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Number of results: 7
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Abstract

Depending on the clinical context, objectives, and treatment requirements, a variety of prosthetic devices capable of artificially reconstructing the dental arches in a manner as customized as possible can be utilized in the treatment of complete edentation. The purpose of this study is to compare the efficacy of general vitamin B12 treatment vs the efficacy of local treatment accomplished through full dentures. The study was performed on a group of patients of Dental Faculty in Iasi.Because cyanocobalamin deficiency is typically treated parenterally, the current study proved the superiority of local treatment with complete dentures obtained through the crosslinked polymerization method, a much easier and less expensive way to perform the same treatment in the same time period.
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Authors and Affiliations

Dana Gabriela Budală
1
ORCID: ORCID
Dragos Ioan Virvescu
1
ORCID: ORCID
Elena-Raluca Baciu
1
ORCID: ORCID
Paweł J. Pietrusiewicz
2
ORCID: ORCID
Roxana Ionela Vasluianu
1
ORCID: ORCID
Dragos Nicolae Frățilă
1
ORCID: ORCID

  1. University of Medicine and Pharmacy Gr.T. Popa, Faculty of Dental Medicine, Iasi, Romania
  2. Czestochowa University of Technology Faculty of Production Engineering and Materials Technology, Department of Physics, 42-200 Częstochowa, Poland
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Abstract

Graphitic carbon nitride (g-C3N4) is an attractive photocatalyst, however, its practical photocatalytic applications are still faced with huge challenges. The aim of this research is to identify the correlation between synthetic conditions and properties of the g-C3N4 and derive an optimum synthesis condition for improving photocatalytic activities of the g-C3N4. In this study, novel and versatile g-C3N4 nanosheets were synthesized by the simple thermal pyrolysis of urea. In the synthesis process, the pyrolysis temperature and the heating rate, which can have the most significant influence on the structures and properties of g-C3N4, were set as variables, and the effects were systematically investigated. When synthesized at a relatively high temperature, the amount of material being synthesized is reduced, however it has been found to represent optical properties suitable for highly efficient photocatalyst by the increase in the thickness and defects formed in the g-C3N4 nanosheets. The photocatalytic degradation experiment of MB dyes indicated that the highest degradation of 95.2% after the reaction for 120 min was achieved on the g-C3N4 nanosheets synthesized at 650oC.

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Authors and Affiliations

Jeong Hyun Kim
ORCID: ORCID
Myeongjun Ji
ORCID: ORCID
Cheol-Hui Ryu
Young-In Lee
ORCID: ORCID
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Abstract

Propagation of linearly polarized light beams in a nematic liquid crystal cell with distinguished regions of different molecular orientation has been analyzed. Specifically, combination of the planar/homogenic and homeotropic alignment, forming thus spatially limited regions characterized by a different LC molecular orientation, has been tested, as achieved by means of the photo-orientation and photo-polymerization processes, independently. An influence of molecular orientation on the light beam propagation has been checked for different directions of the linear polarization. Thanks to the molecular reorientation induced by the low frequency external electric field and also to the reorientational nonlinearity taking place in NLCs, propagation direction of the light beam can be additionally controlled by the electric bias and/or optical power, respectively. Proposed structural solutions and techniques, related to the photo-orientation and photo-polymerization processes described in this communication, give rise to the novel LC geometries and structures. The latter act as promising candidates for new practical photonic applications as they are expected to be of a particular importance for integrated optic elements and devices.

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Authors and Affiliations

K.A. Rutkowska
M. Chychłowski
M. Kwaśny
I. Ostromęcka
J. Piłka
U.A. Laudyn
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Abstract

