Problems of the Protection of Traces of Classical Masonry on the Isle of Marmara (Proconnesus)

Information about the discovery and securing of marble objects in seven lapidaria on the island of Marmara Adasi, known in antiquity as Proconnesus. Despite certain gaps, a uniform policy is applied for the protection of the monuments. The exhibits are recorded in inventories, placed in temporary lapidaria, accessible and prepared for conservation. They comprise a permanent element of the lineage of material culture, harmoniously blended with the surrounding cultural-anthropogenic-natural environment

Incomplete Cross-Bonding in the MV Line. Experience from the Operation of MV Single Cable Lines

Cable lines are one of the basic components of power systems. Medium and high voltage cables mainly comprise a metallic sheath, which is concentric to the main core conductor. There are several operating schemes of such cable lines, which differ in the place of earthing of sheaths and the possible use of the sheaths and/or conductors crossing. The sheaths cross-bonding is typically done in two places of one cable line section, and it allows to reduce power losses. Nevertheless, the use of incomplete sheaths crossing—only in one place on cable route may have economic justification. The paper presents an incomplete sheaths cross-bonding analysis of an existing medium voltage cable line. The results obtained by the mathematical model are validated by measurements taken on 30 October 2019 on an existing cable line. Measurements recorded on a real object for various systems of crossing sheaths are presented. The influence of incorrect sheaths crossing on the measured quantities was shown. In addition, the risk of excess voltage on the sheaths during short-circuits has been verified using a mathematical model

Krzyżowanie żył powrotnych w liniach kablowych SN w celu zmniejszenia strat energii czynnej

Currently, almost all medium voltage cable lines (MV) operate with the return wires earthed at both ends of the cable. Such a way of operation causes that during normal states of operation as well as during disturbances, e.g. short-circuits, in the return wires induce currents whose values mainly depend on the currents flowing in the phase wires. These currents in normal operating states are a source of additional energy losses incurred in the MV cables. The effect can be decreased by the return wires cross-bonding or the phase wires transposition. The paper discusses the potential effects that can be achieved by use of the return wires cross-bonding or the phase wires transposition in the domestic grids.Aktualnie u prawie wszystkich polskich operatorów sieci dystrybucyjnej (OSD) linie kablowe średniego napięcia (SN) pracują z żyłami powrotnymi uziemionymi na początku i na końcu linii. Taki układ pracy powoduje, że podczas stanów normalnych, jak i podczas zwarć, indukują się w żyłach powrotnych prądy, których wartości zależą głównie od prądów płynących w żyłach roboczych. Prądy te w stanach normalnych są źródłem dodatkowych strat przesyłowych ponoszonych w kablach SN. Artykuł zawiera dyskusję nad zasadnością stosowania transpozycji żył powrotnych lub żył roboczych w warunkach krajowych

Disclosing Interfaces of ZnO Nanocrystals Using Dynamic Nuclear Polarization: Sol‐Gel versus Organometallic Approach

International audienceThe unambiguous characterization of the coordination chemistry of nanocrystal surfaces that have been produced by a wetchemical synthesis presently remains a highly challenging issue. Here, zinc oxide nanocrystals (ZnO NCs) coated by monoanionic diphenyl phosphate (DPP) ligands were derived by a traditional sol-gel process and a one-pot self-supporting organometallic (OSSOM) procedure, and advanced atomic-scale characterization through dynamic nuclear polarization (DNP-)enhanced solid-state nuclear magnetic resonance (ssNMR) spectroscopy has notably enabled resolving their vastly different surface-ligand interfaces. For the OSSOM-derived NCs, DPP moieties form stable and strongly-anchored µ2-and µ3-bridgingligand pairs that are resistant to competitive ligand exchange processes. Contrastingly, the sol-gel-derived NCs contain a wide variety of coordination modes of DPP ligands and a ligand exchange process takes place between DPP ligands and glycerol molecules. This highlights the power of DNP-enhanced ssNMR for detailed NC surface analysis and the superiority of the OSSOM approach for the preparation of high quality ZnO NCs

