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1.
ACS Nano ; 16(10): 17336-17346, 2022 Oct 25.
Article in English | MEDLINE | ID: mdl-36126321

ABSTRACT

In transport, the topological Hall effect (THE) presents itself as nonmonotonic features (or humps and dips) in the Hall signal and is widely interpreted as a sign of chiral spin textures, like magnetic skyrmions. However, when the anomalous Hall effect (AHE) is also present, the coexistence of two AHEs could give rise to similar artifacts, making it difficult to distinguish between genuine THE with AHE and two-component AHE. Here, we confirm genuine THE with AHE by means of transport and magneto-optical Kerr effect (MOKE) microscopy, in which magnetic skyrmions are directly observed, and find that genuine THE occurs in the transition region of the AHE. In sharp contrast, the artifact "THE" or two-component AHE occurs well beyond the saturation of the "AHE component" (under the false assumption of THE + AHE). Furthermore, we distinguish artifact "THE" from genuine THE by three methods: (1) minor loops, (2) temperature dependence, and (3) gate dependence. Minor loops of genuine THE with AHE are always within the full loop, while minor loops of the artifact "THE" may reveal a single loop that cannot fit into the "AHE component". In addition, the temperature or gate dependence of the artifact "THE" may also be accompanied by a polarity change of the "AHE component", as the nonmonotonic features vanish, while the temperature dependence of genuine THE with AHE reveals no such change. Our work may help future researchers to exercise caution and use these methods for careful examination in order to ascertain the genuine THE.

2.
J Immunol ; 208(12): 2726-2737, 2022 06 15.
Article in English | MEDLINE | ID: mdl-35688465

ABSTRACT

SM03, an anti-CD22 recombinant IgG1 mAb, is currently in a phase III clinical trial for the treatment of rheumatoid arthritis (NCT04312815). SM03 showed good safety and efficacy in phase I systemic lupus erythematosus and phase II moderate to severe rheumatoid arthritis clinical trials. We propose the success of SM03 as a therapeutic to systemic autoimmune diseases is through the utilization of a novel mechanism of action unique to SM03. CD22, an inhibitory coreceptor of the BCR, is a potential immunotherapeutic target against autoimmune diseases. SM03 could disturb the CD22 homomultimeric configuration through disrupting cis binding to α2,6-linked sialic acids, induce rapid internalization of CD22 from the cell surface of human B cells, and facilitate trans binding between CD22 to human autologous cells. This in turn increased the activity of the downstream immunomodulatory molecule Src homology region 2 domain-containing phosphatase 1 (SHP-1) and decreased BCR-induced NF-κB activation in human B cells and B cell proliferation. This mechanism of action gives rationale to support the significant amelioration of disease and good safety profile in clinical trials, as by enabling the "self" recognition mechanism of CD22 via trans binding to α2,6 sialic acid ligands on autologous cells, SM03 specifically restores immune tolerance of B cells to host tissues without affecting the normal B cell immune response to pathogens.


Subject(s)
Arthritis, Rheumatoid , Lupus Erythematosus, Systemic , Arthritis, Rheumatoid/therapy , Humans , Ligands , N-Acetylneuraminic Acid , Polysaccharides , Receptors, Antigen, B-Cell , Sialic Acid Binding Ig-like Lectin 2 , Sialic Acids
3.
ACS Appl Mater Interfaces ; 11(42): 39369-39375, 2019 Oct 23.
Article in English | MEDLINE | ID: mdl-31603641

ABSTRACT

Current-induced spin-orbit torques (SOTs) enable efficient electrical manipulation of the magnetization in heterostructures with a perpendicular magnetic anisotropy through the Rashba effect or spin-Hall effect. However, in conventional SOT-based heterostructures, an in-plane bias magnetic field along the current direction is required for the deterministic switching. Here, we report that the field-free SOT switching can be achieved by introducing a wedged oxide interface between a heavy metal and a ferromagnet. The results demonstrate that the field-free SOT switching is determined by a current-induced perpendicular effective field (Hzeff) originating from the interfacial Rashba effect due to the lateral structural symmetry-breaking introduced by the wedged oxide layer. Furthermore, we show that the sign and magnitude of Hzeff exhibit a significant dependence on the interfacial oxygen content, which can be controlled by the inserted oxide thickness. Our findings provide a deeper insight into the field-free SOT switching by the interfacial Rashba effect.