The main goal of the present study was to examine the operating characteristics and mechanisms of membrane fouling in integrated membrane bioreactors (IMBRs) at diff erent temperatures. Two IMBRs, each with identical dimensions and confi gurations, were used in the study using synthetic domestic sewage at a low temperature (10°C) and high temperature (25°C). The results indicated that the removal effi ciency of chemical oxygen demand reached 93–96%, but the membrane contribution rate of IMBR2 (10°C) was higher than that of IMBR1 (25°C). The separation burden of the membrane on organic compounds increased at low temperature, which may have sped up the rate of membrane biofouling. The absolute rate of trans-membrane pressure build-up was faster at low temperature, leading to shorter IMBR operating times. Soluble microbial products (SMPs) and extracellular polymeric substances (EPSs) in the IMBRs signifi cantly increased at low temperature. These substances intensifi ed defl occulation, with an accompanying reduction of fl oc size and the release of EPSs at low temperature, which facilitated the formation of cake foulants on the surface, covering the entire membrane area. The protein and polysaccharide concentrations of SMPs and EPSs in the IMBRs were correlated with the concentration of C8-HSL. It was demonstrated that temperature aff ected the concentration of C8-HSL, which controlled the excretion of EPSs and SMPs and thus the membrane biofouling process.

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Authors and Affiliations

Yaqin Yu
1

  1. Department of Civil Engineering, Yancheng Institute of Technology, China
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Abstract

The paper contains a description of the geometry of Beveloid gears. It describes the distribution of forces in a Beveloid gear with a straight tooth line and a helical tooth line. The paper presents research on the experimentally determined parameters of transmission operation, including the sound pressure level and the amount of heat emitted during operation. The design and construction of the test stand were presented. The research methodology was described. Operational tests are carried out on household appliances with Beveloid gears: Grinder and Jam mixer. Thanks to an appropriately selected narrowing angle, estimated values of service life extension of the above-mentioned transmissions are given.
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Bibliography

  1. S. Beermann, “Estimation of lifetime for plastic gears,” Fall Technical Meeting of the American Gear Manufacturers Association, Detroit, Michigan, Oct. 2007, pp. 1‒17.
  2.  R. Keresztes, L. Zsidai, G. Kalácska, and P. De Baets, “Friction of polymer/steel gear pairs,” Scientific Bulletin of North University of Baia Mare, serie C, vol. XXIII, pp. 63–72, Jan. 2009.
  3.  P. Strojny, “Wpływ kąta zwężenia kół zębatych typu Beveloid na płynność przeniesienia napędu w przekładniach zębatych z tworzyw polimerowych,” Przegląd Mechaniczny, no. 6, Jun. 2016, [in Polish].
  4.  N. Agbetossou, A. Afio, K. Attipou, D. Koffi, K. Kassegne, and S. Tiem, “Modeling and Prediction of Wear for Gears in Plastic Materials and Their Composites,” Int. J. Eng. Res. Technol., vol.  9, no. 7, pp. 90–106, Jul. 2020.
  5.  A.J Muminovic, M. Colic, E. Mesic, and I. Saric, “Innovative design of spur gear tooth with infill structure,” Bull. Pol. Acad. Sci. Tech. Sci., vol. 68, no. 3, pp. 477–483, 2020.
  6.  N.B. Thamba et al., “Study of Effect of Linear Tip Relief Modification in Power Transmission Efficiency of Spur Gears,” Arch. Acoust., vol. 45, no. 2, pp. 271–282, 2020.
  7.  G. Yu, H. Liu, K. Mao, C. Zhy and Z. Lu, “Examination on the wear process of polyformaldehyde gears under dry and lubricated conditions,” Friction, vol. 9, pp. 538–550, Jan. 2020.
  8.  Flir, [Online]. Available: www.flir.com (accessed Feb. 12, 2021).
  9.  A. Gebhardt, Rapid Prototyping, Carl Hanser Verlag GmbH & Co. KG, Munich, 2003.
  10.  W.F. Liu, Rapid Prototyping and engineering applications – a toolbox for prototype development, Taylor & Francis Group, Boca Raton, USA, 2008.
  11.  R.E. Śliwa, G. Budzik, J. Bernaczek, and T. Dziubek, “The rapid Prototyping of aircraft wheel hub model with the use of techniques JS, SLA, FDM,” J. KONES Powertrain Transp., vol. 18,pp.  439–443, Mar. 2011.
  12.  T. Singh, S. Kumar, and S. Sehgal, “3D printing of engineering materials: A state of the art review,” Mater. Today Proc., vol. 28, no. 3, pp. 1927‒1931, 2020.
  13.  N.B. Thamba et al., “Fault Analysis of Worm Gear Box Using Symlets Wavelet,” Arch. Acoust., vol 45, no. 3, pp. 521–540, 2020.
  14.  A. Hamrol, J. Gawlik, and J. Sładek, “Mechanical engineering in Industry 4.0,” Manag. Prod. Eng. Rev., vol. 10, pp.  14–28, Sep. 2019.
  15.  Dupont. [Online]. Available: www.dupont.com (accessed Feb. 10, 2021).
  16.  J.F. Rabek, “Współczesna wiedza o polimerach,” Tom 1. Budowa strukturalna polimerów i metody badawcze, PWN, Warszawa, 2017 [in Polish].
  17.  M. Sobolak and P. Strojny, “Effect of the narrowing angle in beveliod gear on the temperature profile on the active flank of tooth,” Adv. Sci. Technol. Res. J., vol. 7, pp. 67–69, Dec. 2013.
  18.  M. Płocica and A. Marciniec, Methodology of Preparing Hypoid Gears for Vibroacoustic Diagnostics in Laboratory Conditions, Oficyna Wydawnicza Politechniki Warszawskiej, Warszawa, 2018.
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Authors and Affiliations

