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Advances in Cholesteric Liquid Crystals

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ISBN: 9783039282289 9783039282296 Year: Pages: 122 DOI: 10.3390/books978-3-03928-229-6 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Chemistry (General) --- Science (General)
Added to DOAB on : 2020-04-07 23:07:08
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With their helical structure, cholesteric liquid crystals figure prominently in liquid crystal science. The selective reflection of light is their flagship property, and they offer a myriad of applications as advanced optical materials with multiscale properties. The cholesteric structure is also a ubiquitous design in the animal and plant kingdoms. This book contains eight contributions on fundamental investigations about defects, textures and structures of cholesteric materials, and experimental studies aimed at applications such as temperature sensors, head-up displays for improving automobile driving safety, or smart windows.

Biological Crystallization

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ISBN: 9783039214037 9783039214044 Year: Pages: 184 DOI: 10.3390/books978-3-03921-404-4 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Biology
Added to DOAB on : 2019-12-09 11:49:15
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For at least six hundred million years, life has been a fascinating laboratory of crystallization, referred to as biomineralization. During this huge lapse of time, many organisms from diverse phyla have developed the capability to precipitate various types of minerals, exploring distinctive pathways for building sophisticated structural architectures for different purposes. The Darwinian exploration was performed by trial and error, but the success in terms of complexity and efficiency is evident. Understanding the strategies that those organisms employ for regulating the nucleation, growth, and assembly of nanocrystals to build these sophisticated devices is an intellectual challenge and a source of inspiration in fields as diverse as materials science, nanotechnology, and biomedicine. However, “Biological Crystallization” is a broader topic that includes biomineralization, but also the laboratory crystallization of biological compounds such as macromolecules, carbohydrates, or lipids, and the synthesis and fabrication of biomimetic materials by different routes. This Special Issue collects 15 contributions ranging from biological and biomimetic crystallization of calcium carbonate, calcium phosphate, and silica-carbonate self-assembled materials to the crystallization of biological macromolecules. Special attention has been paid to the fundamental phenomena of crystallization (nucleation and growth), and the applications of the crystals in biomedicine, environment, and materials science.

Keywords

polymyxin resistance --- colistin resistance --- MCR-1 --- protein crystal nucleation --- thermodynamic and energetic approach --- protein ‘affinity’ to water --- solubility --- balance between crystal bond energy and destructive surface energies --- supersaturation dependence of the crystal nucleus size --- ependymin (EPN) --- ependymin-related protein (EPDR) --- mammalian ependymin-related protein (MERP) --- Campylobacter consisus --- Crohn’s disease --- circular dichroism --- protein crystallization --- Csep1p --- protein crystallization --- biochemical aspects of the protein crystal nucleation --- classical and two-step crystal nucleation mechanisms --- bond selection during protein crystallization --- equilibration between crystal bond and destructive energies --- protein crystal nucleation in pores --- crystallization in solution flow --- crystallization --- microseed matrix screening --- seeding --- optimization --- human carbonic anhydrase IX --- neutron protein crystallography --- microbially induced calcite precipitation (MICP) --- heavy metals --- wastewater treatment --- bioprecipitation --- calcium carbonate --- drug discovery --- education --- crystallization --- crystallography --- nucleation --- micro-crystals --- agarose --- ferritin --- lysozyme --- proteinase k --- insulin --- calcium carbonate --- {00.1} calcite --- lithium ions --- ultrasonic irradiation --- vaterite transformation --- adsorption --- calcein --- crystal violet --- dyes --- diffusion --- H3O+ --- reductants --- color change --- gradients --- biomorphs --- barium carbonate --- silica --- PCDA --- pyrrole --- droplet array --- crystal growth --- calcium carbonate --- high-throughput --- biomimetic crystallization --- biomineralization --- polyacrylic acid --- Cry protein crystals --- metallothioneins --- bioremediation --- heavy metal contamination --- nanoapatites --- graphene --- crystallization --- nanocomposites --- lysozyme --- L-tryptophan --- N-acetyl-D-glucosamine --- chitosan --- MTT assay --- GTL-16 cells --- Haloalkane dehalogenase --- halide-binding site --- random microseeding --- biomineralization --- biomimetic materials --- biomorphs --- calcium carbonate --- nanoapatites --- nucleation --- growth --- crystallization of macromolecules --- bioremediation --- materials science --- biomedicine

