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1.
Sovrem Tekhnologii Med ; 15(2): 48-58, 2023.
Article in English | MEDLINE | ID: mdl-37389017

ABSTRACT

The aim of the study is to find new predictors of postablation atrial fibrillation (AF) recurrence in patients with lone AF using a texture analysis of the periatrial adipose tissue (PAAT) of the left atrium. Materials and Methods: Forty-three patients admitted for lone AF catheter ablation, who had undergone multispiral coronary angiography, were enrolled in the study. PAAT segmentation was performed using 3D Slicer application followed by extraction of 93 radiomic features. At the end of the follow-up period, patients were divided into 2 groups depending on the presence or absence of AF recurrence. Results: 12 months of follow-up after catheter ablation, postablation AF recurrence was reported in 19 out of 43 patients. Of 93 extracted radiomic features of PAAT, statistically significant differences were observed for 3 features of the Gray Level Size Zone matrix. At the same time, only one radiomic feature of PAAT, Size Zone Non Uniformity Normalized, was an independent predictor of postablative recurrence of AF after catheter ablation and 12 months of follow-up (McFadden's R2=0.451, OR - 0.506, 95% CI: 0.331‒0.776, p<0.001). Conclusion: The radiomic analysis of periatrial adipose tissue may be considered as a promising non-invasive method for predicting adverse outcomes of the catheter treatment, which opens the possibilities for planning and correction of patient management tactics after intervention.


Subject(s)
Atrial Fibrillation , Humans , Atrial Fibrillation/diagnostic imaging , Atrial Fibrillation/surgery , Prognosis , Heart Atria/diagnostic imaging , Heart Atria/surgery , Adipose Tissue/diagnostic imaging , Phenotype
2.
Bull Exp Biol Med ; 176(2): 126-132, 2023 Dec.
Article in English | MEDLINE | ID: mdl-38180702

ABSTRACT

The study examined the modes of pulsations of the femoral and carotid arteries of rats in situ (n=14) during acute blood loss, which sequentially caused a deep BP drop, cardiac and respiration arrest, and termination of ECG signals. When BP dropped to 19 (13; 26) mm Hg, the mechanosensitivity of passively pulsing arteries determined by the ratio of the swing range of electroimpedance oscillations of arterial segment to pulse pressure increased by 3.2 (2 ; 4) times (p<0.05). During the decrease of BP to the threshold value of 13 (8; 15) mm Hg, the arterial pulsing mode changed from passive to intermediate and then to the active one characterized by constriction of arterial segment in response to systolic elevation of BP. After cardiac arrest and BP drop almost to zero, the arterial pulsing switched to autonomic rhythmical vasomotions with the rate, which was greater than the frequency of still sustained QRS pulses of ECG. The observed phenomena are explained by transarterial hypotensive transition hypothesis, which argues that peculiarities of pulsations and vasomotions of major arteries during deep BP drop are typical of arterioles under normal or diminished BP. The study refined the hypothesis of "peripheral heart" and its role in hypo- and hypertension.


Subject(s)
Hypertension , Hypotension , Rats , Animals , Blood Pressure/physiology , Carotid Arteries/physiology , Heart Rate/physiology
3.
J Nucl Cardiol ; 29(6): 3586-3589, 2022 12.
Article in English | MEDLINE | ID: mdl-33939163

