Flash Exposure Research Articles

Microstructural effects of copper deposits on direct bonding for 3D IC integration

Cu-to-Cu direct bonding has been regarded as an important approach to achieve three-dimensional integrated circuit integration. This study aims to investigate the effects of microstructure and Xenon flash exposure on the direct bonding of copper deposits. Copper electrodeposits, along with a sputtered deposit, with various grain sizes, preferred orientations, as well as surface hardnesses, were prepared to clarify the influence of individual factors quantitatively. Experimental results show that joint strength and grain boundary density followed a positively linear relationship regardless of other microstructural differences, suggesting the dominating role of grain boundary diffusion. Grain refinement can effectively enhance bonding strength, even only one side of the directly bonded joints possessed fine grains. Considering the portable device applications which may suffer from drop shocks, drop testing of the packages comprising sputtered copper on Si chips joined with electroplated copper on Al2O3 substrates assembled by thermal compression bonding was performed for the first time. Noticeably, a proper flash irradiaiton prior to bonding brought about not only remarkable improvement in shear strength by up to 60 % but also drop resistance for direct-copper bonds. The resistance against drop shock for directly-bonded daisy chains subjected to an appropriate light exposure prior to bonding was superior than the joints bonded using impact-resistant solders.

0315 Phase shifting in response to light flash sequences during sleep

Abstract Introduction The human circadian clock is synchronized to the outside world through regular ocular light exposure. Light does not need to be continuous to be an effective time cue. Light administered as a sequence of light flashes can be more effective than continuous light of the same illuminance. Exposure to a sequence of light flashes while awake is annoying, but such exposure can occur during sleep, without disrupting sleep, when the circadian system is most sensitive to light. As such, the purpose of this experiment was to determine the magnitude of circadian phase shift that could be obtained when exposing individuals to light flash sequences during sleep. Methods Healthy young individuals (n=10) participated in a crossover study of two separate 16-d protocols, the order of which was randomized. The first 14 d were an at-home circadian phase/amplitude optimization period, followed by a 37-h in-laboratory stay during which participants had constant routines (CR) on two consecutive evenings. The onset of salivary melatonin determined during the CRs was used as a marker of circadian phase. Light was dim (< 5 lux) or dark between CRs, except for the light flashes (2-ms flashes, ~1500 lux, every 15 s for 1 h) that were administered via custom goggles while participants slept (starting 30 m after habitual bedtime). During the placebo condition, the goggles provided no light. The impact of the light on circadian phase (pre-post) and polysomnographically-measured sleep were assessed. Results As compared to the control condition (12±20 minutes), exposure to the flashes engendered substantial shifts (1.13±1.27 h, p< 0.01; d=1.02). There was considerable variability in response to the stimulus, with two individuals not displaying any phase changes, three having a modest phase change (< 1 hour), two having a moderate phase change (1-2 hours) and two having a large phase shift (>2 hours), one of whom shifted more than 6 hours. There were no significant differences in sleep on placebo or flash exposure nights. Conclusion Exposure to a sequence of light flashes during sleep has the capacity to engender large changes in circadian timing without necessitating behavior changes during wake to receive phototherapy. Support (if any) Department of Defense (W81XWH-16-1-0223)

DNA strand break induction of aqueous plasmid DNA exposed to 30 MeV protons at ultra-high dose rate.

Radiation cancer therapy with ultra-high dose rate exposure, so called FLASH radiotherapy, appears to reduce normal tissue damage without compromising tumor response. The aim of this study was to clarify whether FLASH exposure of proton beam would be effective in reducing the DNA strand break induction. We applied a simple model system, pBR322 plasmid DNA in aqueous 1 × TE solution, where DNA single strand breaks (SSBs) and double strand breaks (DSBs) can be precisely quantified by gel electrophoresis. Plasmid DNA were exposed to 27.5 MeV protons in the conventional dose rate of 0.05 Gy/s (CONV) and ultra-high dose rate of 40 Gy/s (FLASH). With both dose rate, the kinetics of the SSB and DSB induction were proportional to absorbed dose. The SSB induction of FLASH was significantly less than CONV, which were 8.79 ± 0.14 (10−3 SSB per Gy per molecule) and 10.8 ± 0.68 (10−3 SSB per Gy per molecule), respectively. The DSB induction of FLASH was also slightly less than CONV, but difference was not significant. Altogether, 27.5 MeV proton beam at 40 Gy/s reduced SSB and not DSB, thus its effect may not be significant in reducing lethal DNA damage that become apparent in acute radiation effect.

