Nm For Type Research Articles

Tunability of plasmonic resonances in stratified hyperbolic metamaterials

We numerically and experimentally demonstrate the tunability of plasmonic resonances in the spectral range from 550 nm to 900 nm for type II hyperbolic metamaterials, as a function of their number of layers, period, and filling fraction. The type II hyperbolic metamaterial consisted of stratified periodic arrays of gold and titanium dioxide thin layers on top of a glass substrate. Through numerical and experimental characterization of the totally internally reflected spectra as a function of incidence angle, we show that the tunability of the plasmonic resonance mainly depends on the filling fraction, while the number of layers and the period of the structure only affect the contrast of attenuated reflected spectra. In addition to demonstrating the capability of tuning plasmonic resonances in simplistic stratified mediums, this work contributes to the understanding of light interaction with hyperbolic metamaterials for the improvement of optical devices for sensing applications.

On the Multi-Functional Behavior of Graphene-Based Nano-Reinforced Polymers.

The objective of the present study is the assessment of the impact performance and the concluded thermal conductivity of epoxy resin reinforced by layered Graphene Nano-Platelets (GNPs). The two types of used GNPs have different average thicknesses, <4 nm for Type 1 and 9–12 nm for Type 2. Graphene-based polymers containing different GNP loading contents (0.5, 1, 5, 10, 15 wt.%) were developed by using the three-roll mill technique. Thermo-mechanical (Tg), impact tests and thermal conductivity measurements were performed to evaluate the effect of GNPs content and type on the final properties of nano-reinforced polymers. According to the results, thinner GNPs were proven to be more promising in all studied properties when compared to thicker GNPs of the same weight content. More specifically, the glass transition temperature of nano-reinforced polymers remained almost unaffected by the GNPs inclusion. Regarding the impact tests, it was found that the impact resistance of the doped materials increased up to 50% when 0.5 wt.% Type 1 GNPs were incorporated within the polymer. Finally, the thermal conductivity of doped polymers with 15 wt.% GNPs showed a 130% enhancement over the reference material.

Remotely estimating total suspended solids concentration in clear to extremely turbid waters using a novel semi-analytical method

Total suspended solids (TSS) concentration is an important biogeochemical parameter for water quality management and sediment-transport studies. In this study, we propose a novel semi-analytical method for estimating TSS in clear to extremely turbid waters from remote-sensing reflectance (Rrs). The proposed method includes three sub-algorithms used sequentially. First, the remotely sensed waters are classified into clear (Type I), moderately turbid (Type II), highly turbid (Type III), and extremely turbid (Type IV) water types by comparing the values of Rrs at 490, 560, 620, and 754 nm. Second, semi-analytical models specific to each water type are used to determine the particulate backscattering coefficients (bbp) at a corresponding single wavelength (i.e., 560 nm for Type I, 665 nm for Type II, 754 nm for Type III, and 865 nm for Type IV). Third, a specific relationship between TSS and bbp at the corresponding wavelength is used in each water type. Unlike other existing approaches, this method is strictly semi-analytical and its sub-algorithms were developed using synthetic datasets only. The performance of the proposed method was compared to that of three other state-of-the-art methods using simulated (N = 1000, TSS ranging from 0.01 to 1100 g/m3) and in situ measured (N = 3421, TSS ranging from 0.09 to 2627 g/m3) pairs of Rrs and TSS. Results showed a significant improvement with a Median Absolute Percentage Error (MAPE) of 16.0% versus 30.2–90.3% for simulated data and 39.7% versus 45.9–58.1% for in situ data, respectively. The new method was subsequently applied to 175 MEdium Resolution Imaging Spectrometer (MERIS) and 498 Ocean and Land Colour Instrument (OLCI) images acquired in the 2003–2020 timeframe to produce long-term TSS time-series for Lake Suwa and Lake Kasumigaura, Japan. Performance assessments using MERIS and OLCI matchups showed good agreements with in situ TSS measurements.

