Standard Reference Conditions Research Articles

Amendment to JIS Z 8126-1 Vacuum Technology –Vocabulary– Part 1 : General Terms

JIS Z 8126-1 Vacuum technology –Vocabulary– Part 1 : General terms, which corresponds to ISO 3529-1 Vacuum technology –Vocabulary– Part 1 : General terms, was amended for the first time in 22 years in 2021 to harmonize with the amendment of ISO 3529-1 in 2019. The committee for the amendment of JIS Z 8126-1, which was mainly composed of members of joint committee for standardization of JVSS and JVIA, worked to prepare the amended draft. Several important amended points such as the definition of “standard reference condition”, “low pressure”, “high pressure” and so on are introduced.

A Simple Index of Lake Ecosystem Health Based on Species-Area Models of Macrobenthos

An effective biological index should meet two criteria: (1) the selected parameters have clear relationships with ecosystem health and can be measured simply by standard methods and (2) reference conditions can be defined objectively and simply. Species richness is a widely used estimate of ecosystem condition, although it is increased by nutrient enrichment, a common disturbance. Based on macrobenthos data from 91 shallow Yangtze lakes disconnected from the mainstem, we constructed an observed species (SO)-area (A) model to predict expected species richness (SE), and then developed an observed to expected index (O/E-SA) by calculating the SO/SE ratio. We then compared O/E-SA with three other commonly used indices regarding their ability to discriminate cultivated and urban lakes: (1) River Invertebrate Prediction and Classification System (RIVPACS; O/E-RF), (2) Benthic Index of Biotic Integrity (B-IBI), and (3) Average Score Per Taxon (ASPT). O/E-SA showed significant positive linear relationships with O/E-RF, B-IBI and ASPT. Quantile regressions showed that O/E-SA and O/E-RF had hump-shape relationships with most eutrophication metrics, whereas B-IBI and ASPT had no obvious relationships. Only O/E-SA, O/E50 and B-IBI significantly discriminated cultivated from urban lakes. O/E-SA had comparable or higher performance with O/E-RF, B-IBI and ASPT, but was much simpler. Therefore, O/E-SA is a simple and reliable index for lake ecosystem health bioassessment. Finally, a framework was proposed for integrated biological assessment of Yangtze-disconnected lakes.

P67 - kQ,Q0 for cyberknife from the assessment of TPR20,10 = f(PDD20,10) in standard reference conditions

P67 - kQ,Q0 for cyberknife from the assessment of TPR20,10 = f(PDD20,10) in standard reference conditions

Effect of the Mexico City's air density in low-energy X-ray spectra and its influence in the air kerma and absorbed depth-dose to water

Mexico City is situated at around 2,200 m relative to the sea-level, so the use of computed X-ray spectra or measured from other laboratories might affect the air-kerma or the absorbed-dose. This work aims at investigating the effect of the air-density in Mexico City on the air-kerma and the absorbed-depth-dose to water using low-energy X-ray spectra. Air-kerma was calculated for both standard reference (SRC) and laboratory conditions (LC) using unfiltered X-ray spectra of 20 kV, 50 kV, 100 kV and 120 kV measured at PTB. Absorbed depth-dose measurements in water were performed for the same beam-qualities using an ionization-chamber. Independently, depth-dose has been calculated through Monte-Carlo (MC) DOSRZnrc. X-ray spectra from SpekCalc were also generated and used to calculate the absorbed-depth-dose for comparison. For the air-kerma, differences up to 7% were found between the LC and SRC. For the absorbed-depth-dose, the experimental results agree quite well (0.3%–0.7%) with MC for kilovoltages over 50 kV. For 20 kV, the experimental depth-dose curve decreases smoother than the calculated one showing a difference of 25%–50% depending on the depth, which is possibly associated to the output of the X-ray tube. Comparing the absorbed-depth-dose curves between LC and SRC, discrepancies of more than 50% are observed at 20 kV. Concerning the data from SpekCalc, disagreements are observed for all the energies studied. The air-density affects mainly the air-kerma and the absorbed-depth-dose at energies below 50 kV. Based on this work, one can suggest the use of unfiltered X-ray spectra published by PTB and corrected under LC to calculate the absorbed-dose using MC.

