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1.
ACS Macro Lett ; 13(3): 375-380, 2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38461421

RESUMO

Identifying the origin of scattering from polymer materials is crucial to infer structural features that can relate to functional properties. Here, we use our recently developed virtual-site coarse graining to accelerate atomistic simulations and show how various molecular features govern wide-angle X-ray scattering from a conjugated polymer, poly(3-hexylthiophene) (P3HT). The efficient molecular dynamics simulations can represent the structure and capture the emergence of crystalline order from amorphous melts upon cooling while retaining atomistic details of chain configurations. The scattering extracted from simulations shows good agreement with wide-angle X-ray scattering experiments. Amorphous P3HT exhibits broad scattering peaks: a high-q peak from interchain side-group correlations and a low-q peak from interchain backbone-backbone correlations. During amorphous to crystalline phase transitions, the distance between backbones along the side-group direction increases because of lack of interdigitation in the crystalline phase. Scattering from π-π stacking emerges only after crystallization takes place. Intrachain correlations contribute negligibly to the scattering from the amorphous and crystalline phases.

2.
J Colloid Interface Sci ; 530: 137-145, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-29966846

RESUMO

Lithium-Sulfur (Li-S) batteries are mostly known for their high energy density and cost-effectiveness. However, their intrinsic problems hinder their implementation into the marketplace. The most pronounced problems are the parasitic reactions which occur between lithium polysulfides species and lithium metal anode, the volume expansion of sulfur (80%) at the end of discharge and the safety issues which are linked with the use of lithium metal. Herein this work, two approaches are applied to prevent these effects; one approach is the use of Li2S as cathode material, instead of starting from sulfur powder, both to circumvent the volume expansion of sulfur taking place during discharge and to enable lithium-free anodes cell assembling (i.e. Si-Li2S or Sn-Li2S cell configurations). Second approach deals with the lithium anode protection by SnO2 containing freestanding pyrolyzed bacterial cellulose interlayers located between anode and cathode electrodes. Since bacterial celluloses are formed in the presence of SnO2 nanoparticles, the resulting structure enables intimate contact between carbon and SnO2 nanoparticles. By employing Li2S cathode and freestanding interlayer concurrently, 468 mAh g-1 discharge capacity is obtained at C/10 current density over 100 cycles.


Assuntos
Carbono/química , Celulose/química , Fontes de Energia Elétrica , Compostos de Lítio/química , Nanofibras/química , Nanopartículas/química , Sulfetos/química , Compostos de Estanho/química , Bactérias/química , Nanofibras/ultraestrutura , Nanopartículas/ultraestrutura , Polissacarídeos Bacterianos/química , Enxofre/química
3.
JAMA Neurol ; 70(1): 78-84, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23318515

RESUMO

OBJECTIVE: To identify new genes and risk factors associated with frontotemporal dementia (FTD). Several genes and loci have been associated with different forms of FTD, but a large number of families with dementia do not harbor mutations in these genes. DESIGN: Whole-exome sequencing and whole-genome genotyping were performed in all patients. Genetic variants obtained from whole-exome sequencing were integrated with the data obtained from whole-genome genotyping. SETTING: Database of the Behavioral Neurology Outpatient Clinic of the Department of Neurology, Istanbul Faculty of Medicine, Istanbul, Turkey. PATIENTS Forty-four Turkish patients with an FTD-like clinical diagnosis were included in the study. Relatives were screened when appropriate. MAIN OUTCOME MEASURE: Mutations in the triggering receptor expressed on myeloid cells 2 gene (TREM2). RESULTS: In 3 probands with FTD-like disease, we identified different homozygous mutations in TREM2 that had previously been associated with polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL). None of these 3 patients had a typical clinical presentation of PLOSL: they presented with behavioral change and subsequent cognitive impairment and motor features but without any bone cysts or bone-associated phenotypes. Imaging showed white matter abnormalities as well as frontal atrophy in all 3 patients. CONCLUSIONS: Our results show that TREM2 is responsible for an unexpectedly high number of dementia cases in our cohort, suggesting that this gene should be taken into account when mutations in other dementia genes are excluded. Even for complex syndromes such as dementia, exome sequencing has proven to be a rapid and cost-effective tool to identify genetic mutations, allowing for the association of clinical phenotypes with unexpected molecular underpinnings.