Numerical Investigation of High-Purity Entangled Photon-Pair Generation in Ba3Mg3(BO3)3F3 Crystals

We investigate the high-purity entangled photon pair generation in a recently developed borate crystal, Ba3Mg3(BO3)3F3. The technique is based on the spontaneous parametric down-conversion under the extended phase matching (EPM), where the phase matching and the group velocity matching between the interacting photons are satisfied simultaneously in bulk crystals with point symmetry of orthorhombic mm2 (thus showing biaxial birefringence). We will discuss all the theoretical aspects required for the generation of photon pairs in mm2 biaxial crystals, which are much more complex than the cases of uniaxial crystals (e.g., β-BaB2O4 and LiNbO3) and periodically poled crystals that are widely used in the field. Our study includes theoretical and numerical investigations of two types of EPM and their corresponding effective nonlinearities and spatial walk-offs. The results show that two types of EPM are satisfied over the specific range in the direction of pump wave vector, corresponding to its spectral ranges of 876.15–1052.77 nm for Type I and 883.92–914.33 nm for Type II. The joint spectral analyses show that photon-pairs can be generated with high purities of 0.997 with a proper pump filtering (for Type II), and 0.833 even without pump filtering (for Type I).

Competitive binding of monoclonal antibody monomer-dimer mixtures on ceramic hydroxyapatite

The internal structure of ceramic hydroxyapatite CHT Type I and Type II and the adsorption behavior of a monoclonal antibody in monomeric and dimeric forms are determined. Both CHT types contain elongated nanocrystals with size about 20 x 100 nm for Type I and about 50 x 200 nm for Type II. Internal porosities and apparent pore radii based on inverse size exclusion chromatography are 0.73 and 30 nm for Type I and 0.70 and 49 nm for Type II. Adsorption isotherms show maximum capacities of 95 and 110 mg/mL of particle for monomer and dimer on Type I and of 55 and 67 mg/mL of particle on Type II, in approximate agreement with the ratio of surface areas. The isotherms are dependent on the Na+ concentration consistent with an electrostatically driven mechanism. Mixture adsorption shows selectivity toward the dimer, with mean α-values of 4.3 and 5.8 for Type I and II, respectively. Effective pore diffusivities for non-binding conditions are 0.54 × 10−7 and 0.33 × 10−7 cm2/s for monomer and dimer in CHT Type I increasing to 0.94 × 10−7 and 0.66 × 10−7 cm2/s as a result of the larger pore size of Type II. Effective pore diffusivities for strong binding conditions, obtained by confocal microscopy, are much smaller than the non-binding values for Type I but essentially the same for Type II, indicating that diffusional hindrance by the bound protein is greater in the smaller pores of Type I. Mixture confocal adsorption experiments show that the competitive binding kinetics is largely controlled by pore diffusion in both CHT types with the dimer readily displacing the monomer even for strong binging conditions, but is much faster on Type II.

Rapid and Sensitive Detection of the Interaction of Human Papillomavirus Virus-Like Particles with Yeast Whole Cell RNA Using Biolayer Interferometry.

RNA is a potential contaminant encountered in the production of recombinant yeast products such as proteins and virus-like particles (VLPs) and can be a particular concern when RNA associates with the product of interest. In this study a method to monitor and quantify the interaction of RNA with yeast-expressed human papillomavirus (HPV) VLPs using biolayer interferometry (BLI) is developed. Both biosensors with immobilized VLPs as well as biosensors with immobilized RNA are tested. Two types of recombinantly expressed HPV VLPs are used, Type 18 and Type 11. The data show that yeast whole cell RNA associates with Type 18 but not with Type 11 (maximum binding signal of 0.20 ± 0.02 nm on immobilized VLP probes for Type 18 vs. 0.03 ± 0.01 nm for Type 11). Additionally, the results show that a higher ionic strength weakens the affinity by both decreasing the association rate and increasing the dissociation rate, resulting in the dissociation constant increasing from 0.48 × 10-9 to 2.1 × 10-9 M, with phosphate ions having a greater effect on the reduction of association compared to chloride ions.

