Clear Polystyrene Research Articles

Influence of drinking cups of different materials on emotional and acceptance responses, and perception of sensory attributes of soft drinks

The aim of this study was to investigate whether drinking cups made of different materials (white polystyrene, crystal-clear polystyrene, paper, Styrofoam, and glass) can influence the response to soft drinks in terms of emotions, acceptance and perception in younger adult consumers. Experiments were conducted with three different groups of university students who (1) participated in the survey on expectations of disposable cups, (2) performed sensory tests on emotional and hedonic responses and (3) evaluated selected sensory characteristics of soft drinks served in the test cups. The characteristics of the cups influenced the overall acceptability of the soft drink, while the flavor acceptability and the perception of flavor intensity were not affected. Compared to the heavier cups, the soft drink served in lighter cups was perceived as more viscous. The soft drink was rated most acceptable when consumed from the glass and least acceptable when tasted from the Styrofoam. The Styrofoam, paper and white polystyrene had an impact on reducing the overall acceptability of the soft drink. The emotional map identified in the study for the consumption of soft drinks from different cups could be related to the sensory characteristics of the cups. Glass can be considered a more acceptable vessel for soft drink consumption compared to disposable cups, while crystal–clear polystyrene is more acceptable than paper, Styrofoam and white/opaque polystyrene. When selecting materials for disposable cups, preference should be given to materials that have similar properties to glass, such ashigher weight, low flexibility, low surface graininess and high translucency.

Virucidal Efficacy of Gaseous Ozone Against Type 1 Herpes Simplex Virus (HSV-1)

ABSTRACT Viruses represent a major threat to human health and are capable of spreading either via direct exposure or contamination of inanimate surfaces. Certain viruses have been shown to remain viable on surfaces of dental implants and devices, fabrics and on plastics for hours, days and weeks representing a source of continuous viral transmission which must be mitigated. In this study, we compared the effect of varying concentrations of gaseous ozone (40, 20, 10, 5, and 1 ppm) on Herpes Simplex Virus (HSV-1) coated on the surfaces of clear polystyrene tissue culture (TC) plates and stainless-steel disc at varying time intervals (1.5, 3, 6, and 8 h) at >90% relative humidity and at 21–25 ˙C (±2˙C). Test samples were placed at a height of 1 and 1.5 m from ozone source. Viral viability after ozone exposure was determined using Vero cells and the viral titer was quantified using the Spearman–Karber’s method. Overall, inactivation of HSV-1 was dependent on ozone concentration and the duration of exposure. At 20 and 40 ppm, ozone rapidly depleted virus viability after 6 h. At 5 and 10 ppm a time-dependent reduction in viral infectivity was observed. At 10 ppm, viral titer decreased from approximately 5.2 pfu/mL at T = 0 to 3.5 and 2.1 pfu/mL after 1.5- and 6-h exposure on plastic surfaces. Similarly, viral titer decreased from approximately 5.6 pfu/mL at T = 0 to 3.0 to 2.0 pfu/mL at same time frame on steel surfaces. This study builds on earlier research in the field and demonstrates the ability of gaseous ozone to inactivate HSV-1 on two surfaces commonly found in food, medical and dental settings. This study recommends that further work is completed to identify optimum ozone, humidity, and temperature combinations to inactivate such viruses on surfaces found within these environments.

Novel chip-based isoelectric focusing device for fractionation of bacteria prior to their mass spectrometry identification

We have developed a planar chip utilizing divergent geometry of separation channel capable of vertical free-flow electrophoresis of particles at flows of lower hundreds of microliters per minute. The divergent flow isoelectric focusing (DF-IEF) chip consists of two sheets of clear polystyrene glass which serve as a base with working channels and a top cover sealing the separation channel. Optimization showed that the chip is capable to form pH gradient within 1 h and separation is completed in 5 or more minutes depending on the sample volume. The vertical position of the chip enabled analysis of sedimenting particles including microorganisms. Four different common bacteria species inactivated with H2O2 vapors were analyzed in a series of experiments. Isoelectric points were determined with capillary isoelectric focusing with following fractionation using DF-IEF with intact cell matrix-assisted laser desorption/ionization mass spectrometry detection. The DF-IEF chip fractionation proved promising for bacterial sample preparation from complex matrices for subsequent identification of whole cells by mass spectrometry.