Modeling of cellular response after FLASH irradiation: a quantitative analysis based on the radiolytic oxygen depletion hypothesis

Purpose. Recent studies suggest ultra-high dose rate (FLASH) irradiation can spare normal tissues from radiotoxicity, while efficiently controlling the tumor, and this is known as the ‘FLASH effect’. This study performed theoretical analyses about the impact of radiolytic oxygen depletion (ROD) on the cellular responses after FLASH irradiation. Methods. Monte Carlo simulation was used to model the ROD process, determine the DNA damage, and calculate the amount of oxygen depleted (L ROD) during FLASH exposure. A mathematical model was applied to analyze oxygen tension (pO2) distribution in human tissues and the recovery of pO2 after FLASH irradiation. DNA damage and cell survival fractions (SFs) after FLASH irradiation were calculated. The impact of initial cellular pO2, FLASH pulse number, pulse interval, and radiation quality of the source particles on ROD and subsequent cellular responses were systematically evaluated. Results. The simulated electron L ROD range was 0.38–0.43 μM Gy−1 when pO2 ranged from 7.5 to 160 mmHg. The calculated DNA damage and SFs show that the radioprotective effect is only evident in cells with a low pO2. Different irradiation setups alter the cellular responses by modifying the pO2. Single pulse delivery or multi-pulse delivery with pulse intervals shorter than 10–50 ms resulted in fewer DNA damages and higher SFs. Source particles with a low linear energy transfer (LET) have a higher capacity to deplete oxygen, and thus, lead to a more conspicuous radioprotective effect. Conclusions. A systematic analysis of the cellular response following FLASH irradiation was performed to provided suggestions for future FLASH applications. The FLASH radioprotective effect due to ROD may only be observed in cells with a low pO2. Single pulse delivery or multi-pulse delivery with short pulse intervals are suggested for FLASH irradiation to avoid oxygen tension recovery during pulse intervals. Source particles with low LET are preferred for their conspicuous radioprotective effects.

The Possibilities to Reduce Arc Flash Exposure with Arc Fault Eliminators

This paper presents a method to limit the arc energy and hence the hazard risk category value according to IEEE 1584 by using a system of two oppositely connected multi-sectional thyristor branches. A test circuit for testing the effectiveness of a thyristor arc eliminator was designed and constructed. Arc ignition inside electrical switchgear can be a source of danger for technical personnel. The arc energy calculated according to the algorithms in IEEE 1584 can be significantly reduced by using multi-sectional arc eliminator MSAE. For the actual measuring object, the calculation of the hazardous arc flash zone and the hazard category was carried out for the system not equipped with an arc eliminator, and then the same was performed in a system with an arc eliminator. In parallel, the pressure inside the closed polyvinyl chloride (PVC) electrical box enclosure was measured and then compared with the calculated pressures that could occur during an arc fault. It was found that a Multi-Sectional Arc Eliminator (MSAE) effectively protects devices supplied from low voltage networks against the effects of short circuit or arc fault, such as the sudden increase of gas pressure inside the switchboard, which may cause it to break, significantly reduce the loss of electrode material, limit the spread of hot electrode material outside the switchgear, and also significantly reduces the energy of the electric arc.

Impact of SRFE process on electrical properties of P-N photodetector

Semiconductor properties change from soft radiation flash exposure process (SRFE) will present in this paper. Semiconductor device use with radiation application and always degrade because impact from radiation will damage on device structure. Currently, the defects from radiation cannot explain all of impact to electrical properties because has wind range in several application. However, this paper will present influent from Roentgen radiation on P-N photodetector device by expose for few second and low energy. The radiation will expose on device for many time to reach target time and will control distance between radiations machine and devices. Forward current of device after SRFE process has changed in positive way by build in potential (Vbi) decrease around 0.2V and forward current increase around 4 orders.