Evaluation and clinical implementation of in vivo dosimetry for kV radiotherapy using radiochromic film and micro-silica bead thermoluminescent detectors

PurposekV radiotherapy treatment calculations are based on flat, homogenous, full-scatter reference conditions. However, clinical treatments often include surface irregularities and inhomogeneities, causing uncertainty. Therefore, confirmation of actual delivered doses in vivo is valuable. The current study evaluates, and implements, radiochromic film and micro silica bead TLD for in vivo kV dosimetry. MethodsThe kV energy and dose response of EBT3 film and silica bead TLD was established and uncertainty budgets determined. In vivo dosimetry measurements were made for a consecutive series of 30 patients using the two dosimetry systems. ResultsEnergy dependent calibration factors were required for both dosimetry systems. The standard uncertainty estimate for in vivo measurement with film was 1.7% and for beads was 1.5%. The mean measured dose was −2.1% for film and −2.6% for beads compared to prescription. Deviations up to −9% were found in cases of large surface irregularity, or with underlying air cavities or bone. Dose shielding by beads could be clinically relevant at low kV energies and superficial depths. ConclusionsBoth film and beads may be used to provide in vivo verification of delivered doses in kV radiotherapy, particularly for complex situations that are not well represented by standard reference condition calculations.

Prediction of I-V characteristics for a PV panel by combining single diode model and explicit analytical model

Manufacturers of photovoltaic panels typically only provide electrical parameters under standard reference condition (SRC) that is not sufficient to determine their overall performance. It is important for designers to find a flexible and reliable method to model and accurately predict I-V characteristics under varying operating conditions. This paper proposes a method to predict the I-V characteristics of a PV panel under varying operating conditions by combining the single diode model and explicit analytical model. The method takes temperature and solar irradiance as inputs and produces I-V characteristics under any operating condition as outputs, including the maximum power point, fill-factor, and entire I-V curve. Considering the aging effect, the parameters under the measured reference condition (MRC) are used for calculation instead of the manufacturer data at SRC where the process is as follows: (1) the shape parameters in the explicit analytical model were calculated from measurements at MRC; (2) the physical parameters in the single diode model were identified from the measured data at MRC and used for the prediction; (3) the physical parameters under any operating condition were calculated based on the dependence of the physical parameters on the temperature and solar irradiance; (4) the I-V characteristics were described and analyzed using the explicit analytical model because of its simplicity and explicit expression. Outdoor experiments were performed to validate the proposed method. Our calculated results show reasonable agreement with the experimental results.

Determination of kQ using MLC-collimated rectangular fields for absolute dosimetry of the CyberKnife.

Traditional CyberKnife (CK) calibration uses TG‐51, which requires kQ to be defined using the standard reference condition of 100 cm SSD in a 10 cm×10 cm field. Since the CK is calibrated using a 6 cm fixed‐aperture collimating cone at 80 cm SAD, the BJR‐25 method is commonly used to relate circular‐field PDDs to square‐field PDDs for kQ determination. Using the InCise MLC system, the CK is able to deliver rectangular fields, allowing a more direct measurement of %dd(10 cm) using conventional reference conditions. We define the PDD correction factor (CPDD) as the ratio of %dd(10 cm) measured using CK reference conditions to that measured using standard TG‐51 reference conditions. Using four ionization chambers (A1SL, CC08, CC13, and A19), %dd(10 cm) is measured using a 6 cm fixed cone at 80 cm SSD and at 100 cm SSD using an effective 10 cm×10 cm MLC‐collimated field. These values are used to calculate CPDD, while the latter is used to directly calculate a kQ value. This direct kQ value is then compared to values determined using the BJR‐25 method. Using the MLC system, this study demonstrates conversion between the %dd(10 cm) measured using CyberKnife reference conditions and TG‐51 reference conditions. These values provide the means for derivation of a kQ curve as a function of direct measurements of %dd(10 cm) using a 6 cm fixed‐aperture collimating cone at 80 cm SSD.PACS number: 87.55.Qr

