EVALUATION OF THE SURFACE ENERGY OF SOLIDS USING TWO-COMPONENT MIXTURES OF TEST LIQUIDS

The design processes of composite materials require considering the surface energy of the phases. The choice of a series of test fluids to determine surface energy in the framework of the Zisman and Owens-Wendt models sometimes causes difficulties in the interaction of these fluids – dissolution or swelling of the substrate. The minimum number of test fluids is two, but more is used to increase accuracy. The use of mixed solvents allows to increase the number of experimental points, as well as to more accurately adjust the polarity of the medium, which is essential in determining the surface energy of substances that are unstable to the action of many solvents. The paper considered the possibility of using a mixture of a pair of test liquids that do not interact with the material and factors that may limit the accuracy of the determination. Also, on the example of stearic acid illustrates the process of determining surface energy by this method. Polypropylene and polycarbonate were chosen to determine the surface energy in the Owens-Wendt model. Test liquids used included water, ethylene glycol, dimethyl sulfoxide, ethanol, cyclohexane, glycerol and tetrahydrofuran. As a result, the use of a mixed solvent to determine the surface energy of polymers can increase the accuracy of the method by increasing the number of experimental points on the Owens-Wendt graph. Increase of the experimental points area, however, is limited to the points of individual solvents of the mixture, and the uncovered part of the graph needs to be corrected to reduce the error. It is shown that the use of only mixed solvents is inefficient due to the restriction of the zone of variability by the area between the coordinates of the individual solvents of the mixture. It has been shown that when determining the surface energy of materials that are not resistant to solvents, the accuracy can be increased by using mixed solvents, but this requires balancing the measurement range.

Alexandria Kom el-Dikka. Excavations and preservation work in the 2018 season

The 2018 season saw a continuation of research on Roman housing and urbanism in Alexandria. Excavations were focused in the central area of the Kom el-Dikka site, where some early to mid-Roman structures (2nd–3rd centuries AD) were explored. The uncovered part of the building seems to combine domestic and commercial functions. A couple of shops opening onto the street were identified. Evidence of artisanal production of glass beads was also recognised in the post-occupation phase. Post-processing of the finds (pottery, glass vessels, painted wall plaster and coins) was continued. The paper also brings an overview of the preservation program, which was limited this season to maintenance conservation of structures seriously threatened by unfavourable climatic conditions (mainly Baths and auditoria).

Could Stratospheric Ozone Depletion Make Hadley Cells Expand?

Convection-driven Hadley cells are expanding poleward. Scientists now may have uncovered part of the reason why.

THE EXCAVATION OF NON BAN JAK, NORTHEAST THAILAND - A REPORT ON THE FIRST THREE SEASONS

<p class="1Abstract"><span lang="EN-US">Non Ban Jak is a large, moated site located in the upper Mun Valley, Northeast Thailand. Excavations over three seasons in 2011-4 have revealed a sequence of occupation that covers the final stage of the local Iron Age. The site is enclosed by two broad moats and banks, and comprises an eastern and a western mound separated by a lower intervening area. The first season opened an 8 by 8 m square on the eastern mound, while the second and third seasons uncovered part of the low terrain rising into the western mound, encompassing an area of 25 by 10 m. The former revealed a sequence of industrial, residential and mortuary activity that involved the construction of houses, kiln firing of ceramic vessels and the interment of the dead within residences. The latter involved four phases of a late Iron Age cemetery, which again incorporated house floors and wall foundations, as well as further evidence for ceramic manufacture. The excavation sheds light on a late Iron Age town occupied at the threshold of state formation.</span></p>

MARKET CAPACITY FROM THE VIEWPOINT OF LOGISTIC ANALYSIS / RINKOS TALPA: LOGISTINĖS ANALIZĖS POŽIŪRIS

The paper discusses market potential and market capacity as a relevant problem of logistic analysis in economy. The emphasis is laid on the concept of market capacity which is comprehended as market potential (the other term occasionally referred to is, potential capital') and which is also the highest possible, from a theoretical viewpoint, amount of product/service sales that could be reached within a certain period of time by all the companies in the market. The paper focuses on the actually complete market (actually covered market) and on market niche (the uncovered part of markets). Studies show that from the viewpoint of logistic analysis, markets can be divided according to their closure. It has been established that according to the degree of closure a market can be open, close and intermediate. Possible scenarios of partly closed market formation have been studied. Results show that with the intensification of market closure, the economic system is essentially changing its behaviour. Santrauka Straipsnyje aptariamos rinkos potencialo ir rinkos talpos dimensijos kaip nūdienos ekonomikos problemų sprendimo galimybė logistines analizės požiūriu. Autoriai nagrinėja užpildytą (prisotintą) rinką (praktiškai aprėpta rinką) ir nišos rinką (neaprėpta rinkos dalį). Vertinant iš logistines analizės perspektyvos, rinkos gali būti skirstomos pagal jų uždarumą. Nustatyta, kad pagal uždarumo laipsnį rinka gali būti trejopa: atvira, uždara ir vidutiniškai uždara. Išnagrinėti galimi iš dalies uždaros rinkos formavimosi scenarijai. Tyrimo rezultatai rodo, kad intensyvėjant rinkos uždarumui ekonomikos sistema keičia savo elgseną.

