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In proton therapy, a highly conformal proton dose can be delivered to the tumor by means of the steep distal dose penumbra at the end of the beam range. The proton beam range, however, is highly sensitive to range uncertainty, which makes accurately locating the proton range in the patient difficult. In-vivo range verification is a method to manage range uncertainty, one of the promising techniques being prompt gamma imaging (PGI). In earlier studies, we proposed gamma electron vertex imaging (GEVI), and constructed a proof-of-principle system. The system successfully demonstrated the GEVI imaging principle for therapeutic proton pencil beams without scanning, but showed some limitations under clinical conditions, particularly for pencil beam scanning proton therapy. In the present study, we upgraded the GEVI system in several aspects and tested the performance improvements such as for range-shift verification in the context of line scanning proton treatment. Specifically, the system showed better performance in obtaining accurate prompt gamma (PG) distributions in the clinical environment. Furthermore, high shift-detection sensitivity and accuracy were shown under various range-shift conditions using line scanning proton beams.

A slow-wave structure named coupled double folded waveguide (CDFW) is proposed for traveling wave tube operating at terahertz region. Its electromagnetic characteristics and beam-wave interactions are presented in this paper. This structure, evolved from a single folded double ridge groove waveguide (DRGW) by intersecting the groove along its transverse direction, can operate at high-order TM20 resulting in increased horizontal dimension. Furthermore, this novel CDFW can interact with two pencil beams and have high beam-wave coupling impedance, which is beneficial to output high power at terahertz band. The proposed CDFW, when applying a dynamic velocity taper technique, can produce an output power of 210 W at 340 GHz with a 3-dB bandwidth of 13 GHz, and it is 80 W higher than a folded DRGW with a single beam at the same condition, when the beam voltage and beam current are 27.98 keV and 0.25 A, respectively.

This paper presents the results of the analysis of acoustic emission signals (AE) recorded during the propagation of sound waves in rock samples. The sources are excited by breaking a 3-mm-thick pencil lead (Hsu-Nielsen) on the surface of the rock samples at different AE source locations. Ten repetitions of pencil lead fracturing were performed at a given location. A VS150-M piezoelectric sensor with a frequency range of 100–450 kHz was attached to the upper surface of the rock samples. The results showed that the AE energy and the average frequency of the acoustic emission signals in the rock samples decreased with increasing distance from the AE source locations. These results can be used to establish a relationship between the characteristics of the acoustic emission signals and different rock types at different AE source locations.

Novel technological solutions for the design of positron emission tomography (PET) systems to be used in the in-beam beam-on monitoring of proton tracks within biological tissues represent the frontier of the instrumentation in proton therapy. We report a novel all-digital PET dual heads prototype based on the multivoltage threshold (MVT) technology, able to operate in beam-on modality. We demonstrate in phantom and animal experiments that, by using an event selection based on the energy of singles and on the delay with respect to the radio-frequency period of the proton beam bunches, the monitoring PET system is able to image the induced activity by both pristine and pencil proton beam with energy ranging between 70 and 150 MeV during irradiation.

PURPOSE Proton pencil beam energy spectrum is an essential parameter for calculations of dose and linear energy transfer. We extract the energy spectrum from measured integral depth dose (IDD). METHODS A measured IDD (measIDD) in water is decomposed into many IDDs of mono-energetic pencil beams (monoIDDs) in water. A simultaneous iterative technique is used to do the decomposition that extracts the energy spectrum of protons from the measIDD. The monoIDDs are generated by our analytic random walk model-based proton dose calculation algorithm. The linear independence of the monoIDDs is considered and high spatial resolution monoIDDs are used to improve their linear independence. To validate the extraction, first we use synthesized IDDs (synIDD) with Gaussian energy spectrum and compare the extracted energy spectrum with the Gaussian; second, for the energy spectrum extracted from measIDDs, the accuracy of the extraction is validated by comparing the calculated IDD from the energy spectrum with the measIDD. The measIDDs are derived from commissioning of a cyclotron proton pencil beam system with a Bragg peak ionization chamber. The nominal energy of the pencil beams is from 70 to 245 MeV. The monoIDDs are generated for energies from 0.05 to 275 MeV in steps of 0.05 MeV with a spatial resolution of 1 mm. RESULTS The difference of the extracted and original Gaussian energy spectrum peaked at 75 and 80 MeV was

In this work, we, for the first time, propose a quartz crystal microbalance (QCM) humidity sensor that is prepared by a one-step method based on pencil drawing. The scanning electron microscopy (SEM), atomic force microscope (AFM), and Raman spectra confirm some graphite flakes, and a layer of sensing film is formed, demonstrating the successful preparation of the QCM sensor. A series of experiments were performed by means of oscillating circuit and impedance analysis at room temperature. The impedance analysis method demonstrates that the QCM humidity sensor exhibits an excellent stability with a quality factor ( ${Q}$ ) that only drops from 47 923 to 43 849 in the whole humidity range, which is better than ever reported QCM humidity sensors. In addition, the sensor shows a good long-term stability with a maximal frequency deviation of less than 5% in a long-term test. Furthermore, the sensor displays a rapid response time ~8s and a recovery time less than 5 s. The underlying reasons for these excellent properties of the proposed sensor are analyzed and discussed. This research demonstrates that the pencil-drawn method is a simple, green, and cost-effective way for constructing a QCM humidity sensor with high performance.

