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1.
Molecules ; 28(13)2023 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-37446843

RESUMO

Alginate/lignin is a synthetic polymer rich in biological activity and is of great interest. Alginate is extracted from seaweed and lignin is extracted from corn stalks and leaves. In this paper, antioxidant activities of alginate/lignin were evaluated, such as total antioxidant activity, reducing power activity, DPPH free radical scavenging activity, and α-glucosidase inhibition activity. Anticancer activity was evaluated in three cell lines (Hep G2, MCF-7, and NCI H460) and fibroblast. Physico-chemistry characteristics of alginate/lignin were determined through FTIR, DSC, SEM_EDS, SEM_EDS mapping, XRD, XRF, and 1H-NMR. The acute toxicity of alginate/lignin was studied on Swiss albino mice. The results demonstrated that alginate/lignin possessed antioxidant activity, such as the total antioxidant activity, and reducing power activity, especially the α-glucosidase inhibition activity, and had no free radical scavenging activity. Alginate/lignin was not typical in cancer cell lines. Alginate/lignin existed in a thermally stable and regular spherical shape in the investigated thermal region. Six metals, three non-metals, and nineteen oxides were detected in alginate/lignin. Some specific functional groups of alginate and lignin did not exist in alginate/lignin crystal. Elements, such as C, O, Na, and S were popular in the alginate/lignin structure. LD0 and LD100 of alginate/lignin in mice were 3.91 g/kg and 9.77 g/kg, respectively. Alginate/lignin has potential for applications in pharmaceutical materials, functional foods, and supporting diabetes treatment.


Assuntos
Antioxidantes , Alga Marinha , Animais , Camundongos , Antioxidantes/farmacologia , Antioxidantes/química , Lignina/farmacologia , Alginatos/farmacologia , Alginatos/química , alfa-Glucosidases , Alga Marinha/química
2.
Langmuir ; 38(13): 4138-4146, 2022 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-35324210

RESUMO

Nitric oxide (NO) removal by photocatalytic oxidation over g-C3N4 has achieved more efficient results. However, there is a concern about the high NO-to-NO2 conversion yield of products, which is not suitable for the photocatalytic NO reaction. In this study, we modify g-C3N4 by WO3 nanoplates for the first time for photocatalytic NO oxidation over a WO3/g-C3N4 composite to enhance the green product selectivity under atmospheric conditions. The results indicate that the photocatalytic efficiency for NO removal by the WO3/g-C3N4 composite is drastically improved and achieves 52.5%, which is approximately 2.1 times higher than that of pure g-C3N4. Significantly, the green product (NO3-) selectivity of the WO3/g-C3N4 composite is 8.7 times higher than that of pure g-C3N4, and the selectivity remained high even after five cycles of photocatalytic tests. We also conclude that the enhanced green product selectivity of photocatalytic NO oxidation by the WO3/g-C3N4 composite is due to the separation and acceleration of the photogenerated charges of the WO3/g-C3N4 S-scheme heterojunction.

3.
J Water Health ; 20(3): 491-504, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35350002

RESUMO

Water quality for the surface water along the Saigon River in Ho Chi Minh City was assessed for four groups of water samples collected at the agricultural, industrial, residential, and less impacted areas. A variety of parameters indicating water quality including physicochemical parameters, nutrients, heavy metals, and antibiotic residues were measured for both the rainy and dry seasons, two main tropical seasons in HCM City using the standard methods. The results showed that the river water in the rainy season was detected with significantly higher values of turbidity, BOD5, PO4-P, NH4-N, NO3-N; and lower values of pH, temperature, conductivity, DO, salinity, Cu, Zn, As, Ni, Hg compared to that in the dry season. Sulfamethoxazole and trimethoprim were highly detected in the industrial areas compared to the agricultural and residential areas. Multivariate analyses suggested that the industrial and residential activities were more important contributors to the pollution of the Saigon River than the agricultural activities in HCM City.