Piotr Strojny
1

  1. The Faculty of Mechanical Engineering and Aeronautics, Rzeszow University of Technology, al. Powstańców Warszawy 12, 35-959 Rzeszów, Poland
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Abstract

An optimum route to synthesis the W-based composite powders with homogeneous dispersion of oxide nanoparticles was investigated. The La2O3 dispersed W powder was synthesized by ultrasonic spray pyrolysis using ammonium metatungstate hydrate and lanthanum nitrate. The dispersion of Y2O3 nanoparticles in W- La2O3 powder was carried out by a polymer addition solution method using yttrium nitrate. XPS and TEM analyses for the composite powder showed that the nano-sized La2O3 and Y2O3 particles were well distributed in W powder. This study suggests that the combination processing of ultrasonic spray pyrolysis and polymeric additive solution is a promising way to synthesis W-based composite powders.
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Authors and Affiliations

Youn Ji Heo
1 2
ORCID: ORCID
Eui Seon Lee
1
ORCID: ORCID
Jeong Hyun Kim
1
ORCID: ORCID
Young-In Lee
1 2
ORCID: ORCID
Young-Keun Jeong
3
ORCID: ORCID
Sung-Tag Oh
1 2
ORCID: ORCID

  1. Seoul National University of Science and Technology, Department of Materials Science and Engineering, Seoul 01811, Republic of Korea
  2. Seoul National University of Science and Technology, The Institute of Powder Technology, Seoul 01811, Republic of Korea
  3. Pusan National University, Graduate School of Convergence Science, Busan 46241, Republic of Korea
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Abstract

A novel herbicidal controlled release formulation composed of (2,4-dichlorophenoxy) acetic acid (2,4-D) chemically bonded to biodegradable (R,S)-3-hydroxybutyric acid oligomers was investigated. The synthesis of (R,S)-3-hydroxy butyric acid oligomers was carried out via the ring opening polymerization of β-butyrolactone initiated by 2,4-dichlorophenoxy acetic potassium salt in the presence of complexing agents. The formed oligomers were characterized by size exclusion chromatography, proton magnetic resonance and electrospray mass spectrometry in order to fi nd out their molar mass distribution and molecular structures. An assessment of biological effectiveness of the obtained herbicidal formulation was carried out in the greenhouse vs. Sinapis alba var. Nakielska. A promotion of the controlled release formulation with decreased water solubility and with low vapor pressure of the active ingredient, instead of traditional formulations of 2,4-dichlorophenoxy acetic acid may help to ensure a greater safety for workers and reduce the risk of dissemination of the active ingredient in the soil profi le.
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Authors and Affiliations

Witold J. Kowalski
Iwona Romanowska
Marzena Smol
Andrzej Silowiecki
Mariola Głazek

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