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Makaraviciute A.,Vilnius University | Ruzgas T.,Malmo University | Ramanavicius A.,Vilnius University | Ramanavicius A.,State Scientific Research Institute Center for Physical science and Technology | Ramanaviciene A.,Vilnius University
Key Engineering Materials | Year: 2014

An immunosensor is an analytical system consisting of specific immune system molecules coupled to a signal transducer. Immunosensor sensitivity depends on the type of immunorecognition ligands used, immobilization influence on their activity and orientation on the surface. Quartz crystal microbalance with dissipation (QCM-D) was employed to investigate the immobilization of antibodies against bovine leukemia virus antigen gp51 (gp51). Disulphide bridges of antibody hinge region were reduced chemically to yield two "half" antibody fragments (Frag-Ab), each having a single antigen binding site and free sulfhydryl groups that were used for immobilization. Frag-Ab were immobilized on planar gold and gold nanoparticle (AuNP) modified QCM-D sensor surfaces from initial solutions of different concentrations. Higher Frag-Ab surface density values were obtained on AuNP modified surfaces at all tested antibody concentrations. Frag-Ab/gp51 specific interaction was registered and it was determined that the highest sensitivity was exhibited by Frag-Ab immobilized at the lowest surface desities on both types of investigated surfaces. Specific gp51 interaction with Frag-Ab and non-specific binding to bovine serum albumin modified surfaces were compared by employing Δf/ΔD plots, which could serve as "fingerprints" of different processes. © (2014) Trans Tech Publications. Source


Kezionis A.,Vilnius University | Petrulionis D.,Vilnius University | Kazakevicius E.,Vilnius University | Kazlauskas S.,Vilnius University | And 2 more authors.
Electrochimica Acta | Year: 2016

Unique 2-electrode (100 mHz–10 GHz) and 4-electrode (100 mHz–2 MHz) impedance spectroscopy equipment enables investigation of the fine structure of oxygen ion conductive La2Mo2O9 (LMO) solid electrolytes ceramics’ impedance response in temperatures ranging from 300 to 950 K. Temperature dependencies of the electrical parameters show abrupt jumps associated with the α↔β-LMO phase transition, which is also detected by X-ray powder diffraction and differential scanning calorimetry analyses. Electrical relaxation phenomena are analyzed in terms of the relaxation time distribution function. Four different relaxation processes are identified and attributed to processes in the ceramics’ grains and grain boundary media. Detailed analysis of these processes reveals surprising findings about the nature of the α ↔ β-LMO phase transition, indicating that the abrupt change in LMO compound's resistivity is associated not only with a change in the relative volume of the different phases, but also with an alteration of the β-LMO phase itself; thus the α↔β-LMO phase transition is found to have properties of I and II order phase transitions. The methods applied in this paper could have wide application to the investigation of ionically conductive materials. © 2016 Elsevier Ltd Source


Makaraviciute A.,Vilnius University | Ruzgas T.,Malmo University | Ramanavicius A.,Vilnius University | Ramanavicius A.,State Scientific Research Institute Center for Physical science and Technology | Ramanaviciene A.,Vilnius University
Analytical Methods | Year: 2014

Immunosensors are bioaffinity sensors incorporating immune system molecules that are utilized for analyte recognition and signal transduction yielding a measurable signal upon analyte detection. A lot of effort has been made to optimize the immobilization matrix on the sensor surface since the outcome of the ligand immobilization procedure determines sensitivity, specificity and longevity of the developed immunosensor. In this work, antibodies against bovine leukemia virus antigen gp51 were chemically reduced to "half" antibody fragments that were later employed as recognition ligands. Antibody fragments at different concentrations were immobilized via thiolate bonds on planar gold and gold nanoparticle modified surfaces of a quartz crystal microbalance with dissipation sensor. Antibody fragment immobilization and interaction with antigen were investigated. Antibody fragment surface mass densities after the immobilization on planar gold and gold nanoparticle modified sensor surfaces were directly dependent on the initial antibody concentration. The highest analytical response was exhibited by antibody fragments immobilized at the smallest surface mass density on planar gold and gold nanoparticle modified surfaces. Bovine leukemia virus antigen gp51 interaction with antibody fragments was compared with non-specific gp51 interaction with bovine serum albumin on planar gold and gold nanoparticle modified surfaces by employing ΔD/Δf plots. This journal is © the Partner Organisations 2014. Source


Uglov V.V.,Belarusian State University | Uglov V.V.,Tomsk Polytechnic University | Abadias G.,University of Poitiers | Zlotski S.V.,Belarusian State University | And 5 more authors.
Journal of Surface Investigation | Year: 2015

The influence of ion irradiation (180-keV Xe2+ and doses of 1 × 1016 and 5 × 1016 cm–2) on the structure and phase composition of thin (300 nm) nanocrystalline (Ti,Zr)1–xSixNy films deposited via reactive magnetron sputtering (Si content x ≤ 0.22) is investigated. It is found that an increase in the Si concentration of the coating stimulates successive structure conversions from nanocrystalline (x < 0.07; grain size is about 18 nm) to nanocomposite (0.07 ≤ x ≤ 0.11; grain size is about 8 nm) and amorphous (x ≥ 0.18) states. The phase composition of the coatings varies from diphase (c-(Ti,Zr)N + a-TiSiNx) to amorphous (a-TiZrSiN). The nanocomposite coating consists of c-(Ti,Zr)N solid-solution grains (their size is ~8 nm) surrounded by an amorphous a-TiSiN matrix. Ion irradiation exerts no influence on the structural-phase state of the nanocrystalline and amorphous films. The diffraction peaks of the (Ti,Zr)N solid solution is revealed to be split because a double-layer structure is formed. This is associated with Xe-ion implantation into the coating. (Ti,Zr)N solid-solution grains are found to crystallize if amorphous coatings (0.18 ≤–≤ 0.22) are irradiated with xenon ions. © 2015, Pleiades Publishing, Ltd. Source


Abromavicius G.,State Scientific Research Institute Center for Physical science and Technology | Abromavicius G.,Optida Co Ltd | Buzelis R.,State Scientific Research Institute Center for Physical science and Technology | Drazdys R.,State Scientific Research Institute Center for Physical science and Technology | And 7 more authors.
Lithuanian Journal of Physics | Year: 2011

The nonlinear LBO (LiB 3O 5) crystal is widely used in many Nd: YAG, Yb: KGW and Nd: YLF lasers in order to generate higher optical harmonics. However, the most limiting factor in such applications is the optical resistance of their coated surfaces described by the so-called Laser Induced Damage Threshold (LIDT) parameter. In this work we investigate the "fatigue" (multi-pulse) behaviour of LIDTs in LBO crystals coated with different types of (single AR@355 nm and triple AR@355+532+1064 nm wavelength) anti-reflective coatings while optimising the refractive index designs and selecting appropriate sub-layer materials. All the coatings were produced of different oxide materials (ZrO 2, Al 2O 3, SiO 2) and ZrO 2-SiO 2 mixtures by using the ion beam sputtering (IBS) deposition technique. The optical damage resistance of both fixed and transient refractive index coatings is of special interest. Besides the spectral properties, the resistance to laser irradiation is characterized at the wavelength of 355 nm with laser pulses of nanosecond duration. The conclusions are drawn about the AR coated LBO with the most successful designs by the means of optical resistance. © lietuvos mokslu{ogonek} akademija, 2011. Source

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