Assuntos
Rios , Qualidade da Água , Efeitos Antropogênicos , Cidades , Monitoramento Ambiental , Rios/química
4.
Molecules ; 27(4)2022 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-35209056

RESUMO

Carrageenan is an anionic sulfated polysaccharide that accounts for a high content of red seaweed Eucheuma gelatinae. This paper focused on the extraction, optimization, and evaluation of antioxidant activity, rheology characteristics, and physic-chemistry characterization of ß-carrageenan from Eucheuma gelatinae. The extraction and the optimization of ß-carrageenan were by the maceration-stirred method and the experimental model of Box-Behken. Antioxidant activity was evaluated to be the total antioxidant activity and reducing power activity. The rheology characteristics of carrageenan were measured to be gel strength and viscosity. Physic-chemistry characterization was determined, including the molecular weight, sugar composition, function groups, and crystal structure, through GCP, GC-FID, FTIR, and XRD. The results showed that carrageenan possessed antioxidant activity, had intrinsic viscosity and gel strength, corresponding to 263.02 cps and 487.5 g/cm2, respectively. Antioxidant carrageenan is composed of rhamnose, mannose, glucose, fucose, and xylose, with two molecular weight fractions of 2.635 × 106 and 2.58 × 106 g/mol, respectively. Antioxidant carrageenan did not exist in the crystal. The optimization condition of antioxidant carrageenan extraction was done at 82.35 °C for 115.35 min with a solvent-to-algae ratio of 36.42 (v/w). At the optimization condition, the extraction efficiency of carrageenan was predicted to be 87.56 ± 5.61 (%), the total antioxidant activity and reducing power activity were predicted to 71.95 ± 5.32 (mg ascorbic acid equivalent/g DW) and 89.84 ± 5.84 (mg FeSO4 equivalent/g DW), respectively. Purity carrageenan content got the highest value at 42.68 ± 2.37 (%, DW). Antioxidant carrageenan from Eucheuma gelatinae is of potential use in food and pharmaceuticals.


Assuntos
Antioxidantes/química , Antioxidantes/farmacologia , Carragenina/química , Carragenina/farmacologia , Rodófitas/química , Algoritmos , Antioxidantes/isolamento & purificação , Carragenina/isolamento & purificação , Fracionamento Químico/métodos , Fenômenos Químicos , Concentração de Íons de Hidrogênio , Modelos Químicos , Reologia
5.
Ecotoxicol Environ Saf ; 212: 111971, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33513480

RESUMO

In this study, an AhR-responsive reporter-gene cell-based bioassay CALUX was used to assess the biological potency of dioxins and dioxin-like PCBs (dl-PCBs) in top soil samples collected from a former airbase (A-So) and remote regions from urban and agricultural areas in Thua Thien Hue, Vietnam. In top soil collected from A-So airbase, Bioanalytical EQuivalent (BEQ) concentrations of up to 2700 pg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) per g dry weight (pg BEQ-TCDD g-1 dw) were assessed. Interestingly, while BEQ values for dl-PCBs were found to be up to 13 pg BEQ-TCDD g-1 dw, the dl-PCB activity was not detected in all the hotspot sample extracts. In contrasts, BEQ values for dioxin like compounds from remote regions were much lower and occasionally below the quantification limits of the method. The BEQ activities obtained in this study have a similar trend to the WHO-TEQ results for the samples collected in the A-So airbase. However, BEQ values were higher than those of TEQ, probably reflecting the presence of additional AhR ligands and/or possible non-additive interactions in the sample mixture. This study confirms that after more than 60 years, a strong residual pollution of PCDD/Fs remains on this former air base following the use and storage of Agent Orange during the Vietnam War, raising a health risk for populations exposed in this area because livestock animals graze there.


