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1.
Zhonghua Er Ke Za Zhi ; 60(5): 442-446, 2022 May 02.
Artigo em Chinês | MEDLINE | ID: mdl-35488638

RESUMO

Objective: To explore the risk factors for syncope in children with severe idiopathic pulmonary arterial hypertension (IPAH). Methods: Forty-four patients (age<18 years) with IPAH admitted to the Department of Pediatric Cardiology, Beijing Anzhen Hospital between May 2011 and October 2021 were retrospectively included. Patients were devided into syncope group and non-syncope group. Clinical manifestation and hemodynamic parameters including echocardiography, blood tests, right heart catheterization and acute pulmonary vascular expansion test were compared between two groups. Comparisons between groups were performed with unpaired Student t test, or Mann-Whitney U test or chi-square test. Logistic regression was used to calculate the odds ratio (OR) for parameters with statistically significant differences between groups and analyze the statistical correlation. Results: Among the 44 patients, 16 were males, the onset age was (7.2±3.9) years. Twenty-four (55%) children presented with 1 to 11 times of episodes of syncope, and 18 cases of whom induced by physical activity. Syncope group had a larger proportion of New York Heart Association (NYHA) heart function class Ⅲ-Ⅳ (67% (16/24) vs. 25% (5/20), χ2=7.59, P=0.006), higher brain natriuretic peptide (BNP) value ((251±39) vs. (61±40) pg/L, t=-2.18, P=0.035), higher pulmonary-to-aorta diameter ratio (1.6±0.4 vs. 1.4±0.2, t=-2.25, P=0.030) and larger pulmonary vascular resistance index ((22±11) vs. (16±7) WU/m2, t=-2.13, P=0.039) compared with non-syncope group. The proportion of patent foramen ovale (4% (1/24) vs. 45% (9/20), χ2=10.36, P=0.001), left ventricular ejection fraction (LVEF) ((68±5)% vs. (72±8)%, t=2.23, P=0.031) and the positive rate of acute pulmonary vascular expansion test (8% (2/24) vs. 35% (7/20), χ2=4.77, P=0.029) of syncope group were significantly lower than those of non-syncope group. Multiple Logistic regression analysis showed that NYHA heart function Ⅲ-Ⅳ (OR=6.787, 95%CI 1.445-31.880), pulmonary vascular resistance index (OR=1.247, 95%CI 1.020-1.525) and BNP (OR=1.036, 95%CI 1.007-1.066) were independent risk factors for syncope. The patent foramen ovale (OR=0.010, 95%CI 0.000-0.586) was a protective factor for syncope. Conclusions: NYHA cardiac function grade, pulmonary vascular resistance index and BNP are independent risk factors for syncope. Patent foramen ovale is a protective factor for syncope. Exercise is the main inducement of syncope in children with IPAH.


Assuntos
Forame Oval Patente , Adolescente , Criança , Pré-Escolar , Hipertensão Pulmonar Primária Familiar , Feminino , Humanos , Masculino , Estudos Retrospectivos , Fatores de Risco , Volume Sistólico , Síncope/etiologia , Função Ventricular Esquerda
2.
Case Rep Dent ; 2021: 7819818, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34707911

RESUMO

An 80-year-old man sought treatment at our hospital. He was dissatisfied with his old complete denture due to its poor stability and retention. The old complete denture had been used for about 20 years. The prolonged use of an unsuitable complete denture led the patient to be accustomed to unilateral mastication (UM). Due to the patient long-term habitual mandibular deviation, using the physiological technique to get the centric relation (CR) achieved an incorrect horizontal maxillomandibular record. This clinical report presents a technique using the existing complete denture mounted with a Gothic arch tracer to determine the CR. This technique is an inexpensive, simple, and reliable method that allows fabricating the final impression and obtaining the maxillomandibular relationship record (MMRR) in one step.

3.
Zhonghua Yu Fang Yi Xue Za Zhi ; 55(8): 978-982, 2021 Aug 06.
Artigo em Chinês | MEDLINE | ID: mdl-34445836

RESUMO

Objective: This study retrospectively analyzed an outbreak of dengue fever in Puyang of Henan province in 2019, in order to find the sources of infection. Methods: Dengue virus IgM/IgG and NS1 antigen were tested by colloidal gold method. E gene was amplified by PCR. MegaX was used for sequences alignment to construct evolutionary distance trees. Results: After clinical and laboratory confirmation, there were 81 cases of dengue fever, 17 of which were imported case who were local farmers and worked in Combadia and Thailand, and 64 of which were indigenous cases. The E gene alignment results showed that the pathogen of this epidemic was Vietnamese 1 and highly homologous with the Vietnamese strain. After the local outbreak, dengue virus E gene developed a nucleotide site mutation which can be steadily transmission. Conclusion: The dengue fever outbreak in Puyang was a local outbreak caused by dengue virus type 1, which was associated with imported cases. Gene sequencing showed that the imported pathogen had a relatively stable and transmissible nucleotide mutation after the local epidemic.


