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1.
Adv Mater ; 31(25): e1807849, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31058371

RESUMO

Artificially structured thermal metamaterials provide an unprecedented possibility of molding heat flow that is drastically distinct from the conventional heat diffusion in naturally conductive materials. The Laplacian nature of heat conduction makes the transformation thermotics, as a design principle for thermal metadevices, compatible with transformation optics. Various functional thermal devices, such as thermal cloaks, concentrators, and rotators, have been successfully demonstrated. How far can it possible go beyond just realizing a heat-distribution function in a thermal metadevice? Herein, the concept of encrypted thermal printing is proposed and experimentally validated, which could conceal encrypted information under natural light and present static or dynamic messages in an infrared image. Regionalization transformation is developed for structuring thermal metamaterial-strokes as infrared signatures, enabling letters of the alphabet to be written, paintings to be drawn, movies to be made, and information to be displayed. This strategy successfully demonstrates an extreme level of manipulation of heat flow for encryption, illusions, and messaging.

2.
ACS Appl Mater Interfaces ; 11(21): 19623-19630, 2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-31056914

RESUMO

Enhancing the light extraction efficiency is a prevalent but vital challenge for most solid-state lighting technologies, especially for deep ultraviolet light-emitting diodes (DUV-LEDs). In this paper, inspired by the microstructure of the butterfly's eye, we propose and fabricate a flexible fluoropolymer film (FFP film) to tackle this issue for all-mode, full-wavelength light extraction enhancement for most solid-state lighting technologies compatibly. The experimental results demonstrate that compared with one mounted with a smooth FFP film, the light output power of DUV-LED is enhanced up to 26.7% by mounting the FFP film with 325 nm radius nanocones at a driving current of 200 mA. Importantly, thanks to the super-flexible feature of the FFP film, it can both cover the top surface and sidewalls of the DUV-LED chip, leading to the improvement of transverse electric and transverse magnetic mode light extraction by 20.5 and 21.8%, respectively. Finite element analysis (FEA) simulations of the electric field distribution of DUV-LEDs with the FFP film reveal the underlying physics. The present strategy is proposed from the view of the packaging level, which is cost-effective, able to be manufactured at a large scale, and compatible with the solid-state lighting technologies.

3.
Soft Matter ; 15(21): 4320-4325, 2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-31070662

RESUMO

Droplet impingement on heated surfaces has been investigated by varying the surface textures, temperature, and droplet properties with demonstration of various phenomenological behaviors, such as evaporation, boiling, splashing, and Leidenfrost bouncing. However, the ambient pressure dependence has not been well explored, especially for ambient pressures lower than 5 kPa. By examining the ambient pressure (from 0.2 to 20 kPa) and surface temperature (from 20 to 200 °C) simultaneously, we found a novel explosive bouncing behavior which is different from Leidenfrost bouncing and only occurs at extremely low ambient pressure (≤6 kPa). Through experimental validation and mechanical analysis, we found that the explosive bouncing is caused by the dramatic explosion of the local vapor bubble and reducing the ambient pressure benefits the formation and explosion of the vapor bubble.

4.
Opt Express ; 26(13): 16442-16455, 2018 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-30119475

RESUMO

The behaviors of the light propagation in the phosphor play a vital role in determining the optical performance of the phosphor-converted light-emitting diodes (pc-LEDs). In this paper, we presented a general model based on the radiative transfer equation integrated with fluorescence (FRTE) to describe the overall light propagating properties in the phosphor layer in terms of light absorption, strong forward scattering, and fluorescence. The model was established by accounting for general boundary conditions including the LED Lambertian incidence, the diffuse reflection at the substrate/reflector, and the Fresnel reflection at the phosphor-air interface. The spectral element method (SEM) was extended to numerically solve FRTE. The radiant intensity at any location and direction of blue and yellow light was iteratively calculated, in which case the angular properties could be further evaluated. The model was validated by comparing the light extraction efficiency (LEE) and angular correlated color temperature (CCT) calculated by the presented model with the experimental results. Good agreements were achieved between model predictions and measurements with the corresponding maximum deviation of 4.9% and 3.7% for LEE and CCT, respectively. We also conducted a comparison between our model and the previous Kubelka-Munk (KM) theory. It has been revealed that the KM theory may overestimate the phosphor heating due to lacking of the blue light scattering effect.

