bluuebunny/crossref_metadata_2025 huggingface dataset:
Platelet Membrane Alterations Following Collagen Stimulation
Authors: Webber A. J. , Bennett E. A. , Booth W.
Published: June 2019

Thrombin stimulates the release from platelets of a lipoprotein membrane complex believed to be platelet factor 3 (Webber and Johnson, Am. J. Path., 60, 19, 1970) and microfilaments of dimensions consistent with thrombosthenin (Webber and Budtz-Olsen, Brit. J. Haemat., 26, 275, 1974).

This paper describes an ultrastructural study of stimulation of the lipoprotein membrane complex by collagen. The complex was similar to that produced by thrombin and usually consisted of concentric layers 150-200 Å wide, separated by a similar distance. Cytochalasin B had no effect on the release of the membrane complex.

Within 10 seconds of collagen addition to platelet rich plasma scanning electron microscopy showed the adherence of platelets to collagen fibres, pseudopod formation, and surface protrusions consistent with the release of the membrane complex. At 20 seconds, platelets appear fully aggregated with filaments present on the platelet surface.

These observations are consistent with the view that, upon collagen stimulation, PF3 becomes available on the platelet surface, accelerates the production of thrombin and, in turn, thrombin acts on the platelet to stimulate the release of contractile microfilaments which contribute to platelet aggregation.
Formation and Destruction of Platelet Aggregates in Viscometric Flow
Authors: Rieger H. , Schmid-Schönbein H.
Published: June 2019

Even after pseudopodia formation platelets - unlike all other known formed blood elements - remain dispersed in stasis and creeping flow and become aggregated only in the presence of a minimum amount of shearing. The “rheoaggregometer” (Rieger et al., Pflüger’s Archiv, 343, R 33, 1973) allows to measure the minimum shear rates necessary for platelet aggregation (PA), as well as the initial rate and the maximum extent of PA in citrated PRP.

PA is quantified photometrically as a function of variable shear rates. The initial rate of PA steadily increases with increasing shear rates up to 460 sec-1. However, the maximal extent of PA (indicating the mechanical integrity of formed aggregates) saturates at about 35 sec-1 and then decreases because of a destruction of formed aggregates and of prevention of further PA. The aggregability of the platelets, as reflected by various degrees of shape changes, is enhanced by a drop of temperature and a rise in pH as well as by the so called aggregating agents (e.g. epinephrine 10-6 up to 10-9 M/l) : consecutively lower shear rates (lower effects of collision) are necessary to induce PA. In citrated PRP stable platelet aggregates are produced only within a defined range of shear rates. Platelet aggregability and aggregate stability are independent variables influenced by different experimental conditions.
Binding of Ca++ to Human Prothrombin
Authors: Benarous R. , Elion J.
Published: June 2019

The Ca++ binding properties of human prothrombin were studied by equilibrium dialysis using 45 calcium chloride at +4° C with prothrombin concentration of about 1 mg/ml equilibrated in 0.025 M Tris HCl, 0.12 M NaCl buffer pH 7.4. Scatchard plots obtained were similar to those described by Steenflo (1973) for bovine prothrombin, suggesting a positive cooperativity in the binding of Ca++ with a maximum ratio of bound Ca++/free Ca++ of 3 moles of Ca++ bound per mole of protein.

The total number of binding sites was found to be at about 7, less than 10 to 12 found for bovine prothrombin. Ca++ binding was dependent on pH variation of the buffer with a maximum value for pH 8.5. Chemical modifications of carboxyl groups of prothrombin according to Hoare and Koshland (1967) abolished the Ca++ binding ability of the molecule confirming the essential role of these residues in this specific property of prothrombin.
Isolation and Properties of the Abnormal Factor X Induced by Vitamin K Antagonist (PIVKA-X)
Authors: Lindhout M. J. , Kop-Klaassen B.H.M.
Published: June 2019

The abnormal factor X induced by vitamin K antagonist could be isolated from the plasma obtained from a cow under short term treatment with Marcoumar®. A 3,500 fold purification was achieved at a 10% yield. A single band was seen on polyacrylamide gel electrophoresis. The protein was immunologically identical to normal factor X.

After incubation with an activator of factor X from Russell’s Viper Venom (RVV), PIVKA-X shows esterase and proteolytic activity. Although PIVKA-XRVv has no activity in a one-stage factor Xa assay, it seems that the active site is intact, as it could be titrated with p-nitrophenyl-p-guanidinobenzoate (p-NPGB).

In the absence of phospholipids and Ca++-ions both factor Xa and PIVKA-XRVv activate prothrombin at the same low rate. Identical prothrombin subunits are obtained in both cases.
Receptors for 5-Hydroxytryptamine on Rat Blood Platelets
Authors: Drummond A. H. , Gordon J. L.
Published: June 2019