Effects of environmental stress following myocardial infarction on behavioral measures and heart failure progression: The influence of isolated and group housing conditions

BackgroundHeart failure (HF) prognosis is negatively influenced by adverse environmental conditions associated with psychological distress and depression. The underlying mechanisms are not well understood because of insufficient experimental control in prior clinical and epidemiological studies. Using a validated animal model we examined whether distress-producing environmental manipulations (social isolation and crowding) increase HF progression following myocardial infarction (MI). MethodsMI was induced using coronary artery ligation in 8-week old male Wistar rats (N=52) and results were compared to sham surgery (N=24). Housing conditions were randomly assigned at 5days post MI or sham surgery (1/cage=isolation, 2/cage=standard reference condition, or 4/cage=crowding) and continued for 17weeks until the end of observation. The open field test was used to test behavioral responses. Echocardiograms were obtained at weeks 8 and 16, and left ventricular (LV) weight at week 17. ResultsHousing conditions increased behavioral markers of distress (p=0.046) with the strongest effects for the isolated (1/cage) (p=0.022). MI did not increase distress-related behaviors compared to sham. MI-surgery resulted in characteristic HF indices (left ventricular ejection fraction (LVEF) at week 16=46±12% vs. 80±7% in sham, p<0.001). Housing condition was not related to LVEF or LV weight (p>0.10). ConclusionsAdverse environmental conditions, particularly isolated housing, produce increases in some of the behavioral indicators of distress. No effects of housing were found on post-MI progression of HF. The distress–HF associations observed in humans may therefore reflect common underlying factors rather than an independent causal pathway. Stronger environmental challenges may be needed in future animal research examining distress as related HF progression.

Comments on “An efficient analytical approach for obtaining a five parameters model of photovoltaic modules using only reference data” (Appl. Energy 111 (2013) 894–903)

In the recent work entitled “An efficient analytical approach for obtaining a five parameters model of photovoltaic modules using only reference data” (Appl. Energy 111 (2013) 894–903), Lo Brano and Ciulla (2013) [1] proposed a set of five equations to be used in a resolution procedure for the identification of the five-parameter model of photovoltaic modules by starting from data available on datasheet at standard reference condition. Some comments about this work are discussed in the present letter to the editor.

Evaluation of neutron dose equivalent from the Mevion S250 proton accelerator: measurements and calculations

Neutron production is of concern for proton therapy, especially for passive scattering proton beam delivery methods. The levels of neutron dose equivalent vary significantly with system design and treatment parameters. The purpose of this study was to examine neutron dose equivalent per therapeutic dose (H/D) around the Mevion S250 proton therapy system, a novel design of proton therapy systems. The benchmark comparisons between measurement and simulation were found to be within a factor of 2 for most cases. The H/D values were evaluated as a function of various parameters. The results showed that, at a standard reference condition (10 × 10 cm2 field size, distance 1 m detector-to-isocenter lateral to the primary proton beam direction), the H/D values range from 0.72 to 3.37 mSv Gy−1 for all configurations studied. The H/D values generally (1) decreased as the neutron detectors moved away from the isocenter, (2) decreased with increasing aperture field sizes, (3) increased with increasing angle from the initial beam axis and (4) were independent of treatment nozzle position. The H/D trends were consistent with other existing passive scattering proton accelerators reported in the literature.

TH‐D‐BRCD‐02: TG‐51 Addendum ‐ Overview and Implementation

This presentation will describe the new addendum to the AAPM's TG‐51 protocol covering photon beam reference dosimetry, which is in the final stages of review and will be published in 2012. The addendum does not hange either the formalism of TG‐51 or the standard reference conditions (i.e., 10 cm × 10 cm field at 1 m) but provides new chamber‐specific data together with detailed guidance on the relevant factors to take into account when following the TG‐51 protocol. The presentation will review the addendum in some detail with particular focus on: 1) Best practice recommendations to minimize errors and ensure consistent dosimetric reporting, including choice of chamber, experimental procedures, determination of correction factors, and application to FFF linacs.2) An in‐depth discussion of uncertainties with guidance on how the clinical physicist can affect the overall uncertainty in the determination of absorbed dose to waterLearning Objectives:1. Understand the scope of the TG‐51 addendum or photon beam dosimetry.2. Understand how the addendum should be implemented to achieve the highest level of accuracy.3. Understand how to construct an uncertainty budget for the determination of dose at the reference point and how the clinical user can influence the overall value of uncertainty.

