bluuebunny/crossref_metadata_2025 huggingface dataset:
Partial Neutralization of a Lupus Anticoagulant by Human Immunoglobulin
Authors: Carreras L O , Pérez G N , Martinuzzo M E , Malan-Borel I , Malbrän A , Said P B
Published: July 2018

In a patient with a Lupus Anticoagulant (LA) and recurrent fetal loss, we observed a significant shortening of the APTT after high-dose intravenous immunoglobulin infusion (IVIg).

The LA activity present in patient’s serum and purified IgG was partially neutralized by IVIg in a dose-dependent way. In addition, IgG purified from IVIg and its F(ab′)2 fragment neutralized LA activity of the patient’s IgG. In both cases, the neutralization was dose-dependent and it was obtained with similar molar ratios

The “in vitro” neutralization of LA activity and the immediate shortening of the APTT after IVIg infusion, might be mediated through idiotypel antiidiotype interactions.

On the other hand, the long-lasting effect of IVIg in this patient indicates that it may induce specific inhibition of autoantibody synthesis.

We believe that IVIg should be considered as a therapeutic alternative for LA-related clinical disorders.
Trifluoperazine Enhances Accumulation and Inhibits Phosphohydrolysis of Phosphatidate in Thrombin-Stimulated Platelets
Authors: Holmsen Holm , Dangelmaier Carol A
Published: July 2018

Trifluoperazine (TFP) in concentrations up to 10-15 μM increased the formation of phosphatidic acid (PA) in platelets treated with 0.5 U/ml of thrombin, while higher concentrations of TFP inhibited formation of PA. Liberation of arachidonate (AA) from platelet phospholipids was progressively inhibited as the concentration of TFP increased. At thrombin doses lower than 0.1 U/ml TFP, (≤25 μM) enhanced PA formation with either no effect on AA liberation (6 donors) or with much greater enhancement of PA formation than the decrease in liberation of AA (3 donors). The enhancement of PA formation by TFP did therefore not seem to be due to inhibition of phospholipase A2 (PLA2) by the phenothiazine, which has been suggested. We show further that TFP inhibits PA phosphohydrolase in platelet lysates, although with complex kinetics. It is therefore concluded that the enhancement of thrombin-induced PA production by TFP is not caused by inhibition of PLA2 but could be due to TFP-induced inhibition of PA phosphohydrolase.
Low Prevalence of Coagulation and Fibrinolytic Activation in Patients with Primary Untreated Cancer
Authors: Nanninga P B , van Teunenbroek A , Veenhof C H N , Büller H R , ten Cate J W
Published: July 2018

The prevalence of subclinical coagulation abnormalities greatly differs in the various studies due to selection of patients and differences in study design. We performed coagulation studies in 69 consecutive patients with primary untreated cancer of various origin. The control group consisted of 42 sex and age matched healthy volunteers. Plasma coagulation tests included thrombin-antithrombin-III-complex (TAT), plasmin-alpha2-antiplasmin-complex (PAP) and tissue-plasminogen-activator-antigen (t-PA-ag). These tests were performed once, prior to any anti-cancer treatment. We evaluated if activation of the coagulation system (elevated TAT-complexes) and the fibrinolytic system (elevated PAP-complexes and t-PA-ag) correlated with the tumor-type or the extent of the tumor. To document clinical manifest haemorrhage or thromboembolic disease (TED) we performed a 6 months follow-up study.

In 8 patients (12%) and in 3 control subjects (7%) an elevated TAT-complex level was observed (this difference is not significant). An increased plasma level of PAP-complex was seen in 8 patients (12%) versus none in the control group (p <0.05). In one patient both TAT and PAP-complex concentrations were elevated. Consequently, 15 of the 69 patients (22%) showed activation of the coagulation and/or fibrinolytic system.

Fibrinolysis seems to be enhanced in a subset of cancer patients in contrast to blood coagulation.

In 10 patients (14%) we found raised t-PA-ag levels. Three patients had both elevated levels of PAP-complex and t-PA-ag. These findings suggest that in a minority of patients increased PAP-complex levels may be a result of t-PA induced plasminogen activation. No preferential association was found between tumortype and activation of these systems.

During follow-up we encountered in only 4 patients (6%) clinical evidence of haemorrhage or TED.

We conclude that a subclinical coagulopathy is present in approximately a fifth (22%, 95 percent confidence limits 13-33%) of untreated primary cancer patients.
Concomitant Secretion by A431 Cells of Tissue Plasminogen Activator and a Specific Inhibitor Masks EGF Modulation of tPA Activity
Authors: George F , Pourreau-Schneider N , Boutiere B , Arnoux D , Boutiére B , Berthois Y , Martin P M , Sampol J
Published: July 2018

It has previously been reported that EGF enhances uPA but not tPA in the A431 squamous carcinoma cell line. To determine whether the absence of tPA modulation by EGF reflected steady levels or the action of an anti-activator, we assayed tPA, PAI-1 and tPA/PAI-1 complexes by zymography and immunological assays. Under conditions in which EGF had no effect on tPA activity, tPA antigen paradoxically increased with a concomitant rise of tPA/PAI-1 complexes. This indicated that tPA was rapidly inactivated through the formation of a complex, immunologically and electrophoretically related to tPA/PAI-1. tPA antigen and tPA/PAI-1 complexes were modulated by EGF in a time and concentration dependent manner. PAI-1 antigen was secreted into A431 medium (CM) after a lag phase of 16 h in both control andEGF-treated cultures. Evidence is presented here that two forms ofPAI-1 are present in A431 CM: an inactive form and an active form which neutralizes the tPA secreted, masking its enhancement by EGF infunctional assays.
Scientific and Standardization Committee Communications Comparison of Test Methods for the Lupus Anticoagulant: International Survey on Lupus Anticoagulants-I (ISLA-1)
Authors: Exner Thomas , Triplett Douglas A , Taberner David A , Howard Margaret A , Harris E Nigel
Published: July 2018