When 5-hydroxytryptamine (5HT) or its analogue, 5-methoxy-α-methyltryptamine (5MOαMT) are added to rat citrated platelet-rich plasma (PRP), the platelets change in shape but do not aggregate. The response to both of these agents is inhibited by the 5HT antagonist, cinanserin (IC50 = 3 व 10-9 M). Cinanserin is at least 10,000 times less potent against the active uptake of 5HT (IC50 > 5 व 10-5 M). 5MOαMT is not actively transported by the platelet, although some instantaneous binding can be measured which is independent of temperature (4°-37°). 5MOαMT does not inhibit 5HT uptake over the concentration range at which it induces the shape change (10-8-10-5 M). Binding of (3H)-5HT to rat platelets at 4° indicates the presence of three binding sites, one of which is specifically blocked by cinanserin (IC50 = 2.8 × l0-9 M). Close correlation between the inhibitory potency of various drugs against (3H)-5HT binding and 5HT-induced shape change suggests that this site is the 5HT receptor on the platelet which initiates the shape change. Our results indicate that 5HT induces the platelet shape change by combination with a specific cinanserinsensitive 5HT receptor, which is unconnected with the uptake site.
The Role of Platelets and Leukocytes in Endotoxin-Induced Disseminated Intravascular Coagulation (DIC)
Authors: Gurewich V. , Lipinski B.
Published: June 2019

DIC was induced by two appropriately spaced injections of endotoxin. Evidence of fibrin deposition was determined by a previously described radioactive technique, by autoradiography of kidney slices and by the development of renal cortical necrosis. In animals made leukopenic but not thrombocytopenic by nitrogen mustard, fibrin deposition was inhibited. The degree of inhibition appeared proportional to the degree of leukopenia. Another group of rabbits was made thrombocytopenic but not leukopenic by the injection of neuraminidase (Sigma) 48 hours before the first dose of endotoxin. Thrombocytopenia (< 50,000/mm3) failed to inhibit fibrin deposition and the development of renal cortical necrosis. These animals showed the characteristic biphasic white cell response and an increase in plasma anti-heparin activity. Comparable findings were observed in a patient with DIC secondary to gram negative septicemia. In this patient, a substantial drop in WBC count developed (8.500-900/mm3). Platelet factor 4 determined by an immunoassay (Dr. S. Niewiarowski) was normal. It is concluded that granulocytes but not platelets are essential for endotoxin-induced DIC. It is likely that the increase in anti-heparin activity previously described is derived from white cells and not platelets.
Subunit Structure of Human Factor VIII
Authors: Mourik J. A. van , LaBruyère W. T. , Mochtar I. A.
Published: June 2019

Several investigations have shown that factor VIII is a high molecular weight aggregate and that both non-covalent and disulphide bonds contribute to the stabilization of the macromolecular factor VIII aggregate. As shown previously (1) disruption of non-covalent bonds can be accomplished at relatively low ionic strength and neutral pH and results via a series of homologous oligomers (having constant charge/mass ratios) in 2 immunologically non-related subunits. Thus, the generally accepted concept that factor VIII is constructed of identical subunits seems incorrect. For several reasons we assume that the observed fragmentation at low ionic strength is not due to proteolytic breakdown. However, this view is not favoured by the observation that tryptic and plasmic digestion of factor VIII (in aggregated form) results in gel electrophoresis patterns comparable with those obtained of factor VIII after low ionic strength dissociation. Further, evidence will be presented that the assumption that reduction of factor VIII under denaturating conditions results in a single polypeptide chain is also no longer tenable. As far as the reduction of aggregated factor VIII is concerned our observations agree with data from the literature, that is, reduction of factor VIII results in 1 major subunit with an apparent molecular weight of approximately 270.000. However, when factor VIII is first dissociated at low ionic strength followed by reduction, smaller fragments appear in the electrophoresis pattern. Thus, it seems most likely that the apparent single chain subunit is in fact, constructed of smaller non-covalently linked fragments.

(1) J. A. van Mourik et al. Thrombosis Research, 4, 155, 1974.
Relationship between Factor VIII and von Willebrand’s Factor in Plasma and Serum
Authors: Koutts J. , Gude N. , Firkin B.
Published: June 2019

A monospecific precipitating antibody with no factor VIII procoagulant neutralisation activity, but which inhibited normal ristocetin induced platelet aggregation was produced. The antibody was insolubilised on Sepharose beads. On mixing with normal plasma, factor VIII procoagulant activity (VIII C), von Willebrand factor (vWf) and factor VIII antigen (VIII Ag) were removed in equal proportions. The VIII C lost from plasma was detectable on the Sepharose beads. This activity was removed after treatment of these beads with high molarity solution. Subsequent addition of plasma resulted in a high transfer of VIII C from the plasma to the Sepharose beads without accompanying vWf and VIII Ag. Similar experiments, initially mixing with normal serum showed equivalent binding of vWf and VIII Ag. No independent attachment of VIII C to these beads was demonstrated when they were treated with high molarity solutions and normal plasma then added.

It is suggested that VIII C and vWf exist in plasma as separate but attached molecules in a dynamic equilibrium. In serum, vWf has lost its ability to attach VIII C.
The Plasminogen Activator Content of the Arterial Wall in Different Arteries
Authors: Donner L. , Šafránková D.
Published: June 2019

Six hundred and sixty specimens of thoracic, abdominal aortas, cerebral, carotid, vertebral, pulmonary, coronary, kidney and mesenteric arteries from 110 fresh cadavers were examined for their plasminogen activator content by means of the histochemical method of Todd. The plasminogen activator in pulmonary arteries, kidney and splenic arteries obtained during surgery was estimated. Differences between the fibrinolytic activities, generally found in the adventitia, are given.