Assuntos
Agente Laranja , Monitoramento Ambiental , Poluentes do Solo/análise , Animais , Benzofuranos , Bioensaio/métodos , Dibenzofuranos , Dioxinas/toxicidade , Genes Reporter , Bifenilos Policlorados/análise , Dibenzodioxinas Policloradas , Solo , Poluentes do Solo/toxicidade , Vietnã
6.
Growth Factors ; 38(5-6): 282-290, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-34415815

RESUMO

Fibroblast growth factor 2 (FGF-2) is a multifunctional protein that has major roles in wound healing, tissue repair, and regeneration. This therapeutic protein is widely used for burn treatment because it can stimulate cell proliferation and differentiation, angiogenesis, and extracellular matrix remodeling. In this study, we developed a simple method using a controlled heated brass rod to create a homogenous third-degree burn murine model and evaluated the treatment using recombinant human FGF-2 (rhFGF-2). The results indicated that the wound area was 0.83 ± 0.05 cm2 and wound depth was 573.42 ± 147.82 µm. Mice treated with rhFGF-2 showed higher rates of wound closure, granulation tissue formation, angiogenesis, and re-epithelialization than that of phosphate-buffered saline (PBS)-treated group. In conclusion, our lab-made rhFGF-2 could be a potentially therapeutic protein for burn treatment as well as a bioequivalent drug for other commercial applications using FGF-2.


Assuntos
Queimaduras , Fator 2 de Crescimento de Fibroblastos , Animais , Queimaduras/tratamento farmacológico , Proliferação de Células , Humanos , Camundongos , Neovascularização Patológica , Cicatrização
7.
J Environ Sci Health B ; 55(5): 417-428, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31880201

RESUMO

A GC-MS/MS method with low solvent consumption and easy operation was developed to simultaneously determine ten new-generation pesticides, namely fenobucarb, acetochlor, pretilachlor, fipronil, trifloxystrobin, fluazifop-p-butyl, isoprothiolane, tebuconazole, cypermethrin and difenoconazole in leafy vegetables. Influences from ultrasonic sample extraction and the clean-up steps to reduce matrix effects were investigated. Under suitable conditions, good linearity (deviation of back calculated concentration from true concentration lower than 20%) was achieved for all studied pesticides; the method detection limits (MDLs) ranged from 1.4 to 3.6 ng g-1 wet weight. For mustard green and green onion the method yielded good recoveries at two spiking levels (201 and 100 ng g-1) ranging from 80% to 111% (n = 5). The repeatability, expressed as relative standard deviation (RSD), was lower than 11% (n = 5). The method was successfully used to quantify pesticide residues in 207 vegetable samples (green onions, mustard greens, and lettuce) collected in Thua Thien Hue and Quang Binh Provinces, Central Vietnam. The insecticide cypermethrin was found at critical levels in 98% of the vegetable samples. Green onions had high pesticide residues with a significant number of samples containing pesticides at concentrations exceeding the maximum residue levels (MRLs).


Assuntos
Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Praguicidas/análise , Verduras/química , Limite de Detecção , Resíduos de Praguicidas/análise , Solventes/química , Espectrometria de Massas em Tandem/métodos , Vietnã
8.
J Nanosci Nanotechnol ; 19(6): 3293-3300, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30744756

RESUMO

Recently, drug delivery using natural and biodegradable nanoparticles has attracted huge attention. This study focused to deliver an anti-cancer and anti-inflammatory drug Ginsenoside Rb1 through chitosan-Alginate nanocomposite film prepared by solution method. Ginsenoside Rb1 is a dammaran saponin group, which is extracted from an herbaceous plant Panax notoginseng. Ginsenoside loaded alginate-chitosan nanocomposite films were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) methods. The FTIR spectra of alginate/chitosan/ginsenoside Rb1 nanocomposite films show that chitosan, alginate, and ginsenoside Rb1 are linked through the hydrogen bonding and dipolar-dipolar interactions. The FESEM image indicates that the chitosan and ginsenoside Rb1 dispersed well in the alginate matrix. The DSC diagrams display that melting temperature of alginate/chitosan/ginsenoside Rb1 nanocomposite films higher than that of chitosan and lower than that of alginate. It means that alginate and chitosan interact together. Investigation of the ginsenoside Rb1 release from alginate/chitosan/ginsenoside Rb1 nanocomposite films at different pH solutions and different ginsenoside Rb1 content has been carried out by ultraviolet-visible spectroscopy method. The rate of drug release is proportional to the increase in pH solution and inversely proportional to the content of loaded ginsenoside Rb1. The Rb1 release process includes two stages: burst release in the first 10 hours, then constant release afterwards. The suitable ratio of alginate/chitosan to prepare the alginate/chitosan/ginsenoside Rb1 nanocomposite films for further investigations was found out to be 8:2. Ginsenoside Rb1 release process from alginate/chitosan/ginsenoside Rb1 nanocomposite films was believed to be first-order kinetics in the first stage, and then the Rb1 release complies with Higuchi kinetic model in the slow release stage. This study demonstrated the novel synthesis methodology to design drug delivery system based on ginsenoside Rb1 loaded to chitosan/alginate nanocomposite films.


