The Adsorption of Small Molecules on the Copper Paddle-Wheel: Influence of the Multi-Reference Ground State

We report a theoretical study of the adsorption of a set of small molecules (C$_{2}$H$_{2}$, CO, CO$_{2}$, O$_{2}$, H$_{2}$O, CH$_{3}$OH, C$_{2}$H$_{5}$OH) on the metal centers of the “copper paddle-wheel”—a key structural motif of many MOFs. A systematic comparison between DFT of different rungs, single-reference post-HF methods (MP$_{2}$, SOS–MP$_{2}$, MP$_{3}$, DLPNO–CCSD(T)), and multi-reference approaches (CASSCF, DCD–CAS(2), NEVPT2) is performed in order to find a methodology that correctly describes the complicated electronic structure of paddle-wheel structure together with a reasonable description of non-covalent interactions. Apart from comparison with literature data (experimental values wherever possible), benchmark calculations with DLPNO–MR–CCSD were also performed. Despite tested methods show qualitative agreement in the majority of cases, we showed and discussed reasons for quantitative differences as well as more fundamental problems of specific case

Crown structure of Picea omorika trees in the plantation

The study was carried out in Serbian spruce (Picea omorika Panč/Purkynĕ) plantations in the western Serbia. The paper presents results of the analysis of crown development. The following elements were analyzed: total tree height, height of the crown base, absolute and relative crown length, maximal crown diameter, coefficient of crown spreading and degree of crown girth. We discuss approaches to the modeling of tree crown growth and development, growing under favorable environmental and stand conditions, without anomalies in development. In order to establish the relationship between analyzed factors, regression analyses were applied. Data fitting was by the analytic method, by the implementation of Prodan’s functions of growth, linear and parabolic function. Received models can be used for the simulation of various growth and developing processes in forest

Identifikacija virusa infektivnih za običnu tikvu (Cucurbita pepo L.) u Jugoslaviji

This study was carried out in order to identify the major viruses infecting pumpkins (Cucurbita pepo)grown in Serbia. Leaf samples from virus-infected pumpkin plants were collected in mid-July 2001. Naked-seeded and hulled oil pumpkins, patty pan, zucchini and summer squash from three different locations were included (Table 1). Virus-infected plants showed different symptoms (Table 2 and Figures 1-4). Due to the great variability of the symptoms, the causal viruses could not be fully and precisely determined by visual examination only. The infected samples were tested by the biotest, as well as by two serological methods, ELISA and EBIA. Polyclonal antibodies raised against cucumber mosaic cucumovirus (CMV), zucchini yellow mosaic potyvirus (ZYMV), watermelon mosaic potyvirus 1 (WMV-1), watermelon mosaic potyvirus 2 (WMV-2) and squash mosaic comovirus (SqMV) were used. In each of the 50 collected samples one or two viruses were detected (Tables 3 and 4). The most prevalent viruses infecting pumpkins were ZYMV (62%) and CMV (58%). WMV-2 was extremely rare.Cilj ovih istraživanja bio je da se identifikuju najvažniji virusi tikava (Cucurbita pepo L) gajenih u Srbiji. Uzorci biljnog materijala uljane tikve-golice, uljane tikve sa ljuskom, tikvice za jelo, patisona i cukinija koji su bili zaraženi virusima, sakupljeni su u tri lokaliteta sredinom jula 2001. godine (tab. 1). Biljke zaražene virusima pokazivale su različite simptome (tab. 2 i sl. 1-4). Tačna determinacija virusa samo na osnovu simptoma nije moguća zbog varijabilnosti samih simptoma. Zaraženi uzorci su testirani biotestom kao i primenom dve serološke metode, ELISA i EBIA korišćenjem poliklonalnih antitela na Cucumber mosaic cucomovirus (CMV) Zucchini yellow mosaic potyvirus (ZYMV), Watermelon mosaic potyvirus 2 (WMV-2), Watermelon mosaic potyvirus 1 (WMV-1) i Squash mosaic comovirus (SqMV). U 50 ispitanih uzoraka detektovan je jedan ili dva virusa (tab. 3 i 4). Preovlađujući virusi tikava bili su ZYMV (62%) i CMV (58%). WMV-2 je detektovan u veoma malom broju uzoraka