Intact arterial endothelium, in contrast to the venous endothelium, is only slightly or not at all active. Endothelium of thoracic aortas detached by scraping and repeatedly washed was tested on fibrin plates with streptokinase. Under these conditions arterial endothelium showed fibrinolytic activity suggesting that endothelium contains proactivator. The fibrinolytic activity of arteries adventitia with atheromatous plaques examined by the histochemical method was higher than in normal arteries.
Purification of Tissue Activator Using Affinity Adsorption on Fibrin and Hydrophobic Interaction Chromatography. Effect of Fibrin on the Enzymatic Properties of the Activator
Authors: Wallén P. , Wiman B.
Published: June 2019

A method for purification of pig heart tissue activator is described. The method is based on affinity adsorption on fibrin and on hydrophobic interaction chromatography. Acetone dry powder from pig heart tissue was extracted with potassium acetate buffer and fractionated with ammonium sulfate essentially as described by Bachmann et al. (Biochemistry 3, 1578, 1964). A fraction obtained between 14 and 66% saturation with ammonium sulfate was dissolved in phosphate buffer pH 7.0 and adsorbed with fibrin prepared from fibrinogen and thrombin free from plasminogen (about 0.7 g fibrin was used for a preparation prepared from 1 kg heart tissue). The fibrin was collected after adsorption for 2 hours and eluted with 2 M KSCN at pH 7. Practically all activity was precipitated by isoelectric precipitation at pH 4.2. Finally the activator was subjected to hydrophobic interaction chromatography on phenylethyl-Sepharose. The activity was eluted with a KSCN-gradient. The specific activity of the active fraction was about 23,000 Ploug units/mg. The over all yield was about 25%. One strong and three weak fractions were obtained on SDS-polyacrylamide gel electrophoresis. In pure systems tissue activator activates plasminogen at a very low rate. In presence of fibrin the rate of activation increases markedly. Even fibrinogen effects the activation but to a much smaller extent.
Evaluation of Five Methods for the Determination of Heparin
Authors: Teien A. , Lie M.
Published: June 2019

Heparin was added in vitro to plasma and the heparin content assayed by five clotting methods. The accuracy was lower in pathological than in normal plasma. At a heparin concentration of 0.5 U/ml plasma the coefficient of variation in eleven pathological plasmas was: Polybrene titration 3 per cent, method of Denson and Bonnar 15 per cent, method of Yin et al. 20 per cent, calcium thrombin time 40 per cent. With the APTT method the results ranged from 0.05 U/ml to above 0.6 U/ml (no clotting in five pathological plasmas).

At a heparin concentration of 0.05 U/ml plasma, only the calcium thrombin time and the factor Xa methods were sensitive, but the coefficient of variation ranged from 61 to 78 per cent. The influence of the concentration of fibrinogen, antithrombin III and α1-acid glucoprotein was studied. It is concluded that of the methods tested, only polybrene titration gives accurate results in pathological plasmas. This method is, however, laborious and insensitive to heparin concentrations below 0.1 U/ml.
Experimental Arterial Thrombosis
Authors: Bourgain R. H.
Published: June 2019

A method for inducing white platelet thrombi in a mesenteric artery of the rat has been standardized. After application of a platinum electrode to the vessel wall a DC current of 200 μA is passed for 60 seconds while the polarity is inversed every five seconds.

After passage of the current topical application of ADP or ATP for three minutes results in the formation of white platelet thrombi.

Mieroprojection of the arterial segment performed on a series of LDR’s (Light Depending Resistances) allows registration of potential variations due to white thrombus formation.

The magnitude of these potentials is linearly related to the thrombus mass.

Computerization of these data is possible after A-D conversion of the signals and appropriate programmation.
Inhibition of Fibrinolysis in Burn Wound Infection
Authors: Andes W. A. , Lindberg E. B. , McEuen D. D. , Baron J. P.
Published: June 2019

Infection is the leading cause of death following thermal injury. Various indices of fibrinolysis have been found to be disturbed in such patients. This study reports findings in a lethal Pseudomonas aeruginosa burn wound infection in rats, uninfected but burned controls, and preliminary studies in their human counterparts. Sequential studies revealed that as the infected animals neared their demise their plasminogen levels (casemolytic) fell (p < 0.01), serum antiplasmin (method of von Kaulla) but not antiactivator activity rose (p < 0.01), euglobulin lysis times were very prolonged, fibrin-related antigen titers (staphylococcal clumping) were lower and fibrinogen concentrations were slightly higher than in the uninfected-burned controls. Alpha2-acute phase globulins but not α1-macro-globulins (by. K. Ganrot) were 18 times higher in the infected than in uninfected rats. The bacteria did not induce antiplasmin activity when cultured in serum. 3,5-di-todo-salicylic acid Na abolished the antiplasmin activity. Burned patients had no unusual antiplasmin activity on the day of burning but developed high levels coincident with lowered plasminogens.
Subfractions of Fibrinogen Isolated from Human Plasma by Affinity Chromatography
Authors: Hörmann H. , Stemberger A. , Jilg W.
Published: June 2019

Fibrinogen was isolated from human plasma by affinity chromatography using thrombin activated immobilized fibrinogen. Elution with 1.0 M KBr yielded a preparation of 90–95% clottability. It contained, in addition to fibrinogen, polymers and proteins of lower molecular weight. Most of the associated proteins were removed by adsorption of fibrinogen on DEAE-Cellulose followed by stepwise elution. Under these conditions fibrinogen was also separated into several fractions including high solubility fibrinogen, high molecular weight derivatives and a fibrinogen fraction which was associated with another protein. High solubility fibrinogen was investigated in more detail. Its plasmic digestion showed a lag phase which was not recognized, if normal fibrinogen was degraded. This indicates a relatively stable conformation of high solubility fibrinogen.