Six lyophilized plasma samples were sent to 20 “expert” laboratories for assessment of lupus anticoagulant (LA). Four samples contained pooled LA of graded potency mixed with aged normal plasma. One contained LA plus cephalin phospholipid and one contained a nonspecific venom anticoagulant. Sixteen methods were used overall with some participants using up to 8 methods. Results were scored in regard to the known potencies of LA in the samples and other known induced defects.

Activated partial thromboplastin time (APTT) tests used by most participants for preliminary screening were relatively sensitive, but non-specific. Platelet or phospholipid neutralization procedures (PNP) appeared to be sensitive and specific but showed a non-linear response to increased LA content. Kaolin clotting time (KCT) tests showed the most sensitive response to increased LA content but the weaker LA were not scored as abnormal by most laboratories as the samples may have contained platelet fragments. Other commonly used tests such as the tissue thromboplastin inhibition (TTI) test and the dilute Russell’s viper venom test (DRVVT) were carried out somewhat inconsistently. The variability in performance of tests in different laboratories indicates that standardization of methodology is urgently required.

Generally it seemed that most clotting tests were “bypassed” by the addition of phospholipid to a known LA-positive sample in apparently direct proportion to their sensitivity. Sample preparation, especially prevention of contamination with activated platelets is a vital preliminary part in the assay of LA.
Regulation of Fibrinogen Synthesis in Portal Hypertension
Authors: Grün M , Liehr H , Brunswig D , Thiel H
Published: July 2018

The fibrinogen synthesis rate in patients with cirrhosis of the liver is enhanced. To confirm this, both experimental and clinical investigations were carried out. The fibrinogen synthesis rate was studied, using the incorporation rate of 14-C-Leucine into thrombin clottable plasma protein in the setting of experimental portal hypertension caused by gradual occlusion of the portal vein. Under these conditions the plasma distribution space increased to 148% of the control (day 6). This was dependent on the amount of the portocaval shunt volume. While plasma fibrinogen concentration remained unaltered, the plasma fibrinogen pool increased to 154% of the controls. At the same time, the fibrinogen synthesis rate increased to 159%. In relation to liver weight per 100 gm body weight the rate of synthesis was much more enhanced (211 % of control). During the decline to normal plasma volume, due to a decrease of portocaval shunt volume, the fibrinogen synthesis was inhibited (61% of control).

Under clinical conditions in patients with cirrhosis and portal hypertension, the pathophysiological state is in important aspects comparable to the experimental model. A group of 28 patients with cirrhosis was investigated from the same point of view. In these patients the plasma volume and the plasma fibrinogen pool was markedly increased, depending again on the portocaval shunt volume but not on the portal pressure. From these data it is concluded that in patients with cirrhosis fibrinogen synthesis is enhanced.
The Function of the Platelet Surface in Coagulation
Authors: Burnham King J
Published: July 2018

Platelets washed by the albumen density gradient technique were used as the sole source of thromboplastin in a new test, and also as the sole source of factor X in a modification of the one-stage factor X assay test of Denson. These platelets were shown to be capable of generating considerable amounts of thrombin during periods of preincubation of up to 8 minutes. For at least 3 minutes of preincubation their size and shape remained invariant, as measured by counting and by sizing on a Coulter channelyser. It is suggested that this test measures a function of the platelet surface, rather than of the platelet after viscous metamorphosis. This function is tentatively named platelet catalytic activity (PCA). Support for this concept was given by the fact that aspirin and phenylbutazone did not affect the test. The factor X assay system confirmed the presence of a small amount of mostly inactive factor X on the surface of the platelet. This factor X could be activated by Russell viper venom.
Streptokinase and Urokinase in the Treatment of Pulmonary Thromboemboli
Authors: Bell William R
Published: July 2018

In Phase I of this study of 160 patients with pulmonary embolism, it was demonstrated that 12 hours of urokinase accelerated the resolution of pulmonary thromboemboli compared to heparin alone. Phase II compared 12 hours of urokinase, 24 hours of urokinase and 24 hours of streptokinase in 167 patients. All patients had a clinical history and angiographic diagnosis of pulmonary embolism. Patients were randomly allocated to treatment. All physicians making patient observations were unaware of drug assignment.

Resolution of the thromboembolism 24–30 hours after therapy had been instituted was determined by pulmonary angiography, lung perfusion scans and cardiopulmonary hemodynamics. Twenty-four hours of urokinase did not demonstrate greater clot resolution than 12 hours of urokinase. Twenty-four hours of urokinase resulted in greater improvement than streptokinase in lung perfusion scans, but not in angiograms. In patients with massive embolism, this difference was statistically significant. Hemodynamic differences varied.

Bleeding complications and morbidity due to allergic reactions with streptokinase and urokinase were minimal. There was no statistically significant difference in mortality in the three treatment groups.