5.
PLoS One ; 13(6): e0198072, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29944667

RESUMO

Guangdong, Guangxi and Chongqing are emerging sericulture areas in China where the production of mulberry leaves is huge. In order to identity high quality mulberry leaves that are suitable for healthy products to expand planting, 24 samples from three regions (Guangdong, Guangxi, Chongqing) in the south of China were quantified for two alkaloids (1-deoxynojirimycin and fagomine) and five phenols (chlorogenic acid, rutin, isoquercitrin, etc.) using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Additionally, the total phenolic and total flavonoid contents, antioxidant and glycosidase inhibitory activities (hypoglycemic activity) were tested using different assays (DPPH, ABTS, FRAP) to comprehensively evaluate the quality of the mulberry leaves. The contents of DNJ and fagomine ranged from 0.401±0.003 to 5.309±0.036 mg/g and from 0.279±0.031 to 2.300±0.060 mg/g, respectively. The main phenolic constituents were chlorogenic acid, rutin and isoquercitrin, with chlorogenic acid present in the highest concentrations, ranging from 3.104±0.191 to 10.050±0.143 mg/g. The antioxidant activity exhibited a tendency as follows: Guangxi > Guangdong > Chongqing, except for two samples from Chongqing, which showed the highest antioxidant activity. Based on our study, mulberry leaves from Guangdong and Guangxi could be future sources of natural hypoglycemic and antioxidant products.

6.
Adv Mater ; 30(22): e1707237, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29665110

RESUMO

"Fata Morgana" or "Mirage" phenomena have long been captivated as optical illusions, which actually relies on gradient-density air or vapor. Man-made optical illusions have witnessed significant progress by resorting to artificially structured metamaterials. Nevertheless, two long-standing challenges remain formidable: first, exotic parameters (negative or less than unity) become inevitable; second, the signature of original object is altered to that of a virtual counterpart. It is thus not able to address the holy grail of illusion per se, since a single virtual object still exposes the location. In this study, those problems are successfully addressed in a particular setup-illusion thermotics, which identically mimics the exterior thermal behavior of an equivalent reference and splits the interior original heat source into many virtual signatures. A general paradigm to design thermal illusion metadevices is proposed to manipulate thermal conduction, and empower robust simultaneous functions of moving, shaping, rotating, and splitting heat sources of arbitrary cross sections. The temperature profile inside the thermal metadevice can mislead the awareness of the real location, shape, size, and number of the actual heat sources. The present concept may trigger unprecedented development in other physical fields to realize multiple functionalized illusions in optics, electromagnetics, etc.

7.
Nanotechnology ; 28(42): 425204, 2017 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-28752826

RESUMO

Human comfort has become one of the most important criteria in modern lighting architecture. Here, we proposed a tuning strategy to enhance the non-image forming photobiological effect on the human circadian rhythm based on quantum-dots-converted white light-emitting diodes (QDs-WLEDs). We introduced the limiting variability of the circadian action factor (CAF), defined as the ratio of circadian efficiency and luminous efficiency of radiation. The CAF was deeply discussed and was found to be a function of constraining the color rendering index (CRI) and correlated color temperatures. The maximum CAF variability of QDs-WLEDs was found to be dependent on the QDs' peak wavelength and full width at half maximum. With the optimized parameters, the packaging materials were synthesized and WLEDs were packaged. Experimental results show that at CRI > 90, the maximum CAF variability can be tuned by 3.83 times (from 0.251 at 2700 K to 0.961 at 6500 K), which implies that our approach could reduce the number of tunable channels, and could achieve wider CAF variability.