(Supported by Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 51.)
Prophylaxis of Thromboembolism by Depotheparin in Orthopedic Patients
Authors: Hey D. , Schöndorj T. H.
Published: June 2019

198 patients (mean 59 yrs.) with major hip joint operations were randomized in two groups. Two schedules of depotheparin were administered for thromboembolic prophylaxis: a low dose of heparin (LDH) 3 × 500 LE/10 kg. b.w. started the preoperative day, and a high dose of heparin (HHD) 3 × 1 250 IE/10 kg b.w. beginning the evening of the first postoperative day. 27 control patients received no anticoagulants unless thrombosis occured.

Undue wound bleeding was observed in 10% in all three groups. The mean values of blood (ml) from the drains as well as the postoperative hemoglobin decrease did not show significant differences between the three groups. Wound healing was not retarded in any of the heparin groups, all patients had in the mean the same duration of hospitalization. Significant alterations of clotting factor XIII were not found.

The lowest incident of pulmonary embolism and of phlebothrombosis diagnosed by the Doppler ultrasound technic was in the HDH-group. Similar results reflected the 125-lod-Fibrinogen test which was conducted additionally in 40 patients; deep vein thrombosis of the lower limbs was also significantly reduced in the HDH-group. The prophylaxis by LDH proved to be better than in the untreated controls but was not as effective as the HDH.

The immunological determinations of antithrombin III were of no diagnostic value.
Activation and Consumption of Factor VII as Reflected by Thrombotest During Fibrinolytic Therapy with Streptokinase
Authors: Arnesen H. , Venneröd A. M. , Laake K. , Godal H. C.
Published: June 2019

Thrombotest is sensitive to the procoagulant effect of plasmin in vitro (Godal & Theodor 1965), and an initial transient increase in Thrombotest values has been observed in patients on treatment with streptokinase (Blix & Arnesen 1969) and urokinase (Godal & Arnesen 1971). Recently, plasmin has been shown to activate and later destroy factor VII in a purified system (Laake & Österud 1974).

In the present study, Thrombotest and coagulation factor analyses were performed during the initial phase of therapy with streptokinase. A marked initial increase in Thrombotest values was found. Simultaneously, a corresponding activation of factor VII was obtained, whereas the factors II, IX and X remained unchanged. Subsequently, a fall in the factor VII activity and a corresponding fall in Thrombotest values were observed.

It is concluded that activation and consumption of factor VII are responsible for the changes in Thrombotest values observed during fibrinolytic therapy.
Epidemiology of Thrombosis in Nigerians. Study of Platelet and Fibrinolytic Parameters
Authors: Dupuy E. , Flemming A.F. , Caen J. P.
Published: June 2019

The infrequency of atherosclerosis and arterial disease and the relative thrombocytopenia reported in Nigerians led us to investigate platelet number and function and fibrinolytic activity in Nigerian non-elite (blood donors) Nigerian elite (hospital senior staff) and Europeans living in Zaria.

The relative thrombocytopenia in Nigerians was confirmed, and counts were between 100–180 × 109/1 in 26 out of 35 subjects. Platelet aggregation using adrenaline and collagen were in the same range in all groups. An early disaggregation with ADP was found in one third of all Nigerians. Platelet aggregation with ristocetin in the Nigerian elite was less than 50 per cent of European values in 10/16 subjects; platelets of 12/17 non-elite subjects did not aggregate at all.

The bleeding time (Ivy) and factor VIII coagulant activity did not differ in the three groups. Fibrinolytic activity was higher in Nigerians than Europeans.

Many factors could be involved in these differences, including splenomegaly, parasitic infections, increases in immunoglobulins, greater physical activity and the healthier endothelium in Nigerians.
A Rare Case of Bilateral Vertebral Artery Dissection Associated with Essential Thrombocythemia
Authors: Raza Hafiz Khuram , Jing Jia , Chen Hao , Zhu Jienan , Zhang Zuohui , Chansysouphanthong Thitsavanh , Cui Guiyun , Hua Fang , Ye Xinchun , Shi Hongjuan , Jiang Haiyang
Published: June 2019

A young patient presented to our hospital with ischemic stroke. She underwent a routine blood test, head computed tomography (CT), brain magnetic resonance imaging, a bone marrow biopsy, and CT angiography. Her diagnosis was a bilateral vertebral artery dissection associated with essential thrombocythemia (ET). She was treated with antiplatelet therapy and a stent implantation. The association of bilateral vertebral artery dissection with ET is rare. An early diagnosis and timely management is key to the best outcome.
Photoelastic Analysis of Two Different Cementless Femoral Stems for Total Hip Arthroplasty in a Canine Model
Authors: Kawamoto Fernando Y. K. , Minto Bruno W. , Diogo Lucia M. I. , de Faria Luis G. , Shimano Antonio C. , Macedo Ana P. , Camassa José A. A. , Dias Luis G. G. G.
Published: June 2019

Objectives The aim of this article was to analyse and compare internal stress generated at different points of a femoral photoelastic model after insertion and axial load application using two different cementless femoral stems for total hip arthroplasty in dogs: a collared stem combined with limited textured surface and absence of grooves and a collarless stem with fully textured surface and grooves.

