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1.
BMC Nephrol ; 23(1): 9, 2022 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-34979961

RESUMO

People with type 1 and type 2 diabetes are at risk of developing progressive chronic kidney disease (CKD) and end-stage kidney failure. Hypertension is a major, reversible risk factor in people with diabetes for development of albuminuria, impaired kidney function, end-stage kidney disease and cardiovascular disease. Blood pressure control has been shown to be beneficial in people with diabetes in slowing progression of kidney disease and reducing cardiovascular events. However, randomised controlled trial evidence differs in type 1 and type 2 diabetes and different stages of CKD in terms of target blood pressure. Activation of the renin-angiotensin-aldosterone system (RAAS) is an important mechanism for the development and progression of CKD and cardiovascular disease. Randomised trials demonstrate that RAAS blockade is effective in preventing/ slowing progression of CKD and reducing cardiovascular events in people with type 1 and type 2 diabetes, albeit differently according to the stage of CKD. Emerging therapy with sodium glucose cotransporter-2 (SGLT-2) inhibitors, non-steroidal selective mineralocorticoid antagonists and endothelin-A receptor antagonists have been shown in randomised trials to lower blood pressure and further reduce the risk of progression of CKD and cardiovascular disease in people with type 2 diabetes. This guideline reviews the current evidence and makes recommendations about blood pressure control and the use of RAAS-blocking agents in different stages of CKD in people with both type 1 and type 2 diabetes.


Assuntos
Anti-Hipertensivos/uso terapêutico , Angiopatias Diabéticas/tratamento farmacológico , Nefropatias Diabéticas/tratamento farmacológico , Hipertensão/tratamento farmacológico , Sistema Renina-Angiotensina/efeitos dos fármacos , Adulto , Albuminúria , Monitorização Ambulatorial da Pressão Arterial , Diabetes Mellitus Tipo 1/complicações , Diabetes Mellitus Tipo 2/complicações , Angiopatias Diabéticas/fisiopatologia , Angiopatias Diabéticas/urina , Nefropatias Diabéticas/fisiopatologia , Nefropatias Diabéticas/urina , Humanos , Hipertensão/fisiopatologia , Hipertensão/urina , Cooperação do Paciente , Comportamento de Redução do Risco , Reino Unido
3.
Phys Rev Lett ; 125(26): 267202, 2020 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-33449718

RESUMO

We report gapless quantum spin liquid behavior in the layered triangular Sr_{3}CuSb_{2}O_{9} system. X-ray diffraction shows superlattice reflections associated with atomic site ordering into triangular Cu planes well separated by Sb planes. Muon spin relaxation measurements show that the S=1/2 moments at the magnetically active Cu sites remain dynamic down to 65 mK in spite of a large antiferromagnetic exchange scale evidenced by a large Curie-Weiss temperature θ_{CW}≃-143 K as extracted from the bulk susceptibility. Specific heat measurements also show no sign of long-range order down to 0.35 K. The magnetic specific heat (C_{m}) below 5 K reveals a C_{m}=γT+αT^{2} behavior. The significant T^{2} contribution to the magnetic specific heat invites a phenomenology in terms of the so-called Dirac spinon excitations with a linear dispersion. From the low-T specific heat data, we estimate the dominant exchange scale to be ∼36 K using a Dirac spin liquid ansatz which is not far from the values inferred from microscopic density functional theory calculations (∼45 K) as well as high-temperature susceptibility analysis (∼70 K). The linear specific heat coefficient is about 18 mJ/mol K^{2} which is somewhat larger than for typical Fermi liquids.

4.
Phys Rev Lett ; 123(1): 017201, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31386398

RESUMO

Investigation of elementary excitations has advanced our understanding of many-body physics governing most physical properties of matter. Recently spin-orbit excitons have drawn much attention, whose condensates near phase transitions exhibit Higgs mode oscillations, a long-sought-after physical phenomenon [A. Jain, et al., Nat. Phys. 13, 633 (2017)NPAHAX1745-247310.1038/nphys4077]. These critical transition points, resulting from competing spin-orbit coupling (SOC), local crystalline symmetry, and exchange interactions, are not obvious in iridium-based materials, where SOC prevails in general. Here, we present results of resonant inelastic x-ray scattering on a spin-orbital liquid Ba_{3}ZnIr_{2}O_{9} and three other 6H-hexagonal perovskite iridates that show magnetism, contrary to the nonmagnetic singlet ground state expected due to strong SOC. Our results show that substantial hopping between closely placed Ir^{5+} ions within Ir_{2}O_{9} dimers in these 6H iridates modifies spin-orbit coupled states and reduces spin-orbit excitation energies. Here, we are forced to use at least a two-site model to match the excitation spectrum going in-line with the strong intradimer hopping. Apart from SOC, low-energy physics of iridates is thus critically dependent on hopping and may not be ignored even for systems having moderate hopping, where the excitation spectra can be explained using an atomic model. SOC, which is generally found to be 0.4-0.5 eV in iridates, is scaled in effect down to ∼0.26 eV for the 6H systems, sustaining the hope of achieving quantum criticality by tuning Ir-Ir separation.

