scholarly journals Bioorganometallic Technetium and Rhenium Chemistry: Fundamentals for Applications

2020 ◽  
Vol 74 (12) ◽  
pp. 953-959
Author(s):  
Roger Alberto ◽  
Henrik Braband ◽  
Qaisar Nadeem
Keyword(s):  
Coordination Chemistry ◽  
Molecular Imaging ◽  
Periodic System ◽  
Half Life ◽  
Advanced Education ◽  
Practical Applications ◽  
Excellent Opportunity ◽  
The Impact ◽  
Frequent Observation ◽  
Oriented Research

Due to its long half-life of 2.111×105 y, technetium, i.e. 99Tc, offers the excellent opportunity of combining fundamental and ' classical ' organometallic or coordination chemistry with all methodologies of radiochemistry. Technetium chemistry is inspired by the applications of its short-lived metastable isomer 99mTc in molecular imaging and radiopharmacy. We present in this article examples about these contexts and the impact of purely basic oriented research on practical applications. This review shows how the chemistry of this element in the middle of the periodic system inspires the chemistry of neighboring elements such as rhenium. Reasons are given for the frequent observation that the chemistries of 99Tc and 99mTc are often not identical, i.e. compounds accessible for 99mTc, under certain conditions, are not accessible for 99Tc. The article emphasizes the importance of macroscopic technetium chemistry not only for research but also for advanced education in the general fields of radiochemistry.

Social Buffering as a Tool for Improving Rodent Welfare

2021 ◽  
Author(s):  
Melanie R Denommé ◽  
Georgia J Mason
Keyword(s):  
Conditioned Fear ◽  
Companion Animals ◽  
Social Contact ◽  
Practical Applications ◽  
Social Buffering ◽  
Laboratory Rodents ◽  
Mere Presence ◽  
The Impact ◽  
Further Development ◽  
Oriented Research

The presence of a conspecific can be calming to some species of animal during stress, a phenomenon known as social buffering. For rodents, social buffering can reduce the perception of and reaction to aversive experiences. With a companion, animals may be less frightened in conditioned fear paradigms, experience faster wound healing, show reduced corticosterone responses to novelty, and become more resilient to everyday stressors like cage-cleaning. Social buffering works in diverse ways across species and life stages. For example, social buffering may rely on specific bonds and interactions between individuals, whereas in other cases, the mere presence of conspecific cues may reduce isolation stress. Social buffering has diverse practical applications for enhancing rodent wellbeing (some of which can be immediately applied, while others need further development via welfare-oriented research). Appropriate social housing will generally increase rodents’ abilities to cope with challenges, with affiliative cage mates being the most effective buffers. Thus, when rodents are scheduled to experience distressing research procedures, ensuring that their home lives supply high degrees of affiliative, low stress social contact can be an effective refinement. Furthermore, social buffering research illustrates the stress of acute isolation: stressors experienced outside the cage may thus be less impactful if a companion is present. If a companion cannot be provided for subjects exposed to out-of-cage stressors, odors from unstressed animals can help ameliorate stress, as can proxies such as pieces of synthetic fur. Finally, in cases involving conditioned fear (the learned expectation of harm), newly providing social contact during exposure to negative conditioned stimuli (CS) can modify the CS such that for research rodents repeatedly exposed to aversive stimuli, adding conspecific contact can reduce their conditioned fear. Ultimately, these benefits of social buffering should inspire the use of creative techniques to reduce the impact of stressful procedures on laboratory rodents, so enhancing their welfare.

scholarly journals The Impact of Lipid Handling and Phase Distribution on the Acoustic Behavior of Microbubbles

Pharmaceutics ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 119
Author(s):  
Simone A.G. Langeveld ◽  
Inés Beekers ◽  
Gonzalo Collado-Lara ◽  
Antonius F. W. van der Steen ◽  
Nico de Jong ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Molecular Imaging ◽  
High Speed ◽  
Phase Distribution ◽  
Direct Method ◽  
Ultrasound Contrast Agents ◽  
Lipid Phase ◽  
Acoustic Behavior ◽  
Ultrasound Molecular Imaging ◽  
The Impact

