Shorter Effective Length Research Articles

Delivery of α-Particles By a Human-Rat Chimeric CD82 Monoclonal Antibody Potently Inhibits the Proliferation of CD82-Expressing Acute Myeloid Leukemia Cells in a Murine Xenograft Model

[Background] We previously found that acute myeloid leukemia (AML) cells aberrantly express CD82, a member of the tetraspanin family, on their surface. Functional analyses of CD82 by either depletion or forced expression of CD82 revealed that CD82 plays a role in the adhesion of AML cells to the bone marrow microenvironment in association with the inhibition of matrix metallopeptidase 9 (IJC 2013). In addition, CD82 transactivates several signaling pathways and upregulates anti-apoptotic Bcl-2L12 molecules in AML cells (Ikezoe T, et al. Int J Cancer. 2014;134:55, PLoS One. 2015;10: e0125017, Leukemia 2015;29:2296, Canc Sci. 2017;108:685). Alpha particle-emitting radionuclides are very attractive for cancer therapy, especially for micrometastases and isolated cancer cells commonly observed in leukemia, because of their high linear energy transfer and short effective path length in tissues. Astatine-211 ( 211At), with an appropriate half-life (7.2 hours), emits α-particles with higher energy in a shorter distance than ß-particles. It is ideal for cancer therapy through targeting tumor cells with α-particles by breaking double-stranded DNA while minimizing damage to normal cells. We have recently generated 211At-labeled human-rat chimeric CD82 monoclonal antibody ( 211At-h/r CD82 mAb) to deliver α-particles to CD82-expressing AML cells. [Aims] We conducted this study to evaluate the efficacy of a treatment strategy targeting CD82-expressing AML cells with 211At-h/r CD82 mAb. [Methods] Immunohistochemical staining was conducted to evaluate the binding of h/r CD82 mAb to U937 AML cells. 211At was produced by 209Bi(α, 2n) 211At nuclear reactions using an cyclotron (MP-30, Sumitomo Heavy Industries Ltd., Tokyo, Japan) at our institution, and h/r CD82 mAb was radiolabeled as described in our previous report (Oriuchi N, et al. Sci Rep. 2020;10:6810). A high-level CD82-expressing human AML cells xenograft (U937) was established in nude mice. In the biodistribution study, the mice were intravenously injected with 0.25 MBq of 211At-h/r CD82 mAb, and sacrificed at 1 min, 1, 3, 6, and 24 h after the injections (n=3 in each group). Blood, organs, and tumor tissues were collected, weighed, and measured for radioactivity using a gamma counter. The radioactivities of the blood, organs, and tumor tissues are presented as percent injected radioactivity dose per gram (%ID/g). In the treatment study, the mice were randomly divided into a nontreated (control, n=3) and two treated groups after the formation of palpable tumors. The mice in the treated groups were intravenously injected with either non-radiolabeled h/r CD82 mAb (h/r CD82 mAb, n=5) or 63.6 MBq of 211At-h/r CD82 mAb (n=4) on day 0. The tumor size of each mouse was measured daily until day 40 treatment. When the surface of the tumor tissue ruptured or the tumor diameter exceeded 20 mm, the tumor size measurement was stopped, and the mice were euthanized. [Results] Dense staining of CD82 by h/r CD82 mAb in a block of U937 cells was confirmed by immunohistochemical staining. The uptake levels of 211At-h/r CD82 mAb in the tumor significantly increased over time, which were 1.3 ± 0.3%ID/g, 6.3 ± 0.4%ID/g, 8.4 ± 2.0%ID/g, and 8.7 ± 0.8%ID/g at 1 min, and 1, 3, and 6 h after the injection, respectively. The highest tumor uptake level was achieved 6 h after the injection. This study revealed that the tumor volume significantly increased over time in the control and h/r CD82 mAb groups (from 106.9±36.6 mm 3 on day 0 to 4195 ± 1359.7 mm 3 on day16 in the control group, p<0.001; from 115.5 ± 11.7 on day 0 to 4045.5 ± 1912.1 mm 3 on day16 in the h/r CD82 mAb group, p<0.001). There was no significant difference in tumor volume between the control and h/r CD82 mAb groups. In contrast, the tumor volume significantly decreased over time after treatment with 211At-h/r CD82 mAb until day 10 (from 200.9±44.4 mm 3 on day 0 to 45.0 ± 60.5 mm 3 on day10, p<0.001 vs control and h/r CD82 mAb groups). Notably, two mice had no palpable tumor on day 45, indicating complete elimination of AML cells. [Conclusion] Delivery of α-particles by h/r CD82 mAb to CD82-expressing AML cells may be a promising strategy to overcome this lethal disease.