Methods Ten femoral photoelastic models, divided into two groups, were created using two different designs of cementless femoral stems. The models were submitted to axial loading on the femoral head in a universal test machine. The internal stress (kPa) around the femoral stems was evaluated at seven predetermined points using a transmission polariscope.

Results The internal stress at the femoral calcar was larger in the models with collared stem combined with limited textured surface and absence of grooves (p < 0.05). No differences were identified between the groups in the other points (p > 0.05), corresponding to the tip of the stems and proximal lateral region of the femur.

Conclusions The collar of femoral stem combined with the absence of grooves and more limited textured surface increase the axial load transmission to the femoral calcar, and in vivo, it may act to reduce complications, such as subsidence and stress shielding. However, other biomechanical tests and clinical evaluations must be performed to determine other important aspects for the implantation of these prostheses.
Outcome of Nonketotic Hyperglycinemia in Lebanon: 14-Year Retrospective Review
Authors: Shbarou Rolla M. , Boustany Rose Mary , Daher Rose T. , Pakdel Parisa , Noureddine Abir , Karam Pascale E.
Published: June 2019

Nonketotic hyperglycinemia is a rare inborn error of glycine metabolism characterized by a severe metabolic encephalopathy with drug-resistant seizures. Here, we report the outcome of nonketotic hyperglycinemia in a cohort of patients diagnosed and followed-up at a tertiary care reference center in Lebanon, between 2000 and 2014.

Eight out of 12 patients with nonketotic hyperglycinemia were retrospectively reviewed. The remainders were excluded for incomplete data. The majority of cases presented with seizures and hypsarrhythmia or burst suppression patterns. Half of the patients died. Survival varied between 7 days and 18 years. Seizures remained unresponsive with poor outcome, despite standard supportive care and antiepileptic therapy; however, two patients were responsive to ketogenic diet and one of them became seizure-free.

Scarce data on the outcome of nonketotic hyperglycinemia patients from the Middle East and North Africa region are available. The ketogenic diet, in combination with standard therapies, appears to be effective in controlling the seizures in this devastating disorder. Larger multicenter studies are still needed to establish the role of the ketogenic diet in nonketotic hyperglycinemia.
Investigation of defects influencing performance of type-II InAs/GaInSb superlattice based infrared PIN type photodetectors
Authors: Maximenko Sergey I. , Bassim Nabil D. , Aifer Edward H. , Jackson Eric M. , Nolde Jill A. , Affouda Chaffra A. , Canedy Chadwick L. , Vurgaftman Igor , Meyer Jerry R.
Published: June 2019

We report on an investigation of dark current contributions from common microscale crystallographic defects in type-II InAs/GaInSb superlattice infrared PIN type photodiode structures grown on (100) GaSb substrates and have identified three general classifications. Defects on several wafers of varying design were examined from multiple perspectives to correlate electrical activity with structural properties, to develop the identification and classification scheme. Active defects were first identified by current density vs voltage (J-V) measurements and electron beam induced current (EBIC) scans of individual diodes with micrometer resolution. The EBIC scans were then correlated with plan-view optical and atomic force microscopy images, both before and after anisotropic etch-pit analysis using a newly developed etchant. The atomic scale structure of active and inactive defects was then compared using cross-sectional transmission electron microscopy (TEM) on vertical slices of defects extracted using focused ion beam milling. Analysis of the TEM images yielded important clues as to the structure and root causes of benign and active defects, in which only significant disruptions at the epi-substrate interface appear to play a key role in producing microscale defects that efficiently promote dark current.
Tunable microfluidic standing air bubbles and its application in acoustic microstreaming
Authors: Liu Jixiao , Li Bowen , Zhu Tong , Zhou Yidi , Li Shanshan , Guo Shijie , Li Tiejun
Published: June 2019

Microbubbles are often used in chemistry, biophysics, and medicine. Properly controlled microbubbles have been proved beneficial for various applications by previous scientific endeavors. However, there is still a plenty of room for further development of efficient microbubble handling methods. Here, this paper introduces a tunable, stable, and robust microbubble interface handling mechanism, named as microfluidic standing air bubbles (μSABs), by studying the multiphysical phenomena behind the gas–liquid interface formation and variation. A basic μSAB system consists specially structured fluidic channels, pneumatic channels, and selectively permeable porous barriers between them. The μSABs originate inside the crevice structures on the fluidic channel walls in a repeatable and robust manner. The volumetric variation of the μSAB is a multiphysical phenomenon that dominated by the air diffusion between the pneumatic channel and the bubble. Theoretical analysis and experimental data illustrate the coupling processes of the repeatable and linear μSAB volumetric variation when operated under common handling conditions (control pneumatic pressure: −90 kPa to 200 kPa). Furthermore, an adjustable acoustic microstreaming is demonstrated as an application using the alterable μSAB gas–liquid interface. Derived equations and microscopic observations elucidate the mechanism of the continuous and linear regulation of the acoustic microstreaming using varying μSAB gas–liquid interfaces. The μSAB system provides a new tool to handle the flexible and controllable gas–liquid interfaces in a repeatable and robust manner, which makes it a promising candidate for innovative biochemical, biophysical, and medical applications.
Application of the statistical moment method to melting properties of ternary alloys with FCC structure
Authors: Cuong Tran Dinh , Hoc Nguyen Quang , Phan Anh D.
Published: June 2019