Phospholipid-coated microbubbles are ultrasound contrast agents that can be employed for ultrasound molecular imaging and drug delivery. For safe and effective implementation, microbubbles must respond uniformly and predictably to ultrasound. Therefore, we investigated how lipid handling and phase distribution affected the variability in the acoustic behavior of microbubbles. Cholesterol was used to modify the lateral molecular packing of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)-based microbubbles. To assess the effect of lipid handling, microbubbles were produced by a direct method, i.e., lipids directly dispersed in an aqueous medium or indirect method, i.e., lipids first dissolved in an organic solvent. The lipid phase and ligand distribution in the microbubble coating were investigated using confocal microscopy, and the acoustic response was recorded with the Brandaris 128 ultra-high-speed camera. In microbubbles with 12 mol% cholesterol, the lipids were miscible and all in the same phase, which resulted in more buckle formation, lower shell elasticity and higher shell viscosity. Indirect DSPC microbubbles had a more uniform response to ultrasound than direct DSPC and indirect DSPC-cholesterol microbubbles. The difference in lipid handling between direct and indirect DSPC microbubbles significantly affected the acoustic behavior. Indirect DSPC microbubbles are the most promising candidate for ultrasound molecular imaging and drug delivery applications.

Geometry Design and Contact Ratio Analysis for Circular Arc Parallel-Axis Helical Gears

2016 ◽  
Author(s):  
Z. Chen ◽  
B. Lei ◽  
Q. Zhao
Keyword(s):  
Rolling Process ◽  
Helical Gear ◽  
Space Curve ◽  
Impact Factors ◽  
Contact Ratio ◽  
Circular Arc ◽  
Practical Applications ◽  
Geometry Design ◽  
Gear Mechanism ◽  
The Impact

Based on space curve meshing theory, in this paper, we present a novel geometric design of a circular arc helical gear mechanism for parallel transmission with convex-concave circular arc profiles. The parameter equations describing the contact curves for both the driving gear and the driven gear were deduced from the space curve meshing equations, and parameter equations for calculating the convex-concave circular arc profiles were established both for internal meshing and external meshing. Furthermore, a formula for the contact ratio was deduced, and the impact factors influencing the contact ratio are discussed. Using the deduced equations, several numerical examples were considered to validate the contact ratio equation. The circular arc helical gear mechanism investigated in this study showed a high gear transmission performance when considering practical applications, such as a pure rolling process, a high contact ratio, and a large comprehensive strength.

Managing uncertainty in a general insurance company

1990 ◽  
Vol 117 (2) ◽  
pp. 173-277 ◽  
Author(s):  
C. D. Daykin ◽  
G. B. Hey
Keyword(s):  
Computer Model ◽  
Flow Model ◽  
Insurance Companies ◽  
Simulation Methods ◽  
Insurance Company ◽  
Practical Applications ◽  
General Insurance ◽  
Alternative Approaches ◽  
The Impact

AbstractA cash flow model is proposed as a way of analysing uncertainty in the future development of a general insurance company. The company is modelled alongside the market in aggregate so that the impact of changes in premium rates relative to the market can be assessed. An extensive computer model is developed along these lines, intended for use in practical applications by actuaries advising the management of genera1 insurance companies. Simulation methods are used to explore the consequences of uncertainty, particularly in regard to inflation and investments. Some comments are made on the role of actuaries in general insurance. Alternative approaches to describing the behaviour of an insurance firm in the market are considered.

scholarly journals Polytetrafluoroethylene Films in Rigid Polyurethane Foams’ Dielectric Permittivity Measurements with a One-Side Access Capacitive Sensor

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1173
Author(s):  
Ilze Beverte ◽  
Ugis Cabulis ◽  
Sergejs Gaidukovs
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Low Frequency ◽  
Capacitive Sensor ◽  
Polyurethane Foams ◽  
Active Area ◽  
Ptfe Film ◽  
Practical Applications ◽  
Permittivity Measurements ◽  
The Impact

As a non-metallic composite material, widely applied in industry, rigid polyurethane (PUR) foams require knowledge of their dielectric properties. In experimental determination of PUR foams’ dielectric properties protection of one-side capacitive sensor’s active area from adverse effects caused by the PUR foams’ test objects has to be ensured. In the given study, the impact of polytetrafluoroethylene (PTFE) films, thickness 0.20 mm and 0.04 mm, in covering or simulated coating the active area of one-side access capacitive sensor’ electrodes on the experimentally determined true dielectric permittivity spectra of rigid PUR foams is estimated. Penetration depth of the low frequency excitation field into PTFE and PUR foams is determined experimentally. Experiments are made in order to evaluate the difference between measurements on single PUR foams’ samples and on complex samples “PUR foams + PTFE film” with two calibration modes. A modification factor and a small modification criterion are defined and values of modifications are estimated in numerical calculations. Conclusions about possible practical applications of PTFE films in dielectric permittivity measurements of rigid PUR foams with one-side access capacitive sensor are made.