Quasi-Static Modelling of a Full-Channel Effective Magnetorheological Damper with Trapezoidal Magnetic Rings.

Magnetorheological damper (MRD) has been successfully applied to vehicle suspension systems as an intelligent core component. Most conventional MRDs have closed rectangle-shaped magnetic circuits, resulting in a short effective working length and negligible damping force. To address the above issues, a novel full-channel effective MRD with trapezoidal magnetic rings (FEMRD_TMR) is proposed. The trapezoidal magnetic ring can shunt the magnetic circuit, distributing it evenly along the damping channel and increasing the effective working length. Additionally, which has the same variation trend as the magnetic flux through it, makes the magnetic induction intensity distribution more uniform to reduce the magnetic saturation problem. Theoretically analyzing the damping characteristics of the FEMRD_TMR, a quasi-static model is developed to forecast the output damping force. The structural design of MRD is challenging since conventional quasi-static models rely on the yield stress of magnetorheological fluid (MRF) to reflect the rheological property, which cannot be directly observed and is challenging to calculate. The Takagi-Sugeno (T-S) fuzzy neural network and a unique magnetic circuit computation are offered as a novel quasi-static modeling approach to address the issue. The MRF's yield stress is linearized into magnetic induction intensity functions by the T-S fuzzy neural network and then converted into the MRD's structural size by the special magnetic circuit calculation. Therefore, the proposed quasi-static model can directly reflect the relationship between the damping force and structure size, simplifying MRD's structure design. The novel quasi-static model is shown to be more straightforward and understandable than the conventional Bingham quasi-static model and to have approximately accurate damping force prediction when compared to experimental data.

Effect of adverse slope on performance of USBR II stilling basin

Abstract This article focuses on the United States Bureau of Reclamation (USBR) Type II stilling basin, which has chute blocks, an end dentated sill, and a flat floor. USBR provides general design criteria to contain the hydraulic jump within the stilling basin. The sequent depth ratio, energy dissipation ratio, and stilling basin dimensions of the hydraulic jump are changed when the bed slope of USBR II stilling basins is changed. This study aimed to investigate the effects of adverse slope on the performance of USBR II stilling basin in terms of sequent depth ratio and energy dissipation. Six discharges ranging from 8 to 33 lps were applied to the USBR II stilling basin with bed slopes (S) of −0.085, −0.055, −0.035, and 0. Results demonstrated that for Q = 13 and 8 lps, the basin performs better than other models with S = −0.085, increasing energy dissipation by about 10% compared to a typical basin due to the formation of a free hydraulic jump downstream dentated end sill. On the other hand, the floor downstream of the dentated end sill needs more protection against this free jump, and this case becomes economically expensive. In other cases, the downstream jump was submerged, resulting in a counterintuitive current and reverse roller based on the submerged ratio, reducing the effectiveness of the stilling basin. In addition, the modified design of the stilling basin resulted in a shorter effective length that included the hydraulic jump downstream spillway, thereby reducing internal friction. As a result, the standard USBR II with a flatbed is less expensive and more efficient than the adverse slope basin.

Developing a misalignment model for folded optical resonators and designing a kilowatt-class disk laser resonator with a short effective length

In this article, a formulation was developed for designing a stable disk laser resonator and achieving a high power and a beam quality close to the fundamental mode with a short effective length. In this regard, by taking a matrix approach and using Gaussian beam propagation based on the ABCD law for Gaussian beams, the fundamental-mode spot size inside a resonator and its sensitivity to misalignment, as well as dynamic stability in multiple folded resonators, were analyzed in order to achieve a short effective length. In the presented method, the optimal geometrical parameters of the resonator were obtained by applying the length limits, permissible level of sensitivity to misalignment, and range of dynamic stability with the help of MATLAB software coding. Using this design algorithm, a Z-shaped resonator with the arm length of 50 cm and fundamental-mode spot size of 2.4 mm on the active media was designed, while the resonator had a good dynamic stability and low sensitivity to misalignment. Considering these specifications, it was possible to design a compact disk laser with a power of 1 kW, which had a beam quality close to the fundamental mode.To the best of our knowledge, the laser disk resonator described in this paper, which is resistant to misalignment and has a short effective length, has not been previously documented in the literature. The model developed in this research is a general model that can be used in much more complex structures with any numbers of optical elements in other lasers.