8.
Opt Express ; 24(26): A1560-A1570, 2016 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-28059319

RESUMO

White light-emitting diodes (WLEDs) with quantum dots (QDs) and phosphor have attracted tremendous attentions due to their excellent color rendering ability. In the packaging process, QDs layer and phosphor-silicone layer tend to be separated to reduce the reabsorption losses, and to maintain the stability of QDs surface ligands. This study investigated the packaging sequence between QDs and phosphor on the optical and thermal performances of WLEDs. The output optical power and PL spectra were measured and analyzed, and the temperature fields were simulated and validated experimentally by infrared thermal imager. It was found that when driven by 60 mA, the QDs-on-phosphor type WLEDs achieved luminous efficiency (LE) of 110 lm/W, with color rendering index (CRI) of Ra = 92 and R9 = 80, while the phosphor-on-QDs type WLEDs demonstrated lower LE of 68 lm/W, with Ra = 57 and R9 = 24. Moreover, the QDs-on-phosphor type WLEDs generated less heat than that of another, consequently the highest temperature in the QDs-on-phosphor type was lower than another, and the temperature difference can reach 12.3°C. Therefore, in terms of packaging sequence, the QDs-on-phosphor type is an optimal packaging architecture for higher optical efficiency, better color rendering ability and lower device temperature.

9.
Zhongguo Zhong Yao Za Zhi ; 40(6): 1061-5, 2015 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-26226745

RESUMO

The viability and life span of pollen were evaluated by TTC (2,3,5-triphenyl tetrazlium chloride) and the peroxidase solution, the stigma receptivity were estimated by benzidine-H2O2 method and the fruiting characteristics were investigated. The results showed that (1) Anoectochilus roxburghii and A. formosanus appeared the same up-and-down trend of the pollen viability, increased and then decreased. The storage temperature and storage time had significant impact on the pollen viability. With the extension of storage time, the pollen activity decreased. 4 degrees C refrigerator storage may be extended the pollen vitality. (2) The stigma had receptivity in 1st day and reached the highest level in the 4th day after blooming. A. roxburghii lost receptivity in the 8th day while A. formosanus lost receptivity in the 10th day after blooming. (3) The different pollination had significant impact on seed setting rate. The seed setting rate of artificial cross-pollination was higher than that of the artificial self-pollination. Collecting pollen in the 3rd day and carrying out artificial cross-pollination in the 4th day after blooming can significantly improve seed setting rate. The results provided technical assurance for A. roxburghii and A. formosanus breeding of new varieties and seed breeding.


Assuntos
Flores/fisiologia , Frutas/crescimento & desenvolvimento , Orchidaceae/fisiologia , Pólen/crescimento & desenvolvimento , Sobrevivência Celular , China , Orchidaceae/crescimento & desenvolvimento , Reprodução , Temperatura Ambiente
10.
Appl Opt ; 54(17): 5542-8, 2015 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-26192858

RESUMO

In this study, a brightness-enhancement-film- (BEF) adaptive method is proposed to design freeform lenses for enhancing brightness performance in a direct-lit light-emitting diode (LED) backlight system. A detailed design algorithm is presented based on the analysis of the output optical properties of the BEF. By introducing a constriction factor, we can control the light intensity distribution curve at will to adapt to the characteristics of the BEF and make more light transmit through the BEF. Compared with an LED backlight system without a freeform lens, the BEF-adaptive lens method can improve axial luminance by 20.67% and output efficiency by 6.02%.