Making medical devices safer: impact of plastic and silicone oil on microbial biofilm formation

Medical devices face the challenge of microbial biofilm attached to the surface. Ultimately, this may jeopardize the function of the device and increase the patient's risk of infection. However, reliable methods to prevent biofilm are lacking. To investigate the effect of silicone oil-coated polypropylene plastic, used in a new automatic urinometer, on biofilm formation; furthermore, to explore the impact of silicone oil viscosity and compare polypropylene with polystyrene, another common medical plastic. Common pathogens, including extended-spectrum beta lactamase (ESBL) -producing and multi-drug-resistant bacteria, as well as Candida albicans, were investigated. Isogenic Escherichia coli strains deficient in the important biofilm forming factors curli, cellulose and type 1 fimbriae (fim D) were used to determine the possible mode of action by silicone oil. Clear flat-bottomed polypropylene or polystyrene wells were pretreated with either low- or medium-viscosity silicone oil and microbes were added. After 72 h, biofilm formation was quantified using crystal violet assay. Silicone oil-coated polypropylene plastic surfaces, regardless of the oil viscosity, significantly inhibited biofilm formation of all tested Gram-negative and Gram-positive bacteria, including ESBL-producing and multi-drug resistant strains, as well as C.albicans. Silicone oil did not affect bacterial or candida growth and curli fimbriae were found to be the main target of silicone oil. Polypropylene plastic itself without oil had a better effect in preventing biofilm formation than polystyrene. These findings suggest a new strategy to decrease microbial biofilm formation, which may reduce hospital-acquired infections and prevent dysfunction of medical devices.

New Generation of Large Scale Scintillation Counters for Detection of EAS and Use in Guard Systems of Experimental Physics Setups

The work is dedicated to the discussion of four new types of large-area scintillation counters design intended for detection of EAS and the use in the guard systems of experimental physics setups with low-cost production. The solid counters based on scintillating polystyrene plates are produced by melting clear polystyrene granules with additives in a mirror mold. Other counters are based on lentil-like polystyrene scintillation granules which are a new kind of plastic scintillators produced at IHEP. WLS fibers and SiPM as a photo sensor are used for a light detection. The dimensions of the tested detectors were 500 × 500 and to 1000 × 1000 mm2, their measured light output was up to 180 ph.e.

Effects of under-water cutting treatments on oleocellosis development, quality and shelf-life of minimally processed Persian lime fruit

The main problem for minimally processed acid limes commercialization is oleocellosis, a physiopathy generated on the surface of the fruit by the release of essential oils from flavedo’s oil glands due to processing, which causes sinking of the tissue, necrosis and loss of product quality. In order to reduce this problem, we evaluate the effect of underwater cutting (UWC), either alone or in combination with other chemicals treatments on the development of oleocellosis and quality of minimally processed Persian lime.Persian lime fruit was cut into 8 wedges inside a refrigerated chamber at 10 °C under water (UWC) at 4 °C (control) or UWC with calcium lactate (5%) and 4-hexylresorcinol (4HR, 1 mM), either alone or in combination. The obtained minimally processed Persian lime fruit were washed, disinfected and stored in crystal clear polystyrene clam shells at 7.5 °C for 10 d. Visual quality and physicochemical parameters were determined. UWC + calcium presented the lowest levels of dehydration, weight loss, lipid peroxidation and the minimum damage at the cutting surface, showing to be the best treatment for minimally processed Persian lime reaching 10 d of shelf life and retaining marketable quality.

The uptake of macroplastic & microplastic by demersal & pelagic fish in the Northeast Atlantic around Scotland

This study reports plastic ingestion in various fish found from coastal and offshore sites in Scottish marine waters. Coastal samples consisted of three demersal flatfish species (n=128) collected from the East and West coasts of Scotland. Offshore samples consisted of 5 pelagic species and 4 demersal species (n=84) collected from the Northeast Atlantic. From the coastal fish sampled, 47.7% of the gastrointestinal tracts contained macroplastic and microplastic. Of the 84 pelagic and demersal offshore fish, only 2 (2.4%) individuals from different species had ingested plastic identified as a clear polystyrene fibre and a black polyamide fibre. The average number of plastic items found per fish from all locations that had ingested plastic was 1.8 (±1.7) with polyamide (65.3%), polyethylene terephthalate (14.4%) and acrylic (14.4%) being the three most commonly found plastics. This study adds to the existing data on macroplastic and microplastic ingestion in fish species.