From the Phase I and Phase II data it is reasonable to conclude that all three regimens of thrombolytic therapy are more effective than heparin alone in accelerating resolution of pulmonary emboli. Thrombolytic therapy offers the clinician an alternative to pulmonary embolectomy.
Venous Diameter and Compliance after Deep Venous Thrombosis
Authors: Meissner Mark H , Manzo Richard A , Bergelin Robert O , Eugene Strandness D
Published: July 2018

Duplex sonography was used to measure diameters of the common femoral, superficial femoral, and popliteal veins in 56 patients followed for more than 6 months after DVT and in 17 normal subjects. Diameter changes with Valsalva’s maneuver were also measured as an index of venous compliance.

Among patients with unilateral thrombosis, segments with residual disease were 0.07 to 0.28 cm smaller than the contralateral disease-free side (p <0.05 for CFV and SFV) with a diameter index (ipsilateral/con-tralateral diameter) significanty less than that of normal subjects. In contrast, completely recanalized segments were not significantly different from the contralateral side and had diameter indices indistinguishable from normal subjects. Distensibility with Valsalva’s maneuver was not significantly different from normal in DVT patients with either resolved or residual disease.

Venous diameter does decrease following DVT, but returns to normal following complete recanalization and is not associated with chronic venous compliance changes.
Blood Coagulation and Fibrinolysis in a Random Sample of 788 Men 54 Years Old
Authors: Korsan-Bengtsen Kristoffer , Wilhelmsen Lars , Tibblin Gösta
Published: July 2018

Blood coagulation and fibrinolysis have been studied in a randomly selected population of 788 men 54 years of age. The mean values, standard deviations and distributions of recalcified plasma clotting time, PTT in silicone tubes and glass tubes, factor II-VII-X activity, factor VIII, fibrinogen, fibrinolytic activity in an euglobulin precipitation and plasminogen are presented. Linear regression analyses between the variables have been carried out. It was found that there is a significant correlation between fibrinogen and PTT in silicone tubes. An increased fibrinogen concentration thus tends to give prolonged clotting times. Factor VIII is negatively correlated to recalcified plasma clotting time and PTT in glass and silicone tubes. Increased factor VIII levels thus tend to shorten the clotting times. There is also a slight negative correlation between factor II-VII-X activity and PTT in glass tubes. In evaluating the significance of prolonged or shortened clotting times the inverse influence of fibrinogen and factor VIII on clotting time has to be considered. This is especially important in situations with increased frequency of thrombosis where both fibrinogen and factor VIII often are increased.
Continuous Subcutaneous Heparin Infusion During Pregnancy In A Patient With A Prosthetic Mitral Valve. Clinical And Laboratory Consideration
Authors: Messmore Harry L , Fareed Jawed , Hixon Barbara , Kniffin Judith , Squillaci Grace
Published: July 2018

Administration of heparin for prolonged periods during pregnancy has usually been by the intravenous route when full anticoagulant dosages are required. Bolus subcutaneous injection of heparin has also been used, however this requires medical supervision and proper laboratory control. We have administered heparin (Elkins - Sinn) to a pregnant patient by the subcutaneous route utilizing an infusion pump (Auto-Syringe RModel AS3A) for 15 weeks, maintaining an activated partial thromboplastin time (APTT) of approximately 50 sec (N=22-35) using “ACTIN” (Dade) brand ellagic acid cephaloplastin reagent. The average heparin dose has been 26,000 units/24 hours during the 4th to 19th week of her pregnancy. In order to establish the presence of circulating heparin we also performed Xa and thrombin-based amidolytic assays for the absolute levels of heparin in patient’s plasma. A poor correlation was seen between the heparin levels and the APTT values. These data indicate that absolute levels of heparin may not be taken as an index of heparinization in certain clinical conditions. Lack of serious complications and ease of administration has prompted us to continue heparin by this route during the remainder of her pregnancy.
Studies On The Effects Of Protamine On The Antithrombin III Heparin Complex
Authors: Okajima Y , Nakagawa M , Kitani T , Urano S , Hino R , Yoshikawa H , Ijichi H
Published: July 2018

Protamine has been employed as principal neutralizing agent for heparin but there are few reports on the effect of protamine to antithrombin III (AT 3III)-heparin complex, and this interaction was analyzed by means of column chromatography, crossed immunoelectrophoresis, and heparin sepharose affinity chromatography. Sephadex G-200 chromatography of heat defibrinated plasma treated with 3H- heparin revealed radioactivity in all protein fractions and protein free fraction. Immediate antithrombin activity was detected in AT III fractions. When the plasma treated with 3H labeled heparin was fractioned on sephadex G-200 after neutralization by protamine, most of radioactivity was eluted in the void volume and the radioactivity of other fractions was markedly decreased, and the immediate antithrombin activity was lost in any fractions and progressive antithrombin activity was detected in the third protein peak. Electrophoretic mobility of heparin treated AT III was increased depending to the heparin concentrations but when the heparinized plasma was neutralized with protamine, electrophoretic mobility of AT III was recovered. Meanwhile protamine treatment did not affect on the electro phoretic mobility of not heparinized control AT III. When AT III bound heparin sepharose was eluted with protamine solution and eluted fractions were chromatographed on sephadex G-75, AT III was separated from protamine. These results indicate that protamine dissociates AT III from AT III-heparin complex with binding to heparin and that the separated AT III recovers original progressive antithrombin activity.
Fluorometric Assay Of Low-Dose Plasma Heparin
Authors: OBrien P F
Published: July 2018