In this article, design of a high-order-mode (TE20-mode) staggered double vane (SDV) traveling wave tube amplifier (TWTA) with two pencil electron beams is presented. Since, the dimensions are larger when compared to fundamental mode TWTAs, the high-power capacity can be achieved. Meanwhile, several ways to suppress the fundamental mode competition and improve the stability of our high-order-mode TWTA are studied thoroughly, such as limiting the gain of each stage and using metal or wave-absorbing material columns. A three-stage TE20-mode SDV TWTA with aluminum nitride column at the center of vanes is simulated to get an over 145-W peak power with a corresponding gain of 32.5 dB. The frequency spectrum is pure at 220 GHz and the output signal is a stable TE20-mode signal. The bandwidth reaches about 38 GHz. The results show that high-order-mode operation can develop the high-power capacity vacuum electron devices at terahertz band.

Frequency diversity array (FDA) has been widely studied due to its nature of range-angle-dependent. However, the basic FDA generates an S-shaped range-angle coupled beampattern, which limits its application in target detection and localization. Recently, the FDA with sinusoidal frequency offset (Sin-FDA) has been proposed, which provides a narrow pencil beampattern, but at the cost of high sidelobes. In this letter, the FDA with modified sinusoidal frequency offset (MSin-FDA) is proposed. In MSin-FDA, the frequency offset of Msin-FDA can be flexibly adjusted by introducing extra configuration parameters. In addition, we use genetic algorithm to optimize the configuration parameters so as to obtain an enhanced beampattern. Simulation results demonstrate that, compared with the existing FDA schemes with nonuniform frequency offset, the proposed method has better spatial focusing, sidelobe suppression, and array resolution performance under the same total frequency offset.

This letter proposes a unit integrating reflectarray and transmitarray functions together. The proposed units can form multifunctional metasurface (MS), which can realize both focusing (with required focus points and point numbers) and multiple pencil beams (with required direction, and beam numbers) based on x - and y -polarizations, respectively. The developed MS has the following advantages: low sidelobe, high focusing efficiency, high aperture efficiency, multibeam, dual-band and less layer number. The MSs formed by the units have multifunctional applications, such as multibeam communication splitter, and point to point or point to multipoint in near field communication and wireless and power transmission.

PURPOSE In vivo range and dose verification based on proton-induced acoustics (protoacoustics) is potentially a useful tool for proton therapy. Built upon our previous study with two-dimensional reconstruction, the time reversal (TR) method was extended to three-dimensional (3D) and evaluated at two treatment sites (head and liver) through simulation, with the emphasis on a number of aspects such as increased spatial coverage, computational workload, and signal interference among slices. METHODS Two mono-energetic pencil beams were modeled in each site. The k-Wave toolbox was used to investigate the propagation and TR reconstruction of acoustic waves. The performance was quantitatively assessed based on mean square error (MSE) for dose verification and Bragg peak localization error (ΔBP ) for range verification, with regard to five parameters: number of sensors, sampling duration, sampling timestep, spill time, and noise level. RESULTS The respective impacts of five parameters are examined. Under the optimum setting, the achievable ΔBP can be limited within 1 voxel (voxel size: 3 × 3 × 3 mm3 ) and the achievable MSE can be limited below 0.02, for the head case (56 sensors) and the liver case (204 sensors), respectively. CONCLUSIONS The feasibility of range and dose verification utilizing the 3D TR method is demonstrated, as the very first step. In spite of several challenges unique to the 3D case (spatial coverage, computational workload, and signal interference among slices, etc.), promising performance is found and can be further improved through optimizing the deployment of sensors. The proposed approach may find potential use in several applications: beam diagnostics, in vivo dosimetry, and treatment monitoring.

The purpose of this study was to determine the types, proportions, and energies of secondary particle interactions in a Compton camera (CC) during the delivery of clinical proton beams. The delivery of clinical proton pencil beams ranging from 70 to 200 MeV incident on a water phantom was simulated using Geant4 software (version 10.4). The simulation included a CC similar to the configuration of a Polaris J3 CC designed to image prompt gammas (PGs) emitted during proton beam irradiation for the purpose of in vivo range verification. The interaction positions and energies of secondary particles in each CC detector module were scored. For a 150-MeV proton beam, a total of 156 688(575) secondary particles per 108 protons, primarily composed of gamma rays (46.31%), neutrons (41.37%), and electrons (8.88%), were found to reach the camera modules, and 79.37% of these particles interacted with the modules. Strategies for using CCs for proton range verification should include methods of reducing the large neutron backgrounds and low-energy non-PG radiation. The proportions of interaction types by module from this study may provide information useful for background suppression.

Nanowires of porous MnO2 were directionally decorated on graphenized pencil lead and used as a fiber coating for selectively analysis of the 15 pesticides by headspace solid-phase microextraction (...