Sprouting ability of aerial and underground dormant basal buds of Betulapendula

The effect of ground level on the bursting and development of primary basal buds, formation of secondary basal buds, and survival of sprouts was studied with 2-year-old pot plants of silver birch (Betulapendula Roth) in an experiment in which the ground level was changed. Both intact and decapitated seedlings were manipulated. Raising the ground level reduced the bursting of dormant basal buds, while lowering it promoted both the bursting of buds and survival of the sprouts, especially in the decapitated plants. Many new basal buds developed regardless of the ground level. The intact plants also formed secondary basal buds, but these mostly remained dormant, like old, primary buds. In addition, the concentration of new bud clusters in the uncovered part of the stem suggested that although the plant's internal condition is important for the development and bursting of its basal buds, environmental factors are also involved. Ground-level changes on drained mires and at afforestation sites may significantly affect the success of sprouting.

A Dark Age Cemetery in Erechtheion Street, Athens

In the spring of 1955 the Water Company, extending its drainage system to include Erechtheion Street, a road in the neighbourhood south of the Acropolis running south from the street of Dionysius the Areopagite, uncovered part of the wall and a gate of the ancient city. The Ephoria of Acropolis Antiquities under its then director, Mr. J. Miliades, undertook the excavation of these remains. With the aid of his epimelete, Dr. G. Dontas, the present director of the Acropolis, he cleared the wall and the gate down to bedrock, and extended his investigation to uncover as many building remains and other finds as possible, under a fair amount of pressure from the Water Company, who were in a hurry to begin their own work. The excavation, which took place from March until June 1955, has added considerably to our knowledge of the topography of the area during the classical period; at the same time it uncovered a Dark Age cemetery.

Excavations at Gloucester. Fourth Interim Report: St. Oswald's Priory, Gloucester, 1975–1976

SummaryExcavations at St. Oswald's Priory, Gloucester, showed that the site was occupied in the second century by the Roman municipal tile works which was abandoned by the fourth century. The ruined church which now stands on the site shows two successive building phases pre-dating a Norman arcade; excavation established part of the plan of this late Anglo-Saxon church and also uncovered part of the tenth- to thirteenth-century cemetery. Documentary evidence suggests that this was the ‘new minster’ built by Æthelflæd and Æthelred of Mercia. Taking other historical and archaeological evidence into consideration, Gloucester can be argued to have had, in the late ninth to early tenth century, a special significance for the rulers of Mercia.Specialist reports are offered on the stratified medieval pottery, and on the inscribed bell-mould from the tenth-century church.

Further Excavations at Aetos

After the close of Mr. Heurtley's excavations, an attack on the site by illicit diggers showed that the deposit had not been exhausted and that there were still fine vases (e.g. 1023, Plate 22) to be found there. Moreover, some of the conclusions drawn from the facts observed at Aetos merited further investigation.Date of Building 9: Bench mark for both excavations was the threshold of St. George's Church. Heurtley kindly allowed me to use some of his plans, so we uncovered part of Building 9, and were thus able to fit the plans of the two excavations together. I have included Building 9 on my plan (Fig. I ), also the ‘Cairns’ 1, 2, 4, and Wall 6. An undisturbed part of the foundation trench of Building 9 contained sherds of sixth-century Corinthian kotylai, so it cannot be the Protocorinthian temple as Heurtley suggested: no offerings were connected with it.

On the magnetizing power of the more refrangible solar rays

In the year 1813, Professor Morichini, of Rome, announced that steel exposed in a particular manner to the concentrated violet rays of the prismatic spectrum becomes magnetic. His experiments, however, having uniformly failed in other hands, had ceased to excite gene­ral attention; especially in this country, whose climate is usually so unfavourable for such researches. The unusual clearness of weather last summer, however, induced Mrs. Somerville to make the attempt. Having, at that time, no information of the manner in which Prof. Morichini’s experiments were conducted, it occurred to her, however, as unlikely that if the whole of a needle were equally exposed to the violet rays, the same influence should at the same time produce a south pole at one end, and a north at the other of it. She therefore covered half of a slender sewing needle, an inch long, with paper, and fixed it in such a manner as to expose the uncovered part to the vio­let rays of a spectrum, thrown by an equiangular prism of flint glass on a panel at five feet distance. As the place of the spectrum shifted, the needle was moved so as to keep the exposed part constantly in the violet ray. The sun being bright, in less than two hours the needle, which before the experiment showed no signs of polarity, had become magnetic; the exposed end attracting the south pole of a suspended magnetic needle, and repelling the north. No iron was near to disturb the experiment, which was repeated the same day, under similar circumstances, with a view to detect any source of fal­lacy in the first attempt, but with the same result. The season continuing favourable, afforded daily opportunities of repeating and varying the experiment. Needles of various sizes (all carefully ascertained to be free from polarity), and exposed in va­rious positions with regard to the magnetic dip and meridian, almost all became magnetic; some in a longer, some in a shorter time, va­rying from half an hour to four hours, but depending on circum­stances not apparent. The position of the needles seems to have had no influence, but the experiments were generally more success­ful from 10 to 12 or 1 o’clock than later in the day. The exposed portion of the needle became (with a few exceptions) a north pole, exceptions possibly attributable to some predisposition in the needle, itself to magnetism too slight to be observed. The distance of the needle from the prism was varied without materially varying the effect. It was found unnecessary to darken the room, provided the spectrum was thrown out of the direct solar rays.