A modification of the fluorometric method for determining plasma heparin concentration in the range 0.10 to 0.80 IU/ml makes possible the assay of very low levels of heparin. The assay employs the synthetic fluorescent tripeptide, H-D-phe-pro-arg-5-amidoisophthalic acid, dimethyl ester, a thrombin substrate, and requires very small amounts of purified human thrombin and non-defibrinated plasma. The sensitivity is extended by increasing the volume of the plasma sample from 5 to 25 μl, and maintaining the incubation periods of the original high concentration method. The amount of thrombin not inhibited by the heparin-antithrombin III complex in the test solution liberates the fluorophore from the synthetic thrombin substrate in proportion to the heparin concentration in the test plasma. The calibration curve for heparin is linear in the range 0.006 to 0.200 IU/ml and is sufficiently steep to allow the precise, sensitive detection of very low levels of plasma heparin (with a coefficient of variation better than 5%). This method is useful in the determination of low-dose and ultra-low-dose heparin given by continuous infusion, or by subcutaneous or endotracheal administration.
Hyperfibrinolysis In A Patient With IgG-Paraproteinemia
Authors: Egbring R , Klingemann H G , Heimburger N , Karges H E , Havemann K
Published: July 2018

In patients with various malignancies (prostata, thyreoid, gastric), a hyperfibrinolytic syndrome has been described. We would like to give a report on a 56 year-old male patient who became clinically apparent by his spontaneous bleeding tendencies with large haematoma. Analysis of the coagulation status revealed a primary hyperfibrinolysis characterized by a prolonged TT and PTT, decreased fibrinogen (F I) and a simultaneous increase of FDP, associated with the consumption of F I. There was also a significant fall of plasminogen(Pig) and an alpha2-plasmin-inhibitor α2PI) down to about 10% of the norm. However, a Pig activator as a trigger of hyperfibrinolysis could not be detected in plasma, a malignoma could not be diagnosed. However, a IgG-paraproteinemia and uria associated with a 20% infiltration of bone marrow with plasma cells was assessed. The bleeding tendency was treated successfully with aprotinin (AntagosanR). Under the infusion (1 Mio KIU/d) a normalization of the coagulation status was observed as measured by means of the TT and PTT; simultaneously an increase of F I and the disappearance of FDP was observed. Pig and α2PI also rised but did not reach normal values. Based on these observations an interrelationship between hyperfibrinolysis and paraproteinemia appears to be possible.
Ristocetin - A New Tool in the Investigation of Platelet Aggregation
Authors: Howard Margaret A. , Firkin B. G
Published: July 2018

1. The antibotic, Ristocetin, causes precipitation of fibrinogen from platelet poor plasma, as well as platelet aggregation.

2. The precise mechanism of Ristocetin’s effect on platelets has not been elucidated, but it has been shown to initiate ADP release, which may contribute in part to its aggregating ability.

3. Ristocetin has been shown to produce aggregation in platelet rich plasma from thrombasthenic patients.

4. Three patients with Von Willebrand’s disease were examined. In 2, Ristocetin caused no platelet aggregation whatsoever, whilst the third aggregated normally. It is suggested, on this basis, that Von Willebrand’s disease may be subdivided into two types and that Ristocetin could prove to be a valuable technique for further study of this group of disorders.
Surface Factor Mechanisms in Relation to Blood Platelets: Evidence that Activated Hageman Factor is Present on the Surface of Platelets*
Authors: Iatridis P. G , Ferguson J. H , Iatridis S. G
Published: July 2018

Blood platelet suspensions from normal (N) or hemophilia A (VIII-) subjects contain active SF (surface factor or activation product) in their plasmatic atmosphere. Since factor XII is an essential precursor, SF is not formed on platelets from a Hageman-deficient. Experimental evidence establishing these facts was obtained by means of clotting tests (PCa and PTT) and the thrombelastograph (TEG). The SF activity of normal platelets, like a plasma SF preparation, corrects the deficiencies in XII- plasmas, best tested in silicone or the stainless steel cuvette of the TEG. An anti-SF preparation inhibited the platelet SF activity. Allowing for the SF effect, there was no evidence for any significant factor VIII (AHF) in the platelet plasmatic atmospheres.

How surface factor (SF) activation from precursors (XII, XI) in the plasma and plasmatic atmosphere of altering platelets may combine in a mutually reinforcing reaction to trigger intrinsic blood clotting is discussed. When stress, vascular injury, stasis, and other factors enter the picture, the stage may be set for the occurrence of thrombosis in vivo.
Purification and Kinetic Studies on a Circulating Anticoagulant in a Suspected Case of Lupus Erythematosus*
Authors: Yin E. T , Gaston L. W
Published: July 2018

1. A circulating anticoagulant in a suspected case of lupus erythematosus has been highly purified by a combination of Sephadex gel filtration and DEAE cellulose chromatography.

2. The inhibitor is a gamma globulin with a sedimentation coefficient of 6.6 Svedberg units.

3. For its anticoagulant action, the lupus inhibitor requires a co-factor which is present both in the lupus and normal blood.

4. The cofactor is located in the gamma globulins fraction which is relatively heat stable, but less than the inhibitor, at 56° C.

5. The active lupus inhibitor (inhibitor + cofactor) is not species specific against human prothrombin.

6. Working with highly purified systems, the active inhibitor is found to inhibit prothrombin conversion by formed prothrombin activator. It does not appear to inhibit the formation of prothrombin activator nor does it affect purified prothrombin.
Assay and Content of Tissue Thromboplastin in Different Organs*
Authors: Astrup T
Published: July 2018

1. The assay of thromboplastin in tissues in terms of units of concentration by means of the double logarithmic graph is described and discussed. The significance of comparing thromboplastin in terms of concentrations and not in terms of activities is explained.

