bluuebunny/crossref_metadata_2025 huggingface dataset:
Diagnosis of Hemophilia B Carriers Using Two Novel Dinucleotide Polymorphisms and Hha I RFLP of the Factor IX Gene in Japanese Subjects
Authors: Toyozumi Hisato , Kojima Tetsuhito , Matsushita Tadashi , Hamaguchi Motohiro , Tanimoto Mitsune , Saito Hidehiko
Published: July 2018

We identified two novel dinucleotide polymorphisms in intron A at nucleotide 192 (FIX 192) and in the 5’ flanking region at nucleotide -793 (FIX-793) of the factor IX gene, which are present in normal Japanese. The Hha I restriction fragment length polymorphism (FIX-Hhal) located 8 kb 3’ to the factor IX gene was also found to be an efficient marker for detecting carriers in a Japanese family with hemophilia B. Each of these polymorphisms was able to be rapidly ascertained by the polymerase chain reaction (PCR) technique. In 22 Japanese families with hemophilia B, 18 families (81.8%) were heterozygous for at least one of these polymorphisms, whereas 11 (50%) were informative for the extragenic DXS99/Sac I RFLP which was previously reported as a useful gene marker for Japanese hemophilia B. Using all 4 polymorphisms together, the informative rate improved to 86.4%. Carrier detection and, possibly, the prenatal diagnosis of hemophilia B can be achieved effectively and rapidly in Japanese with these polymorphisms.
Thromboxane Biosynthesis, Neutrophil and Coagulative Activation in Type IIa Hypercholesterolemia
Authors: Davì Giovanni , Ganci Antonina , Averna Maurizio , Giammarresi Carlo , Barbagallo Carlo , Catalano Isabella , Calà Anna , Notarbartolo Alberto
Published: July 2018

Thromboxane (Tx) A2 biosynthesis is enhanced in the majority of patients with type IIa hypercholesterolemia. Because blood clotting activation is an important component of the inflammatory response, involved in the initiation and progression of atherosclerotic plaques, we have investigated TxA2 biosynthesis, neutrophil activation and thrombin generation in 24 patients with type IIa hypercholesterolemia.

Urinary 11-dehydro-TxB2, was significantly higher (p =0.0001) in patients than in 24 sex- and age matched healthy subjects. Similarly, prothrombin fragment 1+2 (F1+2), thrombin-antithrombin III complexes and plasma elastase were significantly higher in patients than incontrols. Urinary 11-dehydro-TxB2 excretion was correlated with plasma elastase (r = 0.758; p =0.000I), and prothrombin fragment 1+2 (r = 0.804; p = 0.001). The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor simvastatin (20 mg/day for 2 months) significantly reduced cholesterol levels, urinary 11-dehydro-TxB2 excretion, plasma elastase and plasma Fl+2 in 8 patients.

We conclude that type IIa hypercholesterolemia is associated with biochemical evidence of platelet, neutrophil and blood clotting activation. The relationship between these events remains to be investigated.
Mechanisms of Platelet Dysfunction and Response to DDAVP in Patients with Congenital Platelet Function Defects
Authors: Rao A Koneti , Ghosh Sikha , Sun Ling , Yang Xu , Disa Jyoti , Pickens Peter , Polansky Marcia
Published: July 2018

To examine the impact of the underlying defective platelet mechanism on the response to 1-desamino-8-D-arginine vasopressin (DDAVP, Desmopressin), we studied the effect of intravenous infusion of 0.3 μg/kg of DDAVP in a randomized double blind placebo-controlled trial with cross-over in 18 carefully characterized patients with congenital platelet defects (CPD) and BT ≥9 min. Eleven patients had normal dense granule stores and normal thromboxane A2 (TxA2) production (Group I), 3 patients had normal granule stores but impaired TxA2 production (Group II), and 4 had δ-storage pool deficiency (Group III). DDAVP shortened BT at 50 min (DDAVP 14.6 ± 2.2 vs placebo 19.6 ± 2.3 min; n = 18; mean ± SE; p = 0.003) and 4h (17.0 ± 2.2 vs 19.6 ±2.1 min, p = 0.055), and raised plasma FVIIIC and von Willebrand factor (vWF). At 50 min DDAVP shortened BT by ≥5 min in 8 of 11 Group I patients (mean 9.7 ± 1.3 vs 16.3 ± 2.8 min; p <0.008), 1 of 3 Group II patients (11.9 ± 3.9 vs 17.7 ± 6.6; p = NS) and none of Group III patients (mean 30 min both arms). Ten patients (Group I or II) were managed successfully during surgical procedures with DDAVP alone. We conclude that DDAVP shortens BT in majority of CPD patients with normal dense granule stores and suggest that BT response may be dependent on the underlying platelet defect. DDAVP is a useful modality in management of selected patients, particularly those with normal dense granule stores.
Biological Effects of Combined Inactivation of Plasminogen Activator and Plasminogen Activator Inhibitor-1 Gene Function in Mice
Authors: Lijnen H Roger , Moons Lieve , Beelen Veerle , Carmeliet Peter , Collen Désiré
Published: July 2018

Mice with combined homozygous deficiency of tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA) (T‾U‾), of t-PA and plasminogen activator inhibitor-1 (PAI-1) (T‾P‾), of u-PA and PAI-1 (U‾P‾) or of t-PA, u-PA, and PAI-1 (T‾U‾P‾) were generated by inbreeding of mice with the respective deficiencies. Homologous recombination at the t-PA, u-PA and PAI-1 locus was verified by Southern blot analysis of genomic tail tip DNA, and confirmed by measurement of antigen levels in plasma or urine.