Assuntos
Quitosana , Ginsenosídeos , Nanocompostos , Alginatos , Sistemas de Liberação de Medicamentos , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Proc Natl Acad Sci U S A ; 113(34): 9475-9, 2016 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-27503886

RESUMO

Spontaneous symmetry breaking occurs in a physical system whenever the ground state does not share the symmetry of the underlying theory, e.g., the Hamiltonian. This mechanism gives rise to massless Nambu-Goldstone modes and massive Anderson-Higgs modes. These modes provide a fundamental understanding of matter in the Universe and appear as collective phase or amplitude excitations of an order parameter in a many-body system. The amplitude excitation plays a crucial role in determining the critical exponents governing universal nonequilibrium dynamics in the Kibble-Zurek mechanism (KZM). Here, we characterize the amplitude excitations in a spin-1 condensate and measure the energy gap for different phases of the quantum phase transition. At the quantum critical point of the transition, finite-size effects lead to a nonzero gap. Our measurements are consistent with this prediction, and furthermore, we demonstrate an adiabatic quench through the phase transition, which is forbidden at the mean field level. This work paves the way toward generating entanglement through an adiabatic phase transition.

10.
Phys Rev Lett ; 120(8): 080602, 2018 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-29542995

RESUMO

Nonequilibrium processes of small systems such as molecular machines are ubiquitous in biology, chemistry, and physics but are often challenging to comprehend. In the past two decades, several exact thermodynamic relations of nonequilibrium processes, collectively known as fluctuation theorems, have been discovered and provided critical insights. These fluctuation theorems are generalizations of the second law and can be unified by a differential fluctuation theorem. Here we perform the first experimental test of the differential fluctuation theorem using an optically levitated nanosphere in both underdamped and overdamped regimes and in both spatial and velocity spaces. We also test several theorems that can be obtained from it directly, including a generalized Jarzynski equality that is valid for arbitrary initial states, and the Hummer-Szabo relation. Our study experimentally verifies these fundamental theorems and initiates the experimental study of stochastic energetics with the instantaneous velocity measurement.

11.
Phys Rev Lett ; 121(3): 033603, 2018 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-30085795

RESUMO

Levitated optomechanics has great potential in precision measurements, thermodynamics, macroscopic quantum mechanics, and quantum sensing. Here we synthesize and optically levitate silica nanodumbbells in high vacuum. With a linearly polarized laser, we observe the torsional vibration of an optically levitated nanodumbbell. This levitated nanodumbbell torsion balance is a novel analog of the Cavendish torsion balance, and provides rare opportunities to observe the Casimir torque and probe the quantum nature of gravity as proposed recently. With a circularly polarized laser, we drive a 170-nm-diameter nanodumbbell to rotate beyond 1 GHz, which is the fastest nanomechanical rotor realized to date. Smaller silica nanodumbbells can sustain higher rotation frequencies. Such ultrafast rotation may be used to study material properties and probe vacuum friction.