ABSTRACT

Recently, the applicability of somatostatin receptor-targeted (SSTR-t) radiotracers for post-ischemic myocardial inflammation imaging has been shown using PET. Currently, there are no studies which demonstrate ability of SPECT and technetium-99m SSTR-t radiotracers to detect inflammation, which appears in response to acute myocardial infarction (AMI). A case of 51-year-old male with acute anterior myocardial infarction (AMI) with ST elevation has been presented. This patient on 7th day after AMI onset underwent SPECT/CT (by cardiac cadmium-zinc-telluride gamma-camera) with 99mTc-Tectrotide, cardiac MRI with gadolinium and, on 9th day after AMI, myocardial perfusion scintigraphy (MPS) at rest. Clear myocardial uptake of 99mTc-Tectrotide, predominantly in apical and intermediate anterior wall of left ventricle was detected. The uptake matched with areas of hypoperfusion (by SPECT) and myocardial injury (by MRI). This case demonstrated the applicability of technetium-99m-labeled SSTR-t radiotracers for post-infarction inflammation imaging. Currently assumed, that SSTR-t radiotracers reflect an increased number of activated macrophages infiltrating infarcted myocardium, which is not possible using any other imaging technique. Thus, potentially, SSTR scintigraphy may be useful for diagnosis and monitoring of myocardial post-infarction inflammation as well as for anti-inflammatory image-guide therapy assessment.


Subject(s)
Myocardial Infarction , Myocarditis , Male , Humans , Middle Aged , Technetium , Somatostatin , Tomography, X-Ray Computed , Myocardial Infarction/diagnostic imaging , Radionuclide Imaging , Tomography, Emission-Computed, Single-Photon/methods , Technetium Tc 99m Sestamibi , Receptors, Somatostatin , Inflammation
4.
R Soc Open Sci ; 8(3): 201986, 2021 Mar 10.
Article in English | MEDLINE | ID: mdl-33959352

ABSTRACT

For field electron emission (FE), an empirical equation for measured current I m as a function of measured voltage V m has the form I m = CV m k exp[-B/V m], where B is a constant and C and k are constants or vary weakly with V m. Values for k can be extracted (i) from simulations based on some specific FE theory, and in principle (ii) from current-voltage measurements of sufficiently high quality. This paper shows that a comparison of theoretically derived and experimentally derived k-values could provide a sensitive and useful tool for comparing FE theory and experiment, and for choosing between alternative theories. Existing methods of extracting k-values from experimental or simulated current-voltage data are discussed, including a modernized 'least residual' method, and existing knowledge concerning k-values is summarized. Exploratory simulations are reported. Where an analytical result for k is independently known, this value is reliably extracted. More generally, extracted k-values are sensitive to details of the emission theory used, but also depend on assumed emitter shape; these two influences will need to be disentangled by future research, and a range of emitter shapes will need examination. Other procedural conclusions are reported. Some scientific issues that this new tool may eventually be able to help investigate are indicated.

5.
Comput Methods Programs Biomed ; 206: 106111, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33957377

ABSTRACT

BACKGROUND AND OBJECTIVE: Lung cancer is the most common type of cancer with a high mortality rate. Early detection using medical imaging is critically important for the long-term survival of the patients. Computer-aided diagnosis (CAD) tools can potentially reduce the number of incorrect interpretations of medical image data by radiologists. Datasets with adequate sample size, annotation, and truth are the dominant factors in developing and training effective CAD algorithms. The objective of this study was to produce a practical approach and a tool for the creation of medical image datasets. METHODS: The proposed model uses the modified maximum transverse diameter approach to mark a putative lung nodule. The modification involves the possibility to use a set of overlapping spheres of appropriate size to approximate the shape of the nodule. The algorithm embedded in the model also groups the marks made by different readers for the same lesion. We used the data of 536 randomly selected patients of Moscow outpatient clinics to create a dataset of standard-dose chest computed tomography (CT) scans utilizing the double-reading approach with arbitration. Six volunteer radiologists independently produced a report for each scan using the proposed model with the main focus on the detection of lesions with sizes ranging from 3 to 30 mm. After this, an arbitrator reviewed their marks and annotations. RESULTS: The maximum transverse diameter approach outperformed the alternative methods (3D box, ellipsoid, and complete outline construction) in a study of 10,000 computer-generated tumor models of different shapes in terms of accuracy and speed of nodule shape approximation. The markup and annotation of the CTLungCa-500 dataset revealed 72 studies containing no lung nodules. The remaining 464 CT scans contained 3151 lesions marked by at least one radiologist: 56%, 14%, and 29% of the lesions were malignant, benign, and non-nodular, respectively. 2887 lesions have the target size of 3-30 mm. Only 70 nodules were uniformly identified by all the six readers. An increase in the number of independent readers providing CT scans interpretations led to an accuracy increase associated with a decrease in agreement. The dataset markup process took three working weeks. CONCLUSIONS: The developed cluster model simplifies the collaborative and crowdsourced creation of image repositories and makes it time-efficient. Our proof-of-concept dataset provides a valuable source of annotated medical imaging data for training CAD algorithms aimed at early detection of lung nodules. The tool and the dataset are publicly available at https://github.com/Center-of-Diagnostics-and-Telemedicine/FAnTom.git and https://mosmed.ai/en/datasets/ct_lungcancer_500/, respectively.