T‾P‾ and U‾P‾ mice were apparently healthy and fertile. T‾U‾ mice showed extensive fibrin deposition with calcification in the liver, whereas T‾U‾P‾ mice were significantly (p <0.001) less affected. Spontaneous in vivo clot lysis measured 4 h after injection of a 125I-fibrin-labeled clot prepared from plasma of wild-type (WT) mice into the jugular vein, was (mean ± SEM of n experiments) 2 ± 1% (n = 8) for T P , 49 ± 6% (n = 9) for U‾P‾, 1 ± 1% (n = 4) for T‾U‾ and 3 ± 3% (n = 3) for TU‾P‾ mice, as compared to 32 ± 4% (n = 10) for WT, 1 ± 0% (n = 7) for T‾, 30 ± 5% (n = 5) for U‾ and 58 ± 10% (n = 6) for P‾ mice. Plasminogen-dependent lysis of 125I-fibrin-labeled matrix and of 3H-proline-labeled subendothelial matrix (mean ± SEM; n = 4 to 6) was lower with thioglycollate-stimulated macrophages obtained from U‾P‾ mice (22 ± 7% and 5 ± 1%, respectively), as compared to WT mice (57 ± 14% and 18 ± 5%, respectively) and T‾P‾ mice (87 ± 6% and 27 ± 4%, respectively). A similar decrease was previously observed with U‾ mice, but not with T‾ or P‾ mice. Thus, the phenotype of mice with combined deficiency of t-PA and PAI-1 or of u-PA and PAI-1 is similar to the phenotype observed in mice with single deficiency of the plasminogen activator. Additional deletion of PAI-1 does not affect viability, fertility, macrophage function or thrombolytic potential of the single deficient mice. Additional deletion of PAI in mice with combined deficiency of t-PA and u-PA does not restore the deficient in vivo fibrinolytic capacity, but significantly reduces the thrombotic phenotype, as revealed by fewer, smaller and less calcified fibrin deposits in the liver.
Inhibition of Platelet Aggregation by an SLE-Derived Human Hybridoma Autoantibody Against an Activation-Dependent Antigen
Authors: Xu H , Frojmovic M M , Wong T , Rauch J
Published: July 2018

Anti-platelet autoantibodies may be responsible for hematological complications in patients with systemic lupus erythematosus (SLE), but the mechanisms by which these antibodies cause abnormal hemostasis remain unknown. In the present study, using fluorescence activated cell sorter (FACS) analysis, we demonstrate that an SLE-derived human hybridoma autoantibody, 9604, recognizes a surface antigen expressed on platelets activated by ADP, calcium ionophore A23187, or phorbol myristate acetate (PMA), showing saturation with approximately 2,000 antibody molecules bound per platelet and a Kd of 41 nM. The binding of 9604 to activated platelets was significantly inhibited by EDTA, indicating partial dependence on divalent cations. It did not appear to be dependent on platelet secretion, nor did it directly affect α-granule or dense granule secretion. The protein antigen responsible for the binding of 9604 to activated platelets was characterized by Western blot and immunoprccipitation and shown to have a native molecular weight (M. W.) of greater than 400,000, with a 32,000 M. W. subunit (p 32). Antibody 9604 had little or no effect on the shape change and the initial rate of primary aggregation of normal platelets. In contrast, 9604 inhibited secondary aggregation of stirred platelet suspensions (IC50 ≥1 nM) following activation by ADP, thromboxane A2 mimetic U46619, or calcium ionophore A23187, but not PMA or thrombin. The inhibition of large platelet aggregate formation (secondary aggregation), with a major shift to smaller microaggregates and singlets, was confirmed by direct particle count and sizing studies. The functional inhibition of platelet aggregation by an SLE-derived human hybridoma autoantibody in vitro suggests one potential mechanism that may play a role in the hemostatic disorders found in SLE.
Decreased Plasma Tissue Factor Pathway Inhibitor Levels in Patients with Thrombotic Thrombocytopenic Purpura
Authors: Wada Hideo , Kobayashi Masayuki , Wakita Yoshihiro , Shimura Minori , Nakase Tutomu , Hiyoyama Katsuyo , Nagaya Syousaburou , Minami Nobuyuki , Nakano Takeshi , Shiku Hiroshi
Published: July 2018

We measured plasma levels of tissue factor (TF) and tissue factor pathway inhibitor (TFPI) in patients with thrombotic thrombocytopenic purpura (TTP) and disseminated intravascular coagulation (DIC) to examine the relationship between TFPI and vascular endothelial cell injury. TF antigen was detected in the plasma of healthy volunteers, and the levels were significantly increased in the patients with DIC, but decreased slightly in those with TTP. Plasma TFPI levels were significantly decreased in patients with TTP compared with those in healthy volunteers. The concentration of plasma thrombomodulin (TM) antigen was significantly higher in those with TTP than in normal volunteers. One month after treatment, TTP patients showed a significant decrease in plasma TM levels, and a significant increase, in plasma TFPI levels, but plasma levels of TF antigen were not significantly increased. As plasma TFPI/TF ratio was significantly increased after treatment, the hypercoagulable state was therefore improved after treatment. There was no significant difference in plasma TF and TFPI levels between those who achieved complete remission (CR) and those who died. However, plasma TM levels were significantly higher in those who died than in those who achieved CR. Plasma TFPI levels might reflect injury of vascular endothelial cells as do plasma TM levels, and decreased plasma TFPI/TF ratio and vascular endothelial cell injuries might play causative roles in TTP.
Application of a Novel and Rapid Whole Blood Assay for D-Dimer in Patients with Clinically Suspected Pulmonary Embolism
Authors: Ginsberg Jeffrey S , Wells Philip S , Brill-Edwards Patrick , Donovan Dianne , Panju Akbar , van Beek Edwin J R , Patel Ameen
Published: July 2018

Study Objective: To determine the clinical utility of a novel whole blood assay for D-dimer (SimpliRED™) in patients with clinically suspected pulmonary embolism (PE).

Design: Prospective cohort.