The targeting accuracy of a preclinical MRI-guided focused ultrasound system.

Assess the accuracy, precision, and sources of error using a preclinical MR-guided focused ultrasound system. A preclinical focused ultrasound system, described previously [Chopra et al., Med. Phys. 36(5), 1867-1874 (2009)], was tested on a benchtop and with 3T GE, 3T Philips, and 7 T Bruker MR scanners for spatial targeting accuracy and precision. Randomly distributed water-filled holes drilled into a polystyrene plate were imaged using MRI and targeted using treatment planning software. The ultrasound focus of a 72 mm, f-number 0.8, 1.16 MHz transducer was aimed at the target locations, and 1-2 s continuous-wave sonications were performed on clear polystyrene plates to create localized spots of melted plastic. The distance between target and observed locations was measured and analyzed. Retrospective analysis of targeting accuracy was performed on preclinical data obtained from other experiments at their institution using the same system. The results suggest that the sources of targeting error under MR guidance can be roughly separated into three components--normally distributed random error; constant shift from inaccuracy in detection of the initial ultrasound focus; and angular misalignment between MR and focused ultrasound (FUS) coordinates. The lower bound on the targeting error was estimated to be 0.25 ± 0.13 mm, while the maximum observed targeting error did not exceed 2 mm. Measures required to reduce errors and improve targeting were developed to reduce the registration and misalignment errors such that maximum error was reduced to 0.36 ± 0.14 mm. Retrospective in vivo analysis indicated that the error was 1.02 ± 0.43 mm, including error extrinsic to the system. The FUS system, as described, is capable of precise and accurate sonications. The largest source of error--misregistration of the coordinate systems of the scanner and ultrasound system--was addressed which reduced the error to 0.36 ± 0.14 mm, sufficient for many preclinical applications.

Development of an assay method to search for compounds inhibiting stress-enhanced allergy

Allergic disorders, such as atopic dermatitis and asthma, become severe or relapse due to stress. As stress is an important factor affecting blood flow (BF), we developed a new assay system based upon our findings on BF decrease in the induction phase of allergy in mice sensitized using egg-white lysozyme (HEL) [1, 2]. Male ddY mice were sensitized i.p. with 12.5, 25 or 50 µg/head of HEL emulsified in complete Freund's adjuvant on 0 day. BF of the venous microcirculation of the tail hypodermic of un-anesthetized mouse was monitored using a Laser Doppler BF Meter of the contact type as previously described [1]. The stress load was given using a modification of the method of Castilla-Ortega E et al [3]. Mice in the stressed groups were restrained 1h or 1.5h daily for 5 – 10 consecutive days in a modified 50 ml clear polystyrene conical centrifuge tube (2.8 cm x11.2 cm in length) with multiple air holes for ventilation. No significant difference of BF decreases between previously reported sensitized mice [1] and stress-enhanced sensitized mice was found. Therefore, we examined the quantity of HEL needed for the sensitization and concluded that we could evaluate stress-enhanced allergy even if the amount of HEL was reduced to 12.5 µg/head. With respect to the stress exposure time, BF showed a significant decrease by the 8th to 10th day on exposure for 60 min/day and by the 5th to 7th day on exposure for 90 min/day. We finally established 90 min/day for 7 days (every other day) as being suitable for an assay system of stress-enhanced allergy. Using this novel assay system, we evaluated natural herbal medicines that are clinically used to treat stress or allergic disorders. Our model should be useful for identifying potential anti-stress-enhanced allergy drugs.

Study of Heat Absorption in Thermoforming for Transparent and Filled Polystyrene

Abstract Heating time and temperature distribution of a semi-finished pre-product are key factors for a satisfying final shape in the thermoforming process. The heating is in most cases done by radiation, which is modelled in simulation by the law of Bouguer Beer Lambert. Two material parameters, the reflection of the surface and the optical penetration depth are needed for the application of this law. One prerequisite for this is that the optical penetration depth is independent of the material thickness. In literature it is very often common to trust on that assumption and to determine it via single measurement of a film or plate with one thickness. The validity of this presumption is investigated for two different polystyrene compounds as part of this work. This assumption was fulfilled for a clear unfilled polystyrene (PS) in a wide range of wavelengths. In contradiction to this, the optical penetration depth of the white filled PS compound is dependent on film thickness. Moreover it increases slightly with film thickness. This deviation is correlated to the strong scattering effect of titanium dioxide contained in this compound.