Structural Diversity of Ethylzinc Carboxylates

The synthesis and structural characterization of a new series of ethylzinc carboxylates are reported. Structurally diverse complexes were derived from three monofunctional carboxylic acids with different numbers of phenyl groups on the α-carbon, and two bifunctional carboxylic acids with a neutral donor terminus, namely, methoxyacetic and diethylphosphonoacetic acids. Donor solvents are commonly used in various transformations of alkylzinc carboxylates; therefore, the effect of THF as a donor solvent on the reaction outcome was also investigated. Reactions of equimolar amounts of Et₂Zn and the selected carboxylic acid in THF solutions gave ethylzinc carboxylates with a large variety of structures. In the cases of triphenylacetic and diphenylacetic acids, THF solvated products of stoichiometry [EtZn­(O₂CR)­(THF)] were isolated as a dimer and a 1D coordination polymer, respectively, whereas, with methoxyacetic acid, a novel solvent-free hexanuclear structural motif with a butterfly-like framework was formed, ([EtZnO₂­CCH₂OCH₃]₆). The corresponding reaction with diethylphosphonoacetic acid produced a rare example of a nonanuclear organozinc oxo carboxylate cluster, [(EtZn)₈Zn­(μ₃-O)₂­(O₂CCH₂(O)­P­(OEt)₆)]

Structural Diversity of Ethylzinc Carboxylates

The synthesis and structural characterization of a new series of ethylzinc carboxylates are reported. Structurally diverse complexes were derived from three monofunctional carboxylic acids with different numbers of phenyl groups on the α-carbon, and two bifunctional carboxylic acids with a neutral donor terminus, namely, methoxyacetic and diethylphosphonoacetic acids. Donor solvents are commonly used in various transformations of alkylzinc carboxylates; therefore, the effect of THF as a donor solvent on the reaction outcome was also investigated. Reactions of equimolar amounts of Et₂Zn and the selected carboxylic acid in THF solutions gave ethylzinc carboxylates with a large variety of structures. In the cases of triphenylacetic and diphenylacetic acids, THF solvated products of stoichiometry [EtZn­(O₂CR)­(THF)] were isolated as a dimer and a 1D coordination polymer, respectively, whereas, with methoxyacetic acid, a novel solvent-free hexanuclear structural motif with a butterfly-like framework was formed, ([EtZnO₂­CCH₂OCH₃]₆). The corresponding reaction with diethylphosphonoacetic acid produced a rare example of a nonanuclear organozinc oxo carboxylate cluster, [(EtZn)₈Zn­(μ₃-O)₂­(O₂CCH₂(O)­P­(OEt)₆)]

Structural Diversity of Ethylzinc Carboxylates

The synthesis and structural characterization of a new series of ethylzinc carboxylates are reported. Structurally diverse complexes were derived from three monofunctional carboxylic acids with different numbers of phenyl groups on the α-carbon, and two bifunctional carboxylic acids with a neutral donor terminus, namely, methoxyacetic and diethylphosphonoacetic acids. Donor solvents are commonly used in various transformations of alkylzinc carboxylates; therefore, the effect of THF as a donor solvent on the reaction outcome was also investigated. Reactions of equimolar amounts of Et₂Zn and the selected carboxylic acid in THF solutions gave ethylzinc carboxylates with a large variety of structures. In the cases of triphenylacetic and diphenylacetic acids, THF solvated products of stoichiometry [EtZn­(O₂CR)­(THF)] were isolated as a dimer and a 1D coordination polymer, respectively, whereas, with methoxyacetic acid, a novel solvent-free hexanuclear structural motif with a butterfly-like framework was formed, ([EtZnO₂­CCH₂OCH₃]₆). The corresponding reaction with diethylphosphonoacetic acid produced a rare example of a nonanuclear organozinc oxo carboxylate cluster, [(EtZn)₈Zn­(μ₃-O)₂­(O₂CCH₂(O)­P­(OEt)₆)]