Saturated fat

A saturated fat is a type of fat in which the fatty acid chains have all single bonds. A fat known as a glyceride is made of two kinds of smaller molecules: a short glycerol backbone and fatty acids that each contain a long linear or branched chain of carbon (C) atoms. Along the chain, some carbon atoms are linked by single bonds (-C-C-) and others are linked by double bonds (-C=C-). A double bond along the carbon chain can react with a pair of hydrogen atoms to change into a single -C-C- bond, with each H atom now bonded to one of the two C atoms. Glyceride fats without any carbon chain double bonds are called saturated because they are "saturated with" hydrogen atoms, having no double bonds available to react with more hydrogen. Most animal fats are saturated. The fats of plants and fish are generally unsaturated. Various foods contain different proportions of saturated and unsaturated fat. Many processed foods like foods deep-fried in hydrogenated oil and s

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Fat

In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. Th

Fatty acid

In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranche

Triglyceride

A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from tri- and glyceride). Triglycerides are the main constituents of body fat

Automated Raman Lidar for Day and Night Operational Observation of Tropospheric Water Vapor for Meteorological Applications

Todor Dinoev

Water vapor is a fundamental constituent of the atmosphere and is the most abundant green house gas thus having an important influence on climate. It is as well a key prognostic variable for numerical weather prediction models (NWP). Currently, the vertical profiles of tropospheric water vapor are provided by twice a day radiosondes. The routine observations have rather low temporal resolution that is insufficient to resolve fast-running meteorological phenomena. The aim of the thesis work was to design and build a Raman lidar instrument capable of continuous vertical profiling of tropospheric water vapor field with high temporal and vertical resolution. The provided observations will improve the database available for direct meteorological applications and could increase the accuracy of numerical weather prediction. RALMO – RAman Lidar for Meteorological Observations is developed as fully automated, eye-safe instrument for operational use by the Swiss meteorological service – MeteoSwiss. The lidar is able to provide vertical profiles of water vapor mixing ratio with time resolution from 5 to 30 min and vertical resolution from 15 m in boundary layer and 75 – 500 m in free troposphere. The daytime vertical operational range of the lidar extends from about 50 m to mid-troposphere and the detection limit is 0.5 g/kg. In night-time conditions the vertical operational range extends up to the tropopause with 0.01 g/kg detection limit. To allow daytime operation with extended vertical range and required detection limit the lidar is designed with narrow field-of-view receiver, narrow band detection, and it uses high pulse power laser with wavelength in the UV but out of solar blind region. The lidar transmitter uses flash-lamps pumped frequency tripled Nd: YAG laser generating 8 ns pulses with 0.3 J energy and 355 nm wavelength. To reduce the beam irradiance, required for eye-safe operation, and to reduce the divergence required for narrow field of view receiver, the laser beam is expanded by 15x refractive type expander. The backscattered laser light is collected by four 30 cm in diameter telescopes with focal length of 1 m. For better long term alignment stability the telescopes are tightly arranged around the beam expander in compact assembly. The field-of-view of the telescopes is reduced to 0.2 mrad to decrease the collected sky-scattered sunlight thus allowing daytime measurements up to mid troposphere. Fibers transmit the light collected by the telescopes to the lidar polychromator. Fiber coupling was preferred against free space connection because it separates the units mechanically and increases the overall lidar stability. In addition the fibers perform aperture scrambling which prevents range dependence of the receiver parameters. An additional "near range" fiber is installed in one of the telescopes to enhance the near range signal and to allow daytime measurements starting from approximately 50 m above the lidar. A high throughput diffraction grating polychromator is designed for narrow band isolation of water vapor, nitrogen, and oxygen Q branches of ro-vibrational Raman spectra. Water vapor mixing ratio is derived from the ratio of water vapor to nitrogen Raman signals and the oxygen signal is used to correct for aerosol differential extinction at water and nitrogen wavelengths. The water vapor detection channel passband is 0.3 nm. The narrow band detection increases the lidar sensitivity and operational range in daytime conditions. For maximum throughput of the polychromator, the exit and entrance slits are matched and the polychromator entrance accepts the divergent beam from the fibers without losses. Photomultipliers at the exit of the polychromator detect the Raman lidar signals, which are then acquired by transient recorders (Licel). The signals are simultaneously recorded in analog and photon-counting modes. The analog signals are used in daytime conditions with sky background signal that saturates completely the photon counter, whereas in night-time conditions, photon counting signals are used. Two computers provide for the automated operation of the lidar instrument. The first one controls all lidar units relevant to the lidar operation, including the laser and the data acquisition. For this purpose, Lidar Automat software has been developed under LabView and requires only activation by an operator. Automated data treatment software, developed under Matlab, is run on the second lidar computer. It reads the initial lidar data, treats them, and stores the final result in files ready for upload to the meteorological service. The files contain vertical profiles of water vapor mixing ratio and relative error. The lidar was completed in July 2007 and installed at the aerological station of MeteoSwiss in Payerne. Since October 2007 the lidar has been in experimental operation and the software for automated data treatment was completed. Since September 2008 the instrument has been fully operational, providing continuous vertical water vapor mixing ratio profiles uploaded to MeteoSwiss every 30 min. Regular comparisons with Vaisala RS-92 and Snow White® radiosondes were performed during the experimental lidar operation at Payerne. Long-term stability study of the calibration coefficient was performed as well.