The high-pressure melting properties of the ternary alloy AlCuSi with face-centred cubic structure are theoretically investigated using the statistical moment method. We calculate the melting temperature for the alloy under pressure up to 80 GPa. The dependence of the melting temperature on the content of alloying elements is also studied. Our results agree well with previous experiments, simulations, and other theoretical calculations.
Non-Schmid effect of pressure on plastic deformation in molecular crystal HMX
Authors: Pal Anirban , Picu Catalin R.
Published: June 2019

The energetic molecular crystal cyclotrimethylene trinitramine (HMX) is a key constituent in common plastic bonded explosives. Its plastic deformation under shock conditions is important in reaction initiation and detonation. Here, we study the effect of high pressure on dislocation slip using isothermal-isobaric atomistic simulations. We consider two slip planes, (011) and (101), that are reported to be most active under ambient conditions. For all slip systems considered, the effect of pressure is to increase the critical resolved shear stress for dislocation slip. Pressure may fully inhibit dislocation-based plasticity if the resolved shear stress is not increased in proportion. On the other hand, at sufficiently high shear stresses, the crystal loses shear stability. Therefore, in a broad range of shock conditions, plastic deformation takes place by a combination of dislocation glide in some slip systems and localization in some other systems, with dislocation activity being gradually inhibited as the shock pressure increases. This provides new data on the physical basis of plastic deformation in HMX, indicating that mesoscale representations of plasticity must include shear localization, which is more important under these conditions than dislocation plasticity.
3D nanoprinting via focused electron beams
Authors: Winkler R. , Fowlkes J. D. , Rack P. D. , Plank H.
Published: June 2019

Additive manufacturing of three-dimensional objects on the nanoscale is a very relevant topic but still a highly challenging task. Among the pool of nanofabrication techniques, focused electron beam induced deposition (FEBID) has recently developed from a trial-and-error laboratory method to a predictable 3D nanoprinting technology with unique advantages. This perspective article first introduces the basic principles of 3D-FEBID, followed by an overview of historical developments with a particular emphasis on the last three years. Here, we examine different aspects of 3D nanoprinting such as the instrumental setup, fundamental growth mechanisms, simulations, computer aided design software solutions, material properties, and application studies. For each aspect, the individual challenges and limitations are discussed. In addition, we share our outlook about possible solutions and studies currently under investigation. As a perspective, we also address the most urgent milestones of the future and speculate on applications ranging from optics to mechanics, magnetics, and electronics, all of them benefiting from the recently improved 3D FEBID synthesis technique.
The effects of electron surface interactions in geometrically symmetric capacitive RF plasmas in the presence of different electrode surface materials
Authors: Sun Jing-Yu , Wen De-Qi , Zhang Quan-Zhi , Liu Yong-Xin , Wang You-Nian
Published: June 2019

Particle-in-cell/Monte Carlo collision (PIC/MCC) simulations are performed to investigate the asymmetric secondary electron emission (SEE) effects when electrons strike two different material electrodes in low pressure capacitively coupled plasmas (CCPs). To describe the electron-surface interactions, a realistic model, considering the primary electron impact energy and angle, as well as the corresponding surface property-dependent secondary electron yields, is employed in PIC/MCC simulations. In this model, three kinds of electrons emitted from the surface are considered: (i) elastically reflected electrons, (ii) inelastically backscattered electrons, and (iii) electron induced secondary electrons (SEs, i.e., δ-electrons). Here, we examined the effects of electron-surface interactions on the ionization dynamics and plasma characteristics of an argon discharge. The discharge is driven by a voltage source of 13.56 MHz with amplitudes in the range of 200–2000 V. The grounded electrode material is copper (Cu) for all cases, while the powered electrode material is either Cu or silicon dioxide (SiO2). The simulations reveal that the electron impact-induced SEE is an essential process at low pressures, especially at high voltages. Different electrode materials result in an asymmetric response of SEE. Depending on the instantaneous local sheath potential and the phase of the SEE, these SEs either are reflected by the opposite sheath or strike the electrode surface, where they can induce δ-electrons upon their residual energies. It is shown that highly energetic δ-electrons contribute significantly to the ionization rate and a self-bias forms when the powered electrode material is assumed to be made of SiO2. Complex dynamics is observed due to the multiple electron-surface interaction processes and asymmetric yields of SEs in CCPs.
Liquid-liquid separation of aqueous solutions: A molecular dynamics study
Authors: Yagasaki Takuma , Matsumoto Masakazu , Tanaka Hideki
Published: June 2019

In the liquid-liquid phase transition scenario, supercooled water separates into the high density liquid (HDL) and low density liquid (LDL) phases at temperatures lower than the second critical point. We investigate the effects of hydrophilic and hydrophobic solutes on the liquid-liquid phase transition using molecular dynamics simulations. It is found that a supercooled aqueous NaCl solution separates into solute-rich HDL and solute-poor LDL parts at low pressures. By contrast, a supercooled aqueous Ne solution separates into solute-rich LDL and solute-poor HDL parts at high pressures. Both the solutes increase the high temperature limit of the liquid-liquid separation. The degree of separation is quantified using the local density of solute particles to determine the liquid-liquid coexistence region in the pressure-temperature phase diagram. The effects of NaCl and Ne on the phase diagram of supercooled water are explained in terms of preferential solvation of ions in HDL and that of small hydrophobic particles in LDL, respectively.
Orientation-dependent indentation response of helium-implanted tungsten
Authors: Das Suchandrima , Yu Hongbing , Tarleton Edmund , Hofmann Felix
Published: June 2019