4.
Article in Russian | MEDLINE | ID: mdl-31156228

ABSTRACT

The relevance of the problem is determined by the growth of elderly population in the world and in Russia and by the increase in the frequency of non-psychotic mental disorders (non-PMD) in the structure of psychiatric diseases. The authors consider the current state of research in the field of non-PMD of old age, including neurotic disorders (ND). An analysis of the literature has shown that there is no convergent view on the ND of old age. As a consequence, there are contradictory views from researchers or psychiatric schools on the ND prevalence and morbidity. Attention is drawn to the insufficient diagnosis of non-PMD in the primary link of health care, difficulties of distinguishing ND from neurotic-like states, necessity in the clarification of the epidemiology of neuroses and efficiency of psychotherapeutic help. The use of resources of able-bodied people is important for the socio-economic development of the country.


Subject(s)
Mental Disorders , Neurotic Disorders , Aged , Humans , Mental Disorders/diagnosis , Mental Disorders/drug therapy , Mental Disorders/epidemiology , Neurotic Disorders/diagnosis , Neurotic Disorders/drug therapy , Neurotic Disorders/epidemiology , Prevalence , Psychotropic Drugs/therapeutic use , Russia/epidemiology
5.
Am J Pathol ; 188(7): 1597-1607, 2018 07.
Article in English | MEDLINE | ID: mdl-29630856

ABSTRACT

Epithelial-to-mesenchymal transition (EMT) is postulated to be a prerequisite for the establishment of endometriosis (EMS), a common reproductive disorder in women. Our previous studies have demonstrated the elevated expression of transmembrane glycoprotein CD147 and its prosurvival effect on abnormal cells in endometriosis. Intriguingly, CD147 is known to promote EMT in cancers. However, the involvement of CD147 in EMT during the establishment of endometriosis remains incompletely understood. We found that CD147 promotes EMT in human endometrial adenocarcinoma cell line Ishikawa. We identified a novel CD147-interacting partner, cellular apoptosis susceptibility protein (CAS), which stabilized the interaction between E-cadherin (E-cad) and ß-catenin (ß-cat) by forming the CAS/E-cad/ß-cat complex. Down-regulation of CAS led to the release and nuclear translocation of ß-cat from E-cad, resulting in the overexpression of the EMT-promoting gene SNAIL. Interestingly, overexpression of CD147 impaired the interaction between CAS and E-cad and triggered the release of ß-cat from the CAS/E-cad/ß-cat complex, which in turn led to EMT. Furthermore, CAS was down-regulated in EMS, with elevated levels of CD147 and nuclear ß-cat. These findings suggest a previously undefined role of CAS in regulating EMT and reveal the involvement of a CD147-induced EMT signaling pathway in pathogenic progression of EMS.


Subject(s)
Antigens, CD/metabolism , Basigin/metabolism , Cadherins/metabolism , Cellular Apoptosis Susceptibility Protein/metabolism , Endometrial Neoplasms/pathology , Endometriosis/pathology , Epithelial-Mesenchymal Transition , beta Catenin/metabolism , Adenocarcinoma/genetics , Adenocarcinoma/metabolism , Adenocarcinoma/pathology , Adult , Antigens, CD/genetics , Basigin/genetics , Cadherins/genetics , Case-Control Studies , Cell Membrane , Cellular Apoptosis Susceptibility Protein/genetics , Endometrial Neoplasms/genetics , Endometrial Neoplasms/metabolism , Endometriosis/genetics , Endometriosis/metabolism , Female , Gene Expression Regulation, Neoplastic , Humans , Middle Aged , Protein Interaction Domains and Motifs , Signal Transduction , Tumor Cells, Cultured , beta Catenin/genetics
6.
J Phys Condens Matter ; 30(22): 225301, 2018 Jun 06.
Article in English | MEDLINE | ID: mdl-29658884