Subject(s)
Lung Neoplasms , Solitary Pulmonary Nodule , Algorithms , Diagnosis, Computer-Assisted , Humans , Lung Neoplasms/diagnostic imaging , Radiographic Image Interpretation, Computer-Assisted , Sensitivity and Specificity , Solitary Pulmonary Nodule/diagnostic imaging , Tomography, X-Ray Computed
6.
Heliyon ; 7(3): e06432, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33748490

ABSTRACT

Ulcerative colitis (UC) is an inflammatory disease that affects the colon and rectum. Recently, evidence has emerged about the influence of microbiota on the development of this disease. However, studies on the role of intestinal microbiota in the pathogenesis of UC have been incomplete. In addition, there are no comprehensive studies of the causes of ulcerative colitis and data on the microbiological composition of the intestines of patients with ulcerative colitis in Russia. We carried out a study of the microbiological composition of the intestines of patients with ulcerative colitis and healthy individuals. We found significant changes in the bacteria genera and species in patients with UC compared with the control group using sequencing on the IonTorrent PGM system and subsequent data analysis. In our study we observed a significant increase of the genus Haemophilus, Olsenella, Prevotella, Cedecea, Peptostreptococcus, Faecalibacterium, Lachnospira, Negativibacillus, Butyrivibrio, and the species Bacteroides coprocola, Phascolarctobacterium succinatutens, Dialister succinatiphilus, Sutterella wadsworthensis, Faecalibacterium prausnitzii in patients with ulcerative colitis. In addition, in patients with ulcerative colitis there was a significant decrease in the genus Fusicatenibacter, Butyricimonas, Lactococcus, Eisenbergiella, Coprobacter, Cutibacterium, Falsochrobactrum, Brevundimonas, Yersinia, Leuconostoc and in the species Fusicatenibacter saccharivorans. We found confirmation of our data with literary sources and studies of UC. In addition, we discovered a few taxa such as Negativibacillus spp. and Falsochrobactrum spp. that have not been previously found in human stool samples. Our data confirm that more research is needed to understand the role of microbiome changes in the development of UC in different people populations.

7.
Fungal Syst Evol ; 5: 99-111, 2020 Jun.
Article in English | MEDLINE | ID: mdl-32467916

ABSTRACT

Micraspis acicola was described more than 50 years ago to accommodate a phacidium-like fungus that caused a foliar disease of Picea mariana. After its publication, two more species were added, M. strobilina and M. tetraspora, all of them growing on Pinaceae in the Northern Hemisphere, but each species occupying a unique type of host tissue (needles, cones or wood). Micraspis is considered to be a member of class Leotiomycetes, but was originally placed in Phacidiaceae (Phacidiales), later transferred to Helotiaceae (Helotiales) and recently returned to Phacidiales but in a different family (Tympanidaceae). The genus remains poorly sampled, and hence poorly understood both taxonomically and ecologically. Here, we use morphology, cultures and sequences to provide insights into its systematic position in Leotiomycetes and its ecology. Our results show that the genus should not be included in Tympanidaceae or Phacidiaceae, and support the erection of a new family and order with a unique combination of morphological features supported by molecular data.

