Open Core Research Articles

Open Evaluating opportunities and equal: Bolt on the impact change Open University programme culture or core of an equal on

Open Evaluating opportunities and equal: Bolt on the impact change Open University programme culture or core of an equal on

Fine needle aspiration (FNA) of bone tumours: with special emphasis on definitive treatment of primary malignant bone tumours based on FNA

Although clinical and radiological examinations may present clues to the nature of bone lesions, bone tumours require morphological examination of tissue for definitive evaluation. Core needle biopsy and fine needle aspiration (FNA) are gradually becoming more accepted as a substitute for traditional open biopsy. There are several advantages to FNA. The procedure can be used safely in difficult sites such as the vertebrae or pelvis. Hospitalization is unnecessary, and a preliminary diagnosis can be rendered within 15–20 min of aspiration. This reduces patient anxiety and allows rapid triage with coordination of further investigations and discussion of anticipated therapy. Thin needle aspiration is less traumatic than either core needle or open biopsy. Tumour tracking is greatly reduced, limb-sparing surgery is facilitated, wound healing does not delay administration of chemotherapy and there is no significant risk of wound infection. Compared to core needle biopsy, FNA allows rapid preliminary diagnosis as well as aspiration from multiple areas in large tumours enabling an evaluation of tumour heterogeneity. There are also economical benefits; reduced hospitalization and operating room expenses. For most bone tumours, primary and metastatic, it is possible to base the definitive diagnosis on FNA. In addition to strictly defined cytological diagnostic criteria, adjunctive methods such as electron microscopy, immunocytochemistry, DNA-ploidy studies and cytogenetics may all contribute. As is true with open biopsy and core needle biopsy, however, the final assessment is based on combined clinical, radiologic and cytologic findings, necessitating close cooperation between the cytopathologist, orthopaedic surgeon and radiologist.

Open Evaluating opportunities and equal: bolt on the impact change Open University programme culture or core of an equal on

Open Evaluating opportunities and equal: bolt on the impact change Open University programme culture or core of an equal on

98/02444 Low NO x burners for boilers, furnaces, and gas turbines. Drive towards the lower bounds of NO x emissions : Beer, J. M. Combust. Sci. Technol., 1996, 121, (1–6), 169–191

This paper presents the emission characteristics and axial flame temperature distribution of producer gas fired premixed burner. The producer gas fired premixed burner of 150 kW capacity was tested on open core throat less down draft gasifier system in the present study. A stable and uniform flame was observed with this burner. An instrumented test set up was developed to evaluate the performance of the burner. The conventional bluff body having blockage ratio of 0.65 was used for flame stabilization. With respect to maximum flame temperature, minimum pressure drop and minimum emissions, a swirl angle of 60° seems to be optimal. The experimental results also showed that the NOx emissions are inversely proportional to swirl angle and CO emissions are independent of swirl angle. The minimum emission levels of CO and NOx are observed to be 0.167% and 384 ppm respectively at the swirl angle of 45–60°. The experimental results showed that the maximum axial flame temperature distribution was achieved at A/F ratio of 1.0. The adiabatic flame temperature of 1653 °C was calculated theoretically at A/F ratio of 1.0. Experimental results are in tune with theoretical results. It was also concluded that the CO and UHC emissions decreases with increasing A/F ratio while NOx emissions decreases on either side of A/F ratio of 1.0.

Extended defects in wurtzite nitride semiconductors

A synthesis of the latest results on extended defects in wurtzite nitride semiconductors is presented. The principle defect type is that of threading dislocations, the majority of which are edge in character with their lines parallel to the growth direction and Burgers vector a. The other important defects which may influence the device performances are open core screw dislocations which in these materials have been called «nanopipes». Recently, it has been possible to grow unipolar GaN layers by a tight control of the buffer layers, therefore the inversion domain boundaries which cross the active layers can be eliminated. A large number of optical measurements has established that the crystallographic defects (dislocations, stacking faults,...) have an influence on the optical properties of the epitaxial layer. It is noted that better devices will be made in the near future using homoepitaxial GaN layers.