5.
Arch Virol ; 164(4): 1005-1013, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30734111

RESUMO

Rice crops in South and Southeast Asian countries suffer critical yield losses due to rice tungro disease caused by joint infection with rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV). Previously, for generating RNA interference-based transgenic resistance against tungro viruses, RTBV ORF IV was used as a transgene to develop RTBV resistance in a popular high-yielding scented rice variety. The transgene from this line was then introgressed into five popular high-yielding but tungro-susceptible rice varieties by marker-assisted backcross breeding with a view to combine the resistant trait with the agronomic traits. The present work includes a resistance assay of the BC3F5 lines of these varieties under glasshouse conditions. Out of a total of 28 lines tested, each consisting of 12 individual plants, eight lines showed significant amelioration in height reduction and 100- to 1000-fold reduction in RTBV titers. The RNAi-mediated resistance was clearly manifested by the presence of virus-derived small RNA (vsRNA) specific for RTBV ORF IV in the transgenic backcrossed lines.


Assuntos
Resistência à Doença , Oryza/imunologia , Doenças das Plantas/virologia , Plantas Geneticamente Modificadas/imunologia , Tungrovirus/fisiologia , Proteínas Virais/genética , Índia , Oryza/genética , Oryza/virologia , Doenças das Plantas/imunologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/virologia , Interferência de RNA , Transgenes , Tungrovirus/genética , Tungrovirus/isolamento & purificação , Proteínas Virais/metabolismo , Waikavirus/genética , Waikavirus/metabolismo
6.
J Phys Condens Matter ; 28(37): 375501, 2016 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-27419390

RESUMO

We have studied the electronic structure and magnetism of the spin chain compounds Ca3ZnMnO6 and Ca3ZnCoO6 using density functional theory with generalised gradient approximation (GGA). In agreement with experiment our calculations reveal that high spin (HS) state for Mn(4+) ion and low spin (LS) state for Co(4+) ion stabilize the magnetic structure of the respective compounds. The magnetic exchange paths, calculated using Nth order muffin-tin orbital downfolding method, shows dominant intra-chain exchange interaction between the magnetic ions (Mn, Co) is antiferromagnetic for Ca3ZnMnO6 and ferromagnetic for Ca3ZnCoO6. The magnetic order of both the compounds is in accordance with the Goodenough-Kanamori-Anderson rules and is consistent with the experimental results. Finally we have investigated the importance of spin-orbit coupling (SOC) in these compounds. While SOC practically has no effect for the Mn system, it is strong enough to favor the spin quantization along the chain direction for the Co system in the LS state.

7.
Virology ; 495: 101-11, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27183330

RESUMO

Geminiviruses constitute one of the largest groups of plant viruses, having characteristic twinned geminate particles encapsidating small circular single-stranded DNA molecules. Geminiviral promoters are generally located within the intergenic region, although promoters have also been detected within the genes. Similarly, the geminivirus-associated betasatellite also harbours a promoter element for driving the expression of its only ORF. These regulatory elements of geminiviral and satellite origins have been subject of great interest to develop heterologous gene expression modules. Geminiviral promoter and regulatory elements show a complex regulation that is mediated by several host as well as viral proteins. Here, the structural and functional features of geminiviral and satellite promoters are discussed along with their regulation by plant and viral proteins. Although generalization in many cases is difficult and demands further studies, a pattern is seen to emerge on the regulation of the promoters.


