scholarly journals Tunable negative group index in metamaterial structures with large form birefringence

2010 ◽  
Vol 18 (2) ◽  
pp. 463 ◽  
Author(s):  
Kirill Sinchuk ◽  
Richard Dudley ◽  
John D. Graham ◽  
Michael Clare ◽  
Mesfin Woldeyohannes ◽  
...  
Keyword(s):  
Group Index ◽  
Negative Group ◽  
Large Form ◽  
Form Birefringence

77‐4: Large Form Birefringence Realized by Dielectric Subwavelength Grating

2019 ◽  
Vol 50 (1) ◽  
pp. 1110-1113
Author(s):  
Dunhang Quan ◽  
Hao Jia ◽  
Weihao Li ◽  
Xing Cheng ◽  
Hoi-Sing Kwok
Keyword(s):  
Subwavelength Grating ◽  
Large Form ◽  
Form Birefringence

Guided Modes of Positive and Negative Group Index in the Honeycomb Photonic Crystal Waveguides

2013 ◽  
Vol 717 ◽  
pp. 153-157
Author(s):  
W. Amorntep ◽  
P. Wanchai
Keyword(s):  
Photonic Crystal ◽  
Optical Communication ◽  
Photon Emission ◽  
Honeycomb Lattice ◽  
Group Index ◽  
Photonic Crystal Waveguide ◽  
Negative Group ◽  
Optical Communication System ◽  
Guided Modes ◽  
Photon Source

A guided mode of positive and negative group index structure is essential to quantum optics for design and development of high efficiency optical devices which are useful to security optical communication system and to diverse applications such as Optical Time-Division-Multiplexing, Optical Switch, Laser, LED, Entangled Photon Source and Single Photon Source. Thus, we proposed to develop an efficient photon emission along line defect of two-dimensional honeycomb photonic crystal waveguide in the silicon slab. The honeycomb lattice of circular air holes on a silicon plate is simulated to obtain two nearest guided modes between positive and negative group index regimes. This significant property shows the potential applied guided modes of photonic crystal waveguide enhancing spontaneous emission for controlling photon emission between two resonance frequencies. Significantly, this work is oriented to produce the novel optical devices for control photon emission in the optical communication system. In addition to the honeycomb lattice, it can easily be made on a Si on insulator (SOI) wafer.

Optical Properties of Organic Complexes of Montmorillonite

Clay Minerals ◽  
1970 ◽  
Vol 8 (4) ◽  
pp. 405-419 ◽  
Author(s):  
R. Greene-Kelly
Keyword(s):  
Optical Properties ◽  
Aromatic Compounds ◽  
Optical Constants ◽  
Large Form ◽  
Form Birefringence ◽  
Orientation Effects ◽  
Suitable Medium ◽  
Organic Complexes ◽  
Optical Examination ◽  
Intrinsic Birefringence

AbstractThe optical properties of oriented montmorillonite aggregates were measured in both non-complexing and complexing media. The changes observed lead to the following conclusions. Preparing oriented aggregates of clays for optical examination requires considerable care to avoid spurious orientation effects. In determining the optical constants of montmorillonite aggregates the medium must wet and enter the aggregate readily and displace the air, particularly from the smaller pores, otherwise large form birefringence effects of uncertain magnitude will occur. A suitable medium is likely to be one that complexes montmorillonite. The complex it forms must have relatively isotropic interlamellar layers and this is more likely with isodimensional molecules. Consideration of complexes with simple compounds suggests that the intrinsic birefringence of aggregates is overestimated by conventional techniques.Forming complexes with aromatic compounds usually results in the birefringence of the aggregate being essentially determined by the orientation and anisotropy of the intercalated molecules.

Energy Velocity in Negative Group Index Structures

2008 ◽  
Author(s):  
Weiguo Yang ◽  
John O. Schenk ◽  
Michael A. Fiddy
Keyword(s):  
Group Index ◽  
Index Structures ◽  
Negative Group

Processing of Social Identity Threats

2013 ◽  
Vol 44 (6) ◽  
pp. 361-372 ◽  
Author(s):  
Natascha de Hoog
Keyword(s):  
Social Identity ◽  
Social Identification ◽  
Negative Group ◽  
Identity Threat ◽  
Neutral Group ◽  
Threat Perceptions ◽  
Social Identity Threat ◽  
Identity Threats ◽  
Group Information ◽  
Source Study

The underlying process of reactions to social identity threat was examined from a defense motivation perspective. Two studies measured respondents’ social identification, after which they read threatening group information. Study 1 compared positive and negative group information, attributed to an ingroup or outgroup source. Study 2 compared negative and neutral group information to general negative information. It was expected that negative group information would induce defense motivation, which reveals itself in biased information processing and in turn affects the evaluation of the information. High identifiers should pay more attention to, have higher threat perceptions of, more defensive thoughts of, and more negative evaluations of negative group information than positive or neutral group information. Findings generally supported these predictions.