ABSTRACT

In this study, unique thermal transport features of nanowires over bulk materials are investigated using a combined analysis based on lattice dynamics and equilibrium molecular dynamics (EMD). The evaluation of the thermal conductivity (TC) of Lenard-Jones nanowires becomes feasible due to the multi-step normal mode decomposition (NMD) procedure implemented in the study. A convergence issue of the TC of nanowires is addressed by the NMD implementation for two case studies, which employ pristine nanowires (PNW) and superlattice nanowires. Interestingly, mode relaxation times at low frequencies of acoustic branches exhibit signs of approaching constant values, thus indicating the convergence of TC. The TC evaluation procedure is further verified by implementing EMD-based Green-Kubo analysis, which is based on a fundamentally different physical perspective. Having verified the NMD procedure, the non-monotonic trend of the TC of nanowires is addressed. It is shown that the principal cause for the observed trend is due to the competing effects of long wavelength phonons and phonon-surface scatterings as the nanowire's cross-sectional width is changed. A computational procedure is developed to decompose the different modal contribution to the TC of shell alloy nanowires (SANWs) using virtual crystal NMD and the Allen-Feldman theory. Several important conclusions can be drawn from the results. A propagons to non-propagons boundary appeared, resulting in a cut-off frequency (ω cut); moreover, as alloy atomic mass is increased, ω cut shifts to lower frequencies. The existence of non-propagons partly causes the low TC of SANWs. It can be seen that modes with low frequencies demonstrate a similar behavior to corresponding modes of PNWs. Moreover, lower group velocities associated with higher alloy atomic mass resulted in a lower TC of SANWs.

7.
J Soc Psychol ; 158(1): 7-22, 2018.
Article in English | MEDLINE | ID: mdl-28375810

ABSTRACT

Tattoos are increasing in popularity, yet minimal research has examined implicit attitudes or the relationship between implicit and explicit attitudes toward tattooed individuals. Seventy-seven online participants (Mage = 36.09, 52% women, 78% white, 26% tattooed) completed measures assessing implicit and explicit attitudes toward tattooed individuals. Results revealed evidence of negative implicit attitudes, which were associated with less perceived warmth, competence, and negative explicit evaluations. However, implicit attitudes were not correlated with measures of disgust or social distance. In addition, age predicted implicit prejudice, but other individual difference measures-such as personal tattoo possession, political identity, and internal/external motivations to respond without prejudice-did not. These findings are discussed in terms of how attitudes toward tattooed individuals may be multifaceted, and research may benefit from measuring implicit and explicit attitudes.


Subject(s)
Attitude , Prejudice , Social Perception , Tattooing , Adult , Female , Humans , Male
8.
Sci Rep ; 6: 23956, 2016 Apr 06.
Article in English | MEDLINE | ID: mdl-27050160

ABSTRACT

Current-induced spin-orbit torques (SOTs) in structurally asymmetric multilayers have been used to efficiently manipulate magnetization. In a structure with vertical symmetry breaking, a damping-like SOT can deterministically switch a perpendicular magnet, provided an in-plane magnetic field is applied. Recently, it has been further demonstrated that the in-plane magnetic field can be eliminated by introducing a new type of perpendicular field-like SOT via incorporating a lateral structural asymmetry into the device. Typically, however, when a current is applied to such devices with combined vertical and lateral asymmetries, both the perpendicular field-like torque and the damping-like torque coexist, hence jointly affecting the magnetization switching behavior. Here, we study perpendicular magnetization switching driven by the combination of the perpendicular field-like and the damping-like SOTs, which exhibits deterministic switching mediated through domain wall propagation. It is demonstrated that the role of the damping-like SOT in the deterministic switching is highly dependent on the magnetization direction in the domain wall. By contrast, the perpendicular field-like SOT is solely determined by the relative orientation between the lateral structural asymmetry and the current direction, regardless of the magnetization direction in the domain wall. The experimental results further the understanding of SOTs-induced switching, with implications for spintronic devices.

