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Possible Scenarios for Homochirality on Earth

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ISBN: 9783039217229 9783039217236 Year: Pages: 318 DOI: 10.3390/books978-3-03921-723-6 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General)
Added to DOAB on : 2019-12-09 11:49:16
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Abstract

In 1978, Fred Hoyle proposed that interstellar comets carrying several viruses landed on Earth as part of the panspermia hypotheses. With respect to life, the origin of homochirality on Earth has been the greatest mystery because life cannot exist without molecular asymmetry. Many scientists have proposed several possible hypotheses to answer this long-standing L-D question. Previously, Martin Gardner raised the question about mirror symmetry and broken mirror symmetry in terms of the homochirality question in his monographs (1964 and 1990). Possible scenarios for the L-D issue can be categorized into (i) Earth and exoterrestrial origins, (ii) by-chance and necessity mechanisms, and (iii) mirror-symmetrical and non-mirror-symmetrical forces as physical and chemical origins. These scenarios should involve further great amplification mechanisms, enabling a pure L- or D-world.

Keywords

chirogenesis --- enantiomorphism --- nepheline --- magmatic flow --- etch figures --- origin of life --- biological homochirality --- deracemization --- super-high-velocity impact --- plasma reactor --- absolute asymmetric synthesis --- amino acids --- origin of life --- amino acid handedness --- nucleus–molecular coupling --- chirality --- circularly polarized luminescence --- circular dichroism --- symmetry breaking --- parity violation --- weak neutral current --- tunneling --- Z0 boson --- homochirality --- precision measurement --- homochirality --- circularly polarized light --- asymmetric reaction --- polymer --- ?-strand --- hidden chirality --- two-fold helix --- multi-point approximation --- tilt-chirality --- high dimensional chirality --- spin polarized electrons --- homochirality --- magnetism --- prebiotic --- environmental chirality --- C1- and C2-symmetric catalysts --- chiral field (memory) --- racemic field --- Viedma ripening effect --- Wallach’s rule --- heat capacity --- metal-organic framework --- triethylenediamine (DABCO) molecules --- racemate --- Salam hypothesis --- homochirality --- parity violation --- neutrinos --- gravitation --- enantiomer self-disproportionation --- SDE --- achiral stationary phase --- homochiral and heterochiral aggregates --- chiral separation --- chirality --- genesis of life chirality --- asymmetric autocatalysis --- homochirality --- chirality --- asymmetric synthesis --- Soai reaction --- biological homochirality --- enantioselective reaction --- autocatalysis --- origin of life --- replicators --- bioorganic homochirality --- circularly polarized photon --- spin-polarized lepton --- parity violation in the weak interaction --- symmetry breaking --- assemblies --- supramolecular chirality --- homochirality --- self-assembly --- vortex --- lipid --- supramolecular assembly --- symmetry breaking --- homochirality

Cocoa, Chocolate and Human Health

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ISBN: 9783039285884 / 9783039285891 Year: Pages: 288 DOI: 10.3390/books978-3-03928-589-1 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Biology --- Nutrition and Food Sciences
Added to DOAB on : 2020-06-09 16:38:57
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This book entitled “Cocoa, Chocolate, and Human Health” presents the most recent findings about cocoa and health in 14 peer-reviewed chapters including nine original contributions and five reviews from cocoa experts around the world. Bioavailability and metabolism of the main cocoa polyphenols, i.e., the flavanols like epicatechin, are presented including metabolites like valerolactones that are formed by the gut microbiome. Many studies, including intervention studies or epidemiological observations, do not focus on single compounds, but on cocoa as a whole. This proves the effectiveness of cocoa as a functional food. A positive influence of cocoa on hearing problems, exercise performance, and metabolic syndrome is discussed with mixed results; the results about exercise performance are contradictive. Evidence shows that cocoa flavanols may modulate some risk factors related to metabolic syndrome such as hypertension and disorders in glucose and lipid metabolism. However, several cardiometabolic parameters in type 2 diabetics were not affected by a flavanol-rich cocoa powder as simultaneous treatment with pharmaceuticals might have negated the effect of cocoa. The putative health-promoting components of cocoa are altered during processing like fermentation, drying, and roasting of cocoa beans. Chocolate, the most popular cocoa product, shows remarkable losses in polyphenols and vitamin E during 18 months of storage.

Keywords

type 2 diabetes --- flavanol-rich cocoa --- blood pressure --- glucose metabolism --- lipid status --- type 2 diabetes --- flavanol-rich cocoa --- postprandial --- meal --- glucose metabolism --- lipids --- blood pressure --- cocoa processing --- cocoa proteins --- classification --- extraction and characterization methods --- fermentation-related enzymes --- bioactive peptides --- heath potentials --- protein–phenol interactions --- chocolate --- hearing loss --- tinnitus --- cohort study --- cocoa --- bioactive compounds --- flavanols bioavailability --- anti-inflammatory properties --- metabolic syndrome --- oxidative stress --- cocoa by-product --- functional food --- polyphenols --- ?-glucosidase inhibition --- antidiabetic capacity --- antioxidant capacity --- methylxanthines --- fermentation --- functional volatile compounds --- starter culture --- yeast --- roasting --- chocolate --- cocoa beans --- theobromine --- cacao --- working memory --- behavior --- CaMKII --- CREB --- BDNF --- cocoa --- oligopeptides --- simulated gastrointestinal digestion --- angiotensin-converting enzyme (ACE) inhibitory activity --- cocoa --- chocolate --- metabolites --- biomarkers --- metabolomics --- urine --- plasma --- procyanidins --- methylxanthines --- polyphenols --- flavanols --- soluble cocoa products --- bioavailability --- human --- plasma nutrikinetics --- liquid chromatography coupled to electrospray ionisation and quadrupole time-of-flight mass spectrometry (LC-ESI-QToF-MS) --- colonic bacteria --- athlete --- cocoa --- chocolate --- exercise performance --- oxidative stress --- performance --- physical exercise --- polyphenol --- skeletal muscle --- inflammation --- Italian chocolate --- quality --- cocoa-based ingredients --- monitoring --- nutrition --- cocoa --- flavan-3-ol stereoisomers --- (?)-epicatechin --- (+)-catechin --- (?)-catechin --- plasma appearance --- chiral separation --- pharmacokinetics --- one-compartment model --- n/a

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