Assuntos
DNA Viral , Geminiviridae/fisiologia , Regulação Viral da Expressão Gênica , Genoma Viral , Regiões Promotoras Genéticas , Ordem dos Genes , Inativação Gênica , Sequências Reguladoras de Ácido Nucleico , Transcrição Gênica , Ativação Transcricional , Proteínas Virais/genética , Proteínas Virais/metabolismo
8.
Virus Genes ; 52(4): 521-9, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26983604

RESUMO

Severe losses of rice yield in south and southeast Asia are caused by Rice tungro disease (RTD) induced by mixed infection of Rice tungro bacilliform virus (RTBV) and Rice tungro spherical virus (RTSV). In order to develop transgene-based resistance against RTBV, one of its genes, ORF IV, was used to generate transgenic resistance based on RNA-interference in the easily transformed rice variety Pusa Basmati-1, and the transgene was subsequently introgressed to rice variety ASD 16, a variety popular in southern India, using transgene marker-assisted selection. Here, we report the evaluation of BC3F4 and BC3F5 generation rice plants for resistance to RTBV as well as for agronomic traits under glasshouse conditions. The BC3F4 and BC3F5 generation rice plants tested showed variable levels of resistance, which was manifested by an average of twofold amelioration in height reduction, 1.5-fold decrease in the reduction in chlorophyll content, and 100- to 10,000-fold reduction in the titers of RTBV, but no reduction of RTSV titers, in three backcrossed lines when compared with the ASD 16 parent. Agronomic traits of some of the backcrossed lines recorded substantial improvements when compared with the ASD 16 parental line after inoculation by RTBV and RTSV. This work represents an important step in transferring RTD resistance to a susceptible popular rice variety, hence enhancing its yield in areas threatened by the disease.


Assuntos
Resistência à Doença/genética , Genes de Plantas/genética , Oryza/virologia , Doenças das Plantas/genética , Transgenes/genética , Waikavirus/genética , Cruzamento , Índia , Fases de Leitura Aberta/genética , Oryza/genética , Doenças das Plantas/virologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/virologia , Interferência de RNA/fisiologia , RNA Viral/genética
9.
Eur J Vasc Endovasc Surg ; 51(1): 134-40, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26775626

RESUMO

OBJECTIVES: The aim was to study primary failure, maturation times, and survival of common arteriovenous fistulae (AVF) to aid planning for vascular access, and to assess which strategy results in most dialysis days. METHODS: This was a longitudinal cohort study. Two databases of access operations and dialysis sessions over 9 years with 12-year follow-up were reviewed. Functional dialysis use is defined as achieving six consecutive dialysis sessions with two needles on AVF. Primary failure (PF) is failure to achieve functional dialysis use. Maturation time, calculated only for patients on dialysis with a central line at AVF operation, is defined from the operation date to the functional dialysis date. Cumulative patency, including PF, is calculated from the operation to date of AVF abandonment and is compared using Kaplan­Meier curves and adjusted hazard ratios (HRs). RESULTS: A total of 1206 AVF, 689 (57%) radiocephalic AVF (RCAVF), 383 (32%) brachiocephalic AVF (BCAVF), and 134 (11%) brachiobasilic AVF (BBAVF), were analysed. PF was 23%. PF was lower for BCAVF (17%) than RCAVF (26%) and BBAVF (26%) (p = .006). PF was higher for women (OR 1.59, 95% CI: 1.21­2.09) and patients with vascular kidney disease (OR 1.69, 95% CI: 1.19­2.59). Median maturation time was 10.3 weeks. Cumulative patency was worse for BCAVF (HR 1.36, 95% CI: 1.03­1.81) and BBAVF (HR 1.63 95% CI: 1.12­2.38), for patients on dialysis at AVF creation (HR 1.55, 95% CI: 1.13­2.12), and diabetics (HR 1.55, 95% CI: 1.12­1.85). RCAVFs resulted in 3% more dialysis-person-years (py) per 100 operations for all patients and in 15% more dialysis-py in the over 80s. CONCLUSION: RCAVFs have higher PF, but better survival than other AVF, and result in more dialysis time. AVF created pre-dialysis have better survival. An average maturation time of 10 weeks should be considered if planning to start dialysis on an AVF.