Assuntos
Vírus da Dengue , Dengue , Dengue/epidemiologia , Vírus da Dengue/genética , Surtos de Doenças , Humanos , Filogenia , Estudos Retrospectivos
4.
Lett Appl Microbiol ; 72(5): 570-577, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33474743

RESUMO

Effect of rhizobial inoculation and nitrate application on the content of bioactive compounds in legume plants is an interesting aspect for interactions among microbes, plants and chemical fertilizers, as well as for cultivated practice of legumes. In this study, nitrate (0, 5 and 20 mmol l-1 ) and Bradyrhizobium arachidis strain CCBAU 051107T were applied, individually or in combination, to the root rhizosphere of the medicinal legume Sophora flavescens Aiton (SFA). Then the plant growth, nodulation and active ingredients including (oxy)matrine of SFA were determined and compared. Rhizobial inoculation alone significantly increased the numbers and fresh weight of root nodules. Nodulation was significantly inhibited due to nitrate (5 and 20 mmol l-1 ). Only oxymatrine was detected in the control plants without rhizobial inoculation and nitrate supplement, while both oxymatrine and matrine were synthesized in plants treated with inoculation of B. arachidis or supplied with nitrate. The content of oxymatrine was the highest in plants inoculated solely with rhizobia and was not significantly altered by additional application of nitrate. Combinations of B. arachidis inoculation and different concentrations of nitrate did not significantly change the concentrations of (oxy)matrine in the plant. In conclusion, sole rhizobial inoculation was the best approach to increase the contents of key active ingredients oxymatrine and matrine in the medicinal legume SFA.


Assuntos
Alcaloides/análise , Bradyrhizobium/metabolismo , Nodulação/fisiologia , Raízes de Plantas/microbiologia , Quinolizinas/análise , Fertilizantes/análise , Nitratos/farmacologia , Rizosfera , Sophora/química , Sophora/microbiologia , Simbiose/fisiologia , Verduras , Matrinas
5.
Zhonghua Liu Xing Bing Xue Za Zhi ; 41(10): 1703-1709, 2020 Oct 10.
Artigo em Chinês | MEDLINE | ID: mdl-33297630

RESUMO

Objective: To examine the trend of burden on ischemic heart disease (IHD) and epidemiological transition on related risk factors among the Chinese population from 1990 to 2017. Methods: Based on open access data from the Global Burden of Disease (GBD) 2017 Study, we used years of life lost (YLD), years lived with disability (YLL), and disability-adjusted of life years (DALY) to describe the changes of IHD burden stratified by different sex and age groups from 1990 to 2017. We applied population-attributable faction (PAF) to analyze the burden attributable to risk factors and epidemiological transition. Results: In 2017, rates on YLD, YLL, and DALY for IHD were 74.2/100 000, 2 459.6/100 000, and 2 523.1/100 000, respectively. DALY rate and YLL rate for IHD in males were invariably higher than those in females except for YLD rate in females. 24 modifiable risk factors were causally associated with IHD. The top five risk factors that influencing DALYs, PAF, and DALY rate in 2017 appeared as: high blood pressure (16.429 million person years, 54.6%, 1 163.1/100 000), high LDL cholesterol (13 941 million person years, 46.3%, 987.0/100 000), diet high in sodium (10.900 million person years, 36.2%, 771.1/100 000), smoking (8.647 million person years, 28.7%, 612.2/100 000), and low-nut diet (7.452 million person years, 24.8%, 527.6/100 000). DALY rate for IHD showed an increase of 90.9%, from 1 116.4/100 000 in 1990 to 2 131.0/100 000 in 2017. Compared with 1990, the YLD rate experienced an evident increase in those aged 15-49 and over 70, in 2017. Annual average growth rate of YLD rate was higher in the ≥70 age group, between 2007 and 2017 (0.4%) than that between 1990 and 2007 (0.2%). The annual average increasing rates of both YLL and DALY were much lower from 2007 to 2017 (0.6%, 0.6%) than those from 1990 to 2007 (1.3%, 1.2%). From 1990 to 2017, DALYs attributed to meaty food (929.7%), beverages with high sugar content (822.7%), and high body-mass index (327.3%) experienced the highest increase. The largest increase in PAF occurred for beverages with high sugar content (400.0%). DALY rates increased for the 8 risk factors whereas decreased on the 7 risk factors, in consecutive rankings between 2007 and 2017. Conclusions: Despite the fact that burden on IHD-caused premature death had been reducing, related disabilities remain challenging with IHD the leading cause of burden, particularly in the ≥70 year-olds. Higher IHD burden from premature death was seen in males but disability appeared higher in females. It is significantly important to strengthen programs on prevention and control for hypertension including reducing modifiable risk factors such as smoking, unreasonable diet habits.