Herein, we introduce a low-cost and straightforward method for preparing pH sensors based on parchment-type paper and pencil traces as a base and electrode, respectively. The hydrophobic feature of the parchment paper supports the relatively long life of the proposed pH sensor. The results indicate that the present sensors have a Nernstian response with a Nernstian slope of 52.1 ± 1.5 mV/pH and a good linearity of 0.995 from pH 4 to 10. The stability of the proposed electrode is approximately 0.75 mV/h. The prepared electrodes show a relatively long operating life compared with the published results of ordinary paper-based pH devices. However, the Nernstian factor decreases over time and stabilizes at approximately 28 mV/pH after two months. This approach provides a low-cost and reproducible pH sensor.

Purpose Patient‐Specific Quality Assurance (PSQA) measurement analysis depends on generating metrics representative of calculation and measurement agreement. Considering the heightened capability of discrete spot scanning protons to modulate individual dose voxels, a dose plane comparison approach that maintained all of the capabilities of the well‐established γ test, but that also provided a more intuitive error parameterization, was desired. Methods Analysis was performed for 300 dose planes compared by searching all calculated points within a fixed radius around each measured pixel to determine the dose deviation. Dose plane agreement is reported as the dose difference minimum (DDM) within an empirically established search radius: ΔDmin(r). This per‐pixel metric is aggregated into a histogram binned by dose deviation. Search‐radius criteria were based on a weighted‐beamlet 3σ spatial deviation from imaging isocenter. Equipment setup error was mitigated during analysis using tracked image registration, ensuring beamlet deviations to be the dominant source of spatial error. The percentage of comparison points with

Purpose The interplay effect between dynamic pencil proton beams and motion of the lung tumor presents a challenge in treating lung cancer patients in pencil beam scanning (PBS) proton therapy. The main purpose of the current study was to investigate the interplay effect on the volumetric repainting lung plans with beam delivery in alternating order (“down” and “up” directions), and explore the number of volumetric repaintings needed to achieve acceptable lung cancer PBS proton plan. Method The current retrospective study included ten lung cancer patients. The total dose prescription to the clinical target volume (CTV) was 70 Gy(RBE) with a fractional dose of 2 Gy(RBE). All treatment plans were robustly optimized on all ten phases in the 4DCT data set. The Monte Carlo algorithm was used for the 4D robust optimization, as well as for the final dose calculation. The interplay effect was evaluated for both the nominal (i.e., without repainting) as well as volumetric repainting plans. The interplay evaluation was carried out for each of the ten different phases as the starting phases. Several dosimetric metrics were included to evaluate the worst‐case scenario (WCS) and bandwidth based on the results obtained from treatment delivery starting in ten different breathing phases. Results The number of repaintings needed to meet the criteria 1 (CR1) of target coverage (D95% ≥ 98% and D99% ≥ 97%) ranged from 2 to 10. The number of repaintings needed to meet the CR1 of maximum dose (ΔD1%

This study aims to measure the environmental costs (eco-cost) and the eco-efficiency ratio rate (EER) of the production of pencils and formulate some recommendations to improve the manufacture sustainability. The measurement of Eco-efficiency was performed using life cycle assessment (LCA) with the eco-cost method. The pencil manufacturer produces a waste of 20 %, and the product rejects 37 %. The material used is wood, slat, and chemical material for painting. The result of the data processing shows that the eco-costs of IDR 50.593.583 for 4200 grosses production lot size. The eco-efficiency index or EEI for pencil product was 1,69, which means that the products are affordable and sustainable. The eco-efficiency ratio rate (EER) is 41% means that pencil production processes need improvement. The single score Impact Category Diagram shows that the most significant environment impact category is climate change. The recommendation to improve the EER of pencil production based on Impact Category Diagram is (1) to increase the utilizing of wood waste and (2) to increase the capability of technicians and operators to reduce the product rejection. These recommendations aim to reduce the wood consumed in production.

International audience; The present work demonstrates that the pencil glide mechanism is a physically reliable and a computationally efficient model to simulate the nonlinear behaviour of b.c.c. single and polycrystals. For that purpose, the pencil glide extension of Schmid's criterion used by Gilormini [1] is incorporated in a single crystal model and in a homogenized polycrystal model accounting for large elastoviscoplastic deformations. The response of the pencil glide model in terms of stress-strain curves and lattice rotation is compared to the prediction based on the consideration of all ({110}〈111〉 + {112}〈111〉) slip systems. In the case of α-iron single crystals both approaches are shown to accurately reproduce recent experimental results [2, 3]. The comparison is extended to α-iron polycrystals behaviour under tension, compression, rolling and simple shear loading conditions. The evolution of crystallographic textures obtained either based on pencil glide or using the 24 slip systems is analyzed and compared to classical experimental results from the literature. Limitations of the approach, especially in the case of simple shear textures, are also pointed out. The pencil glide approach can be viewed as a reduced order model enhancing computational efficiency of crystal plasticity simulations involving many slip mechanisms.