A novel to control defects of P-N semiconductor device by SRFE process

This paper present the results from soft radiation flash exposure (SRFE) process. In principle of semiconductor device always has defect in structure from fabrication process and impact from usage environment. Although, device have control process but still has unexpected defects. Then, I would like to share results of SRFE process to control defects in P-N semiconductor device by exposed on device for few second with optimize radiation energy. The defects has disappear after passed SRFE process. The optimize of exposure energy and time will cure or remove defect in devices structure.

The Effect of a Photochromic Contact Lens on Visual Function Indoors: A Randomized, Controlled Trial.

SIGNIFICANCEPhotochromic soft contact lenses contain light-sensitive additives that allow them to darken when exposed to ultraviolet or violet light. One question, however, is whether the lenses influence vision indoors (minimally activated). In this study, we found that the minimally activated lenses improved many aspects of visual function under bright light.PURPOSEPhotochromic contact lenses were designed to darken when exposed to outdoor sunlight. The filtering that results improves visual function under bright light conditions. Not all bright light exposures occur outdoors. In this study, we tested whether a photochromic contact lens improved visual function under conditions where the lens was minimally activated (i.e., no more than it normally would be in an indoor environment).METHODSA subject-masked contralateral design was used comparing a photochromic contact lens randomized to one eye against a nonphotochromic contact in the other eye of the same subject. Sixty subjects (mean = 34.90 ± 11.24 years) were tested. The primary endpoints consisted of four visual function outcomes: photostress recovery, glare disability, glare discomfort, and chromatic contrast. Photostress recovery was quantified by measuring the time needed to recover visual acquisition of a grating target after 5 seconds of an intense xenon white flash exposure; glare disability was evaluated as the energy in a surrounding xenon white annulus necessary to veil a central grating target; and glare discomfort was assessed using bioimaging of the squint response. Chromatic contrast was measured as thresholds for a green-yellow (580 nm) grating target superposed on a blue (460 nm) background.RESULTSThe minimally activated photochromic contact demonstrated improved visual performance compared with the nonphotochromic control across all visual functions tested (P < .01).CONCLUSIONSEven under conditions of exiguous activation (e.g., as would be expected indoors or while driving at night), a photochromic contact will improve many of the more deleterious aspects of bright light.

Leakage Current in P N Junction Diode by Influent from SRFE Process

This paper present the effect from soft radiation flash exposure (SRFE) on electrical properties of semiconductor device. SRFE process take only few second on semiconductor device but it quite impact to device performance. The part we will study impact from SRFE such as surface and bulk. COMSOL is tool for help to understand more detail in term of surface recombination, temperature and bulk effect. Surface of device get impact from radiation and temperature generate from radiation. Also, silicon bulk get damage from radiation due to has high penetrate. From electrical results show that leakage current of device has reduce after SRFE process, mean radiation can help to improve or recover damage from fabrication process.

Surface Thermal and Electric charge of PN Diode Expose by Soft Radiation Flash Exposure

In this study present the effect of soft radiation flash exposure (SRFE) to forward bias current-voltage (I-V) of PN diode by using COMSOL simulation program. The results show surface thermal and electric change while expose by radiation with flash exposure technique. Series resistance (Rs) increase around 2 times and close to idea case after expose by radiation, the radiation will impact to bulk defect and reduce surface recombination. SRFE induce temperature on surface and deep into silicon bulk. The value of Rs increase with increase expose time. The changing of Rs becomes independent from radiation dose at high forward bias voltage.

Investigation the Effect of Soft X-ray Flash Exposure on PN Diode

In this paper will present the properties of PN diode before and after expose by radiation. Although, radiation help to improve the performance of semiconductor device but still has some damage in device structure. In previous article I have showed performance improve after expose by soft radiation. The device is exposed by low frequency X-ray radiation (soft radiation flash exposure: SRFE) technique with few second for several times. In principle of PN diode after fabrication will has defects from process such as ion implantation, doped and silicon wafer process. The results show temperature while SRFE expose on device that generate high temperature on surface and silicon boundary that may the optimize energy and expose time for treatment damage of PN diode.