12.
J Nanosci Nanotechnol ; 18(5): 3624-3630, 2018 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-29442876

RESUMO

In order to improve dispersiveness of nanosilica in polymer matrix, surface organo-modification of nanosilica is necessary. This work reveals silica nanoparticles modified by titanate coupling agent isopropyltri (dioctylphosphate) titanate (KR12) in toluene solvent. Effect of reaction temperature, reaction time and reactant ratio on grafting efficiency have been studied by Thermogravimetric Analysis (TGA). The obtained results exhibit the grafted percentage of titanate coupling agent KR-12 on the surface of nanosilica increased quickly from 4.97 to 13.11 wt.% as increasing the content of KR-12 from 5 to 15 wt.% and raise slower from 13.21 to 13.43 wt.% as content of KR-12 in the range of 30 to 45 wt.%, respectively. The KR-12 content and grafting reaction time affect significantly on the grafting efficiency while temperature of grafting reaction is negative to the grafting efficiency. The results of analysis related to Infrared Spectroscopy and Energy-Dispersive X-ray spectroscopy (EDS) displayed titanate coupling agent KR-12 have been covalently bonded to surface of the nanosilica. The Transmission Electron Microscopy (TEM) images and size distribution indicated that after organic modification, nanosilica particles had average size about 86 nm and the agglomeration of nanoparticles decreased significantly. The obtained results showed that surface treatment of nanosilica with titanate coupling agent KR-12 was successful.

13.
J Nanosci Nanotechnol ; 18(7): 4963-4970, 2018 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-29442680

RESUMO

This paper presents the tensile, thermal, dielectric and morphological properties of composites based on polyoxymethylene (POM) and nanosilica (NS) prepared by melt mixing method at 190 °C. Based on the torque readings, the processing of POM/NS composites were found to be easier in comparison to only POM. The FT-IR spectra analysis of the POM/NS nanocomposites showed the presence of peak at approximately 910 cm-1, attributed to the Si-O and C-O groups in NS and POM on the POM/NS nanocomposite. The absorption at these peaks increased on gradually increasing the content of NS. Tensile property testing (tensile strength, elongation at break, and Young's modulus) indicated that the tensile strength of POM/NS nanocomposites increases as the NS content increases from 0.5 wt.% to 1.5 wt.%, and sharply dropped when the NS content was more than 2 wt.%. A similar trend was observed for Young's modulus and elongation at break of the nanocomposites. The DSC analysis of the nanocomposites showed that the melting temperature (Tm) of POM/NC composites increased in the presence of low weight % of NS which can be attributed to the interaction between POM and NS leading to the rising crystallinity of all nanocomposites. POM/NS have a slightly higher temperature resistance as confirmed from the TGA analysis and POM/NS 1.5 wt.% had the maximum degradation temperature (Tmax) value and consequently the lowest weight loss. The dielectric constant of the nanocomposites increased from 3.26 to 3.56, while the dielectric loss tangent and volume resistivity were dropped, corresponding to the NS content from 0.5 to 2 wt.%. The SEM images of POM/NS nanocomposites demonstrated that the NS particles were dispersed relatively regularly into POM with a size in the range of 100 to 500 nm. They were dispersed more regularly into the polymer matrix at 1.5 wt.% NS. Based on the obtained results, the suitable NS content for the preparation of the POM/NS nanocomposites was found to be 1.5 wt.%.

14.
J Nanosci Nanotechnol ; 18(4): 2830-2837, 2018 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-29442963

RESUMO

In this study, carbon nanotubes (CNTs)/ZnO composites had been prepared using the sol-gel method and then incorporated into an epoxy resin for reinforcement of mechanical and electrical properties. Fourier Transform Infrared (FTIR), X-ray diffraction (XRD) Field Emission Scanning Electron Microscope (FE-SEM) analyses show that the ZnO nanoparticles deposited on CNTs were crystallized in a hexagonal wurtzite structure. Average particle size of ZnO deposited on the CNT was about 8 nm. The mechanical and dielectric properties of epoxy containing CNTs/ZnO were investigated in comparison to epoxy resin and epoxy resin containing only CNT or ZnO nanoparticles. The results indicated that tensile strength and elongation at break of the nanocomposite were substantially improved with the presence of CNTs/ZnO at the equal volume. The DSC analysis associate with the dielectric results shows that the behavior of epoxy/CNTs/ZnO is identical to epoxy/ZnO composite, and the CNTs is essential to the distributed arrangement of ZnO in the epoxy resin.

