Two novel isostructural coordination compounds of manganese(II) (1) and iron(II) (2) with common formulae MII(NCS)2(nia)2(OH2)2 have been prepared from water solution of appropriate metal salt, ...nicotinamide and KSCN. Their crystal structures were determined by means of X-ray diffraction on single crystals. The mononuclear title compounds crystallize in a triclinic P-1 space group with six monodentate octahedrally arranged ligands around the metal centre. The coordination molecules are self-assembled with an extended network of hydrogen bonds into a three-dimensional structure. Additionally, 1 and 2 were characterized with infrared spectroscopy, magnetic measurements and thermal analysis.
As a requirement for plant life extension for more than 40 years, additional Cable Aging Management Program (CAMP) has to be implemented in Nuclear Power Plant Krško. Samples of cables are selected ...based on nuclear safety and electrical equipment criticality for inspection and testing, to check functionality and prevent unexpected failure during normal operation. Different onsite testing equipment and methods are implemented to find harsh environment due to temperature, radiation, humidity and chemical effects that could affect insulation lifetime. Infrared thermography is used for determining and evaluating temperature hot spots.
The article presents a development of laboratory testing of cable insulation using Differential Scanning Calorimetry (DSC). Thirty-six samples of different nuclear qualified cables made of most frequently used materials, ethylene propylene rubber (EPR) and cross linked polyethylene (XLPE) – all with chlorosulfonated polyethylene (CSPE) jacket, were tested. Samples were 35 years old and additionally temperature aged in several steps with an intention to get acceptance criteria. Similar tests were conducted in two testing laboratories.
The results showed an evident decrease in oxidation stability of the inner EPR insulation; the onset temperature of oxidation processes has been shifted from 238 °C (unaged samples) to 175 °C (most aged samples). A decrease in oxidation stability was also observed for XPLE insulation; the onset oxidation temperature decreased from 266 °C for unaged samples to 213 °C (most aged samples). For the jacket material CSPE used as the insulation protection nearly no changes were observed.
Thermal treatment is one of environmental friendly wood modification processes, developed in order to improve wood’s natural durability and dimensional stability. Beside wood species, mainly ...isothermal temperature of heat-treatment and process duration affect these properties, which also correlate with the mass losses caused by the treatment. However, there is a lack of suitable external quality control methods. In this work thermogravimetry as a potential method for determining the degree of thermal modification is presented. Several calibration curves, representing the mass losses in a certain temperature range (the values obtained from the TG curves) compared to weight losses caused by previous heat-treatment (known values), were established for spruce wood samples modified at different isothermal temperatures (from 170 to 220 °C). Linear plot and good correlation factors (
R
2
= 0.95 and 0.96) were obtained for the TG mass losses from 130 to 280 °C and from 130 to 300 °C, both under nitrogen atmosphere. The predominant cause of mass loss in this temperature region was depolymerisation and thermal decomposition of hemicelluloses residues. Lower correlation factors were obtained under the air atmosphere and in the wider temperature range, respectively.
α-MnO2-type single-crystal nanorods were synthesized under hydrothermal conditions based on the redox reaction of KMnO4 in an acidic environment. Several reaction parameters, like the reaction ...temperature, the reaction time and the concentration of KMnO4 in the reaction mixture, were varied in order to determine their impact on the structure, the dimensions of the synthesized nanorods, and as well on their thermogravimetric properties. It was found that the reaction time has no significant influence on the diameter, although it has a strong influence on the length of the obtained nanorods. On the other hand, the concentration of KMnO4 in the reaction mixture has a strong impact on both the diameter and the length. With an increasing concentration of KMnO4 in the reaction mixture the average lengths and diameters of the isolated MnO2 nanorods are reduced. The change in dimensions of the synthesized nanorods is reflected in their thermogravimetric properties.
Due to its advantageous properties, titanium dioxide has been one of the most researched metal oxides and extensively used in various fields, including photocatalysis. Metal (platinum) and non‐metal ...(sulfur, nitrogen) doped titania thin films were prepared via a particular sol‐gel synthesis, coated onto object glasses and then thermally treated to promote TiO2 crystallization. Until now, photocatalytic activity of titania thin films has mostly been measured with different spectroscopic techniques (IR, UV‐Vis and fluorescence spectroscopy). The aim of the work presented in this article was to find alternative, non‐spectroscopic methods for photocatalytic activity measurements. To achieve this, we performed in‐situ UV‐Vis absorption spectra, conductivity (κ) and pH measurements during photocatalytic degradation of Plasmocorinth B under UV light illumination. Results have shown that there exists a linear correlation between changes in conductivity (Δκ), pH (ΔpH) values and photocatalytic activity of the samples, measured with UV‐Vis spectroscopy.
The aim of the work presented in this article was to find alternative, non‐spectroscopic methods for photocatalytic activity measurements. To achieve this, we performed in‐situ UV‐Vis absorption spectra, conductivity (κ) and pH measurements during photocatalytic degradation of Plasmocorinth B under UV light illumination. Results have shown that there exists a linear correlation between changes in conductivity (Δκ), pH (ΔpH) values and photocatalytic activity of the samples, measured with UV‐Vis spectroscopy.
