Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 103
Filtrar
1.
Chemistry ; 29(2): e202202916, 2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36237174

RESUMO

Dielectric switches have drawn renewed attention to the study of their many potential applications with the adjustable switch temperatures (Ts ). Herein, a novel antimony-based halide semiconductor, (N,N-diisopropylethylamine) tetrachloroantimonate ((DIPEA)SbCl4 , DIPEA+ =N,N-diisopropylethylamine), with dielectric relaxation behavior and dielectric switches has been successfully synthesized. This compound, consisting of coordinated anion S b C l 4 ∞ - ${{\left[{{\rm S}{\rm b}{\rm C}{\rm l}}_{4}\right]}_{\infty }^{-}}$ chains and isolated DIPEA+ cations, undergoes an isostructural order-disorder phase transition and shows a step-like dielectric anomaly, which can function as a frequency-tuned dielectric switch with highly adjustable switch temperature (Ts ). Variable-temperature single-crystal structure analyses and first-principles molecular dynamics simulations give information about the general mechanisms of molecular dynamics. This work enriches the dielectric switch family and proves that hybrid metal halides are promising candidates for switchable physical or chemical properties.

2.
J Magn Reson Imaging ; 57(1): 85-94, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-35648113

RESUMO

BACKGROUND: Disagreement in assessments of Ki67 expression based on core-needle biopsy and matched surgical samples complicates decisions in the treatment of breast cancer. PURPOSE: To examine whether preoperative breast MRI could be useful in predicting Ki67 discordance between core-needle biopsy and surgical samples. STUDY TYPE: Retrospective. POPULATION: Three hundred and sixty-five breast cancer patients with MRI scans and having both core-needle biopsy and surgical samples from 2017 to 2019. FIELD STRENGTH/SEQUENCE: 3.0 T, T2-weighted iterative decomposition of water and fat with echo asymmetry and least squares estimation sequence, diffusion-weighted sequence using b-values 0/1000, dynamic contrast enhanced image by volume imaged breast assessme NT. ASSESSMENT: We collected clinicopathologic variables and preoperative MRI features (tumor size, lesion type, shape of mass, spiculated margin, internal enhancement, peri-tumoral edema, intra-tumoral necrosis, multifocal/multicentric, apparent diffusion coefficient [ADC] minimum, ADC mean, ADC maximum, ADC difference). STATISTICAL TESTS: K-means clustering, multivariable logistic regression, receiver operating characteristic curve. RESULTS: Sixty-one patients showed Ki67 discordance and 304 patients show Ki67 concordance according to our definition using K-means clustering. Multivariable regression analysis showed that the following parameters were independently associated with Ki67 discordance: peri-tumoral edema, odds ratio (OR) 2.662, 95% confidence interval (CI) 1.432-4.948; ADCmin ≤ 0.829 × 10-3  mm2 /sec, OR 2.180, 95% CI 1.075-4.418; and ADCdiff > 0.317 × 10-3  mm2 /sec, OR 3.365, 95% CI 1.698-6.669. This multivariable model resulted in an AUC of 0.758 (95% CI 0.711-0.802) with sensitivity and specificity being 0.803 and 0.621, respectively. CONCLUSION: Presence of peri-tumoral edema, smaller ADCmin and greater ADCdiff in preoperative breast MRI may indicate high risk of Ki67 discordance between core-needle biopsy and surgical samples. For patients with these MRI-based risk factors, clinicians should not rely on Ki67 assessment only from core-needle biopsy.


Assuntos
Neoplasias da Mama , Mama , Humanos , Feminino , Biópsia com Agulha de Grande Calibre , Estudos Retrospectivos , Mama/patologia , Imageamento por Ressonância Magnética , Imagem de Difusão por Ressonância Magnética/métodos , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/cirurgia , Neoplasias da Mama/metabolismo
3.
Phys Chem Chem Phys ; 25(35): 23678-23684, 2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37610335

RESUMO

Two-dimensional covalent organic frameworks (COFs) have always been a hot topic in condensed matter physics. Herein, the first 100 excited states of the TPPA-COF are calculated to investigate the optical absorption properties of the materials in the interval. The stable molecular structure of monolayer TPPA-COF is obtained by first-principles calculation, which can be regarded as a hexagon with an aperture size of 18.25 Å. By means of the band structure and density of state analysis, it is found that the monolayer band gap width of the TPPA-COF is 1.52 eV. All excited states of the TPPA-COF exhibit obvious pi → pi* (delocalized π to anti π) local excitation characteristics through analysing the spatial distribution of the electron-hole pairs of the 10 excited states with the highest oscillator strength among the first 100 excited states. In addition, the simulated UV-vis spectra show that the maximum absorption intensity of the TPPA-COF is about 357 684 mol-1 cm-1, indicating that the TPPA-COF is a potential light-absorbing material.