15.
J Nanosci Nanotechnol ; 18(4): 2294-2303, 2018 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-29442895

RESUMO

This paper presents the results of zeta potential, water contact angle, atomic force microscopy image, in vitro solubility, and content of heavy metals in polylactic acid (PLA)/chitosan (CS) nanoparticles loading nifedipine. In addition, the In Vivo test of the PLA/CS nanoparticles loading nifedipine in the mice is also one of highlights of this work. The Zeta potential result shows that the charged surface of the PLA/CS nanoparticles loading nifedipine is neutral, negative or complex depending on nifedipine content. Nifedipine plays a role in increase of hydrophobic property, swelling degree and regular surface as well as decrease of surface rough of the nanoparticles. The PLA/CS/nifedipine nanoparticles are dissolved in the solutions with pH 6.8, pH 4.5 and pH 1.2. The In Vivo test of PLA/CS nanoparticles loading nifedipine on mice was evaluated by the change in diastolic pressure, systolic pressure, arterial pressure and heart rate. The obtained results confirm that the PLA/CS nanoparticles loading nifedipine is suitable to apply in the treatment of hypertension patients lately.


Assuntos
Bloqueadores dos Canais de Cálcio/administração & dosagem , Quitosana/química , Nanopartículas , Nifedipino/administração & dosagem , Poliésteres/química , Animais , Bloqueadores dos Canais de Cálcio/farmacocinética , Humanos , Camundongos , Nifedipino/farmacocinética , Polímeros
16.
J Indian Prosthodont Soc ; 18(3): 212-218, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30111909

RESUMO

AIM: The aim of this study was to compare the adhesion of glass-ceramic overlays to tooth structure, under the effect of shear forces, using different bonding systems. MATERIALS AND METHODS: Thirty healthy lower third molars were selected and randomly allocated into three groups (n = 10). Group 1: overlays bonded to tooth structure using Panavia V5 with immediate dentin sealing (IDS); Group 2: overlays bonded using Panavia V5 without IDS; and Group 3: overlays bonded using heated composite combined with a bonding agent with IDS. All the restorations were made of glass-ceramic (Suprinity, Vita). The restored teeth were then stored in distilled water for 7 days and at room temperature. Shear forces were applied using a universal testing machine. Load and displacement were recorded at intervals of 0.1 s. A statistical analysis was used to compare the groups. RESULTS: The mean resistance to fractures ± standard deviation obtained for the Groups 1, 2, and 3 was, respectively, 15.7440 ± 2.13, 12.0750 ± 1.41, and 8.33364 ± 2.85 MPa. The analysis of variance was highly significant (P < 0.001) allowing us to reject the null hypothesis of equality between the three groups. Comparisons between pairs also provided significant results. CONCLUSION: Bonding using Panavia V5 with IDS showed a better resistance to shear forces when compared to other bonding techniques. The application of IDS increased the adhesion.

17.
J Struct Biol ; 197(2): 123-134, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27725257

RESUMO

Focused Ion Beam milling combined with Scanning Electron Microscopy is a powerful tool to determine the 3-D organization of whole cells and tissue at an isotropic resolution of 3-5nm. This opens the possibility to quantify several cellular parameters and to provide detailed phenotypic information in normal or disease states. Here we describe Biocomputing methods to extract in an automated way characteristic features of mouse rod photoreceptor nuclei such as the shape and the volume of the nucleus; the proportion of heterochromatin; the number, density and distribution of nuclear pore complexes (NPC). Values obtained on five nuclei show that the number of NPC (348±8) is the most conserved feature. Nuclei in higher eukaryotes show large variations in size and rod nuclei are amongst the smallest reported (32±3µm3). Despite large species- and cell-type-specific variations in size, the density of NPC (about 15/µm2) is highly conserved.