Patients: Eighty-six consecutive patients with clinically suspected PE.

Intervention: All patients had the SimpliRED D-dimer assay performed and underwent ventilation/perfusion (V/Q) lung scanning and bilateral impedance plethysmography (IPG); pulmonary angiography was performed in two patients. Patients were classified as: 1) PE-positive; positive pulmonary angiography or high probability V/Q scan or non-high probability V/Q scan and either abnormal IPG (either at presentation or upon serial testing and confirmed by contrast venography) or symptomatic thromboembolic event within three months of presentation or 2) PE-negative; normal V/Q scan or normal pulmonary angiography or non-high probability V/Q scan and normal serial IPG and absence of symptomatic venous thromboembolism within three months of follow up. Sixteen (19%) patients were classified as PE-positive and 70 (81%) patients were classified as PE-negative.

Measurements and Result: The sensitivities, specificities, positive predictive values, and negative predictive values of the D-dimer assay were calculated for all patients and for the subgroup of patients without comorbid conditions that independently can cause elevated D-dimer levels. The D-dimer showed a sensitivity of 94%, a negative predictive value of 98%, a specificity of 66%, and a positive predictive value of 38%. In the subgroup of patients without comorbid conditions, the specificity increased to 98% and the positive predictive value to 83%, but because only six patients had an abnormal D-dimer level, the 95% confidence interval on the observed positive predictive value is wide (36-100%).

Conclusions: This study demonstrates that the SimpliRED D-dimer assay, which can be performed and interpreted at the bedside within five minutes, has potential clinical utility as an exclusionary test in patients with clinically suspected PE. The assay should be evaluated in large clinical management studies.
Polymorphisms of the Beta Fibrinogen Gene and Plasma Fibrinogen Concentration in Caucasian and Japanese Population Samples
Authors: Iso Hiroyasu , Folsom Aaron R , Winkelmann John C , Koike Kazuko , Harada Shoji , Greenberg Beryl , Sato Shinichi , Shimamoto Takashi , lida Minoru , Komachi Yoshio
Published: July 2018

We reported previously that plasma fibrinogen was significantly higher in U.S. Caucasians than in Japanese, which may contribute to the higher mortality rate of coronary heart disease in the United States than in Japan. To examine the contribution of genetic variations to the race difference in plasma fibrinogen levels, restriction fragment length polymorphisms (RFLPs) of the beta fibrinogen gene were examined in 293 nonsmoking Caucasians and Japanese men and women aged 47-69 years. Three RFLPs were detected by digestion of genomic DNA using the BclI restriction enzyme, polymerase chain reaction (PCR) products using HaeIII and HindIII. The alleles B2 (4.2 kb, BclI digestion), H2 (957 b, HaeIII) and Hd2 (465 b, HindIII) were associated with higher fibrinogen concentrations in previous studies. Because of a strong linkage disequilibrium between HaeIII and HindIII polymorphisms, the data of HindIII was presented. The frequency of the B2 allele was 22% (95% Cl: 17-27%) for Caucasians and 13% (10-17%) for Japanese (the difference: p <0.01). The respective frequency of the Hd2 allele was 26% (21-31%) and 12% (8-16%) (p <0.001). After controlling for age, body mass index, alcohol intake, triglycerides, fish intake, and for women, menopausal status and hormone replacement therapy, the adjusted mean fibrinogen level among Caucasians was 289 mg/dl for genotype B1B1 and 301 mg/dl for genotype B1B2 or B2B2 combined (p = 0.18), and 285 mg/dl for Hd1Hd1 and 306 mg/dl for Hd1Hd2 or Hd2Hd2 combined (p = 0.03). The respective mean values among Japanese were 251 mg/dl for B1B1 and 257 mg/dl for B1B2 or B2B2 combined (p = 0.37), 248 mg/dl for Hd1Hd1 and 259 mg/dl for Hd1Hd2 or Hd2Hd2 combined (p = 0.16). These polymorphisms had a similar effect on plasma fibrinogen concentrations for both men and women. The results suggest that a genetic difference may partly explain the higher plasma fibrinogen in Caucasians than in Japanese.
The Effect of Insulin-Induced Hypoglycaemia on Factor VIII: C Concentrations and Thrombin Activity in Subjects with Type 1 (Insulin-Dependent) Diabetes
Authors: Ibbotson Sally H , Catto Andrew , Davies Andrew , Grant Peter J
Published: July 2018

The effect of insulin-induced hypoglycaemia on plasma coagulant activity was studied in 11 subjects with well-controlled, uncomplicated type 1 diabetes. Thrombin generation was determined in plasma by a computer ex-vivo assisted chromogenic method and by the activated partial thromboplastin time (APTT). In addition, factor VIII :C, thrombin-antithrombin III (TAT) complex and fibrindpeptide A (FPA) levels were measured. Hypoglycaemia induced a rise in mean (SD) factor VIII: C concentrations from a baseline level of 1.13 (0.32) IU/ml to a peak 15 min after onset of symptoms and they remained increased at 90 min [1.54 (0.57) and 1.5 (0.54) IU/ml, p <;0.001 respectively]. A corresponding reduction in time to generate 50% maximal thrombin activity occurred from a pre-insulin value of 56 (6) s to a minimum reading of 46 (7) s at 15 min (p <;0.001) and remained low at 90 min [48 (6) s, p <;0.001]. APTT shortened from 43.3 (4.8) s to 40.1 (4.6) s at 30 min (p <;0.001) but did not fall below the normal range (37.6-42.7 s) and no significant changes in TAT or FPA levels were noted. Factor VIII: C correlated inversely with time to generate 50% maximal thrombin activity and APTT (r = -0.580, p <;0.001; r = -0.673, p <;0.001, n = 66, respectively). The results show that the rise in plasma factor VIII: C levels induced by hypoglycaemia is accompanied by accelerated rates of generation of thrombin in contact-activated plasma, though concentrations of FPA and TAT remain unchanged, although TAT complexes are not a sensitive marker of in vivo thrombin generation.
Glycoprotein Ib Can Mediate Endothelial Cell Attachment to a von Willebrand Factor Substratum
Authors: Beacham Dorothy A , Cruz Miguel A , Handin Robert I
Published: July 2018