Assuntos
Efeitos Psicossociais da Doença , Isquemia Miocárdica , Adolescente , Adulto , Idoso , China/epidemiologia , Pessoas com Deficiência/estatística & dados numéricos , Feminino , Humanos , Expectativa de Vida/tendências , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/epidemiologia , Anos de Vida Ajustados por Qualidade de Vida , Fatores de Risco , Adulto Jovem
6.
Eur Rev Med Pharmacol Sci ; 24(19): 9880-9888, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-33090391

RESUMO

OBJECTIVE: To explore the correlation of SNHG1 with miR-195-5p, and the mechanism of SNHG1 in prostate cancer (PC). PATIENTS AND METHODS: The prostate cancer patients admitted to our hospital were selected, and the cancer tissues (n=142) and adjacent tissues (n=142) of the patients were collected during the operation. The content of SNHG1 and miR-195-5p in PC was observed, and the PC cell lines were transfected to detect the proliferation, invasion, apoptosis and Epithelial-Mesenchymal Transitions (EMT) capability. RESULTS: SNHG1 was enhanced in PC, while miR-195-5p was decreased (p<0.05). After transfection of DU-145 and PC-3, it was found that silence of SNHG1 or overexpression of miR-195-5p could evidently inhibit the proliferation and invasion, increase the apoptosis (p<0.05). After detecting the EMT markers, it was found that after silencing SNHG1 or over-expressing miR-195-5p, E-cadherin enhanced while N-cadherin and Vimentin reduced (p<0.05). Double Luciferase reports confirmed that SNHG1 could act as a sponge to regulate miR-195-5p, and correlation analysis showed that SNHG1 had a negative correlation with miR-195-5p. Rescue experiments found that si-SNHG1 co-transfected with miR-195-5p-inhibitor could reverse the inhibitory role of si-SNHG1 on prostate cancer cells. CONCLUSIONS: SNHG1 can mediate the proliferation, invasion and EMT of PC by regulating miR-195-5p expression.


Assuntos
MicroRNAs/metabolismo , Neoplasias da Próstata/metabolismo , RNA Longo não Codificante/metabolismo , Apoptose , Proliferação de Células , Células Cultivadas , Transição Epitelial-Mesenquimal/genética , Humanos , Masculino , MicroRNAs/genética , Neoplasias da Próstata/patologia , RNA Longo não Codificante/genética
7.
Eur Rev Med Pharmacol Sci ; 23(5): 2075-2083, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30915752

RESUMO

OBJECTIVE: This study aims to elucidate the regulatory role of long noncoding RNA (lncRNA) LINC00673 in proliferative, invasive and metastatic capacities of papillary thyroid carcinoma (PTC), and to investigate the possible underlying mechanism. PATIENTS AND METHODS: LINC00673 expression in PTC tissues and cell lines was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The correlation between LINC00673 expression and PTC prognosis was analyzed. By plasmid transfection, we constructed PTC cell lines with stable knockdown of LINC00673. The regulatory effect of LINC00673 on the proliferation of K1 and TPC-1 cells were determined by Cell Counting Kit-8 (CCK-8) assay and colony formation assay. The transwell assay was conducted to evaluate the effect of LINC00673 on the metastatic ability of PTC cells. The binding condition between LINC00673 with enhancer of zeste homolog 2 (EZH2) and DNA Methyltransferase 1 (DNMT1) was verified by RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP) and Western blot. The cellular mechanism of p53 in regulating biological behaviors of PTC cells was explored by Western blot. Finally, the gain-of-function experiment was performed to elucidate whether LINC00673 could regulate PTC development by inhibiting p53 expression. RESULTS: LINC00673 expression in PTC tissues was significantly higher than that of the adjacent normal tissues. Besides, higher expression of LINC00673 indicated worse prognosis of PTC. The knockdown of LINC00673 in K1 and TPC-1 cells markedly reduced the proliferative rate. Meanwhile, LINC00673 down-regulation remarkably inhibited the migratory and invasive capacities of K1 and TPC-1 cells. RIP and ChIP assay demonstrated that LINC00673 could bind to EZH2 and DNMT1. Besides, Western blot analysis showed that LINC00673 negatively regulated p53 expression. In addition, the knockdown of p53 in K1 and TPC-1 cells partially reversed the inhibitory effect of LINC00673 deficiency on the proliferation and metastasis of PTC cells. CONCLUSIONS: High expression of LINC00673 in PTC predicts a poor prognosis. LINC00673 remarkably promotes the proliferation and invasion of PTC cells by inhibiting p53 expression by binding to EZH2 and DNMT1.