Assuntos
Substituição ao Congelamento/métodos , Microscopia Eletrônica de Varredura/métodos , Retina/ultraestrutura , Animais , Heterocromatina/ultraestrutura , Camundongos , Complexo de Proteínas Formadoras de Poros Nucleares/ultraestrutura
18.
Phys Rev Lett ; 117(12): 123604, 2016 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-27689273

RESUMO

An optically levitated nanoparticle in vacuum is a paradigm optomechanical system for sensing and studying macroscopic quantum mechanics. While its center-of-mass motion has been investigated intensively, its torsional vibration has only been studied theoretically in limited cases. Here we report the first experimental observation of the torsional vibration of an optically levitated nonspherical nanoparticle in vacuum. We achieve this by utilizing the coupling between the spin angular momentum of photons and the torsional vibration of a nonspherical nanoparticle whose polarizability is a tensor. The torsional vibration frequency can be 1 order of magnitude higher than its center-of-mass motion frequency, which is promising for ground state cooling. We propose a simple yet novel scheme to achieve ground state cooling of its torsional vibration with a linearly polarized Gaussian cavity mode. A levitated nonspherical nanoparticle in vacuum will also be an ultrasensitive nanoscale torsion balance with a torque detection sensitivity on the order of 10^{-29} N m/sqrt[Hz] under realistic conditions.

19.
J Nanosci Nanotechnol ; 15(5): 3887-92, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-26505019

RESUMO

We report on the fabrication and the electrochemical behavior of TiN film on the 316L stainless steel (316LSS) material in simulated body fluid (SBF) solution for implant application. The characterization results indicate that the coated TiN is completely crystalline with (111) crystal orientation. Electrochemical results of 316LSS and TiN/316LSS material after 21 days of immersion in SBF show that the durability of the TiN/316LSS is much higher than that of 316LSS, which registers a very low corrosion current density (about tens of nA cm(-2)). The formation of hydroxyapatite on the surface of the TiN/316LSS is also confirmed by SEM, EDX, X-ray and IR spectroscopy.


Assuntos
Líquidos Corporais/química , Modelos Biológicos , Aço Inoxidável/química , Titânio/química , Durapatita/química , Durapatita/metabolismo , Técnicas Eletroquímicas , Nanotecnologia , Próteses e Implantes
20.
J Nanosci Nanotechnol ; 15(12): 9585-90, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26682382

RESUMO

Poly-lactic acid (PLA) has been widely applied in the medical field (in biomedicines such as medical capsules, surgical sutures and suture wounds) owing to its high biodegradability, good biocompatibility and ability to be dissolved in common solvents. Chitosan (CS) is an abundant polysaccharide and a cationic polyelectrolyte present in nature. In this study, the combination of PLA and CS has been used to form PLA/CS nanocomposites having the advantages of both the original components. To enhance the dispersibility and compatibility between PLA and CS in the PLA/CS nanocomposites, polycaprolactone (PCL) is added as a compatibilizer. The Fourier Transform Infrared spectroscopies prove the existence of the interactions of PCL with PLA and CS. A more regular dispersion of CS of 200-400 nm particle size, is observed in the PLA matrix of the PLA/CS nanocomposites containing PCL, through the Field Emission Scanning Electron Microscopy images. The appearance of one glass transition temperature (T(g)) value of PLA/CS/PCL nanocomposites occuring between the T(g) values of PLA and CS in DSC diagrams confirms the improvement in the compatibility between PLA and CS, due to the presence of PCL. The TGA result shows that PCL plays an important role in enhancing the thermal stability of PLA/CS/PCL nanocomposites. The hydrolysis of PLA/CS/PCL nanocomposites in alkaline and phosphate buffer solutions was investigated. The obtained results show that the PLA/CS/PCL nanocomposites have slower hydrolysis ability than the PLA/CS composites.


Assuntos
Quitosana/química , Nanocompostos/química , Poliésteres/química , Hidrólise , Microscopia Eletrônica de Varredura
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