2,679 research outputs found
Simulations of the temporal and spatial resolution for a compact time-resolved electron diffractometer
A novel compact electron gun for use in time-resolved gas electron diffraction experiments has recently been designed and commissioned. In this paper we present and discuss the extensive simulations that were performed to underpin the design in terms of the spatial and temporal qualities of the pulsed electron beam created by the ionisation of a gold photocathode using a femtosecond laser. The response of the electron pulses to a solenoid lens used to focus the electron beam has also been studied. The simulated results show that focussing the electron beam affects the overall spatial and temporal resolution of the experiment in a variety of ways, and that factors that improve the resolution of one parameter can often have a negative effect on the other. A balance must, therefore, be achieved between spatial and temporal resolution. The optimal experimental time resolution for the apparatus is predicted to be 416 fs for studies of gas-phase species, while the predicted spatial resolution of better than 2 nm-1 compares well with traditional time-averaged electron diffraction set-ups
Quantifying Forest Ground Flora Biomass Using Proximal Sensing
Current focus on forest conservation and forest sustainability has increased the level of attention given to measures of ground flora in forest ecosystems. Traditionally, such data are collected via time- and resource-intensive methods of field identification, clipping, and weighing. With increased focus on community composition and structure measures of forest ground flora, the manner in which these data are collected must change. This project uses color and color infrared digital cameras to proximally sense forest ground flora and to develop regression models to predict green and dry biomass (g/m^) from the proximally sensed data. Traditional vegetative indices such as the Normalized Difference Vegetative Index (NDVI) and the Average Visible Reflectance Index (AVR) explained 35-45% of the variation in forest ground flora biomass. Adding individual color band variables, especially the red and near infrared bands, to the regression model allowed the model to explain 66% and 58% of the variation in green and dry biomass, respectively, present
Alignment facility and software for single crystal time of flight neutron spectroscopy
An instrument and software algorithm is described for the purpose of
characterization of large single crystals at the Alignment Facility (ALF) of
the ISIS spallation neutron source. We describe a method for both
characterizing the quality of the sample and also aligning it in a particular
scattering plane. We present a software package written for this instrument and
demonstrate its utility by way of an example of the structural characterization
of large singles crystals of Pb(MgNb)O. We suggest
extensions and modifications of characterization instruments for future
improved beamlines. It is hoped that this software will be used by the neutron
user community for pre characterizing large single crystals for spectroscopy
experiments and that future facilities will include such a facility as part of
the spectroscopy suite at spallation neutron sources.Comment: (6 pages, 7 figures, to be published in Journal of Applied
Crystallography); The software package can be found at
https://github.com/CSTOCK3/ALF-Analysis-Software. Please email comments to
the author
Unusual cage rearrangements in 10-vertex nido-5,6-dicarbaborane derivatives : An interplay between theory and experiment
The reaction between selected X-nido-5,6-C2B8H11 compounds (where X = Cl, Br, I) and "Proton Sponge" [PS; 1,8-bis(dimethylamino)naphthalene], followed by acidification, results in extensive rearrangement of all cage vertices. Specifically, deprotonation of 7-X-5,6-C2B8H11 compounds with one equivalent of PS in hexane or CH2Cl2 at ambient temperature led to a 7 → 10 halogen rearrangement, forming a series of PSH+[10-X-5,6-C2B8H10]- salts. Reprotonation using concentrated H2SO4 in CH2Cl2 generates a series of neutral carbaboranes 10-X-5,6-C2B8H11, with the overall 7 → 10 conversion being 75%, 95%, and 100% for X = Cl, Br, and I, respectively. Under similar conditions, 4-Cl-5,6-C2B8H11 gave ∼66% conversion to 3- Cl-5,6-C2B8H11. Since these rearrangements could not be rationalized using the Bvertex swing mechanism, new cage rearrangement mechanisms, which are substantiated using DFT calculations, have been proposed. Experimental 11B NMR chemical shifts are well reproduced by the computations; as expected δ(11B) for B(10) atoms in derivatives with X = Br and I are heavily affected by spin-orbit coupling
A compact electron gun for time-resolved electron diffraction
A novel compact time-resolved electron diffractometer has been built with the primary goal of studying the ultrafast molecular dynamics of photoexcited gas-phase molecules. Here, we discuss the design of the electron gun, which is triggered by a Ti:Sapphire laser, before detailing a series of calibration experiments relating to the electron-beam properties. As a further test of the apparatus, initial diffraction patterns have been collected for thin, polycrystalline platinum samples, which have been shown to match theoretical patterns. The data collected demonstrate the focusing effects of the magnetic lens on the electron beam, and how this relates to the spatial resolution of the diffraction pattern
Low dose effects of ethanol on suckling rats: Enzymes activity, histological alterations and growth parameters.