Biološka i serološka karakterizacija virusa tikvica u Jugoslaviji

A survey on summer squash open field crops was carried out during 2000 and 2001 in order to identify the major viruses infecting these crops in different localities. Plants showed different types of symptoms: mild mosaic, chlorotic spotting, distinctive mosaic, blistering of leaf lamina leaf yellowing, deformation of leaf lamina, knobbed fruits and stunting of plants. The symptoms were very variable but showed the viral nature of the investigated summer squash diseases. The collected samples were tested by bioassay and by two serological methods ELISA and EBIA using cucumber mosaic cucumovirus (CMV), zucchini yellow mosaic potyvirus (ZYMV), watermelon mosaic potyvirus 2 (WMV-2), zucchini yellow flack potyvirus (ZYFV) watermelon mosaic potyvirus 1 (WMV-1), squash mosaic comovirus (SqMV) and cucurbit aphid-borne yellows polerovirus (CABYV) polyclonal antisera. In all tested samples single or mixed infection with ZYMV, CMV and WMV-2 was detected. The most prevalent virus infecting summer squash was ZYMV. This is the first report of ZYMV, the most destructive virus infecting cucurbits, in Yugoslavia. It was also proven that the identified viruses are transmissible by Aphis gossypii in a non-persistent manner, but possible role of seed in virus transmission was not confirmed.U toku 2000. i 2001. godine izvršen je pregled useva tikvica za jelo da bi se identifikovali osnovni virusi infektivni za tikvice u različitim lokalitetima. Biljke su pokazivale različite simptome: blagi mozaik hlorotičnu pegavost, izraženi mozaik, klobučavost liske, žućenje lista deformacije liske, bradavičaste izraštaje na plodu i kržljavost biljaka. Simptomi su veoma varijabilni i na osnovu njih se ne može obaviti determinacija virusa prouzrokovača oboljenja. Sakupljeni uzorci su testirani biotestom, kao i sa dve serološke metode, ELISA i EBIA korišćenjem poliklonalnih antiseruma na cucumber mosaic cucumovirus (CMV), zucchini yellow mosaic potyvirus (ZYMV), watermelon mosaic potyvirus 2 (WMV-2) zucchini yellow flack potyvirus (ZYFV), watermelon mosaic potyvirus 1 (WMV-1), squash mosaic comovirus (SqMV) i cucurbit aphid-borne yellows polerovirus (CABYV). U svim ispitivanim uzorcima dokazana je pojedinačna ili mešana infekcija sa ZYMV, WMV-2 i CMV. Najčešće infekcije su bile sa ZYMV. Ovaj virus, jedan od najdestruktivnijih virusa na vrežastim kulturama, prvi put je konstatovan u našoj zemlji. Takođe je utvrđeno da se identifikovani virusi prenose na neperzistentan način vašima Aphis gossypii, a moguća uloga semena u pojavi oboljenja nije potvrđena

Uticaj oblika i strukture čestica na tečljivost elektrolitičkog bakarnog praha II - eksperimentalna potvrda modela reprezentativne čestice praha

An analysis of the effects of the shape, surface structure and size distribution of particles on the flow ability of the copper powder was performed. It is shown that the most important property of the particles of a powder, regarding the flow ability of the powder, is the surface structure of the particles.Izvedena je analiza uticaja oblika, površinske strukture i raspodele veličina čestica na tečljivost bakarnog praha. Pokazano je da površinska struktura predstavlja najvažnije svojstvo čestice praha u odnosu na njegovu tečljivost

Selection of the most appropriate welding technology for hardfacing of bucket teeth

A possibility of extending the service life of the working parts of construction machinery with particular attention to hardfacing of loader bucket teeth was investigated. In the first part of this paper the tribological processes typical for this machinery is analysed. Worn excavator parts are made of conditionally weldable cast steel that requires a special hardfacing technology, so numerous investigations were performed to obtain the most appropriate technology. In the experimental part of the paper, the selection of the optimum hardfacing technology for bucket teeth and the procedure of the manual arc hardfacing are presented. The samples were first hardfaced using different techniques and technologies and then the microstructure and microhardness of characteristic hardfaced layers were studied. Specially prepared samples were used for tribological investigations. The results of experimental investigations enabled the selection of the most suitable hardfacing technology and its application to real parts. The bucket teeth, with their hardfaced layers applied vertically, horizontally or in a honeycomb pattern were mounted onto a loader bucket, alternated with the new non-hardfaced teeth and their performance during the operation was regularly monitored. After a certain period, the degrees of the wear for the non-hardfaced and differently hardfaced teeth were measured. Taking into account both technical and economic factors, the most suitable hardfacing technology was determined

Selection of the most appropriate welding technology for hardfacing of bucket teeth

A possibility of extending the service life of the working parts of construction machinery with particular attention to hardfacing of loader bucket teeth was investigated. In the first part of this paper the tribological processes typical for this machinery is analysed. Worn excavator parts are made of conditionally weldable cast steel that requires a special hardfacing technology, so numerous investigations were performed to obtain the most appropriate technology. In the experimental part of the paper, the selection of the optimum hardfacing technology for bucket teeth and the procedure of the manual arc hardfacing are presented. The samples were first hardfaced using different techniques and technologies and then the microstructure and microhardness of characteristic hardfaced layers were studied. Specially prepared samples were used for tribological investigations. The results of experimental investigations enabled the selection of the most suitable hardfacing technology and its application to real parts. The bucket teeth, with their hardfaced layers applied vertically, horizontally or in a honeycomb pattern were mounted onto a loader bucket, alternated with the new non-hardfaced teeth and their performance during the operation was regularly monitored. After a certain period, the degrees of the wear for the non-hardfaced and differently hardfaced teeth were measured. Taking into account both technical and economic factors, the most suitable hardfacing technology was determined

Energetic analysis of hard facing and weld cladding of an air powered drop hammer damaged ram

This paper studies problems of hard facing of damaged and initially cracked mechanical engineering heavy parts of complex geometry such as large rams of air powered drop hammers. During long-term exploitation, these parts are subjected to thermal fatigue due to cyclic temperature changes and variable impact compression. Taking into consideration high ram costs and difficulties to purchase ram, the necessity of its reparation becomes obvious. The choices of the most suitable technologies of hard facing and welding of an initially cracked ram are also studied here. Besides the techno-economic analysis, an energetic analysis is performed as an additional criterion in assessment of the proposed technology