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The dynamics of the activity and selectivity of bifunctional platinum tungstated zirconia PtWZ catalyst in the hydroisomerization of n-heptane and heptane–benzene mixture is discussed in the paper. The change in the properties of the catalyst before and after reaction were characterized using different techniques. The catalyst showed high efficiency for the hydroisomerization of heptane and heptane–benzene mixture, however, deactivation occurred with time on stream, more significantly when benzene was present in the reaction mixture. The carbonaceous matter was deposited on the catalyst (up to 0.8%) during the hydroisomerization reaction. Predominantly aliphatic carbonaceous «poly-CxHy» species, much less oxidized and little aromatic «graphite-like» species were identified by XPS spectra on the catalyst after the heptane isomerization. In the presence of benzene, the formation of «graphite-like» matter increased progressively as temperature increased. However, no appreciable changes in the bulk properties of the t-ZrO2 matrix (phase composition, specific surface area, pore volume, pore size distribution) and in the state of platinum component were revealed, though an increased extent of W6+ to W5+ reduction was detected by XPS spectra irrespectively of the reaction conditions. The deactivation of the PtWZ catalyst was suggested to result from the blocking the active centers by carbonaceous deposits, the deactivation of the acidic centers being more pronounced as compared to metallic ones. All the carbonaceous deposits were burned-off completely below 450–500 °C.Graphical Abstract

The dynamics of the activity and selectivity of bifunctional platinum tungstated zirconia PtWZ catalyst in the hydroisomerization of n-heptane and heptane–benzene mixture is discussed in the paper. The change in the properties of the catalyst before and after reaction were characterized using different techniques. The catalyst showed high efficiency for the hydroisomerization of heptane and heptane–benzene mixture, however, deactivation occurred with time on stream, more significantly when benzene was present in the reaction mixture. The carbonaceous matter was deposited on the catalyst (up to 0.8%) during the hydroisomerization reaction. Predominantly aliphatic carbonaceous «poly-C x H y » species, much less oxidized and little aromatic «graphite-like» species were identified by XPS spectra on the catalyst after the heptane isomerization. In the presence of benzene, the formation of «graphite-like» matter increased progressively as temperature increased. However, no appreciable changes in the bulk properties of the t -ZrO 2 matrix (phase composition, specific surface area, pore volume, pore size distribution) and in the state of platinum component were revealed, though an increased extent of W 6+ to W 5+ reduction was detected by XPS spectra irrespectively of the reaction conditions. The deactivation of the PtWZ catalyst was suggested to result from the blocking the active centers by carbonaceous deposits, the deactivation of the acidic centers being more pronounced as compared to metallic ones. All the carbonaceous deposits were burned-off completely below 450–500 °C. Graphical Abstract

The dynamics of the activity and selectivity of bifunctional platinum tungstated zirconia PtWZ catalyst in the hydroisomerization of n-heptane and heptane-benzene mixture is discussed in the paper. The change in the properties of the catalyst before and after reaction were characterized using different techniques. The catalyst showed high efficiency for the hydroisomerization of heptane and heptane-benzene mixture, however, deactivation occurred with time on stream, more significantly when benzene was present in the reaction mixture. The carbonaceous matter was deposited on the catalyst (up to 0.8%) during the hydroisomerization reaction. Predominantly aliphatic carbonaceous \"poly-C.sub.xH.sub.y\" species, much less oxidized and little aromatic \"graphite-like\" species were identified by XPS spectra on the catalyst after the heptane isomerization. In the presence of benzene, the formation of \"graphite-like\" matter increased progressively as temperature increased. However, no appreciable changes in the bulk properties of the t-ZrO.sub.2 matrix (phase composition, specific surface area, pore volume, pore size distribution) and in the state of platinum component were revealed, though an increased extent of W.sup.6+ to W.sup.5+ reduction was detected by XPS spectra irrespectively of the reaction conditions. The deactivation of the PtWZ catalyst was suggested to result from the blocking the active centers by carbonaceous deposits, the deactivation of the acidic centers being more pronounced as compared to metallic ones. All the carbonaceous deposits were burned-off completely below 450-500 °C.

The physicochemical properties of the partially spent catalyst Pt-Re-Cl/Al^sub 2^O^sub 3^ reforming of petroleum fractions (R-98 UOP) have been studied. It has been found that during operation of the catalyst, a reduction of textural characteristics, chemical composition, partial phase transformation of alumina support, and accumulation of metallic impurities and carbon deposits take place. The DSC method has been found the presence on the surface of the catalyst of various types of carbonaceous deposits burnable at different temperatures. Their removal is complete at temperatures 500-550 °C.