زمینه و هدف: غلظت های پایین اتانول می توانند از طریق جفت به جنین و از طریق شیر مادر به نوزاد تازه متولد شده منتقل شوند. این مطالعه با هدف بررسی اثرات دوزهای مختلف اتانول در طول دوره شیردهی بر تغییرات آنزیمی، بافتی و شاخص های رشد نوزادان شیرخوار در موش صحرایی انجام شد. روش بررسی: در این مطالعه تجربی، 21 سر موش صحرایی ماده بالغ نژاد ویستار به سه گروه شامل دو گروه تیمار و یک گروه شاهد تقسیم شدند. به گروه های تیمار از روز یک زایمان تا روز 24 شیردهی آب آشامیدنی به همراه اتانول با غلظت حجمی 2 و 4 درصد تجویز شد و گروه شاهد تنها به آب آشامیدنی دسترسی داشتند. از هر گروه، 9 سر نوزاد موش صحرایی 25 روزه انتخاب و فعالیت سرمی آنزیم های آلانین آمینوترانسفراز، گاماگلوتامیک ترانسفراز، آسپارتات آمینوترانسفراز، آلکالین فسفاتاز، لاکتات دهیدروژناز، کراتین فسفوکیناز، نیتروژن اوره خون و کراتینین اندازه گیری شدند. همچنین مطالعات آسیب شناسی بر روی بافت های مغز، کبد و کلیه انجام شد. داده ها به کمک آزمون های آماری آنالیزواریانس و تست دانت در نرم افزار SPSS تجزیه و تحلیل شدند. یافته ها: در گروه های تجربی میزان فعالیت سرمی آنزیم های آلانین آمینوترانسفراز، آسپارتات آمینوترانسفراز، نیتروژن اوره خون، کراتین فسفوکیناز و آلکالین فسفاتاز اختلاف معنی داری را نسبت به گروه شاهد نشان ندادند (05/0P). مطالعات هیستوپاتولوژیک آسیب های مختلفی را در بافت مغز، کبد و کلیه نوزادان در معرض اتانول 4 حجمی را نشان داد. نتیجه گیری: بر اساس نتایج این مطالعه، مصرف نوشیدنی های الکلی در دوران شیردهی می تواند ضایعات جبران ناپذیری بر روی نوزاد داشته باشد
At an important tephrostratigraphic crossroads: cryptotephra in Late Glacial to Early Holocene lake sediments from the Carpathian Mountains, Romania
Understanding the temporal and spatial environmental response to past climate change during the Last Glacial-Interglacial Transition (LGIT, 16-8 ka) across Europe relies on precise chronologies for palaeoenvironmental records. Tephra layers (volcanic ash) are a powerful chronological tool to synchronise disparate records across the continent. Yet, some regions remain overlooked in terms of cryptotephra investigations. Building on earlier work at the same sites, we present the first complete LGIT high-resolution cryptotephra investigation of two lake records in the Carpathian Mountains in Romania, Lake Brazi and Lake Lia. Numerous volcanic glass shards have been recognised as originating from various volcanic regions, including: Iceland (Katla, Askja, and Torfajokull), Italy (Campi Flegrei, Ischia, Lipari, and Pantelleria), and central Anatolia (Acigol and Ericyes). In total, four distinct tephra horizons have now been identified in these records: 1) an LGIT Lipari tephra (11,515–12,885 cal BP, 95.4% range); 2) Askja-S (11,070–10,720 cal BP, 95.4% range); 3) an Early Holocene Lipari tephra,(12,590–10,845 cal BP, 95.4% range) and; 4) an Early Holocene Ischia tephra (11,120–10,740 cal BP, 95.4% range). The use of trace element analysis on selected cryptotephra layers provided additional important information in identifying volcanic source and facilitating correlations. These tephra layers, along with numerous other discrete cryptotephra layers, offer promise as significant future isochrons for comprehending the spatial and temporal fluctuations in past climate change throughout Europe and the Mediterranean area. This research has emphasized the significance of the Carpathian region in expanding the European and Mediterranean tephra lattice and establishing it as a keystone area within the framework