Measurement of wavelength-dependent second order susceptibility tensor elements in types I and II collagens

In this work, we measured the second order susceptibility (SOS) tensor ratios of χzzz/χzxx and χxzx/χzxx between 725–875 nm in type I (rat tail tendon) and II (rat trachea) collagen. In this wavelength range, χzzz/χzxx and χxzx/χzxx were found to be frequency-independent. Specifically, χzzz/χzxx and χxzx/χzxx are around 1.4 and 0.7 for collagen I; 1.2 and 0.4 for collagen II, respectively. Therefore, the near-infrared wavelength range of 700–800 nm is sufficiently far from the collagen resonance at 247 nm in order for the SOS tensor ratios to be wavelength independent. Our results suggest that microscopy imaging based on the use of SOS as a contract mechanism can use the simultaneous illumination of different excitation wavelengths with different polarizations for faster implementation of second order susceptibility microscopy.

Derivation of absorption coefficient and reduced scattering coefficient with edge-loss method and comparison with video reflectometry method

We derived the absorption coefficient (μa) and the reduced scattering coefficient (μs′) using the edge-loss method (ELM) and the video reflectometry method (VRM), and compared the results. In a previous study, we developed the ELM to easily evaluate the lateral spread in the skin; the VRM is a conventional method. The ELM measures the translucency index, which is correlated with μa and μs′. To obtain a precise estimation of these parameters, we improved the treatment of a white standard and the surface reflection. For both skin phantoms and actual skin, the values for μa and μs′ that we obtained using the ELM were similar to those obtained using the VRM, when μa/μs′ was less than or equal to 0.05 and the diffusion approximation was applicable. Under this condition, the spectral reflectivity is greater than 0.4. In this study, we considered wavelengths longer than 600 nm for Types III and IV of the Fitzpatrick scale. For skin, the repeatability errors of the parameters obtained with the ELM were smaller than those obtained with the VRM; this can be an advantage in field tests.

Growth and optical properties of K2(Al0.71Ga0.29)2B2O7 crystal

Crystals of K2(Al0.71Ga0.29)2B2O7 (KAGBO) with dimensions up to 20×15×10mm3 have been grown with NaF flux by the top-seeded solution growth method. The structure of KAGBO crystal is analog to its parent compound K2Al2B2O7 and belongs to the space group P321 with cell parameters of a=8.5700(12) Å and c=8.524(3) Å. Both theoretical calculation based on the structure and powder second-harmonic generation (SHG) test reveal that KAGBO has a slight smaller SHG coefficient d11 as that of KABO or KH2PO4 (KDP). KAGBO crystal also shows a wide transparency range from 189 to 3000nm and its measured refractive indices indicate that KAGBO can be phase matched to 234.7nm for type I SHG.

Defects of the structure of semiconductor superlattices grown on the basis of II–VI alloys

The specific features of defects of crystal lattices in multilayer device structures containing small-period (T ≲ 20 nm) superlattices of type I ZnSe/Cd x Zn1 − x Se/ZnSe/.../ZnSe/(001)GaAs and type II ZnS/ZnSe1 − x S x /ZnS/.../ZnS/(001)GaAs are studied by the methods of X-ray diffractometry and diffraction rocking pseudocurves, and partially by the X-ray topography. According to the data of quantitative analysis of the X-ray diffraction spectra, the periods of superlattices are in the range T I = 11.3–16.1 nm (for the compositions Cd x Zn1 − x Se with x 1 = 0.047 and x 2 = 0.107) for type I superlattices and T II = 15.6–17.2 nm for type II superlattices (for the compositions ZnSe1 − x S x with x 1 = 0.20 and x 2 = 0.10). The widths of diffraction peaks from both the ZnSe layers and small-period superlattices in the diffraction rocking pseudocurves considerably exceed their widths in the X-ray diffraction spectra. This fact proves that a pronounced plastic strain with the formation of series of rectilinear dislocations in the crossing slip systems took place in the studied device structures. In order to exclude the generation of dislocations in the growth processes, it is necessary to decrease the concentration of the solid solution to the values x < 0.047 for the first type of superlattices and to the values x ≲ 0.062 for the second type of superlattices, and to decrease the thickness of the ZnSe and ZnS layers.