Synthesis, characterization, crystal structures and reactivity of a series of ruthenium nitrene and nitrido carbonyl clusters containing bridging alkyne ligands

The reactions of [Ru3(CO)9(µ3-CO)(µ3-NOMe)] 1 with alkynes, PhC2R, in n-hexane afforded the new cluster [Ru3(CO)9(µ3-NOMe)(µ3-η2-RC2Ph)] (2a, R = H; 2b, R = Ph) in high yields. The molecules consist of an open triangular core of three metal atoms with triply bridging alkyne and µ3-NOMe ligands on opposite sides of the cluster. Upon thermolysis in n-octane, [Ru4(CO)9(µ-CO)2(µ4-NOMe)(µ4-η2-HC2Ph)] 3a, [Ru4(CO)9(µ-CO)2{µ4-NC(O)OMe}(µ4-η2-HC2Ph)] 4a and [Ru5(CO)13(µ-CO)(µ4-NH)(µ4-η2-HC2Ph)] 5a were isolated from 2a, while [Ru4(CO)9(µ-CO)2(µ4-NOMe)(µ4-η2-PhC2Ph)] 3b, [Ru4(CO)9(µ-CO)2{µ4-NC(O)OMe}(µ4-η2-PhC2Ph)] 4b, [Ru4(CO)9(µ-CO)2(µ4-NH)(µ4-η2-PhC2Ph)] 6b and [Ru6(CO)13(µ-H)(µ5-N)(µ3-η2-PhC2Ph)2] 7b were obtained from 2b. The structures of 3a, 3b, 4a and 4b consist of a slightly twisted square base of four metal atoms with quadruply bridging alkyne and µ4-NOMe or µ4-NC(O)OMe ligands on opposite sides of the clusters. Cluster 5a has a structure analogous to that of 3a with quadruply bridging phenylacetylene and µ4-nitrene (NH) ligands but differs from 3a due to the presence of a Ru(CO)4 group on one edge of the tetraruthenium cluster, whilst cluster 7b contains six ruthenium atoms and a µ5-N nitrido atom. Five ruthenium atoms out of the six arrange in a novel wingtip-bridged metal skeleton. The binuclear metallapyrrolidone complex [Ru2(CO)6{µ-η3-HC2(Ph)C(O)N(OMe)}] 8a was isolated from the direct reaction of 1 and phenylacetylene in refluxing n-octane, in which interaction of phenylacetylene with CO and the NOMe nitrene moiety was observed. Complex 3a converts into 4a in refluxing n-octane with or without bubbling CO. Substitution of MeCN with 3a led to the activated [Ru4(CO)8(µ-CO)2(NCMe)(µ4-NOMe)(µ4-η2-HC2Ph)] 9a in moderate yields. Monosubstituted [Ru4(CO)8(µ-CO)2(PPh3)(µ4-NOMe)(µ4-η2-HC2Ph)] 10a was isolated stoichiometrically when 9a was stirred with PPh3. However, direct substitution on 3a with PPh3 in the presence of Me3NO gives disubstituted [Ru4(CO)7(µ-CO)2(PPh3)2(µ4-NOMe)(µ4-η2-HC2Ph)] 11a in addition to 10a. Nucleophilic attack of H– takes place on 3a and 4a and of I– on 3a, a terminal carbonyl ligand is replaced by these anionic ligands and the products were characterized by negative ionization fast atom bombardment mass spectrometry.

Use of fine needle aspiration for solid breast lesions Is accurate and cost-effective

Palpable breast tumors have traditionally been diagnosed with open biopsy or core biopsy. We propose fine needle aspiration biopsy (FNA) as a reliable, cost-saving initial procedure in these patients. Eighty-five palpable solid breast masses of the breast in 85 patients were classified by a combination of physical examination, mammography, and/or ultrasound as probably benign, indeterminate, or highly suspicious for cancer. All tumors had FNA biopsies. All patients had either a confirmatory open biopsy (55) or close clinical follow-up (30) with a mean follow-up of 29 months (range 6 to 36). Thirty-four patients classified as clinically benign had a benign FNA biopsy. No cancers were detected in this group by either open surgical biopsy or clinical follow-up. Twenty patients were classified clinically as indeterminate. All had FNA biopsies, and 6 were either positive for cancer or suspicious for cancer. Fourteen patients had negative FNA biopsies. Five of the 6 abnormal biopsies had cancer on open biopsies. The 1 false-positive result occurred in a lactating patient. Thirty-one patients were classified clinically as highly suspicious for cancer. Twenty-three were confirmed as cancer with FNA biopsy. Eight needed open surgical biopsy to confirm cancer. All 31 patients clinically suspicious for cancer had cancer. In patients classified clinically as highly suspicious or probably benign, FNA was a reliable first diagnostic step (100% positive predictive value, 100% specificity, 87% sensitivity, and 89% negative predictive value). Fine needle aspiration biopsy of solid palpable breast lesions should be the diagnostic procedure of choice for those patients classified clinically as probably benign or clinically as highly suspicious for cancer. Cost analysis revealed elimination of an open biopsy in such cases would save $1,100 per patient. For highly suspicious cases, a negative fine needle aspiration should not deter an open surgical biopsy. For patients classified as indeterminate, fine needle aspiration biopsy results are not reliable enough to determine treatment.