A literature review of studies investigating the topography of nano-indents in ion-implanted materials reveals seemingly inconsistent observations, with reports of both pile-up and sink-in. This may be due to the crystallographic orientation of the measured sample point, which is often not considered when evaluating implantation-induced changes in the deformation response. Here, we explore the orientation dependence of spherical nano-indentation in pure and helium-implanted tungsten, considering grains with ⟨001⟩, ⟨110⟩, and ⟨111⟩ out-of-plane orientations. Atomic force microscopy of indents in unimplanted tungsten shows little orientation dependence. However, in the implanted material, a much larger, more localized pile-up is observed for ⟨001⟩ grains than for ⟨110⟩ and ⟨111⟩ orientations. Based on the observations for ⟨001⟩ grains, we hypothesize that a large initial hardening due to helium-induced defects is followed by localized defect removal and subsequent strain softening. A crystal plasticity finite element model of the indentation process, formulated based on this hypothesis, accurately reproduces the experimentally observed orientation-dependence of the indent morphology. The results suggest that the mechanism governing the interaction of helium-induced defects with glide dislocations is orientation independent. Rather, differences in the pile-up morphology are due to the relative orientations of the crystal slip systems, sample surface, and spherical indenter. This highlights the importance of accounting for crystallographic orientation when probing the deformation behavior of ion-implanted materials using nano-indentation.
Fourier single-pixel imaging using fewer illumination patterns
Authors: Deng Huaxia , Gao Xicheng , Ma Mengchao , Yao Pengcheng , Guan Qingtian , Zhong Xiang , Zhang Jin
Published: June 2019

Single-pixel imaging (SPI), which is generally based on computational imaging, has the advantages of a wide bandwidth and the ability to image objects beyond the visual field. However, the major challenge in developing SPI is the large number of illumination patterns that are required. Unlike traditional SPI that relies on random measurement patterns, the SPI method proposed in this letter involves a two-step phase shift that reduces greatly the required number of illumination patterns. Theoretical analysis shows that 6724 illumination patterns are required to reconstruct a 128 × 128-pixel image whose peak signal-to-noise ratio exceeds 30, and these can be projected in 0.3362 s with a digital micromirror device working at full speed. Compared to SPI with a four-step phase shift, half the number of illumination patterns are required. Verification experiments show that the reconstructed images can be obtained even at a sampling ratio of 20%. The proposed SPI with a two-step phase shift is an effective means of requiring fewer illumination patterns and has great potential in dynamic detection.
Velocity dependent potential effects on two-electron quantum dot in plasmas
Authors: Bahar M. K. , Soylu A.
Published: June 2019

In this study, for the first time, the effects of the velocity-dependent potential (VDP) on the energies of a two-electron parabolic quantum dot (TEPQD) in Debye and quantum plasma environments depicted by a more general exponential cosine screened Coulomb (MGECSC) potential are taken into consideration. The Schrödinger equation is modified by combining the MGECSC potential and VDP, solving numerically via the asymptotic iteration method. The Schrödinger equation with VDP is basically another type of one with position-dependent mass. The effects of VDP on two interacting electrons inside the parabolic quantum dot in plasmas are probed by considering the isotropic form factor with the harmonic (ρ(r)=ρ0r2) and constant (ρ(r)=ρ0) form. The alternativeness of the plasma shielding parameters to each other, the confinement parameter of the quantum dot, and the VDP parameters on energies and possible radiations of TEPQD are also discussed.
Transport properties of zwitterion glycine, diglycine, and triglycine in water
Authors: Khanal Shyam P. , Kandel Yadav Prasad , Adhikari Narayan P.
Published: June 2019

Diffusion, transport of mass in response to concentration and thermal energy gradient, is an important transport property, vital in material science and life science. In the present work, we have studied about the diffusion of zwitterion glycine, zwitterion diglycine and zwitterion triglycine in SPC/E model of water using classical molecular dynamics. Self and binary diffusion coefficients of aqueous solution of these molecules have been estimated using Einstein’s method. Our results agree with experimental data reported in literatures. Temperature dependency of diffusion of glycine in water has been explored using estimated values of self and binary diffusion coefficients at four different temperature. Effects of peptide bond formation in diffusion has been studied using peptide chain composed of up to three monomers of glycine. The system-size dependence of diffusion coefficient has been studied and the shear viscosity of solvent and system has been calculated. Also, the diffusion coefficient of zwitterion glycine in other water model TIP4P/2005 has been estimated. The structure of the system has been analyzed using radial distribution function of different atoms.
Protamine composition of koala and wombat spermatozoa provides new insights into DNA stability following cryopreservation
Authors: Johnston S. D. , López-Fernández C. , Arroyo F. , Roy R. , Holt W. V. , Gosálvez J.
Published: June 2019

