Warsaw University of Technology

About: Warsaw University of Technology is a education organization based out in Warsaw, Poland. It is known for research contribution in the topics: Microstructure & Optical fiber. The organization has 14293 authors who have published 34362 publications receiving 492211 citations. The organization is also known as: Warsaw Polytechnic & Politechnika Warszawska.

Energy dependence and fluctuations of anisotropic flow in Pb-Pb collisions at √sNN = 5.02 and 2.76 TeV

Abstract: Measurements of anisotropic flow coefficients with two- and multi-particle cumulants for inclusive charged particles in Pb-Pb collisions at $ \sqrt{s_{\mathrm{NN}}}=5.02 $ and 2.76 TeV are reported in the pseudorapidity range |η| < 0.8 and transverse momentum 0.2 < p$_{T}$ < 50 GeV/c. The full data sample collected by the ALICE detector in 2015 (2010), corresponding to an integrated luminosity of 12.7 (2.0) μb$^{−1}$ in the centrality range 0-80%, is analysed. Flow coefficients up to the sixth flow harmonic (v$_{6}$) are reported and a detailed comparison among results at the two energies is carried out. The p$_{T}$ dependence of anisotropic flow coefficients and its evolution with respect to centrality and harmonic number n are investigated. An approximate power-law scaling of the form v$_{n}$(p$_{T}$) ∼ p$_{T}^{n}^{/3}$ is observed for all flow harmonics at low p$_{T}$ (0.2 < p$_{T}$ < 3 GeV/c). At the same time, the ratios v$_{n}$/v$_{m}^{n}^{/ }^{m}$ are observed to be essentially independent of p$_{T}$ for most centralities up to about p$_{T}$ = 10 GeV/c. Analysing the differences among higher-order cumulants of elliptic flow (v$_{2}$), which have different sensitivities to flow fluctuations, a measurement of the standardised skewness of the event-by-event v$_{2}$ distribution P(v$_{2}$) is reported and constraints on its higher moments are provided. The Elliptic Power distribution is used to parametrise P(v$_{2}$), extracting its parameters from fits to cumulants. The measurements are compared to different model predictions in order to discriminate among initial-state models and to constrain the temperature dependence of the shear viscosity to entropy-density ratio.

3D bioprinting of hydrogel constructs with cell and material gradients for the regeneration of full-thickness chondral defect using a microfluidic printing head.

Abstract: Osteochondral (OC) tissue is a biphasic material comprised of articular cartilage integrated atop subchondral bone. Damage to this tissue is highly problematic, owing to its intrinsic inability to regenerate functional tissue in response to trauma or disease. Further, the function of the tissue is largely conferred by its compartmentalized zonal microstructure and composition. Current clinical treatments fail to regenerate new tissue that recapitulates this zonal structure. Consequently, regenerated tissue often lacks long-term stability. To address this growing problem, we propose the development of tissue engineered biomaterials that mimic the zonal cartilage organization and extracellular matrix composition through the use of a microfluidic printing head bearing a mixing unit and incorporated into an extrusion-based bioprinter. The system is devised so that multiple bioinks can be delivered either individually or at the same time and rapidly mixed to the extrusion head, and finally deposited through a coaxial nozzle. This enables the deposition of either layers or continuous gradients of chemical, mechanical and biological cues and fabrication of scaffolds with very high shape fidelity and cell viability. Using such a system we bioprinted cell-laden hydrogel constructs recapitulating the layered structure of cartilage, namely, hyaline and calcified cartilage. The construct was assembled out of two bioinks specifically formulated to mimic the extracellular matrices present in the targeted tissues and to ensure the desired biological response of human bone marrow-derived mesenchymal stem cells and human articular chondrocytes. Homogeneous and gradient constructs were thoroughly characterized in vitro with respect to long-term cell viability and expression of hyaline and hypertrophic markers by means of real-time quantitative PCR and immunocytochemical staining. After 21 days of in vitro culture, we observed production of zone-specific matrix. The PCR analysis demonstrated upregulated expression of hypertrophic markers in the homogenous equivalent of calcified cartilage but not in the gradient heterogeneous construct. The regenerative potential was assessed in vivo in a rat model. The histological analysis of surgically damaged rat trochlea revealed beneficial effect of the bioprinted scaffolds on regeneration of OC defect when compared to untreated control.

Metal oxide sensor arrays for detection of explosives at sub-parts-per million concentration levels by the differential electronic nose

Abstract: The study presents an application of the differential electronic nose to the estimation and recognition of the TNT, PETN and RDX in the complex environments under their storage. Generally there are two separate problems in the field of recognition of explosives: first – detection of the trace concentration of explosives by analytical methods (gas chromatography, ion mobility spectrometry, neutron activation analysis) and the second – the estimation of the state of explosives during their time storages in the military objects. In the second problem the concentration of a vapor of explosives is at level of sub-parts-per million where chemosensors technique is fully applicable. This paper is concerned with the second type problem. It defines the recognition criteria providing stable and robust basis for the recognition of different explosive materials. The important part of this procedure performs the 2-dimensional convolution of the differential signals formed on the basis of two sensor arrays used in the construction of the differential nose. The experimental results of the recognition of TNT, PETN and RDX have confirmed the excellent recognition ability of the developed system.