Assuntos
Derivação Arteriovenosa Cirúrgica , Avaliação de Processos em Cuidados de Saúde , Diálise Renal , Idoso , Idoso de 80 Anos ou mais , Derivação Arteriovenosa Cirúrgica/efeitos adversos , Bases de Dados Factuais , Inglaterra , Feminino , Humanos , Estimativa de Kaplan-Meier , Modelos Logísticos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Complicações Pós-Operatórias/etiologia , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento , Grau de Desobstrução Vascular
10.
J Hum Hypertens ; 30(6): 386-91, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26377355

RESUMO

White coat hypertension (WCH) is common and termed white coat effect (WCE) in those on treatment for hypertension. The UK guideline suggests that all patients in stage 1 and 2 hypertension, but not stage 3 hypertension, should have ambulatory blood pressure monitoring (ABPM) performed before commencing treatment. The relationship between office blood pressure (BP) and ABPM and the factors that influence the WCE were examined in a large British cohort (n=2056) from 2 hypertension clinics (1998-2011). Data were collected prospectively: the median age was 56 years: 53% were female, 76% Caucasian, 9% African Caribbean, 15% South Asian and 86% taking antihypertensives. Fifty-one percent had WCE and differences between clinic BP and ABPM measurements increased with the stage of hypertension varying from 2/4 (normotensive), 13/10 (stage 1 hypertension), 24/14 (stage 2) and 40/20 mm Hg (stage 3). The degree of difference is greater in this study than described in other populations. A positive correlation was found between clinic systolic and diastolic BP and the WCE (r=0.74 and r=0.56, respectively, P<0.0001). Significant (P<0.05) independent associations of systolic WCE were clinic systolic BP (ß=0.707), Caucasian ethnicity (South Asian ß=-0.06; African Caribbean ß=-0.043), female gender (male ß=-0.047), nonsmoking status (smoker ß=-0.100) and reduced renal function (estimated glomerular filtration rate ß=-0.036). Significant independent associations of diastolic WCH were clinic diastolic BP (ß=0.624), age (ß=0.207), female gender (male ß=-0.104), Caucasian ethnicity (South Asian ß=-0.052, African Caribbean ß=-0.079) and being a nonsmoker (ß=-0.082) or ex-smoker (ß=0.046). The results support current UK guidelines but suggest those with stage 3 hypertension would also benefit from ABPM.


Assuntos
Pressão Sanguínea , Ambulatório Hospitalar , Hipertensão do Jaleco Branco/etnologia , Adulto , Idoso , Anti-Hipertensivos/uso terapêutico , Pressão Sanguínea/efeitos dos fármacos , Monitorização Ambulatorial da Pressão Arterial , Inglaterra/epidemiologia , Feminino , Hospitais de Ensino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prevalência , Grupos Raciais , Medição de Risco , Fatores de Risco , Fatores de Tempo , Hipertensão do Jaleco Branco/diagnóstico , Hipertensão do Jaleco Branco/tratamento farmacológico , Hipertensão do Jaleco Branco/fisiopatologia
11.
J Hum Hypertens ; 30(2): 83-9, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25947275

RESUMO

Resistant hypertension is common among the hypertensive population with reported prevalence of 12 to 15%. These patients have a higher cardiovascular risk and consequently a poorer cardiovascular prognosis. Suboptimal adherence with antihypertensive medication is a common contributing factor in apparent treatment-resistant hypertension. Patients were observed taking their medications under direct supervision at our directly observed therapy (DOT) clinic. At the DOT clinic visit, patients were fitted with a 24-h ambulatory blood pressure (ABP) monitor and each drug, at currently prescribed dose, was administered by a nurse; at an hourly interval and patient observed for 7 h. ABP readings between pre and post DOT clinic were compared. Fifty out of 56 patients had complete data on the ABP. Twenty four were female and the mean (s.d.) age was 62.0 (11.0) years. On the basis of the study methods that differentiated patients according to their BP response during the DOT clinic, twenty-five (50.0%) patients were deemed to be truly resistant (24-h ambulatory systolic blood pressure (SBP) fall <5 mm Hg) and the remaining 25 were deemed to have clinically significant non-adherence (24-h ambulatory SBP fall ⩾5 mm Hg) to prescribed therapy. In non-adherent patients, the mean 24-h ambulatory BP drop observed was 19.5/9.4 mm Hg (P<0.001 for both). Our results suggest that non-adherence is very common among patients considered to have apparent treatment-resistant hypertension. DOT clinic can be an effective method of identifying the truly resistant hypertensive patients.