2. The concentration of thromboplastin in some human and animal organs is estimated. Great variations are encountered in concentrations. The differences are larger than is generally assumed from activity assays only. The possible role of these differences in the local repair of tissue injuries as part of the hemostatic balance is mentioned.
Studies on Thrombin Inactivation in Normal Plasma, Serum and Plasma Fractions, and its Relation to Heparin
Authors: Blombäck Birger , Blombäck Margareta , Olsson Per
Published: July 2018

The antithrombin activity of plasma, serum and plasma fractions has been studied under different experimental conditions. Two different methods have been used for the assay of antithrombin activity.

Under the experimental conditions described the following antithrombin activities have been found to be of importance in the inactivation of thrombin:

1. Progressive inactivation in the absence of heparin can take place in plasma and to a less extent in defibrinated plasma and serum.

2. Inactivation of thrombin in presence of fibrinogen and heparin in low concentration (about 0.03 I.U./ml). This effect was abolished at high heparin levels.

3. Inactivation of thrombin by plasma, defibrinated plasma and serum at high concentrations of heparin (about 2—15 I.U./ml). This activity is tentatively named the heparin co-factor.
Addition of Prothrombin to Blood from Dogs Receiving Dicumarol
Authors: Schröer Heinz , Heene D. L , Seegers W. H
Published: July 2018

The prothrombin concentration of dog plasma was lowered by giving large doses of Dicumarol. The dog blood was then mixed with progressive increments of purified bovine prothrombin. When the concentration of prothrombin was equivalent to normal the whole blood clotting time and the prothrombin time were normal. The purified prothrombin supplied all that was essential and did not add detectable amounts of extraneous pro coagulant power. The residual prothrombin in the serum was generally higher when clotting occurred in silicone lined test tubes than in glass. In silicone tubes very little hemophilia B (factor IX, autoprothrombin II) activity developed. This activity was found in the glass tubes in a concentration proportional to the original prothrombin added. The transformation of prothrombin to autoprothrombin II occurred in plasma when there was a glass surface.
Thyroid Disorders and Hemostasis
Authors: Squizzato Alessandro , Gerdes Victor , Elbers Laura
Published: July 2018

Lower levels of free thyroxine (whether this is endogenous or exogenous) lead to a hypocoagulable state, and higher levels of free thyroxine lead to a hypercoagulable state. In this narrative review, the effects of different levels of thyroid hormones on clinical end points are described. Hypothyroidism is associated with an increased bleeding risk, whereas hyperthyroidism leads to an increased risk of venous thrombosis. Besides, effects of thyroid hormone on the heart may indirectly influence hemostasis. Hyperthyroidism leads to a higher incidence of atrial fibrillation and atrial flutter, and, at least partly by that mechanism, a higher risk of cerebral arterial thrombosis. In addition, compression effects of goiter on developing venous thrombosis are described. This is caused by local stasis of blood due to tumor expansion.
Superscar states in rational polygon billiards—A reality or an illusion?
Authors: Giller Stefan
Published: July 2018

The superscars phenomena [Heller, E. J., Phys. Rev. Lett. 53, 1515 (1984)] in the rational polygon billiards (RPBs) are analyzed using the high energy semiclassical wave functions (SWFs) built on classical trajectories forming skeletons. Considering examples of the pseudointegrable billiards such as the Bogomolny-Schmit triangle, the parallelogram, and the L-shape billiards as well as the integrable rectangular one, the constructed SWFs allow us to verify the idea of Bogomolny and Schmit [Phys. Rev. Lett. 92, 244102 (2004)] of SWFs (superscars) propagating along periodic orbit channels (POCs) and vanishing outside of them. It is shown that the superscars effects in RPBs appear as natural properties of SWFs built on the periodic skeletons. The latter skeletons are commonly present in RPBs and are always composed of POCs. The SWFs built on the periodic skeletons satisfy all the basic principles of the quantum mechanics contrary to the superscar states of Bogomolny and Schmit which break them. Therefore, the superscars effects need not to invoke the idea of the superscar states of Bogomolny and Schmit at least in the cases considered in our paper.
Improved control strategy of DFIG-based wind turbines using direct torque and direct power control techniques
Authors: Kouadria Selman , Berkouk El Madjid , Messlem Youcef , Denaï Mouloud
Published: July 2018

This paper presents different control strategies for a variable-speed wind energy conversion system (WECS), based on a doubly fed induction generator. Direct Torque Control (DTC) with Space-Vector Modulation is used on the rotor side converter. This control method is known to reduce the fluctuations of the torque and flux at low speeds in contrast to the classical DTC, where the frequency of switching is uncontrollable. The reference for torque is obtained from the maximum power point tracking technique of the wind turbine. For the grid-side converter, a fuzzy direct power control is proposed for the control of the instantaneous active and reactive power. Simulation results of the WECS are presented to compare the performance of the proposed and classical control approaches.
Ionic liquids make DNA rigid
Authors: Garai Ashok , Ghoshdastidar Debostuti , Senapati Sanjib , Maiti Prabal K.
Published: July 2018