EPFL2009

Life cycle environmental assessment of retaining walls in unsaturated soils

Alessio Ferrari, Gianluca Speranza

Retaining structures above groundwater level support soils that are usually in a state of partial saturation and subject to the actions of atmospheric agents. The current design approach considers the possible extremes of soil conditions - either totally dry or totally saturated - but it neglects matric suction's contribution to soil shear strength. This work aims to describe how unsaturated-soil mechanics of can positively influence the sustainability of retaining structures through a holistic, multidisciplinary, geotechnical, and environmental analysis. The geotechnical analysis allows to estimate the lateral earth pressure of a geostructure in both unsaturated and extreme soil conditions (dry or saturated), which will directly influence the geometrical dimensions of the geostructure. Next, the environmental analysis is performed with the standardized and globally applied Life Cycle Assessment (LCA) tool, in order to quantify the potential environmental impacts of the retaining structure according to both a life cycle and a multi-criteria perspective. First, an LCA model is built for a cantilever retaining wall according to two design approaches: (a) an unsaturated design approach (UDA), i.e. when unsaturated soils' principles are considered in the design procedure, and (b) a conventional design approach (CDA), i.e. if soil is considered dry or saturated. Three different types of retained soil (i.e. fine-grained soil, volcanic ash, and coarse-grained soil) are considered. Then, the associated environmental impacts on climate change, human health, ecosystems and resources are calculated for the two design approaches. Their comparison allows to quantify the potential reductions in environmental damages provided by the adoption of unsaturated-soil mechanics. The presented case study shows a high potential reduction in environmental impacts for retaining walls interacting with fine-grained soils (silt), lower potential environmental benefits with volcanic ash (clayey-silty sand), but no environmental gain for interaction with a coarse-grained soil (sand) compared to a conventional design approach considering extreme soil conditions. (c) 2021 Elsevier Ltd. All rights reserved.

ELSEVIER2022

DLL4 promotes continuous adult intestinal lacteal regeneration and dietary fat transport

Freddy Radtke, Simone Ragusa, Stefanie Siegert

The small intestine is a dynamic and complex organ that is characterized by constant epithelium turnover and crosstalk among various cell types and the microbiota. Lymphatic capillaries of the small intestine, called lacteals, play key roles in dietary fat absorption and the gut immune response; however, little is known about the molecular regulation of lacteal function. Here, we performed a high-resolution analysis of the small intestinal stroma and determined that lacteals reside in a permanent regenerative, proliferative state that is distinct from embryonic lymphangiogenesis or quiescent lymphatic vessels observed in other tissues. We further demonstrated that this continuous regeneration process is mediated by Notch signaling and that the expression of the Notch ligand delta-like 4 (DLL4) in lacteals requires activation of VEGFR3 and VEGFR2. Moreover, genetic inactivation of Dll4 in lymphatic endothelial cells led to lacteal regression and impaired dietary fat uptake. We propose that such a slow lymphatic regeneration mode is necessary to match a unique need of intestinal lymphatic vessels for both continuous maintenance, due to the constant exposure to dietary fat and mechanical strain, and efficient uptake of fat and immune cells. Our work reveals how lymphatic vessel responses are shaped by tissue specialization and uncover a role for continuous DLL4 signaling in the function of adult lymphatic vasculature.

American Society for Clinical Investigation2015

BIO-207: Cellular and molecular biology II

This course is aimed to familiarize students with the 3D organization of a eukaryotic cell, its compartmentalization, how cellular compartments communicate together and how a cell communicates with its environment. The related molecular mechanisms will be discussed.

BIO-105: Cellular biology and biochemistry for engineers

Basic course in biochemistry as well as cellular and molecular biology for non-life science students enrolling at the Master or PhD thesis level from various engineering disciplines. It reviews essential notions necessary for a training in biology-related engineering fields.

ENV-202: Microbiology for engineers

Le cours "Microbiologie pour l'ingénieur" couvre les processus microbiens principaux qui ont lieu dans l'environnement et dans des systèmes de traitement. Il présente les cycles des éléments qui sont catalysés par des microorganismes et qui ont un impact important sur la planète Terre.