Large Number Of Fragments Research Articles

HREM Studies of Some Phases in the ZrO2-Nb2O5 System

High resolution electron microscopy and x ray powder diffraction techniques were used to study samples of various compositions in the Nb2O5-rich part of the ZrO2-Nb2O5 system at 1500°C. A large number of fragments were also characterized by electron diffraction in combination with EDS analysis. Some HREM results concerning block structures formed in the above region have previously been reported.The x ray powder pattern of a ZrO2.9Nb2O5 sample indicated a phase isotypic with T-Nb2O5. The micrograph in Fig. 1, of a thin crystal fragment from that sample, illustrates a phase related to the UVO5 (m=2) structure type. The electron diffraction patterns showed an ordered commensurate phase (m=8) with unit cell dimensions similar to those reported for T-Nb2O5 and Ta30W2O81. The structure models of these two compounds are rather similar and differ mainly in the oxygen content.

A Stochastic Programming Approach To The Estimation Of Shell Fragmentation Distributions

AbstractUpon detonation, a shell shatters into a large number of fragments. The characteristics of the fragmentation can be expressed using a joint distribution of three properties of the fragments, i.e. velocity, mass and the polar angle of projection. The conventional method of estimating this distribution was to build a thick plywood wall in a half-circle. This “arena” was taken down and dissected after each series of experiments. In addition to being expensive, the technique gave rather imprecise results. In this article, we present a new experimental method of estimation using test equipment consisting of metal containers called “collectors” and Doppler type radars which are not destroyed by the analysis. The data obtained from this equipment allows us to write the estimation problem in the form of a stochastic program with simple recourse into which the entropy related to this random experiment is introduced. With a validation technique based on simulation, we are able to show that this new method o...

Visibility of gallstone fragments at US and fluoroscopy: implications for monitoring gallstone lithotripsy.

To assess the value of ultrasound (US), fluoroscopy, and spot radiography in the detection, counting, and measurement of gallstone fragments during lithotripsy, in vitro visibility studies were conducted on fragments from 20 stones. Fluoroscopic visibility was evaluated during and after lithotripsy on 185 fragments placed in an anthropomorphic phantom. Three US experiments were performed on the fragments to study the visibility of fragments as a function of size, the accuracy of the count with large numbers of fragments, and the ability of observers to detect and count fragments larger than both 4 mm and 5 mm. With fluoroscopy, fragment detection rates ranged from 20% (fragments larger than 2.5 mm) to 80% (fragments larger than 4.5 mm). With US, all fragments larger than 1.5 mm were detected, and US was significantly better than fluoroscopy and spot radiography for detection of fragments 2.5 mm or smaller. US was also more accurate than fluoroscopy (11% vs 59% error) in the assessment of the number of fragments. When fragments larger than 4 mm or 5 mm were being counted with US, 92% of the fragments were visualized. The results suggest that US is more accurate for monitoring gallstone lithotripsy than fluoroscopy or spot radiography.

Characterization of the mitochondrial porin from Drosophila melanogaster

Mitochondrial porin was isolated from the fruit fly Drosophila melanogaster at different developmental stages, starting from whole mitochondria. The porin from adults' mitochondria was fully characterized. The protein had a molecular mass of 31 kDa as judged from sodium dodecylsulfate electrophoretograms. It was very resistive against digestion with V8 proteinase of Staphylococcus aureus and a larger number of fragments were only obtained after digestion with papain. Drosophila porin showed little interaction with antibodies raised against mitochondrial porins from mammalia and Neurospora crassa, but a strong reactivity with antibodies raised against yeast porin. Reconstitution experiments with planar lipid bilayer membranes showed that the protein was able to form ion-permeable pores with a single-channel conductance of 0.41 nS in 0.1 M KCl. At low transmembrane voltages Drosophila porin had the properties of a general diffusion pore with an estimated effective diameter of about 1.7 nm and a small selectivity for anions over cations. Voltages larger than 20 to 30 mV resulted in a closure of the pore. The closed states of the pore were found to be cation-selective. The addition of a synthetic polyanion to the aqueous phase on one side of the membrane resulted in an asymmetric shift of the voltage dependence and the pore became already closed at very small voltages negative at the cis-side (the side of the addition of the polyanion).

Intercalative binding of ditercalinium to d(CpGpCpG)2: a theoretical study.

The structure of the complex formed between ditercalinium, 2,2'-[4,4'-bipiperidine-1,1'-bis-(ethane-1,2-diyl)]bis(10-me thoxy-7H- pyrido[4,3-c]carbazolium) tetramethane sulfonate (NSC 366241), and the self-complementary tetranucleotide duplex d(CpGpCpG)2 has been investigated by means of a novel theoretical approach for modelling the conformational flexibility of nucleic acids. The methodology used is the JUMNA procedure, a molecular mechanics systematics capable of evaluating the internal energy and the interaction energy of a complex formed from a large number of fragments. In the best energy-minimized structures, the piperidinium chains of ditercalinium are located in the major groove of the right-handed oligonucleotide. Calculations show a distortion of the base-paired d(CpGpCpG)2 minihelix consisting of lateral dislocation of one base pair with respect to another along an axis parallel to the long axis; strong propeller twist and tilt of the end base pairs; a collective motion of all base pairs with respect to the helical axis towards the drug; and an overwinding at the exclusion site. The proposed structure of the complex is in good agreement with reported proton NMR data, supporting the feasibility of such model.