4.
Intervirology ; 65(1): 37-48, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34695827

RESUMO

INTRODUCTION: Virus-like particles (VLPs), self-assembled multiprotein structures, can stimulate robust immune responses due to their structural similarity to native virions that allow the presentation of multiple copies of the target epitopes. Utilizing VLPs as vaccine platforms to present exogenous antigens is a promising and challenging approach in the vaccine development field. This study investigates the potential of the truncated hepatitis E virus (HEV) capsid as a VLP platform to present foreign antigens. METHODS: The S and M domains of the HEV capsid protein were selected as the optimal carrier (CaSM). The exogenous antigen Seq8 containing 3 neutralizing epitopes from 3 different foot-and-mouth disease virus (FMDV) strains was linked to the C-terminal of CaSM to construct a chimeric VLP (CaSM-Seq8). The chimeric particles were produced in Escherichia coli, and their morphology, physicochemical properties, antigenicity, and immunogenicity were analyzed. RESULTS: Morphological analysis showed that CaSM-Seq8 self-assembled into VLPs similar to CaSM VLPs (∼26 nm in diameter) but smaller than native HEV virions. Further, the thermal stability and the resistance to enzymatic proteolysis of Seq8 were enhanced when it was attached to the CaSM carrier. The antigenicity analysis revealed a more robust reactivity against anti-FMDV antibodies when Seq8 was presented on CaSM particles. Upon injection into mice, FMDV-specific IgGs induced by CaSM-Seq8 appeared earlier, increased faster, and maintained higher levels for a longer time than those induced by Seq8 alone or the inactivated FMDV vaccine. CONCLUSION: This study demonstrated the potential of utilizing the truncated HEV capsid as an antigen-presenting platform for the development of chimeric VLP immunogens.


Assuntos
Vírus da Febre Aftosa , Vírus da Hepatite E , Vacinas de Partículas Semelhantes a Vírus , Animais , Capsídeo , Proteínas do Capsídeo/genética , Vírus da Hepatite E/genética , Camundongos , Desenvolvimento de Vacinas , Vacinas de Partículas Semelhantes a Vírus/genética
5.
Inorg Chem ; 61(37): 14770-14777, 2022 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-36070603

RESUMO

Due to their important role in biological systems, it is urgent to develop a material that can rapidly and sensitively detect the concentration of Fe3+ and Al3+ ions. In this work, a brand-new CdII-based metal-organic framework [Cd(BTBD)2(AIC)]n (JXUST-18, BTBD = 4,7-bis(1H-1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole and H2AIC = 5-aminoisophthalic acid) with a 4-connected sql topology was designed and synthesized. The symmetrical CdII centers are linked by AIC2- ligands with µ3-η1:η1:η1:η1 coordination mode to form a [Cd2(COO)2] secondary building unit (SBU). The contiguous SBUs are further connected by BTBD ligands to form a two-dimensional (2D) layer structure. JXUST-18 can remain stable in aqueous solutions with pH values of 3-12 or in boiling water. Luminescent experiments suggest that JXUST-18 displays more than eightfold fluorescence enhancement in the presence of Fe3+ and Al3+ ions, and the detection limits for Fe3+ and Al3+ ions are 0.196 and 0.184 µM, respectively. Furthermore, the change in luminescence color is uncomplicatedly distinguishable with the naked eye under ultraviolet light at 365 nm. In addition, a series of devices based on JXUST-18 including fluorescence test strips, lamp beads, and composite films were developed to detect metal ions via visual changes in luminescence color. Significantly, JXUST-18 is a rare MOF-based turn-on fluorescence sensor for the detection of Fe3+ ions. The theoretical calculation suggests that the complexation of Fe3+/Al3+ ions and the -NH2 group contributes to fluorescence enhancement.