9.
Nano Lett ; 16(3): 1981-8, 2016 Mar 09.
Article in English | MEDLINE | ID: mdl-26848783

ABSTRACT

Magnetic skyrmions, which are topologically protected spin textures, are promising candidates for ultralow-energy and ultrahigh-density magnetic data storage and computing applications. To date, most experiments on skyrmions have been carried out at low temperatures. The choice of available materials is limited, and there is a lack of electrical means to control skyrmions in devices. In this work, we demonstrate a new method for creating a stable skyrmion bubble phase in the CoFeB-MgO material system at room temperature, by engineering the interfacial perpendicular magnetic anisotropy of the ferromagnetic layer. Importantly, we also demonstrate that artificially engineered symmetry breaking gives rise to a force acting on the skyrmions, in addition to the current-induced spin-orbit torque, which can be used to drive their motion. This room-temperature creation and manipulation of skyrmions offers new possibilities to engineer skyrmionic devices. The results bring skyrmionic memory and logic concepts closer to realization in industrially relevant and manufacturable thin film material systems.

10.
Nat Nanotechnol ; 11(4): 352-9, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26727198

ABSTRACT

Electric-field manipulation of magnetic order has proved of both fundamental and technological importance in spintronic devices. So far, electric-field control of ferromagnetism, magnetization and magnetic anisotropy has been explored in various magnetic materials, but the efficient electric-field control of spin-orbit torque (SOT) still remains elusive. Here, we report the effective electric-field control of a giant SOT in a Cr-doped topological insulator (TI) thin film using a top-gate field-effect transistor structure. The SOT strength can be modulated by a factor of four within the accessible gate voltage range, and it shows strong correlation with the spin-polarized surface current in the film. Furthermore, we demonstrate the magnetization switching by scanning gate voltage with constant current and in-plane magnetic field applied in the film. The effective electric-field control of SOT and the giant spin-torque efficiency in Cr-doped TI may lead to the development of energy-efficient gate-controlled spin-torque devices compatible with modern field-effect semiconductor technologies.

11.
Nat Commun ; 6: 8958, 2015 Dec 08.
Article in English | MEDLINE | ID: mdl-26643048

ABSTRACT

Manipulating magnetism by electric current is of great interest for both fundamental and technological reasons. Much effort has been dedicated to spin-orbit torques (SOTs) in metallic structures, while quantitative investigation of analogous phenomena in magnetic insulators remains challenging due to their low electrical conductivity. Here we address this challenge by exploiting the interaction of light with magnetic order, to directly measure SOTs in both metallic and insulating structures. The equivalency of optical and transport measurements is established by investigating a heavy-metal/ferromagnetic-metal device (Ta/CoFeB/MgO). Subsequently, SOTs are measured optically in the contrasting case of a magnetic-insulator/heavy-metal (YIG/Pt) heterostructure, where analogous transport measurements are not viable. We observe a large anti-damping torque in the YIG/Pt system, revealing its promise for spintronic device applications. Moreover, our results demonstrate that SOT physics is directly accessible by optical means in a range of materials, where transport measurements may not be possible.

12.
Kardiologiia ; 55(2): 16-20, 2015.
Article in Russian | MEDLINE | ID: mdl-26164983

ABSTRACT

Aim of this study was to assess incidence and severity of acute kidney injury (AKI) in patients with ST-elevation (STE) myocardial infarction (MI) after thrombolytic therapy with alteplase or streptokinase. Among 292 included patients (227 men, 65 women, mean age 58 ± 11 years) 170 received streptokinase, 122 - alteplase. Coronary angiography in acute stage of MI was an exclusion criterion. Thrombolysis was effective in 213 (73%) patients. There was no statistically significant difference in effectiveness of thrombolysis among streptokinase or alteplase treated patients. Incidence of AKI in patients with STEMI was 25%. Both incidence and severity of AKI were higher in streptokinase treated patients. Only stage II-III AKI was significantly associated with higher in-hospital mortality.