scholarly journals Feminist Methods and Sources in Criminology and Criminal Justice

2016 ◽  
Vol 16 (2) ◽  
pp. 102-107 ◽  
Author(s):  
Adrian Howe
Keyword(s):  
Social Sciences ◽  
Criminal Justice ◽  
Advanced Education ◽  
Justice Research ◽  
Legal Studies ◽  
The Social ◽  
Feminist Methods ◽  
Criminal Justice Research ◽  
The Impact ◽  
Criminology And Criminal Justice

AbstractThis article by Adrian Howe is based on a presentation given at the ‘Sources and Methods in Criminology and Criminal Justice Conference’ in November 2015, jointly sponsored by the Institute of Advanced Education and the Socio-Legal Studies Association. She begins by querying whether there are indeed distinct feminist methods in the social sciences. She outlines the impact of what she calls the ‘methodical revolution’ on the criminology discipline, Foucault's contribution and Foucauldian methodologies deployed in criminological and criminal justice research.

scholarly journals The Influence of YouTube Beauty Vloggers on Indonesian Consumers’ Purchase Intention of Local Cosmetic Products

2020 ◽  
Vol 15 (5) ◽  
pp. 100
Author(s):  
Jui-Lung Chen ◽  
Apritika Dermawan
Keyword(s):  
Social Media ◽  
Information Exchange ◽  
Purchase Intention ◽  
Future Research ◽  
Web Based ◽  
Practical Applications ◽  
Mainstream Media ◽  
Marketing Tool ◽  
Willingness To Purchase ◽  
The Impact

Social media are web-based technology and social platform that involve social, personal and technological factors, which have triggered the development and evolution of website-based communities. Moreover, relevant web-based applications have also become the mainstream media for value creation and information exchange. The proliferation, convenience, and immediacy of social media have attracted many enterprises to adopt social media as a marketing tool. Among them, Electronic Word-of-Mouth (E-WoM), used mostly by vloggers (video bloggers), enables its users to review products and express their opinions on social media. Therefore, E-WoM has gradually become an important source of information for consumers, which influences their purchasing decisions. YouTube, a video sharing platform affiliated with Google, is a popular social media with tons of users. One of its most appealing and popular communities is Beauty Blogger, where beauty vloggers create and upload videos about beauty products. This study explored the impact of YouTube beauty vlogger on the attitude of Indonesian women towards locally made cosmetics and their willingness to purchase them. Based on the research results, relevant conclusions and recommendations were proposed which can be used as a reference for future research and practical applications.

scholarly journals A psychrometric model to assess the biological decay of the SARS-CoV-2 virus in aerosols

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11024
Author(s):  
Clive B. Beggs ◽  
Eldad J. Avital
Keyword(s):  
Air Temperature ◽  
Vapour Pressure ◽  
Half Life ◽  
Analytical Study ◽  
Decay Constant ◽  
Meteorological Data ◽  
Environmental Parameters ◽  
Published Data ◽  
Reasonable Accuracy ◽  
The Impact

There is increasing evidence that the 2020 COVID-19 pandemic has been influenced by variations in air temperature and humidity. However, the impact that these environmental parameters have on survival of the SARS-CoV-2 virus has not been fully characterised. Therefore, an analytical study was undertaken using published data to develop a psychrometric model to assess the biological decay rate of the virus in aerosols. This revealed that it is possible to describe with reasonable accuracy (R2 = 0.718, p < 0.001) the biological decay constant for the SARS-CoV-2 virus using a regression model with enthalpy, vapour pressure and specific volume as predictors. Applying this to historical meteorological data from London, Paris and Milan over the pandemic period, produced results which indicate that the average half-life of the virus in aerosols outdoors was in the region 13–22 times longer in March 2020, when the outbreak was accelerating, than it was in August 2020 when epidemic in Europe was at its nadir. However, indoors, this variation is likely to be much less. As such, this suggests that changes in virus survivability due the variations in the psychrometric qualities of the air might influence the transmission of SARS-CoV-2.

