324 research outputs found
Gas Chromatographic Enantiomer Separation of Atropisomeric PCBs Using Modified Cyclodextrins as Chiral Phases
Naphthalenones and isocoumarins of the fungus Ceratocystis fimbriata f. sp. platani
The chemical composition of the culture filtrates of Ceratocystis fimbriata f. sp. platani was investigated.
Ten compounds potentially toxic to Platanus acerifolia were isolated and identified. These metabolites were mainly
isocoumarins and naphthalenones. Three of these induced extensive necrosis on plane tree tissues
Chromatographic Properties of Different Methyl—Phenyl (1:1) Substituted Silicone Stationary Phases for Open-Tubular Gas Chromatography
The influence of different configurations of silicones having 50% methyl and 50% phenyl substitution on chromatographic properties, such as polarity and thermal stability, has been systematically investigated. Polysiloxanes composed of dimethyl and diphenyl units show very low levels of column bleed at temperatures up to 370°C, while polymers having methyl—phenyl substitution show severe bleeding at this temperature. The polarity of the latter polymers, as reflected by Kováts indices, is higher than for the polymers composed by dimethyl—diphenyl unit
Synthesis and Activity of Grape Wood Phytotoxins and Related Compounds
The synthesis of analogues and derivatives of two o-hydroxyphenylacetylenes, eutypine and sterehirsutinal,
the main phytotoxins isolated from the culture medium of Eutypa lata and Stereum hirsutum, is reported. Two
means of synthesis are described, based on cyclisation, oxidation, oxidative decarboxylation or reduction reactions,
and producing o-hydroxyphenylacetylene or benzofuran derivatives. Some of these synthetic compounds were tested
on grapevine callus in order to compare their toxicity with the natural analogues
Toward molecular wires confined in zeolite channels for an effective transport of electronic excitation energy.
Sunlight is the fundamental energy source sustaining life on Earth. Green plants are provided of very sophisticated and highly efficient tools to exploit light, they are able to harvest sunlight and to transport electronic excitation energy by means of a particular “antenna system” to reaction centres (natural photosynthesis). The antenna consists of regular arrangements of chlorophyll molecules held at fixed positions by means of proteins. Light absorbed by any of these molecules is transported - by radiationless energy transfer (FRET) - to reaction centres, providing the energy necessary for the chemical processes to be initiated. A green leaf consists of millions of such well-organized antenna devices. A long-standing challenge has been the development of an artificial system able to mimic the photosynthetic system. Artificial antenna systems can be realized once several organized chromophores are able to absorb the incident light and to channel the excitation energy to a common acceptor component1-3. Artificial antenna can be built by incorporating dyes into the one-dimensional channels of zeolite L (ZL). ZL crystals feature strictly parallel nano sized channels arranged in hexagonal symmetry. These channels can be filled with high concentration of suitable guests. The geometric constraints imposed by the host structure allow achieving supramolecular organization of photoactive guests1. It has been shown2,that the properties of the dye-ZL systems depend on the molecular packing inside the channels, controlling the intermolecular and the dyes/framework interactions
In this work we presents a study on the optical properties of a two –dyes antenna system in which fluorenone molecules (donor molecule) and thionine(acceptor molecule) are organized in Zeolite L porosities.
To interpret the optical properties of the hybrids a detailed structural study at atomistic level was mandatory. Due to the impossibility of studying from the structural point of view a two –dyes systems, two “one-dye” hybrids (ZL/fluorenone and ZL/thionine) were firstly synthesized and characterized to investigate the intermolecular and the dyes/framework interactions4.
The results of thermogravimetric, IR, and X-ray structural refinements carried out for the one-dye system ZL/FL established that 1.5 molecules per unit cell is the maximum FL loading , in contrast with the data reported previously in literature5 and that the FL carbonyl group strong interact with a K+ of the ZL. The FL distribution at maximum loading can be consider as a self-assembly of planar dye molecules into a noncovalent nanoladder.
FL molecules organized in such a single, continuous nanostructure of dye molecules did not exhibit significant electronic interactions. Indeed, both absorption (recorded in the diffuse reflectance mode) and photoemission electronic spectra of ZL/FL systems with different FL loading scaled almost linearly in intensity with the amount dye hosted in the unit cell (ranging from 0.5 to 1.5), without significant changes of the spectral profiles. Noticeably, the combination and steady state and time resolved photoluminescence data indicated that even at the maximum loading ca. 90% of FL molecules are photoluminescent, with significant increase in the average quantum yield with respect to FL molecules in solution. Such a finding clearly indicates that excited states coupling (Davydov splitting) is not contributing to the optical properties of the material.