Glycogen Synthase Kinase 3β Interaction Protein Functions as an A-kinase Anchoring Protein

A-kinase anchoring proteins (AKAPs) include a family of scaffolding proteins that target protein kinase A (PKA) and other signaling proteins to cellular compartments and thereby confine the activities of the associated proteins to distinct regions within cells. AKAPs bind PKA directly. The interaction is mediated by the dimerization and docking domain of regulatory subunits of PKA and the PKA-binding domain of AKAPs. Analysis of the interactions between the dimerization and docking domain and various PKA-binding domains yielded a generalized motif allowing the identification of AKAPs. Our bioinformatics and peptide array screening approaches based on this signature motif identified GSKIP (glycogen synthase kinase 3beta interaction protein) as an AKAP. GSKIP directly interacts with PKA and GSK3beta (glycogen synthase kinase 3beta). It is widely expressed and facilitates phosphorylation and thus inactivation of GSK3beta by PKA. GSKIP contains the evolutionarily conserved domain of unknown function 727. We show here that this domain of GSKIP and its vertebrate orthologues binds both PKA and GSK3beta and thereby provides a mechanism for the integration of PKA and GSK3beta signaling pathways.

Mechanism of Action of an Imidopiperidine Inhibitor of Human Polynucleotide Kinase/Phosphatase

The small molecule, 2-(1-hydroxyundecyl)-1-(4-nitrophenylamino)-6-phenyl-6,7a-dihydro-1H-pyrrolo[3,4-b]pyridine-5,7(2H,4aH)-dione (A12B4C3), is a potent inhibitor of the phosphatase activity of human polynucleotide kinase/phosphatase (PNKP) in vitro. Kinetic analysis revealed that A12B4C3 acts as a noncompetitive inhibitor, and this was confirmed by fluorescence quenching, which showed that the inhibitor can form a ternary complex with PNKP and a DNA substrate, i.e. A12B4C3 does not prevent DNA from binding to the phosphatase DNA binding site. Conformational analysis using circular dichroism, UV difference spectroscopy, and fluorescence resonance energy transfer all indicate that A12B4C3 disrupts the secondary structure of PNKP. Investigation of the potential site of binding of A12B4C3 to PNKP using site-directed mutagenesis pointed to interaction between Trp(402) of PNKP and the inhibitor. Cellular studies revealed that A12B4C3 sensitizes A549 human lung cancer cells to the topoisomerase I poison, camptothecin, but not the topoisomerase II poison, etoposide, in a manner similar to small interfering RNA against PNKP. A12B4C3 also inhibits the repair of DNA single and double strand breaks following exposure of cells to ionizing radiation, but does not inhibit two other key strand-break repair enzymes, DNA polymerase beta or DNA ligase III, providing additional evidence that PNKP is the cellular target of the inhibitor.

Spectrophotometric Determination of Human Immunoglobulin G Based on Enlargement of Gold Nanoparticles

AbstractBased on the sandwich immunoreaction and enlargement of colloidal gold, a simple spectrophotometric determination of human immunoglobulin G (IgG) was developed. The sandwich immunoreaction among the goat‐anti‐human IgG, the human IgG and goat‐anti‐human IgG labeled with colloidal gold was completed on the surface of 96 well clear polystyrene high bind stripwell(tm) microplate. The immobilized colloidal gold was enlarged by the reaction of 0.01% HAuCl4 with 0.4 mmol·L−1 NH2OH·HCl. A common UV‐Vis spectrophotometer was employed to measure the absorption of the colloidal gold enlarged. The absorption signal of colloidal gold is proportional to the logarithm of human IgG concentration ranging from 5.0×10−9 to 2.0×10−5 g·mL−1, which is comparable with those obtained by other immunoassays. In the proposed method, the immobilized colloidal gold can be easily enlarged and a new absorption band is present at about 620 nm, which makes the signal be recorded with a common medical analyzer. This spectrophotometric determination can be made in a common laboratory without the well‐trained technician and the special equipment.