Trade integration in the twentieth century: What does Belgian history tell us?

Trade Integration in the Twentieth Century: What Does Belgian History Tell Us? — This paper studies globalization, protection and the impact of regional trading blocs in the twentieth century. The authors take the perspective of a small open core country in Europe. Using a gravity approach, it can be shown that trade integration in Europe followed a U-shaped pattern during the last hundred years. Moreover, the similarity between the gold standard and the current period is striking. Finally, evidence is found of a strong EC effect, in particular among EC6 countries.

Capture Zone Geometry in a Fractured Carbonate Aquifer

AbstractThis study examined a fractured carbonate aquifer that has a transition from porous media type (continuum) flow near the bedrock surface to discrete fracture (non continuum) flow at depth. Three depth zones were delineated using a borehole flowmeter, borehole video logs, and pumping tests. The upper zone is fractured to the degree where it behaves hydraulically as a continuum, the middle zone is less fractured and behaves as a discretely fractured aquifer, and the lower zone is least fractured, has no measurable fracture interconnection, and behaves as an aquitard. These zones were not related to lithologic boundaries, showing that monitoring well design based solely on lithology may be inappropriate in some fractured systems.The geometries of capture zones in this aquifer were determined by combining the field observations with numerical modeling. The capture zone geometries are very complex, containing thin a really extensive features around fractures in the middle zone which extend over an area 17.5 times greater than the capture area in the upper continuum zone. A capture zone computed with lumped aquifer parameters leads to inaccurate conceptualization of capture zone geometry at this site.The presence of open core hole monitoring wells affected the flow regime under both ambient and pumping conditions. The wells act as short circuits between otherwise isolated fractures and fracture zones. By connecting the continuum to the non continuum flow regime with the wells, ambient flow in the non continuum regime was increased by a factor of 20. Under pumping conditions, the presence of the monitoring wells alters the capture zone of the pumping well. Discrete fractures provide a connection between the pumping and observation wells at depth that causes separate cones of depression to be formed around observation wells in the upper aquifer, and thus, the capture zone in the near‐surface aquifer may include multiple, isolated areas around monitoring wells.

Synthesis of trinuclear mixed-metal clusters Os2Fe(CO)10L2(L = OH, I, CO). The crystal structures of Os2Fe(CO)10(μ-OH)2 and Os2Fe(CO)12 · 0.41Os3(CO)12

The heterometallic clusters Os 2 Fe(CO) 10 ( μ -X) 2 (X = OH, I) were obtained from the binuclear osmium complexes Os 2 (CO) 6 X n (X = Cl, n = 4; X = I, n = 2). The structure of Os 2 Fe(CO) 10 ( μ -OH) 2 was determined by a single-crystal X-ray diffraction analysis. The crystal is triclinic and crystallizes in the space group P l¯ and a = 14.009( 6 ), b = 13.330( 4 ), c = 9.511(2)Å, α = 103.69(2), β = 81.83(3), γ = 102.22(3)°, V = 1699(1) Å 3 , Z = 4, D calc = 2.969g cm −3 , R = 0.093 for 2359 independent reflections ( F o > 6 σ ( F o )). The cluster consists of an open triangular OsFeOs metal core with no Os-Os bond. The bridging OH groups are coordinated semiaxially and span the Os-Os edge. On heating in the presence of an excess of Fe 2 (CO) 9 , the Os 2 Fe(CO) 10 ( μ -I) 2 cluster is converted to Os 2 Fe(CO) 12 . The co-crystallate Os 2 Fe(CO) 12 · 0.41Os 3 (CO) 12 was isolated from the solution of Os 2 Fe(CO) 10 ( μ -I) 2 , as the product of decomposition of the initial cluster. It crystallizes in the monoclinic system, space group P 2 1 / n , with a = 8.056(2), b = 14.743(2), c = 14.520(2)Å, β = 100.62(1)°, V = 1695.0(5)Å 3 , Z = 4, D calc = 3.179g cm −3 and R = 0.0250 for 1997 independent reflections ( F o > 4 σ ( F o )).