Assuntos
DNA (Citosina-5-)-Metiltransferase 1/genética , Proteína Potenciadora do Homólogo 2 de Zeste/genética , RNA Longo não Codificante/genética , Câncer Papilífero da Tireoide/mortalidade , Neoplasias da Glândula Tireoide/mortalidade , Proteína Supressora de Tumor p53/metabolismo , Ciclo Celular , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , DNA (Citosina-5-)-Metiltransferase 1/metabolismo , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Prognóstico , Análise de Sobrevida , Câncer Papilífero da Tireoide/genética , Câncer Papilífero da Tireoide/metabolismo , Neoplasias da Glândula Tireoide/genética , Neoplasias da Glândula Tireoide/metabolismo , Regulação para Cima
8.
Zhonghua Yi Xue Za Zhi ; 97(33): 2620-2624, 2017 Sep 05.
Artigo em Chinês | MEDLINE | ID: mdl-28881539

RESUMO

Objective: To explore the incidence of carotid atherosclerosis in staffs of Tsinghua university according to the different age groups, the possible risk factors and conduct a follow-up survey. Methods: Detailed information about physical examination and carotid ultrasound from 832 staffs of Tsinghua University between 2014 to 2016 were reviewed to observe the occurrence and development of atherosclerosis according to different age groups; the correlation between conventional risk factors and carotid arteriosclerosis was studied by multivariate Logistic regression analysis.The process of different degrees of arteriosclerosis in the population was observed one year later. Results: In the past three years, there were 2 024 cases of carotid examination. Among them, there were 832 staffs who had been followed up for more than 6 months. There were 517 cases of carotid atherosclerosis, with 289 males (55.9%) and 228 females (44.1%), and the incidence of atherosclerosis in male was higher than that in female (P<0.05). The 50 to 59 years old, 60 to 69 years old, 70 to79 years old were the age group with high incidence of pure carotid intima-media thickening, atherosclerosis plaque formation and stenosis or occlusion, respectively. After multivariate Logistic regression analysis, hypertension, diabetes and hyperlipidemia were found the independent risk factors for carotid intimal thickening. The follow-up of 832 staffs with ultrasound showed that there was no significant difference in intima-media thickening, plaque formation, stenosis or occlusion after one year (P>0.05). Conclusions: This research suggests that the incidence of atherosclerosis in male is higher than that in female, and hypertension, diabetes and hyperlipidemia are important influencing factors of arteriosclerosis for staffs of Tsinghua University. Early screening, identification of high-risk patients and comprehensive treatment should be done to delay the process of atherosclerosis.In addition, long-term follow-up is necessary in the context of no significant changes within the short-term.


Assuntos
Aterosclerose , Doenças das Artérias Carótidas , Idoso , Artérias Carótidas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Exame Físico , Fatores de Risco , Ultrassonografia
9.
Rev Sci Instrum ; 85(12): 125003, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25554319

RESUMO

Rectification error is a critical characteristic of inertial accelerometers. Accelerometers working in operational situations are stimulated by composite inputs, including constant acceleration and vibration, from multiple directions. However, traditional methods for evaluating rectification error only use one-dimensional vibration. In this paper, a double turntable centrifuge (DTC) was utilized to produce the constant acceleration and vibration simultaneously and we tested the rectification error due to the composite accelerations. At first, we deduced the expression of the rectification error with the output of the DTC and a static model of the single-axis pendulous accelerometer under test. Theoretical investigation and analysis were carried out in accordance with the rectification error model. Then a detailed experimental procedure and testing results were described. We measured the rectification error with various constant accelerations at different frequencies and amplitudes of the vibration. The experimental results showed the distinguished characteristics of the rectification error caused by the composite accelerations. The linear relation between the constant acceleration and the rectification error was proved. The experimental procedure and results presented in this context can be referenced for the investigation of the characteristics of accelerometer with multiple inputs.