Serum 25-OH Vitamin D2 and D3 are Stable under Exaggerated Conditions

Vitamin D analysis is increasingly performed with HPLC–tandem mass spectrometry instead of RIA, and hence samples are frequently sent to more specialized centers for analysis. We therefore investigated the stability of both 25-OH vitamin D3 (25-OH D3) and 25-OH vitamin D2 (25-OH D2) in serum stored under extreme conditions that would likely exceed those normally encountered in sample transit and storage. After our study received ethics committee approval, we collected 200 mL of blood from a single donor who had given written informed consent and had been previously been determined to have adequate concentrations of 25-OH D3. After centrifugation of the blood sample the serum was removed and supplemented with 50 nmol/L of authentic 25-OH D2 to boost endogenous concentrations. We then transferred 1.0-mL portions into 5-mL clear polystyrene tubes. The sample-containing tubes were capped, stored at −20 °C, and subsequently subjected to various treatments in replicates of 5. These treatments included multiple freeze-thaw cycles (1 to 5 cycles), 8 days at ambient temperature under various conditions, and brief exposure to artificial ultraviolet light. The ambient-temperature storage conditions were as follows: 1 set of 5 samples was left on the laboratory bench uncovered and exposed to fluorescent light and diffuse …

Strong reduction of radiation damage in plastic scintillators by illumination with visible light

The two most important types of radiation damage in plastic scintillators are the production of new stable absorption centers which are responsible for the permanent absorption damage and the deterioration of fluor molecules. The present work shows that both effects can be reduced considerably in the scintillator SCSN-38, if the samples are illuminated during irradiation with light of appropriate wavelength. Illumination of SCSN-38 with red light reduced the deterioration of the fluor BDB by a factor of 2, while the illumination with blue light reduced the permanent absorption damage in SCSN-38 by a factor of 4. A similar reduction of absorption was observed in clear polystyrene, the base material of most plastic scintillators.

Xanthrochromia? By What Method? A Comparison of Visual and Spectrophotometric Xanthrochromia

Most US hospitals use visual inspection for the detection of cerebrospinal fluid xanthrochromia. We compared visual inspection with spectrophotometric xanthrochromia and studied the effect of tube diameter on the sensitivity of visual inspection. Blinded, experienced laboratory technicians visually examined unmarked samples to determine the presence or absence of xanthrochromia. Samples were prepared by lysing RBCs in distilled water. Serial dilutions were placed in clear polystyrene tubes obtained from standard lumbar puncture trays. Laboratory technicians were asked to examine each sample for xanthrochromia using visual inspection. Next, they were asked to interpret the same set of samples with the assistance of a threshold standard. Last, they were asked to interpret the same dilutions, but this time presented in a larger-diameter tube. The absorbance of each sample was measured in a double-beam spectrophotometer at wavelengths between 300 and 700 nm. Samples were said to demonstrate spectrophotometric xanthrochromia if they had an absorbance greater than 0.023 at 415 nm. Sixteen laboratory technicians were shown a total of 160 samples, of which 64 (40%) demonstrated spectrophotometric xanthrochromia. Visual inspection of the samples was 26.6% sensitive (95% confidence interval [CI] 16% to 38%) and 97.9% specific (95% CI 95% to 100%) for spectrophotometric xanthrochromia. Using a reference standard did not improve the performance of visual inspection, but increasing collection-tube diameter increased the sensitivity to 55% (95% CI 43% to 68%). Visual inspection is not sensitive for the detection of spectrophotometric xanthrochromia. Increasing the diameter of the collection tubes did improve sensitivity. Emergency physicians should be aware of how xanthrochromia is determined at their institutions and understand the implications of using visual detection to determine the presence or absence of xanthrochromia.

Reduction of the permanent radiation induced absorption by illumination of plastic scintillators during [formula omitted]-irradiation

Several pieces of the plastic scintillator SCSN-38 were exposed to γ -rays in air and were simultaneously illuminated with visible light. A comparison of illuminated and unilluminated samples showed that the permanent radiation induced absorption was smaller by a factor four when the samples were illuminated with blue light. A similar effect has been observed in clear polystyrene.