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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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

Biomimetic Radical Chemistry and Applications

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ISBN: 9783039283927 9783039283934 Year: Pages: 300 DOI: 10.3390/books978-3-03928-393-4 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Biology --- Science (General)
Added to DOAB on : 2020-04-07 23:07:09
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The enormous importance of free radical chemistry for a variety of biological events, including ageing and inflammation, has attracted a strong interest in understanding the related mechanistic steps at the molecular level. Modelling the free radical chemical reactivity of biological systems is an important research area. When studying free-radical-based chemical mechanisms, biomimetic chemistry and the design of established biomimetic models come into play to perform experiments in a controlled environment that is suitably designed to be in strict connection with cellular conditions. This Special Issue gives the reader a wide overview of biomimetic radical chemistry, where molecular mechanisms have been defined and molecular libraries of products are developed to also be used as traces for the discovery of some relevant biological processes. Several subjects are presented, with 12 articles and 6 reviews written by specialists in the fields of DNA, proteins, lipids, biotechnological applications, and bioinspired synthesis, having “free radicals” as a common denominator.

Keywords

type 2 diabetes --- glycogen phosphorylase --- anomeric spironucleosides --- 1,6-dioxa-4-azaspiro[4.5]decane --- [1,5]-radical translocation --- DNA --- guanine quadruplexes --- radicals --- electron holes --- oxidative damage --- photo-ionization --- time-resolved spectroscopy --- inhomogeneous reactions --- radiosensitizers --- stationary radiolysis --- pulse radiolysis --- modified nucleosides --- cellular response --- liposomal somatostatin --- retarded delivery --- free radicals --- isomerization --- trans lipid --- peroxidation --- photolysis --- laser flash photolysis --- ?-radiolysis --- singlet oxygen --- nucleosides --- free radicals --- reaction mechanism --- catalase activity --- iron(IV)-oxo --- hydrogen peroxide --- oxidation --- kinetic studies --- gold nanoparticles --- albumin --- EPR spectroscopy --- Raman spectroscopy --- circular dichroism --- beta cells --- diabetes --- confocal microscopy --- lipidomics --- membrane fluidity maps --- cell micropolarity maps --- DNA damage --- 5?,8-cyclopurines --- 8-oxo-dG --- free radicals --- pulse radiolysis --- gamma radiolysis --- Fenton reaction --- oligonucleotides --- oxidative DNA damage --- DNA replication stress --- replication fork stalling --- genomic and epigenomic instability --- DNA methylation --- histone modifications --- miRNAs --- iron porphyrin --- heme --- ATRPase --- iron-mediated ATRP --- bio-mimicking catalyst --- biomimetic radical reaction --- bioinspired chemical catalysis --- protein labeling --- DNA oxidation --- DNA hole transfer --- DNA --- quantum dynamics --- electron transfer --- charge transfer --- radical reaction --- azidoalkylation --- carboazidation --- sulfones --- azides --- Julia–Kocienski olefination --- DNA damage --- copper --- chemical nuclease --- intercalation --- free radical oxidation --- protein stability --- therapeutic proteins --- thiyl radicals --- oxidation --- fragmentation --- cross-link --- 2-thiouracil --- radiosensitizers --- ?OH and ?N3 radicals --- 2c-3e S?S-bonded intermediates --- pulse radiolysis --- TD-DFT methods --- thiobases --- nucleobase derivatives --- reactive aldehydes --- hydroxynonenal --- oxononenal --- free fatty acids --- mitochondrial uncoupling protein --- lipid bilayer membranes