6.
Sheng Li Xue Bao ; 74(3): 469-478, 2022 Jun 25.
Artigo em Chinês | MEDLINE | ID: mdl-35770644

RESUMO

Mesenchymal stem cells (MSCs) are a class of pluripotent cells that can self-renew and differentiate. Numerous studies have shown that MSCs have important roles in areas such as regenerative medicine and tissue engineering. However, it is worth noting that MSCs will gradually age during long-term in vitro expansion with decreased stemness such as weakened migration ability, slowed proliferation rate and decreased differentiation potential, which greatly hinders the application of MSCs. Currently, the microenvironment for cell growth is recognized as one of the factors causing senescence in MSCs. Recent studies point out that the latest technologies such as exogenous administration, oxygen concentration regulation and extracellular matrix (ECM) construction can delay stem cell senescence by simulating or regulating the microenvironment. Here, we review the current knowledge of the characteristics and molecular mechanisms of senescent MSCs and microenvironment strategies to maintain MSCs stemness, which can provide a reference for future large-scale application of MSCs preparations in tissue engineering and clinical studies.


Assuntos
Células-Tronco Mesenquimais , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Senescência Celular , Matriz Extracelular
7.
Chemistry ; 27(63): 15716-15721, 2021 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-34498317

RESUMO

The multifunctional two-dimensional (2D) organic-inorganic hybrid perovskites have potential applications in many fields, such as, semiconductor, energy storage and fluorescent device etc. Here, a 2D Ruddlesden-Popper (RP) perovskite (IPA)2 (FA)Pb2 I7 (1, IPA+ =C3 H9 NI+ , FA+ =CN2 H5 + ) is determined for its photophysical properties. Strikingly, 1 reveals a solid reversible phase transition with Tc of 382 K accompanied by giant entropy change of 40 J mol-1 K-1 . Further optical investigations indicate that 1 reveals a narrow direct bandgap (2.024 eV) attributed to the slight bending of I-Pb-I edge and inorganic [Pb2 I7 ]n layer and a superior photoluminescence (PL) emission with super long lifetime of 0.1607 ms. It is believed that this work will pave an avenue to further design multifunctional semiconductors that combines energy storage and photoelectric materials.

8.
Inorg Chem ; 60(2): 1195-1201, 2021 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-33356190

RESUMO

Due to the existence of some cross properties such as SHG (second-harmonic generation), ferroelectricity, piezoelectricity, and thermoelectricity, molecular ferroelectrics have been widely used as a composite multipurpose material. Particularly, organic-inorganic molecular ferroelectrics have received much interest recently because of their unique flexible structures, friendly environment, ease of synthesis, etc. Also, these hybrids show great flexibility in band-gap engineering. Here we report a new molecular halide, [C6H13N3SbBr5]n (1; C6H13N3 = 1-(3-aminopropyl)imidazole), which experiences a unique ferroelectric to paraelectric phase transition at around 230 K from space group P21 to P21/c. Significantly, compound 1 exhibits a narrow band gap with a value of 2.52 eV, large pronounced SHG-active, perfect rectangle hysteresis loops with a large spontaneous polarization of 6.86 µC/cm2. DSC (differential scanning calorimetry) and dielectric dependence on temperature tests and the volume change before and after the phase transition show that compound 1 is characterized by a second-order phase transition. These findings will contribute to the multifunctional materials field of organic-inorganic hybrids.

9.
Environ Sci Technol ; 55(1): 25-43, 2021 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-33319994

RESUMO

A critical review of the current state of knowledge of chemical emissions from indoor sources, partitioning among indoor compartments, and the ensuing indoor exposure leads to a proposal for a modular mechanistic framework for predicting human exposure to semivolatile organic compounds (SVOCs). Mechanistically consistent source emission categories include solid, soft, frequent contact, applied, sprayed, and high temperature sources. Environmental compartments are the gas phase, airborne particles, settled dust, indoor surfaces, and clothing. Identified research needs are the development of dynamic emission models for several of the source emission categories and of estimation strategies for critical model parameters. The modular structure of the framework facilitates subsequent inclusion of new knowledge, other chemical classes of indoor pollutants, and additional mechanistic processes relevant to human exposure indoors. The framework may serve as the foundation for developing an open-source community model to better support collaborative research and improve access for application by stakeholders. Combining exposure estimates derived using this framework with toxicity data for different end points and toxicokinetic mechanisms will accelerate chemical risk prioritization, advance effective chemical management decisions, and protect public health.


