Front Window Research Articles

Combined optical–electrical finite-element simulations of thin-film solar cells with homogeneous and nonhomogeneous intrinsic layers

A two-dimensional finite-element model was developed to simulate the optoelec- tronic performance of thin-film, p-i-n junction solar cells. One or three p-i-n junctions filled the region between the front window and back reflector; semiconductor layers were made from mixtures of two different alloys of hydrogenated amorphous silicon; empirical relation- ships between the complex-valued relative optical permittivity and the bandgap were used; a transparent-conducting-oxide layer was attached to the front surface of the solar cell; and a metallic reflector, either flat or periodically corrugated, was attached to the back surface. First, frequency-domain Maxwell postulates were solved to determine the spatial absorption of photons and thus the generation of electron-hole pairs. The AM1.5G solar spec- trum was taken to represent the incident solar flux. Second, drift-diffusion equations were solved for the steady-state electron and hole densities. Numerical results indicate that increasing the number of p-i-n junctions from one to three may increase the solar-cell efficiency by up to 14%. In the case of single p-i-n junction solar cells, our simulations indicate that efficiency may be increased by up to 17% by incorporating a periodically corrugated back reflector (as opposed to a flat back reflector) and by tailoring the bandgap profile in the i layer. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original pub- lication, including its DOI. (DOI: 10.1117/1.JPE.6.025502)

Invivo Pattern Recognition and Digital Image Analysis Shear Stress Distribution in Human Eye

Human eye is made of a number of structural components to deliver vision, and cornea is the front window of the eye. Human cornea is made of soft biological materials. It is unfriendly for exposures to the common energy levels of X-ray scans for repeated probing of its structural architecture. Here we study an alternative imaging methodology by using a normal white-light source. By exploiting the natural birefringent property of cornea, the shear stress distribution pattern and its directional characteristics on the surface of cornea is recognized in vivo. Digital image processing of corneal retardation helps us to locate the stress concentration zones on its surface and to study their features along preferential directions. Such digital image outputs could be used in future to bench mark the health standard of cornea as well as a potential identity signature of people’s eyes.

THE SYSTEM

1 0 5 R T H E S Y S T E M J E A N M c G A R R Y They were not married, but they were part of a system. In it, a certain freedom; outside, nothing. One was built low to the ground, chopped-o√ black hair, glasses, round face; the other, tall and seedy, a tea drinker and lover of ancient texts. Fatty lived in the present, patrolled the school with a raggedy hemline and clunky shoes. She was brilliant, and a fine singer, with an easy reach to high C. Betty and Boris, we called them, thrilled to see their command, in old days when two women were too many for one house and one bed. Not enough of something, and too much of something else. They had their routines, and never shared an o≈ce or a lunch where people could see. The nuns didn’t seem to mind. How could they, living the way they did, in twos and threes with wedding rings and Jesus as their bridegroom? They looked the other way; the spiciness came from us, although they tried to thin it out with vinegar and water, a panful of Ivory flakes, and rafts of Modess ‘‘. . . because.’’ Because why? Just because. And we were satisfied. The system made us strong. There wasn’t much room for speculation. There was fact: a joint 1 0 6 M c G A R R Y Y car and a house far enough away from campus, and from snoopy neighbors, to elude detection. For holidays with a religious note, each went home alone to a houseful of Catholic brothers and sisters, aunts and uncles, grandmas and kids. Boris was born with a face of crumbly plaster and a wall eye. Even as a baby, never smiled, and grew her body into a barrel, whose hoops would last as long as she did. The ‘‘hand grenade,’’ boys her age had called her, but they liked her. Everyone liked her, or was it fear? She had a mind of her own and an appetite – not just for food, which, in those days, was plentiful, coarse, and styled to fatten the best of the herd. She was secretive and lived inside her head, stocked with whatever she could find to read. She also liked gaping into front windows , eavesdropping in rude cafés and diners, hiding in the card section of the drugstore to hear what people were demanding, with or without a doctor’s order. Boris knew everything there was to know about the neighborhood, the parish, and the precinct by sixth grade, which she skipped. And suddenly, in junior high, having no boys to pal around with, her view darkened, and she spent more time on her knees in front of Our Lady of Fatima. That was the name of her church. In some ways, she was a boy, forced to be a girl, with a widowed mother and older brother studying to be a priest – and more than a priest, because already in Rome. So it was just mother and Boris at home. Her given name was Mary. Betty was born into a family of eleven boys. She was the baby, and lugging her home in a taxi, her mother took a spill on the ice, cracked her skull, broke her arm, and baby blue, for she was a blue baby, the first to survive, caught a cold and lived her first year in the hospital, an asylum, really, for the blind, the deaf, the retarded, the crippled, the defective at birth, the injured, and the sick. As soon as Betty could put two and two together – early, because she was a genius – she was a baby to watch. The nuns wanted to keep her for their own, for many of the surviving inmates joined their order the first day they could do it, at age fourteen, by the bishop’s special dispensation, because sta√ was needed and vocations to that servile order rare, and because their mother house was in the far reaches of Canada, and no one had heard of them. But Betty’s mother, never too hale and...