Potassium depolarization of mammalian vestibular sensory cells increases [Ca2+]i through voltage-sensitive calcium channels.

The existence of voltage-sensitive Ca2+ channels in type I vestibular hair cells of mammals has not been conclusively proven. Furthermore, Ca2+ channels present in type II vestibular hair cells of mammals have not been pharmacologically identified. Fura-2 fluorescence was used to estimate, in both cell types, intracellular Ca2+ concentration ([Ca2+]i) variations induced by K+ depolarization and modified by specific Ca2+ channel agonists and antagonists. At rest, [Ca2+]i was 90 +/- 20 nM in both cell types. Microperifusion of high-K+ solution (50 mM) for 1 s increased [Ca2+]i to 290 +/- 50 nM in type I (n = 20) and to 440 +/- 50 nM in type II cells (n = 10). In Ca2+-free medium, K+ did not alter [Ca2+]i. The specific L-type Ca2+ channel agonist, Bay K, and antagonist, nitrendipine, modified in a dose-dependent manner the K+-induced [Ca2+]i increase in both cell types with maximum effect at 2 microM and 400 nM, respectively. Ni2+, a T-type Ca2+ channel blocker, reduced K+-evoked Ca2+ responses in a dose-dependent manner. For elevated Ni2+ concentrations, the response was differently affected by Ni2+ alone, or combined to nitrendipine (500 nM). In optimal conditions, nitrendipine and Ni2+ strongly depressed by 95% the [Ca2+]i increases. By contrast, neither omega-agatoxin IVA (1 microM), a specific P- and Q-type blocker, nor omega-conotoxin GVIA (1 microM), a specific N-type blocker, affected K+-evoked Ca2+i responses. These results provide the first direct evidence that L- and probably T-type channels control the K+-induced Ca2+ influx in both types of sensory cells.

Quantitation of 3-Deoxyglucosone Levels in Human Plasma

3-Deoxyglucosone (3DG), a reactive dicarbonyl, is an important intermediate in the formation of advanced glycation end products (AGEs). The AGEs are particularly important in diabetes since they have been correlated with the development of diabetic complications. Consequently, measurements of 3DG are likely to provide valuable insights into the role of this metabolite in the etiology of diabetic complications. While several methods of 3DG quantitation in human plasma have been previously published, a significant discrepancy (over 30-fold) exists in the reported values. Knechtet al.(Arch. Biochem. Biophys.294, 130–137, 1992) have reported the levels of plasma 3DG in normoglycemics to be 61 nm, using a GC/MS procedure. In contrast to this, Niwaet al.(Biochem. Biophys. Res. Commun.196, 837–843, 1993) reported 3DG levels to be 1800 nmin normoglycemics, using a totally independent GC/MS method. To resolve this disagreement and fill the need for a robust assay for this dicarbonyl, suitable for absolute quantitation, a GC/MS procedure was devised for its measurement. Plasma samples were deproteinized either by ultrafiltration or by addition of ethanol as described by Niwaet al.(Biochem. Biophys. Res. Commun.196, 837–843, 1993). 3DG in the ultrafiltrate or the supernatant was conjugated with 2,3-diaminonaphthalene to produce a stable adduct which was then converted to a silyl ether and analyzed by GC/MS. The analyte was monitored by selected ion monitoring at anm/zof 295 and 306 and quantitated using an internal standard of [U-13C]3DG. Using this approach, 3DG levels in plasma deproteinized by ultrafiltration were found to be significantly elevated from 58.5 ± 14 (SD) nmin normoglycemics to 98.5 ± 34 (SD) nmin type I diabetics. When deproteinization of the plasma was carried out using ethanol, the levels of 3DG from normoglycemic plasma were similar to those reported by Niwaet al.(1710 ± 750 (SD) nm). These results suggest that 3DG levels measured by ultrafiltration may represent the free circulating 3DG and those obtained by ethanol extraction may represent aform of 3DG bound to a macromolecule (presumbaly protein).