Assuntos
Poluentes Atmosféricos , Poluição do Ar em Ambientes Fechados , Compostos Orgânicos Voláteis , Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Poeira/análise , Humanos , Compostos Orgânicos/análise , Compostos Orgânicos Voláteis/análise
10.
Indoor Air ; 31(1): 156-169, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33439520

RESUMO

The indoor environmental quality in classrooms can largely affect children's daily exposure to indoor chemicals in schools. To date, there has not been a comprehensive study of the concentrations of semivolatile organic compounds (SVOCs) in French schools. Therefore, the French Observatory for Indoor Air Quality (OQAI) performed a field study of SVOCs in 308 nurseries and elementary schools between June 2013 and June 2017. The concentrations of 52 SVOCs, including phthalates, polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), synthetic musks, and pesticides, were measured in air and settled dust (40 SVOCs in both air and dust, 12 in either air or dust). The results showed that phthalates had the highest concentrations among the SVOCs in both the air and dust. Other SVOCs, including tributyl phosphate, fluorene, phenanthrene, gamma-hexachlorocyclohexane (gamma-HCH, lindane), galaxolide, and tonalide, also showed high concentrations in both the air and dust. Theoretical equations were developed to estimate the SVOC partitioning between the air and settled dust from either the octanol/air partition coefficient or the boiling point of the SVOCs. The regression constants of the equations were determined using the data set of the present study for phthalates and PAHs.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Poeira/análise , Instituições Acadêmicas , Compostos Orgânicos Voláteis/análise , Monitoramento Ambiental , Habitação , Humanos , Organofosfatos , Praguicidas/análise , Ácidos Ftálicos , Bifenilos Policlorados/análise , Hidrocarbonetos Policíclicos Aromáticos/análise
11.
Oral Dis ; 27(2): 226-239, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32649007

RESUMO

Oral cancer is among most common neoplasm of oral cavity; in many cases, it develops at the site of premalignant lesion. Areca nut has been identified as a carcinogen, which was proved to promote the inflammation level and contributes to oral malignancy. Chewing areca nut is the main cause of the premalignant disease oral submucous fibrosis (OSF). Bacterial alterations were suggested to be assonated with oral cancer progression. Therefore, the present study was carried out to determine the changes of microbiota in the mucosa along stage of development of oral cancer with areca nut chewing. 162 participants, reporting to department of oral medical center, were enrolled into the study which includes 45 patients each of OSF, 42 of oral cancer, 29 healthy controls (HC) with areca nut chewing, and 46 healthy controls (HC) never chewing areca nut. Oral swabbing of tongue dorsum, buccal mucosa, and gingiva was evaluated by MiSeq platform of the V3-V4 region of the 16S rRNA gene. These data revealed microbial changes that may mirror oral cancer progression and reflect clinical preconditions such as areca nut chewing. Consequently, revealing microbial changes in patients with oral squamous cell carcinomas and the premalignant disease oral submucous fibrosis (OSF) with areca nut chewing might improve our understanding of the pathobiology of the disease and help in the design of novel diagnostic and treatment strategies.


Assuntos
Microbiota , Neoplasias Bucais , Fibrose Oral Submucosa , Areca/efeitos adversos , Humanos , Mastigação , Neoplasias Bucais/etiologia , Fibrose Oral Submucosa/etiologia , RNA Ribossômico 16S/genética
12.
Molecules ; 26(4)2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33562613

RESUMO

Mastitis is a common disease in cows breeding. The milk quality will be significantly reduced with increased milk somatic cells, which often occurs in cows with mastitis. In this study, the influence of seasonal changes, age and lactation stages in the Dairy Herd Improvement (DHI) of cows was investigated. Then, the Dairy Herd Improvement (DHI) of cows with high somatic cell score (SCS) after melatonin treatment was systemically investigated. The results showed that melatonin significantly suppressed the milk somatic cell score under all of the tested conditions. The melatonin treatment also improved the milk nutritional value by reducing its fat but increasing its lactose and protein contents. The application of melatonin significantly improved the DHI. The beneficial effects of melatonin on DHI are likely attributed to the antioxidant and anti-inflammatory activities of melatonin.