An open cycle gas core fusion rocket for space exploration

A nuclear propulsion system that utilizes fusion reactions to heat a plasma in a magnetically confined device is examined as a potential rocket. It makes use of a high density plasma in a magnetic mirror geometry with a collision mean free path much shorter than its length. Under these conditions the plasma behaves like a fluid with confinement properties dictated by gasdynamic laws. Accordingly, the plasma escape from the device is analogous to the flow of a gas into vacuum from a vessel with a hole. Such a system is capable of producing a very high specific impulse albeit at modest thrust. One approach for enhancing the thrust is to use an auxiliary hydrogen propellant that could be regeneratively heated before it is introduced into the reactor chamber. As is flows past the fusion plasma it will be further heated by the radiation (bremsstrahlung and synchrotron) emanating from the plasma, and upon emergence from the nozzle it will generate the desired thrust. The system thus functions much like an open cycle gas core rocket with very attractive propulsive capabilities. In this paper we present the underlying physics principles of such a concept and assess its capability by applying the results to a round trip mission to Mars. It is shown that the propulsion parameters exceed those of a gas core fission reactor and without many of major hydrodynamic problems confronted by the latter.

Study of open-core dislocations in GaN films on (0001) sapphire

This article deals with a plan view and cross section transmission electron microscopy study of columnar defects in GaN films epitaxially grown on sapphire (0001). They are identified as open-core (0001) Burgers vector dislocations. Their behavior along the film thickness is described: it alternates from open core sections (nanopipes) to closed core sections. This alternating behavior is observed in the first 0.5 μm close to the interface with sapphire.

Microstructure of GaN epitaxial films at different stages of the growth process on sapphire (0 0 0 1)

The microstructure of GaN films at different stages of a classical two steps growth process is studied using TEM. The buffer layer grown at low temperature (600°C) exhibits a mixed cubic-hexagonal columnar microstructure. Numerous defects are present to accomodate the misorientations between micrograins. During the following annealing step up to 1050°C, the microstructure drastically changes: cubic islands remain on the top of a film with hexagonal structure. The buffer layer at this stage is still highly polycrystalline. The microstructure of micrometer thick films grown at 1050°C could be separated in two zones. Close to the interface with sapphire, misfit dislocations, basal stacking faults and nanocavities are observed. We propose a mechanism of relaxation of the strain due to the difference of thermal expansion coefficients which could explain the presence of stacking faults. The existence of nanocavities is supposed to be related to a contamination by oxygen. After a thickness of 0.5 μm, two types of threading defects remain: edge dislocations with 1/3〈1 12¯0〉 Burgers vector which accommodate slight misorientations between grains, and nanopipes. These nanopipes are identified as open core dislocations with (0 0 0 1) Burgers vector. They have an alternating behaviour: close core, open core. The microstructure of this bulk zone duplicates the microstructure of the buffer layer at a higher scale, pointing out the crucial importance of the first steps of the growth.

Syntheses and molecular structures of ruthenium carbonyl complexes containing 1,2-naphthoquinone-1-oximate ligands

K. Ka-Hong Lee and W. Wong, J. Chem. Soc., Dalton Trans., 1997, 2987 DOI: 10.1039/A703307I

A new concept of combined transformers

AbstractThe basic characteristics of a new concept of combined transformers consisting of an inverse current transformer and a voltage transformer with open core, are described. The results of the research and testing of impulse and AC voltage distribution, accuracy class, influence of the current transformer on the voltage transformer and vice versa are given. Thanks to its technology and simplicity, the new concept allows the commercial manufacture of combined transformers for the highest equipment voltages up to 420 kV inclusive.

Ab initio calculation of electronic structure, crystal field, and intrinsic magnetic properties of Sm2Fe17, Sm2Fe17N3, Sm2Fe17C3, and Sm2Co17.