10.
Biomed Mater ; 6(6): 065004, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22002676

RESUMO

The purpose of this study was to evaluate the effect of the surface element composition and roughness of dyed or non-dyed zirconia ceramic by air abrasion on the bond durability to resin luting cement. The sintered zirconia ceramic specimens were divided into four groups as follows: polished, dyed/polished, abraded, dyed/abraded. The surface roughness of each group was measured by a 3D laser scanning microscope. Energy-dispersive spectroscopy was applied for identifying and quantifying the elemental composition of the zirconia ceramic surfaces Each group had 20 shear test specimens of zirconia to Panavia F and was divided into two subgroups (n = 10) after 0 or 10 000 thermal cycles to receive the shear test. Compared with polishing, air abrasion significantly reduced the oxygen atom and weight ratio, increased the zirconium atom and weight ratio, increased R(a) and R(y) of zirconia ceramic surface, and also increased the bond strength of dyed and non-dyed zirconia ceramic to Panavia F after 0 and 10 000 thermal cycles. The dying procedure could affect the abraded and non-abraded zirconia ceramic surface oxygen and zirconia element ratios and surface characteristics. However, the dying procedure does not affect the resin bond strength and durability of zirconia ceramic.Corrections were made to this article on 3 November 2011. The footnote for the corresponding authors was incorrectly labelled.


Assuntos
Abrasão Dental por Ar/métodos , Materiais Biocompatíveis/química , Cerâmica/química , Corantes/química , Teste de Materiais , Cimentos de Resina/química , Zircônio/química , Adesividade , Adsorção , Propriedades de Superfície
11.
Biomed Mater ; 5(4): 044101, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20683131

RESUMO

This study aims to evaluate the effect of chemical adhesion by a silane coupler and mechanical retention by hydrofluoric acid (HFA) etching on the bond durability of resin to a dental glass ceramic with leucite crystallites. Half of the ceramic plates were etched with 4.8% HFA (HFA group) for 60 s, and the other half were not treated (NoHFA group). The scale of their surface roughness and rough area was measured by a 3D laser scanning microscope. These plates then received one of the following two bond procedures to form four bond test groups: HFA/cement, NoHFA/cement, HFA/silane/cement and NoHFA/silane/cement. The associated micro-shear bond strength and bond failure modes were tested after 0 and 30 000 thermal water bath cycles. Four different silane/cement systems (Monobond S/Variolink II, GC Ceramic Primer/Linkmax HV, Clearfil Ceramic Primer/Clearfil Esthetic Cement and Porcelain Liner M/SuperBond C&B) were used. The data for each silane/cement system were analyzed by three-way ANOVA. HFA treatment significantly increased the surface R(a) and R(y) values and the rough area of the ceramic plates compared with NoHFA treatment. After 30 000 thermal water bath cycles, the bond strength of all the test groups except the HFA/Linkmax HV group was significantly reduced, while the HFA/Linkmax HV group showed only adhesive interface failure. The other HFA/cement groups and all NoHFA/cement groups lost bond strength completely, and all NoHFA/silane/cement groups with chemical adhesion had significantly higher bond strength and more ceramic cohesive failures than the respective HFA/cement groups with mechanical retention. The result of the HFA/silane/cement groups with both chemical adhesion and mechanical retention revealed that HFA treatment could enhance the bond durability of resin/silanized glass ceramics, which might result from the increase of the chemical adhesion area on the ceramic rough surface and subsequently reduced degradation speed of the silane coupler, rather than the mechanical retention of the ceramic rough surface.


Assuntos
Silicatos de Alumínio/química , Cerâmica/química , Cristalização/métodos , Resinas Sintéticas/química , Adesividade , Simulação por Computador , Ácido Fluorídrico/química , Teste de Materiais , Modelos Químicos , Propriedades de Superfície , Resistência à Tração
12.
Opt Lett ; 34(8): 1210-2, 2009 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-19370120

RESUMO

A wavefront reconstruction and three-dimensional (3-D) shape measurement method by a two-step phase-shifting algorithm with arbitrary phase shift in (0,pi) is proposed. In this method, only two phase-shifted intensities, with the removal of the dc term by an averaging technique in spatial domain or low-pass filter operation in the frequency domain, are needed, and the other additional measurements are no longer required. The simulation for an irregular wavefront has shown the feasibility, and the optical experiment for a 3-D face mask in the case of a sinusoidal fringe projection system has illustrated the validity of the proposed method.