Leaving home without locking the front door and windows among young- single-women living alone in apartment buildings

Leaving home without locking the front door and windows among young- single-women living alone in apartment buildings

Concise Review: An Update on the Culture of Human Corneal Endothelial Cells for Transplantation

The cornea forms the front window of the eye, enabling the transmission of light to the retina through a crystalline lens. Many disorders of the cornea lead to partial or total blindness, and therefore corneal transplantation becomes mandatory. Recently, selective corneal layer (as opposed to full thickness) transplantation has become popular because this leads to earlier rehabilitation and visual outcomes. Corneal endothelial disorders are a common cause of corneal disease and transplantation. Corneal endothelial transplantation is successful but limited worldwide because of lower donor corneal supply. Alternatives to corneal tissue for endothelial transplantation therefore require immediate attention. The field of human corneal endothelial culture for transplantation is rapidly emerging as a possible viable option. This manuscript provides an update regarding these developments. Significance: The cornea is the front clear window of the eye. It needs to be kept transparent for normal vision. It is formed of various layers of which the posterior layer (the endothelium) is responsible for the transparency of the cornea because it allows the transport of ions and solutes to and from the other layers of the cornea. Corneal blindness that results from the corneal endothelial dysfunction can be treated using healthy donor tissues. There is a huge demand for human donor corneas but limited supply, and therefore there is a need to identify alternatives that would reduce this demand. Research is underway to understand the isolation techniques for corneal endothelial cells, culturing these cells in the laboratory, and finding possible options to transplant these cells in the patients. This review article is an update on the recent developments in this field.

Enhanced light trapping with double-groove grating in thin-film amorphous silicon solar cells

A design to enhance light absorption in thin-film amorphous silicon (a-Si) solar cells is proposed. It is achieved by patterning a double-groove grating with waveguide layer as the absorbing layer and coating a double-groove grating anti-reflective layer in the front window of the cell. The broadband absorption under normal incidence can be achieved for both TE and TM polarizations. It is shown that the averaged integrated absorptions have very large angle independence for the optimized solar cell. An qualitative understanding of such broadband enhanced absorption effect, which is attributed to the guided mode resonance, is presented. The conclusions can be exploited to guide the design of solar cells based on a grating structure.

Causes and Deaths of Peacocks in the Southern Expressway from Pinnanduwa to Godagama

Peacock (Pavo cristatus) is one of the largest and attractive birds in Sri Lanka. Indian peacocks are native to South Asia as well as to Sri Lanka. Low land dry grass areas are their range in Sri Lanka. During the construction of the southern expressway (SE), peacocks highly concentrated along the sides of the road between Pinnanduwa and Godagama. The objective of this study was to find causes, deaths and the methods to conserve peacocks. This research was based on the qualitative methods. Discussions were made with five expressway officers, four bus drivers, four usual passengers and three local individuals. The direct observation is also included as a data source for the study. During the construction of the SE from Pinnanduwa to Godagama, quite a number of peacocks newly inhabited on either side of the road and used to walk along and cross the road very often. Unfortunately, peacocks were victimised after the open of the SE to the public from 15th of March 2014. This is because the peacocks are fresh to the vehicles, they usually fly downwards, peacocks cannot run fast but vehicles maintain speed around 100 km per hour, they cannot react quickly because they are large and also the road is higher than the land surface. According to the field study, the accident usually happens during the morning hours between 6.00 am to 7.00 am and in the evening around 5.00 pm. There are eight buses with damaged front windows because of the colliding with the peacocks. During the first two weeks, the death of peacocks were two to three per day and dramatically down to five to seven per week after two months and the death is continuing from two to five per month at present. However, fencing either sides of the SE up to four to five meters high in the particular area and occasional under road corridors may help to conserve peacocks rather than putting up warning boards for the drivers. Keywords: Peacocks, Southern expressway