SU-E-T-15: Small and Nonstandard Photon Field Dosimetry Characterization Using Monte Carlo Methods.

To quantify uncertainty reduction in small photon field dosimetry through characterization of ionization chambers and calibration conditions using detailed Monte Carlo methods benchmarked against NIST-traceable measurements. Phase space profiles were obtained using detailed EGSnrc Monte Carlo models for a Varian 6 MV photon linear accelerator, and a NIST-traceable cobalt-60 teletherapy unit. The responses of a farmer-type ionization chamber, two micro-ionization chambers, and one scanning-type ionization chamber were simulated in multiple calibration conditions. Calibration conditions included static field sizes ranging from (10×10) cm squared to (0.5×0.5) cm squared for the 6 MV and cobalt-60 beam qualities and an additional dynamic IMRT plan for the 6 MV beam quality. Calibration conditions also consisted of ionization chambers placed in a standard water phantom and in a specially designed acrylic phantom. Tolerance limits on the calibration conditions were investigated. All models were benchmarked against measured beam quality data, including ionization chamber beam quality correction factors for the standard absorbed dose to water cobalt-60 calibration coefficient. The majority of the simulated small field response values fell within the uncertainty of the measured values. A database was created for several proposed small field calibration conditions to provide comparisons with the Co-60 standard reference conditions. The database includes the small field calibration conditions' beam quality correction factors, tolerances, and dose calibration uncertainties. The characterization of multiple calibration conditions provided an improved understanding of how the cobalt-60 ionization chamber absorbed dose to water calibration coefficient from an ADCL can optimally be applied to small and nonstandard field calibrations to reduce the associated dose uncertainty. The developed methodology will contribute to future research of other small field radiotherapy modalities. The resulting database provides support for future recommendations on the implementation of small and non-standard field calibration protocols.

TU-C-BRA-02: Calibrating the Output of a Linear Accelerator - TG-51 Updated

Although dosimetry protocols tend to be fairly long lived it is more than ten years since the AAPM's TG‐51 protocol was published. With the developments in the technology for dose delivery and advances in the measurement and calculation of ion chambercalibration coefficients it is reasonable to question the validity of TG‐51 for the determination of reference (absolute) dose in 2011. Four areas are immediately obvious: 1. The majority of chambers available today do not have kq factors listed in TG‐51. 2. Users can obtain linac‐based absorbed dose calibration coefficients for ion chambers from calibration laboratories on a routine basis. 3. Monte‐Carlo radiation transport algorithms now allow accurate modelling of ion chamber geometries. 4. Linacs with very different beam parameters (e.g., flattening‐filter‐free) are now being introduced into clinical practice. 5. In light of these issues the AAPM set up a working group to review TG‐51 and provide clarification. The group would focus on accelerators capable of reproducing standard reference conditions (i.e., 10 cm × 10 cm field at 1 m) and the output would be an addendum that updates the TG‐51 protocol to the situation in 2011. This presentation will deal primarily with megavoltage photon beams and will discuss the content of the proposed report: i) Calculated k Q factors for new chambers developed after the publication of TG‐51 ii) A comparison of these calculations with measured k Q factors obtained at primary standards laboratories worldwide. iii) An in‐depth discussion of uncertainties with guidance on how the clinical physicist can affect the overall uncertainty in absorbed dose to water iv) Best practice recommendations to minimize errors and ensure consistent dosimetric reporting In addition there will be some discussion of the issues to be faced in the update for electron beamdosimetry. Development of electron beam standards has lagged behind that for photon beams and further experimental and theoretical work is required before an update to the electron part of TG‐ 51 can be considered. Issues include: i) status of primary standards worldwide; ii) validity of a 60Co‐based calibration (direct versus cross‐ calibration); iii) choice of chamber, cylindrical or parallel‐plate; iv) correct values of kQ factors in light of recent determinations of chamber perturbation factors. Learning objective: 1. Rationale for an update to TG‐51 2. Content of photon beam addendum 3. Timeline and research requirements for electron beam update.