Persistence length of double-stranded DNA (dsDNA) is known to decrease with an increase in ionic concentration of the solution. In contrast to this, here we show that the persistence length of dsDNA increases dramatically as a function of ionic liquid (IL) concentration. Using all atom explicit solvent molecular dynamics simulations and theoretical models, we present, for the first time, a systematic study to determine the mechanical properties of dsDNA in various hydrated ILs at different concentrations. We find that dsDNA in 50 wt % ILs have lower persistence length and stretch modulus in comparison to 80 wt % ILs. We further observe that both the persistence length and stretch modulus of dsDNA increase as we increase the concentration of ILs. The present trend of the stretch modulus and persistence length of dsDNA with IL concentration supports the predictions of the macroscopic elastic theory, in contrast to the behavior exhibited by dsDNA in monovalent salt. Our study further suggests the preferable ILs that can be used for maintaining DNA stability during long-term storage.
Reciprocal transformation of seniority number restricted wave function
Authors: Zhou Chen , Chen Zhenhua , Wu Wei
Published: July 2018

In this work, an extension of Malmqvist’s algorithm is efficiently implemented for the reciprocal transformation of a seniority number restricted multideterminant wave function constructed by nonorthogonal orbitals to an equivalent one constructed by biorthogonal orbitals. Test calculations show that the novel algorithm is capable of applying to transform quite large nonorthogonal orbital based wave function of distributing 22 electrons on 22 orbitals with the maximum seniority number sector and for the evaluation of a three-body operator, at an affordable memory cost of about 800 GB, which is only about one tenth of the size of the corresponding complete active space. Moreover, the algorithm displays improved computational efficiency, due to the compactness of seniority number restricted multi-determinant wave functions.
An electron Bernstein wave heating scheme for the Proto-MPEX linear device
Authors: Diem S. J. , Green D. L. , Harvey R. W. , Petrov Yu. V.
Published: July 2018

Linear plasma devices, such as the Prototype Material Plasma Exposure eXperiment (Proto-MPEX), are an economic method to study plasma-material interactions under high heat and particle fluxes. The Proto-MPEX device at Oak Ridge National Laboratory is a high-density helicon plasma generator with additional resonant electron heating to study plasma-material interactions in ITER-like conditions. Here, we present modeling results of an electron Bernstein wave (EBW) heating scheme for this device using a microwave-based system. A 28 GHz injection system is available to provide power levels up to 100 kW injected into low electron temperature and high electron density plasmas. A modified version of the GENRAY ray-tracing code, GENRAY-C, has been used to determine the EBW and electron cyclotron heating wave accessibility for these overdense plasmas. Modeling has shown that greater than 80% of mode conversion from the ordinary mode to the EBW is possible for 28 GHz injection in Proto-MPEX. Calculations show that by utilizing the effects of Doppler-shifted resonance absorption, power deposition near the core is possible. Significant collisional damping, leading to edge absorption, is expected to occur for neutral pressures >1.0 mTorr; however, experiments can be designed to minimize these effects.
Turbulence measurements on the high and low magnetic field side of the DIII-D tokamak
Authors: Sung C. , Rhodes T. L. , Peebles W. A.
Published: July 2018

In this paper, we address the challenging question of measuring turbulence levels on the high magnetic field side (HFS) of tokamak plasmas. Although turbulence measurements on the HFS can provide a stringent constraint for the turbulence model validation, to date only low magnetic field side (LFS) measured turbulence has been used in validation studies. To address this issue, an eight channel Correlation Electron Cyclotron Emission (CECE) system at DIII-D was modified to probe both LFS and HFS. In contrast to the second harmonic extraordinary mode electron cyclotron resonance emission that is typically used in CECE, we show that it is possible to probe the HFS using fundamental O-mode electron cyclotron resonance emission. The required hardware modifications for the HFS measurements are presented here, and the potential issues in this measurement are discussed.
Reduced scaling CASPT2 using supporting subspaces and tensor hyper-contraction
Authors: Song Chenchen , Martínez Todd J.
Published: July 2018

We present a reduced scaling formulation of the state specific complete active space second-order perturbation method (CASPT2) requiring O(N4) operations and O(N2) memory for a fixed active space, where N is proportional to system size. Motivated by the properties of the Kronecker sum, we introduce the supporting subspace technique (SST), which decomposes the CASPT2 linear equations into two parts: a single-reference MP2 energy term using dressed orbitals, plus a reduced linear system with dimension scaling as O(N2). Together with Laplace quadrature, the SST allows us to reformulate CASPT2 using a MP2 energy computation and Fock builds. By further applying the tensor hyper-contraction (THC) approximation, the MP2-like term can be computed with O(N4) operations, and the remainder can be solved with O(N3) operations using the preconditioned conjugate gradient method. This is the first application of THC in the context of multi-reference methods. We also developed an efficient implementation of the method by utilizing graphical processing units and exploiting spatial sparsity in tensor operations. We benchmark the accuracy of the new method against conventional CASPT2 for reactions in the gas phase. We apply the new method to Menshutkin SN2 reactions in carbon nanotubes, demonstrating the feasibility of CASPT2 calculations with O(100) atoms.
Monte-Carlo study of electronic transport in non-σh-symmetric two-dimensional materials: Silicene and germanene
Authors: Gaddemane Gautam , Vandenberghe William G. , Van de Put Maarten L. , Chen Edward , Fischetti Massimo V.
Published: July 2018