A novel lab-in-a-pencil graphite microfluidic sensing electrode (μFSE) was fabricated for real-time flow injection measurement of the antipsychotic drug clozapine (Clz). A simple, low-cost, and reusable μFSE was obtained by using 3D printing of a microfluidic chamber integrated with a flat pencil graphite without the need to utilize complex technologies. The μFSE has tubular geometry with 800 μm diameter, where the solution continuously flows in the holes of flat pencil graphite electrodes. Under optimized conditions, this device offers fast and effective Clz detection with good analytical features. A linear calibration curve in the range of 0.5 to 10 μM Clz was obtained with good sensitivity (0.01275 μA μM-1) and detection limit (24 nM). Finally, we demonstrate the applicability of our lab-fabricated microfluidic electrochemical device by monitoring Clz in serum samples at low concentrations.

Exploring a robust, extremely sensitive, cost-effective and reliable assay platform for the precise analysis of dopamine (DA) has become a big challenge predominantly at the clinical level. To participate in this quest, herein, we fabricated a perylene diimide (PDI) self-assembled graphitic surface of the graphitic pencil electrode (GPE) anchored copper oxide (CuO). The self-assembled N-rich PDI led to the fast movement of ions by decreasing the bandgap and improved the electron transport kinetics with more exposed catalytic active sites, thus resulting in the robust electrochemical sensing of DA. The designed sensor exhibited good sensitivity (4 μM

Herein, a portable 3-D printed miniaturized bipolar electrode-electrochemiluminescence (BPE-ECL) platform is presented. The platform has a smartphone-enabled read-out method for ECL signal analysis, a 9-V Hi-watt battery for power supply, and graphitized mesoporous carbon/multiwalled carbon nanotube (GMC/MWCNT) nanomaterial-modified pencil graphite electrodes (PGEs) as bipolar and driving electrodes. The nanomaterial-modified pencil graphite bipolar electrode (PG-BPE) showed great electrocatalytic activity toward luminol–H2O2 and luminol–O2 ECL reactions in neutral medium. The sensitized luminol–O2 and luminol–H2O2 reactions were successfully applied for sensing of H2O2, O2, and CO2. With optimized parameters, the determination of H2O2, O2 and CO2 can be in the linear range of 0.08– $5000~\mu \text{M}$ , 0.3–9 mg/L, and 0.6–9 mg/L with the detection limit of $0.069~\mu \text{M}$ , 0.15 mg/L, and 0.45 mg/L. As a prototype application, quantitative detection of glucose has been carried out with a modified PGE anchored with GOx (GMC/MWCNT at GOx). The prepared electrode was analyzed for physicochemical and microscopic characterizations. The modified PGE showed an excellent ability to detect the glucose in a linear range of $1~\mu \text{M}$ –10 mM with a detection limit of $0.31~\mu \text{M}$ . Finally, the platform was subjected to real sample analysis of H2O2 in clinical H2O2, cosmetic bleach, O2, and CO2 in lake water and tap water and glucose in human blood serum samples. The results indicated that the proposed platform offered excellent reliability, accuracy, and amenable to be used for multiple point-of-care biochemical analysis.

Commercially available high quality 9B pencil graphite was used for sensing of trace concentrations of nitrogen dioxide (NO2) and ammonia (NH3) at sub-ppm levels in air at ambient temperature and pressure. The pencil graphite was characterized using scanning electron microscopy (SEM), Raman spectroscopy and powder X-ray diffraction (XRD) techniques. In comparison to other sensing materials pencil graphite is very well recognized owing to its cheaper price, simplicity of fabrication, abundant over-the-counter obtainability and easy modification. The principal of operation of the chemiresistive gas sensor is based on the variation in the electrical resistance due to the selective interaction between the pencil graphite network and the specific gaseous analyte in a two-pole format. The degree of change in electrical resistance of the pencil graphite network depends on the concentration of the gaseous analyte to which it is exposed. On the basis of this fact qualitative as well as quantitative detection of the gaseous analytes can be achieved. The sensing limits of 100 parts-per-billion (ppb) and 500 ppb with sensor response times of ∼30 s and ∼50 s for NO2 and NH3, respectively is recorded using our gas detector, and are found significantly efficient in comparison to the NO2 and NH3 detectors available commercially in market.

Purpose Proton minibeam radiation therapy, a spatial fractionation concept, widens the therapeutic window. By reducing normal tissue toxicities, it allows a temporally fractionated regime with high daily doses. However, an array shift between daily fractions can affect the tissue-sparing effect by decreasing the total peak-to-valley dose ratio. Therefore, combining temporal fractions with spatial fractionation raises questions about the impact of daily applied dose modulations, reirradiation accuracies, and total dose modulations. Methods and Materials Healthy mouse ear pinnae were irradiated with 4 daily fractions of 30 Gy mean dose, applying proton pencil minibeams (pMB) of Gaussian σ = 222 μm in 3 different schemes: a 16 pMB array with a center-to-center distance of 1.8 mm irradiated the same position in all sessions (FS1) or was shifted by 0.9 mm to never hit the previously irradiated tissue in each session (FS2), or a 64 pMB array with a center-to-center distance of 0.9 mm irradiated the same position in all sessions (FS3), resulting in the same total dose distribution as FS2. Reirradiation positioning and its accuracy were obtained from image guidance using the unique vessel structure of ears. Acute toxicities (swelling, erythema, and desquamation) were evaluated for 153 days after the first fraction. Late toxicities (fibrous tissue, inflammation) were analyzed on day 153. Results Reirradiation of highly dose-modulated arrays at a positioning accuracy of 110 ± 52 μm induced the least severe acute and late toxicities. A shift of the same array in FS2 led to significantly inducted acute toxicities, a higher otitis score, and a slight increase in fibrous tissue. FS3 led to the strongest increase in acute and late toxicities. Conclusions The highest normal-tissue sparing is achieved after accurate reirradiation of a highly dose modulated pMB array, although high positioning accuracies are challenging in a clinical environment. Nevertheless, the same integral dose applied in highly dose-modulated fractions is superior to low daily dose-modulated fractions.