Comment on “Roles of donor and acceptor nanodomains in 6% efficient thermally annealed polymer photovoltaics” [Appl. Phys. Lett. 90, 163511 (2007)

In a recent letter, Kim et al. reported on a 6.1% efficient polymer photovoltaic cell. The reported 6.1% efficiency under standard reference conditions 25 °C, 1000 W m−2 total irradiance, IEC 60904 global reference spectrum is not consistent with the device’s reported quantum efficiency QE . The 6.1% claim comes from Fig. 3 for cell D2. The shortcircuit current density Jsc for this cell is not reported. However, digitizing the data in Fig. 3 yields a Jsc of 15.42±0.05 mA /cm2. Assuming the QE in Fig. 2 C at 297 K corresponds to the QE of cell D2, then this QE integrates to 8.40 mA /cm2 with a maximum QE of 61.8%. To make the QE in Fig. 2 C agree with the reported Jsc corresponding to the claimed 6.1% efficient cell, the maximum QE has to be 113%. This is not physically possible. Or conversely, the efficiency would have to be 3.3%. Claims that this is not the QE of cell D2 will have a relatively small effect, provided the wavelength range of the photoresponse is comparable. Since a well-calibrated reference cell was used and an attempt was made to estimate the spectral error, the mistake is probably in the device area—which is not unexpected for a device with an area less than 10 mm2. This implies substantial current or light collection outside the reported area.

Framework for the Rapid Optimization of Soluble Protein Expression in Escherichia coli Combining Microscale Experiments and Statistical Experimental Design

A major bottleneck in drug discovery is the production of soluble human recombinant protein in sufficient quantities for analysis. This problem is compounded by the complex relationship between protein yield and the large number of variables which affect it. Here, we describe a generic framework for the rapid identification and optimization of factors affecting soluble protein yield in microwell plate fermentations as a prelude to the predictive and reliable scaleup of optimized culture conditions. Recombinant expression of firefly luciferase in Escherichia coli was used as a model system. Two rounds of statistical design of experiments (DoE) were employed to first screen (D-optimal design) and then optimize (central composite face design) the yield of soluble protein. Biological variables from the initial screening experiments included medium type and growth and induction conditions. To provide insight into the impact of the engineering environment on cell growth and expression, plate geometry, shaking speed, and liquid fill volume were included as factors since these strongly influence oxygen transfer into the wells. Compared to standard reference conditions, both the screening and optimization designs gave up to 3-fold increases in the soluble protein yield, i.e., a 9-fold increase overall. In general the highest protein yields were obtained when cells were induced at a relatively low biomass concentration and then allowed to grow slowly up to a high final biomass concentration, >8 g.L-1. Consideration and analysis of the model results showed 6 of the original 10 variables to be important at the screening stage and 3 after optimization. The latter included the microwell plate shaking speeds pre- and postinduction, indicating the importance of oxygen transfer into the microwells and identifying this as a critical parameter for subsequent scale translation studies. The optimization process, also known as response surface methodology (RSM), predicted there to be a distinct optimum set of conditions for protein expression which could be verified experimentally. This work provides a generic approach to protein expression optimization in which both biological and engineering variables are investigated from the initial screening stage. The application of DoE reduces the total number of experiments needed to be performed, while experimentation at the microwell scale increases experimental throughput and reduces cost.