In a comparative study we calculated the spin and orbital moments, spin and charge densities, and 4f crystal field (CF) parameters of the rare-earth transition-metal intermetallics ${\mathrm{Sm}}_{2}$${\mathrm{Fe}}_{17}$, ${\mathrm{Sm}}_{2}$${\mathrm{Fe}}_{17}$${\mathit{Z}}_{3}$ (Z=C,N), and ${\mathrm{Sm}}_{2}$${\mathrm{Co}}_{17}$ using a relativistic optimized linear combination of atomic orbitals method. The itinerant valence electron states were treated in the local-spin-density approximation (LSDA), whereas the localized 4f states were described as open core states within the self-interaction-corrected LSDA. The calculations yield magnetic moments in good agreement with experiment. While all local moments of ${\mathrm{Sm}}_{2}$${\mathrm{Fe}}_{17}$ increase upon lattice expansion, the moments of atoms neighboring the interstitial sites decrease and those of more distant Fe atoms increase upon insertion of interstitial N or C. In N interstitial atoms all ${2\mathrm{p}}_{\mathrm{\ensuremath{\alpha}}}$ orbitals are polarized antiparallel to their respective Fe and Sm neighbor atoms in the bond direction, whereas in C all ${2\mathrm{p}}_{\mathrm{\ensuremath{\alpha}}}$ orbitals are polarized antiparallel to the Fe atoms neighboring the interstitial site. The second-order CF parameters ${\mathit{A}}_{2}^{0}$ dominating the rare-earth magnetocrystalline anisotropy are found to have the same sign and order of magnitude as those derived from magnetization data. In accordance with experiment the calculated negative ${\mathit{A}}_{2}^{0}$ is larger for the Co compound than for the Fe parent compound and is strongly increased upon insertion of interstitial N or C. The agreement between theory and experiment is improved by taking into account the CF contribution arising from the asphericity of the exchange-correlation potential of the non-4f states. \textcopyright{} 1996 The American Physical Society.

Synthesis and crystal structure of [(CO) 6Fe 2(μ-SeCH 3) 2

The synthesis and crystal structure of (CO) 6Fe 2(μ-SeMe) 2 (1) is reported. The dianion [Fe 2(CO) 6(μ-SeMe) 2] 2−, obtained by the reaction of Fe 2(CO) 6(η-Se 2) with nBuli, reacted with iodomethane to give 1. Compound 1 has been characterised by IR, 1H and 13C NMR spectroscopy and elemental analysis. Its structure has been elucidated by X-ray crystallography. The compound belongs to the orthorhombic space group PC2 1 n with a = 7.202(1), b = 10.544(1), c = 18.344(3) Å, Z = 4. The structure was solved by direct methods and refined by full-matrix least-squares methods using NRCVAX programs, correcting for extinction, to R = 0.067 and R w = 0.073 for 854 observed reflections. The structure consists of an Fe 2Se 2 open butterfly core with each Fe atom containing three terminal carbonyl groups and each Se atom having a CH 3 group bonded to it at the equatorial sites.

Calculation of crystal-field parameters for rare-earth noble metal alloys

Abstract The crystal-field (CF) parameters for 4f electrons of a series of rare earth impurities in Ag and Au have been evaluated from first-principles density functional calculations of the charge distribution which are based on an optimized LCAO scheme. The localized 4f states are treated as ‘open core shell’. By including the self-interaction correction for the 4f states, artificial constraints on the 4f charge density employed in earlier density functional CF calculations are avoided. The calculated parameters are compared with recent neutron scattering data.

The development of an implantable artificial lung.

This report describes the development of an implantable gas exchange device. The device is composed of hollow fiber elements wound around a central open core enclosed in a compliant outer casing, offering very low resistance to blood while providing adequate gas exchange. The purpose of this study was to determine if this device design can completely support the gas exchange requirements of a large animal when the device is placed in series with the main pulmonary artery (PA). Six 40-80 kg adult sheep were used. The device was placed with vascular grafts anastomosed end to side on the proximal and distal main PA. The study began with the entire right ventricular blood flow being diverted through the device by occlusion of a snare around the PA between the vascular grafts. Total gas exchange then was provided by the device and the endotracheal tube was clamped. Results showed that this pumpless potentially implantable device is capable of completely supporting the gas exchange requirements of the experimental animals for up to 8 hours in the acute setting without significant change in cardiac index (CI) and oxygen consumption (VO2) compared with baseline. CI = 55.0 +/- 17.0 cc/min/kg versus 45.0 +/- 17.3 cc/min/kg. VO2 = 1.90 +/- 0.96 cc O2/min/kg versus 2.08 +/- 0.54 cc O2/min/kg.

Calculated crystal-field parameters for rare-earth impurities in noble metals

From first-principles density-functional calculations of the charge distribution the crystal-field (CF) parameters for 4f states of Er and Dy impurities in Ag and Au have been evaluated. The calculations are based on an optimized linear combination of atomic orbitals scheme, where the local-density approximation (LDA) is used for the conduction-electron states, while the localized rare-earth 4f states are treated as ``open core shell.'' As the 4f localization cannot be properly described within LDA, a self-interaction correction for the 4f states is included. In this way, any artificial constraints on the 4f charge density employed in earlier first-principles CF calculations are avoided. The calculated CF parameters agree well with recent neutron scattering data.