Introduction of single amino acid substitutions into the C-terminal Arg-Gly-Asp-Ser (RGDS) site of von Willebrand Factor, referred to as RGD mutant vWF, selectively abrogated vWF binding to platelet glycoprotein IIb/IIIa (GpIIb/IIIa, αIIbβ3 and abolished human umbilical vein endothelial cell (HUVEC) spreading, but not attachment, to RGD mutant vWF (Beacham, D. A., Wise, R. J., Turci, S. M. and Handin, R. I. 1992. J. Biol. Chem. 167, 3409-3415). These results suggested that in addition to the vitronectin receptor (VNR, αvβ3), a second endothelial membrane glycoprotein can mediate HUVEC adhesion to vWF. HUVEC attachment to wild-type (WT) and RGD-mutant vWF was reduced by two proteins known to block the vWF-platelet glycoprotein Ib/IX (GpIb/IX) interaction, the monoclonal antibody AS-7 and the recombinant polypeptide, vWF-A1. The addition of cytochalasin B or DNase I to disrupt potential GPIbα-cytoskeletal interactions enhanced the immunoprecipitation of endothelial GPIbα, caused HUVEC to round up, and increased HUVEC adhesion to RGD mutant vWF. These results indicate that while the VNR is the primary adhesion receptor for vWF, endothelial GPIbα can mediate HUVEC attachment to vWF. GpIb-dependent attachment could contribute to HUVEC adhesion under conditions when cell surface expression of the VNR is downregulated, and VNR-dependent adhesion is reduced.
Factor VII Coagulant Activity in Relation to Serum Lipoproteins and Dietary Fat in Middle-aged Men
Authors: Väisänen Sari , Rankinen Tuomo , Penttilä IIkka , Rauramaa Rainer
Published: July 2018

The associations of serum lipoproteins and habitual diet to factor VII coagulant activity (FVIIc) were analysed in 119 middle-aged men. FVIIc was measured by one-stage clotting assay, cholesterol and triglycerides enzymatically, serum apolipoproteins (apo) immunoturbi- dimetrically and habitual diet using four-day food records. ApoB, cholesterol, triglycerides, apoA-II, LDL cholesterol and dietary fat correlated directly to FVIIc (p <0.001). In multivariate analysis apoB, dietary fat and apoA-II explained 35.3% of the variance in FVIIc. In the lowest apoB tertile FVIIc was increased only when fat intake was high (>38 E%), in the middle tertile FVIIc increased gradually from low to high fat intake, whereas in the highest apoB tertile FVIIc was not related to dietary fat (p = 0.038 for age-adjusted interaction). The present data demonstrate a direct relation between apoB and FVIIc in middle-aged men. Low fat diet seem to associate to decreased FVIIc especially in subjects in the lower end of the apoB distribution.
In Vitro Characterization of High Purity Factor IX Concentrates for the Treatment of Hemophilia B
Authors: Limentani Steven A , Gowell Kerry P , Deitcher Steven R
Published: July 2018

This study employed sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis and immunoblotting to assess the purity of seven high purity factor IX concentrates: Aimafix (Aima), AlphaNine-SD (Alpha Therapeutic), Factor IX VHP (Biotransfusion), Immunine (Immuno), Mononine (Armour Pharmaceutical), Nanotiv (Kabi Pharmacia), and 9MC (Blood Products Laboratory). The mean specific activity of these products ranged from 68 U factor IX/mg (Aimafix) to 246 U factor IX/mg (Mononine). SDS-PAGE analysis showed that the highest purity product, Mononine, had a single contaminating band under non-reducing conditions. Two additional bands were detected when this product was analyzed under reducing conditions. All other products had multiple contaminating bands that were more apparent under reducing than non-reducing conditions. The immunoblot for factor IX showed a dominant factor IX band for all products. In addition, visible light chain of factor IX was detected for AlphaNine-SD, Factor IX VHP, Immunine, Mononine, Nanotiv, and 9MC, suggesting that the factor IX in these products had undergone partial activation to factor IXa. Another contaminating band was visible at 49,500 for all of the products except 9MC. In addition to this band, high molecular weight contaminants were apparent for some products, most notably AlphaNine-SD. The identity of these bands is unknown. Immunoblotting failed to demonstrate factor VII as a contaminant of any of the high purity products, although factor Vila could be detected in some lots of Immunine, Nanotiv, and 9MC by a clot-based assay. Factor X contaminated Aimafix, AlphaNine-SD, Factor IX VHP, Immunine, Nanotiv, and 9MC, but activation products of factor X were not detected. Prothrombin contaminated all of the products except Mononine. Activation products of prothrombin were identified for three of four lots of Immunine and for one lot of Factor IX VHP. These results thus demonstrate that high purity factor IX concentrates differ substantially in the degree to which they are contaminated by potentially thrombogenic materials.
Quantitative and Qualitative Analysis of Platelet GPIb and von Willebrand Factor in Liver Cirrhosis
Authors: Beer J H , Clerici N , Baillod P , von Felten A , Schlappritzi E , Büchi L
Published: July 2018

Numerous abnormalities of plasmatic coagulation and platelet function may contribute to the bleeding in liver cirrhosis with a defective platelet-von Willebrand factor interaction being a potential mechanism. To analyze GPIb and von Willebrand factor in cirrhosis, we quantified the number of GPIb molecules on the platelet surface by flow cytometry, assessed the total (and indirectly the internal) pool of GPIb by ELISA and measured the circulating amount of glycocalicin in plasma as a measure of proteolytic activity and platelet turnover. Von Willebrand factor was characterized by ELISA, by its ristocetin-cofactor activity and by multimer analysis. Botrocetin-induced agglutination was used for functional analysis.