Fidelity of J1269 and J2452

Abstract This study compares data from the two Society of Automotive Engineers test methods for rolling resistance: J-2452 (Stepwise Coast-Down) and J-1269 (Equilibrium) steady state. The ability of the two methods to evaluate tires was examined by collecting data for 12 tires. The data were analyzed and the data showed that the two methods ranked the tires the same after the data were regressed and the rolling resistance magnitude was calculated at the Standard Reference Condition. In addition, analysis of the two methods using this matched set of testing provided an opportunity to evaluate each of these test standards against the other. It was observed that each test has merits absent from the other.

Modeled performance of polycrystalline thin‐film tandem solar cells

AbstractThe optimum bandgaps for two‐terminal monolithic multijunction devices have typically been studied under a fixed set of environmental conditions, using ideal device models. This study examines the effects of a realistic dark‐current for typical state‐of‐the‐art thin‐film polycrystalline cells on the optimum energy gap for a series‐connected two‐junction cell. The optimum energy gaps are compared for a series‐connected tandem cell under standard reference conditions and the energy produced for five different reference days where the temperature, spectral irradiance and total irradiance varied. The optimum bandgaps were found to be 1.72 ± 0.02 eV for the top cell and 1.14 ± 0.02 eV for the bottom cell. Published in 2002 by John Wiley &amp; Sons, Ltd.

DETECTING CUMULATIVE EFFECTS ON HEADWATER STREAMS IN THE ROUTT NATIONAL FOREST, COLORADO1

ABSTRACT: This study evaluated the use of a modified pebble count procedure (Bevenger and King, 1995) to detect cumulative watershed effects on headwater streams in the Routt National Forest in northcentral Colorado. The 42 sample reaches were stratified by disturbance (reference or disturbed) and geologic terrene (granitic or mixed sedimentary‐volcanic). Water surface slope was a significant control on the number of fine particles in the reference reaches in both terranes, and the data from the disturbed reaches were adjusted accordingly. The disturbed reaches in the granitic terrene generally had a higher percentage of fine particles, and the adjusted number of fine particles was significantly correlated with the number of road crossings. Disturbed reaches in the sedimentary‐volcanic (s‐v) terrane generally did not have significantly more fine particles, nor were the adjusted numbers of fine particles significantly correlated with any management index. The lack of significant trends in the s‐v streams is probably due to differences in weathering between the two rock types, and the location of the sample reach relative to sedimentary outcrops. Two other procedures were also used to assess cumulative watershed effects, with the Pfankuch channel stability rating yielding stronger and more consistent differences between the reference and the disturbed streams than the Tarzwell substrate ratio. We conclude that it may be difficult to define a standard reference condition, and that the number of road crossings is more strongly correlated with the number of fine particles than equivalent clearcut area.

Views considered at TAGSI-FSG and the Universities' National Proposal

The Fracture Sub-Group of the Nuclear Utilities Technical Advisory Group on Structural Integrity (TAGSI) has considered and published statements on both the 'Definition of Upper Shelf' and on 'Operation off the upper shelf' with particular reference to the nuclear industry. These statements are reviewed critically and the potential impact of constraint effects on these statements discussed. It is pointed out that current definitions of transition temperature behaviour are inevitably for standard reference conditions, since the transition is dependent on triaxiality and on strain rate, so that a single definition of transition temperature for all situations is a pious dream. The important effects of constraint and the distinction between transition temperature for initiation of fracture under static loading and that for continued cleavage fracture propagation at high strain rate is emphasised. Some recent work in the University sector on constraint effects including the author's own research group is described. An outline is also given of proposals for a major collaborative National Research Programme involving seven University Groups on the underlying problems of predicting fracture behaviour of full-scale structures in the transition temperature range, including a concerted effort on constraint effects.

In Situ AC Electrical Conductivity Measurement on Bi3FeMo2O12

AbstractThe dynamic evolution of the defect structure of the Bi3FeMo2O12 surface determined by processes frequently encountered in heterogeneous catalysis (e.g. heating‐cooling cycles, adsorption and/or reaction of reactive gases with solid surfaces) can be followed either by direct in situ measurement of the AC electrical conductance, or by comparing the electrical conductance data of successive experiments on the same sample, in standard reference conditions, after various in situ treatments.