43,948 research outputs found
Structural Rearrangement Followed by Entrapment of Subnanometer Building Blocks of Iron Oxyhydroxide in Aqueous Iron Chloride Solutions
No full textIron oxyhydroxide, a natural nanophase of iron found in the environment, plays a crucial role in regulating surface and groundwater composition. Recent research proposes that within the nonclassical prenucleation cluster growth model, subnanometer-sized clusters (olation clusters/Fe-13 delta-Keggin oxolation clusters) might act as the prenucleation clusters (PNCs) of ferrihydrite or iron oxyhydroxide solid phase. However, these clusters are difficult to characterize as they are only observable momentarily in low-pH, high-Fe concentration solutions before agglomerating into extended solids, keeping the controversy over the true nature of the PNCs alive. In this study, we introduce large quantities of zinc acetate salt (ZA) into iron chloride solutions at the olation-oxolation boundary (3.6 mM Fe3+ at pH similar to 2.6). Remarkably, this manipulation is found to alter the structural arrangement of these subnanometer clusters before blocking them in isolation for hours, even at pH 6, where extended iron oxyhydroxide phases typically precipitate. On the other hand, controlled addition of ZA allows partial unblocking, leading to anisotropic agglomeration into cylindrical rod-like structures. Experimental techniques such as synchrotron-based small-angle X-ray scattering, X-ray absorption spectroscopy, high-resolution transmission electron microscopy (TEM), and cryo-TEM, along with density functional theory (DFT) calculations, reveal the nature of the structural rearrangement and the crucial role of Zn2+ ions in cluster stabilization
Dinuclear cobalt(II) complexes of Schiff-base compartmental ligands: Syntheses, crystal structure and bio-relevant catalytic activities
No full textThree dicobalt(II) complexes, namely [Co2(L1H)(H2O)2(OAc)2](OAc)2 (1), [Co2(L2)(H2O)2(OAc)2](OAc) (2)
and [Co2(L3)(H2O)2(OAc)2](OAc) (3) of the p-cresol based ‘‘end-off’’ compartmental ligands 2,6-bis(R-iminomethyl)-
4-methyl-phenolato, where R = N-ethylpiperazine for L1, 2-ethylpyridine for L2 and N-ethylpiperidine
for L3, have been synthesized and characterized by common physicochemical techniques, and in
the case of complex 1 also by single crystal X-ray diffraction analysis. All the complexes show excellent
catecholase-like activity, monitored not only with 3,5-di-tert-butylcatechol but also with tetrachlorocatechol,
a substrate reluctant to be oxidized. To the best of our knowledge, to date no cobalt complex has
been found in the literature to manifest such activity. The complexes are observed to interact efficiently
with CT-DNA and on incubation (employing plasmid pTZ57/R/T DNA) they exhibit concentration dependent
DNA cleavage activity. The mechanisms related to the DNA cleavage and catecholase-like activities
have been investigated. The cytotoxicity of the complexes has also been examined through an MTT assay
Dinuclear zinc(II) complexes with compartmental ligands: syntheses, structures, and bioactivities as artificial nuclease
No full textSeminário sobre aquacultura 14 a 16 de dezembro de 1983
No full textA necessidade de desenvolver a aquacultura em Portugal obriga à escolha das espécies mais indicadas para tal finalidade. A propósito o autor chama a atenção para as graves consequências que podem advir das introduções e/ou transferências de animais aquáticos, quer para as espécies locais e meio ambiente, como para a para a saúde pública.Concerning the need to choose the most convenient species to cultivate in order to implement aquaculture in Portugal, the author draws the attention to the deleterious consequences of introductions and transfers of aquatic animals.Caixa Geral de Depósito
Curious Behavior of Fe3+-As3+ Chemical Interactions and Nucleation of Clusters in Aqueous Medium
No full textThis study reveals the existence of FeAs clusters (primarilyFe(4)As(4), having a tooeleite-like local structure)in a nearly groundwater-like situation, i.e., far from the acid minedrainage condition, consequently entrapping As3+ from suchsolutions within tooeleite-like cages.The simultaneous presence of Fe3+ and As3+ ions in groundwater (higher ppb or lowerppm level concentrationsat circumneutral pH) as well as in acid mine drainages (AMDs)/industrialwastewater (up to few thousand ppm concentration at strongly acidicpH) are quite common. Therefore, understanding the chemical interactionsprevalent between Fe3+ and As3+ ions in aqueousmedium leading to nucleation of ionic clusters/solids, followed byaggregation and growth, is of great environmental significance. Inthe