Linkage between H. pylori Infection and TNF-α polymorphism in The Pregnant Women

2018 ◽  
Vol 9 (SPL1) ◽  
Author(s):  
Ghaidaa Raheem Lateef ◽  
Azhar Omaran Al-Thahab
Keyword(s):  
Pregnant Women ◽  
Serum Antibody ◽  
Rapid Test ◽  
Negative Group ◽  
Positive Group ◽  
Gynecology And Obstetrics ◽  
Tnf Α ◽  
Significant Difference ◽  
Pcr Products ◽  
H Pylori

A study was performed on 100 pregnant women in the outpatient department of gynecology and obstetrics of Maternity and Children Hospital in Al-Diwaniya City during the period between (March to September 2016). One hundred blood samples (50 for patients and 50 for control) were collected under the supervision of the treating gynecologist. The detection of Helicobacter. pylori was done by the use of the serum antibody Rapid test. The results showed that 50 (100%) were positive and 50 (100%) were negative for H. pylori in above method.All blood of patients and control samples were used for the extraction of genomic DNA,where the 107 bp PCR product size. Genotyping of the TNF-α-308 SNP (G/A)was performed by restriction fragment length polymorphism PCR (RFLP-PCR). PCR products were digested with restr NcoI iction enzyme. Individuals with the TNF-α-308(GG) homozygote produced digested DNA bands at 80,and 20 bp bp. A heterozygous genotype ofTNF-α-308 (GA)produced 107 bp,80 bp,and 20 bp bands. Individuals with the TNF-α-308 (AA) homozygote genotype had no amplicon digested and generated only one band of 107 bp. There was a significant difference in the frequency of the TNF-α-308(GG)genotype between H. pylori positive group and H. pylori negative group(72%,78% respectively). Also for GA genotype,there was a significant difference between H. pylori positive group and H. pylori negative group(24%,18% respectively). Concerning the frequency of the TNF-α-308 (AA)genotype between H. pylori positive group and H. pylori negative group,there was no significant difference between the two groups.

UJI AKTIVITAS HEPATOPROTEKTOR KOMBINASI EKSTRAK ETANOL DAUN PANDAN WANGI (Pandanus amaryllifolius roxb) DAN KAYU MANIS (Cinnamomum burmanii) TERHADAP KADAR MDA YANG DIINDUKSI PARASETAMOL

2020 ◽  
pp. 68-73
Author(s):  
Yuni Asri Mulatsih Agami ◽  
Eka Wisnu Kusuma
Keyword(s):  
Oxidative Stress ◽  
Ethanol Extract ◽  
Optimal Dose ◽  
Experimental Methods ◽  
Positive Control ◽  
Negative Control ◽  
Male Rats ◽  
Negative Group ◽  
Ic50 Value ◽  
Dose Combination

Kasus penyakit hati semakin meningkat seiring penggunaan senyawa hepatotoksin salah satunya karena penggunaan parasetamol dengan dosis berlebih. Hal tersebut dapat meningkatkan produksi radikal bebas sehingga memicu terjadinya stress oksidatif yang dapat menimbulkan kerusakan jaringan yang ditandai dengan peningkatan kadar Malondialdehyde (MDA). Stress oksidatif dapat diatasi dengan antioksidan dari berbagai tanaman. Kulit kayu manis memiliki aktivitas antioksidan dengan nilai IC50 53ppm dan daun pandan wangi 39,7%  Penelitian ini bertujuan untuk mengetahui aktivitas kombinasi ekstrak etanol daun pandan wangi dan kayu manis dalam menurunkan kadar MDA. tikus yang diinduksi parasetamol. Penelitian menggunakan metode eksperimental, dilakukan selama 9 hari dengan 30 ekor tikus jantan dibagi menjadi 6 Kelompok, yaitu: Normal diberi aquadest, Kontrol Positif diberi silimarin 100 mg/kgBB, Kontrol Negatif diberi CMC-Na 0,05%, serta 3 kelompok lainnya diberi kombinasi ekstrak daun pandan wangi:kayu manis berturut-turut dosis I (25:75), dosis II (50:50), dosis III (75:25). Semua kelompok diinduksi parasetamol 2,5 g/kgBB pada hari ke-7  setelah 30 menit perlakuan, kecuali kelompok normal. Pada hari ke 9 dilakukan pengukuran kadar MDA dengan metode TBARs menggunakan spektrofotometri. Pemberian kombinasi ekstrak etanol daun pandan wangi dan kayu manis dapat menurunkan kadar MDA dengan kombinasi dosis yang paling optimal adalah 75:25 berdasarkan statistik dengan nilai signifikan 0,000<0,05 dibandingkan dengan kelompok negatif.    Cases of liver disease have increased with the use of hepatotoxin compounds, one of which is due to the use of paracetamol with excessive doses. This can increase the production of free radicals so that it triggers oxidative stress which can cause tissue damage which is characterized by increased levels of Malondialdehyde (MDA). Oxidative stress can be overcome with antioxidants from various plants. Cinnamomum burmanii has antioxidant activity with IC50 value of 53ppm and Pandanus amarrylifolius 39.7%. This study aims to determine the combined activity of ethanol extract of Pandanus amarrylifolius and Cinnamomum burmanii  in reducing MDA levels. Paracetamol-induced rats. Research using experimental methods, conducted for 9 days with 30 male rats divided into 6 groups, namely: Normal given aquadest, Positive Control were given silimarin 100 mg / kgBB, Negative Control was given CMC-Na 0.05%, and 3 other groups were given a combination of Pandanus amarrylifolius extract: Cinnamomum burmanii dose I (25:75), dose II (50:50), dose III (75:25). All groups induced paracetamol 2.5 g / kgBB on the 7th day after 30 minutes of treatment, except the normal group. On the 9th day MDA levels were measured using the TBARs method using spectrophotometry. Giving a combination of Pandanus amarrylifolius and Cinnamomum burmanii ethanol extract can reduce MDA levels with the most optimal dose combination is 75:25 based on statistics with a significant value of 0,000<0.05 compared with the negative group.

Negative Group Velocity of Surface Polaritons in Metal Foil Nanostructure

2017 ◽  
Vol 9 (3) ◽  
pp. 03039-1-03039-4 ◽  
Author(s):  
Y. M. Aleksandrov ◽  
◽  
V. V. Yatsishen ◽  
Keyword(s):  
Group Velocity ◽  
Metal Foil ◽  
Negative Group ◽  
Surface Polaritons ◽  
Negative Group Velocity
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