11.
Zhongguo Zhong Yao Za Zhi ; 39(13): 2456-9, 2014 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-25276962

RESUMO

Nine morphologic traits, plant height, ground diameter, leaf length, leaf width, leaf area of plant, leaf fresh weight, blades, length/width ratio, plant fresh weight of Anoectochilus roxburghii from 13 different areas were determined for correlation analysis, path analysis and principal components analysis. Different source of morphological trait variation coefficient of A. roxburghii was 2.96% -12.59%, plant fresh weight was significant positively correlated with ground diameter, plant height and leaf number, and positively correlated with leaf fresh weight. Path analysis showed that plant height had the largest positive direct effect on plant fresh weight, the leaf fresh weight and blades number had indirect effects on the plant fresh weight. Through principal component analysis, morphological traits of A. roxburghii can be divided into "Determinants of high-yielding morphology" and "Determinants of leaf production". In the actual process of production and breeding of A. roxburghii, we should pay attention to plant height, leaf fresh weight, blades numbers and other traits.


Assuntos
Orchidaceae/anatomia & histologia , Orchidaceae/crescimento & desenvolvimento , China , Orchidaceae/química , Orchidaceae/classificação , Fenótipo , Folhas de Planta/anatomia & histologia , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento
12.
Zhongguo Zhong Yao Za Zhi ; 39(5): 785-9, 2014 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-25204165

RESUMO

The morphological index of the seedlings including the plants height, the ground diameter, the leaf amounts, the fresh weight of the whole plant and the ratio of height to diameter was measured and the principal components were analyzed so as to determine the grading index, and stepwise cluster analysis was applied for clustering analysis. Pot experiments were used to measure the indicators of plant growth and development, the yield and the quality. The results showed that the height and ground diameter were determined as the quality indicators of the seedlings grading and the standard quality grading of seedlings of Anoectochilus roxburghii was initially set up, different seeding plants influenced the plants growth and the yield. The ground diameter of the class I was larger than that of the class II and III, so as the yield. The seedling grading had no obvious effect on the internal quality of medicinal materials. The results of the study provide the basis for standard cultivation of A. roxburghii.


Assuntos
Orchidaceae/crescimento & desenvolvimento , Plântula/classificação , Medicamentos de Ervas Chinesas/análise , Orchidaceae/química , Orchidaceae/classificação , Controle de Qualidade , Plântula/química , Plântula/crescimento & desenvolvimento
13.
Zhongguo Zhong Yao Za Zhi ; 39(8): 1386-90, 2014 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-25039169

RESUMO

The mycelium growth and sporulation in different temperature, pH value and light conditions were detected by using the crossing and haemocytometer method. The toxicity of five fungicides to Fusarium oxysporum was tested by mycelia growth method, so as to provide the reference for prevention and control against F. oxysporum. The optimum temperature and pH value of F. oxysporum to grow and spore were 28 degrees C and 6-7. Alternating light and darkness promoted growth and sporulation of bacterial colony. As for five fungicides, the EC50 of tebuconazole was 10.02 mg x L(-1), 92.50 times as much as carbendazim. The EC50 of myclobutanil and Fuxing was 91.23, 96.68 mg x L(-1), respectively. Tebuconazole showed the most tremendous inhibitory effect and control efficiency on F. oxysporum.


Assuntos
Fungicidas Industriais/farmacologia , Fusarium/efeitos dos fármacos , Fusarium/crescimento & desenvolvimento , Orchidaceae/microbiologia , Doenças das Plantas/microbiologia , Micélio/efeitos dos fármacos , Micélio/crescimento & desenvolvimento , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/crescimento & desenvolvimento
14.
Zhongguo Zhong Yao Za Zhi ; 39(6): 1075-82, 2014 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-24956854