Second-harmonic generation under phase-velocity and group-velocity mismatch: influence of cascading self-phase and cross-phase modulation

Temporal and spectral characteristics of pulses resulting from second-harmonic generation of 120-fs amplified Ti:sapphire laser pulses up to 0.1 mJ at a wavelength of 815 nm in type I KDP crystal were experimentally and theoretically analyzed. Widely different behaviors were observed, according to the sign of the phase mismatch. Comparison between the theoretical simulation and experimental data demonstrates that the competition between third- and second-order nonlinear phenomena strongly modifies the structure of the pulses generated.

Signal transduction for chemotaxis and haptotaxis by matrix molecules in tumor cells.

Transduction of signals initiating motility by extracellular matrix (ECM) molecules differed depending on the type of matrix molecule and whether the ligand was in solution or bound to a substratum. Laminin, fibronectin, and type IV collagen stimulated both chemotaxis and haptotaxis of the A2058 human melanoma cell line. Peak chemotactic responses were reached at 50-200 nM for laminin, 50-100 nM for fibronectin, and 200-370 nM for type IV collagen. Checkerboard analysis of each attractant in solution demonstrated a predominantly directional (chemotactic) response, with a minor chemokinetic component. The cells also migrated in a concentration-dependent manner to insoluble step gradients of substratum-bound attractant (haptotaxis). The haptotactic responses reached maximal levels at coating concentrations of 20 nM for laminin and type IV collagen, and from 30 to 45 nM for fibronectin. Pretreatment of cells with the protein synthesis inhibitor, cycloheximide (5 micrograms/ml), resulted in a 5-30% inhibition of both chemotactic and haptotactic responses to each matrix protein, indicating that de novo protein synthesis was not required for a significant motility response. Pretreatment of cells with 50-500 micrograms/ml of synthetic peptides containing the fibronectin cell-recognition sequence GRGDS resulted in a concentration-dependent inhibition of fibronectin-mediated chemotaxis and haptotaxis (70-80% inhibition compared to control motility); negative control peptide GRGES had only a minimal effect. Neither GRGDS nor GRGES significantly inhibited motility to laminin or type IV collagen. Therefore, these results support a role for the RGD-directed integrin receptor in both types of motility response to fibronectin. After pretreatment with pertussis toxin (PT), chemotactic responses to laminin, fibronectin, and type IV collagen were distinctly different. Chemotaxis to laminin was intermediate in sensitivity; chemotaxis to fibronectin was completely insensitive; and chemotaxis to type IV collagen was profoundly inhibited by PT. In marked contrast to the inhibition of chemotaxis, the hepatotactic responses to all three ligands were unaffected by any of the tested concentrations of PT. High concentrations of cholera toxin (CT; 10 micrograms/ml) or the cAMP analogue, 8-Br-cAMP (0.5 mM), did not significantly affect chemotactic or haptotactic motility to any of the attractant proteins, ruling out the involvement of cAMP in the biochemical pathway initiating motility in these cells. The sensitivity of chemotaxis induced by laminin and type IV collagen, but not fibronectin, to PT indicates the involvement of a PT-sensitive G protein in transduction of the signals initiating motility to soluble laminin and type IV collagen.(ABSTRACT TRUNCATED AT 400 WORDS)

Cytoplasmic and nuclear uptake of aldosterone in toad bladder: a mathematical modeling approach.