Spatial Atmospheric ALD of Functional Layers for CIGS Solar Cells

Spatial Atmospheric Atomic Layer Deposition combines the advantages of temporal ALD, i.e. excellent control of film composition and uniformity over large area substrates, with high growth rates (up to nm/s). In this paper we present a short overview of our research activity carried out on S-ALD of functional thin films for the front window of copper indium gallium di-selenide (CIGS) solar cells. Zn(O,S) and ZnO:Al are grown by co-injecting the vaporized precursors of the cationic (O, S) and anionic (Zn, Al) elements, respectively. An insight on the growth characteristics and properties of Zn(O,S) and ZnO:Al is presented.

The rear end collision and the wheel flying off protection using the reinforcement learning with the adaptive sound caution

Safety driving is to watch both the front and the side from the driver seat. In order to avoid a rear end collision for the other car and a wheel flying off its axle for the said car itself at the same time, Q-learning of reinforcement learning was used in this study. In this study, the image of the front whole window is always captured by camera. Here, a steering angle divided by eight categories toward the front is the action at of a wheel flying off protection and car speed divided by ten categories is that of the rear end collision protection. The status st is distance from the sideview mirror to the side ditch for the wheel flying and the length between the roof of the car which is running ahead and its rear bumper. In the training phase, so as to maximize the sum of the rewards taken from the environment as the vehicle's front window, the system updates the recursion Quantity of a state action combination Q(st,at) = Q(st,at) + α (rt + 1 + γ max[a]Q(st + 1,a) − Q(st,at)) (t:time, α:learning rate, γ: discount) periodically until its Q(st, at) value is converged individually. When rewards both for the rear end collision and wheel flying off become mature, the automatic operating routines are regarded to be completed. And when making use of this system, the code still watches the car distance from the ditch and the relative level of the front car and the adaptive caution sound which has three spectrum peaks along 0.5 through 6 kHz are rung, adjusting frequency, loudness, and duty corresponding to the severity if the car approaches the crisis.

Quantitative I n Operando Spectroscopic Measurements of Species Concentrations in a Sodium-Halide Cell

