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  1. 42 Acta Physica Polonica A

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  1. 2 2018

  2. 8 2017

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  5. 4 2014

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  1. 5 Milczarek J.

  2. 4 Fijał-Kirejczyk I.

  3. 4 Zeleňák V.

  4. 4 Zeleňáková A.

  5. 3 Jurkowski Z.

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1
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Direct and Postsynthetic Functionalization of Mesoporous B-SBA-15-SO₃H Acid Catalyst and Application to Methyl Propionate Esterification

100%
Erdem B., Azko Ç., Erdem S., Öksüzoğlu R.
Acta Physica Polonica A
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2017
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vol. 132
|
issue 3
756-759
EN
Organic functionality can be added to mesoporous silicates in two ways: either by covalent grafting (postsynthetic) of various functional groups onto the channel walls or by incorporating functionalities directly during the synthesis (one-pot). If the grafted catalytically active groups experience similar environments and are isolated from each other, catalysis process is greatly facilitated. For this purpose, boric acid, as boron source, was added into the initial reaction mixture and then acid functionalization was performed by post and direct method. The obtained acid catalysts were tested in the esterification of propionic acid with methanol and the activity of these new materials was compared to that of SBA-15-SO₃H. Boron addition has facilitated the methyl propionate esterification for both postsynthetic and direct functionalized acid catalyst. Boron incorporated and postsynthetic functionalized mesoporous acid catalyst has highly enhanced the esterification reaction, compared to direct functionalized acid catalyst. The post functionalization method seems to be superior to one-pot functionalization method for preparation of mesoporous acid catalysts.
2
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Phase Transition in Quasi-Two-Dimensional Horizontally Driven Granular System

100%
Shah S., Li Y., Khan W., Din N., Chand R.
Acta Physica Polonica A
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2012
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vol. 121
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issue 3
699-702
EN
In an experimental setup, consisting of quasi-two-dimensional square cell, the motion of monodisperse spherical steel balls is studied. The cell is vibrated horizontally to eradicate the compaction of balls due to gravity. By raising the number density of the steel balls, the dilute fluid has been gradually alternated into dense fluid. The temperature of granular media, along the driven and transverse directions, has been found to be anisotropic. Transition from granular gas to the liquid-like fluid has been observed. The radial distribution function of the balls in the cell is investigated for the authentication of the structural changes. Furthermore, the fast Fourier transformation for the 2D system is carried out to confirm these changes.
3
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Liquid Phase Contained in Porous Rock as Observed by Proton Magnetic Relaxation

100%
Harańczyk H., Wójcik A.
Acta Physica Polonica A
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2000
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vol. 98
|
issue 1-2
153-161
EN
High power proton relaxometry was applied to investigate the liquid phase contained in porous rock. Proton free induction decays and spin-lattice relaxation times allowed us to investigate the pore distribution and the contribution of mobile and of immobilized liquid. The differences in pore distributions in oil-containing limestone and in Węglowicki sandstone were found. The fractal exponent for pore distribution in Węglowicki sandstone was fitted using both stretched exponential and modified stretched exponential models. The results of both approaches are compared.
4
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Influence of Temperature and Impregnation Ratio of H_3PO_4 on the Production of Activated Carbon from Hazelnut Shell

100%
Örkün Y., Karatepe N., Yavuz R.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
277-280
EN
Hazelnut shell was used as a precursor in the production of activated carbon by chemical activation with H_3PO_4 since there is a huge volume of such a solid waste resulting from the hazelnut production in eastern Black Sea region of Turkey. Effects of final activation temperature, time and H_3PO_4 concentration used in the impregnation stage on the porous development were investigated. Activation at low temperature represented that micropores were developed first and then mesoporosity developed, enhanced up to 400C and then started to decrease due to possible shrinking of pores. The optimum temperature for hazelnut shell was found to be around 400C on the basis of total pore volume and the Brunauer-Emmett-Teller surface area. It was clearly demonstrated that H_3PO_4 concentration used in the impregnation stage was not only effective for development of surface area and pore volumes but also an effective tool for tailoring the pore structure and size distribution.
5
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The Usage of Perlitic Pumice from İzmir-Menderes (Turkey) in the Production of Low-Strength Lightweight Concrete

