Contributions to the quality control of two crops of economic importance : hops and yerba mate

Quality control of plants is essential and at the same time very challenging.In this thesis, studies involving quality issues of two plants used in the production of two popular beverages, hops (in beer) and Ilex paraguariensis (yerba mate) were undertaken. Hops are used as bittering agents and to increase foam stability in beer brewing. The compounds responsible for this are cis/trans isohumulones, produced by isomerisation of the 3 _-acids present in hops. To evaluate their individual effect, they had to be obtained in gram-scale amounts. For this, 3 methods based on the use of CPC (centrifugal partition chromatography) in combination with selective precipitation methods (DCHA) of trans-isomers were developed. Trans-isohumulones were found to precipitate selectively with _-cyclodextrin. Yerba mate is a popular tea-like beverage consumed in S America made from the leaves of Ilex paraguariensis , a species unique for its high caffeine content. The detection of adulterants i.e., cogeneric authoctonous Ilex species is vital for its quality control. The metabolomic profile of 11Ilex species was determined, resulting in the clear separation of all species. Additionally, arbutin was detected (0.5-10% dw) in several of the tested species but not in I. paraguariensis, though its presence had not been formerly reported.LEI Universiteit LeidenPlant science

Atrial fibrillation after gastrointestinal surgery: incidence and associated risk factors

BACKGROUND: Atrial fibrillation (AF) is a common dysrhythmia that can occur after major physiological stress including surgery (postoperative AF). There are few data on postoperative AF after abdominal surgery. We set out to define the incidence of de novo postoperative AF after abdominal surgery and associated risk factors. METHODS: The Patient History Integrated Data store administrative database was interrogated for patients aged ≥65 y undergoing abdominal surgery from April 2012 to April 2014. Patients with pre-existing AF were excluded. The primary outcome was diagnosis of AF. RESULTS: Two thousand nine hundred and sixty-seven cases were included of whom 187 developed postoperative AF within 90 d (6.3%). The rate of postoperative AF varied by operation and was highest in small bowel resection (17.2%) and lowest in biliary surgery (4.8%). Median time to detection of postoperative AF was 32 d. Patients who developed postoperative AF were significantly older than those who did not develop AF (median age 75.3 y versus 72.4 y, P < 0.01). Logistic regression modeling found increasing age (odds ratio [OR] 1.03 [confidence interval {CI} 1.01-1.06], hypertension OR 1.73 [CI 1.19-2.51]), congestive cardiac failure (OR 3.04 [CI 1.88-4.92], and vascular disease OR 2.29 [CI 1.39-3.37]) were predictive of the development of postoperative AF within 30 d. The area under the curve for this model was 0.733. CONCLUSIONS: Postoperative AF affects a significant number of patients after abdominal surgery. Demographics such as history of cardiovascular disease might aid prediction of postoperative AF. Postoperative AF is mostly identified after discharge, suggesting the need for postoperative screening

An integrated sequence stratigraphic, palaeoenvironmental, and chronostratigraphic analysis of the Tangahoe Formation, southern Taranaki coast, with implications for mid-Pliocene (c. 3.4–3.0 Ma) glacio-eustatic sea-level changes

Sediments of the mid-Pliocene (c. 3.4–3.0 Ma) Tangahoe Formation exposed in cliffs along the South Taranaki coastline of New Zealand comprise a 270 m thick, cyclothemic shallow-marine succession that has been gently warped into a north to south trending, low angle anticline. This study examines the sedimentologic, faunal, and petrographic characteristics of 10 Milankovitch-scale (6th order), shallow-marine depositional sequences exposed on the western limb of the anticline. The sequences are recognised on the basis of the cyclic vertical stacking of their constituent lithofacies, which are bound by sharp wave cut surfaces produced during transgressive shoreface erosion. Each sequence comprises three parts: (1) a 0.2–2 m thick, deepening upwards, basal suite of reworked bioclastic lag deposits (onlap shellbed) and/or an overlying matrix supported, molluscan shellbed of offshore shelf affinity (backlap shellbed); (2) a 5–20 m thick, gradually shoaling, aggradational siltstone succession; and (3) a 5–10 m thick, strongly progradational, well sorted “forced regressive” shoreline sandstone. The three-fold subdivision corresponds to transgressive, highstand, and regressive systems tracts (TSTs, HSTs, and RSTs) respectively, and represents deposition during a glacio-eustatic sea-level cycle. Lowstand systems tract sediments are not recorded because the outcrop is situated c. 100 km east of the contemporary shelf edge and was subaerially exposed at that time. Well developed, sharp- and gradational-based forced regressive sandstones contain a variety of storm-emplaced sedimentary structures, and represent the rapid and abrupt basinward translation of the shoreline on to a storm dominated, shallow shelf during eustatic sea-level fall. Increased supply of sediment from north-west South Island during “forced regression” is indicated from petrographic analyses of the heavy mineralogy of the sandstones. A chronology based on biostratigraphy and the correlation of a new magnetostratigraphy to the magnetic polarity timescale allows: (1) identification of the Mammoth (C2An.2r) and Kaena (C2An.1r) subchrons; (2) correlation of the coastal section to the Waipipian Stage; and (3) estimation of the age of the coastal section as 3.36–3.06 Ma. Qualitative assessment of foraminiferal census data and molluscan palaeoecology reveals cyclic changes in water depth from shelf to shoreline environments during the deposition of each sequence. Seven major cycles in water depth of between 20 and 50m have been correlated to individual 40 ka glacio-eustatic sea-level cycles on the marine oxygen isotope timescale. The coastal Tangahoe Formation provides a shallow-marine record of global glacio-eustasy prior to the development of significant ice sheets on Northern Hemisphere continents, and supports evidence from marine δ18O archives that changes in Antarctic ice volume were occurring during the Pliocene