To investigate differences in the post-thaw DNA stability of koala and wombat spermatozoa, protamine amino acid sequences were compared and it was found that there were three more arginine residues for the wombat. Koala and wombat spermatozoa, cryopreserved using identical protocols, were examined for changes in sperm DNA fragmentation (SDF) dynamics over 24h of post-thaw incubation. Following validation of a wombat sperm chromatin dispersion test, wombat DNA showed a rate of SDF that was 6-fold higher than for koala spermatozoa (P=0.038). Finally, we examined whether expected differences in chromatin compactness, associated with protamine sequence, had an effect on restriction site accessibility of sperm DNA. Thawed spermatozoa were exposed to Alu I and EcoR1 endonuclease restriction enzymes and the SDF dynamics were observed. Koala spermatozoa exposed to Alu I showed a greater rate of SDF (P=0.01), whereas wombat spermatozoa exposed to EcoR1 showed a greater rate of SDF (P=0.032). We conclude that restriction sites in these species are differentially present or exposed and potentially account for differences in SDF dynamics. Although differences in the arginine composition of protamine may explain relative differences in SDF following cryopreservation, they do not support the hypothesis that increased arginine composition increases DNA stability; rather, increased arginine composition in the wombat may reduce post-thaw chromatin swelling.
Crossover from interaction to driven regimes in quantum vortex reconnections
Authors: Galantucci Luca , Baggaley Andrew W. , Parker Nick G. , Barenghi Carlo F.
Published: June 2019

Significance

Vortex reconnections are fundamental events in fluid motion, randomizing the velocity field, changing the topology, and redistributing energy across length scales. In superfluid helium and atomic Bose–Einstein condensates, vortices are effectively one-dimensional lines called quantum vortices (akin to minitornadoes of a fixed strength). Individual reconnections happen when two vortices collide and subsequently recoil, exchanging heads and tails. Recent experimental progress opens the possibility of answering the important question as to whether reconnections obey a universal behavior. Here we show that the intervortex distance between reconnecting vortices obeys two fundamental scaling laws, which we identify in experimental data and numerical simulations, across homogeneous superfluids and trapped condensates.
Orthographic and phonetic transcriptions of Rhapsodie recording
Authors: Dister Anne , Goldman Jean-Philippe , Marlet Renaud
Published: June 2019

In this chapter, we present the principles that we used for the orthographic and phonological transcriptions in Rhapsodie, as well as the process of automatic segmentation. We opted for three main principles in the orthographic transcription: (1) no adaptation of the standard spelling using tricks such as i-z-ont or pasque; (2) no punctuation; (3) phenomena that are peculiar to speech are duly represented: filled pauses, word repetitions, self-repairs, word fragments, interjections, onomatopoeias, and discourse markers. Then a phonetic transcription is obtained using an automatic grapheme-to-phoneme (g2p) conversion tool followed by manual verification; lastly, on the basis of the sound recording and the phonetic transcription, we provide a multi-layer alignment (or segmentation) at the phonetic, syllabic, and lexical levels, thanks to an automatic approach based on a speech recognition engine.
Annotation tools for syntax
Authors: Gerdes Kim , Kahane Sylvain , Bawden Rachel , Belião Julie , de la Clergerie Eric , Wang Ilaine
Published: June 2019

This chapter is devoted to the presentation of the tools and methods used for the different steps of the semi-automatic syntactic annotation: automatic preprocessing; microsyntactic parsing with the FRMG tool, correction of the parsing with the Arborator tool, agreement analysis, post-validation correction, and development of the final format of the Rhapsodie syntactic treebank. As FRMG is a parser for written French that was not configured to analyze disfluencies and reformulation, we used our manual pile marking to unfold the piles and produce a series of simplified “sentences” with only government relations. Despite having two annotators plus a validator for the corrections, we found a substantial number of errors in the post-validation procedure by using a set of rules to determine the well-formedness of the trees.
Syntax and prosody mapping: What and how?
Authors: Kahane Sylvain , Lacheret-Dujour Anne
Published: June 2019

This chapter is devoted to the intonosyntactic interface, by exploring relationships between major prosodic and macrosyntactic units. It presents different kinds of mapping between intonational periods and illocutionary units, and discusses three basic constructions: alignment, when prosodic and macrosyntactic boundaries coincide; inclusion, when an intonational period groups several illocutionary units; and fragmentation, when an illocutionary unit is segmented by several intonational periods. We also exhibit a singular case of matching, called desynchronization, when neither prosodic boundaries nor macrosyntactic boundaries coincide with each other. These different patterns are discussed in the light of functional and discourse constraints.
CD81 as target for B cell lymphomas
Authors: Küppers Ralf
Published: June 2019

In this issue of JEM, Vences-Catalán et al. (https://doi.org/10.1084/jem.20190186) demonstrate that a particular anti-CD81 antibody shows promising features as a novel immunotherapeutic tool to treat B cell lymphomas. Surprisingly, although CD81 is widely expressed, only minor side effects on other CD81+ immune cells analyzed were observed.
Sensitivity analysis of thorax imaging using two-dimensional Electrical Impedance Tomography (EIT)
Authors: Andiani L , Rubiyanto A , Endarko
Published: June 2019

Electrical Impedance Tomography (EIT) is a non-invasive medical imaging technique which estimates the electrical impedance distribution within some tissue. The study aimed to assess the performance of the EIT system in a thorax imaging by analysis of sensitivity distribution. Sensitivity distribution was visualized using COMSOL Multiphysics simulation in a human thorax represented as an elliptic cylinder phantom consisting of homogeneous and inhomogeneous medium with varying different dimensions of 16 electrode EIT system. Current density distribution was collected for sensitivity analysis using the neighboring method. The sensitivity distribution at each position in the phantom is different. It is caused by the interaction of current density from transmitter and receiver terminal. The different varying parameter of the system can also influence sensitivity distribution. The sensitivity of inhomogeneous phantom is very non-uniformly distributed. The performance of systems was assessed by analysis of the change of sensitivity with the change of electrode dimensions in the homogeneous and inhomogeneous medium.