The critical role of silicon and germanium in the semiconductor industry, combined with the need for extremely thin channels for scaled electronic devices, has motivated research towards monolayer silicon (silicene) and monolayer germanium (germanene). The lack of horizontal mirror (σh) symmetry in these two-dimensional crystals results in a very strong coupling—in principle diverging—of electrons to long wavelength flexural branch (ZA) phonons. For semi-metallic Dirac materials lacking σh symmetry, like silicene and germanene, this effect is further exacerbated by strong back-scattering at the Dirac cone. In order to gauge the intrinsic transport limitations of silicene and germanene, we perform low- and high-field transport studies using first-principles Monte-Carlo simulations. We take into account the full band structure and solve the electron-phonon matrix elements to treat correctly the material anisotropy and wavefunction overlap-integral effects. We avoid the divergence of the ZA phonon scattering rate through the introduction of an optimistic (1 nm long wavelength) cutoff for the ZA phonons. Even with this cutoff for long-wavelength ZA phonons, essentially prohibiting intravalley scattering, we observe that intervalley ZA phonon scattering dominates the overall transport properties. We obtain relatively large electron mobilities of 701 cm2 V−1 s−1 for silicene and 2327 cm2 V−1 s−1 for germanene. Our results show that silicene and germanene may exhibit electronic transport properties that could surpass those of many other two-dimensional materials, if intravalley ZA phonon scattering could be suppressed.
Finite time blowup and global solutions of Euler type equations in matrix geometry
Authors: Li Jiaojiao , Ma Li
Published: July 2018

In an interesting recent work, Professor Sullivan has proposed a matrix version of the Euler equation to approach this problem from a new angle. Motivated by his work, we consider the finite time blowup and global solutions of Euler type equations in the matrix geometry. We set up some invariant sets of the flow equations, and the invariant sets are defined via the use of the free energy functional and the Nehari functional in the matrix geometry model. The blowup result is obtained by the convexity method.
Enhanced magnetic modulation in HfO2-based resistive memory with an Hf top electrode
Authors: Guo Jiajun , Kang Xin , Gao Yingjie , Chen Wei , Zhao Xu
Published: July 2018

Magnetic modulation in binary-oxide-based resistive random access memory (RRAM) shows promise for applications in future electronics. However, the small magnetization change and large operating voltage in undoped binary oxide films make its practical applications difficult. In this study, we investigated magnetic switching behaviors in RRAM devices based on HfO2 film utilizing either Ti or Hf as the top electrode (TE). Substantially enhanced magnetic modulation and reduced operating voltage of the HfO2 film is demonstrated in the device using an Hf TE. The saturation magnetization of the HfO2 film is more than four times larger in a low resistance state than in a high resistance state under a set/reset voltage of only 0.4/0.3 V. We propose that these results are related to two factors: the high standard Gibbs energy of oxide formation for metal Hf; and the dual ion diffusion of hafnium (originating from the Hf TE) and oxygen in the device. This work shows that selecting a suitable TE can result in enhanced capability for electrical control of magnetism in metal oxides.
Carrier injection in organic electronics: Injection hotspot effect beyond barrier reduction effect
Authors: Lu Zhi-Hao , Hu Jia-Xin , Zhong Ya-Nan , Zhou Xu , Xu Chao , Gao Xu , Xu Jian-Long , Duhm Steffen , Wang Sui-Dong
Published: July 2018

An alternative strategy, making a number of injection hotspots at the nanoscale on the electrode surface to reinforce the local electric field, is proposed for achieving efficient carrier injection in organic electronic/optoelectronic devices. The injection hotspot effect can be dominant at the metal/organic contacts with a high carrier injection barrier, when the barrier reduction effect is not applicable. In the present case, a tiny amount of fullerene and its derivative on ITO do not significantly change the injection barrier but form the injection hotspots which enhance the electron injection and greatly reduce the operation voltage in the inverted organic light-emitting diodes.
Perspective: Coherent Raman scattering microscopy, the future is bright
Authors: Zhang Chi , Cheng Ji-Xin
Published: July 2018

Chemical imaging offers critical information to understand the fundamentals in biology and to assist clinical diagnostics. Label-free chemical imaging piques a general interest since it avoids the use of bio-perturbing molecular labels and holds promises to characterize human tissue in vivo. Coherent Raman scattering (CRS), which utilizes lasers to excite the vibrations of molecules, renders new modalities to map chemicals in living samples without the need of labeling and provides significantly improved speed, resolution, and sensitivity compared to spontaneous Raman scattering. Although microscopy systems based on CRS have seen rapid development in the past two decades, remaining challenges, which emerge in diverse aspects, start to impede the continuous advancement of the field. In this perspective, we review the history of CRS microscopy, scrutinize the pros and cons of different modalities, and discuss the current challenges and possible future directions of the field. Infiltration of conceptual and technological ideals from other fields will promote CRS microscopy towards a versatile tool for basic science and medical research.
A molecular equation of state for alcohols which includes steric hindrance in hydrogen bonding
Authors: Marshall Bennett D.
Published: July 2018

In this paper, we develop the first equation of state for alcohol containing mixtures which includes the effect of steric hindrance between the two electron lone pair hydrogen bond acceptor sites on the alcohol’s hydroxyl oxygen. The theory is derived for multi-component mixtures within Wertheim’s multi-density statistical mechanics in a second order perturbation theory. The accuracy of the new approach is demonstrated by application to pure methanol and ethanol and binary ethanol/water mixtures. It is demonstrated that the new approach gives a substantial improvement in the prediction of the hydrogen bonding structure of both pure alcohol and alcohol/water mixtures, as compared to conventional approaches which do not include steric effects between the alcohol association sites. Finally, it is demonstrated that the inclusion of steric effects allows for more accurate binary phase equilibria and heats of mixing prediction with water.
A GaN–SiC hybrid material for high-frequency and power electronics
Authors: Chen Jr-Tai , Bergsten Johan , Lu Jun , Janzén Erik , Thorsell Mattias , Hultman Lars , Rorsman Niklas , Kordina Olof
Published: July 2018