Monitoring of circulating amino acids in patients with pancreatic cancer and cancer cachexia using capillary electrophoresis and contactless conductivity detection.

Branched chain amino acids (BCAAs), alanine and glutamine are determined in human plasma by capillary electrophoresis with contactless conductivity detection (CE/C4 D). The baseline separation of five amino acids from other plasma components is achieved on the short capillary effective length of 18cm in 3.2mol/L acetic acid with addition of 13% v/v methanol as background electrolyte. Migration times range from 2.01min for valine to 2.84min for glutamine, and LODs for untreated plasma are in the interval 0.7-0.9μmol/L. Sample treatment is based on the addition of acetonitrile to only 15μL of plasma and supernatant is directly subjected to CE/C4 D. Circulating amino acids are measured in patients with pancreatic cancer and cancer cachexia during oral glucose tolerance test. It is shown that patients with pancreatic cancer and cancer cachexia syndrome exhibit low basal circulating BCAAs and glutamine levels and loss of their insulin-dependent suppression.

Microwave photonics interrogation for multiplexing fiber Fabry-Perot sensors.

A microwave photonics interrogation system for multiplexing fiber Fabry-Perot (FP) sensors is demonstrated in this paper. Different from previous FP demodulation schemes, this system aims at quasi-distributed sensing networks composed of FP sensors with a short effective cavity length less than 1 mm. With the help of a dispersion element, the superimposed reflected spectrum from FP sensors based on a hollow core fiber (HCF) can be converted into separate response passbands in the frequency domain simultaneously, whose center frequency will shift linearly with the variations of environment. The experimental results exhibit high linearity and interrogation ability for both the all-FP multiplexing system and hybrid multiplexing system. A strain interrogation sensitivity of 0.938 kHz/µɛ and temperature sensitivity of -0.699 MHz/°C have been realized, corresponding to a FP cavity length demodulation sensitivity of 1.563 MHz/µm. Furthermore, numerical studies about the impacts of the HCF-FP spectrum envelope on the RF response passband, as well as the theoretical minimum detectable cavity length and multiplexing capacity of the system, are also carried out.

Research into a novel surface acoustic wave sensor signal-processing system based on compressive sensing and an observed-signal augmentation method based on secondary information prediction

Due to their unique advantages, surface acoustic wave (SAW) sensors have attracted various disciplines to carry out thorough research. However, in their wireless applications, their high carrier frequency, low signal-to-noise ratio, and short effective signal length have led to poor signal measurement accuracy and complex detection systems. Using an SAW torque sensor as its objective, this paper describes the proposal and completion of a novel processing system based on compressive sensing (CS). The system was implemented using an analog-to-information conversion module. The module hardware’s structural parameters and signal recovery parameters were designed and optimized by simulation. Furthermore, an intervening interpolation method based on support vector machine (SVM) signal secondary information prediction was developed to achieve an effective extension of the observed signal. The method’s parameters and the SVM super parameters were optimized by a cuckoo search algorithm. The success rate of the predicted signal secondary information reached more than 94%. The compression ratio of the system reached 5.77‰ while ensuring successful signal frequency recovery. Finally, a torque static calibration experiment was carried out using the system prototype; the results show that the system sensitivity is 1.951 kHz Nm−1, which proves that the scheme and methods are effective. The SAW signal-processing system based on CS combines the advantages of traditional demodulation system solutions with low hardware costs, low data volume, and high interference immunity. This system will prompt some new thoughts about SAW sensor signal detection.