Assuntos
Bovinos , Indústria de Laticínios , Melatonina/farmacologia , Animais , Bovinos/fisiologia , Contagem de Células , Feminino , Lactação/efeitos dos fármacos
13.
J Biol Chem ; 294(28): 10998-11010, 2019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31160337

RESUMO

The Y-box binding protein 1 (YB-1) is a member of the cold shock domain (CSD) protein family and is recognized as an oncogenic factor in several solid tumors. By binding to RNA, YB-1 participates in several steps of posttranscriptional regulation of gene expression, including mRNA splicing, stability, and translation; microRNA processing; and stress granule assembly. However, the mechanisms in YB-1-mediated regulation of RNAs are unclear. Previously, we used both systematic evolution of ligands by exponential enrichment (SELEX) and individual-nucleotide resolution UV cross-linking and immunoprecipitation coupled RNA-Seq (iCLIP-Seq) analyses, which defined the RNA-binding consensus sequence of YB-1 as CA(U/C)C. We also reported that through binding to its core motif CAUC in primary transcripts, YB-1 regulates the alternative splicing of a CD44 variable exon and the biogenesis of miR-29b-2 during both Drosha and Dicer steps. To elucidate the molecular basis of the YB-1-RNA interactions, we report high-resolution crystal structures of the YB-1 CSD in complex with different RNA oligos at 1.7 Å resolution. The structure revealed that CSD interacts with RNA mainly through π-π stacking interactions assembled by four highly conserved aromatic residues. Interestingly, YB-1 CSD forms a homodimer in solution, and we observed that two residues, Tyr-99 and Asp-105, at the dimer interface are important for YB-1 CSD dimerization. Substituting these two residues with Ala reduced CSD's RNA-binding activity and abrogated the splicing activation of YB-1 targets. The YB-1 CSD-RNA structures presented here at atomic resolution provide mechanistic insights into gene expression regulated by CSD-containing proteins.


Assuntos
Proteína 1 de Ligação a Y-Box/metabolismo , Proteína 1 de Ligação a Y-Box/ultraestrutura , Processamento Alternativo/fisiologia , Proteínas de Ligação a DNA/metabolismo , Éxons/genética , Éxons/fisiologia , Humanos , Ligação Proteica , RNA/metabolismo , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/metabolismo , Proteínas de Ligação a RNA/ultraestrutura , Proteína 1 de Ligação a Y-Box/genética
14.
Chemistry ; 26(26): 5887-5892, 2020 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-32040218

RESUMO

Smart multifunctional molecular ferroelectrics bearing high Curie temperatures and diverse excellent physical properties, such as second harmonic generation (SHG) responses, luminescence, and semiconductivity, among others, have significant applications but have seldom been documented. Herein, the rare-earth metals Nd and Pr are introduced into a simple molecular system (nBu4 N)3 [M(NO3 )x (SCN)y ] (nBu4 N= tetrabutyl ammonium, M=rare-earth metal, nBu=CH3 CH2 CH2 CH2 ), and two new multifunctional molecular ferroelectrics are obtained: (nBu4 N)3 [Nd(NO3 )4 (SCN)2 ] (1) and (nBu4 N)3 [Pr(NO3 )4 (SCN)2 ] (2). Their distinct heat and dielectric anomaly dependence on temperature verifies that compounds 1 and 2 experience high-temperature para-ferroelectric phase transitions at 408 and 413 K, respectively. Strikingly, both molecular ferroelectrics possess large spontaneous polarization with Ps values of 9.05 and 8.50 µC cm-2 , respectively, and are further characterized by the appearance of multiple intersecting non-180° domains and polarization switching behavior. In particular, compounds 1 and 2 show good stability with only a small decrease in SHG intensity after switching cycles, suggesting that they have great potential for application in nonlinear optical (NLO) switches. Simultaneously, the rare-earth compounds 1 and 2 present bright yellow-red and bright green fluorescence, respectively, at room temperature.