100%
Ceylan H., Saraç S.
Acta Physica Polonica A
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2017
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vol. 132
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issue 3
667-669
EN
Lightweight aggregates, used to produce cavity blocks in the construction sector, vary according to their technical properties and thus, technical analyses should be performed on lightweight aggregate specimens. Lightweight aggregates, like pumice, are widely employed for the production of construction elements, used as light masonry units. In literature there are studies related to applications of various lightweight aggregates, such as volcanic slag, ignimbrite and expanded clay, in addition to pumice, to produce porous cavity blocks. This study investigates the usability of perlitic pumice formations, present around Menderes, İzmir (Turkey), as lightweight aggregate. Many experiments were conducted to investigate this possibility and to determine the optimum mixing ratios of aggregate. Based on the results, for 10% of cement by volume, the optimum aggregate mixing ratio was 40% 0-4 mm and 60% 4-8 mm.
6
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AC Magnetic Susceptibility Study of Fe and Co Based Nanoparticles

80%
Zeleňáková A., Kováč J., Zeleňák V.
Acta Physica Polonica A
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2014
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vol. 126
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issue 1
222-223
EN
We have investigated magnetic properties of three different samples composed of magnetic Fe or Co core and protective Au or Pt metallic shell, namely Fe@Au, Co@Au and Fe@Pt samples, with sizes of about 10 nm, 8 nm and 5 nm respectively. We have measured and analysed the experimental data of real and imaginary component of ac susceptibility through theoretical laws for non-interacting and interacting particles and we have estimated the strength of their magnetic interactions. Our analyses showed the increase of inter-particle interactions with decreasing particles size.
7
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The Effect of Sodium Chloride on the Process of Drying of Porous Media

80%
Fijał-Kirejczyk I., Milczarek J., Jurkowski Z., Żołądek J.
Acta Physica Polonica A
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2013
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vol. 124
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issue 6
1025-1028
EN
The high temperature drying process of corundum cylinders partially saturated with aqueous solutions of sodium chloride was investigated with neutron imaging technique accompanied with mass and temperature measurements. The statistical analysis of neutron images was applied in order to quantify the time evolution of the process. The substantial slowing down of drying with increasing salt concentration was found. This effect was attributed to increase of viscosity of the solution with increasing salt content as well as to the formation of an outer layer of NaCl on the sample surface.
8
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Drying Kinetics of Particulate Corundum Layers

80%
Cmiel K., Milczarek J., Bam L., Fijał-Kirejczyk I., Jurkowski Z., Żołądek J.
Acta Physica Polonica A
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2013
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vol. 124
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issue 6
1029-1033
EN
The results of studies on drying of layers of particulate corundum performed with digital neutron radiography are presented. The statistical analysis of images was employed to reveal main features of the drying process. It is shown that the first period of drying proceeds within the whole body of the sample. Marked signatures of the end of first period of drying were found for sample mass, temperature, average image brightness as well as standard deviation of brightness time evolutions for the system composed of fine grains. The chaotic nature of this period is delineated by a distinct maximum in the standard deviation of sample image brightness. The presence of the drying front moving from the open surface to the sample bottom is proven to be an attribute of the advanced drying period.
9
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Enhanced Mechanical Performance of Aluminum Glass Fiber Reinforced Foam Material by Cu Modification

80%
Ertürk A., Aydın I.
Acta Physica Polonica A
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2017
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vol. 131
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issue 3
470-473
EN
Glass fiber-reinforced aluminum foam and its modified forms, using 1 and 3 wt.% of Cu, were produced by powder sintering process, using spherical carbamide particles as space holders. The foams with 40 and 60 vol.% porosity fractions were successfully produced after water leaching and sintering procedures. Compression test was performed on foam samples to compare both, the compressive properties and energy absorption behavior of them. The composite foam samples with Cu modification have shown a higher compressive strength than the parent material foam. The average plateau stress and energy absorption capacity of foams produced in this study, achieved via utilizing 3 wt.% Cu, were 7.06 MPa and 3.51 MJ/m³, respectively.
10
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Positron Annihilation Lifetime Spectroscopy Study of the Formation of Mesoporous Materials from the Zeolite Precursor

80%
Bosnar S., Bosnar D., Gržeta B.
Acta Physica Polonica A
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2014
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vol. 125
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issue 3
775-777
EN
In this work, positron annihilation lifetime spectroscopy was used for the structural characterisation of porous materials prepared from amorphous zeolite precursors acting as the starting materials and hexadecyltrimethylammonium bromide acting as a mesoporous template. The best fits of the obtained lifetime spectra provide a four-component exponential decomposition. The lifetime values of the long-lived components point to the presence of mesoporous voids. Infrared and X-ray analyses show that the obtained materials consist partly of a crystalline zeolite structure.
11
Publication available in full text mode
Content available