The data from 8 well-characterized cirrhosis patients indicate that total GPIb is insignificantly increased to 46,000 ± 5,000 molecules/P (normal: 39,500 ± 2,000 [SEM]), surface-GPIb is normal with some variability and that the glycocalicin levels are 2-3 times higher than would be expected from the platelet count (= 100 ±5 × 109/1). Von Willebrand factor antigen levels and -activity were 400-500 % of normal with a 22% reduction of the high molecular weight multimers. A significant hyperagglutination response to botrocetin was observed with platelets from both patients and controls using patient plasma as a source of von Willebrand factor. In conclusion, a hyperresponsiveness rather than a defective platelet-von Willebrand factor interaction can be observed in cirrhosis which may compensate for other hemostatic problems and appears to be mediated primarily by increased levels of von Willebrand factor.
Transformation of Cellular Factor XIII into an Active Zymogen Transglutaminase in Thrombin-Stimulated Platelets
Authors: Muszbek László , Haramura Gizella , Polgár János
Published: July 2018

The cellular form of blood coagulation factor XIII (FXIII) is present in platelets, monocytes and macrophages. During long-term stimulation of platelets by thrombin cellular FXIII becomes activated and crosslinks proteins, however, the mechanism of its activation has not been elucidated. It was shown that, contrary to plasma FXIII, the intracellular activation of platelet FXIII does not involve proteolysis. FXIII remained intact in thrombin-activated platelets, i.e., the activation peptide was not removed from the molecule. Part of the zymogen FXIII molecules, however, assumed an active configuration as was demonstrated both by the measurement of transglutaminase activity and by active-site-SH titration. These findings clearly indicate that during platelet activation, when intracellular Ca2+ concentration is raised, a slow non-proteolytic transformation of FXIII zymogen into an active transglutaminase occurs.
Contributions of the lead-bromine weighted bands to the occupied density of states of the hybrid tri-bromide perovskites
Authors: Kirmani A. R. , Mansour A. E. , Saidaminov M. I. , Cui X. , Shi D. , Alofi A. , Losovyj Ya. B. , Gurung G. , Paudel T. R. , Yost A. J. , Dowben P. A. , Tsymbal E. Y. , Amassian A. , Katsiev K.
Published: July 2018

The electronic structure of methylammonium lead bromide (CH3NH3PbBr3) single crystals has been investigated through a combination of resonant photoemission and theoretical modeling. There are Pb spectral contributions throughout the valence band. Importantly, the electronic structure at the top of the valence band is found to be dominated by the hybridized Pb-Br bands, not methylammonium bromide. The results line up with the partial density of states obtained from density functional theory and confirm that much of the valence band has some Pb spectral weight.
A molecular beam apparatus for performing single photon initiated dissociative rearrangement reactions (SPIDRR) with transition metal cation bound organic clusters
Authors: Gutierrez M. G. , Theis Z. , Lewis T. W. R. , Bellert D. J.
Published: July 2018

The study of gas-phase ion-molecule reactions has been influential in the investigation of transition metal mediated bond activation and catalysis. We have furthered this field by developing a new technique capable of measuring the microcanonical kinetics for reactions between transition metal cations and neutral organic molecules. This novel method has been designated as single photon initiated dissociative rearrangement reaction (SPIDRR) technique and provides a nearly direct measurement of microcanonical reaction rate constants. For this reason, SPIDRR offers unique insight into reaction mechanisms and dynamics by assessing the energy dependence of the microcanonical rate constant, as well as measuring product branching fractions and kinetic isotope effects. The following paper provides a detailed overview of SPIDRR and its advantages in the field of gas-phase catalysis research.
Improved accuracy over established temperature-based models of estimating monthly average daily global solar irradiation by using ambient hourly temperature only
Authors: De Souza Keith
Published: July 2018

A recently developed temperature-based model for predicting monthly average hourly global horizontal irradiation has been used to estimate monthly average daily global horizontal irradiation. In addition, a modified form of the Hargreaves-Samani model was implemented. Both models were evaluated alongside five existing temperature-based models due to Hargreaves and Samani, Allen, Bristow and Campbell, Goodin et al., and Hassan et al. for performance and applicability in Trinidad. Calibration and validation of the models were done using datasets of global horizontal irradiation and temperature from 2001–2005 and 2006–2010, respectively. The newly developed temperature-based model performed better than all other models. For an average year, yearly periods, and average and yearly periods collectively, the newly developed temperature-based model yielded root mean square errors of 0.51, 0.86, and 0.68 MJ m−2 day−1, respectively, between the calculated and measured monthly average daily global horizontal irradiation. Similarly, the modified Hargreaves-Samani model was the next best performer with root mean square errors of 0.91, 1.31, and 1.11 MJ m−2 day−1, respectively.
Theoretical study on the polymer translocation into an attractive sphere
Authors: Sun Li-Zhen , Luo Meng-Bo , Cao Wei-Ping , Li Haibin
Published: July 2018

We report a non-sampling model, combining the blob method with the standard lattice-based approximation, to calculate the free energy for the polymer translocation into an attractive sphere (i.e., spherical confined trans side) through a small pore. The translocation time is then calculated by the Fokker-Planck equation based on the free energy profile. There is a competition between the confinement effect of the sphere and the polymer-sphere attraction. The translocation time is increased due to the confinement effect of the sphere, whereas it is reduced by the polymer-sphere attraction. The two effects offset each other at a special polymer-sphere attraction which is dependent on the sphere size, the polymer length, and the driving force. Moreover, the entire translocation process can be divided into an uncrowded stage where the polymer does not experience the confinement effect of the sphere and a crowded stage where the polymer is confined by the sphere. At the critical sphere radius, the durations of the two (uncrowded and crowded) stages are the same. The critical sphere radius R* has a scaling relation with the polymer length N as R* ∼ Nβ. The calculation results show that the current model can effectively treat the translocation of a three-dimensional self-avoiding polymer into the spherical confined trans side.
Analysis of fluctuations in the first return times of random walks on regular branched networks
Authors: Peng Junhao , Xu Guoai , Shao Renxiang , Chen Lin , Stanley H. Eugene
Published: July 2018

