b-PCL and PS-b-PLLA, PS: Polystyrene, PCL: Poly(ε-caprolactone) and PLLA: Poly(L-lactide), with predictable molecular weights and a narrow molecular weight distribution (Ð < 1.2), was achieved by sequential copolymerization in the presence of t-BuP2 and t-BuP1.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
•Necrotizing fasciitis is a very rare complication, especially in head and neck region.•Diagnosis and treatment have to be quickly and aggressive because of its rapidly fatal complication.•Negative ...wound pressure therapy is a new technic that has emerge in treating complicated wounds.•This new therapy is rarely use in maxillofacial area.
Necrotizing fasciitis is a severe soft tissue infection very uncommon in head and neck. This infection could be very aggressive involving subcutaneous tissue and fascial planes and can be rapidly fatal. Negative pressure wound therapy (NPWT) has emerge recently and became very popular in treating complicated wounds. A case of necrotizing fasciitis in cervical region from an odontogenic infection is presented. After surgical debridement, a NPWT device was installed. NPWT provides advantages compared to conventional debridement and drainage. This method is recommended as an alternative in treating necrotizing fasciitis in head and neck, because it eradicates infection and provides comfort to the patient.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Several non-vacuum based approaches have been employed to deposit the Cu(In,Ga)Se2 layer in photovoltaic devices, but most of them use processing temperatures in the vicinity of 500°C. Here, we ...present the results on a facile solution-based deposition technique for CuInSe2 (CISe) and CuIn(S,Se)2 (CISSe) thin films with deposition temperatures of 300°C. CuxSe (1.5≤x≤2) or CuyS (1≤y≤2) precursor films deposited on a substrate were reacted with InCl3 and Se reactants in oleylamine to form CISe or CISSe thin films of the desired thickness, composition and crystal structure. Solar cells processed from these films on Mo-coated glass substrates demonstrated an efficiency of 2% under AM 1.5 illumination. We also present external quantum efficiency and capacitance–voltage measurements from these devices providing insights into the device performance.
► We present a solution-based deposition technique for CuInSe2 films at 300°C. ► Lower temperatures, same number of steps enable processing on flexible substrates. ► Solar cells demonstrate an efficiency of 2%.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This volume presents the first critical edition of books III and IV of the final redaction of John Buridan's Questions Commentary on Aristotle's Physics. The edition is accompanied by a detailed ...guide to the contents of Buridan's questions.
The novel functionalized triblock copolymers, poly(4-vinylphenyl)dimethylsilane-
b-polybutadiene-
b-poly(4-vinylphenyl)- dimethylsilane (PVPDMS-
b-PBd-
b-PVPDMS), were synthesized by anionic ...polymerization method using high vacuum technique. The hydrocarbon-soluble dilithium initiator synthesized from 1,3-di1-(methylphenyl)ethenylbenzene (MPEB) was used to synthesize polybutadiene (PBd) precursors and the triblock copolymers in the presence of
sec-BuOLi. The precursors and copolymers were characterized by size exclusion chromatography (SEC),
1HNMR and DSC techniques.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Light and Vacuum presents a synthesis of selected fundamental topics of electromagnetic wave theory and quantum electrodynamics (QED) and analyzes the main theoretical difficulties encountered to ...ensure a coherent mathematical description of the simultaneous wave–particle nature of light, put in evidence by the experiments. The notion and the role of the quantum vacuum, strongly related to light, are extensively investigated. Classical electrodynamics issued from Maxwell's equations revealed the necessity of introducing the notion of volume for an electromagnetic wave to stand entailing precise values of cut-off wavelengths to account for the shape and dimensions of the surrounding space. Conversely, in QED, light is considered to be composed of point particles disregarding the conceptual question on how the frequency of oscillating electric and magnetic fields may be attributed to a point particle. To conciliate these concepts, the book provides a comprehensive overview of the author's work, including innovative contributions on the quantization of the vector potential amplitude at a single photon state, the non-local simultaneous wave–particle mathematical representation of the photon and finally the quantum vacuum. The purpose of the advanced elaborations is to raise questions, give hints and answers, and finally aspire for further theoretical and experimental studies in order to improve our knowledge and understanding on the real essence of Light and Vacuum.
PDF
