ELECTRON-BEAM PATTERNING OF TEFLON AF FOR SURFACE PLASMON RESONANCE SENSING

Variable pressure electron beam etching and lithography for Teflon AF has been demonstrated. The relation between dose and etching depth is tested under high vacuum and water vapor. High resolution structures as small as 75 nm half-pitch have been resolved. Several simulation tools were tested for surface plasmon excitation. Grating based dual mode surface plasmon excitation has been shown numerically and experimentally

A Hybrid Achromatic Metalens

Metamaterials and metasurfaces are widely used to manipulate electromagnetic waves over a broad range of wavelengths. Several recent efforts have focused on metalenses, ultra-thin optical elements that focus light using subwavelength structures. Compared to their refractive counterparts, metalenses offer reduced size and weight, improved manufacturability, and new functionality such as polarization control. However, metalenses that correct chromatic aberration also suffer from markedly reduced focusing efficiency. Here we introduce a Hybrid Achromatic Metalens (HAML), that overcomes this trade-off and offers improved focusing efficiency over a broad wavelength range from 1000 - 1800 nm. Fabricated HAMLs demonstrated diffraction limited performance for numerical apertures (NA) of 0.27, 0.11, and 0.06 with average focusing efficiencies $> 60\%$ and maximum efficiencies ~ $80\%$. HAMLs can be designed by combining recursive ray-tracing and simulated phase libraries rather than computational intensive global search algorithms. Moreover, HAMLs can be fabricated in low-refractive index materials using multi-photon lithography for customization or using molding for mass production.Comment: 20 pages, 7 figure

A Hybrid Achromatic Metalens

Metalenses, ultra-thin optical elements that focus light using subwavelength structures, have been the subject of a number of recent investigations. Compared to their refractive counterparts, metalenses offer reduced size and weight, and new functionality such as polarization control. However, metalenses that correct chromatic aberration also suffer from markedly reduced focusing efficiency. Here we introduce a Hybrid Achromatic Metalens (HAML) that overcomes this trade-off and offers improved focusing efficiency over a broad wavelength range from 1000-1800 nm. HAMLs can be designed by combining recursive ray-tracing and simulated phase libraries rather than computationally intensive global search algorithms. Moreover, HAMLs can be fabricated in low-refractive index materials using multi-photon lithography for customization or using molding for mass production. HAMLs demonstrated diffraction limited performance for numerical apertures of 0.27, 0.11, and 0.06, with average focusing efficiencies greater than 60% and maximum efficiencies up to 80%. A more complex design, the air-spaced HAML, introduces a gap between elements to enable even larger diameters and numerical apertures

Experimental and theoretical investigation of waveguided plasmonic surface lattice resonances

Plasmonic nanostructures are good candidates for refractive index sensing applications through the surface plasmon resonance due to their strong dependence on the surrounding dielectric media. However, typically low quality-factor limits their application in sensing devices. To improve the quality-factor, we have experimentally and theoretically investigated two-dimensional gold nanoparticle gratings situated on top of a waveguide. The coupling between the localized surface plasmon and waveguide modes results in Fano-type resonances, with high quality-factors, very similar to plasmonic surface lattice resonances. By combining plasmonic surface lattice resonance and waveguide theory, we present a theoretical framework describing the structures. By immersing the fabricated samples in three different media we find a sensitivity of ∼50 nm/RIU and figure of merit of 8.9, and demonstrate good agreement with the theory presented. Further analysis show that the sensitivity is very dependent on the waveguide parameters, grating constant and the dielectric environment, and by tuning these parameters we obtain a theoretical sensitivity of 887 nm/RIU.publishedVersio

Disposition Kinetics and Optimal Dosage of Ciprofloxacin in Healthy Domestic Ruminant Species