Introduction In order to meet the increasing demand for energy storage, new battery technologies are needed to fulfill the needs of a world where electricity is of increasing importance (1, 2). One of the difficulties of developing new battery technologies is characterizing the electrochemical reactions that occur within the battery electrolyte. In this work, the authors present a novel approach for quantitative in-operando optical measurements of electrochemistry in battery electrolytes. An optically accessible cell was fabricated using a ceramic ion exchange membrane made from NASICON (Na Ion Super Conductor), a promising alternative to β-alumina for molten sodium batteries for stationary storage applications (3, 4, 5)­­. Optical access was achieved by sandwiching the battery between two UV-transparent windows (Figure 1). The battery chemistry utilized a copper cathode contained in an aqueous sodium iodide catholyte solution. During charging, copper is stripped from the cathode to form aqueous CuI2 -. The full cell reaction is Na+ + 2I- +Cu(s) ↔ Na + CuI2 - The aim of this work was to monitor the species present in the catholyte solution spectroscopically. Species concentrations were determined from UV absorption spectra using absorption cross-sections measured through fundamental experiments and calculated through ab initio simulations. Experimental Figure 1: Conceptual drawing of the optically accessible sodium halide cell. Optical access allows for in-operando measurements of electrochemical species concentrations via spectroscopic methods. The channels for the anode and cathode are each 2 mm wide. The cathode is spaced 1 mm from the NASICON separator. The separator is 1 mm thick. A molten sodium battery was constructed inside the optical cell by machining a NASICON wafer to accommodate a molten sodium anode and an aqueous catholyte. The front window of the cell was machined to allow electrodes and plumbing to be passed into the cell. Viton gaskets were used to seal around the NASICON, separating the aqueous solution from the sodium. UV absorption spectroscopy was used to measure changes in CuI2 -concentration as the cell was operated. Fundamental spectroscopic experiments were carried out to isolate the spectra of relevant electrochemical species. Measurements of the absorption cross-sections of the electrochemical species were then used to make quantitative measurements of species concentration in operando. Ab initio calculations of the UV-visible absorption spectra of relevant electrochemical species and possible products of side reactions (Na+, I-, I3 -, I2, and CuI2 -) were performed at the TD-B3LYP//aug-ccpv5z-pp, TD-M062X//aug-ccpv5z-pp, and EOM-CCSD//aug-ccpv5z-pp levels of theory. Calculations were carried out in Gaussian 09. Results of the calculations were compared to experimental results to verify assignment of absorption features to species present in the electrolyte. Conclusions A fully functional, optically accessible cell based on molten sodium-halide chemistry with a NASICON ion exchange membrane has been demonstrated. Furthermore, quantitative measurements of relevant electrochemical species concentrations have been demonstrated. UV absorption cross-sections of the electrochemical species and possible side reaction products have also been measured experimentally and calculated through ab initio methods. Acknowledgements The authors would like to thank Dr. Imre Gyuk at the Department of Energy Office of Electricity for providing the funding for this work. The authors also thank Dr. David Ingersoll from Sandia National Laboratories for overseeing the project, Dr. Sai Bhavaraju and Matt Robins from Ceramatec for their battery expertise and advice, Dr. Huayang Zhu and Dr. Robert Kee at CSM for support in computational battery modeling, and Dr. C. Mark Maupin for supporting the ab initio calculations. References Farhangi, H. The path of the smart grid – IEEE Power and Energy Magazine. 2010 , 8 (1), 18-28.Yang, Z.; Zhang, J.; Kinter-Meyer, M.C.; Lu, X.; Choi, D.; Lemmon, J.P.; and Liu, J. Electrochemical energy storage for green grid. Chemical Reviews. 2011, 111(5), 3577-3613.Hueso, K.B.; Armand, M.; and Rojo, T. High temperature sodium batteries: status, challenges and future trends. Energy Environmental Sci. 2013, 6(3), 734-749.Bhavarju, S.; Robins, M.; and Boxley, C. Battery charge transfer mechanisms. US20140030571 A1, January 30, 2014Zhu, H.; Bhavarju, S.; and Kee, R.J. Computational model of a sodium–copper–iodide rechargeable battery. Electrochimica Acta. 2013 112, 629-639. Figure 1

DLC 박막을 통한 전자광학추적장비 신뢰성 개선

The Diamond Like Carbon(DLC) films for the Electro Optical Tracking System(EOTS) by using Plasma Enhanced Chemical Vapor Deposition(PECVD) method is presented. We achieve that the DLC films can reduce the surface delamination of thermal observation sensor front window due to the high hardness, low friction and chemical inertness which is comparable to a Si film. According to our experiment results, DLC films can be used for various electro optical systems to eliminate surface delamination.

Forma urbana tradicional e modernista

The objective of this paper is to discuss some of the implications of traditional urban form and modernist urban form, for the use and aesthetics of urban spaces, such as the existence of visual and functional connections between buildings and public open spaces and the use given to the ground floors. In "traditional urban form" the buildings have front doors and windows facing public streets, while in the "modernist urban form" buildings tend to have doors and windows distant from public streets and/or directed to internal open spaces in the block, without distinction between front and back doors and windows. Thus, examples of cities in different countries are used for comparisons and reflections involving these aspects. The main consequences of these analyzes reinforce the need for a better understanding on the implications of urban form for the use and aesthetics of urban spaces. Additionally, it is highlighted the importance of visual and functional connections between the ground floor and the public open spaces, to the vitality, safety and appearance of urban spaces.

Overview video diagnostics for the W7-X stellarator

Considering the requirements of the newly built Wendelstein 7-X stellarator a ten-channel overview video diagnostic system was developed and is presently under installation. The system covering the whole torus interior can be used not only to observe the plasma but also to detect irregular operational events which are dangerous for the stellarator itself and to send automatic warning for the machine safety. The ten tangential AEQ ports used by the diagnostic remain under atmospheric pressure, the vacuum/air interface is at the front window located at the plasma side of the AEQ port. The optical vacuum window is protected by a cooled pinhole. The Sensor Module (SM) of the intelligent camera (EDICAM) – developed especially for this purpose – is located directly behind the vacuum window. EDICAM is designed to simultaneously record several regions of interest of its CMOS sensor with different frame rate and to detect various predefined events in real time. The air cooled SM is fixed by a docking mechanism which can preserve the pointing of the view. EDICAM can withstand the magnetic field (∼3T), the neutron and gamma fluxes expected in the AEQ port. In order to adopt the new features of the video diagnostics system both control and data acquisition and visualization and data processing softwares are developed.