15.
Microb Cell Fact ; 19(1): 137, 2020 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-32653038

RESUMO

BACKGROUND: Zoonotic hepatitis E virus (HEV) infection emerged as a serious threat in the industrialized countries. The aim of this study is exploring a new approach for the control of zoonotic HEV in its main host (swine) through the design and development of an economically interesting chimeric vaccine against HEV and against a devastating swine infection: the foot-and-mouth disease virus (FMDV) infection. RESULTS: First, we adopted a computational approach for rational and effective screening of the different HEV-FMDV chimeric proteins. Next, we further expressed and purified the selected chimeric immunogens in Escherichia coli (E. coli) using molecular cloning techniques. Finally, we assessed the antigenicity and immunogenicity profiles of the chimeric vaccine candidates. Following this methodology, we designed and successfully produced an HEV-FMDV chimeric vaccine candidate (Seq 8-P222) that was highly over-expressed in E. coli as a soluble protein and could self-assemble into virus-like particles. Moreover, the vaccine candidate was thermo-stable and exhibited optimal antigenicity and immunogenicity properties. CONCLUSION: This study provides new insights into the vaccine development technology by using bioinformatics for the selection of the best candidates from larger sets prior to experimentation. It also presents the first HEV-FMDV chimeric protein produced in E. coli as a promising chimeric vaccine candidate that could participate in reducing the transmission of zoonotic HEV to humans while preventing the highly contagious foot-and-mouth disease in swine.


Assuntos
Febre Aftosa/prevenção & controle , Hepatite E , Proteínas Recombinantes de Fusão , Vacinas Virais , Animais , Hepatite E/prevenção & controle , Hepatite E/veterinária , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/imunologia , Suínos , Vacinas Virais/biossíntese , Vacinas Virais/imunologia
16.
BMC Genomics ; 20(1): 790, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31664890

RESUMO

BACKGROUND: The hepatitis E virus (HEV) is the causative pathogen of hepatitis E, a global public health concern. HEV comprises 8 genotypes with a wide host range and geographic distribution. This study aims to determine the genetic factors influencing the molecular adaptive changes of HEV open reading frames (ORFs) and estimate the HEV origin and evolutionary history. RESULTS: Sequences of HEV strains isolated between 1982 and 2017 were retrieved and multiple analyses were performed to determine overall codon usage patterns, effects of natural selection and/or mutation pressure and host influence on the evolution of HEV ORFs. Besides, Bayesian Coalescent Markov Chain Monte Carlo (MCMC) Analysis was performed to estimate the spatial-temporal evolution of HEV. The results indicated an A/C nucleotide bias and ORF-dependent codon usage bias affected mainly by natural selection. The adaptation of HEV ORFs to their hosts was also ORF-dependent, with ORF1 and ORF2 sharing an almost similar adaptation profile to the different hosts. The discriminant analysis based on the adaptation index suggested that ORF1 and ORF3 could play a pivotal role in viral host tropism. CONCLUSION: In this study, we estimate that the common ancestor of the modern HEV strains emerged ~ 6000 years ago, in the period following the domestication of pigs. Then, natural selection played the major role in the evolution of the codon usage of HEV ORFs. The significant adaptation of ORF1 of genotype 1 to humans, makes ORF1 an evolutionary indicator of HEV host speciation, and could explain the epidemic character of genotype 1 strains in humans.


Assuntos
Evolução Molecular , Vírus da Hepatite E/genética , Códon , Vírus da Hepatite E/classificação , Mutação , Nucleotídeos/análise , Fases de Leitura Aberta , Filogenia , Seleção Genética , Proteínas Virais/genética
17.
J Am Chem Soc ; 141(23): 9134-9139, 2019 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-31131600

RESUMO

The flexible organic amine cations on the interfaces of two-dimensional (2D) hybrid organic-inorganic perovskite nanosheets could form relaxed structures, which would lead to exotic optoelectronic properties but are hard to understand. Here, the unusual interfacial relaxation of nanosheets exfoliated from an orthorhombic 2D lead halide perovskite, [(C6H5CH2NH3)2]PbCl4, is interrogated via ultrafast second-harmonic generation (SHG) spectroscopy. The in-plane SHG intensity anisotropy of these nanosheets is found to decrease with reducing layer thickness. Combined first-principles calculations and Monte Carlo simulations reveal that the induced second-order polarization arises primarily from the (C6H5CH2NH3)+ cations; and these organic amine cations form significantly reorganized conformations with decreasing nanosheet thickness due to weakened van der Waals interactions. Because the orientations of organic components at the interface determine their electric properties and specifically the dipolar susceptibility, the resulting structure leads to striking changes in the SHG properties.