RESUMO

OBJECTIVE: To study the molecular action mechanism of active constituents desoxyrhaponticin (DES) and human serum albumin (HSA). METHOD: Under the simulated physiological condition, computer analog technology, fluorescent spectrometry and ultraviolet spectrum were combined to study the binding mechanism between drug and protein. RESULT: Molecular modeling was adopted to establish the binding model between DES and HSA, suggesting that the interaction force maintaining drug and protein is mainly the hydrophobic interaction with a hydrogen-bond interaction. The results from spectroscopy indicated that the interaction between DES and HSA is a dynamic binding process with a high intensity. The value of the binding distance (r) between DES and HSA was low, which demonstrate the occurrence of energy transfer. DES made an impact on HSA' structural domain microcell conformation, which resulted in hydrophobic changes in binding areas. According to the fluorescent phase diagram technical analysis, the changes in the DES-HSA reaction conformational pattern showed a "two-state" model. According to the obtained thermodynamic parameters for the DES-HSA interaction, the interactional force between DES and HSA was mainly a hydrophobic interaction. The fluorescence polarization proved that a non-covalent compound was generated during the interaction between DES and HSA. CONCLUSION: The spectrum experiment showed consistent results with the computer analog technology, which could provided certain reference for studies on the interaction between DES and HSA.


Assuntos
Modelos Moleculares , Albumina Sérica/metabolismo , Estilbenos/metabolismo , Humanos , Ligação Proteica , Conformação Proteica , Albumina Sérica/química , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Termodinâmica
15.
Zhongguo Zhong Yao Za Zhi ; 39(1): 44-7, 2014 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-24754166

RESUMO

Compared with living spray method, it focused on the investigation of different inoculation methods, various inoculation concentration and the influence of different seeding age on soft rot-resistance in Jinxianlian. The results showed that (1) Inoculated with dropping connection, the difference of disease index between A. roxburghii and A. formosanus was grate, so that the disease-resistance could be obviously distinguished. (2) When the inoculation concentration was 1.0 x 10(7) cfu x mL(-1), the difference of disease index was relatively obvious and the disease-resistance could be differentiated well. (3) At the moment of 4-month seeding inoculation, a certain difference of the disease index between A. roxburghii and A. formosanus was existed, so, relatively, it could accurately reflect the resistance difference between various species. With the inoculation of dropping connection, A. roxburghii and A. formosanus of 4-month seeding age was put in the bacteria suspension of inoculation concentration of 1.0 x 10(7) cfu x mL(-1). The identification was taken up after 5 days in the incubator under the condition of 14 h daylight and 28 degrees C. The identification result was conformed with that of the living spray method. To investigate the identification method of in vitro evaluation of soft rot-resistance of Jinxianlian so as to provide the foundation for germplasm utilization and excellent cultivars breeding.


Assuntos
Doenças das Plantas/microbiologia
16.
Sci Rep ; 4: 3600, 2014 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-24398592

RESUMO

Transformation thermodynamics, as one of the important branches among the extensions of transformation optics, has attracted plentiful attentions and interests recently. The result of transformation thermodynamics, or called as "thermal cloak", can realize isothermal region and hide objects from heat. In this paper, we presented the concept of "reverse thermal cloak" to correspond to the thermal cloak and made a simple engineering definition to identify them. By full-wave simulations, we verified that the reverse thermal cloak can concentrate heat and realize local heating. The performance of local heating depends on the anisotropic dispersion of the cloaking layer's thermal conductivity. Three-dimensional finite element simulations demonstrated that the reverse thermal cloak can be used to heat up objects. Besides pre-engineered metamaterials, such reverse thermal cloak can even be realized with homogenous materials by alternating spoke-like structure or Hashin coated-sphere structure.

17.
Artigo em Inglês | MEDLINE | ID: mdl-24211810

RESUMO

Rhizoma Atractylodis Macrocephalae (RAM) is a commonly used food and traditional Chinese medicine (TCM), which traditionally strengthens the spleen, benefits vital energy, eliminates dampness, and promotes hidroschesis. Its primary effective constituents are polysaccharides and volatile oil, whose main components are atractylenolide I and III. Fourier transform near-infrared spectroscopy (FT-NIR) is widely used in TCM research. However, determination of atractylenolides in RAM using FT-NIR has not been described. In this study, a new method for the determination of atractylenolides I and III in RAM by NIR was established. The spectral characteristics of atractylenolides I and III were obtained by second derivative multiple scattering correction, and its chart to the original absorbance spectra. Additionally, in combination with the partial least squares (PLS) algorithm, the calibration process was performed for the quantitation of the samples. The root mean square error of cross-validation of the PLS models for atractylenolides I and III was 0.0387 and 0.0358, and the determination coefficient of quantitative models was 96.63 and 96.16, respectively. This study demonstrated that NIR spectroscopy can be used to analyze quickly and efficiently the contents of atractylenolides I and III in RAM.