The purpose of this experimental study was to determine the disposition kinetics and optimal dosages of ciprofloxacin in healthy domestic ruminant species including adult female buffalo, cow, sheep and goat. The drug was given as a single intramuscular dose of 5 mg/kg. The plasma concentrations of the drug were determined with HPLC and pharmacokinetic variables were determined. The biological half-life (t1/2 β was longer in cows (3.25 ± 0.46 h) followed by intermediate values in buffaloes (3.05 ± 0.20 h) and sheep (2.93 ± 0.45 h) and shorter in goats (2.62 ± 0.39 h). The volume of distribution (Vd) in buffaloes was 1.09 ± 0.06 l/kg, cows 1.24 ± 0.16 l/kg, sheep 2.89 ± 0.30 l/kg and goats 3.76 ± 0.92 l/kg. Total body clearance (ClB) expressed in l/h/kg was minimum in buffaloes 0.25 ± 0.02 followed by values in cows 0.31 ± 0.02 and sheep 0.75 ± 0.04 and maximum in goats 1.09 ± 0.11. An optimal dosage regimen for 12-h interval consisted of 5.17, 5.62, 6.54 and 6.10 mg/kg body weight as priming and 4.84, 5.37, 6.26 and 5.91 mg/kg body weight as maintenance intramuscular dose in buffalo, cow, sheep and goat, respectively. The manufacturers of ciprofloxacin have claimed 5 mg/kg dose to be repeated after 24 h. However, the investigated dosage regimen may be repeated after 12 h to maintain MIC at the end of the dosage interval. Therefore, it is imperative that an optimal dosage regimen be based on the disposition kinetics data determined in the species and environment in which a drug is to be employed clinically

An ultrabroadband 3D achromatic metalens

We design and fabricate ultra-broadband achromatic metalenses operating from the visible into the short-wave infrared, 450-1700 nm, with diffraction-limited performance. A hybrid 3D architecture, which combines nanoholes with a phase plate, allows realization in low refractive index materials. As a result, two-photon lithography can be used for prototyping while molding can be used for mass production. Experimentally, a 0.27 numerical aperture (NA) metalens exhibits 60% average focusing efficiency and 6% maximum focal length error over the entire bandwidth. In addition, a 200 μm diameter, 0.04 NA metalens was used to demonstrate achromatic imaging over the same broad spectral range. These results show that 3D metalens architectures yield excellent performance even using low-refractive index materials, and that two-photon lithography can produce metalenses operating at visible wavelengths.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

An ultrabroadband 3D achromatic metalens

We design and fabricate ultra-broadband achromatic metalenses operating from the visible into the short-wave infrared, 450–1700 nm, with diffraction-limited performance. A hybrid 3D architecture, which combines nanoholes with a phase plate, allows realization in low refractive index materials. As a result, two-photon lithography can be used for prototyping while molding can be used for mass production. Experimentally, a 0.27 numerical aperture (NA) metalens exhibits 60% average focusing efficiency and 6% maximum focal length error over the entire bandwidth. In addition, a 200 μm diameter, 0.04 NA metalens was used to demonstrate achromatic imaging over the same broad spectral range. These results show that 3D metalens architectures yield excellent performance even using low-refractive index materials, and that two-photon lithography can produce metalenses operating at visible wavelengths

Development and Validation of a RP-HPLC Method for Simultaneous Determination of Levofloxacin and Moxifloxacin in Pharmaceutical Dosage Forms