The mechanism of aldosterone uptake in the epithelial cells of toad bladder was studied using mathematical modeling. Two complementary approaches were used. The first involved analysis of cytosolic aldosterone binding at steady state according to models defined by the sum of independent noninteractive binding sites. The best model describing the experimental data corresponded to two specific binding sites with mean dissociation constant values of 0.20 and 60 nM for types 1 and 2, respectively. The second approach was based on the analysis of cytoplasmic and nuclear aldosterone uptake kinetics at 25 and 0 degrees C in intact bladder. Two models (A and B) were studied. They both implied the existence of two types of aldosterone binding sites as precursors of the corresponding chromatin bound complexes. In model A, nuclear translocation of the two types of receptors was assumed to obey first-order kinetics. In model B, the translocation process for type 1 sites involved a time lag leading to delayed binding to chromatin. Both models were found to fit the experimental data satisfactorily. The fit obtained for model B appeared to be better at low aldosterone concentrations.

Iodothyronine deiodination reaction types in several rat tissues: effects of age, thyroid status, and glucocorticoid treatment.

Two types of iodothyronine 5'-deiodination have been characterized previously in rat tissues. They can be distinguished by inhibition of type I but not type II by 6-n-propylthiouracil, by the relative suitability of T4 and rT3 as substrates, rT3 much better than T4 for type I and T4 as good as, or better than, rT3 for type II, and by the concentration of T4 required to inhibit deiodination of rT3, 1-10 microM for type I and 1-10 nM for type II. Type I activity (6-n-propylthiouracil sensitive) is most abundant in liver and kidney. Type II activity has, to date, been identified only in the pituitary, central nervous system, and brown adipose tissue. Iodothyronine tyrosyl deiodination has also been identified in homogenates of rat brain, liver, and placenta. It is not clear how many different enzymes carry out this latter reaction. In the present studies, we have extended previous work by determining maturational patterns of the deiodinating pathways in several thyroid hormone-responsive rat tissues, possible modulation of those patterns by glucocorticoids, and the age of onset of responsivity of the deiodinases to hypothyroidism. Iodothyronine 5'-deiodinating activity was found in rat lung and eye, and the reaction was all or nearly all type I in both. Activity in the eye was virtually absent from the lens and vitreous humor. In immature rat cerebrum, pituitary, lung, and eye, between gestational day 17 and postnatal day 21, there was a uniform pattern of an increase in type I 5'-deiodination activity over time, until adult levels were attained. The ages at which adult activity levels were reached varied from tissue to tissue, however. Type II activity was present at the earliest ages tested in the cerebrum (gestational day 17), pituitary, and brown adipose tissue (day of birth). In cerebral cortex, type II activity was highest at day 21 postnatally and equal at birth and in adulthood, and in pituitary and brown adipose tissue it was higher in adulthood than at birth. T3 tyrosyl ring deiodinating activity was several times greater in homogenates of eye and placenta than in cerebral homogenates. In all three tissues, there was similar, dose-dependent inhibition of [125I]T3 tyrosyl deiodination by 5 nM and 20 nM nonradioactive T3. In the eye and brain, T3 tyrosyl deiodination rates decreased progressively with age from gestational day 17 to postnatal day 7.(ABSTRACT TRUNCATED AT 400 WORDS)

Interaction of herpes simplex virus-induced DNA polymerase with 9-(1,3-dihydroxy-2-propoxymethyl)guanine triphosphate.

The triphosphate of 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG) competitively inhibits incorporation of dGTP into DNA catalyzed by DNA polymerases specified by both type 1 and type 2 herpes simplex virus. K1 values were estimated to be 33 nM for type 1 and 46 nM for type 2-specified DNA polymerase. DHPG acted as an alternate substrate to dGTP for the virus-specified DNA polymerase. Incorporation of DHPG into DNA resulted in the slowing down of the rate of DNA synthesis. The position of DHPG incorporation was analyzed, and it was found to enter both internal and terminal linkages. DNA which contained DHPG at termini was found to competitively inhibit utilization of activated DNA as primer. DNA polymerase alpha and DNA polymerases from several phosphonoformic acid-resistant herpes simplex virus type 1 strains were examined for sensitivity to 9-(1,3-dihydroxy-2-propoxymethyl)guanine triphosphate. A lack of correlation between the in vivo sensitivities of the virus mutants and the K1 values of the DNA polymerases was noted.