Assuntos
Antagonistas Colinérgicos/análise , Medicamentos de Ervas Chinesas/química , Lactonas/análise , Sesquiterpenos/análise , Análise dos Mínimos Quadrados , Sensibilidade e Especificidade , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Espectroscopia de Luz Próxima ao Infravermelho/métodos
18.
Opt Express ; 21(21): 25381-8, 2013 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-24150380

RESUMO

Current crowding effects (CCEs) on light extraction efficiency (LEE) of conventional GaN-based light-emitting diodes (LEDs) are analyzed through Monte Carlo ray-tracing simulation. The non-uniform radiative power distribution of the active layer of the Monte Carlo model is obtained based on the current spreading theory and rate equation. The simulation results illustrate that CCE around n-pad (n-CCE) has little effect on LEE, while CCE around p-pad (p-CCE) results in a notable LEE droop due to the significant absorption of photons emitted under p-pad. LEE droop is alleviated by a SiO2 current blocking layer (CBL) and reflective p-pad. Compared to the conventional LEDs without CBL, the simulated LEE of LEDs with CBL at 20 A/cm² and 70 A/cm² is enhanced by 7.7% and 19.0%, respectively. It is further enhanced by 7.6% and 11.4% after employing a reflective p-pad due to decreased absorption. These enhancements are in accordance with the experimental results. Output power of LEDs with CBL is enhanced by 8.7% and 18.2% at 20 A/cm² and 70 A/cm², respectively. And the reflective p-pad results in a further enhancement of 8.9% and 12.7%.

19.
Opt Express ; 21(4): 5071-3, 2013 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-23482040

RESUMO

In a recent paper, Park et al. [Opt. Express 20(9), 10218 (2012)] demonstrated that large micro-size cube phosphors are an outstanding potential candidate for scatter-free phosphors in white phosphor-converted light-emitting diodes (pc-LEDs). They found that large micro-size cube phosphors can lead to higher luminous efficiency (LE), higher packaging efficiency (PE), and reduced influences of ambient temperature and applied current. In this comment, we further discussed the large micro-size phosphors on the angular color uniformity (ACU). It is found that when the phosphor particle size increases from 30 µm to 100 µm, the ACU decreases from 0.91 to 0.86.


Assuntos
Cor , Iluminação/instrumentação , Semicondutores
20.
Opt Express ; 20(13): 13727-37, 2012 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-22714438

RESUMO

A conformal phosphor coating can realize a phosphor layer with uniform thickness, which could enhance the angular color uniformity (ACU) of light-emitting diode (LED) packaging. In this study, a novel freeform lens was designed for simultaneous realization of LED uniform illumination and conformal phosphor coating. The detailed algorithm of the design method, which involves an extended light source and double refractions, was presented. The packaging configuration of the LED modules and the modeling of the light-conversion process were also presented. Monte Carlo ray-tracing simulations were conducted to validate the design method by comparisons with a conventional freeform lens. It is demonstrated that for the LED module with the present freeform lens, the illumination uniformity and ACU was 0.89 and 0.9283, respectively. The present freeform lens can realize equivalent illumination uniformity, but the angular color uniformity can be enhanced by 282.3% when compared with the conventional freeform lens.


Assuntos
Lentes , Iluminação/instrumentação , Semicondutores , Desenho de Equipamento , Análise de Falha de Equipamento
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