Assuntos
Anti-Hipertensivos/uso terapêutico , Hipertensão/tratamento farmacológico , Adesão à Medicação/estatística & dados numéricos , Pressão Sanguínea/efeitos dos fármacos , Monitorização Ambulatorial da Pressão Arterial , Terapia Diretamente Observada , Feminino , Seguimentos , Humanos , Hipertensão/epidemiologia , Hipertensão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Prevalência , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Reino Unido/epidemiologia
12.
J Phys Condens Matter ; 27(42): 426001, 2015 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-26436635

RESUMO

We investigate the magnetic, thermal, and dielectric properties of SrCuTe2O6, which is isostructural to PbCuTe2O6, a recently found, Cu-based 3D frustrated magnet with a corner-sharing triangular spin network having dominant first and second nearest neighbor (nn) couplings (Koteswararao et al 2014 Phys. Rev. B 90 035141). Although SrCuTe2O6 has a structurally similar spin network, the magnetic data exhibit the characteristic features of a typical quasi-1D magnet, which mainly resulted from the magnetically dominant third nn coupling, uniform chains. The magnetic properties of this system are studied via magnetization (M), heat capacity (C p ), dielectric constant ([Formula: see text]), and measurements along with ab initio band structure calculations. The magnetic susceptibility [Formula: see text] data show a broad maximum at 32 K and the system orders at low temperatures [Formula: see text] K and [Formula: see text] K, respectively. The analysis of the [Formula: see text] data gives an intra-chain coupling, [Formula: see text], to be about ≈ - 42 K with non-negligible frustrated inter-chain couplings ([Formula: see text] and [Formula: see text]). The hopping parameters obtained from the LDA band structure calculations also suggest the presence of coupled uniform chains. The observation of simultaneous anomalies in [Formula: see text] at [Formula: see text] and [Formula: see text] suggests the presence of a magneto-dielectric effect in SrCuTe2O6. A magnetic phase diagram is also built based on the M, C p , and [Formula: see text] results.

13.
Acta Virol ; 59(1): 57-63, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25790052

RESUMO

The complete nucleotide sequence of Sri Lankan cassava mosaic virus (SLCMV) DNA-A isolated from cassava in southern India was analyzed, a phylogenetic analysis with other begomoviral nucleotide sequences was performed and an efficient inoculation method of Nicotiana benthamiana with the cloned DNA was developed utilizing a biolistic device. The nucleotide sequence showed the conservation of all functional begomoviral protein domains and aligned most closely with begomoviruses reported from the Indian subcontinent, except for begomoviruses of cucurbits and legumes. Upon biolistic inoculation of N. benthamiana with the cloned DNA, most plants became symptomatic and showed the accumulation of viral DNA within 21-28 days post-inoculation.


Assuntos
Begomovirus/classificação , Begomovirus/patogenicidade , Nicotiana/virologia , Filogenia , Doenças das Plantas/virologia , Begomovirus/genética , Begomovirus/isolamento & purificação , Biolística , DNA Viral/genética , DNA Viral/metabolismo , Índia , Manihot/virologia , Dados de Sequência Molecular , Virulência
14.
Indian J Nephrol ; 25(1): 21-6, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25684868

RESUMO

There is increased cardiovascular (CV) mortality in subjects with chronic kidney disease (CKD). Arterial stiffness in these subjects is increased when compared to a healthy population. Markers of arterial stiffness and intima media thickness (IMT) are predictors of CV mortality. The aim of this study was to investigate whether there is any difference in markers of arterial stiffness and IMT between subjects with normal renal function and those with mild renal disease. The arterial distension waveform, IMT, diameter, and brachial blood pressure were measured to calculate Young's modulus (E) and elastic modulus (Ep) in the common carotid arteries of subjects with normal kidney function (estimated glomerular filtration rate [eGFR] >90) and those mild CKD (stage 2, eGFR 89-60). Data were available for 15 patients with normal kidney function and 29 patients with mild CKD. The subjects with mild CKD were older, but other co-variables were not significantly different. Both arterial wall stiffness parameters (E and Ep), but not IMT were significantly higher in the mild CKD group. Logistic regression demonstrated that only the arterial wall stiffness parameters (Ep and E) were independently associated with mild renal disease compared with normal, in a model adjusting for sex, age and diabetes and history of cardiovascular disease (CVD). E and Ep may be early markers of CVD in subjects with mild CKD that may manifest change before other more recognized markers such as IMT and pulse pressure.