Restriction of single-stranded M13 DNA using synthetic oligonucleotides: the structural requirement of restriction enzymes.

A targeted ss (single stranded) DNA cleavage technique is reported which involves the use of synthetic oligomers complementary to the ss M13 DNA polylinker. BamHI, SmaI, and KpnI restriction enzymes were tested with a partial duplex DNA formed from ss M13 DNA and a nested series of fragments derived from a synthetic 21-mer which were complementary to the polylinker region. These enzymes require up to two flanking nucleotides in addition to the hexameric recognition site for efficient cleavage. This technique could be useful for effecting unique cleavages of DNA with enzymes which generally give a large number of fragments and for strategies of ss DNA manipulation.

Most of the murine leukemia virus sequences in the DNA of NIH/swiss mice consist of two closely related proviruses, each repeated several times.

The structure of the endogenous murine leukemia virus (MuLV) sequences of NIH/Swiss mice was analyzed by restriction endonuclease digestion, gel electrophoresis, and hybridization to an MuLV nucleic acid probe. Digestion of mouse DNA with certain restriction endonucleases revealed two classes of fragments. A large number of fragments (about 30) were present at a relatively low concentration, indicating that each derived from a sequence present once in the mouse genome. A smaller number of fragments (one to five) were present at a much higher concentration and must have resulted from sequences present multiple times in the mouse genome. These results indicated that the endogenous MuLV sequences represent a family of dispersed repetitive sequences. Hybridization of these same digested mouse DNAs to nucleic acid probes representing different portions of the MuLV genome allowed construction of a map of the sites where restriction endonucleases cleave the endogenous MuLV sequences. Several independent recombinant DNA clones of endogenous MuLV sequences have been isolated from C3H mice (Roblin et al., J. Virol. 43:113-126, 1982). Analysis of these sequences shows that they have the structure of MuLV proviruses. The sites at which restriction endonucleases cleave within these proviruses appeared to be similar or identical to the sites at which these nucleases cleaved within the MuLV sequences of NIH/Swiss mice. This identity was confirmed by parallel electrophoresis. We conclude that the apparently complex pattern of endogenous MuLV sequences of NIH/Swiss mice consists largely of only two kinds of provirus, each repeated multiple times at dispersed sites in the mouse genome.

Notes from the Babylonian Collection, II: Old Babylonian HAR-ra

The late Edgar J. Banks, source of so many collections of cuneiform tablets throughout the United States, left a considerable number of clay cones and tablets to his widow at his death in 1945. When it became known to me in 1970 that she was anxious to dispose of them, contact was quickly made with her and with her daughter, Mrs. James McLachlan. Over a thousand tablets thus came into the possession of the Yale Babylonian Collection, where most of them are now accessioned among the numbers 15339-16384. Subsequently a large number of fragments were turned over to the Collection by the Banks family; these remain to be accessioned. The cones were also examined, but as they all proved to be duplicates of familiar examples of Lagash and Old Babylonian royal inscriptions, only a representative sample was retained (now YBC 16435-16445) and the rest were returned to the family and disposed of elsewhere. Among the tablets thus newly accessioned, by far the majority were neoSumerian archival texts from Umma and PuzrwiT-Dagan (Drehem), with a sprinkling of earlier or later date. But here and there some canonical texts were identified in the group, for example, Inanna and Ebih lines 121-32 (YBC 16037). In some ways the most interesting of these isolated texts is YBC 16317, presented here in copy and transliteration.

Transformation of substrate specificity of EcoRl restrictase by glycerol

In the presence of glycerol, EcoRl restriction endonuclease hydrolyzes DNA into a larger number of fragments than under ordinary conditions. On the addition of glycerol to 50% concentration, this enzyme begins to act by what is called the “EcoRl' type” of restriction, which was producible experimentally only by reducing the ionic strength and increasing the pH of the solution. However, under these extremal conditions, the enzyme is quickly inactivated and does not give reproducible results, especially during the hydrolysis of high-molecular-weight DNA. The conditions found for manifestation of “EcoRl' activity” yield reproductible results, which is essentially equivalent to the discovery of a new “restriction endonuclease”.

Simultane instrumentelle Multielementbestimmung in antiker Keramik (Terra Sigillata) durch Aktivierungsanalyse mit hochenergetischen Photonen

A large number of fragments of ancient roman pottery has been analyzed for main constituents, minor and trace-elements using high-energetic photon activation analysis followed by high resolution gamma spectroscopy. Especially the environmental influence on the concentrations of the minor constituents and trace elements during deposition of the sherds in the soil has been examined. Finally, a comparison has been made between analysis data of ancient pottery obtained by photon activation analysis, X-ray fluorescence analysis and 14 MeV-neutron activation analysis.