We demonstrate that 3.5% in-plane lattice mismatch between GaN (0001) epitaxial layers and SiC (0001) substrates can be accommodated without triggering extended defects over large areas using a grain-boundary-free AlN nucleation layer (NL). Defect formation in the initial epitaxial growth phase is thus significantly alleviated, confirmed by various characterization techniques. As a result, a high-quality 0.2-μm thin GaN layer can be grown on the AlN NL and directly serve as a channel layer in power devices, like high electron mobility transistors (HEMTs). The channel electrons exhibit a state-of-the-art mobility of >2000 cm2/V-s, in the AlGaN/GaN heterostructures without a conventional thick C- or Fe-doped buffer layer. The highly scaled transistor processed on the heterostructure with a nearly perfect GaN–SiC interface shows excellent DC and microwave performances. A peak RF power density of 5.8 W/mm was obtained at VDSQ = 40 V and a fundamental frequency of 30 GHz. Moreover, an unpassivated 0.2-μm GaN/AlN/SiC stack shows lateral and vertical breakdowns at 1.5 kV. Perfecting the GaN–SiC interface enables a GaN–SiC hybrid material that combines the high-electron-velocity thin GaN with the high-breakdown bulk SiC, which promises further advances in a wide spectrum of high-frequency and power electronics.
Shallow electron traps formed by Gd2+ ions adjacent to oxygen vacancies in cerium-doped Gd3Al2Ga3O12 crystals
Authors: Kitaura Mamoru , Watanabe Shinta , Kamada Kei , Jin Kim Kyoung , Yoshino Masao , Kurosawa Shunsuke , Yagihashi Toru , Ohnishi Akimasa , Hara Kazuhiko
Published: July 2018

To clarify the origin of shallow electron traps in cerium-doped Gd3Al2Ga3O12 (Ce:GAGG), the optical properties of cerium-doped Lu3−xGdxAl2Ga3O12 crystals were investigated. Absorption spectra for x = 3 exhibited a prominent band at 12 000 cm−1 when excited by 3.31-eV ultraviolet light. This band has been previously attributed to shallow electron traps at defect complexes associated with oxygen vacancies. When Gd3+ ions were replaced with Lu3+ ions, the 12 000 cm−1 band weakened and disappeared completely for Ce:Lu3Al2Ga3O12. In addition, thermally stimulated luminescence glow curves were observed. Optically stimulated luminescence indicated that the energy of the conduction band minimum did not change by the presence of Lu3+ ions. Thus, the Gd3+ ions were important for the formation of shallow electron traps in Ce:GAGG. First-principles calculations implied that Gd3+ ions responsible for shallow electron traps formed antisite defects at GAGG octahedral sites. Hence, defect complexes of antisite Gd2+ ions adjacent to oxygen vacancies were the most plausible candidates for shallow electron traps in Ce:GAGG.
Visible Light-Induced CO-Release Reactivity of a Series of ZnII–Flavonolate Complexes
Authors: Su Yuanyuan , Yang Weixing , Yang Xu , Zhang Ronglan , Zhao Jianshe
Published: July 2018

A series of zinc–flavonolate complexes of the general formula [(L)Zn(R)]ClO4 (L = TPA (tris-2-(pyridylmethyl)amine)), 6-MeTPA (N,N-(6-methyl-2-pyridyl)methyl)bis(2-pyridylmethyl)amine)), 6-Me2TPA (N,N-bis(6-methyl-2-pyridyl)methyl)(2-pyridylmethyl) amine), BPQA (bis(2-pyridylmethyl)(2-quinolinemethyl)amine), and BQPA (bis(2-quinolinemethyl)(2-pyridylmethyl)amine), R = FLH (flavonol), 4-MeOFLH (4-methoxyflavonol), and 4-MeOFLTH (4-methoxyflavothione)) have been prepared and characterised by X-ray crystallography, elemental analysis, FT-IR, ESI-MS, 1H NMR, 13C NMR, UV-vis and fluorescence spectroscopy. All the complexes can be induced to release CO by visible light (λmax ranges from 414 to 503 nm). The maximum absorption wavelength of the complexes followed the order 4-MeOFLTH > 4-MeOFLH > FLH. Exposure of the complexes to visible light under aerobic conditions results in oxidative C–C bond cleavage and almost quantitative CO release. Cytotoxicity tests showed that the complexes had a low toxicity to HeLa cells in the concentration range of 1 to 50 μM. These advantages indicate that the series of complexes are likely to be applied to biological systems.
Nonverbal predication in Paresi-Haliti
Authors: Brandão Ana Paula
Published: July 2018

The Paresi people, who number approximately 3000, live in Mato Grosso, Brazil. The following types of predicates are found: nominal, adjectival, locational, existential and possessive predicates. There are three types of strategies used: verbless predicates, the use of the copula tyaona, and the use of prefixes. The source of the copula may be its homonymous form tyaona ‘live, be born, happen’. It has a more restricted use in nominal and adjectival predicates, with the meaning ‘become’ (similar to a semi-copula), and takes aspectual markers. Nominal predicates can be further semantically classified into identity or predicational statements (Stassen 1997). In locative predicates, a copula is used when the the personal proclitics are used instead of full noun phrases. Existential predicates are formed by the existential verb aka. Possessive predicates are formed by prefixes, a strategy which is not common cross-linguistically. They may be derived from inalienable (plant parts and kinship terms) and alienable nouns through the attributive ka-. Its negative counterpart, the prefix ma-, derives private stative predicates from nouns and stative verbs.