8.
Opt Express ; 28(4): 4801-4809, 2020 Feb 17.
Article in English | MEDLINE | ID: mdl-32121711

ABSTRACT

We report on an extended cavity quantum cascade laser based on a cavity resonator integrated grating filter (CRIGF) that acts as both cavity end-reflector and spectral selector. Stable, mode-hop free, single-mode emission around 2150 cm-1 is obtained over large injection current ranges (more than 50 mA) with a typical threshold around 290 mA. A digital frequency tuning over more than 65 cm-1 is obtained by changing the periodicity of the CRIGF ending the extended cavity.

9.
Opt Express ; 26(21): 27014-27020, 2018 Oct 15.
Article in English | MEDLINE | ID: mdl-30469777

ABSTRACT

Cavity Resonator Grating Filters (CRIGFs) working in the Mid-Infrared are reported, with narrow-band resonant reflectivity peaks around 2200 cm-1 (4.6 µm). They are fabricated in the GaAs/AlGaAs material system that can potentially cover the whole [1-12] µm spectral range. TE-polarized peak reflectivity is 30% with a 4 cm-1 full width at half maximum.

10.
Georgian Med News ; (285): 63-69, 2018 Dec.
Article in Russian | MEDLINE | ID: mdl-30702072

ABSTRACT

Aim - to assess the nature and three-year dynamics of structural and functional changes in the cardiovascular system in relation to the levels of enzymatic and non-enzymatic antioxidants in chronic coronary heart disease in men. The study included 246 men aged 48 to 65 years (mean age 58 years (53,0; 63,0)) with stable form of ischemic heart disease - angina FC II-III CHF I-III FC (NYHA), observed during 2012-2015. To assess the level of oxidative stress in all patients by ELISA was determined by lipid peroxide, total antioxidant status (CCA) and levels of non-enzymatic antioxidant bilirubin (BR). Patients were divided into 2 groups according to the level of serum BR: the main group - 146 patients with the level of BR< 8.0 µmol/l; the control group-100 patients with the level of BR ≥8.0 µmol/l. Assessment of the structural and functional state of the myocardium included ECG, XM ECG, EchoCG, VEM test. A decrease in the level of protection against oxidative stress (OS) in men with stable CHD in the form of a significant increase in the level of lipid peroxides and a decrease in the OAS index was found. In the study group OxyStat, total cholesterol and LDL cholesterol were significantly higher (p<0.01)., and ImAnOx - significantly lower than in the control group (p<0.01). A high degree of direct relationship between the level of blood BR and the indicator of AOC is established. Three-year dynamic observation showed a close relationship between the processes of cardiovascular system remodeling and OS components. The high level of OS in men with stable ischemic heart disease is accompanied by adverse changes in the geometry of the left ventricle (eccentric non-dilatated hypertrophy, an increase in the number of segments with hypokinesis), which leads to the progression of chronic heart failure with the risk of ischemic and arrhythmic reactions to physical activity.


Subject(s)
Bilirubin/blood , Hypertrophy, Left Ventricular/metabolism , Lipid Peroxides/blood , Myocardial Ischemia/metabolism , Myocardium/metabolism , Oxidative Stress , Antioxidants/metabolism , Case-Control Studies , Chronic Disease , Echocardiography , Electrocardiography , Humans , Hypertrophy, Left Ventricular/blood , Hypertrophy, Left Ventricular/etiology , Hypertrophy, Left Ventricular/pathology , Male , Middle Aged , Myocardial Ischemia/blood , Myocardial Ischemia/complications , Myocardial Ischemia/pathology , Myocardium/pathology , Ventricular Remodeling
11.
Persoonia ; 41: 18-38, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30728597

