28 research outputs found
Ground State Energy of Massive Scalar Field Inside a Spherical Region in the Global Monopole Background
Using the zeta function regularization method we calculate the ground state
energy of scalar massive field inside a spherical region in the space-time of a
point-like global monopole. Two cases are investigated: (i) We calculate the
Casimir energy inside a sphere of radius and make an analytical analysis
about it. We observe that this energy may be positive or negative depending on
metric coefficient and non-conformal coupling . In the limit
we found a zero result. (ii) In the second model we surround the
monopole by additional sphere of radius and consider scalar field
confined in the region between these two spheres. In the latter, the ground
state energy presents an additional contribution due to boundary at which
is divergent for small radius. Additional comments about renormalization are
considered.Comment: 30 pages and 2 figures. LATEX fil
Real-Time PCR Assays for the Quantitation of rDNA from Apricot and Other Plant Species in Marzipan
Marzipan
or marzipan raw paste is a typical German sweet which
is consumed directly or is used as an ingredient in the bakery industry/confectionery
(e.g., in stollen) and as filling for chocolate candies. Almonds (blanched
and pealed) and sugar are the only ingredients for marzipan production
according to German food guidelines. Especially for the confectionery
industry, the use of persipan, which contains apricot or peach kernels
instead of almonds, is preferred due to its stronger aroma. In most
of the companies, both raw pastes are produced, in most cases on the
same production line, running the risk of an unintended cross contamination.
Additionally, due to high almond market values, dilutions of marzipan
with cheaper seeds may occur. Especially in the case of apricot and
almond, the close relationship of both species is a challenge for
the analysis. DNA based methods for the qualitative detection of apricot,
peach, pea, bean, lupine, soy, cashew, pistachio, and chickpea in
marzipan have recently been published. In this study, different quantitation
strategies on the basis of real-time PCR have been evaluated and a
relative quantitation method with a reference amplification product
was shown to give the best results. As the real-time PCR is based
on the high copy rDNA-cluster, even contaminations <1% can be reliably
quantitated
Die Italienischen Hausmöbel der Renaissance
Document original a: Centre de Documentació del Museu de Disseny de Barcelona (topogràfic : B-XX-156). Data aproximada: [1902]Digitalitzat per Artyplan per encàrrec del Centre de Documentació del Museu del Disseny de Barcelon
Marzipan: Polymerase Chain Reaction-Driven Methods for Authenticity Control
According to German food guidelines, almonds are the only oilseed ingredient allowed for the production of marzipan. Persipan is a marzipan surrogate in which the almonds are replaced by apricot or peach kernels. Cross-contamination of marzipan products with persipan may occur if both products are produced using the same production line. Adulterations or dilutions, respectively, of marzipan with other plant-derived products, for example, lupine or pea, have also been found. Almond and apricot plants are closely related. Consequently, classical analytical methods for the identification/differentiation often fail or are not sensitive enough to quantify apricot concentrations below 1%. Polymerase chain reaction (PCR)-based methods have been shown to enable the differentiation of closely related plant species in the past. These methods are characterized by high specificity and low detection limits. Isolation methods were developed and evaluated especially with respect to the matrix marzipan in terms of yield, purity, integrity, and amplificability of the isolated DNA. For the reliable detection of apricot, peach, pea, bean, lupine, soy, cashew, pistachio, and chickpea, qualitative standard and duplex PCR methods were developed and established. The applicability of these methods was tested by cross-reaction studies and analysis of spiked raw pastes. Contaminations at the level of 0.1% could be detected
Kinetics of Strain-Induced Crystallization in Natural Rubber Studied by WAXD: Dynamic and Impact Tensile Experiments
The time-dependence of strain-induced crystallization
in cross-linked
natural rubber was studied using synchrotron wide-angle X-ray diffraction
(WAXD) with an unprecedented time resolution in the ms range. In-situ
dynamic mechanical tests and tensile impact tests were carried out.
In tensile impact tests, consisting of a strain step within less than
10 ms, it was found that roughly half of the crystallization process
was complete within less than 5 ms, provided the strain is large enough.
Afterward, crystallization proceeded on a time scale of a few seconds.
This implies that under dynamic loading at frequencies which are typically
encountered in the application of rubbers, the degree of crystallinity
is considerably lower than under equilibrium conditions. This was
directly confirmed by in situ dynamic cyclic experiments at a frequency
of approximately 1 Hz. Since crystallization is a major factor contributing
to the outstanding mechanical properties of natural rubber, these
findings can aid in the interpretation and prediction of the frequency-dependence
of mechanical properties
Determination of Urinary Metabolites of the Emerging UV Filter Octocrylene by Online-SPE-LC-MS/MS
Octocrylene
(OC) is an emerging UV filter, which is used in the
majority of sunscreens as well as other personal care products (PCP)
and consumer products. Its presence in various environmental matrices
has been reported. However, information on the internal OC exposure
in humans is not available, due to the lack of appropriate biomarkers
of exposure and analytical methods. Here, we describe a rugged, precise,
and accurate analytical method for the determination of three OC metabolites
(ester hydrolysis and alkyl chain oxidation products) in human urine
by stable isotope dilution analysis. Urine samples are incubated with
β-glucuronidase (<i>E. coli</i> K12) and then analyzed
by liquid chromatography-electrospray ionization-triple quadrupole-tandem
mass spectrometry with online turbulent flow chromatography for sample
cleanup and analyte enrichment (online-SPE-LC-MS/MS). Syntheses of
analytical standards, including deuterium-labeled internal standards,
are also described. In a pilot study, we investigated the applicability
of the metabolites as biomarkers of exposure in urine samples from
the general population (<i>n</i> = 35). OC metabolites were
detected in 91% of the samples, with the highest concentrations for
three individuals having used sunscreen within 5 days prior to sample
collection. We will apply the method in future human biomonitoring
studies for OC exposure and risk assessment
Structural Changes of Gluten/Glycerol Plastics under Dry and Moist Conditions and during Tensile Tests
The
structures of wheat gluten-based materials are greatly influenced
by plasticizer content, moisture content, and external mechanical
loading. In this study, the effects of moisture on the structure of
wheat gluten (WG) plasticized by glycerol were investigated by using
in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering
(WAXS), mechanical tensile testing, and thermal analyses. The materials
were processed with additives of ammonium hydroxide/salicylic acid
or urea and conditioned at 0, 50, and 100% relative humidity (RH).