Many interesting cathode materials, such as LiFePO
4, LiMnPO
4, LiFeBO
3 or the recently discovered Li
2FeSiO
4 and Li
2MnSiO
4, exhibit extremely low electronic conductivity (<10
−9
S
cm
−1). A very ...efficient way for improving the electronic transport in such materials is supposed to be the preparation of carbon coatings around individual active particles. Despite the increasing number of reports on preparation of various carbon coatings, neither the formation mechanism nor the detailed coating properties have been explained satisfactorily. The present paper is an attempt to find a clear correlation between the synthesis parameters, the resulting coating morphology and, finally, its electrical properties. As a substrate material for deposition of coatings, more or less monodisperse TiO
2 particles in various sizes were used. As a carbon precursor, citrate was used because it had given excellent results in our previous investigation of the LiFePO
4 system. It is shown that citrate precursor delivers pretty good conductivity (ca. 30
S
cm
−1) after a 10
h heat treatment at 700
°C or higher. The conductivity percolation threshold can be reached already at 1.5
vol.% of carbon, while the plateau conductivity of the whole composite is about 0.1
S
cm
−1. At that level, the carbon phase is supposed to form a well-distributed 3D electrical network within the composite.
We have synthesized large quantities of sodium-titanate-based nanotubes and nanoribbons with high yields under hydrothermal conditions from anatase powder in an aqueous NaOH solution. The reaction ...temperatures were from 95 to 195 degrees C, in steps of 20 degrees C. We observed that the morphology of the nanomaterials, which is reflected in their specific surface areas, depends strongly on the reaction temperature. For the materials synthesized in the range 95-135 degrees C and above 155 degrees C only a single morphology type was observed for the nanostructures, i.e., nanotubes and nanoribbons, respectively. In contrast, when the reaction was carried out at 155 degreesC, both nanotubes and nanoribbons were found in the product. SEM, TEM, and XRD techniques were used to determine the materials' morphological and structural properties, and the thermal stability of the materials was investigated with TGA and DSC. The largest weight loss, of approximately 25%, was observed in a temperature range from 25 up to 600 degrees C for the product obtained at 95 degrees C, probably due to the presence of unrolled titanate sheets.
The influence of pressure on the polycondensation reaction between novolac resin (N) present in commercially available moulding compounds and hexamethylenetetramine (HMTA) was studied up to 80 bars ...under air and in an inert atmosphere. For a low HMTA content (N/HMTA=98/2 mass ratio) high pressure enables the detection of two successive curing reactions. With increasing HMTA content the peak due to the first curing reaction becomes less pronounced at high pressure, while the enthalpy of the second increases. In an inert atmosphere both curing reactions are well observable even at ambient pressure and for lower HMTA content take place at lower temperatures, as expected. For the sample with N/HMTA=98/2 the curing reaction was followed using TG-MS.
Solar-powered photocatalysis has come a long way since its humble beginnings in the 1990s, producing more than a thousand research papers per year over the past decade. In this review, immobilized ...photocatalysts operating under sunlight are highlighted. First, a literature review of solar-driven films is presented, along with some fundamental operational differences in relation to reactions involving suspended nanoparticles. Common strategies for achieving sunlight activity from films are then described, including doping, surface grafting, semiconductor coupling, and defect engineering. Synthetic routes to fabricate photocatalytically active films are briefly reviewed, followed by the important factors that determine solar photocatalysis efficiency, such as film thickness and structure. Finally, some important and specific characterization methods for films are described. This review shows that there are two main challenges in the study of photocatalytic materials in the form of (thin) films. First, the production of stable and efficient solar-driven films is still a challenge that requires an integrated approach from synthesis to characterization. The second is the difficulty in properly characterizing films. In any case, the research community needs to address these, as solar-driven photocatalytic films represent a viable option for sustainable air and water purification.
CeOsub.2-TiOsub.2 is an important mixed oxide due to its catalytic properties, particularly in heterogeneous photocatalysis. This study presents a straightforward method to obtain 1D TiOsub.2 ...nanostructures decorated with CeOsub.2 nanoparticles at the surface. As the precursor, we used Hsub.2Tisub.3Osub.7 nanoribbons prepared from sodium titanate nanoribbons by ion exchange. Two cerium sources with an oxidation state of +3 and +4 were used to obtain mixed oxides. HAADF–STEM mapping of the Cesup.4+-modified nanoribbons revealed a thin continuous layer at the surface of the Hsub.2Tisub.3Osub.7 nanoribbons, while Cesup.3+ cerium ions intercalated partially between the titanate layers. The phase composition and morphology changes were monitored during calcination between 620 °C and 960 °C. Thermal treatment led to the formation of CeOsub.2 nanoparticles on the surface of the TiOsub.2 nanoribbons, whose size increased with the calcination temperature. The use of Cesup.4+ raised the temperature required for converting Hsub.2Tisub.3Osub.7 to TiOsub.2-B by approximately 200 °C, and the temperature for the formation of anatase. For the Cesup.3+ batch, the presence of cerium inhibited the conversion to rutile. Analysis of cerium oxidation states revealed the existence of both +4 and +3 in all calcined samples, regardless of the initial cerium oxidation state.
![[MII(NCS)2(nia)2(OH2)2]: Pr...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1318-0207/small "[MII(NCS)2(nia)2(OH2)2]: Preparation, Crystal Structure and Thermal Properties (MII = Mn, Fe; nia = nicotinamide)")
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