Natural Products and Drug Discovery

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ISBN: 9783039287468 / 9783039287475 Year: Pages: 392 DOI: 10.3390/books978-3-03928-747-5 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Biology
Added to DOAB on : 2020-06-09 16:38:57
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Natural products hold a prominent position in the current discovery and development of drugs and have diverse indications for both human and animal health. Plants, in particular, play a leading role as a source of specialized metabolites with medical effects. Other organisms, such as marine and terrestrial animals and microorganisms, produce very important drug candidate molecules. Specialized metabolites from these varied natural sources can be used directly as bioactive compounds or drug precursors. In addition, due to their broad chemical diversity, they can act as drug prototypes and/or be used as pharmacological tools for different targets. Some examples of natural metabolites that have been developed into useful medical drug are cardiotonic digoxin from Digitalis sp., antimalarial artemisinin from Artemisia annua, anti-cancer taxol from Taxus sp., or podophyllotoxin from Podophyllum peltatum, which served as a synthetic model for the anti-cancer etoposide. The study of natural products is still attracting great scientific attention and their current importance, as a valuable lead for drug discovery, is undebatable. I cordially invite authors to contribute original articles, as well as survey articles, that give the readers of Molecules **MOLECULES NEEDS TO BE ITALICIZED** updated and new perspectives on natural products in drug discovery, including but not limited to natural sources, identification and separation of bioactive phytochemicals, standardization, new biological targets, pre-clinical and clinical trials, pharmacological effects/side effects, and bioassays.

Keywords

cytotoxicity-guided --- phenolic derivatives --- Dryopteris fragrans --- chemical derivatization --- immuno-regulation activity --- Imperata cylindrica --- HPLC --- ESI-MS/MS --- growth inhibitory activity --- cancer --- cardamonin --- antinociceptive --- TRPV1 --- glutamate --- opioid --- siphonous green algae --- sulfated coumarins --- Dasycladus vermicularis --- isolation and quantification --- Orobanche s.l. --- Orobanchaceae --- Lamiales --- natural products --- secondary metabolites --- phenylpropanoid glycosides --- phenylethanoid glycosides --- bioactivities of natural products --- chemosystematics --- FSE --- T2DM --- GLUT4 --- Ca2+ --- L6 cell --- marine peptides --- proliferation --- migration --- angiogenesis --- zebrafish --- antioxidant activity --- flavonoids --- isoflavones --- phenolics --- proanthocyanidins --- Trifolium --- Leea indica --- HPLC-ESI-microTOF-Q-MS/MS --- phenolics --- dihydrochalcones --- Humulus lupulus --- prenylated phenolic compounds --- antimicrobial agents --- methicillin-resistant Staphylococcus aureus --- Leishmania mexicana mexicana --- Trypanosoma brucei brucei --- Astragalus boeticus L. --- spectroscopic analysis --- cytotoxic activity --- human colon cancer cell lines --- acetylated astragalosides --- Fabaceae --- aging --- cancer --- cardiovascular disease --- dementia --- diabetes --- inflammation --- oxidative stress --- Harpagophytum procumbens --- devil’s claw --- harpagoside --- spagyric tincture --- antioxidant activity --- Cleistocalyx operculatus --- 2?,4?-dihydroxy-6?-methoxy-3?,5?-dimethylchalcone (DMC) --- pPancreatic cancer --- PANC-1 --- ACE inhibitory peptide --- antihypertensive --- bioactive peptides --- hypertension --- marine resources --- terpenes --- terpenoids --- antimicrobial resistance --- synergy --- Phyllanthus orbicularis --- C-glycoside --- flavonoid --- natural products --- traditional medicine --- Cuba --- Phyllanthus chamacristoides --- chromatography --- mass spectrometry --- NMR --- circular dichroism --- stereochemistry --- Fideloside --- cytokines --- anti-inflammatory activity --- metabolomics --- multivariate data analysis --- molecular network --- Bacopa monnieri --- LC-MS --- diabetic neuropathy --- neuropathic pain --- glucosinolates --- Eruca sativa --- glucoerucin --- H2S --- Kv7 potassium channels --- artemisinin --- Physcomitrella patens --- sesquiterpenoids --- malaria --- biotechnology --- ketamine --- psychosis --- cerebellum --- celastrol --- oxidative stress --- NADPH oxidases --- n/a