1.4‐mJ High Energy Terahertz Radiation from Lithium Niobates

AbstractFree‐space super‐strong terahertz (THz) electromagnetic fields offer multifaceted capabilities for reaching extreme nonlinear THz optics. However, the lack of powerful solid‐state THz sources with single pulse energy >1 mJ is impeding the proliferation of extreme THz applications. The fundamental challenge lies in hard to achieve high efficiency due to high intensity pumping caused crystal damage, linear absorption, and nonlinear distortion induced short effective interaction length, and so on. Here, through cryogenically cooling the crystals, tailoring the pump laser spectra, chirping the pump pulses, and magnifying the laser energies, 1.4‐mJ THz pulses are successfully realized in lithium niobates under the excitation of 214‐mJ femtosecond laser pulses via tilted pulse front technique. The 800 nm‐to‐THz energy conversion efficiency reaches 0.7%, and a free‐space THz peak electric and magnetic field reaches 6.3 MV cm−1 and 2.1 Tesla. Numerical simulations reproduce the experimental optimization processes. To show the capability of this super‐strong THz source, nonlinear absorption in high conductive silicon induced by strong THz electric field is demonstrated. Such a high‐energy THz source with a relatively low peak frequency is very appropriate not only for electron acceleration toward table‐top X‐ray sources but also for extreme THz science and nonlinear applications.

Efficient mixing enhancement by orthogonal injection of shear-thinning fluids in a micro serpentine channel at low Reynolds numbers

Viscoelastic fluids have been recently proposed to promote mixing effect in microfluidic systems, where limited success has been obtained. However, the flow and mixing mechanism of a viscoelastic fluid is still poorly understood, particularly regarding the roles of injection on mixing at low Reynolds numbers. In this work, an efficient mixer by orthogonal injection into a primary flow is proposed. The mixing behaviors of shear-thinning fluids in a serpentine channel with an orthogonal injection are investigated experimentally. Dye visualization and concomitant statistical analysis are conducted to quantitatively characterize the mixing performance and to reveal the flow kinematics. Enhanced mixing is achieved just over a short effective mixing length. The probability distribution functions (PDFs) analysis shows that the mixing efficiency, defined by the normalized concentration of dye intensity (Gan et al., 2007), can be significantly improved from 22% for the Newtonian fluids to 69% and 76% by using a shear-thinning fluid with polymer concentrations of 25 and 50 ppm, respectively. The decay exponents of shear-thinning fluids plateau at −3.4 indicates the occurrence of elastic instability. The relative-change-ratio fluctuations illustrates that the observation area can generate sufficient elastic stress to induce flow instabilities, resulting in effective mixing in the channel.

Performance and plume characteristics of an 85 W class Hall thruster

An 85 W class Hall thruster with inner and outer electromagnetic coils was developed, and its thrust performance and plume characteristics were experimentally evaluated. The 85-W Hall thruster required a maximum magnetic flux density along the channel centerline above 24.3 mT to achieve stable and efficient operation above a discharge voltage of 225 V. A specific impulse of 1050 s, thrust-to-power ratio of 59.5 mN/kW, and anode efficiency of 0.306 were achieved at a discharge voltage of 225 V and a discharge power of 88.9 W under a background pressure of 7.9 × 10−4 Pa. Moreover, the thruster achieved throttling at a discharge power of 47.6–118.5 W with stable operation. The low anode efficiency of the 85-W Hall thruster was due to low propellant utilization and a large beam divergence. The short effective length for the propellant ionization owing to the narrow channel is deduced to be the cause for the low anode efficiency in low-power Hall thrusters. The mass utilization efficiency of the 85-W Hall thruster improved as the anode mass flow density increased. Therefore, an increase in the anode mass flow density is required to improve the performance of the 85-W Hall thruster.

Carbon-Bridged Oligo(phenylene vinylene)s: A de Novo Designed, Flat, Rigid, and Stable π-Conjugated System.