Tetrafluoroethane (R134a) hydrate formation within variable volume reactor accompanied by evaporation and condensation.

Vast size hydrate formation reactors with fast conversion rate are required for the economic implementation of seawater desalination utilizing gas hydrate technology. The commercial target production rate is order of thousand tons of potable water per day per train. Various heat and mass transfer enhancement schemes including agitation, spraying, and bubbling have been examined to maximize the production capacities in scaled up design of hydrate formation reactors. The present experimental study focused on acquiring basic knowledge needed to design variable volume reactors to produce tetrafluoroethane hydrate slurry. Test vessel was composed of main cavity with fixed volume of 140 ml and auxiliary cavity with variable volume of 0 ∼ 64 ml. Temperatures at multiple locations within vessel and pressure were monitored while visual access was made through front window. Alternating evaporation and condensation induced by cyclic volume change provided agitation due to density differences among water and vapor, liquid and hydrate R134a as well as extended interface area, which improved hydrate formation kinetics coupled with latent heat release and absorption. Influences of coolant temperature, piston stroke/speed, and volume change period on hydrate formation kinetics were investigated. Suggestions of reactor design improvement for future experimental study are also made.

Influence of wavelength-shifting films on multianode PMTs with UV-extended windows

Wavelength-shifting (WLS) films were applied on UV-extended front windows of multianode photomultiplier tubes (MAPMTs) in order to increase the sensitivity of the MAPMTs at shorter wavelengths. The WLS material contained p-Terphenyl as photoactive component, which absorbs shorter wavelength photons (<300nm) and re-emits fluorescence photons around 350nm, i.e., at the maximum of the PMTs׳ sensitivity. The films were applied by means of dip-coating and the film performance was studied with respect to quantum efficiency, film homogeneity, and crosstalk on the MAPMTs. Using WLS-film-covered MAPMTs in a gaseous Ring Imaging Cherenkov detector, the number of detected photoelectrons per ring increased by up to 21% in an in-beam test.

A lane detection approach based on intelligent vision

This paper proposes driver assistant system architecture based on image processing techniques. A camera is mounted on the vehicle front window to detect the road lane markings and determine the vehicle's position with respect to the lane lines. A modified approach is proposed to accelerate the HT process in a computationally efficient manner, thereby making it suitable for real-time lane detection. The acquired image sequences are analyzed and processed by the proposed system, which automatically detects the lane lines. The experimental results show that the system works successfully for lane line detection and lane departure prediction.