In general, water showed similar effects on the WG structure and mechanical
properties regardless of the type of additive. It was observed that
the known hexagonal close-packed (HCP) structure in WG was present
mainly under moist conditions and swelled with an increase in water
content. The absorbed water molecules hydrated the protein chains
at 50% RH and further led to the formation of a separate water/glycerol
phase at 100% RH. An interesting feature was observed by in situ SAXS
during tensile deformation; both the HCP structure and other protein
aggregates packed more densely in both the tensile and transverse
directions. It is interpreted as follows: “randomly oriented”
chains were drawn out and stretched in the tensile direction, which
squeezes the self-assembled structures together, similar to “tightening
a knot”
Combustion of Hydrotreated Vegetable Oil and Jatropha Methyl Ester in a Heavy Duty Engine: Emissions and Bacterial Mutagenicity
Research on renewable fuels has to
assess possible adverse health
and ecological risks as well as conflicts with global food supply.
This investigation compares the two newly developed biogenic diesel
fuels hydrotreated vegetable oil (HVO) and jatropha methyl ester (JME)
with fossil diesel fuel (DF) and rapeseed methyl ester (RME) for their
emissions and bacterial mutagenic effects. Samples of exhaust constituents
were compared after combustion in a Euro III heavy duty diesel engine.
Regulated emissions were analyzed as well as particle size and number
distributions, carbonyls, polycyclic aromatic hydrocarbons (PAHs),
and bacterial mutagenicity of the exhausts. Combustion of RME and
JME resulted in lower particulate matter (PM) compared to DF and HVO.
Particle numbers were about 1 order of magnitude lower for RME and
JME. However, nitrogen oxides (NO<sub>X</sub>) of RME and JME exceeded
the Euro III limit value of 5.0 g/kWh, while HVO combustion produced
the smallest amount of NO<sub>X</sub>. RME produced the lowest emissions
of hydrocarbons (HC) and carbon monoxide (CO) followed by JME. Formaldehyde,
acetaldehyde, acrolein, and several other carbonyls were found in
the emissions of all investigated fuels. PAH emissions and mutagenicity
of the exhausts were generally low, with HVO revealing the smallest
number of mutations and lowest PAH emissions. Each fuel showed certain
advantages or disadvantages. As proven before, both biodiesel fuels
produced increased NO<sub>X</sub> emissions compared to DF. HVO showed
significant toxicological advantages over all other fuels. Since jatropha
oil is nonedible and grows in arid regions, JME may help to avoid
conflicts with the food supply worldwide. Hydrogenated jatropha oil
should now be investigated if it combines the benefits of both new
fuels
A novel translational control mechanism involving RNA structures within coding sequences
The impact of RNA structures in coding sequences (CDS) within mRNAs is poorly understood. Here, we identify a novel and highly conserved mechanism of translational control involving RNA structures within coding sequences and the DEAD-box helicase Dhh1. Using yeast genetics and genome-wide ribosome profiling analyses, we show that this mechanism, initially derived from studies of the Brome Mosaic virus RNA genome, extends to yeast and human mRNAs highly enriched in membrane and secreted proteins. All Dhh1-dependent mRNAs, viral and cellular, share key common features. First, they contain long and highly structured CDSs, including a region located around nucleotide 70 after the translation initiation site; second, they are directly bound by Dhh1 with a specific binding distribution; and third, complementary experimental approaches suggest that they are activated by Dhh1 at the translation initiation step. Our results show that ribosome translocation is not the only unwinding force of CDS and uncover a novel layer of translational control that involves RNA helicases and RNA folding within CDS providing novel opportunities for regulation of membrane and secretome proteins.This work was supported by the Spanish Ministry of Economy and Competitiveness through grant BFU 2013-44629-R and the “Maria de Maeztu” Programme for Units of Excellence in R&D (MDM-2014-0370). J.J. was supported by the grant 2012FI_B00574 from the Generalitat de Catalunya. This work was also supported by the Deutsche Forschungsgemeinschaft/n(SFB860 to M.T.B.), the Alexander von Humboldt foundation/n(to K.E.S. and M.T.B.), the Max Planck Society (to S.A.L.),/nthe Spanish Ministerio de Economia y Competividad/ISCIIIFEDER/n(PI14/00125 to P.N.), and the Generalitat de Catalunya/n(2014/SGR/143 to P.N.