The design features of a multichannel pad (position-sensitive) ionization-chamber camera (PC) based on a warm liquid are considered. The PC is intended for joint operation with a TV-type detector (DTeT) in simulation of dose fields in a water phantom in the mode of a scanning (modulated) pencil proton beam. The electronic section of the PC has been tested with a pulsed X-ray source. As a detector, the PC measures the absolute value of the dose released in a specified target voxel by the pencil proton beam in a single pulse.

In present study, a low-cost and steady electrochemical biosensor has been developed based on graphene oxide nanoparticles (GONPs), electrodeposited on the pencil lead electrode (PLE). The physical and morphological studies revealed the nano-scale range of GONPs that has an average grain size/layer thickness of 2.27 nm and agglomeration size of 90-120 nm. Urease enzyme was immobilized on PLE/GONPs electrode after surface treatment with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) to impart stable peptide bond. Scanning electron microscopy (SEM) studies demonstrate the difference between unmodified and modified PLE electrodes and depict the spherical, circular and flaky-like morphology. The electrochemical analysis of urea considerably improved on the PLE/GONPs/Ur compared to the untailored PLE electrode. The reported urea biosensor operated in a linear dynamic range between 0.30-50 mM that attained a recognition limit of 0.06 mM and exhibited an advanced exposure sensitivity of 0.814 μA mM-1 cm-2.

The article describes the proposed new multifunctional ionization chamber (MIC) designed to measure dose profiles when the medical accelerator "Prometheus" is operating in the scanning "pencil beam" mode. A digital image acquisition detector (DIDE) with a tissue-equivalent water phantom is used to calibrate the accelerator before a radiation therapy session. The application of the CPPI on the beam of a proton accelerator operating in the mode of beam splitting into spots with a scanning beam is considered. The CDPI detector allows for a few accelerator pulses in on-line mode to see how the energy release of each spot is distributed over the area of the irradiated target, which is the actual calibration of the accelerator before the proton therapy session. During the proton therapy session, it is planned to install the MIC directly in front of the patient. The MIC chamber contains two ionization chambers operating simultaneously — a pad chamber (PC) operating on gas or "warm liquid" and a strip ionization chamber operating only on gas (SC). At the accelerator "Prometheus" it is proposed to use a MIC, which will be used in the mode of operation by the method of active scanning with a "pencil" proton beam. The use of the MIC operation is intended to control the density of the beam intensity during the irradiation of the "target" in the patient during the proton therapy session. In case of violation of the planned operating mode of the accelerator and the beam goes beyond the parameters preset before the session, the deviation detection control system (SDMS) will turn off the accelerator. The device of the readout electronics (SE) of the MIC and SKOO cameras is described. This proposed detector, including the MIC and SKOO camera and the reading electronics serving it, will improve the quality of the therapeutic beam supply, due to the accurate determination of the absorbed dose density supplied by the scanning beam to each spot of the irradiated target, and therefore the generated high dose distribution field will correspond to the irradiated volume of the patient and will increase the safety and control of patient exposure to the target. The PC included in the MIC is designed on a "warm liquid" (or gas) and is a high-precision ionization chamber with coordinate sensitivity over the width of the irradiated target. The SC included in the MIC operates on gas and controls the direction of the incident beam to a given spot in the target. A version of the charge-sensitive preamplifier (QCD) and the SE system designed for experimental verification of the MIC prototype has been developed. The SCOO circuit working in conjunction with the MIC camera allows you to control the predetermined parameters of the irradiation of the patient's target boundaries and turns off the accelerator if these parameters deviate from the initially specified ones.

The documentary history of Olmsted, Jr’s search for a patent (number 1,070,284) unfolds in Job File 2919 of the Olmsted Associates records, housed at the Library of Congress and accessible digitall...

This paper presents a study on the synthesis of a position-phase optimized reconfigurable linear array antenna with uniform amplitude distributions. The objective is to produce a pencil/flat-top beam pair. In this position-phase method, a pencil beam is duly generated with zero degree phases and phases are varied between −180° and 180° to produce a flat-top beam keeping position of the elements and amplitude excitations common to both pencil and flat-top beams. The amplitude distribution of the elements is kept uniform. The phases as well as position of the elements are optimized by Teaching Learning Based Optimization (TLBO), modified Quantum Particle Swarm Optimization (QPSO) and Symbiotic Organisms Search (SOS) algorithms to produce the beam pair. The simulations are done for two Sets of elements and a null placement is included in one of the Sets. The results obtained using these algorithms are duly compared with each other and it is found that SOS algorithm performed in par with TLBO algorithm in the generation of the radiation pattern parameters and better over TLBO and QPSO in statistical values.