Subject(s)
Acute Kidney Injury/epidemiology , Fibrinolytic Agents/therapeutic use , Myocardial Infarction/drug therapy , Thrombolytic Therapy/methods , Acute Kidney Injury/etiology , Coronary Angiography , Electrocardiography , Female , Follow-Up Studies , Hospital Mortality/trends , Humans , Incidence , Male , Middle Aged , Myocardial Infarction/diagnosis , Myocardial Infarction/mortality , Retrospective Studies , Russia/epidemiology , Survival Rate/trends
13.
J Diabetes Sci Technol ; 8(6): 1157-67, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25097056

ABSTRACT

In this work, we used a sensitive and noninvasive computational method to assess diabetic cardiovascular autonomic neuropathy (DCAN) from pulse oximeter (photoplethysmographic; PPG) recordings from mice. The method, which could be easily applied to humans, is based on principal dynamic mode (PDM) analysis of heart rate variability (HRV). Unlike the power spectral density, PDM has been shown to be able to separately identify the activities of the parasympathetic and sympathetic nervous systems without pharmacological intervention. HRV parameters were measured by processing PPG signals from conscious 1.5- to 5-month-old C57/BL6 control mice and in Akita mice, a model of insulin-dependent type 1 diabetes, and compared with the gold-standard Western blot and immunohistochemical analyses. The PDM results indicate significant cardiac autonomic impairment in the diabetic mice in comparison to the controls. When tail-cuff PPG recordings were collected and analyzed starting from 1.5 months of age in both C57/Bl6 controls and Akita mice, onset of DCAN was seen at 3 months in the Akita mice, which persisted up to the termination of the recording at 5 months. Western blot and immunohistochemical analyses also showed a reduction in nerve density in Akita mice at 3 and 4 months as compared to the control mice, thus, corroborating our PDM data analysis of HRV records. Western blot analysis of autonomic nerve proteins corroborated the PPG-based HRV analysis via the PDM approach. In contrast, traditional HRV analysis (based on either the power spectral density or time-domain measures) failed to detect the nerve rarefaction.


Subject(s)
Autonomic Nervous System Diseases/diagnosis , Diabetes Mellitus, Experimental/complications , Diabetic Neuropathies/diagnosis , Heart Rate/physiology , Oximetry/methods , Animals , Autonomic Nervous System Diseases/etiology , Blotting, Western , Heart/innervation , Immunohistochemistry , Mice , Mice, Inbred C57BL
14.
Nat Nanotechnol ; 9(7): 548-54, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24813694

ABSTRACT

Magnetization switching by current-induced spin-orbit torques is of great interest due to its potential applications in ultralow-power memory and logic devices. The switching of ferromagnets with perpendicular magnetization is of particular technological relevance. However, in such materials, the presence of an in-plane external magnetic field is typically required to assist spin-orbit torque-driven switching and this is an obstacle for practical applications. Here, we report the switching of out-of-plane magnetized Ta/Co(20)Fe(60)B(20)/TaO(x) structures by spin-orbit torques driven by in-plane currents, without the need for any external magnetic fields. This is achieved by introducing a lateral structural asymmetry into our devices, which gives rise to a new field-like spin-orbit torque when in-plane current flows in these structures. The direction of the current-induced effective field corresponding to this field-like spin-orbit torque is out-of-plane, facilitating the switching of perpendicular magnets.