The Curve of the Smoke

The Curve of the Smoke Beth Newberry (bio) On a Thursday night in late June, the air is sticky on my skin as I smoke a cigarette at my kitchen window and watch the smoke curl into the air. It curves like my fingers do when I hold a pen. I stand at the open window and face the butter-colored aluminum siding of the building next to mine. I smoke a cigarette because I want one even though it doesn’t [End Page 74] provide the buzz or sensation of relief that I expect. The Marlboro Light rests just where a pen does—between the callus on my middle finger and the tip of my index finger. I look at my fingertips and then past my hand to the snail-shell-shaped circles of pigeon excrement on the paint-chipped windowsill. My cell phone rings and I stretch to reach it on the edge of the countertop as I try unsuccessfully to keep the cigarette smoke outside of the window. “Bethie,” my friend Alan cajoles. “Let’s go out.” The final word out has several symbols, as Alan expands the three letters with significant whining. I turn him down. “I have to write,” I say. “Just one drink. You’ll be home by midnight.” I think it over briefly as I consider my cigarette: Date with my friend, or date with my cigarette. “Can’t do it. How about tomorrow. After work?” I feel guilty as I end the call. And then I think, It’s okay. I’ll get the smoking out of my system tonight and go smoke-free tomorrow. Alan thinks I have quit. I thought I had quit, too. But I switched my social smoking habit for a private one. A habit-inducing trade off. I feel guilty for lying by omission, for stinking up my apartment, and for blatantly flaunting a disregard for the Surgeon General warnings about cancer, emphysema and the eternal damnation that smoking causes. I stand and think about the view from the front windows of my apartment, the activity of the sidewalk below: I’m not observing any of it at the moment, all I can see is the siding on the second story of the building next to mine that houses a Japanese restaurant. I close my eyes and listen to the sounds of customers talking on the restaurant’s patio, the bass line of the acid jazz music from the speakers, and the shifting of gears and acceleration of a car at the traffic light. I smell seaweed and sesame oil and exhaust and the ripeness of the summer heat. [End Page 75] I inhale a final drag and put out the cherry of the cigarette, like a miniature harvest moon disappearing in the horizon of chipped paint on the sill. I breathe out slowly and walk from the kitchen at the rear of my apartment to my desk, facing the street. I make my hands move across the keyboard before I can fully realize the cigarette is gone. On Friday morning, the half-full pack sits on the kitchen counter as I head to the coffee pot. I go to throw the cigarettes away, but put them in my purse instead. I feel a slight pain behind my rib, like the corroding of my lungs has deepened a layer. I don’t want to be a smoker, I think. I’m standing at my kitchen counter, adjacent to the smoking window. I’ve emptied the contents of my purse from the evening before: bar receipt, cigarettes, lighter, wallet, gum, and lip balm. A month ago, I started graduate school. A month before that I stopped smoking, and I lost the everyday taste for the cigarette. I stopped salivating when I heard the sound of the lighter. I forgot the satisfaction in the motion of the first drag and the last exhalation. I gladly moved away from the dirty kitchen window speckled with feathers, pigeon poop residue and pollen particles. So now, a month after the month I quit and relinquished my habit, I am smoking again. But why? It’s a habit that calms my racecar-speed...

December 2014: JoVE's Year in Review

In this Year in Review, we showcase some of our favorite video articles of the year 2014 in JoVE: The Journal of Visualized Experiments. In January, JoVE Chemistry revisited one of the most famous experiments of the 20th Century. Stanley Miller and his thesis advisor, Harold Urey, made scientific history in 1953 when they showed that under the right conditions, simple compounds in a flask could spontaneously form the building blocks of life. Over six decades later, Parker et al. have demonstrated how to recreate the classic Miller-Urey experiment-combining water with various gases, And subjecting the mixture to sparks to simulate Earth's conditions 3 ½ billion years ago. The resulting primordial soup contains various amino acids that are fundamental to life on earth. February's Neuroscience section featured the nematode worm C. elegans. This simple organism is easy to manipulate genetically. And it's sensitive to various compounds, so Hao and Buttner [scientists can] use them in chemical genetic screens to study the mechanisms of antipsychotic drugs. In March, JoVE Clinical and Translational Medicine had an article on amyotrophic lateral sclerosis (ALS). This neurodegenerative disease affected baseball legend Lou Gehrig, and in 2014, inspired millions of people to dump ice buckets on their heads to raise money and awareness for ALS. An early sign of ALS is weakness in specific hand muscles, so Menon and Vucic showed how recording motor responses from hand muscle groups can help diagnose this disease. April's edition of JoVE Environment featured a technique for expressing recombinant genes in plants. Mattozzi et al. delivered special expression constructs using a gene gun to specifically target recombinant genes to different subcellular organelles in plants. In May, JoVE Clinical & Translational Medicine, Thompson et al. used coordinate mapping to analyze the pharyngeal phase of swallowing, a technique that can be useful for studying swallowing disorders. In June, JoVE Applied Physics took us back in time again with a protocol that approximates conditions in the early Solar System. Blum et al. examined collision forces between particles, which can aggregate over hundreds of millions of years to form planets. In the July edition of JoVE Behavior, Tung et al. demonstrated standard behavioral tests for noninvasively assessing balance performance in mice. In August, Malide et al. demonstrated in JoVE Biology how to label hematopoietic precursor cells with different fluorescent markers so the cells can be tracked as they differentiate and engraft into bone marrow after transplantation. In our September issue, JoVE Bioengineering featured innovative methods for treating the cornea, the clear front window of the eye. Ortega et al. engineered membranes that could potentially regenerate the corneal epithelium and preserve vision in certain eye diseases. In October, JoVE Immunology & Infection featured a technique for analyzing glycoprotein spikes on viral surfaces, which many viruses use to penetrate host cells. Huiskonen et al. use a computational approach to study the precise, 3D structures of these spikes, which can guide the design of antiviral drugs and vaccines. November's edition of JoVE Biology took flow cytometry to a whole new level with a protocol that can be performed in space. Phipps et al. demonstrate the procedure on a parabolic flight, also known as a vomit comet, which creates a weightless environment and presents a whole new set of challenges to laboratory research. And coming up in December, we pinch off 2014 with a article describing fecal transplantation, When stool from a healthy donor is transferred to a patient infected with Clostridium difficile through a standard colonoscopy, it is a highly effective therapy for infections that don't respond to other treatments. This Year in Review was just a sampling of more than 900 video articles that JoVE produced for 2014. Browse the JoVE archives for thousands of other videos, and come back each week to see brand-new material in JoVE: The Journal of Visualized Experiments.