Polymeric Systems as Antimicrobial or Antifouling Agents

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ISBN: 9783039284566 / 9783039284573 Year: Pages: 400 DOI: 10.3390/books978-3-03928-457-3 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Social Sciences --- Sociology
Added to DOAB on : 2020-06-09 16:38:57
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The rapid increase in the emergence of antibiotic-resistant bacterial strains, combined with a dwindling rate of discovery of novel antibiotic molecules, has created an alarming issue worldwide. Although the occurrence of resistance in microbes is a natural process, the overuse of antibiotics is known to increase the rate of resistance evolution. Under antibiotic treatment, susceptible bacteria inevitably die, while resistant microorganisms proliferate under reduced competition. Therefore, the out-of-control use of antibiotics eliminates drug-susceptible species that would naturally limit the expansion of resistant species. In addition, the ability of many microbial species to grow as a biofilm has further complicated the treatment of infections with conventional antibiotics. A number of corrective measures are currently being explored to reverse or slow antibiotic resistance evolution, Among which one of the most promising solutions is the development of polymer-based antimicrobial compounds. In this Special Issue, different polymer systems able to prevent or treat biofilm formation, including cationic polymers, antibacterial peptide-mimetic polymers, polymers or composites able to load and release bioactive molecules, and antifouling polymers able to repel microbes by physical or chemical mechanisms are reported. Their applications in the design and fabrication of medical devices, in food packaging, and as drug carriers is investigated.

Keywords

cationic polymers --- imidization --- quaternization --- antimicrobial properties --- hemolytic activity --- coatings from nanoparticles --- biocompatible polymer --- antimicrobial polymer --- dynamic light scattering --- coatings wettability --- microbicidal coatings --- bacteria viability --- bactericidal coatings --- Escherichia coli --- Staphylococcus aureus --- Acinetobacter baumannii --- multidrug-resistant --- antimicrobial peptide --- antibiofilm activity --- physiological salt --- biofilm --- anti-biofilm surface --- surface functionalization --- ?-chymotrypsin --- proteinase --- antimicrobial polymers --- quaternary ammonium --- 2-hydroxyethyl methacrylate --- thermal stability --- polymers --- antibacterial --- drug delivery --- periodontitis --- periodontal biofilms --- polyamide 11 --- antibacterial --- polymeric biocide --- thermal stability --- biofilm --- antifouling --- copper paint --- additives --- biofilm --- lipopeptides --- biofilm --- persister cells --- ocular infections --- biofilm on contact lenses --- cuprous oxide nanoparticles --- linear low-density polyethylene --- composites --- adhesives --- antibacterial activity --- water disinfection --- active packaging --- antimicrobial peptides --- food shelf-life --- foodborne pathogens --- plastic materials --- antibacterial peptides --- halictine --- circular dichroism --- fluorescence --- infrared spectroscopy --- segmented polyurethanes --- polyethylene glycol --- microbial biofilm --- antifouling materials --- medical device-related infections --- wound dressings --- additive manufacturing --- antibacterial polymers --- biocompatible systems --- drug delivery systems --- 3D printing --- amorphous materials --- ordered mesoporous silica --- sol-gel preparation --- drug carrier --- multifunctional hybrid systems --- olive mill wastewater --- antibacterial properties --- layered double hydroxides --- bionanocomposites --- acrylates --- antibacterial activity --- copolymerization --- polymeric films --- polymerizable quaternary ammonium salts --- quaternary ammonium salts --- UV-induced polymerization --- antimicrobial resistance --- antimicrobial polymers --- ESKAPE pathogens --- anti-biofilm surfaces --- polymeric surfaces --- biofilm methods --- biofilm analysis --- biofilm devices --- n/a

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