High Pressure Processing of Dairy Foods
End of Project ReportThe term High Pressure Processing (HPP) is used to describe the technology whereby
products are exposed to very high pressures in the region of 50 - 800 MPa (500 - 8000
Atmospheres). The potential application of HPP in the food industry has gained popularity
in recent years, due to developments in the construction of HPP equipment which makes
the technology more affordable. Applying HPP to food products results in modifications to
interactions between individual components, rates of enzymatic reactions and inactivation
of micro-organisms.
The first commercial HPP products appeared on the market in 1991 in Japan, where HPP
is now being used commercially for products such as jams, sauces, fruit juices, rice cakes
and desserts. The pioneering research into the application of HPP to milk dates back to the
end of the 19th century. Application of HPP to milk has been shown to modify its gel
forming characteristics as well as reducing its microbial load. HPP offers the potential to
induce similar effects to those generated by heat on milk protein.
Recent reports have also indicated that HPP could accelerate the ripening of cheese. Much
of the Irish cheese industry is based on the production of Cheddar cheese, the ripening time
for which can vary from 4 - 12 months or more, depending on grade. A substantial portion
of the cost associated with Cheddar manufacture is therefore attributed to storage under
controlled conditions during ripening. Thus, any technology which may accelerate the
ripening of Cheddar cheese while maintaining a balanced flavour and texture is of major
economic significance.
While food safety is a dominant concern, consumers are increasingly demanding foods that
maintain their natural appearance and flavour, while free of chemical preservatives. HPP
offers the food industry the possibility of achieving these twin goals as this technology can
lead to reduced microbial loads without detrimentally effecting the nutritional or sensory
qualities of the product.
The development of food ingredients with novel functional properties offers the dairy
industry an opportunity to revitalise existing markets and develop new ones. HPP can lead
to modifications in the structure of milk components, in particular protein, which may
provide interesting possibilities for the development of high value nutritional and functional
ingredients.
Hence these projects set out to investigate the potential of HPP in the dairy industry and
to identify products and processes to which it could be applied.Department of Agriculture, Food and the Marin
Panel 1: Pilot Supply & Industry Consequences Update
Update on current “State Of The Industry” in each panelist’s area of expertise. Panelists are asked to provide a brief perspective on current status, trends, and areas of dynamic change. Aviation Academic Status Macchiarella (ERAU) Regional Airlines Greubel (ExpressJet), Haugaard (Horizon Air), Dee (Republic), Lane (Allegiant) Major Airlines Buyer (United), Winter (JetBlue) ALPA Ryder Air Carrier Training Aviation Rulemaking Committee (ACT/ARC) Duncan (FAA) World Pilot Demand, Trends, Forecasts Davis (Boeing) Report From the Hill Bechdolt (RAA
- …