present work, we attempt to probe the nucleation process of Fe3+-As3+ clusters in solutions of various concentrationsand pHs (from AMD to groundwater-like) using a combination of experimentaland theoretical techniques. Interestingly, our study reveals nucleationof primary FeAs clusters in nearly all of them independent of concentrationor pH. Theoretical studies employed density functional theory (DFT)to predict the primary clusters as stable Fe4As4 units. The surprising resemblance of these clusters with known Fe3+-As3+ minerals at the local level was observedexperimentally, which provides an important clue about solid-phasegrowth from a range of Fe3+-As3+ solutions.Our experimental findings are further supported by a stepwise reactionmechanism established from detailed DFT studies
Role of ligand backbone of tridentate Schiff-base on complex nuclearity and bio-relevant catalytic activities of zinc(II) complexes: Experimental and theoretical investigations
No full textReaction of ZnII-acetate with two N, N, O-donor Schiff-base ligands, HL1 {4-Chloro-2-[(2-morpholin-4-ylethylimino)-
methyl]-phenol} and HL2 {4-Chloro-2-[(3-morpholin-4-yl-propylimino)-methyl]-phenol},
which are formed in situ via condensation of 5-chlorosalicylaldehyde and N-(2-aminoethyl/propyl)morpholine,
produce one tri- and one mononuclear species, Zn3L1(OAc)4 (1) and ZnL2(OAc) (2). The hypothetical
ZnL1(OAc) and Zn3L2(OAc)4 are energetically unfavorable by 9.2 and 5.1 kcal/mol, in compare with
their respective real counterparts 1 and 2 evidenced from DFT calculations. Both 1 and 2 catalyze the
hydrolytic cleavage of phosphoester bond of (4-nitrophenyl) phosphate where 1 shows higher activity
than that of 2. The proposed mechanistic pathways of phosphatase activity of 1 and 2 and the higher efficiency
of the latter have been rationalized by DFT study. DNA cleavage activities have been investigated
using supercoiled pET28a plasmid DNA where both the complexes show dose dependent DNA cleavage
activity with varying degree. Complex 1 shows excellent breakage activity even at a concentration of
20 lM. However, in both cases hydroxyl radical pathway is most probably operative in DNA cleavage
activity
Redox-Responsive Nanocapsules for the Spatiotemporal Release of Miltefosine in Lysosome: Protection against Leishmania
No full textLeishmaniasis, a vector-borne disease, is caused by intracellular parasite Leishmania donovani. Unlike most intracellular pathogens, Leishmania donovani are lodged in parasitophorous vacuoles and replicate within the phagolysosomes in macrophages. Effective vaccines against this disease are still under development, while the efficacy of the available drugs is being questioned owing to the toxicity for nonspecific distribution in human physiology and the reported drug-resistance developed by Leishmania donovani. Thus, a stimuli-responsive nanocarrier that allows specific localization and release of the drug in the lysosome has been highly sought after for addressing two crucial issues, lower drug toxicity and a higher drug efficacy. We report here a unique lysosome targeting polymeric nanocapsules, formed via inverse mini-emulsion technique, for stimuli-responsive release of the drug miltefosine in the lysosome of macrophage RAW 264.7 cell line. A benign polymeric backbone, with a disulfide bonding susceptible to an oxidative cleavage, is utilized for the organelle-specific release of miltefosine. Oxidative rupture of the disulfide bond is induced by intracellular glutathione (GSH) as an endogenous stimulus. Such a stimuli-responsive release of the drug miltefosine in the lysosome of macrophage RAW 264.7 cell line over a few hours helped in achieving an improved drug efficacy by 200 times as compared to pure miltefosine. Such a drug formulation could contribute to a new line of treatment for leishmaniasis.A. Das acknowledges SERB (India) Grants (CRG/2020/000492 and JCB/2017/000004) and DBT Grant (BT/PR22251/NNT/28/1274/2017) for supporting this research. N. Mukherjee acknowledges SERB (India) Grant PDF/2016/001437 and K. Das acknowledges the grant EMR/2015/001674 for supporting this research. Financial support from DST (DST/INSPIRE/03/2017/002477) is acknowledged by R.T. This manuscript bears CSMCRI registration no 7/2021.Pramanik, SK (corresponding author), CSIR Cent Salt & Marine Chem Res Inst, Bhavnagar 364002, Gujarat, India.
Mukherjee, N (corresponding author), CSIR Indian Inst Chem Biol, Canc Biol & Inflammatory Disorder Div, Kolkata 700032, India.
Chattopadhy, S (corresponding author), BITS Pilani, Pilani 403726, Goa, India.
Das, A (corresponding author), Indian Inst Sci Educ & Res Kolkata, Mohanpur 741246, W Bengal, India.