Location of the cistron of the tobacco mosaic virus coat protein

Treatment of tobacco mosaic virus (TMV) RNA with T1 RNase under mild conditions cuts the RNA molecule into a large number of fragments, only a few of which may be specifically recognized by disks of TMV protein. It has been shown elsewhere that these specifically recognized RNA fragments are a part of the coat protein cistron, the portion coding for amino acids 95 to 129 of the coat protein. It is reported that different size classes of partially uncoated virus particles were prepared by limited reconstitution between TMV RNA and protein or by partial stripping of intact virus with DMSO. Both procedures produce nucleoprotein rods in which the 5'-terminal portion of the RNA is encapsidated and the 3'-terminal region is free. The free and the encapsidated portions of the RNA were each tested for the ability to give rise to the aforesaid specifically recognized fragments of the coat protein cistron upon partial T1 RNase digestion. It was found that only the 3'-terminal third of the virus particle need to be uncoated in order to expose the portion of the RNA molecule from which these fragments are derived. We conclude, therefore, that the coat protein cistron is situated upon the 3'-terminal third of the RNA chain, i.e. within 2000 nucleotides of the 3'-end.

Stucco Decoration in Pre-Augustan Italy

Fifty years ago, when Miss E. L. Wadsworth (Mrs. H. F. Cleland) wrote her monograph on Roman stucco reliefs, still the basic study of the subject, the earliest decorations that she examined in detail were those of a house discovered in the grounds of the Villa Farnesina in Rome. These stuccoes, which have been dated (with a precision perhaps unduly optimistic) to 19 B.C., are generally acknowledged to be among the masterpieces of their medium. From the vaults of three small cubicula come a large number of fragments showing a system of long borders and interlocking rectilinear panels, all framed by shallow mouldings and containing reliefs of great delicacy, of which the most important are landscapes, Dionysiac scenes, Victories, busts, grotesques and floral motifs (cf. Fig. 7, p. 52 and Plates I, a; II, a and b). Unpublished pieces of stucco-work from other vaults in the house repeat the same formula; and all attest the presence of artists of consummate skill and of an art-form which is technically perfect.Such work represents the culmination of a development, rather than its beginning. Miss Wadsworth was of course aware of this: indeed, she knew of at least one earlier set of decorations, the stuccoes of the Casa dei Grifi on the Palatine, and was only prevented from treating them in full by the fact that they were awaiting a definitive publication. But the general paucity of earlier material forced her to give short shrift to Republican stucco-work and to consign its origins to the realm of conjecture. She suggested that stucco reliefs first appeared in Italy at the time of Sulla, that they originated in Alexandria, and that they were introduced by way of Campania.

The Bronze Fragments of the Acropolis

It is a misfortune almost necessarily incidental to the excavation of any site so rich in ancient remains as the Acropolis at Athens, that smaller objects and such as have a less obvious archaeological value, are sadly neglected: and the fate of the bronze fragments excavated during the seasons 1885—9 affords the strongest proof of this fact. At the time of the excavation the Greek authorities selected those objects in bronze which had any obvious archaeological interest, and placed these in the larger Museum on the Acropolis. All the other bronze remains were indiscriminately and somewhat carelessly packed in several large boxes and stored in the small Museum. The evil results of this are twofold: in the first place, owing to careless storing and the piling of heavy objects on the top of light, a large number of fragments have been further broken up; and secondly, there is absolutely no record of the place or depth at which any of these were found. How important such a record would have been, will be well realized by any student of Dr. Furtwängler's great work on the Olympia bronzes, though this same also does much to lessen the gravity of our loss.

A New Portion of the Edict of Diocletian from Megalopolis

The inscription which follows came to light during the excavation undertaken this year, at Megalopolis, by the British School at Athens. It stood outside the house of a peasant, Βασίλєιος Πєτράκης, whose father had found it, many years previously, in a field upon the ancient site. The existence of the stone was reported first to the Ephor, Mr. Castroménos, who represented the Greek Government at our excavation. Mr. Castroménos courteously announced it to me, and both of us copied it. At that time we had no idea that it formed part of the ‘Edict of Diocletian’; this was first suggested to me by Mr. Gardner, Director of the School, on my return to Cambridge. Mr. Castroménos' copy is to appear, as I understand, in the ‘Δєλτίον.’ The text and edition which follow are from my own copy and squeeze.The Edict of Diocletian and his colleagues, commonly spoken of either by Mommsen's title ‘De Pretiis Rerum Venalium’ or more briefly as the ‘Edict of Diocletian,’ is known to us already from a large number of fragments, Greek and Latin, found all (with one exception) in different parts of Greece or Asia Minor, and amounting together to many hundred lines. It is still however far from being complete.