A contra-lateral comparison of the visual effects of a photochromic vs. non-photochromic contact lens

PurposeTo compare the effects of a photochromic contact lens vs. a non-photochromic control lens on visual function. MethodsA subject-masked, prospective contralateral eye design was used. Sixty-one subjects were enroled based on age (using a 2:1 allocation ratio for ages 18–39 and 40–65 years, respectively). The study lenses were senofilcon A with photochromic additive (Test) that filtered over the entire lens, compared to a non-photochromic Control with no tint. The Test lens was partially activated during testing with a steady-state transmittance of approximately 62%. Eligible subjects were tested using both study lenses, with Test and Control lens randomized by eye. Five visual function outcomes were tested: photostress recovery (PSR), glare disability (GD), glare discomfort (GDC), chromatic contrast (CC) and vernier acuity (VA). Iris colour and macular pigment density were assessed as control variables. PSR was measured as the time needed to recover sight of a target after an intense xenon flash exposure; GD was evaluated as the energy needed to veil a central target by a surrounding xenon annulus; GDC was measured using bio-imaging of the squint response and by self-report using a 9-item Likert scale; CC was measured as thresholds for a yellow grating target superposed on a 460-nm background; VA was determined by measuring vernier offsets of light lines through apertures. ResultsBased on our stimulus conditions, PSR was 43% faster using the Test vs. the Control. The eye wearing the Test had 38% less squint (GDC) compared to the Control. GD was improved by 36% in the Test vs. Control and CC was enhanced by 48% with the Test. There was no significant difference in VA. ConclusionsThere was a beneficial influence on visual function when comparing the photochromic with the non-photochromic contact lens. This benefit was seen specifically with respect to PRT, GDC, GD and CC thresholds.

High-fidelity 3D printing using flashing photopolymerization

Photopolymerization-based 3D printing has emerged as a promising technique to fabricate 3D structures. However, during the printing process, polymerized materials such as hydrogels often become highly light-scattering, thus perturbing incident light distribution and thereby deteriorating the final print resolution. To overcome this scattering-induced resolution deterioration, we developed a novel method termed flashing photopolymerization (FPP). Our FPP approach is informed by the fundamental kinetics of photopolymerization reactions, where light exposure is delivered in millisecond-scale ‘flashes’, as opposed to continuous light exposure. During the period of flash exposure, the prepolymer material negligibly scatters light. The material then polymerizes and opacifies in absence of light, therefore the exposure pattern is not perturbed by scattering. Compared to the conventional use of a continuous wave (CW) light source, the FPP fabrication resolution is improved. FPP also shows little dependency on the exposure, thus minimizing trial-and-error type optimization. Using FPP, we demonstrate its use in generating high-fidelity 3D printed constructs.

Enhanced Photothermal Effect in Ultralow-Density Carbon Aerogels with Microporous Structures for Facile Optical Ignition Applications.

The exact mechanism responsible for the phenomenon known as photoignition with an enhanced photothermal effect in high-surface-area carbon with the addition of a metal catalyst is an open issue. Here, we report the first successful flash ignition of a pure carbon material in ambient air microporous carbon aerogels (CAs) with ultralow density and high surface area. Under flash exposure, the CAs show a strong local heat confinement effect near microporous structures (0.6-2 nm), and the graphite crystallite structures existing in single carbon nanoparticles (∼15 nm) are damaged. The local heat confinement effects are mainly derived from the low gaseous thermal conductivity in micropores and low solid thermal conductivity in low-density CAs. In addition, the limiting effects of the microporous structure on the vibration amplitude of free-state electrons in low-density CAs result in a dramatic increase in optical absorption. Numerical simulations of unsteady temperature fields of CAs with different densities and thicknesses are also performed, and the calculated maximum temperature of a 17 μm-thick 20 mg/cm3 CA bed is 1782 °C. CAs with higher density can also give rise to enhanced photothermal response and ignition with the addition of metal Fe nanoparticles. The metal catalyst increases both the light absorption capacity in the visible-light range and the heat accumulation capacity. These results are important for understanding the mechanism of flash ignition, especially the local high temperature and effects of metal catalyst in carbon materials during the photothermal process.