13.
Opt Lett ; 33(14): 1575-7, 2008 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-18628802

RESUMO

Conventional double-random phase encoding is vulnerable to a chosen or known plaintext attack owing to the linearity of the system. We introduce a technique to break down this linearity with an undercover amplitude modulation in the encryption scheme. As an additional key, this operation can significantly enhance the security of the system. A series of computer simulations have shown the effectiveness of this method and its resistance against the known plaintext attack. The design and parameter choice of the amplitude modulator is also discussed.

14.
Opt Lett ; 33(8): 776-8, 2008 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-18414529

RESUMO

An algorithm to extract the arbitrary unknown phase shift and then reconstruct the complex object wave in generalized phase-shifting interferometry (GPSI) without the iteration process and measurement of object wave intensity is proposed. This method can be used for GPSI of any frame number >or=2. Both computer simulations with smooth and diffusing object surfaces and optical experiments have verified the effectiveness of this method over a wide range of phase shifts with very satisfactory results.

15.
Nanotechnology ; 19(2): 025201, 2008 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-21817535

RESUMO

It is well known that the square lattice of isolated single-atom dielectric rods in air does not give rise to complete bandgaps even when asymmetry is introduced to lift some degeneracy. However, in this paper, a new kind of two-dimensional square photonic crystal with isolated single-atom dielectric rods in air formed by holographic lithography is proposed, and the relation between their photonic bandgap properties and their specific holographic design are systematically analyzed. In addition to the large complete relative bandgap, namely 9.68% gap/midgap ratio for the dielectric constant contrast of 13.6:1, this structure has very large tolerance on the system parameters and fabrication conditions. This fact can greatly relax the experimental requirements. This work may demonstrate the unique feature and advantages of photonic crystals made by the holographic method and provide a guideline for their design and fabrication.

16.
Opt Express ; 15(13): 8003-9, 2007 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-19547128

RESUMO

We present a study on negative refractions in the four lowest bands of two-dimensional (2D) square lattices formed by holographic lithography (HL) and compare these features with those of a lattice of the same kind but with regular dielectric columns. The plane wave calculations and FDTD simulations have shown that in some bands or for some interfaces the negative refraction can only happen in holographic structures, and generally the rightness of holographic structures and regular structures of the same kind may be different.

17.
Opt Lett ; 31(13): 1966-8, 2006 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-16770400

RESUMO

A novel fast convergent algorithm to extract arbitrary unknown phase shifts in generalized phase-shifting interferometry (PSI) is proposed and verified by a series of computer simulations. In this algorithm an error function is introduced and then the unknown phase shifts are found by an iterative tangent approach. In combination with the statistical method, this algorithm can give the most exact results in the fewest iteration steps. It can be used for generalized PSI of arbitrary frames for both smooth and diffusing objects and can usually reach the exact phase shifts with only four or five iterations for three- or four-frame PSI.

18.
Opt Lett ; 31(10): 1414-6, 2006 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-16642123

RESUMO

Conventional phase-shifting interferometry (PSI) needs at least three interferograms. A novel algorithm of two-step PSI, with an arbitrary known phase step, by which a complex object field can be reconstructed with only two interferograms is proposed. This algorithm is then applied to an information security system based on double random-phase encoding in the Fresnel domain. The feasibility of this method and its robustness against occlusion and additional noise attacks are verified by computer simulations. This approach can considerably improve the efficiency of data transmission and is very suitable for Internet use.

19.
Opt Express ; 14(18): 8096-102, 2006 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-19529181

RESUMO

We propose a holographic design of five-beam symmetric umbrella configuration, where there are a central beam and four ambient beams symmetrically scattered around the central one with the same apex angle, for fabrication of three-dimensional photonic crystals with tetragonal or cubic symmetries, and systematically analyzed the band gap properties of resultant photonic crystals when the apex angle is continuously increased. Our calculations reveal that large complete photonic band gaps exist in a wide range of apex angle for a relatively low refractive index contrast. Specifically, the face-centered cubic structure with a relative band gap of 25.1% for epsilon = 11.9 can be obtained with this recording geometry conveniently where all the beams are incident from the same half-space. These results will provide us with more understanding of this important recording geometry and give guidelines to its use in experiments.

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