The aim of this work was to study the effect of proton pencil beam scanning in the Bragg peak in the dose range of 0.1-1.5 Gy on the induction of cytogenetic damage in the bone marrow, reactive oxygen species (ROS) production in whole blood, and the state of lymphoid organs after total body irradiation of mice. Irradiation was carried out in the Prometeus proton synchrotron (Protvino) in the Bragg peak with proton energy at the output of 90-116 MeV. It was found that, under irradiation of mice in the range of low and medium doses of proton pencil beam scanning in the Bragg peak, the relative biological effectiveness (RBE) according to the criterion of cytogenetic changes was 1.15. In addition, it was found that the pathophysiological effect on the lymphoid organs and the production of ROS by blood cells were different as compared with the effect of X-rays.

A simple, centrifugeless vortex-assisted ionic liquid-based dispersive liquid-liquid micro-extraction method was developed for spectrofluorometric determination of Rhodamine B dye. Analytical extraction parameters including pH, type and amount of ionic liquid, salt concentration, vortex rate and time were examined and optimized. Matrix effects of potentially interfering ions and dyes were investigated and their tolerable concentrations were determined by applying optimum conditions. Detection limit and preconcentration factor were determined 0.01 μg L-1 and 30, respectively. Dynamic range of the method was linear at RhB concentration range between 0.025 and 1000 μg L-1. Relative standard deviations were 3.9% for the ten replicates measurements of 0.125 μg L-1 Rhodamine B. The method was successfully applied to different samples including anti-freezes, liquid soap, matches, red pencil core and lipsticks. RhB concentrations of liquid and solid samples were determined between 2.05 μg mL-1 and 10.05 μg mL-1 and 307 μg g-1 and 2.75 mg g-1, respectively.

2D and 3D beam synthesis from different antenna array arrangements are investigated in this paper. Planar sunflower, conformal cylinderical and spherical helical array arrangements are studied. The particle swarm optimization (PSO) technique is used to predict the phase distribution on the array elements. The beam synthesis is achieved by comparing the array factor with a predetermined mask with both upper and lower limits according to the intented application requirements. Different 2D and 3D masks are used in beam synthesis as pencil, flat-top, and cosecant single beam are predicted. The planar sunflower antenna array is investigated due to its high gain, low side-lobe level (SLL) below − 20 dB and its compact size. The phase distribution of sunflower array is estimated using PSO to radiate dual-beams in different planes. Dual-beam with pencil, flat-top, and cosecant beams are obtained with different half-power beam widths. 3D conformal antenna arrays of cylindrical and spherical helical arrangements are studied. Each 3D conformal array consists of four arms shifted in position by 90° orintation angle. Each arm is designed to radiate single beam in a specific direction. Four-beams are considered to radiate in the directions of θ1,2,3,4 = 30°, and ϕ1 = 0°, ϕ2 = 90°, ϕ3 = 180°, and ϕ4 = 270° with SLL optimized below − 17 dB. The array arrangements analysis is based on the array theory formulation, through the implemention of the estimiated equation using a home programmed MATLAB code.

The electrochemical preparation of nanostructured polymeric network consisted of poly(o-phenylenediamine)-multi-walled carbon nanotube (PoPD-MWCNT) on a disposable and commonly used pencil graphite electrode (PGE) was demonstrated. The obtained PoPD-MWCNT/PGE electrode was prepared via one-step electropolymerization using cyclic voltammetry (CV) and characterized by CV and electrochemical impedance spectroscopy (EIS). Surfaces topographies of the electrodes were investigated with scanning electron microscopy (SEM) in order to differentiate electrode modifications. The modified electrode highly improved the electrochemical properties of the PoPD/PGE and PGE. The fabrication process of the modified electrode was reproducible with a relative standard deviation of 3.8% (n = 3). Afterwards, sensitive detection of mitomycin C was performed based on the interaction of double-stranded DNA (dsDNA) immobilized on PoPD-MWCNT/PGE with mitomycin C. Thus, a detailed investigation of the interaction of dsDNA immobilized PoPD-MWCNT/PGEs with mitomycin C were also evaluated at various interaction intervals from 0 to 30 min in an efficient process. This promising electrode provided a linear concentration range for mitomycin C from 0.5 mg L−1 to 25 mg L−1 with a low limit of detection, 0.012 mg L−1, and a limit of quantification, 0.039 mg L−1, based on the guanine oxidation peaks using differential pulse voltammetry (DPV) (n = 3). The recoveries were also determined in spiked serum and satisfactory results emphasized the use of the electrode for clinical applications.