The modern history of conducting organic systems started with a fortuitous error in 1967 on acetylene polymerization, followed by a rational discovery in 1976 on the effects of doping that generates a polaron and, hence, dramatically increases conductivity. Not unexpectedly, however, the prototypical polyacetylene suffers many problems, including C-C single bond rotation, short effective conjugation length, radiationless deactivation, and instability of the polarons. Several strategies have been put in place to solve these problems. An early approach relied on partial rigidification of the polyene structure by conversion into polymers with thiophene, pyrrole, and benzene linkages. An oligo(phenylene vinylene) (OPV) is an all-carbon analogue of polyacetylene, where every other diene unit in the polyene chain is converted to a benzene unit, still leaving many C-C single bonds freely rotating in the molecule. We considered adding additional carbon bridges to rigidify the OPV skeleton entirely to create a carbon-bridged OPV (COPV). Making such a compound was an obvious challenge. This Account describes the authors' efforts to design and synthesize a series of COPV molecules, where the benzene rings in OPV are bridged by sp3 carbon atoms to form a bicyclo[3.3.0]octatriene framework bearing a tetrasubstituted olefin at the ring fusion. This olefinic bond is so strained that it resists further deformation or conversion to sp3 centers, and hence, it is chemically stable despite the strain. The sp3 carbon bridges can bear organic side chains that hinder intermolecular interactions, rendering the excited states stable and long-lived even in the solid state. They also increase solubility, a common problem among rigid molecular systems. With these structural features, the COPV molecules were found to be well behaved both at a single-molecule level and as a bulk material. We reported in 2009 a method for the synthesis of COPVs and have, since then, reported their structures and physicochemical properties, including basic photophysical properties of neutral and charged derivatives, thermal and photostability, and fast electron transfer. These properties have rendered the COPV molecules useful for electronic and photonic research, for example, lasers, solar cells, and molecular wire applications. Noteworthy discoveries in the area connecting chemistry and physics include inelastic tunneling and long-range resonance tunneling at ambient temperature, which were previously observed only for organic molecular wires placed under cryogenic conditions. Given the ready availability of the COPV skeleton bearing a wide variety of substituents, this class of molecules will serve as versatile building blocks for fundamental and applied research on physicochemical and materials chemistry.

$\pi$ -Phase-Shifted Fiber Bragg Grating for Strain Measurement With High Spatial Resolution

Because the static strain measured by a uniform fiber Bragg grating is a mean value along the grating length, it is difficult to precisely measure a local strain when encountering nonuniformity. It is found that phase-shifted fiber Bragg gratings have short effective grating length and reflectivity approaching one at the central peak; these properties are beneficial for improving the spatial resolution. These advantages have been validated by calculating the light power distribution along the grating and by spectrum simulation using the transfer-matrix method integrated with finite element simulation. An interrogation system integrated with a newly designed algorithm has been used to automatically track the wavelength shift in the central peak. A set of comparison experiments that mimicked symmetrically parabolic strain and linearly increasing strain were conducted to demonstrate the advantage of the phase-shifted fiber Bragg grating over the conventional fiber Bragg grating in static measurements.

Evaluation of the effective length of passing lanes on two-lane highways

ABSTRACTThis study presents an investigation into effective length of passing lanes on rural two-lane highways using field and simulation data. Field data from two study sites in Oregon were used to calibrate and validate the traffic simulation program used in this study. The calibrated simulation model was then used in evaluating the effective length of passing lane under different traffic levels and percent no-passing zones. Study results showed that the effective length of a passing lane is a function of traffic level as well as the percent no-passing zones for any segment of two-lane highway. Further, results confirmed that the operational benefits of passing lanes generally last for a significant distance downstream of the passing lane, with this distance varying in the range between 3 and 20 miles depending on traffic level and percent no-passing zones. Expectedly, higher traffic levels and higher percentage of no-passing zones were found to result in shorter effective lengths.

Regenerated Fiber Bragg Grating Sensing System for Ultrasonic Detection in a 900 °C Environment

Heat-resistant composites, such as ceramic matrix composites and heat-resistant carbon fiber reinforced plastics (CFRPs), are expected to be used for aircraft engine parts. The development of reliable heat-resistant composite materials requires the use of nondestructive test techniques for evaluating the progression of damage during material testing at elevated temperatures. Furthermore, structural health monitoring (SHM) technologies that operate under harsh environments are expected to be realized for monitoring heat-resistant composite structures. To provide potential solutions for the establishment of such technologies, this research developed a heat-resistant ultrasonic sensor based on a regenerated fiber-optic Bragg grating (RFBG). First, we fabricated an RFBG by annealing a normal fiber-optic Bragg gratings (FBG) sensor. Because the RFBG exhibits high heat resistance at temperatures of 1000 °C, the sensor achieved stable ultrasonic detection at an elevated temperature. In addition, we attempted to use a π-phase-shifted FBG (PSFBG) as the seed grating to construct an ultrasonic sensor with enhanced performance. As a result, the regenerated phase-shifted fiber-optic Bragg grating (R(PS)FBG) sensor possessed a very short effective gauge length and achieved a broad frequency response to ultrasonic waves with frequencies greater than 1.5 MHz. The broadband detectability enables the R(PS)FBG sensor to acquire an accurate response to ultrasonic waves. Hence, we believe the regenerated Bragg grating-based ultrasonic sensors can contribute to establishing an effective nondestructive evaluation method for composite materials, thereby enabling a structural health monitoring system for a composite-made structure operating under extreme high-temperature environments.