Water Sorption and Dessiccation in a Portland Cement Paste: Positron Annihilation Results

80%
Consolati G., Dotelli G., Quasso F.
Acta Physica Polonica A
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2001
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vol. 99
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issue 3-4
345-349
EN
Positron annihilation experiments were carried out on a Portland cement paste one year aged, which was subjected to cycles of dessiccation and subsequent water resaturation, in order to study possible changes of the porosity. Analysis of the annihilation time spectra suggests that drying and rewetting treatments do not induce irreversible modifications in the configuration of the finest gel pores.
12
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Formation of Nanostructured Layers for Passivation of High Power Silicon Devices

80%
Šalucha D., Šimkiene I., Sabataityte J.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
1079-1083
EN
Nanocrystalline porous silicon films, which have been formed by using simple wet electrochemical etching process in HF electrolyte, were applied for passivation of high power silicon diodes. An optimal technology was designed to manufacture a uniform layer of porous silicon over the area of the p-n junction. The 8% increase in the yield was achieved onO100 mm diameter wafers with 69 cells of diodes in each, by using a very simple technology for the formation of porous layer for passivation of high power silicon diodes.
13
Content available remote

Properties of Sound Panels Made from Recycled Footwear Treads

80%
Yildiz F., Parlar A., Parlar Z., Bakkal M.
Acta Physica Polonica A
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2017
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vol. 132
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issue 3
936-940
EN
Natural resources have been decreasing with the large expansion of the world's population. In order to supply raw material for production, new recycling approaches should be developed for waste materials. Worn shoes is one of the most common waste products that can be recycled for this purpose. According to the record, shoes are very complex products, as they can be produced from forty different materials, like leather, rubber, polymers etc. Especially the bottom layers of the shoes are made from sound absorbing materials like polyurethane, thermoplastic rubber and PVC. Because today's technology is not able to separate these materials from each other during recycling, they should be used in a homogenised state. Thus these parts were shredded into small granules and mixed. PU binder and hot press were used to obtain samples for tests. In this paper sound absorption, sound isolation, vibration isolation and thermal insulation properties of the tread mixture are investigated. In addition to that, the mechanical properties of the material were also investigated by measuring the compression strength of the material.
14
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Experimental Investigation of Resistive Sensor for High Power Millimetre Wave Pulse Measurement

80%
Simniškis R., Dagys M., Kancleris Ž., Tamošiūnas V.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
1091-1094
EN
An experimental investigation of a high power millimetre wave pulse sensor is presented. Two groups of sensors with a flat frequency response were fabricated according to results of the optimisation. The frequency response and voltage standing wave ratio were measured and compared with results of the electrodynamical simulations. The largest measured sensitivity variation of the best sensors within waveguide frequency range was±8%. The reasonable agreement between measured and simulated values of the sensitivity was obtained.
15
Content available remote

Formation of Porous n-A_3B_5 Compounds

80%
Šimkiene I., Kindurys A., Treideris M., Sabataityte J.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
1085-1090
EN
Porous layers of A_3B_5 compounds were formed on n-type wafers by electrochemical anodic etching. The morphology of nanostructured layers was studied by scanning electron microscopy and atomic force microscopy techniques. The optimal conditions of the formation of porous layers were determined by varying the composition of etching solution, current density and etching time. Large area (1.5×1.5 cm^2) porous layers of uniform porosity were produced by anodization process of n-type A_3B_5 semiconductors,
16
Content available remote

Magnetocaloric Effect in Gd₂O₃@SiO₂ Nanocomposite

80%
Zeleňáková A., Hrubovčák P., Berkutova A., Kapusta O., Zeleňák V.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
810-812
EN
Nanocomposite consisting of Gd₂O₃ nanoparticles embedded in periodical porous silica matrix was investigated with respect to its magnetocaloric properties. Series of field (up to 5 T) dependence of magnetization data were recorded in temperature range 2-52 K. The data were subsequently processed employing Maxwell relation in order to calculate magnetic entropy change (Δ S_M) of the system. Examined nanocomposite exhibited reasonably high value of Δ S_M ≈ 29 J/(kg K) at maximal field change 5 T at the temperature of 2 K which suggests that this material could be feasible for cryomagnetic refrigeration applications.
17
Content available remote

Anion Removal Potential of Complex Metal Oxides Estimated from Their Atomic Scale Structural Properties