15.
Nano Lett ; 14(6): 3459-65, 2014 Jun 11.
Article in English | MEDLINE | ID: mdl-24844837

ABSTRACT

Introducing magnetic order in a topological insulator (TI) breaks time-reversal symmetry of the surface states and can thus yield a variety of interesting physics and promises for novel spintronic devices. To date, however, magnetic effects in TIs have been demonstrated only at temperatures far below those needed for practical applications. In this work, we study the magnetic properties of Bi2Se3 surface states (SS) in the proximity of a high Tc ferrimagnetic insulator (FMI), yttrium iron garnet (YIG or Y3Fe5O12). Proximity-induced butterfly and square-shaped magnetoresistance loops are observed by magneto-transport measurements with out-of-plane and in-plane fields, respectively, and can be correlated with the magnetization of the YIG substrate. More importantly, a magnetic signal from the Bi2Se3 up to 130 K is clearly observed by magneto-optical Kerr effect measurements. Our results demonstrate the proximity-induced TI magnetism at higher temperatures, an important step toward room-temperature application of TI-based spintronic devices.

16.
Phys Rev Lett ; 110(17): 177202, 2013 Apr 26.
Article in English | MEDLINE | ID: mdl-23679764

ABSTRACT

Thermally induced domain wall motion in a magnetic insulator was observed using spatiotemporally resolved polar magneto-optical Kerr effect microscopy. The following results were found: (i) the domain wall moves towards hot regime; (ii) a threshold temperature gradient (5 K/mm), i.e., a minimal temperature gradient required to induce domain wall motion; (iii) a finite domain wall velocity outside of the region with a temperature gradient, slowly decreasing as a function of distance, which is interpreted to result from the penetration of a magnonic current into the constant temperature region; and (iv) a linear dependence of the average domain wall velocity on temperature gradient, beyond a threshold thermal bias. Our observations can be qualitatively explained using a magnonic spin transfer torque mechanism, which suggests the utility of magnonic spin transfer torque for controlling magnetization dynamics.

17.
Ann Biomed Eng ; 41(1): 172-84, 2013 Jan.
Article in English | MEDLINE | ID: mdl-22810840

ABSTRACT

We compare the influence of time-frequency methods on analysis of time-varying renal autoregulation properties. Particularly, we examine if detection probabilities are similar for amplitude and frequency modulation for a modulated simulation signal among five time-frequency approaches, and if time-varying changes in system gain are detected using four approaches for estimating time-varying transfer functions. Detection of amplitude and frequency modulation varied among methods and was dependent upon background noise added to the simulated data. Three non-parametric time-frequency methods accurately detected modulation at low frequencies across noise levels but not high frequencies; while the converse was true for a fourth, and a fifth non-parametric approach was not capable of modulation detection. When applied to estimation of time-varying transfer functions, the parametric approach provided the most accurate estimations of system gain changes, detecting a 1 dB step increase. Application of the appropriate methods to laser Doppler recordings of cortical blood flow and arterial pressure data in anesthetized rats reaffirm the presence of time-varying dynamics in renal autoregulation. An increase in the peak system gain and detection of amplitude modulation of the Myogenic mechanism both occurred after inhibition of nitric oxide synthase, suggesting a connection between the operation of underlying regulators and system performance.


Subject(s)
Kidney/physiology , Models, Biological , Animals , Blood Pressure , Fourier Analysis , Homeostasis , Kidney/blood supply , Rats , Rats, Inbred SHR , Rats, Sprague-Dawley , Regional Blood Flow
18.
Hypertension ; 59(1): 158-66, 2012 Jan.
Article in English | MEDLINE | ID: mdl-22083158