高温で計測可能な光ファイバ超音波センサの構築

Because of the stable material property of optical fiber up to 1000℃, fiber-optic Bragg grating (FBG) sensor is considered as one of possible ultrasonic sensors used at ultrahigh temperature. However, disappearance of reflectivity of a normal FBG in the high temperature above 900℃ makes the ultrasonic detection impossible. In order to detect ultrasonic wave under high temperature environments, we conducted an anneal heat treatment to produce a regenerated fiber Bragg grating (RFBG) sensor. Because the RFBG has a stable reflectivity even at temperature of 1000℃, we detected the ultrasonic wave successfully at the temperature. Especially, because a π-phase-shifted FBG (PSFBG) was used as the seed grating, the RFBG sensor possessed very short effective gauge length that resulted in a broad bandwidth response to ultrasonic wave over 1 MHz. Hence, we believe that the ultrasonic RFBG sensors could be potentially applied for ultrasonic detection in non-destructive tests to evaluate microscopic damage in materials under extreme high-temperature environment.

A novel hybrid artificial photosynthesis system using MoS2 embedded in carbon nanofibers as electron relay and hydrogen evolution catalyst

Inspired by photosynthesis in nature, artificial photosynthesis (AP) systems have been widely investigated in the context of energy and environmental research. Here we report a noble-metal-free AP system for visible-light-driven H2 generation from aqueous solutions consisting of fluorescein (FL) as photosensitizer, single-layer ultrasmall MoS2 nanoplates embedded in carbon nanofibers (CNF) as electron relay and redox catalyst, and triethanolamine (TEOA) as sacrificial electron donor. This CNF–MoS2/FL system exhibits outstanding H2 evolution performance, with an H2 generation rate that exceeds not only both MoS2/FL (by 100%) and CNF/FL (by 1100%), but also the Pt/FL system (by 40%). The excellent photocatalytic activity of this CNF–MoS2/FL system can be ascribed to the synergistic effects of CNF and MoS2 coupling: (1) the simultaneous presence of MoS2 with its delocalized and increased Mo 4d unoccupied states and of CNF with increased graphitic characteristics enables electron transfer from FL∗ to MoS2 via CNF electron relay; (2) the single-layered ultrasmall MoS2 nanoplates with short effective lengths for electron transfer and high density of reactive S-edges effectively catalyze the H2 evolution reaction (HER). The presented work successfully fabricated a highly efficient AP system for solar H2 production from a fully aqueous solution and indicated CNF–MoS2 as a promising candidate to replace Pt for solar fuel conversion.

Surface-Sensitive Spectro-electrochemistry Using Ultrafast 2D ATR IR Spectroscopy

A new method is presented for the combination of spectro-electrochemistry and femtosecond 2D IR spectroscopy. The key concept is based on ultrathin (∼nm) conductive layers of noble metals and indium–tin oxide (ITO) as working electrodes on a single-reflection attenuated total reflectance (ATR) element in conjunction with ultrafast, multidimensional ATR spectroscopy. The ATR geometry offers prominent benefits in ultrafast spectro-electrochemistry, that is, surface sensitivity for studying electrochemical processes directly at the solvent–electrode interface as well as the application of strongly IR-absorbing solvents such as water due to a very short effective path length of the evanescent wave at the interface. We present a balanced comparison between usable electrode materials regarding their performance in the ultrafast ATR setup. The electrochemical performance is demonstrated by vibrational Stark-shift spectroscopy of carbon monoxide (CO) adsorbed to platinum-coated, ultrathin ITO electrodes. We furth...