[email protected]; [email protected]; [email protected]
Interview with Indra Das
Get PDFIndra Das is most well-recognized as the author of The Devourers (2015), a novel that won the Lambda Literary Award for straddling the genres of sci-fi, speculative, and fantasy fiction alongside LGBT themes. Das’s short fiction is widely published is horror and sci-fi anthologies, as well as magazines like Tor.com, Strange Horizons, and Asimov’s Science Fiction. He spoke candidly with Alok Amatya over email about the current literary landscape, the work of writing transgressive genre fiction, and his own experiences as an upcoming global author
"PULS." - Ein Blog als Online-Magazin für Medizinstudierende der Goethe-Universität Frankfurt
No full textIm Herbst 2009 forderten Studierende im Rahmen landesweiter Proteste auch am Fachbereich Medizin/Zahnmedizin der Goethe-Universität Frankfurt mehr Transparenz und Kommunikation zu Angelegenheiten ihres Studiums. Einen innovativen Lösungsansatz, um diesen Forderungen nachzukommen, bietet eines der Web 2.0 Werkzeuge: ein auf einer Blog-Software basierendes Online-Magazin für Studierende und andere Mitglieder des Fachbereichs.
Das öffentlich zugängliche Online-Magazin "PULS." (https://newsmagazin.puls.med.uni-frankfurt.de/wp/) wird mit einer freien Blog-Software (wordpress Version 3.1.3.) realisiert und von einer Online-Redakteurin konzipiert und geschrieben. Die Beiträge entstehen nach eigenen Recherchen sowie aus Anregungen und Gesprächen mit verschiedenen Personengruppen des Fachbereichs. Die datenschutzkonforme Auswertung der Zugriffe erfolgt über eine open-source Webanalyse-Software (Piwik). Zusätzlich werden jährlich mit dem Online-Umfrage-Tool Survey Monkey die Nutzer anonym befragt.
"PULS." ist seit dem 14.02.2010 ununterbrochen online und hat seitdem 806 Beiträge (Stand: 27.11.2012) publiziert und wird von ca. 2400 Besuchern monatlich gelesen. Das Themenspektrum ist zentriert auf die Anliegen der Frankfurter Medizin- und Zahnmedizinstudierenden. Die enge Zusammenarbeit mit verschiedenen Gruppierungen des Fachbereichs – Dekanat, Studierende und Lehrende – garantiert darüber hinaus ein fachbereichs-relevantes Themenspektrum. Das Online-Magazin begleitet komplexe Projekte und Entscheidungen mit Hintergrundinformationen und kommuniziert sie verständlich. Eine jährliche Nutzer-Evaluierung zeigt eine wachsende Leserzahl und eine sehr hohe Zustimmung für das Online-Magazin, seine Inhalte und seinen Stil. Das Web 2.0-Medium "Blog" und seine web-typische Sprache entsprechen dem Medienverhalten der Zielgruppe, d.h. den Studierenden des Fachbereichs Medizin.
"PULS." hat sich als ein geeignetes und strategisches Instrument erwiesen, um größere Transparenz, mehr Kommunikation und letztendlich eine stärkere Identifikation der Studierenden mit ihrem Fachbereich voranzutreiben
Die Türkei und das andere Europa : Phantasmen der Identität im Beitrittsdiskurs /
No full textDiese Studie analysiert das dialogische Zusammenspiel zwischen den europäischen und türkischen Diskursen um den möglichen EU-Beitritt der Türkei. Die Differenzen stellen in der Perspektive postkolonialer Theorien ein ambivalentes und formatives Moment für die Bildung einer europäischen Identität dar: Die Europäer nehmen die Beitrittsverhandlungen zum Anlass, über ihr Selbstverständnis zu reflektieren, wobei diverse Ost-West-Repräsentationen kommuniziert und strukturiert werden. Die muslimischen Migranten in Europa und die Minderheiten in der Türkei fungieren dabei als interne Symptome, die die Unvollständigkeit der europäischen bzw. türkischen Identitäten sichtbar machen.Diese Studie analysiert das dialogische Zusammenspiel zwischen den europäischen und türkischen Diskursen um den möglichen EU-Beitritt der Türkei. Die Differenzen stellen in der Perspektive postkolonialer Theorien ein ambivalentes und formatives Moment für die Bildung einer europäischen Identität dar: Die Europäer nehmen die Beitrittsverhandlungen zum Anlass, über ihr Selbstverständnis zu reflektieren, wobei diverse Ost-West-Repräsentationen kommuniziert und strukturiert werden. Die muslimischen Migranten in Europa und die Minderheiten in der Türkei fungieren dabei als interne Symptome, die die Unvollständigkeit der europäischen bzw. türkischen Identitäten sichtbar machen.Bülent Küçük (Dr. phil.) ist Soziologe und arbeitet im Forschungsprojekt "Eurosphere" an der Sabancà Universität in Istanbul. Seine Forschungsschwerpunkte sind Öffentlichkeits-, Diskurs- und Postkoloniale Theorien.Online resource; title from PDF title page (publisher's Web site, viewed October 7 2015).Includes bibliographical references.JSTO
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