18.
Inorg Chem ; 58(15): 9733-9737, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31283197

RESUMO

The hybrid organic-inorganic materials have received extraordinary attention from the academic community not only because of their natural chemical tunability but also because of their potential in producing exotic physical properties. However, these characteristics are usually caused by the phase transition of materials under changing of external terms, and it is crucial to fully understand their origins. Here, we research an unusual phase transition near room temperature between two ordered phases in a one-dimensional (1D) hybrid organic-inorganic material of Sb|||-based [(CH2)3NH2S]2SbCl5 (1). This phase transition is caused by collective actions, including the primary variation in the bonds of inorganic five-coordinated tetragonal pyramids, displacement and rotation of organic and inorganic components, along with concurrent hydrogen bonds transformation. Afterward, we observe a significant dielectric anomaly at low frequencies between low and high temperatures. This attributed to the fact that two phases coexist with the lessening temperature, which means that a small number of high-temperature features remained but did not occur during the heating process. These findings offer an avenue for inventing a fresh phase transition and dielectric switch hybrid materials, which further open up the prospect for their practical application.

19.
Indoor Air ; 29(5): 704-726, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31220370

RESUMO

Indoor air quality (IAQ), as determined by the concentrations of indoor air pollutants, can be predicted using either physically based mechanistic models or statistical models that are driven by measured data. In comparison with mechanistic models mostly used in unoccupied or scenario-based environments, statistical models have great potential to explore IAQ captured in large measurement campaigns or in real occupied environments. The present study carried out the first literature review of the use of statistical models to predict IAQ. The most commonly used statistical modeling methods were reviewed and their strengths and weaknesses discussed. Thirty-seven publications, in which statistical models were applied to predict IAQ, were identified. These studies were all published in the past decade, indicating the emergence of the awareness and application of machine learning and statistical modeling in the field of IAQ. The concentrations of indoor particulate matter (PM2.5 and PM10 ) were the most frequently studied parameters, followed by carbon dioxide and radon. The most popular statistical models applied to IAQ were artificial neural networks, multiple linear regression, partial least squares, and decision trees.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Árvores de Decisões , Aprendizado de Máquina , Redes Neurais de Computação , Análise de Regressão , Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Humanos , Modelos Estatísticos
20.
Biomed Microdevices ; 20(3): 80, 2018 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-30191323

RESUMO

3D models of tumours have emerged as an advanced technique in pharmacology and tumour cell biology, in particular for studying malignant tumours such as glioblastoma multiforme (GBM). Herein, we developed a 3D GBM model on a detachably assembled microfluidic device, which could be used to study GBM aggressiveness and for anti-GBM drug testing. Fundamental characteristics of the GBM microenvironment in terms of 3D tissue organisation, extracellular matrices and blood flow were reproduced in vitro by serial manipulations in the integrated microfluidic device, including GBM spheroid self-assembly, embedding in a collagen matrix, and continuous perfusion culture, respectively. We could realize multiple spheroids parallel manipulation, whilst, compartmentalized culture, in a highly flexible manner. This method facilitated investigations into the viability, proliferation, invasiveness and phenotype transition of GBM in a 3D microenvironment and under continuous stimulation by drugs. Anti-invasion effect of resveratrol, a naturally isolated polyphenol, was innovatively evaluated using this in vitro 3D GBM model. Temozolomide and the combination of resveratrol and temozolomide were also evaluated as control. This scalable model enables research into GBM in a more physiologically relevant microenvironment, which renders it promising for use in translational or personalised medicine to examine the impact of, or identify combinations of, therapeutic agents.


Assuntos
Avaliação de Medicamentos , Glioblastoma/tratamento farmacológico , Dispositivos Lab-On-A-Chip , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular/efeitos dos fármacos , Matriz Extracelular/química , Regulação Neoplásica da Expressão Gênica , Humanos , Esferoides Celulares , Microambiente Tumoral
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA