Separated Spots Research Articles

Minimized speckle noise in lens-less holographic projection by pixel separation

Images displayed by holographic methods on phase-only light modulators inevitably suffer from speckle noise. It is partly caused by multiple uncontrolled interferences between laser light rays forming adjacent pixels of the image while having a random phase state. In this work the experimental proof of concept of an almost speckle-less projection method is presented, which assumes introducing a spatial separation of the image pixels, thus eliminating the spurious interferences. A single displayed sub-frame consists of separated light spots of very low intensity error. The sub-frames with different sampling offsets are then displayed sequentially to produce a non-fragmented color final image.

Dietary Phthalates and Low-Grade Albuminuria in US Children and Adolescents

Low-grade albuminuria is an indicator of endothelial dysfunction and is associated with an increased risk of cardiovascular disease. A graded level of exposure to bisphenol A was recently identified to be associated with increased risk of low-grade albuminuria in children and adults. Because bisphenol A and phthalates coexist as dietary contaminants, this study investigated whether exposure to phthalates is also associated with low-grade albuminuria. Data were examined from 667 children who participated in the 2009-2010 National Health and Nutrition Examination Survey and who had results for urinary phthalate metabolites and albumin excretion. Urinary albumin and creatinine concentrations were measured in a first morning specimen using a solid-phase fluorescent immunoassay and a Roche/Hitachi Modular P Chemistry Analyzer with an enzymatic method, respectively. Phthalate metabolites were analyzed in a separate spot urine sample from each participant, using high-performance liquid chromatography and tandem mass spectroscopy. For each (roughly) 3-fold increase in metabolites of di-2-ethylhexylphthalate (a high molecular weight phthalate commonly found in foods), a 0.55 mg/g increase in albumin/creatinine ratio (ACR) was identified (P=0.02), whereas a 1.30-fold odds of a higher ACR quartile was also identified for each (roughly) 3-fold increase (P=0.02). Higher ACR was not identified in relationship to metabolites of lower molecular phthalates commonly found in lotions or shampoos, suggesting specificity. Although reverse causation and unmeasured confounders represent alternative explanations, these findings, in conjunction with our earlier data on bisphenol A, indicate that a wide array of environmental toxins may adversely affect albuminuria and potentially increase the risk of cardiovascular disease. In view of the potential long-term health implications of ongoing exposure in this vulnerable subpopulation, our data support both further study and renewed regulatory efforts to limit exposure during childhood.

Light microscopy and scanning electron microscopy analysis of rigid curved interface femtosecond laser–assisted and manual anterior capsulotomy

To study the microanatomic edge structures of anterior lens capsule specimens derived from manual and femtosecond laser-assisted capsulotomies. Department of Ophthalmology, Goethe-University, Frankfurt, Germany. Experimental study. Of 60 eyes with lens removal and intraocular lens implantation, 30 received a manual capsulotomy and 30 received a femtosecond laser-assisted capsulotomy (Lensx, rigid curved interface, pulse energy 15 μJ, spot separation 4 μm, layer separation 3 μm). After anterior capsule removal, tissues were immediately fixed in 4.5% formalin. Approximately 30 minutes after fixation, the tissues were removed from the fixation containers and air dried for at least 2 hours. Fifteen capsules in each group had further staining for light microscopy (LM). The surface of the capsulotomy edge was the primary focus of LM and scanning electron microscopy (SEM). Cell configuration, capsule shape, and abnormalities were evaluated. Subjective LM and SEM analysis showed smooth edges at all magnifications, no cell destruction, and cells up to the cutting edge in the manual capsulotomy group. Light microscopy demonstrated almost continuous anterior capsule incisions of the femtosecond laser-assisted capsulotomy, a prominent demarcation line along the cutting edge, and several tags and bridges. Scanning electron microscopy showed microgrooves and valley- and mountain-like structures as signs of the photodisruption process. Compared with manual procedures, curved, rigid interface femtosecond laser-assisted capsulotomy specimens using 15 μJ pulse energy showed tags, bridges, rougher edges, and demarcation lines on the capsulotomy edges on SEM but subjectively estimated a more round shape on LM. Mr. Klaproth received travel reimbursements and/or lecture fees from Alcon Laboratories, Inc., Rayner Intraocular Lenses Ltd., and Oculus GmbH. Dr. Kohnen received travel reimbursements, grant support, and/or lecture fees from Alcon Laboratories, Inc., Abbott Medical Optics, Inc., Bausch & Lomb, Carl Zeiss Meditec AG, Neoptics AG, Rayner Intraocular Lenses Ltd., and Schwind eye-tech-solutions GmbH and Co. KG; he is a consultant to Alcon Laboratories, Inc., Carl Zeiss Meditec AG, Rayner Intraocular Lenses Ltd., and Schwind eye-tech-solutions GmbH and Co. KG. No other author has a financial or proprietary interest in any material or method mentioned.

High-Throughput and Low-Cost Fabrication of Polymer Microscanner for Lighting Applications

A high-throughput and low-cost fabrication process for an optical microscanner is proposed for lighting applications. The process utilizes mold replication and transfer of printed functional layers to form a film. We confirmed that a high-throughput fabrication lasting less than 30 s could be obtained by using a mold with a knife edge. A polymer microscanner with feature size of 0.6×2 mm2 was successfully fabricated using our process. The scanner was actuated by magnetic forces generated by an external coil, and the mirror tilt angle was successfully measured by a strain gauge formed by the functional layer transfer. By synchronizing the LED input signal and the polymer scanner tilt angle, the illuminance distribution could be controlled. For example, this distribution could be expanded from 10 to 50° or divided into two separated spots. We believe that our developed process can address new MEMS applications such as commercial lighting.

Stromal bed quality and endothelial damage after femtosecond laser cuts into the deep corneal stroma

AimTo evaluate the stromal bed quality and endothelial damage after femtosecond laser (FSL) cuts into the deep corneal stroma.MethodsUsing a 150-kHz FSL, a lamellar cut was aimed at a depth...

Effect of 60 kHz and 150 kHz Femtosecond Lasers on Corneal Stromal Bed Surfaces: A Comparative Study

Purpose. To compare the effect of 60 kHz and 150 kHz femtosecond (FS) laser on the corneal stromal bed surfaces (SBS). Methods. Sixteen human donor corneal tissues unsuitable for transplantation were used. Anterior and posterior lamella was obtained using 60 kHz and 150 kHz FS laser. A standard depth of 400 μm was set for anterior lamellar keratoplasty (ALK) and endothelial lamellar keratoplasty (ELK). The quality and smoothness of the SBS post-FS laser dissection were graded for statistics. Results. No intraoperative complications were found. The side cuts were straight, and the SBS appeared smoother in cuts obtained using 150 kHz. The average values of the SBS quality of the anterior lamellar cut were found to be 2.25 (±0.28) for 60 kHz and 3.125 (±0.25) for 150 kHz (P = 0.0039). Whereas, 2 (±0.4) for 60 kHz and 2.75 (±0.28) for 150 kHz (P = 0.0273) was the quality observed in endothelial cuts. No significant difference was found between anterior and posterior cuts performed using the same FS laser (60 kHz or 150 kHz) (P > 0.05). Conclusions. The 60 kHz and 150 kHz FS lasers are equally effective in performing lamellar dissection for ALK and ELK. 150 kHz FS laser allows a tighter spot and layer separation which creates a slightly smoother SBS.

Unilateral Rainbow Glare After Uncomplicated Femto-LASIK Using the FS-200 Femtosecond Laser

To report a case of rainbow glare following femtosecond laser-assisted LASIK (femto-LASIK) with the Wavelight FS-200 femtosecond laser (Alcon Laboratories, Inc., Fort Worth, TX). A patient was treated bilaterally for myopia with femto-LASIK using the FS-200 femtosecond laser. Postoperatively, he complained of rainbow glare in his right eye. Three months postoperatively, the induced grating pattern (hyperreflective spot-like zones corresponding to the surgeon-programmed spot and line separation distance of the FS-200 femtosecond laser) was demonstrated with confocal microscopy at the level of the flap interface in the right eye. This is the first report of rainbow glare following femto-LASIK with the FS-200 femtosecond laser documented with in vivo confocal microscopy.

Daytime VLF emissions at the Sodankyla Observatory (L ∼ 5.3) at the front of high-speed solar wind streams

We discuss the results of an analysis of digital high-sensitivity ground-based observations of very low frequency (VLF) emissions, carried out in Northern Finland (L = 5.3) in May–June 2012. During this period of time, we found that three high-speed solar wind streams approached the Earth’s magnetosphere and at the front of these fluxes long-lasting intense daytime bursts of VLF emissions were generated in two frequency bands: above and below ∼2.5 kHz. At frequencies above ∼2.5–3.0 kHz, there were VLF hiss waves, the temporal structure of which consisted of a quasi-periodic sequence of separate stronger spots of noise signals. The low-frequency band was represented by chorus waves, superimposed on intense hiss emissions at frequencies below ∼1.5 kHz. The high-frequency (f > 2.5 kHz) waves were elliptic and, predominately, left-hand polarized and the low-frequency waves were right-hand polarized. It was supposed that high-frequency VLF hiss waves were generated at L 5. We discuss a possible scenario of the generation and propagation of the VLF emissions observed.

HPTLC validated stability indicating assay method for marketed herbal antihypertensive formulations

BackgroundReserpine is an indole alkaloid and found to be very unstable in various conditions previously. Here a simple, selective, precise and stability indicating high-performance thin-layer chromatographic method of analysis of reserpine was developed and validated. Materials and methodsThe method employed TLC plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consists of chloroform:acetone (7:3). This system was found to give well separated spots of reserpine at Rf (0.28 ± 0.02). The analysis of reserpine was carried out at 268 nm. ResultsThe linear regression analysis data for the calibration plots showed good linear relationship with r = 0.998 and 0.999 with respect to peak height and peak area, respectively, in the concentration range 200–1000 ng per spot. The method was validated for accuracy, precision, recovery and robustness. The limits of detection and quantification were 109.85 and 292.10 ng per spot, respectively. The conditions prescribed in the parent drug stability testing guidelines (Q1AR) issued by International Conference on Harmonization (ICH). ConclusionThe present study describes degradation of reserpine under different ICH prescribed stress conditions (acid and base hydrolysis, oxidation, dry and wet heat degradation and photo-degradation) and establishment of stability indicating HPTLC assay. The drug undergoes degradation under acidic and basic conditions, oxidation, dry and wet heat treatment and photo degraded. As the method could effectively separate the drug form its degradation products, it can be employed as a stability indicating one.

Stability-indicating densitometric determination of some angiotensin II receptor antagonists in presence of their degradation products

Summary A simple, selective, precise, and stability-indicating thin-layer chromatographic method has been developed and validated for analysis of some angiotensin II receptor antagonists (AIIRAs), namely, Losartan potassium (Los-K), Irbesartan (Irb), and Candesartan cilexetil (Cand) in the bulk drug and in pharmaceutical formulations (tablets). The method was based on using TLC plates pre-coated with silica gel G 60 on aluminum sheets as stationary phase and the development system was performed using chloroform:methanol (9:1) giving well separated and compact spots for all the studied drugs (RF values 0.41–0.53). The separated spots were characterized by viewing under the UV lamp, then visualized as orange spots by spraying with Dragendorff's reagent and measured by densitometry. Under the optimum chromatographic conditions, linear relationships were obtained between response and concentrations of each studied drug with high correlation coefficients (0.9985–0.9994). Good accuracy and precision were successfully obtained for the analysis of tablets containing each drug alone or combined with diuretic drug hydrochlorothiazide (HCTZ). No interferences could be observed from the co-formulated HCTZ, commonly encountered excipients present in tablets as well as the degradation products. The results were compared successfully with reported methods and can be used as a stability-indicating assay.

Development of validated stability-indicating simultaneous estimation of Tenofovir disoproxil fumarate and emtricitabine in tablets by HPTLC

AimA simple, accurate, precise and rapid HPTLC methods for simultaneous determination of Tenofovir disoproxil fumarate (TDF) and emtricitabine (ETB) in combined dosage forms. MethodThe method is based on HPTLC separation of the two drugs followed by densitometric measurements of their spots at 276 nm. The separation was carried out on Merck TLC aluminium sheets of silica gel 60F 254 using toluene: ethyl acetate: methanol: acetic acid (6: 4: 3:0.4, v/v/v) as a mobile phase. Stability of TDF and ETB was carried out by forced degradation study. ResultTDF and ETB gave sharp and well defined peak at Rf 0.41 and 0.68, respectively. Calibration curves were linear in range 150–1500 ng/spot and 100–1000 ng/spot for TDF and ETB, respectively. Method was successively applied to tablet formulation. Stability study shows that the chromatograms of samples degraded with acid, base, hydrogen peroxide and light showed well separated spots of pure TDF and ETB as well as some additional peaks at different Rf values. ConclusionThe method is successively applied to pharmaceutical formulation; No chromatographic interferences from the tablet excipients were found. The suitability of this HPTLC method for quantitative determination of the compounds is proved by validation in accordance with the requirements of ICH guidelines.

Rapid detection of haloarchaeal carotenoids via liquid–liquid microextraction enabled direct TLC MALDI-MS

For the first time, we demonstrate the use of TiO2 nanoparticles (NPs) for enhancing the carotenoid production by the extremophilic haloarchea, Haloferax mediterranei. TiO2 NPs at optimal concentration of 375mg/L results in a 95% increase in the production of carotenoid pigment compared to the control (no TiO2 NPs). The carotenoid pigments extracted from TiO2 NPs treated H. mediterranei cells, were separated using thin layer chromatography (TLC). The separated carotenoid spots were subjected directly for MALDI MS detection. To limit the sample diffusion during matrix addition on TLC plates, a simple bordering mode was exercised. Using this method we were able to detect the pigments successfully using MALDI-MS, directly from TLC plates after separation. In addition, we also applied the Pt NPs capped with ODT via Liquid–liquid microextraction (LLME) for extracting the pigment molecules from the halobacteria in MALDI-MS. These novel NP approaches possess numerous advantages such as; rapidity, ease in synthesis, high sensitivity and low cost.

On‐Chip Protein Biosynthesis

Spot on! Cell-free protein expression on surfaces can be implemented in biosensors and in microfluidic devices like that shown in the picture. Proteins are generated and immobilized successively on separated spots in a microfluidic reactor. This approach opens up novel opportunities for basic and applied biomedical research.

Comparison of first dimension IPG and NEPHGE techniques in two-dimensional gel electrophoresis experiment with cytosolic unfolded protein response in Saccharomyces cerevisiae

BackgroundTwo-dimensional gel electrophoresis (2DE) is one of the most popular methods in proteomics. Currently, most 2DE experiments are performed using immobilized pH gradient (IPG) in the first dimension; however, some laboratories still use carrier ampholytes-based isoelectric focusing technique. The aim of this study was to directly compare IPG-based and non-equilibrium pH gradient electrophoresis (NEPHGE)-based 2DE techniques by using the same samples and identical second dimension procedures. We have used commercially available Invitrogen ZOOM IPGRunner and WITAvision systems for IPG and NEPHGE, respectively. The effectiveness of IPG-based and NEPHGE-based 2DE methods was compared by analysing differential protein expression during cytosolic unfolded protein response (UPR-Cyto) in Saccharomyces cerevisiae.ResultsProtein loss during 2DE procedure was higher in IPG-based method, especially for basic (pI > 7) proteins. Overall reproducibility of spots was slightly better in NEPHGE-based method; however, there was a marked difference when evaluating basic and acidic protein spots. Using Coomassie staining, about half of detected basic protein spots were not reproducible by IPG-based 2DE, whereas NEPHGE-based method showed excellent reproducibility in the basic gel zone. The reproducibility of acidic proteins was similar in both methods. Absolute and relative volume variability of separate protein spots was comparable in both 2DE techniques. Regarding proteomic analysis of UPR-Cyto, the results exemplified parameters of general comparison of the methods. New highly basic protein Sis1p, overexpressed during UPR-Cyto stress, was identified by NEPHGE-based 2DE method, whereas IPG-based method showed unreliable results in the basic pI range and did not provide any new information on basic UPR-Cyto proteins. In the acidic range, the main UPR-Cyto proteins were detected and quantified by both methods. The drawback of NEPHGE-based 2DE method is its failure to detect some highly acidic proteins. The advantage of NEPHGE is higher protein capacity with good reproducibility and quality of spots at high protein load.ConclusionsComparison of broad range (pH 3–10) gradient-based 2DE methods suggests that NEPHGE-based method is preferable over IPG (Invitrogen) 2DE method for the analysis of basic proteins. Nevertheless, the narrow range (pH 4–7) IPG technique is a method of choice for the analysis of acidic proteins.

T-Cyg1-12664: a low-mass chromospherically active eclipsing binary in the Kepler field

The eclipsing binary T-Cyg1-12664 was observed both spectroscopically and photometrically. Radial velocities of both components and ground-based VRI light curves were obtained. The Kepler's R-data and radial velocities for the system were analysed simultaneously. Masses and radii were obtained as 0.680$\pm$0.021 M$_{\odot}$ and 0.613$\pm$0.007 R$_{\odot}$for the primary and 0.341$\pm$0.012M$_{\odot}$ and 0.897$\pm$0.012R$_{\odot}$ for the secondary star. The distance to the system was estimated as 127$\pm$14 pc. The observed wave-like distortion at out-of-eclipse is modeled with two separate spots on the more massive star, which is also confirmed by the Ca {\sc ii} K and H emission lines in its spectra. Locations of the components in the mass-radius and mass-effective temperature planes were compared with the well-determined eclipsing binaries' low-mass components as well as with the theoretical models. While the primary star's radius is consistent with the main-sequence stars, the radius of the less massive component appears to be 2.8 times larger than that of the main-sequence models. Comparison of the radii of low-mass stars with the models reveals that the observationally determined radii begin to deviate from the models with a mass of 0.27 \Msun and suddenly reaches to maximum deviation at a mass of 0.34 \Msun. Then, the deviations begin to decrease up to the solar mass. The maximum deviation seen at a mass of about 0.34 \Msun is very close to the mass of fully convective stars as suggested by theoretical studies. A third star in the direction of the eclipsing pair has been detected from our VRI images. The observed infrared excess of the binary is most probably arisen from this star which may be radiated mostly in the infrared bands.

Surface Quality of Femtosecond Dissected Posterior Human Corneal Stroma Investigated With Atomic Force Microscopy

To investigate and compare the surface roughness and morphology of posterior stromal lenticules created with a femtosecond laser using various pulse energies to that obtained with a mechanical microkeratome. A 150 kHz femtosecond laser platform (IntraLase iFS; Abbott Medical Optics) was programmed to create an 8.5-mm-diameter posterior stromal lenticule in 12 human corneal tissues. Specimens were dissected using different pulse energies (1.00, 0.75, 0.65, and 0.50) and fixed 2 μm spot separations. Three additional posterior corneal lenticules were prepared using a mechanical microkeratome (Moria Evolution 3; Moria). After the procedure, each corneal tissue was examined by atomic force microscopy (Autoprobe CP; Veeco). Femtosecond laser-treated tissues revealed similar morphological features, however, with significant differences in surface roughness in relation to the energy pulse used for lamellar dissection (P<0.001). The most regular stromal surface was achieved when using 0.50 μJ pulse energy; on the contrary, the roughest specimens were those dissected using 1.00 μJ pulse energy. No differences in surface roughness were measured between mechanically resected tissues and those treated using 0.50 μJ pulse energy (P>0.05). Atomic force microscopy submicron analysis of femtosecond-dissected donor tissues provided quantitative demonstration of the relation between pulse energy and stromal surface roughness. Surface quality of posterior corneal lenticules, comparable with that provided by mechanical microkeratome, is significantly improved when setting pulse energy for lamellar dissection of 0.50-μJ and 2-μm spot separations.

Research on the Segmentation Method of Rice Leaf Disease Image

In Order to Improve the Segmentation Effect of the Rice Leaf Disease Images, we Take Optimal Iterative Threshold Method,OTSU Method and Fuzzy C-means Clustering Algorithm to Make Adaptive Segmentation of Rice Disease Images which Were Collected under Different Circumstances. through Comparative Analysis, Experimental Results Show that: Three Methods All Can Effective Separate Spot from the Leaves; in Comparison, the Effect of the Fuzzy C-means Clustering Algorithm Is the Best, but the Number of Iterations Is too many and the Time Spent on it Is the Most; the Effect of OTSU Method Is Lesser, Optimal Iterative Threshold Method Is the Worst. Comprehensive Considering the Segmentation Accuracy and Efficiency, the Paper Chooses OTSU as the Segmentation Method of the Rice Leaf Disease Images.

Device and programs for investigation of biological objects autofluorescence

A method of fluorescent sub-diffractional microscopy is proposed based on using object dyeing by special dye, which is able to bind to some object structures and initially not absorb light, used for excitation of fluorescence. As a result of some processes small part of molecules is activated, that is converted to molecule able to absorb light and fluoresce sufficiently long to be registered by a sensitive video camera as separate spots covering tens of pixcels of camera matrix. Then registered molecules must be photobleached or transformed to nonfluorescing state by other influence and new portion of molecules is activated. This circle of "activation"--"fluorescence excitation and registration"--"photobleaching" may be repeated thousands times. The accuracy of center spots determination may be up to 2 nm. A collection of all calculated centers of spots in all registered frames may be used for reconstruction of object image with resolution not limited by diffraction. A method of improving visibility of spots produced by single molecules in object having autofluorescence is described.

Thin layer chromatographic investigation of some veterinary drugs

A simple technique, using solvent extraction and thin layer chromatography for the detection and separation of a number of commonly prescribed veterinary drugs was studied. Blood and urine have been considered as possible biological samples taken from the animals. The extraction of each sample was done according to the type of the drug as it is acidic or basic, then the extract was spotted on TLC plate by capillary tube after lining the starting line first. Separations of the components of the samples were developed after running the plate in a tight lid tank containing solvent (mobile phase). The identification of separated spots were carried out after lining the end line for the solvent front then by spraying the plate with mercurous nitrate reagent for acidic drugs and acidic iodoplatinate or potassium permanganate reagent for basic drugs. The rate of flow value (R f) for each compound was measured and the color of spots were determined. This work provides a simple and rapid qualitative technique for the detection of veterinary drugs used at therapeutic doses and in overdosage.

Scanned-spot-array extreme ultraviolet imaging for high-volume maskless lithography

High-volume maskless lithography systems typically operate by raster-scanning a large array of focused radiation spots across an exposure surface while the spot intensities are modulated. This paper outlines a design concept and optical simulation results for a spot-scanning extreme ultraviolet (EUV) system using a 10×-reduction, flat-image Schwarzschild projection system consisting of only two mirrors. The spots are generated in the system's object space by means of blazed, multilevel zone-plate microlenses configured as Schupmann achromatic doublets, which are highly efficient and are designed to nullify geometric aberration in the projection system. Coherent proximity effects are eliminated by partitioning the exposure radiation into discrete, diffraction-limited image spots, which have convergence cones of numerical aperture 0.3 at the 13.5-nm operating wavelength. The image spot separation is 2.5 μm, and the spot array covers a 10-mm square image field, sufficient to achieve printing throughput of order 30 (300-mm) wafers per hour. For simplicity, the spot intensities are all controlled by a single source modulator, allowing printing of 2.5 -μm periodic patterns without a spatial light modulator. The microlens manufacturing technology would be similar to that used for EUV mirrors and phase-shift masks, but with dramatically less stringent tolerance requirements.