ABSTRACT

It has been shown that endothelial NO synthase (eNOS) uncoupling occurs in hypertension and atherosclerosis. However, its causal role in vascular pathogenesis has not been characterized previously. Here, we challenged eNOS preuncoupled hyperphenylalaninemia (hph)-1 mice (deficient in eNOS cofactor tetrahydrobiopterin biosynthetic enzyme GTPCHI) with angiotensin II (Ang II; 0.7 mg/kg per day, 14 days). Both wild-type and hph-1 groups developed hypertension similarly up to day 6 to 7. Thereafter, ≈14% of Ang II-infused (0.7 mg/kg per day) hph-1 mice (n=72) started to die suddenly of ruptured abdominal aortic aneurysm (AAA). Among the survivors, 65% developed AAA, resulting in a total morbidity rate of 79%. In contrast, none of the Ang II-infused wild-type mice died or developed AAA. Ang II progressively deteriorated eNOS uncoupling in hph-1 mice while augmenting tetrahydrobiopterin and nitric oxide (NO(·)) deficiencies. The abundance of the tetrahydrobiopterin salvage enzyme dihydrofolate reductase in the endothelium was decreased in hph-1 mice and further diminished by Ang II infusion. Intriguingly, restoration of dihydrofolate reductase expression by oral administration of folic acid or overexpression of dihydrofolate reductase completely prevented AAA formation in Ang II-infused hph-1 mice while attenuating progressive uncoupling of eNOS. Folic acid also attenuated vascular remodeling and inflammation characterized by medial elastin breakdown and augmented matrix metalloproteinase 2 activity and activation of matrix metalloproteinase 9, as well as macrophage infiltration. In conclusion, these data innovatively suggest a causal role of eNOS uncoupling/tetrahydrobiopterin deficiency in AAA formation. Therefore, oral folic acid administration, endothelium-targeted dihydrofolate reductase gene therapy, and perhaps other countermeasures directed against eNOS uncoupling could be used as new therapeutics for AAA.


Subject(s)
Aortic Aneurysm, Abdominal/drug therapy , Aortic Aneurysm, Abdominal/metabolism , Folic Acid/pharmacology , GTP Cyclohydrolase/genetics , Nitric Oxide Synthase Type III/metabolism , Angiotensin II/pharmacology , Animals , Aortic Aneurysm, Abdominal/etiology , Aortic Rupture/drug therapy , Aortic Rupture/etiology , Aortic Rupture/metabolism , Biopterins/analogs & derivatives , Biopterins/metabolism , Blood Pressure/drug effects , Blood Pressure/physiology , Disease Models, Animal , GTP Cyclohydrolase/metabolism , Genetic Therapy/methods , Hypertension/chemically induced , Hypertension/metabolism , Mice , Mice, Inbred C57BL , Mice, Inbred CBA , Mice, Mutant Strains , Nitric Oxide/metabolism , Tetrahydrofolate Dehydrogenase/genetics , Vasoconstrictor Agents/pharmacology , Vitamin B Complex/pharmacology
19.
Langmuir ; 27(14): 8735-7, 2011 Jul 19.
Article in English | MEDLINE | ID: mdl-21668020

ABSTRACT

The application of steric blocking in surface science is exemplified by the control of surface patterns through the selective methylation of pentacenetetrone. Pentacenetetrones interact (with one another) on Cu(111) via intermolecular hydrogen bonding involving the carbonyl oxygen and the adjacent hydrogen atoms. Steric blocking of the intermolecular interaction by the successive insertion of inert methyl groups at terminal locations transforms a dense molecular pattern first into isolated double rows and eventually into single rows in a highly predictable fashion. Density functional theory modeling reveals the underlying energetics.

20.
J Am Chem Soc ; 132(39): 13578-81, 2010 Oct 06.
Article in English | MEDLINE | ID: mdl-20831159

ABSTRACT

The diffusion temperature of molecular 'walkers', molecules that are capable of moving unidirectionally across a substrate violating its symmetry, can be tuned over a wide range utilizing extension of their aromatic backbone, insertion of a second set of substrate linkers (converting bipedal into quadrupedal species), and substitution on the ring. Density functional theory simulation of the molecular dynamics identifies the motion of the quadrupedal species as pacing (as opposed to trotting or gliding). Knowledge about the diffusion mode allows us to draw conclusions on the relevance of tunneling to the surface diffusion of polyatomic organic molecules.


Subject(s)
Copper/chemistry , Molecular Dynamics Simulation , Organometallic Compounds/chemistry , Quinones/chemistry , Diffusion , Organometallic Compounds/chemical synthesis , Oxygen/chemistry , Surface Properties , Temperature , Vibration
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