Effect of moisture content on thermal protective performance of fabric assemblies by a stored energy approach under flash exposure

Firefighters wearing protective clothing perspire profusely in the process of performing their duties, and sweat increases moisture in the inner layers of multilayer protective clothing. Also, the outer shell fabrics inevitably become wet. In this study, two kinds of outer shell fabrics (aramid IIIA fabric and aramid 1313 and flame-retardant viscose-blended fabric) and three kinds of thermal liner fabrics with different thicknesses were selected. Two wetness conditions were investigated to simulate the sweating in thermal liner fabric with or without the wet outer shell fabric. A modified thermal protective performance (TPP) tester was employed to explore the effects of moisture and its distribution on stored thermal energy developed in six fabric systems and on TPP under flash exposure. Pearson correlations were established to analyze the relationships of the fabric systems’ thickness and second-degree burn time, and of absorbed energy and second-degree burn time in different configurations. The statistical analysis from these obtained data indicated that the thickness of fabric systems had no significant correlation for second-degree burn time ( p &gt; 0.05), but the absorbed energy exhibited a strong relation (the lowest R2 value could reach 0.8070 and p-values were all much less than 0.05). Performance results for the wet thermal liner indicated that the negative impact on thermal protection reached the greatest degree in 15% wetness, but in some extreme situations (100% wetness), the performance was improved (the maximum increase can achieve 116.2% over performance in dry condition). However, the existing moisture in the outer shell showed a positive effect. These findings will enable the engineering of textile materials that achieve high performance protection from thermal hazards and give some guidance to firefighters during operations.

"Know What to Do If You Encounter a Flash Flood": Mental Models Analysis for Improving Flash Flood Risk Communication and Public Decision Making.

Understanding how people view flash flood risks can help improve risk communication, ultimately improving outcomes. This article analyzes data from 26 mental models interviews about flash floods with members of the public in Boulder, Colorado, to understand their perspectives on flash flood risks and mitigation. The analysis includes a comparison between public and professional perspectives by referencing a companion mental models study of Boulder-area professionals. A mental models approach can help to diagnose what people already know about flash flood risks and responses, as well as any critical gaps in their knowledge that might be addressed through improved risk communication. A few public interviewees mentioned most of the key concepts discussed by professionals as important for flash flood warning decision making. However, most interviewees exhibited some incomplete understandings and misconceptions about aspects of flash flood development and exposure, effects, or mitigation that may lead to ineffective warning decisions when a flash flood threatens. These include important misunderstandings about the rapid evolution of flash floods, the speed of water in flash floods, the locations and times that pose the greatest flash flood risk in Boulder, the value of situational awareness and environmental cues, and the most appropriate responses when a flash flood threatens. The findings point to recommendations for ways to improve risk communication, over the long term and when an event threatens, to help people quickly recognize and understand threats, obtain needed information, and make informed decisions in complex, rapidly evolving extreme weather events such as flash floods.

Arc Flash Calculations for a 1.3-MW Photovoltaic System

When planning for the installation of a 1.3MW photovoltaic system, and its integration into an existing facility's electrical system, an arc flash study was performed to determine the best protective device settings to minimize the arc flash energy in the photovoltaic system, and to determine the effect of the additional short circuit current on the existing system arc flash calculations. The existing system has distribution at 13.8kV and two 10MVA transformers to a 2.4kV feeder system. The photovoltaic system adds the hazard of 500 VDC sub-array collection wiring and terminations. The DC arc flash exposure of PV systems, including those in the inverter enclosures, can be complicated, and this paper outlines the basic data collected for the study, the steps taken to complete the calculations, the methodology used, the results, and the team's learnings.

A double-blind, placebo-controlled study on the effects of lutein and zeaxanthin on photostress recovery, glare disability, and chromatic contrast.