Hamiltonian light-front field theory within an AdS/QCD basis

Non-perturbative Hamiltonian light-front quantum field theory presents opportunities and challenges that bridge particle physics and nuclear physics. Fundamental theories, such as Quantum Chromodynmamics (QCD) and Quantum Electrodynamics (QED) offer the promise of great predictive power spanning phenomena on all scales from the microscopic to cosmic scales, but new tools that do not rely exclusively on perturbation theory are required to make connection from one scale to the next. We outline recent theoretical and computational progress to build these bridges and provide illustrative results for nuclear structure and quantum field theory. As our framework we choose light-front gauge and a basis function representation with two-dimensional harmonic oscillator basis for transverse modes that corresponds with eigensolutions of the soft-wall AdS/QCD model obtained from light-front holography.Comment: To appear in the proceedings of Light-Cone 2009: Relativistic Hadronic and Particle Physics, July 8-13, 2009, Sao Jose dos Campos, Brazi

Application of natural deep eutectic solvents for the "green" extraction of vanillin from vanilla pods

Plant science

Application of natural deep eutectic solvents for the “green”extraction of vanillin from vanilla pods

Plant science

Rationale for UV-filtered clover fermions

We study the contributions Sigma_0 and Sigma_1, proportional to a^0 and a^1, to the fermion self-energy in Wilson's formulation of lattice QCD with UV-filtering in the fermion action. We derive results for m_{crit} and the renormalization factors Z_S, Z_P, Z_V, Z_A to 1-loop order in perturbation theory for several filtering recipes (APE, HYP, EXP, HEX), both with and without a clover term. The perturbative series is much better behaved with filtering, in particular tadpole resummation proves irrelevant. Our non-perturbative data for m_{crit} and Z_A/(Z_m*Z_P) show that the combination of filtering and clover improvement efficiently reduces the amount of chiral symmetry breaking -- we find residual masses am_{res}=O(10^{-2}).Comment: 25 pages, 4 figures; v2: typo in eqn. (37) fixed [agrees with published version

Why does fertilization reduce plant species diversity? Testing three competition-based hypotheses

1 Plant species diversity drops when fertilizer is added or productivity increases. To explain this, the total competition hypothesis predicts that competition above ground and below ground both become more important, leading to more competitive exclusion, whereas the light competition hypothesis predicts that a shift from below-ground to above-ground competition has a similar effect. The density hypothesis predicts that more above-ground competition leads to mortality of small individuals of all species, and thus a random loss of species from plots. 2 Fertilizer was added to old field plots to manipulate both below-ground and above-ground resources, while shadecloth was used to manipulate above-ground resources alone in tests of these hypotheses. 3 Fertilizer decreased both ramet density and species diversity, and the effect remained significant when density was added as a covariate. Density effects explained only a small part of the drop in diversity with fertilizer. 4 Shadecloth and fertilizer reduced light by the same amount, but only fertilizer reduced diversity. Light alone did not control diversity, as the light competition hypothesis would have predicted, but the combination of above-ground and below-ground competition caused competitive exclusion, consistent with the total competition hypothesis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75695/1/j.1365-2745.2001.00662.x.pd

Finite density QCD sum rules for nucleons

It is shown how the QCD sum rules can be applied for the investigation of the density dependence of the nucleon parameters. These characteristics can be expressed through the expectation values of QCD operators in nuclear matter. In certain approximations the expectation values are related to the observables. First applications of the approach reproduced some of the basic features of nuclear physics, providing also a new knowledge. The program of the future work is presented. The difficulties of the approach are discussed.Comment: 22 pages, Lecture at the International School on Nuclear Physics, Erice,200