ABSTRACT

Glutinoglossum is one of the earth tongue genera with viscid or glutinous ascocarps. Based on morphology and ITS1-5.8S-ITS2, nrLSU and tef1 sequence data, seven new species are described: G. circinatum, G. lumbricale, G. orientale, G. peregrinans, G. proliferatum, G. pseudoglutinosum, and G. triseptatum. The lectotypes for Geoglossum glutinosum var. lubricum and for Geoglossum glabrum var. majus as well as the epitype for Glutinoglossum glutinosum are designated. The comprehensive morphological study of G. heptaseptatum resulted in the discovery of ascospores germinating by conidia inside the asci, which is first noted for Glutinoglossum species. The status of Cibalocoryne is discussed.

12.
J Opt Soc Am A Opt Image Sci Vis ; 34(2): 234-240, 2017 Feb 01.
Article in English | MEDLINE | ID: mdl-28157849

ABSTRACT

We design a narrowband polarization independent transmission guided mode resonance filter whose center wavelength is tunable with respect to the angle of incidence. The device is composed of two identical structures assembled back to back. Each half structure is a dielectric multilayer stack in which a grating is engraved. This so-called 2×1D crossed gratings component has already been demonstrated for reflection filtering [Opt. Lett.36, 1662 (2011)OPLEDP0146-959210.1364/OL.36.001662; Opt. Lett.39, 6038 (2014)OPLEDP0146-959210.1364/OL.39.006038]. The functioning in transmission requires the use of a high index material for the grating bumps. For the design, we resort to a clustering global optimization algorithm, used for the first time to our knowledge for grating structures. We demonstrated two filters with a quality factor of about 4000, tunable over more than 15 nm when the angle of incidence varies over a range of 4°, and with a transmittivity at resonance greater than 95% whatever the incident polarization.