The first return time (FRT) is the time it takes a random walker to first return to its original site, and the global first passage time (GFPT) is the first passage time for a random walker to move from a randomly selected site to a given site. We find that in finite networks, the variance of FRT, Var(FRT), can be expressed as Var(FRT) = 2⟨FRT⟩⟨GFPT⟩ − ⟨FRT⟩2 − ⟨FRT⟩, where ⟨·⟩ is the mean of the random variable. Therefore a method of calculating the variance of FRT on general finite networks is presented. We then calculate Var(FRT) and analyze the fluctuation of FRT on regular branched networks (i.e., Cayley tree) by using Var(FRT) and its variant as the metric. We find that the results differ from those in such other networks as Sierpinski gaskets, Vicsek fractals, T-graphs, pseudofractal scale-free webs, (u, v) flowers, and fractal and non-fractal scale-free trees.
Precipitation strengthening in Cu–Ni–Si alloys modeled with ab initio based interatomic potentials
Authors: Hocker Stephen , Lipp Hansjörg , Eisfeld Eugen , Schmauder Siegfried , Roth Johannes
Published: July 2018

Effective interaction potentials suitable for Cu/δ–Ni2Si and Cu/β–Ni3Si are developed. We optimise the potential parameters of an embedded atom method potential to reproduce forces, energies, and stresses obtained from ab initio calculations. Details of the potential generation are given, and its validation is demonstrated. The potentials are used in molecular dynamics simulations of shear tests to study the interactions of edge dislocations with coherent δ–Ni2Si and β–Ni3Si precipitates embedded in a copper matrix. In spite of significantly different crystallographic structures of copper and δ–Ni2Si which usually result in circumvention of dislocations, we also observed cutting processes in our simulations. Dislocations cut for a specific orientation of the δ–Ni2Si precipitate and in some cases where dislocation loops originating from previous circumvention processes are present in the glide plane. It is found that β–Ni3Si precipitates have a similar effect on precipitation strengthening as δ–Ni2Si. Dislocations usually cut β–Ni3Si but increased coherency strain can lead to circumvention processes.
Evidence for a surface anomaly during the cubic-tetragonal phase transition in BaTiO3(001)
Authors: Barrett N. , Dionot J. , Martinotti D. , Salje E. K. H. , Mathieu C.
Published: July 2018

We have used low energy electron microscopy (LEEM) to study the evolution of the surface structure of BaTiO3(001) during the ferroelectric-paraelectric phase transition (120 °C, P4mm-Pm3m). Transient surface structures appear under heating at temperatures slightly above TC. Intersections between polar domain walls and the sample surface persist in the surface layer at 126.0 °C while the bulk has already transformed into the cubic phase. The wall signals are criss-crossed by a second set of stripe patterns with roughly perpendicular orientation at 126.3 °C. These surface patterns coarsen under further heating to 126.9 °C. The LEEM image is dominated in the ferroelectric state by intersections of ferroelastic/ferroelectric 90° walls and the surface. The intersection lines are charged.
Electrical properties of extended defects in strain relaxed GeSn
Authors: Gupta Somya , Simoen Eddy , Loo Roger , Shimura Yosuke , Porret Clement , Gencarelli Federica , Paredis Kristof , Bender Hugo , Lauwaert Johan , Vrielinck Henk , Heyns Marc
Published: July 2018

We report the electrical properties of 60° dislocations originating from the +1.2% lattice mismatch between an unintentionally doped, 315 nm thick Ge0.922Sn0.078 layer (58% relaxed) and the underlying Ge substrate, using deep level transient spectroscopy. The 60° dislocations are found to be split into Shockley partials, binding a stacking fault. The dislocations exhibit a band-like distribution of electronic states in the bandgap, with the highest occupied defect state at ∼EV + 0.15 eV, indicating no interaction with point defects in the dislocation's strain field. A small capture cross-section of 1.5 × 10−19 cm2 with a capture barrier of 60 meV is observed, indicating a donor-like nature of the defect-states. Thus, these dislocation-states are not the source of unintentional p-type doping in the Ge0.922Sn0.078 layer. Importantly, we show that the resolved 60° dislocation-states act as a source of leakage current by thermally generating minority electrons via the Shockley-Read-Hall mechanism.
Synthetic diagnostic for assessing spatial averaging of charge exchange recombination spectroscopy measurements
Authors: Chrystal C. , Sulyman A. A. , Haskey S. R. , Burrell K. H. , Grierson B. A.
Published: July 2018

A synthetic charge exchange recombination spectroscopy diagnostic based on the FIDASIM modeling suite has been created for the DIII-D tokamak. This synthetic diagnostic assumes that the ions have Maxwellian distribution functions on each flux surface and models emission from charge exchange events between the beam neutrals and a fully ionized impurity. This work was motivated by the observation of non-Gaussian spectra that may be caused by spatial averaging, atomic physics, or non-Maxwellian distribution functions. Measurements of non-Gaussian spectra commonly observed in the high confinement mode pedestal and in plasmas with large core gradients are compared to the synthetic diagnostic. Spatial averaging alone cannot account for the observations in these two cases, opening up the possibility of there being other causes such as non-Maxwellian distribution functions. The synthetic diagnostic has also been used to resolve a long-standing issue: it is shown that the lower temperatures measured by using vertical view chords relative to tangential view chords are due to increased spatial averaging for vertical views due to the DIII-D neutral beams being approximately twice as tall as they are wide.
Terahertz magnon and crystal-field transition manipulated by R3+-Fe3+ interaction in Sm0.5Pr0.5FeO3
Authors: Liu Xiumei , Xie Tao , Guo Jiajia , Yang Senmiao , Song Yuna , Lin Xian , Cao Shixun , Cheng Zhenxiang , Jin Zuanming , Wu Anhua , Ma Guohong , Yao Jianquan
Published: July 2018