80%
Chubar N., Gerda V., Mičušík M., Omastova M., Heister K., Man P., Yablokova G., Banerjee D., Fraissard J.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
1091-1096
EN
The main common idea of two conference papers delivered at OMEE-2017 was to demonstrate an importance of the speciation level knowledge in modern adsorption materials science. In order to prove this, two groups of adsorptive materials were used: three samples of Mg-Al-CO₃ layered double hydroxides produced by different synthesis methods and ten samples of Fe-Ce oxide-based composites with various ratios of Fe-to-Ce. In both cases of studies, it was not possible to find direct correlation between adsorptive performances of the materials and their structural properties obtained by conventional characterisation techniques. However, anion adsorptive removals of each group of inorganic composites correlated with their structural properties studied on the level of speciation. It was shown that strong anion removal potential of Mg-Al-CO₃ layered double hydroxides was associated with richness in speciation of chemical elements (Mg, Al) and interlayer anions (CO₃²¯) as well as with generous hydration. Adsorptive performances of inorganic anion exchangers based on Fe-Ce hydrous oxides were explained by simulation extended X-ray absorption fine structures simulation. The best anion removers were found to be those Fe/Ce oxide-based composites whose Fe outer shells were formed from backscattering oscillations from both O and Fe atoms.
18
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Structure and Magnetic Properties of Three-Dimensional Gadolinium-Based Hybrid Framework

80%
Almáši M., Zeleňáková A., Císařová I., Bednarčík J., Zeleňák V.
Acta Physica Polonica A
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2014
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vol. 126
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issue 1
308-309
EN
In the present work we have focused on the preparation and magnetic study of coordination polymer formed by Gd(III) cations as nodes and formate (HCOO¯; FOR) anions as charge compensating linkers. The prepared complex with formula {[Gd(μ_{3}-FOR)_{3}]}_{n} was characterized by single-crystal X-ray diffraction, and high-energy powder X-ray diffraction. The structural study showed that complex is formed by 3D polymeric network with the shortest Gd-Gd, distances of 3.998 Å. The magnetic properties of the complex were studied by magnetic susceptibility χ_{M}(T) and magnetization M(H) measurements. The results show on the weak antiferromagnetic coupling at low temperatures represented by the Weiss constant θ=-0.468 K. The value of effective magnetic moment μ_{eff}=7.57μ_{B}, which was estimated from the experimental data is close to the theoretical value for systems with S=7/2. Correlation between crystal structure of complexes and magnetic properties is presented.
19
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Shielding Behaviors and Analysis of Mechanical Treatment of Cements Containing Nanosized Powders

80%
Mutuk H., Mutuk T., Gümüş H., Mesci Oktay B.
Acta Physica Polonica A
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2016
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vol. 130
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issue 1
172-174
EN
In this study, we investigated linear attenuation coefficient (μ ), half value layer, tenth value layer at 243, 344, 866, 1088, 1112, 1528 keV. Mechanical properties of cements containing nanosized powders (nano-SiO₂, nano-Fe₂O₃, nano-Al₂O₃) are obtained. According to compressive strength results nano-SiO₂ added cementitious material gave the highest strength. Moreover, all the nanopowders added samples showed higher compressive strength with respect to reference sample. The experimental linear mass attenuation coefficients μ , half value layer, tenth value layer for cementitious material were compared with theoretical values obtained using XCOM. The experimental results were found to be in good agreement with the theoretical values.
20
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Porous Ceramic Supports for Membranes Prepared from Kaolin (DD3) and Calcite Mixtures

80%
Harabi A., Boudaira B., Bouzerara F., Foughali L., Zenikheri F., Guechi A., Ghouil B., Condom S.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1164-1166
EN
The supports for microfiltration (MF) and ultrafiltration (UF) were prepared with local kaolin (Djebel Debagh: type 3: DD3) and calcium carbonate (CaCO₃) mixtures. The choice of these materials is based on their natural abundance (low price). In this work, the tubular ceramic supports were prepared by the extrusion method. The sintering was carried out for 2 hours, at temperatures laying between 1150 and 1300°C. They are then characterized by various techniques: mercury porosimetry, scanning electron microscopy and x-ray diffraction. The obtained results revealed that the main phase formed during the sintering step was anorthite with a minor phase of mullite. Moreover, it has been found that supports sintered at temperatures less than 1300°C had interesting characteristics; an average pore size ranged between 3.91-8.56 μm, a porosity ratio of 42.0-50.4%, a flexural strength ≈67-77 MPa and the pore size distribution is bimodal type. According to their average pore sizes, they may be used either as supports for MF or UF membranes.
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