13.
Persoonia ; 36: 316-458, 2016 Jun.
Article in English | MEDLINE | ID: mdl-27616795

ABSTRACT

Novel species of fungi described in the present study include the following from Australia: Vermiculariopsiella eucalypti, Mulderomyces natalis (incl. Mulderomyces gen. nov.), Fusicladium paraamoenum, Neotrimmatostroma paraexcentricum, and Pseudophloeospora eucalyptorum on leaves of Eucalyptus spp., Anungitea grevilleae (on leaves of Grevillea sp.), Pyrenochaeta acaciae (on leaves of Acacia sp.), and Brunneocarpos banksiae (incl. Brunneocarpos gen. nov.) on cones of Banksia attenuata. Novel foliicolous taxa from South Africa include Neosulcatispora strelitziae (on Strelitzia nicolai), Colletotrichum ledebouriae (on Ledebouria floridunda), Cylindrosympodioides brabejum (incl. Cylindrosympodioides gen. nov.) on Brabejum stellatifolium, Sclerostagonospora ericae (on Erica sp.), Setophoma cyperi (on Cyperus sphaerocephala), and Phaeosphaeria breonadiae (on Breonadia microcephala). Novelties described from Robben Island (South Africa) include Wojnowiciella cissampeli and Diaporthe cissampeli (both on Cissampelos capensis), Phaeotheca salicorniae (on Salicornia meyeriana), Paracylindrocarpon aloicola (incl. Paracylindrocarpon gen. nov.) on Aloe sp., and Libertasomyces myopori (incl. Libertasomyces gen. nov.) on Myoporum serratum. Several novelties are recorded from La Réunion (France), namely Phaeosphaeriopsis agapanthi (on Agapanthus sp.), Roussoella solani (on Solanum mauritianum), Vermiculariopsiella acaciae (on Acacia heterophylla), Dothiorella acacicola (on Acacia mearnsii), Chalara clidemiae (on Clidemia hirta), Cytospora tibouchinae (on Tibouchina semidecandra), Diaporthe ocoteae (on Ocotea obtusata), Castanediella eucalypticola, Phaeophleospora eucalypticola and Fusicladium eucalypticola (on Eucalyptus robusta), Lareunionomyces syzygii (incl. Lareunionomyces gen. nov.) and Parawiesneriomyces syzygii (incl. Parawiesneriomyces gen. nov.) on leaves of Syzygium jambos. Novel taxa from the USA include Meristemomyces arctostaphylos (on Arctostaphylos patula), Ochroconis dracaenae (on Dracaena reflexa), Rasamsonia columbiensis (air of a hotel conference room), Paecilomyces tabacinus (on Nicotiana tabacum), Toxicocladosporium hominis (from human broncoalveolar lavage fluid), Nothophoma macrospora (from respiratory secretion of a patient with pneumonia), and Penidiellopsis radicularis (incl. Penidiellopsis gen. nov.) from a human nail. Novel taxa described from Malaysia include Prosopidicola albizziae (on Albizzia falcataria), Proxipyricularia asari (on Asarum sp.), Diaporthe passifloricola (on Passiflora foetida), Paramycoleptodiscus albizziae (incl. Paramycoleptodiscus gen. nov.) on Albizzia falcataria, and Malaysiasca phaii (incl. Malaysiasca gen. nov.) on Phaius reflexipetalus. Two species are newly described from human patients in the Czech Republic, namely Microascus longicollis (from toenails of patient with suspected onychomycosis), and Chrysosporium echinulatum (from sole skin of patient). Furthermore, Alternaria quercicola is described on leaves of Quercus brantii (Iran), Stemphylium beticola on leaves of Beta vulgaris (The Netherlands), Scleroderma capeverdeanum on soil (Cape Verde Islands), Scleroderma dunensis on soil, and Blastobotrys meliponae from bee honey (Brazil), Ganoderma mbrekobenum on angiosperms (Ghana), Geoglossum raitviirii and Entoloma kruticianum on soil (Russia), Priceomyces vitoshaensis on Pterostichus melas (Carabidae) (Bulgaria) is the only one for which the family is listed, Ganoderma ecuadoriense on decaying wood (Ecuador), Thyrostroma cornicola on Cornus officinalis (Korea), Cercophora vinosa on decorticated branch of Salix sp. (France), Coprinus pinetorum, Coprinus littoralis and Xerocomellus poederi on soil (Spain). Two new genera from Colombia include Helminthosporiella and Uwemyces on leaves of Elaeis oleifera. Two species are described from India, namely Russula intervenosa (ectomycorrhizal with Shorea robusta), and Crinipellis odorata (on bark of Mytragyna parviflora). Novelties from Thailand include Cyphellophora gamsii (on leaf litter), Pisolithus aureosericeus and Corynascus citrinus (on soil). Two species are newly described from Citrus in Italy, namely Dendryphiella paravinosa on Citrus sinensis, and Ramularia citricola on Citrus floridana. Morphological and culture characteristics along with ITS nrDNA barcodes are provided for all taxa.

14.
Opt Lett ; 41(10): 2358-61, 2016 May 15.
Article in English | MEDLINE | ID: mdl-27177002

ABSTRACT

The rigorous modeling of large (hundreds of wavelengths) optical resonant components patterned at a subwavelength scale remains a major issue, especially when long range interactions cannot be neglected. In this Letter, we compare the performances of the discrete dipole approximation approach to that of the Fourier modal, the finite element and the finite difference time domain methods, for simulating the spectral behavior of a cavity resonator integrated grating filter (CRIGF). When the component is invariant along one axis (two-dimensional configuration), the four techniques yield similar results, despite the modeling difficulty of such a structure. We also demonstrate, for the first time to the best of our knowledge, the rigorous modeling of a three-dimensional CRIGF.

