Search results for "Thermal"

Degradation of Antibiotic Vancomycin by UV Photolysis and Pulsed Corona Discharge Combined with Extrinsic Oxidants

2023

Antibiotics are the most frequently detected pharmaceuticals in the environment creating conditions for the development of resistant genes in bacteria. Degradation and mineralization of glycopeptide antibiotic vancomycin (VMN) were examined by UV photolysis, pulsed corona discharge (PCD), and their combinations with extrinsic oxidants, hydrogen peroxide (HP), peroxydisulfate (PDS), and peroxymonosulfate (PMS). Both combinations were effective in VMN degradation and faster at pH 11 than in acidic or neutral media. Combined with the UV photolysis, HP showed a higher oxidation rate than other oxidants, whereas PMS and PDS proved to be more efficient in combinations with PCD. In contrast to low…

Clay Nanotube/PNIPAAM Hybrid material

2014

Heat capacity and thermal conductivity of multiferroics Bi1-xPrxFeO3

2019

The heat capacity and thermal conductivity of multiferroics Bi1–xPrxFeO3 (0 ≤ x ≤ 0.50) has been studied in the temperature range of 130–800 K. A slight substitution of praseodymium for bismuth is found to lead to a noticeable shift of the antiferromagnetic phase transition temperature whilst the heat capacity increases. The temperature dependences of the heat capacity and thermal conductivity exhibit additional anomalies during phase transitions. The experimental results suggest that the excess heat capacity can be attributed to the Schottky effect for three-level states. The basic mechanisms of the heat transfer of phonons are highlighted and the dependence of the mean free path on temper…

Low temperature heat capacity of phononic crystal membranes

2016

Phononic crystal (PnC) membranes are a promising solution to improve sensitivity of bolometric sensor devices operating at low temperatures. Previous work has concentrated only on tuning thermal conductance, but significant changes to the heat capacity are also expected due to the modification of the phonon modes. Here, we calculate the area-specific heat capacity for thin (37.5 - 300 nm) silicon and silicon nitride PnC membranes with cylindrical hole patterns of varying period, in the temperature range 1 - 350 mK. We compare the results to two- and three-dimensional Debye models, as the 3D Debye model is known to give an accurate estimate for the low-temperature heat capacity of a bulk sam…

Approach to equilibrium of a quarkonium in a quark-gluon plasma

2018

We derive equations of motion for the reduced density matrix of a heavy quarkonium in contact with a quark-gluon plasma in thermal equilibrium. These equations allow in particular a proper treatment of the regime when the temperature of the plasma is comparable to the binding energy of the quarkonium. These equations are used to study how the quarkonium approaches equilibrium with the plasma, and we discuss the corresponding entropy increase, or free energy decrease, depending on the temperature regime. The effect of collisions can be accounted for by the generalization of the imaginary potential introduced in previous studies, and from which collision rates are derived. An important outcom…

Conduction properties of thin films from a water soluble carbon nanotube/hemicellulose complex.

2018

We have examined the conductive properties of carbon nanotube based thin films, which were prepared via dispersion in water by non-covalent functionalization of the nanotubes with xylan, a type of hemicellulose. Measurements of low temperature conductivity, Kelvin probe force microscopy, and high frequency (THz) conductivity elucidated the intra-tube and inter-tube charge transport processes in this material. The measurements show excellent conductive properties of the as prepared thin films, with bulk conductivity up to 2000 S cm−1. The transport results demonstrate that the hemicellulose does not seriously interfere with the inter-tube conductance. peerReviewed

Reduction and catalytic behaviour of heterobimetallic copper–lanthanide oxides

2008

Abstract The reduction of the heterobimetallic copper–lanthanide oxides 2CuO·CeO2 and 3CuO·Ln2CuO4 (Ln = La, Pr, Nd) was studied by H2-TG/DTA and H2-TPR. All systems exhibit two main reduction steps accompanied by mass losses in the temperature range 20–1000 °C. The first step was attributed to CuO reduction, whereas the second step is due either to copper reduction in the Ln2CuO4 phase with the concomitant formation of Ln2O3 or to the surface reduction of CeO2. The products were characterized by XRD, SEM, EDX, and BET techniques and are better described as supported copper type materials. They were active for the mesityl oxide (4-methyl-2-penten-2-one) gas phase hydrogenation.

Contributo alla conoscenza delle proprietà termofisiche delle murature storiche palermitane

2014

This paper presents the preliminary findings of in situ measurements of thermal transmittance taken in a monumental complex in Palermo. The objective of energy efficiency, one of the main aspects of sustainable construction, is now relevant also for historic architecture. The research aims at analysing the energy performance of the stone walls of the complex, characterized by various thickness, age and construction features. Measurements are taken in accordance with the international standard ISO 9869:1994. The U-values so obtained are compared with tabular data from the Italian standard UNI/TS 11300-1:2008 and with values calculated following the UNI EN ISO 6946:2008. Nine preliminary meas…

Biomass Waste Processing into Artificial Humic Substances

2021

Abstract To address the biomass waste processing problem and transform it into refractory forms of carbon, recently suggested hydrothermal carbonization (HTC) of biomass in alkaline environment can be considered as a prospective and climate neutral approach. Biomass HTC provides possibilities to obtain form of biochar (hydrochar) and artificial humic substances, however the conditions of the HTC have not been much studied. Optimization by Response Surface Methodology of the HTC using microwave treatment with three experimental variables (treatment temperature, length of microwave treatment, amount of biomass per volume) provides the possibility to significantly increase the yield of humic s…

Hydrothermal liquefaction of sewage sludge: towards the effects of transition metals in the presence of homogeneous hydrogen producers

2022

Waste carbonaceous matrices, such as sewage sludge (SS) seem to have a great potential, because they are namely costless matrices compared to the microalgae and hydrothermal liquefaction (HTL) can be considered an interesting route to dispose and valorize them [1-5]. However, SS are characterized by high amount of non-biogenic fractions, such as plastics, salts and metals. In particular SS contains a high amount of inorganics [5], such as Al, Ba, Ca, Cr, Cu, Fe, Ni, K, Mg, Mn, Na, P, S, Ti, Zn, Si which are distributed in the products at the end of the reaction. The presence of heavy metals represent a big challenge for the implementation of HTL on the industrial scale as they can affect pr…