Monte Carlo calculations of electron beam quality conversion factors for several ion chamber types.

To provide a comprehensive investigation of electron beam reference dosimetry using Monte Carlo simulations of the response of 10 plane-parallel and 18 cylindrical ion chamber types. Specific emphasis is placed on the determination of the optimal shift of the chambers' effective point of measurement (EPOM) and beam quality conversion factors. The EGSnrc system is used for calculations of the absorbed dose to gas in ion chamber models and the absorbed dose to water as a function of depth in a water phantom on which cobalt-60 and several electron beam source models are incident. The optimal EPOM shifts of the ion chambers are determined by comparing calculations of R50 converted from I50 (calculated using ion chamber simulations in phantom) to R50 calculated using simulations of the absorbed dose to water vs depth in water. Beam quality conversion factors are determined as the calculated ratio of the absorbed dose to water to the absorbed dose to air in the ion chamber at the reference depth in a cobalt-60 beam to that in electron beams. For most plane-parallel chambers, the optimal EPOM shift is inside of the active cavity but different from the shift determined with water-equivalent scaling of the front window of the chamber. These optimal shifts for plane-parallel chambers also reduce the scatter of beam quality conversion factors, kQ, as a function of R50. The optimal shift of cylindrical chambers is found to be less than the 0.5 rcav recommended by current dosimetry protocols. In most cases, the values of the optimal shift are close to 0.3 rcav. Values of kecal are calculated and compared to those from the TG-51 protocol and differences are explained using accurate individual correction factors for a subset of ion chambers investigated. High-precision fits to beam quality conversion factors normalized to unity in a beam with R50 = 7.5 cm (kQ (')) are provided. These factors avoid the use of gradient correction factors as used in the TG-51 protocol although a chamber dependent optimal shift in the EPOM is required when using plane-parallel chambers while no shift is needed with cylindrical chambers. The sensitivity of these results to parameters used to model the ion chambers is discussed and the uncertainty related to the practical use of these results is evaluated. These results will prove useful as electron beam reference dosimetry protocols are being updated. The analysis of this work indicates that cylindrical ion chambers may be appropriate for use in low-energy electron beams but measurements are required to characterize their use in these beams.

Synthesis of sol–gel derived nano-crystalline ZnO thin films as TCO window layer: effect of sol aging and boron

The present paper reports synthesized nano-sized ZnO thin films for use as front window electrodes in PV applications, and their behavior after different sol aging times (1 h, 24 h, 3 days and 21 days) for undoped and 1% B amount doping. The highly nanocrystalline ZnO thin films were synthesized by the sol–gel method and B was used as a guest material to examine its role in structural, optical, electrical and morphological properties in this process. X-ray diffraction studies revealed that all the prepared films exhibited the ZnO hexagonal wurtzite structure with preferential orientation along the (0 0 2) crystal plane. Analyses of X-ray diffraction patterns demonstrated that the sol aging can improve the degree of preferred crystal orientation along the c-axis, and it did not change the crystal growth orientation. Average crystallite sizes of the undoped and B doped ZnO films were increased from 16 to 31 nm and from 19 nm to 32 nm with increasing sol aging from 1 h to 21 days. Moreover, AFM results showed that the RMS values increased from 5 nm to 12 nm as an indication of a good film formation on the surface. The minimum value of resistivity was found to be 7.24 × 10−3 Ω m with B and a high optical transmittance of ∼98% in the visible region was observed. The films produced at optimum conditions are suitable for optical and electrical applications owing to their low resistivity, high optical transmittance, optimum band gap, good crystallization and surface formation.