Past studies have shown that higher macular pigment optical density (MPOD) and lutein (L) and zeaxanthin (Z) supplementation are related to improvements in glare disability, photostress recovery, and chromatic contrast. This study assessed those links using a randomized, double-blind, placebo-controlled design. The visual effects of 1 year of supplementing L (10 mg/d) and Z (2 mg/d) were investigated. One hundred fifteen young, healthy subjects were recruited and randomized into the study (58 received placebo, 57 L+Z). Several dependent measures were collected at baseline and then once every 3 months: serum L and Z measured by HPLC chromatography; MPOD measured using customized heterochromatic flicker photometry; photostress recovery assessed by measuring the time needed to recover visual acquisition of a grating target after 30 seconds of an intense xenon white flash exposure; glare disability evaluated as the energy in a surrounding annulus necessary to veil a central grating target; and chromatic contrast assessed by measuring thresholds for a yellow grating target superposed on a 460-nm background. Macular pigment optical density increased significantly versus placebo at all eccentricities (10, 30, 60, and 105 minutes from the center of the macula). Serum L and Z also increased significantly by the first follow-up visit (at 3 months), and remained elevated throughout the intervention period of 1 year. Chromatic contrast and photostress recovery time improved significantly versus placebo. Glare disability was correlated with macular pigment density throughout the study period but did not increase significantly in the treated group. Daily supplementation with L+Z resulted in significant increase in serum levels and MPOD and improvements in chromatic contrast and recovery from photostress. These results are consistent with past studies showing that increasing MPOD leads to improved visual performance. (ClinicalTrials.gov number, NCT00909090.).

On the evolution of cured voxel in bulk photopolymerization upon focused Gaussian laser exposure

Unconstrained depth photopolymerization is emerging as a promising technique for fabrication of several polymer microstructures such as self propagating waveguides, 3D freeform structures by bulk lithography, and polymer nanoparticles by flash exposure. Experimental observations reveal governing physics beyond Beer Lambert's law and scattering effects. This paper seeks to model unconstrained depth photopolymerization using classical nonlinear Schrödinger equation coupled with transient diffusion phenomenon. The beam propagation part of the proposed model considers scattering effects induced due to spatial variation of the refractive index as a function of the beam intensity. The critical curing energy model is used to further predict profile of polymerized voxel. Profiles of photopolymerized voxel simulated using proposed model are compared with the corresponding experimental results for several cases of exposure dose and duration. The comparison shows close match leading to conclusion that the experimentally observed deviation from Beer Lambert's law is indeed due to combined effect of diffusion of photoinitiator and scattering of light because of change in the refractive index.

The Fluoroscopic Technique for Monitoring Distraction of a Non-Invasive Lengthening Device in Early Onset Scoliosis

Study Design: Prospective non-randomised. Objective: To evaluate radiation exposure using fluoroscopy compared to x-rays in the monitoring of a growing rod system. Background: The integrity of implants in the treatment of early onset scoliosis (EOS) is usually monitored with repeated plain x-rays. The cumulative dosage of ionizing radiation may be high. Children are highly sensitive to the carcinogenic effects of radiation and have a longer life span in which to reflect this risk. Fluoroscopy is commonly used to obtain focused images in other areas of orthopaedics. It has the advantage of less radiation intensity due to flash exposure. We have used fluoroscopy to monitor the lengthening of a non-invasive growing rod system in the treatment of EOS. We report on the results. Methods: The technique was initially refined in vitro by performing an audit in which 10 radiographers screened a phantom spine (Plastic dummy) with an implanted non - invasive growing rod device. Pulse rate setting was 3. Average exposure time was 0.01 seconds. Average radiation dose was 0.04 μGym2. A plain x-ray of the same phantom spine yielded a radiation dose of 0.5 μGym2. Radiation exposure using fluoroscopy was compared to that received using plain radiographs in ten consecutive patients treated for EOS. There were 8 males and 2 females. Average age 5.2 years. Results: Mean radiation exposure using fluoroscopy was 0.0046 mSv compared to an average radiation exposure of 0.115 mSv using standard x-rays (p&lt;0.003). Mean cancer induction risk was calculated to potentially reduce from 1:225,000 to 1:4.9 million. Conclusion: We would recommend fluoroscopy as a useful technique to monitor the lengthening of a non-invasive growing rod system due to the significantly smaller radiation exposure.