15.
Vopr Pitan ; 85(6): 57-63, 2016.
Article in Russian | MEDLINE | ID: mdl-29376309

ABSTRACT

The results of investigation of alimentary correction of lipid metabolism under the admin­istration of processed products from wheat germ - oil (with the content of policosanol at least 1.5-8.0 mg/100 g, vitamin E - 180-200 mg/100 g, PUFA - 60-65%) and cake flour (with the content of protein - 30-35%, oil with analogue composition -5-7%, digestible carbohydrates - 45-47%, fiber - 18-26%, vitamins B1, B3, B6, B9, E, PP, minerals and trace elements - Zn, Mn, K, Fe, Se, P) are presented. Volunteers among teachers and students of the university aged 16 to 65 years daily consumed wheat germ oil obtained by cold pressing in an amount of 3.5 g, regardless of the meal within 30 days. Then a part of them (30 persons) consumed daily 50 g of oil cake obtained after pressing oil, which provided the intake of the same amount of oil (3.5 g). Lipid metabolism param­eters were monitored in experiment participants before receiving the processed products of wheat germ, after germ meal intake and beyond 30 and 60 days after consumption of wheat germ. Data analysis was carried out on three age groups: 16-24, 25-44 and 45- 65 years. All participants of the experiment showed a reduction in total cholesterol level by 6-8%, increasing the concentration of HDL cholesterol by 3-24%, lowering LDL cholesterol concentrations by 4-21%, reduction of triglyceride concentration by 12-24%, a positive correction of atherogenic factor values by for 10-25%. Prolonged action of the investigated foods was established: lipid metabolism parameters in the tested group were better than in the control group after 30 days of intake discontinuation of oil or wheat germ flour, the positive adjustment effect disappeared 60 days after consuming the products. The findings demonstrate a positive effect on the normalization of lipid metabolism when cake flour of wheat germ was administered in daily food ration, similar to the effect of oil intake, which is important for the prevention of cardiovascular diseases and atherosclerosis. Given the significant production of cake flour of wheat germ (up to 90-95% of the raw material) and its not high cost as a secondary biological resource, this product can be recommended to the introduction in the diet of organized groups, including socially vulnerable groups.


Subject(s)
Flour , Lipid Metabolism/drug effects , Plant Oils/administration & dosage , Triticum , Adolescent , Adult , Aged , Female , Humans , Male , Middle Aged , School Teachers , Students
16.
J Opt Soc Am A Opt Image Sci Vis ; 32(3): 420-30, 2015 Mar 01.
Article in English | MEDLINE | ID: mdl-26366653

ABSTRACT

The extraordinary flattening of the dispersion curve of the so-called cavity resonator integrated guided-mode resonance filters (CRIGFs) is analyzed and explained as due to the intramode coupling imposed by the external Bragg resonators. CRIGFs are composed of a grating coupler (guided-mode resonance filter, GMRF) put between two distributed Bragg reflectors (DBRs). They form a cavity box in which the excited guided mode is confined. This confinement provides resonances with small spectral width (smaller than 1 nm for optical wavelengths) and extraordinary wide angular acceptance (several degrees). At a first glance, one may think that similar performances could be obtained while putting the GMRF and the DBR one above the other, forming a so-called "doubly periodic" grating, as in this configuration also the DBR confines the mode. Yet, the angular acceptance of CRIGFs is an order of magnitude greater than in classical gratings, even with complex pattern. The aim of the present paper is to identify the phenomenon responsible for the extraordinary large angular acceptance of CRIGFs. We numerically calculate, for the first time to the best of our knowledge, the dispersion curve of the mode excited in the CRIGF. The dispersion curve shows a flat part, where the resonance wavelength is quasi-independent of the angle of incidence, and the flattening grows with the width of the Bragg reflector. We develop an approximate coupled four-wave model, which predicts the extraordinary flattening as a consequence of an additional coupling of the waveguide modes of the GMRF provided by the Bragg grating, that does not exist in the "doubly periodic" gratings.