A simple, fast and economic reversed phase high performance liquid chromatographic (HPLC) method has been successfully developed and validated for simultaneous determination of fluoroquinolone analogs namely levofloxacin and moxifloxacin in both pure form (as API) and in pharmaceutical dosage forms. The method was validated according to the guidelines of ICH, FDA and USP with respect to accuracy, precision and linearity. For method development a C-18 bonded silica column (250 x 4.6 mm, 5μ, Phenomenex, Inc) was used with a mobile phase comprising of 10% aqueous solution of acetic acid and acetonitrile in a ratio of 80:20 v/v. The flow rate was 0.5 mL/min and effluents were monitored at 300 nm and the retention times were found to be at 7.0±0.1 min and 10.59±0.1 min for levofloxacin and moxifloxacin, respectively. The recovery was found to be more than 99% for each spiked samples of levofloxacin and moxifloxacin, demonstrating the accuracy of the protocol. Intra-day and inter-day precisions of the new method were less than the maximum allowable limit (RSD% £ 2.0) according to FDA. The method showed linear response with correlation coefficient value of 0.9975 in both the cases. Therefore, the developed method was found to be simpler, accurate, reproducible, efficient and less time consuming and can be successfully applied for the simultaneous assay of levofloxacin and moxifloxacin formulations.HPLC, method development, validation, levofloxacin, moxifloxacin

Development and Validation of a RP-HPLC Method for Simultaneous Determination of Levofloxacin and Moxifloxacin in Pharmaceutical Dosage Forms

A simple, fast and economic reversed phase high performance liquid chromatographic (HPLC) method has been successfully developed and validated for simultaneous determination of fluoroquinolone analogs namely levofloxacin and moxifloxacin in both pure form (as API) and in pharmaceutical dosage forms. The method was validated according to the guidelines of ICH, FDA and USP with respect to accuracy, precision and linearity. For method development a C-18 bonded silica column (250 x 4.6 mm, 5μ, Phenomenex, Inc) was used with a mobile phase comprising of 10% aqueous solution of acetic acid and acetonitrile in a ratio of 80:20 v/v. The flow rate was 0.5 mL/min and effluents were monitored at 300 nm and the retention times were found to be at 7.0±0.1 min and 10.59±0.1 min for levofloxacin and moxifloxacin, respectively. The recovery was found to be more than 99% for each spiked samples of levofloxacin and moxifloxacin, demonstrating the accuracy of the protocol. Intra-day and inter-day precisions of the new method were less than the maximum allowable limit (RSD% £ 2.0) according to FDA. The method showed linear response with correlation coefficient value of 0.9975 in both the cases. Therefore, the developed method was found to be simpler, accurate, reproducible, efficient and less time consuming and can be successfully applied for the simultaneous assay of levofloxacin and moxifloxacin formulations.HPLC, method development, validation, levofloxacin, moxifloxacin

“Losing the Brakes”—Suppressed Inhibitors Triggering Uncontrolled <i>Wnt</i>/<i>ß-Catenin</i> Signaling May Provide a Potential Therapeutic Target in Elderly Acute Myeloid Leukemia

Dysregulated Wnt/β-catenin signal transduction is implicated in initiation, propagation, and poor prognosis in AML. Epigenetic inactivation is central to Wnt/β-catenin hyperactivity, and Wnt/β-catenin inhibitors are being investigated as targeted therapy. Dysregulated Wnt/β-catenin signaling has also been linked to accelerated aging. Since AML is a disease of old age (>60 yrs), we hypothesized age-related differential activity of Wnt/β-catenin signaling in AML patients. We probed Wnt/β-catenin expression in a series of AML in the elderly (>60 yrs) and compared it to a cohort of pediatric AML (n = 101) were evaluated for key Wnt/β-catenin molecule expression utilizing the NanoString platform. Differential expression of significance was defined as >2.5-fold difference (p 60 yrs) were identified in this cohort. Normal bone marrows (n = 10) were employed as controls. Wnt/β-catenin target genes (MYC, MYB, and RUNX1) showed upregulation, while Wnt/β-catenin inhibitors (CXXR, DKK1-4, SFRP1-4, SOST, and WIFI) were suppressed in elderly AML compared to pediatric AML and controls. Our data denote that suppressed inhibitor expression (through mutation or hypermethylation) is an additional contributing factor in Wnt/β-catenin hyperactivity in elderly AML, thus supporting Wnt/β-catenin inhibitors as potential targeted therapy