Xanthrochromia: By which method? A comparison of the visual and spectrophotometric determination of xanthrochromia

Study objectives: Although spectrophotometric definitions of xanthrochromia exist, nearly all hospitals in the United States use visual inspection for the detection of xanthrochromia. We compare visual inspection for xanthrochromia to the spectrophotometric detection of xanthrochromia. Methods: Laboratory technicians from a tertiary care hospital visually examined unmarked samples for the presence or absence of xanthrochromia. Samples were prepared by vigorously mixing 3 mL of blood with 3 mL of deiodinated water to lyse the RBCs. Dilutions were then made ranging from 1 in 5,000 to 1 in 100,000. Samples of each dilution were placed into clear polystyrene tubes obtained from lumbar puncture trays. In a random sequence, laboratory technicians visually examined each sample for xanthrochromia. In addition, each sample was scanned using a double-beam spectrophotometer (Spectronic Genesis 5, Spectronic Instruments, Rochester, NY) at wavelengths between 300 nm and 700 nm. Absorption was recorded for peaks at 415 nm in allergenic units, the resonant wavelength for oxyhemoglobin. Samples were considered to demonstrate xanthrochromia by spectrophotometry if their absorbance was greater than 0.023 allergenic units at 415 nm. Results: Sixteen laboratory technicians examined a total of 160 samples, of which 64 (40%) demonstrated spectrophotometric xanthrochromia. Visual inspection of the samples was 27% sensitive (95% confidence interval [CI] 16% to 39%) and 98% specific (95% CI 93% to 100%) for spectrophotometric xanthrochromia. Conclusion: Visual inspection is not sensitive for the detection of xanthrochromia. Emergency physicians should understand the limitations of the visual technique in their interpretation of the cerebrospinal fluid analysis of potential subarachnoid hemorrhage patients.

Calculations of electron fluence correction factors using the Monte Carlo code PENELOPE

In electron-beam dosimetry, plastic phantom materials may be used instead of water for the determination of absorbed dose to water. A correction factor ϕwaterplastic is then needed for converting the electron fluence in the plastic phantom to the fluence at an equivalent depth in water. The recommended values for this factor given by AAPM TG-25 (1991 Med. Phys. 18 73–109) and the IAEA protocols TRS-381 (1997) and TRS-398 (2000) disagree, in particular at large depths. Calculations of the electron fluence have been done, using the Monte Carlo code PENELOPE, in semi-infinite phantoms of water and common plastic materials (PMMA, clear polystyrene, A-150, polyethylene, Plastic water™ and Solid water™ (WT1)). The simulations have been carried out for monoenergetic electron beams of 6, 10 and 20 MeV, as well as for a realistic clinical beam. The simulated fluence correction factors differ from the values in the AAPM and IAEA recommendations by up to 2%, and are in better agreement with factors obtained by Ding et al (1997 Med. Phys. 24 161–76) using EGS4. Our Monte Carlo calculations are also in good accordance with ϕwaterplastic values measured by using an almost perturbation-free ion chamber. The important interdependence between depth- and fluence-scaling corrections for plastic phantoms is discussed. Discrepancies between the measured and the recommended values of ϕwaterplastic may then be explained considering the different depth-scaling rules used.

Differences in electron beam dosimetry using two commercial ionization chambers and the TG-21 protocol: Another reason to switch to TG-51

Two of the most popular dosimetry systems used for calibration of megavoltage photon and electron beams in radiation therapy are (i) cylindrical Farmer-type chambers in liquid water and (ii) Holt Memorial parallel-plate chambers in clear polystyrene. Since implementation of the AAPM TG-21 calibration protocol, the Radiological Physics Center (which uses the Farmer in-water system) has compared machine calibrations on two occasions with those of Memorial Sloan-Kettering Cancer Center (which uses the Holt in-polystyrene system). Two years post publication of the TG-51 protocol, 70% of the clinics monitored by the RPC still use TG-21. Seventeen photon beams from cobalt-60 to 18 MV and 31 electron beams from 6 to 20 MeV were compared using the TG-21 protocol. These data represent the most comprehensive comparison of the two most popular systems in use. Based on the average percent difference, the two systems yielded the same absorbed dose to water at the reference point in phantom to within 1.5% for both modalities. No energy dependence was evident in the results; however, a systematic average percent difference between photons and electrons was seen, with the Farmer in-water system consistently predicting a dose 1.3% lower for electrons than the Holt in-polystyrene system. For photons both systems predicted the same dose to within 0.3% on average. When a physicist converts from TG-21 to TG-51, these data may be of assistance in explaining unexpected changes in output that are different from previously published values. Implementation of the TG-51 protocol should eliminate any of the observed differences in electron beam dosimetry between the two dosimetry systems because the Holt system cannot be used with TG-51. PACS number(s): 87.53.-j, 87.53.-j