Intermediate Megavoltage Photon Beams for Improved Lung Cancer Treatments

The goal of this study is to evaluate the effects of intermediate megavoltage (3-MV) photon beams on SBRT lung cancer treatments. To start with, a 3-MV virtual beam was commissioned on a commercial treatment planning system based on Monte Carlo simulations. Three optimized plans (6-MV, 3-MV and dual energy of 3- and 6-MV) were generated for 31 lung cancer patients with identical beam configuration and optimization constraints for each patient. Dosimetric metrics were evaluated and compared among the three plans. Overall, planned dose conformity was comparable among three plans for all 31 patients. For 21 thin patients with average short effective path length (< 10 cm), the 3-MV plans showed better target coverage and homogeneity with dose spillage index R50% = 4.68±0.83 and homogeneity index = 1.26±0.06, as compared to 4.95±1.01 and 1.31±0.08 in the 6-MV plans (p < 0.001). Correspondingly, the average/maximum reductions of lung volumes receiving 20 Gy (V20Gy), 5 Gy (V5Gy), and mean lung dose (MLD) were 7%/20%, 9%/30% and 5%/10%, respectively in the 3-MV plans (p < 0.05). The doses to 5% volumes of the cord, esophagus, trachea and heart were reduced by 9.0%, 10.6%, 11.4% and 7.4%, respectively (p < 0.05). For 10 thick patients, dual energy plans can bring dosimetric benefits with comparable target coverage, integral dose and reduced dose to the critical structures, as compared to the 6-MV plans. In conclusion, our study indicated that 3-MV photon beams have potential dosimetric benefits in treating lung tumors in terms of improved tumor coverage and reduced doses to the adjacent critical structures, in comparison to 6-MV photon beams. Intermediate megavoltage photon beams (< 6-MV) may be considered and added into current treatment approaches to reduce the adjacent normal tissue doses while maintaining sufficient tumor dose coverage in lung cancer radiotherapy.

Tailoring color emissions from N-doped graphene quantum dots for bioimaging applications

Unlike inorganic quantum dots, fluorescent graphene quantum dots (GQDs) display excitation-dependent multiple color emission. In this study, we report N-doped GQDs (N-GQDs) with tailored single color emission by tuning π-conjugation degree, which is comparable to the inorganic quantum dot. Starting from citric acid and diethylenetriamine, as prepared N-GQDs display blue, green, and yellow light emission by changing the reaction solvent from water, dimethylformamide (DMF), and solvent free. The X-ray photoelectron spectroscopy, ultraviolet-visible spectra results clearly show the N-GQDs with blue emission (N-GQDs-B) have relatively short effective conjugation length and more carboxyl group because H2O is a polar protic solvent, which tends to donate proton to the reagent to depress the H2O elimination reaction. On the other hand, the polar aprotic solvent (DMF) cannot donate hydrogen, the elimination of H2O is promoted and more nitrogen units enter GQD framework. With the increase of effective π-conjugation length and N content, the emission band of N-GQDS red-shifts to green and yellow. We also demonstrate that N-GQDs could be a potential great biomarker for fluorescent bioimaging. Nitrogen-doped graphene quantum dots emitting blue, green, or yellow light are promising biomarkers for fluorescence bioimaging. Dan Qu and colleagues in China tailored the emission color of the quantum dots by changing the reaction solvent used in their fabrication. Dots prepared from protic solvent-emitted blue (450 nm) light, those prepared with aprotic solvent emitted green (550 nm), and solvent-free dots emitted yellow (580 nm). The emission colors were pure and narrow band with full-width half-maximum values of 71, 86, and 111 nm and decay lifetimes of 14, 13, and 10 ns, respectively. Imaging experiments with a confocal fluorescence microscope and A549 cells labeled with the graphene dots demonstrated that the cells did indeed become brightly illuminated with visible colors when optically excited, suggesting that the graphene dots are suitable for bioimaging.

Study on differences between high contrast grating reflectors for TM and TE polarizations and their impact on VCSEL designs.

A theoretical study of differences in broadband high-index-contrast grating (HCG) reflectors for TM and TE polarizations is presented, covering various grating parameters and properties of HCGs. It is shown that the HCG reflectors for TM polarization (TM HCG reflectors) have much thicker grating thicknesses and smaller grating periods than the TE HCG reflectors. This difference is found to originate from the different boundary conditions met for the electric field of each polarization. Due to this difference, the TM HCG reflectors have much shorter evanescent extension of HCG modes into low-refractive-index media surrounding the HCG. This enables to achieve a very short effective cavity length for VC-SELs, which is essential for ultrahigh speed VCSELs and MEMS-tunable VCSELs. The obtained understandings on polarization dependences will be able to serve as important design guidelines for various HCG-based devices.