17.
Opt Express ; 23(9): 11687-701, 2015 May 04.
Article in English | MEDLINE | ID: mdl-25969260

ABSTRACT

This paper is devoted to the study of the transmission properties of Slanted Annular Aperture Arrays made in perfectly conducting metal. More precisely, we consider the transmission based on the excitation of the cutoff-less guided mode, namely the TEM mode. We numerically and analytically demonstrate some intrinsic properties of the structure showing a transmission coefficient of at least 50% of an unpolarized incident beam independently of the illumination configuration (angle and plane of incidence). The central symmetry exhibited by the structure is analytically exploited to demonstrate the existence of a polarization state for which all the incident energy is transmitted through the sub-wavelength apertures when the eigenmode is excited, whatever are the illumination and the geometrical parameters. For this state of polarization, the laminar flow of the energy through the structure can exhibit giant deviation over very small distances. An example of energy flow deviation of 220° per wavelength is presented for illustration. The results presented in this paper could be considered as an important contribution to the understanding of the enhanced transmission phenomenon based on the excitation of guided modes.

18.
Gig Sanit ; 94(9): 42-6, 2015.
Article in Russian | MEDLINE | ID: mdl-27029168

ABSTRACT

There were obtained data which confirm the increase of efficiency of gas exchange processes in students and teachers of the engineering high school in the daily use of at least 3.5 g of wheat germ oil and 50 g of wheat germ cake flour without the correction of the basic ration. The study of the exhaled gas-air mixture showed in all age groups the gain in the concentration of carbon dioxide and the decline of concentration of oxygen by the 0.20-0.30%. There was established the increase of blood oxygenation level in all subjects. There was demonstrated the relationship between the depth of the alteration of these parameters with age, and regular physical activity in studied cases.


Subject(s)
Energy Metabolism/physiology , Faculty , Flour , Health Status , Nutritional Status/physiology , Plant Oils/pharmacology , Schools , Students , Female , Humans , Male
19.
Appl Opt ; 54(35): 10359-68, 2015 Dec 10.
Article in English | MEDLINE | ID: mdl-26836859

ABSTRACT

Plasmonic resonances in metallic nanoparticles are exploited to create efficient optical filtering functions. A finite element method is used to model metallic nanoparticle gratings. The accuracy of this method is shown by comparing numerical results with measurements on a two-dimensional grating of gold nanocylinders with an elliptic cross section. A parametric analysis is then performed in order to design efficient filters with polarization dependent properties together with high transparency over the visible range. The behavior of nanoparticle gratings is also modeled using the Maxwell-Garnett homogenization theory and analyzed by comparison with the diffraction of a single nanoparticle. The proposed structures are intended to be included in optical systems that could find innovative applications.


Subject(s)
Metal Nanoparticles , Surface Plasmon Resonance/instrumentation , Equipment Design , Finite Element Analysis , Optical Devices , Optical Phenomena
20.
Langmuir ; 30(33): 9985-90, 2014 Aug 26.
Article in English | MEDLINE | ID: mdl-25084807

ABSTRACT

The structure of deterministically nanopatterned surfaces created using a combination of electron beam lithography and reactive ion etching was evaluated using small-angle neutron scattering (SANS). Samples exhibit 2D neutron scattering patterns that confirm the presence of ordered nanoscale cavities consistent with the targeted morphologies as well as with SEM data analysis. Comparison of SANS intensities obtained from samples in air and in contact with an aqueous phase (pure deuterium oxide, D2O, or a contrast matched mixture of D2O + H2O) reveals formation of stable gaseous nanobubbles trapped inside the cavities. The relative volume of nanobubbles depends strongly on the hydrophobicity of the cavity walls. In the case of hydrophobic surfaces, nanobubbles occupy up to 87% of the total cavity volume. The results demonstrate the high degree of sensitivity of SANS measurements for detecting and characterizing nano- and mesoscale bubbles with the volume fraction as low as ∼10(-6).

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