We use terahertz (THz) magnetic and electric fields to investigate the magnetic and optoelectronic responses of the Sm0.5Pr0.5FeO3 (SPFO) crystal, respectively, by THz time-domain spectroscopy. It is found that the spin reorientation transition (SRT) in SPFO occurs in the temperature range of 175–210 K. The SRT is not observed in PrFeO3. The quasi-antiferromagnetic magnon frequency has a blue-shift from 0.42 THz (PrFeO3) to 0.46 THz (SPFO) at room temperature, due to the enhanced anisotropy constant. The refractive index of SPFO in the THz frequency decreases around 3% compared with that of the PrFeO3 crystal. In addition, it can be found that the energy scale of crystal-field transitions has a red-shift for the doped single crystal. We expect our results to make rare-earth orthoferrites accessible to potential applications in THz spintronic devices.
Transmitting-absorbing material based on resistive metasurface
Authors: Meng Fan-Guang , Li Hao , Fan Di-Gang , Li Fei-Fei , Xue Feng-Zhi , Chen Ping , Wu Rui-Xin
Published: July 2018

We theoretically and experimentally studied a transmitting-absorbing material that had transmission window within the absorption band. The material had a sandwich structure comprised of a resistive metasurface, a dielectric substrate and a metallic slot frequency-selective surface (FSS). The material showed lower reflectivity in a wide frequency range; the -10 dB absorbing bandwidth could be over 76% (64% in experiments). Meanwhile in the middle of the range the transmittance up to -1.7 dB was observed at about 10 GHz where slot FSS had good transparency. We showed the lower reflectivity of our material was mainly due to the absorption of incident radiation energy except for the transparent window where the radiation energy passed through the materials. The transmitting window could be adjusted by changing the geometry parameters of slot FSS. Our material had the advantages of thin thickness, small size of unit cell, convenient fabrication and easy to extend to other frequency bands. This kind of transmitting-absorbing material provided a new way for the applications, such as light harvesting, sensing and radome materials.
Contact electrification efficiency dependence on surface energy at the water-solid interface
Authors: Shahzad Amir , Wijewardhana K. Rohana , Song Jang-Kun
Published: July 2018

Liquid-solid contact electrification is a useful mechanism to harvest wasted micromechanical energy. In this study, we investigate how the surface properties of a solid substrate affect contact electrification efficiency. Substrate surfaces were modified from hydrophilic to hydrophobic by changing the density of self-assembled monolayers (SAMs) on a SiO2 surface. A substrate with a partially-covered SAM exhibited superior performance. The partially-covered SAM substrate is hydrophobic enough to induce quick dewetting of water from the surface and sufficiently electronegative to induce a high charge density on the surface. The quick dewetting results from the aliphatic tail groups of the SAM and -OH groups make the SiO2 surface electronegative; these two competing properties can be simultaneously obtained by optimizing the SAM density. Our findings contribute to the understanding of contact electrification in liquid-solid-type energy-harvesting devices and advance the strategies to maximize the electrification efficiency by optimizing surface geometries and properties.
Photogeneration and interactive reactions of three reactive species in the Seto Inland Sea, Japan
Authors: Adesina Adeniyi Olufemi , Anifowose Adebanjo Jacob , Takeda Kazuhiko , Sakugawa Hiroshi
Published: July 2018

Environmental contextPhotogenerated reactive species play important roles in the degradation of dissolved organic pollutants. Photogeneration and concerted measurements of hydroxyl (·OH), nitric oxide (NO·) and superoxide (O2·−) radicals in samples from the Seto Inland Sea suggest that their interactive reactions could yield peroxynitrite (ONOO−), a secondary reactive species. These results reveal how discrete photochemical reactions synergise to influence the variety and fates of reactive species in a marine environment.
AbstractPhotochemically generated reactive species are involved in photodegradation of dissolved organic pollutants in natural waters. However, there is a dearth of empirical evidence, from each batch of water samples collected, to predict the influence of interactive reactions among several photogenerated reactive species on their variety and fates in natural waters. Concerted photogeneration and measurement of hydroxyl (·OH), nitric oxide (NO·) and superoxide (O2·−) radicals were carried out on water samples obtained during two consecutive summers in 2016 and 2017 from the Seto Inland Sea, Japan. Photogeneration rates of ·OH are (6.98–35.27) × 10−12 M s−1, and those of NO· are (1.20–58.25) × 10−12 M s−1. Compared with these generation rates, that for O2·− ((4.54–18.20) × 10−10 M s−1) was the highest, which suggests that O2·− is a very important photochemically generated reactive species in coastal seawater. The average steady-state concentrations of the three reactive species are ·OH, 7.23 × 10−18 M; O2·−, 3.79 × 10−12 M; and NO·, 1.39 × 10−10 M. Estimated mutual consumption or sink percentages via interactive reactions between O2·− and NO· radicals are five to nine orders of magnitude higher than any other radical pair considered in this study. Hence, we predict that the reaction between photochemical O2·− and NO· could dominate to form ONOO−, a powerful oxidant and nitrating agent, in the coastal marine environment.
Extent, regional distribution and changes in area of different classes of wetland
Authors: Davidson Nick C. , Finlayson C. Max
Published: July 2018