The objective of this study is to determine X-ray dose distribution and the correlation between central, peripheral and weighted-centre peripheral doses for various phantom sizes and tube voltages in computed tomography (CT). We used phantoms developed in-house, with various water-equivalent diameters (Dw) from 8.5 up to 42.1 cm. The phantoms have one hole in the centre and four holes at the periphery. By using these five holes, it is possible to measure the size-specific central dose (Ds,c), peripheral dose (Ds,p), and weighted dose (Ds,w).The phantoms are scanned using a CT scanner (Siemens Somatom Definition AS), with the tube voltage varied from 80 up to 140 kVps. The doses are measured using a pencil ionization chamber (Ray safe X2 CT Sensor) in every hole for all phantoms. The relationships between Ds,c, Ds,p, and Ds,w, and the water-equivalent diameter are established. The size-conversion factors are calculated. Comparisons between Ds,c, Ds,p, and Ds,ware also established. We observe that the dose is relatively homogeneous over the phantom for water-equivalent diameters of 12-14 cm. For water-equivalent diameters less than 12 cm, the dose in the centre is higher than at the periphery, whereas for water-equivalent diameters greater than 14 cm, the dose at the centre is lower than that at the periphery. We also find that the distribution of the doses is influenced by the tube voltage. These dose distributions may be useful for calculating organ doses for specific patients using their CT images in future clinical practice.

A study was performed to utilize Pencil Lead Drawn Paper Sensor (PLDPS) as a strain and damage sensor by drawing multiply Pencil Sensors on two paper types. To evaluate the optimal paper as a PLDPS substrate of two type papers, i.e., plain and Han papers were used. The stability and uniformity of the mechanical properties, were compared for the paper types. Variability of electrical resistivity (ER) was also determined using four different types of pencil lead to make the PLDPS. In the evaluation of the properties of the PLDPS, for the different pencil lead types, the pencil lead weight was determined by drawing multiple lines and the ER of neat pencil leads and PLDPS compared. Interfacial properties of the PLDPS with different pencil lead types were measured by a spreading test, which provides information on wetting and permeability properties, using double distilled water. The sensitivity and uniformity of the pencil lead paper sensors made of four different pencil leads were compared in tensile loading. Plain paper was more suitable than Han Paper for use as the substrate of PLDPS. In addition, compared to other pencil leads, 6B, which exhibited low sensitivity but high uniformity, was determined to be the most suitable pencil lead.

This paper describes a new type of sensor that can monitor electrical signals for external stress or damage and heat transfer. It is composed of conductive pencil lead graphite, which is sensitive, affordable and easy-to-handle. This work was to detect mechanical damages in composites using Pencil Lead Drawn Paper Sensor (PLDPS). To measure electrical resistance (ER) via bending, by narrowing the distance between glass plates attached with PLDPD, ER increased stepwise while ER decreased with widening the distance reversely. The PLDPS can easily change the shape in a rectangular vortex. ER change responded well in tensile and flexural tests, while it showed leveling off under cyclic compression. Two-dimensional ER mapping was used during impact, drilling and heat transfer tests for detecting damage and thermal transfer. Compared to strain gauges, PLDPS can be applied inexpensively to detect damages successfully under various mechanical tests.

The paper focuses on the problem of electromagnetic wave propagation in plane shielded dielectric waveguide. The waveguide is characterized by an isotropic inhomogeneous permittivity and constant permeability. We study symmetric guided waves that characterised by a pair of (coupled) propagation constants. Using an operator pencil approach, we prove a discreteness property for the searched-for propagation constants.

Made available in DSpace on 2020-12-12T02:41:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-06-01 The real-time monitoring of manufacturing processes is essential to achieve high-quality standards and uniformity at reduced costs. The monitoring of machining processes is usually performed by acoustic emission sensors, which measure the dynamic waves of mechanical stress that propagate through the material during the grinding process. This work studies the application of knock sensors, commonly used in the monitoring of combustion engines, as a low-cost and high-robustness alternative to acoustic emission sensors in the monitoring of the grinding process. Built to operate mechanically attached to the engine block, the knock sensor is resistant to high temperatures, liquids, and particles. In order to demonstrate the feasibility of the sensor, different tests were performed. By determining its resonant frequency, it was possible to identify the response curve of the sensor and its optimal operating range. The acoustic impulse test, generated by the pencil lead break technique, allowed the comparative analysis of the spectral performance between the acoustic emission sensor and the knock sensor. The performance of the knock sensor in an industrial environment was also verified in a case study. The results showed a similar spectral behavior between both sensors when subjected to the same stimulus, demonstrating the feasibility of using the knock sensor to monitor the grinding process. School of Engineering University Center of Lins (UNILINS) Electrical Engineering Department School of Engineering São Paulo State University (UNESP) Electrical Engineering Department School of Engineering São Paulo State University (UNESP)