Assuntos
Exoma/genética , Demência Frontotemporal/genética , Glicoproteínas de Membrana/genética , Mutação/genética , Receptores Imunológicos/genética , Adulto , Demência Frontotemporal/patologia , Demência Frontotemporal/fisiopatologia , Humanos , Masculino , Fatores de Risco , Síndrome
4.
Parkinsonism Relat Disord ; 18(5): 562-6, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22445249

RESUMO

BACKGROUND: Parkin (PARK2) gene mutations are the predominant cause of autosomal recessive parkinsonism. Characteristic features include: early onset symptoms with slow clinical course, good response to low doses of levodopa, and frequently treatment-induced dyskinesia. Studies using a voxel-based morphometry approach showed a decrease in the gray matter volume of the basal ganglia in mutation carriers during the symptomatic stages. A bilateral, presumably compensatory increase of basal ganglia gray matter value was recently demonstrated in asymptomatic Parkin mutation carriers. Behavioral disorders including: anxiety, psychosis, panic attacks, depression, disturbed sexual, behavioral and obsessive-compulsive disorders have been reported in these patients. METHOD: A total of 28 Parkinson's Disease (PD) patients consisting of 10 Young-Onset without Parkin mutations (YOPD), 9 Young-Onset with Parkin mutations (YOPD-p), 9 Late-Onset without Parkin mutations (LOPD) and 32 healthy control subjects were studied with an automated volumetric assessment method to quantify subcortical atrophy. Patients but not controls also underwent a neuropsychological and neuropsychiatric assessment. RESULTS: Results revealed a reduction of bilateral caudate nuclei volumes in YOPD-p patients compared to the YOPD patients while there were no statistically significant differences between other groups. YOPD-p patients showed similar results to other patient groups on neuropsychiatric and neuropsychological evaluation measures. CONCLUSION: YOPD-p and YOPD patients showed a different pattern of volume changes in basal ganglia. Despite its relatively benign clinical course, carrying the Parkin mutation seems to be associated with greater atrophy in subcortical structures. Failure of compensatory mechanisms, different mutation types and pathophysiologic processes may underlie this diverse pattern of subcortical brain changes.


Assuntos
Gânglios da Base/patologia , Mutação/genética , Doença de Parkinson/genética , Doença de Parkinson/patologia , Ubiquitina-Proteína Ligases/genética , Adulto , Idade de Início , Idoso , Análise de Variância , Mapeamento Encefálico , Transtornos Cognitivos/etiologia , Transtornos Cognitivos/patologia , Feminino , Lateralidade Funcional , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Doença de Parkinson/complicações , Escalas de Graduação Psiquiátrica , Adulto Jovem
5.
Parkinsonism Relat Disord ; 18(2): 191-3, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22018912

RESUMO

We report two siblings that presented hypotonia and very early-onset parkinsonism. Homozygosity mapping using SNP genome scan data identified a candidate locus that was 12.2 Mega base pairs. By exome sequencing, we found a homozygous five-nucleotide deletion (c.448_452delAGAAC) in gene Sepiapterin Reductase (SPR). The mutation is predicted to lead to premature translational termination. Sepiapterin reductase deficiency (SRD) is a recently recognized dopa-responsive dystonia. Our findings show that SRD can manifest as early-onset parkinsonism, widening the spectrum of the disease phenotype and adding to the genetic heterogeneity of the disease.


Assuntos
Oxirredutases do Álcool/genética , Mutação da Fase de Leitura , Deleção de Genes , Homozigoto , Transtornos Parkinsonianos/genética , Adolescente , Adulto , Fatores Etários , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Transtornos Parkinsonianos/diagnóstico
6.
Neurobiol Aging ; 33(5): 1008.e17-23, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22153900

RESUMO

Alzheimer's disease (AD) is a genetically complex disorder for which the definite diagnosis is only accomplished postmortem. Mutations in 3 genes (APP, PSEN1, and PSEN2) are known to cause AD, but a large number of familial cases do not harbor mutations in these genes and several unidentified genes that contain disease-causing mutations are thought to exist. We performed whole exome sequencing in a Turkish patient clinically diagnosed with Alzheimer's disease from a consanguineous family with a complex history of neurological and immunological disorders and identified a mutation in NOTCH3 (p.R1231C), previously described as causing cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Complete screening of NOTCH3 in a cohort of 95 early onset AD cases and 95 controls did not reveal any additional pathogenic mutations. Although the complex history of disease in this family precluded us to establish segregation of the mutation found with disease, our results show that exome sequencing is a rapid, cost-effective and comprehensive tool to detect genetic mutations, allowing for the identification of unexpected genetic causes of clinical phenotypes. As etiological based therapeutics become more common, this method will be key in diagnosing and treating disease.


Assuntos
Doença de Alzheimer/genética , Exoma/genética , Receptores Notch/genética , Análise de Sequência de DNA , Adulto , Idoso , Idoso de 80 Anos ou mais , Saúde da Família , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , Mutação Puntual/genética , Receptor Notch3 , Turquia
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