We compiled available data and information on the global and regional areas (Ramsar regions), and changes in area, of 22 classes of marine or coastal and inland wetlands. From those classes for which there is information, inland natural surface wetlands (forming ~77% of total surface wetland extent) are dominated by non-forested peatlands, marshes and swamps on alluvial soils, with peatlands forming ~33% of natural inland wetlands. The smaller area of marine or coastal wetlands (~10% of total wetland extent) is dominated by unvegetated tidal flats and saltmarshes. Largest areas of human-made wetlands for which there is information are rice paddy and water storage bodies, with a much smaller area of tropical oil palm and pulpwood plantations. These human-made wetlands are all increasing in area. The reported decline in global natural wetland area is occurring across almost all classes of inland and marine or coastal natural wetlands. Total global wetland area estimated from these wetland classes is between 15.2×106 and 16.2×106km2, similar to recent global wetland area estimates derived from remote sensing. Given the considerable data gaps for area of wetland classes, even the most recent other estimates of global wetland extent are likely to be underestimates.
Different roles of myocardial ROCK1 and ROCK2 in cardiac dysfunction and postcapillary pulmonary hypertension in mice
Authors: Sunamura Shinichiro , Satoh Kimio , Kurosawa Ryo , Ohtsuki Tomohiro , Kikuchi Nobuhiro , Elias-Al-Mamun Md. , Shimizu Toru , Ikeda Shohei , Suzuki Kota , Satoh Taijyu , Omura Junichi , Nogi Masamichi , Numano Kazuhiko , Siddique Mohammad Abdul Hai , Miyata Satoshi , Miura Masahito , Shimokawa Hiroaki
Published: July 2018

Significance

Our data suggest opposite roles for ROCK1 and ROCK2 in cardiomyocytes. Additional studies identified downstream targets of ROCK1 and ROCK2 related to calcium handling, mitochondrial function, and oxidative stress. In particular, our findings indicate that cyclophilin A (CyPA) and basigin (Bsg), both of which augment oxidative stress, enhanced cardiac dysfunction and postcapillary pulmonary hypertension (PH) in
cROCK1
−/−
mice, while their expressions were lower in
cROCK2
−/−
mice. Finally, screening of the public chemical library in the Drug Discovery Initiative enabled us to identify compounds that reduce the expressions of CyPA and Bsg. Among them, celastrol suppressed the expression of both CyPA and Bsg in heart and lungs, thereby ameliorating both heart failure and postcapillary PH in mice.
Virion structure and genome delivery mechanism of sacbrood honeybee virus
Authors: Procházková Michaela , Füzik Tibor , Škubník Karel , Moravcová Jana , Ubiparip Zorica , Přidal Antonín , Plevka Pavel
Published: July 2018

Significance

Honey bee pollination is required to sustain the biodiversity of wild flora and for agricultural production; however, honey bee populations in Europe and North America are declining due to virus infections. Sacbrood virus (SBV) infection is lethal to honey bee larvae and decreases the fitness of honey bee colonies. Here we present the structure of the SBV particle and show that it contains 60 copies of a minor capsid protein attached to its surface. No similar minor capsid proteins have been previously observed in any of the related viruses. We also present a structural analysis of the genome release of SBV. The possibility of blocking virus genome delivery may provide a tool to prevent the spread of this honey bee pathogen.
Diffusion in networks and the virtue of burstiness
Authors: Akbarpour Mohammad , Jackson Matthew O.
Published: July 2018

Significance

The contagion of disease and the diffusion of information depend on personal contact. People are not always available to interact with those around them, and the timing of people’s activities determines whether people have opportunities to meet and transmit a germ, idea, etc., and ultimately whether widespread contagion or diffusion occurs. We show that, in a simple model of contagion or diffusion, the greatest levels of spreading occur when there is heterogeneity in activity patterns: Some people are active for long periods of time and then inactive for long periods, changing their availability only infrequently, while other people alternate frequently between being active and inactive. This observation has policy implications for limiting contagious diseases as well as promoting diffusion of information.
NADPH oxidase-generated reactive oxygen species in mature follicles are essential for
Drosophila
ovulation
Authors: Li Wei , Young Jessica F. , Sun Jianjun
Published: July 2018

Significance

Reactive oxygen species (ROS) cause oxidative stress and damage in many pathological conditions, but they can also function as signaling molecules in physiological processes. It is difficult, however, to decipher where ROS come from and which ROS are involved in these processes. In this article, we demonstrate that a NADPH oxidase (NOX) and an extracellular superoxide dismutase (SOD3) function in follicle cells of
Drosophila
egg chambers to produce hydrogen peroxide, which regulates follicle rupture and ovulation, a process essential for reproduction. NOX and SOD3 are expressed in human follicles and could potentially play similar roles in humans. Our work thus provides potential targets for treating ROS-related infertility or developing novel contraceptive approaches.
N6-Furfuryladenine is protective in Huntington’s disease models by signaling huntingtin phosphorylation
Authors: Bowie Laura E. , Maiuri Tamara , Alpaugh Melanie , Gabriel Michelle , Arbez Nicolas , Galleguillos Danny , Hung Claudia L. K. , Patel Shreya , Xia Jianrun , Hertz Nicholas T. , Ross Christopher A. , Litchfield David W. , Sipione Simonetta , Truant Ray
Published: July 2018

Significance

We have discovered a molecule derived from DNA-damage repair that can correct the lack of phosphorylation of mutant huntingtin, the cause of Huntington’s disease (HD). In a mouse model, treatment reverses HD-like disease, and we see the lowering of mutant huntingtin levels to normal. The mechanism of this molecule is that it is processed to make a signal for kinase activity essential for repairing DNA. This mechanism is critical when neurons are stressed and have very low or absent energy levels. We propose that this molecule is a type of signaling from DNA-damage repair that occurs at dangerously low ATP levels.