Purpose Most clinical computed tomography (CT) protocols use helical scanning; however, the traditional method for CTDIvol measurement replaces the helical protocol with an axial scan, which is not easily accomplished on many scanners and may lead to unmatched collimation settings and bowtie filters. This study assesses whether CTDIvol can be accurately measured with a helical scan and determines the impact of pitch, collimation width, and excess scan length. Methods CTDIvol was measured for 95 helical protocols on 31 CT scanners from all major manufacturers. CTDIvol was measured axially, then again helically, with the scan range set to the active area of the pencil chamber seen on the localizer image. CTDIvol measurements using each method were compared to each other and to the scanner-displayed CTDIvol . To test the impact of scan length, the study was repeated on four scanners, with the scan range set to the phantom borders seen on the localizer. Results It was not possible to match the collimation width between the axial and helical modes for 12 of the 95 protocols tested. For helical and axial protocols with matched collimation, the difference between the two methods averaged below 1 mGy with a correlation of R2 = 0.99. The difference between the methods was not statistically significant (P = 0.81). The traditional method produced four measurements that differed from the displayed CTDIvol by >20%; no helical measurements did. The accuracy of the helical CTDIvol was independent of protocol pitch (R2 = 0.0) or collimation (R2 = 0.0). Extending the scan range to the phantom borders increased the measured CTDIvol by 2.1%-9.7%. Conclusion There was excellent agreement between the two measurement methods and to the displayed CTDIvol , without protocol or vendor dependence. The helical CTDIvol measurement can be accomplished more easily than the axial method on many scanners and is reasonable to use for QC purposes.

We report a solution-phase method for the fabrication of Pd-Ag nanorods featuring an asymmetric, pencil-like structure with a sharpened Ag tip at one end and a Pd decahedron at the other end. The f...

PURPOSE In this study, we investigated computationally and experimentally a hexagonal-pattern array of spatially fractionated proton minibeams produced by proton pencil beam scanning (PBS) technique. Spatial fractionation of dose delivery with millimeter or submillimeter beam size has proven to be a promising approach to significantly increase the normal tissue tolerance. Our goals are to obtain an optimized minibeam design and to show that it is feasible to implement the optimized minibeams at the existing proton clinics. METHODS An optimized minibeam arrangement is one that would produce high peak-to-valley dose ratios (PVDRs) in normal tissues and a PVDR approaching unity at the Bragg peak. Using Monte Carlo (MC) code TOPAS we simulated proton pencil beams that mimic those available at the existing proton therapy facilities and obtained a hexagonal-pattern array of minibeams by collimating the proton pencil beams through the 1-3 mm diameter pinholes of a collimator. We optimized the minibeam design by considering different combinations of parameters including collimator material and thickness (t), center-to-center (c-t-c) distance, and beam size. The optimized minibeam design was then evaluated for normal tissue sparing against the uniform pencil beam scanning (PBS) by calculating the therapeutic advantage (TA) in terms of cell survival fraction. Verification measurements using radiochromic films were performed at the Emory proton therapy center (EPTC). RESULTS Optimized hexagonal-pattern minibeams having PVDRs of >10 at phantom surface and of >3 at depths up to 6 cm were achieved with 2 mm diameter modulated proton minibeams (with proton energies between 120 and 140 MeV) corresponding to a spread-out-Bragg-peak (SOBP) over the depth of 10-14 cm. The results of the film measurements agree with the MC results within 10%. The TA of the 2 mm minibeams against the uniform PBS is >3 from phantom surface to the depth of 5 cm and then smoothly drops to ~1.5 as it approaches the proximal edge of the SOBP. For 2 mm minibeams and 6 mm c-t-c distance, we delivered 1.72 Gy at SOBP for 7.2 × 7.2 × 4 cm3 volume in 48 s. CONCLUSIONS We conclude that it is feasible to implement the optimized hexagonal-pattern 2 mm proton minibeam radiotherapy at the existing proton clinics, because desirable PVDRs and TAs are achievable and the treatment time is reasonable.

Highlights • Heterogeneous lung tissue causes degradation of pristine proton pencil beams. • A degradation model was implemented into a treatment planning system. • For large tumor volumes, degradation was negligible. • The mean lung dose was not negatively affected in any of the investigated cases. • Small tumor volumes surrounded by lung tissue might get a local target underdose., Background and purpose Proton therapy may be promising for treating non-small-cell lung cancer due to lower doses to the lung and heart, as compared to photon therapy. A reported challenge is degradation, i.e., a smoothing of the depth-dose distribution due to heterogeneous lung tissue. For pencil beams, this causes a distal falloff widening and a peak-to-plateau ratio decrease, not considered in clinical treatment planning systems. Materials and methods We present a degradation model implemented into an analytical dose calculation, fully integrated into a treatment planning workflow. Degradation effects were investigated on target dose, distal dose falloffs, and mean lung dose for ten patient cases with varying anatomical characteristics. Results For patients with pronounced range straggling (in our study large tumors, or lesions close to the mediastinum), degradation effects were restricted to a maximum decrease in target coverage (D95 of the planning target volume) of 1.4%. The median broadening of the distal 80–20% dose falloffs was 0.5 mm at the maximum. For small target volumes deep inside lung tissue, however, the target underdose increased considerably by up to 26%. The mean lung dose was not negatively affected by degradation in any of the investigated cases. Conclusion For most cases, dose degradation due to heterogeneous lung tissue did not yield critical organ at risk overdosing or overall target underdosing. However, for small and deep-seated tumors which can only be reached by penetrating lung tissue, we have seen substantial local underdose, which deserves further investigation, also considering other prevalent sources of uncertainty.