SnO2 is a promising material for electro- and photocatalysis sensors. In the electrocatalysis field, SnO2 is able to serve as a stable catalyst support for PEMFC cathodes. In this work, SnO2 were synthesized using SnCl4 or SnC2O4 and polystyrene microspheres as a template. The materials were characterized by XRD spectroscopy, CHNS analysis, low temperature (77 K) N2 adsorption, mercury intrusion porosimetry (MIP) and SEM. The SnC2O4 decomposition resulted in obtaining SnO2 with high conductivity up to 0.275 S/cm according to impedance spectroscopy. The increase in aging time and PS loading improves SnO2 conductivity and stability. The potential cycling test in 1.0–1.5 V RHE range revealed that stability of the most stable SnO2 is higher than that of CB Ketjen Black EC-300J and comparable with that of Vulcan XC-72R. The ORR activities of Pt catalyst based on macroporous SnO2 showed values similar to those of Pt/SnO2 found in literature.

The Proteus syndrome affects some tissues and not others and is thought to be caused by a somatic mutation. Investigators found that the mutation is caused by activation of AKT1, an enzyme that mediates glucose metabolism, cell proliferation, and apoptosis. The Proteus syndrome is characterized by patchy or segmental overgrowth and hyperplasia of multiple tissues and organs, along with susceptibility to the development of tumors 1 , 2 (Figure 1). It is thought that Joseph Merrick, an Englishman who lived in the late 19th century and became the subject of the play and film The Elephant Man, had the Proteus syndrome. This uncommon syndrome (with an incidence of <1 case per 1 million population) has not been reported to recur in a family but has been reported in discordant monozygotic twins. 3 These observations support the hypothesis that the Proteus syndrome is caused . . .

The demarcation of the chemical elements into metals and non-metals dates back to the dawn of Dmitri Mendeleev's construction of the periodic table; it still represents the cornerstone of our view of modern chemistry. In this contribution, a particular emphasis will be attached to the question ‘Why do the chemical elements of the periodic table exist either as metals or non-metals under ambient conditions?’ This is perhaps most apparent in the p-block of the periodic table where one sees an almost-diagonal line separating metals and non-metals. The first searching, quantum-mechanical considerations of this question were put forward by Hund in 1934. Interestingly, the very first discussion of the problem—in fact, a pre-quantum-mechanical approach—was made earlier, by Goldhammer in 1913 and Herzfeld in 1927. Their simple rationalization, in terms of atomic properties which confer metallic or non-metallic status to elements across the periodic table, leads to what is commonly called the Goldhammer–Herzfeld criterion for metallization. For a variety of undoubtedly complex reasons, the Goldhammer–Herzfeld theory lay dormant for close to half a century. However, since that time the criterion has been repeatedly applied, with great success, to many systems and materials exhibiting non-metal to metal transitions in order to predict, and understand, the precise conditions for metallization. Here, we review the application of Goldhammer–Herzfeld theory to the question of the metallic versus non-metallic status of chemical elements within the periodic system. A link between that theory and the work of Sir Nevill Mott on the metal-non-metal transition is also highlighted. The application of the ‘simple’, but highly effective Goldhammer–Herzfeld and Mott criteria, reveal when a chemical element of the periodic table will behave as a metal, and when it will behave as a non-metal. The success of these different, but converging approaches, lends weight to the idea of a simple, universal criterion for rationalizing the instantly-recognizable structure of the periodic table where … the metals are here, the non-metals are there … The challenge of the metallic and non-metallic states of oxides is also briefly introduced. This article is part of the theme issue ‘Mendeleev and the periodic table’.