16.
Indian J Nephrol ; 24(3): 139-40, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-25120289
17.
J Virol Methods ; 203: 9-14, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24675064

RESUMO

Citrus yellow mosaic badnavirus (CMBV) is an important pathogen in southern India spread by infected citrus propagules. One of the measures to arrest the spread of CMBV is to develop methods to screen and certify citrus propagules as CMBV-free. The methods loop-mediated isothermal amplification (LAMP) and SYBR green real-time PCR (SGRTPCR) have been developed for the efficient detection of CMBV in citrus propagules. This paper compares the sensitivities of LAMP and SGRTPCR with polymerase chain reaction (PCR) for the detection of CMBV. Whereas PCR and LAMP were able to detect CMBV from a minimum of 10 ng of total DNA of infected leaf samples, SGRTPCR could detect the same from 1 ng of total DNA. Using SGRTPCR, the viral titres were estimated to be the highest in rough lemon and lowest in Nagpur Mandarin of the five naturally infected citrus species tested. The results will help in designing suitable strategies for the sensitive detection of CMBV from citrus propagules.


Assuntos
Badnavirus/isolamento & purificação , Citrus/virologia , Técnicas de Amplificação de Ácido Nucleico/métodos , Badnavirus/genética , Benzotiazóis , Diaminas , Índia , Compostos Orgânicos/metabolismo , Doenças das Plantas/virologia , Quinolinas , Sensibilidade e Especificidade , Coloração e Rotulagem/métodos , Temperatura
18.
Sci Rep ; 3: 2995, 2013 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-24141233

RESUMO

NiS, exhibiting a text-book example of a first-order transition with many unusual properties at low temperatures, has been variously described in terms of conflicting descriptions of its ground state during the past several decades. We calculate these physical properties within first-principle approaches based on the density functional theory and conclusively establish that all experimental data can be understood in terms of a rather unusual ground state of NiS that is best described as a self-doped, nearly compensated, antiferromagnetic metal, resolving the age-old controversy. We trace the origin of this novel ground state to the specific details of the crystal structure, band dispersions and a sizable Coulomb interaction strength that is still sub-critical to drive the system in to an insulating state. We also show how the specific antiferromagnetic structure is a consequence of the less-discussed 90° and less than 90° superexchange interactions built in to such crystal structures.

19.
J Phys Condens Matter ; 25(33): 336003, 2013 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-23881047

RESUMO

We have synthesized polycrystalline and single-crystal samples of PbCu3TeO7 and studied its properties via magnetic susceptibility, χ(T), and heat-capacity, Cp(T), measurements and also electronic structure calculations. Whereas the crystal structure is suggestive of the presence of a quasi-2D network of Cu(2+) (S = 1/2) buckled staircase kagome layers, the χ(T) data show magnetic anisotropy and three magnetic anomalies at temperatures TN1 âˆ¼ 36 K, TN2 âˆ¼ 25 K, and TN3 âˆ¼ 17 K. The χ(T) data follow the Curie-Weiss law above 200 K and a Curie-Weiss temperature θCW âˆ¼- 150 K is obtained. The data deviate from the simple Curie-Weiss law below 200 K, which is well above TN1, suggesting the presence of competing magnetic interactions. The magnetic anomaly at TN3 appears to be of first order from magnetization measurements, although our Cp(T) results do not display any anomaly at TN3. The hopping integrals obtained from our electronic structure calculations suggest the presence of significant intra-kagome (next-nearest neighbor and diagonal) and inter-kagome couplings. These couplings take the PbCu3TeO7 system away from a disordered ground state and lead to long-range order, in contrast to what might be expected for an ideal (isotropic) 2D kagome system.

20.
Virus Genes ; 45(3): 600-5, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22926812

RESUMO

Citrus yellow mosaic badna virus (CMBV), a member of the Family Caulimoviridae, Genus Badnavirus is the causative agent of mosaic disease among Citrus species in southern India. Despite its reported prevalence in several citrus species, complete information on clear functional genomics or functional information of full-length genomes from all the CMBV isolates infecting citrus species are not available in publicly accessible databases. CMBV isolates from Rough Lemon and Sweet Orange collected from a nursery were cloned and sequenced. The analysis revealed high sequence homology of the two CMBV isolates with previously reported CMBV sequences implying that they represent new variants. Based on computational analysis of the predicted secondary structures, the possible functions of some CMBV proteins have been analyzed.


Assuntos
Badnavirus/genética , Citrus sinensis/virologia , Genoma Viral , Doenças das Plantas/virologia , Sequência de Aminoácidos , Badnavirus/classificação , Badnavirus/isolamento & purificação , Badnavirus/patogenicidade , Clonagem Molecular , Biologia Computacional , Sequência Consenso , DNA Viral/genética , Bases de Dados Genéticas , Índia , Dados de Sequência Molecular , Fases de Leitura Aberta , Filogenia , Estrutura Secundária de Proteína , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos
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