Beta-decay half-lives of the extremely neutron-rich nuclei in the closed-shell N = 50, 82, 126 groups

2021 ◽  
Author(s):  
Nguyen Kim Uyen ◽  
Kyung Yuk Chae ◽  
NgocDuy Nguyen ◽  
DuyLy Nguyen
Keyword(s):  
Half Life ◽  
Random Phase ◽  
Closed Shell ◽  
Decay Rates ◽  
Magic Numbers ◽  
Β Decay ◽  
R Process ◽  
Neutron Rich Isotopes ◽  
Semi Empirical ◽  
The Impact

Abstract The β--decay half-lives of extremely neutron-rich nuclei are important for understanding nucleosynthesis in the r-process. However, most of their half-lives are unknown or very uncertain, leading to the need for reliable calculations. In this study, we updated the coefficients in recent semi-empirical formulae using the newly updated mass (AME2020) and half-life (NUBASE2020) databases to improve the accuracy of the half-life prediction. In particular, we developed a new empirical model for better calculations of the β--decay half-lives of isotopes ranging in Z = 10 – 80 and N = 15-130. We examined the β--decay half-lives of the extremely neutron-rich isotopes at and around the neutron magic numbers of N = 50, 82, and 126 using either five different semi-empirical models or finite-range droplet model and quasi-particle random phase approximation (FRDM+QRPA) method. The β--decay rates derived from the estimated half-lives were used in calculations to evaluate the impact of the half-life uncertainties of the investigated nuclei on the abundance of the r-process. The results show that the half-lives mostly range in 0.001 < T1/2 < 100 s for the nuclei with a ratio of N/Z < 1.9; however, they differ significantly for those with the ratio of N/Z > 1.9. The half-life differences among the models were found to range from a few factors (for N/Z < 1.9 nuclei) to four orders of magnitude (for N/Z > 1.9). These discrepancies lead to a large uncertainty, which is up to four orders of magnitude, in the r-process abundance of isotopes. We also found that the multiple-reflection time-of-flight (MR-TOF) technique is preferable for precise mass measurements because its measuring timescale applies to the half-lives of the investigated nuclei. Finally, the results of this study are useful for studies on the β-decay of unstable isotopes and astrophysical simulations.

Predictability of Elimination and Excretion of Small Molecules from Animals to Humans, and Impact on Dosimetry for human ADME Studies with Radiolabeled Drugs

2021 ◽  
Vol 16 ◽  
Author(s):  
Ad Roffel ◽  
Jan Jaap van Lier ◽  
Gerk Rozema ◽  
Ewoud-Jan van Hoogdalem
Keyword(s):  
Small Molecules ◽  
Half Life ◽  
Fecal Excretion ◽  
Radiation Burden ◽  
Quantitative Correlation ◽  
Elimination Half ◽  
The Impact ◽  
Plasma Half Life ◽  
Entire Dataset ◽  
Actual Radiation

Background: We assessed the extent to which urinary and fecal excretion of 14C-labeled drug material in animal ADME studies was predictive of human ADME studies. We compared observed plasma elimination half lives for total drug related radioactivity in humans to pre-study predictions, and we estimated the impact of any major differences on human dosimetry calculations. Methods: We included 34 human ADME studies with doses of 14C above 0.1 MBq. We calculated ratios of dosimetry input parameters (percentage fecal excretion in humans versus animals; observed half life in humans versus predicted pre-study) and output parameters (effective dose post-study versus pre study) and assessed their relationship. Results: A quantitative correlation assessment did not show a statistically significant correlation between the ratios of percentages of 14C excreted in feces and the ratios of dosimetry outcomes in the entire dataset, but a statistically significant correlation was found when assessing the studies that were based on ICRP 60/62 (n=19 studies; P=0.0028). There also appeared to be a correlation between the plasma half-life ratios and the ratios of dosimetry results. A quantitative correlation assessment showed that there was a statistically significant correlation between these ratios (P<0.0001). Conclusion: In all cases where the plasma elimination half-life for 14C in humans was found to be longer than the predicted value, the radiation burden was still within ICRP Category IIa. Containment of the actual radiation burden below the limit of 1.00 mSv appeared to be determined partly also by our choice to limit 14C doses to 3.7 MBq.

Sign in / Sign up

Export Citation Format

Share Document