The study is the first to examine the combined use of blast-furnace sludge as a source of microelements and converter slag as a soil-deoxidizing agent in oat (Avena sativa L.) cultivation in sod-podzolic soils. It has been established that blast-furnace sludge is a highly dispersed waste, which contains about 50% iron, 7% zinc, and a small amount of calcium, silicon, magnesium, aluminum, and sulfur. Hazardous components such as lead, arsenic, etc., are not detected. Converter slag comprises porous granules up to 3 mm in size, consisting mainly of calcium compounds (CaO, Ca(CO)3, CaSiO3, CaFe2O4) and a small amount of Mn, Al, and Mg trace elements. In a laboratory experiment, blast-furnace sludge increased the germination of oats by 5–10%, regardless of the addition of a deoxidizer (slag), but at the same time suppressed the growth of stem length by a maximum of 18% at 1 g∙kg−1. The addition of slag raised substrate pH and increased the index by 8% at a sludge concentration of 0.1 g∙kg−1. Root length in deoxidizer-free variants increased by 50–60% and with the addition of slag by 27–47%. Root dry mass also increased under the addition of sludge by 85–98%; however, the addition of slag reduced the indicator to the control level. In a field experiment with the combined application of waste, an increase in yield by more than 30% was shown. When soil was treated with slag and sludge, the height of plants increased by an average of 18%. It should be noted that the introduction of waste did not affect the quality of the grain. The use of slag increased the lead content in the soil, which is probably due to the sorption properties of calcium compounds in the slag, since lead was not found in the analyzed waste. Presumably, lead is sorbed by slag from the lower soil horizons, concentrating and immobilizing it in the upper layer. This version is supported by the absence of lead accumulation in straw and oat grain. The zinc-containing sludge increased the content of this element by 33% in the soil, as well as by 6% in straw and by 14% in grain. Thus, we found that the studied metallurgical wastes can be used as nutrients for agriculture, both individually and jointly. Overall, the proposed approach will contribute both to reducing the amount of accumulated waste and to improving the efficiency and sustainability of agricultural production and CO2 sequestration. However, the features of the accumulation of heavy metals in soil and plants under the influence of the analyzed types of waste require more in-depth study, including within the framework of long-term field experiments.

Blast furnace slag is a key large-tonnage waste product of metallurgical production, which is considered to be a promising alternative material in construction. In order to determine the scope of potential use of slag as a marketable product, it is necessary to study its structure and composition, which is determined by means of modern analytical instrumental methods. This paper analyzes the application of Fourier transform infrared spectroscopy (FTIR) and chemometrics methods to develop calibration models for identifying pelletized slag by elemental composition. In a comparative analysis of FTIR-spectra of slag the characteristic frequencies of absorption bands responsible for the content of calcite, silicates and aluminosilicates in the composition of samples were determined. Multivariate regression methods (principal components regression, partial least squares regression) and data of elemental composition results by EDX method were used to develop calibration models for determining elemental composition of granulated blast furnace slag. Using the developed PLS models with high performance (R2 from 0.91 to 0.96 for different components), the prediction of the elemental composition (Ca, Si, O, Mg) of the test sample was carried out and a low deviation of the prediction in contrast to the EDX reference data was obtained. The use of PLS calibration models for rapid and nondestructive determination of the quantitative content of components of the composition of granulated blast furnace slag has been proposed.

The demarcation of the chemical elements into metals and non-metals dates back to the dawn of Dmitri Mendeleev’s construction of the periodic table; it still represents the cornerstone of our view of modern chemistry. In this contribution, a particular emphasis will be attached to the question ‘Why do the chemical elements of the periodic table exist either as metals or non-metals under ambient conditions?’ This is perhaps most apparent in the p-block of the periodic table where one sees an almost-diagonal line separating metals and non-metals. The first searching, quantum-mechanical considerations of this question were put forward by Hund in 1934. Interestingly, the very first discussion of the problem—in fact, a prequantum- mechanical approach—was made earlier, by Goldhammer in 1913 and Herzfeld in 1927. Their simple rationalization, in terms of atomic properties which confer metallic or non-metallic status to elements across the periodic table, leads to what is commonly called the Goldhammer–Herzfeld criterion for metallization. For a variety of undoubtedly complex reasons, the Goldhammer–Herzfeld theory lay dormant for close to half a century. However, since that time the criterion has been repeatedly applied, with great success, to many systems and materials exhibiting non-metal to metal transitions in order to predict, and understand, the precise conditions for metallization. Here, we review the application of Goldhammer–Herzfeld theory to the question of the metallic versus non-metallic status of chemical elements within the periodic system. A link between that theory and the work of Sir Nevill Mott on the metal-non-metal transition is also highlighted. The application of the ‘simple’, but highly effective Goldhammer–Herzfeld and Mott criteria, reveal when a chemical element of the periodic table will behave as a metal, and when it will behave as a non-metal. The success of these different, but converging approaches, lends weight to the idea of a simple, universal criterion for rationalizing the instantly-recognizable structure of the periodic table where ...the metals are here, the non-metals are there ...The challenge of the metallic and non-metallic states of oxides is also briefly introduced. This article is part of the theme issue ‘Mendeleev and the periodic table’.