The structural study of the ZL/TH system revealed that the maximum possible loading of TH is equal to 0.3 molecules per unit cell in agreement with the TGA and literature data6. Short distances between the carbon, sulfur and nitrogen atoms and two water molecule sites , in turn at bond distance from the oxygen atoms of the main channel, suggested a water-mediated Th-ZL interactions7. Moreover, IR spectroscopy provided evidence of the interaction of the aromatic rings with the environment. This likely resulted in an increase of the rate of non-radiative decay of Th molecules in the electronic excited state, because only ca. 5% of Th molecules hosted in the ZL channel appeared photoluminescent.
The occurrence of energy transfer from excited FL molecules forming the noncovalent nanoladder in the ZL channels and Th, in the ground state, deposited on the external surface of ZL particles are currently under investigation.
In conclusion, we have here presented a study on the physico-chemical properties of dense molecular wires encapsulated in the one-dimensional pores arrays of Zeolite L. Concerning the optical properties of our composites, no evidence of Davydov splitting emerged from our study, indicating that one of the main competitors of the FRET mechanism is not operative notwithstanding the close packed arrangement of FL. We believe that this feature is of overwhelming relevance in view of application of such a system in artificial antenna systems
Skin cancer precursor immunotherapy for squamous cell carcinoma prevention
BACKGROUND: Topical calcipotriol plus 5-fluorouracil (5-FU) combination is an effective immunotherapy against actinic keratosis (AK), which is a precursor to squamous cell carcinoma (SCC). However, the long-term effectiveness of calcipotriol plus 5-FU treatment for SCC prevention is unknown.
METHODS: We performed a blinded prospective cohort study on participants of a randomized double-blind clinical trial in which a 4-day course of topical calcipotriol plus 5-FU combination was compared to Vaseline plus 5-FU (control) for AK treatment. SCC and basal cell carcinoma (BCC) incidences were assessed at 1, 2, and 3 years after trial. Tissues were analyzed for calcipotriol plus 5-FU-induced T cell immunity in the skin.
RESULTS: Calcipotriol plus 5-FU-induced tissue-resident memory T (Trm) cell formation in face and scalp skin associated with significantly higher erythema scores compared with control (P \u3c 0.01). Importantly, more participants in the test cohort remained SCC-free over the more than 1,500-day follow-up period (P = 0.0765), and significantly fewer developed SCC on the treated face and scalp within 3 years (2 of 30 [7%] versus 11 of 40 [28%] in control group, hazard ratio 0.215 [95% CI: 0.048-0.972], P = 0.032). Accordingly, significantly more epidermal Trm cells persisted in the calcipotriol plus 5-FU-treated face and scalp skin compared with control (P = 0.0028). There was no significant difference in BCC incidence between the treatment groups.
CONCLUSION: A short course of calcipotriol plus 5-FU treatment on the face and scalp is associated with induction of robust T cell immunity and Trm formation against AKs and significantly lowers the risk of SCC development within 3 years of treatment.
FUNDING: This research was supported by internal academic funds and by grants from the Burroughs Wellcome Fund, Sidney Kimmel Foundation, Cancer Research Institute, and NIH
Molecular wires confined in zeolite L channels for an effective transport of electronic excitation energy: a synchrotron structural study.
Sunlight is the fundamental energy source sustaining life on Earth. Green plants are provided of very sophisticated and highly efficient tools to exploit light, they are able to harvest sunlight and to transport electronic excitation energy by means of a particular \u201cantenna system\u201d to reaction centers (natural photosynthesis).The development of an artificial system able to mimic the natural phenomenon has been a long-standing challenge. Artificial antenna systems can be realized once several organized chromophores are able to absorb the incident light and to channel the excitation energy to a common acceptor component [1-3]. The optical properties of the systems depend on the molecular packing inside the channels. Artificial antenna can be built by incorporating suitable guests into the one-dimensional channels of zeolite L (ZL). In this work we present a detailed structural study of two hybrid systems in which dyes (fluorenone and thionine) are encapsulated in zeolite L channels. These two molecules were chosen since it has been demonstrated that a \u201ctwo \u2013dyes antenna system\u201d - in which fluorenone (FL) (donor molecule) and thionine (Th) (acceptor molecule) are organized in Zeolite L porosities - shows remarkable optical properties. Due to the impossibility of studying, from the structural point of view a \u201ctwo \u2013dyes systems\u201d, two \u201cone-dye\u201d hybrids (ZL/fluorenone and ZL/thionine) were firstly synthesized and characterized [4].
The results of thermogravimetric, IR, and X-ray structural refinements carried out for the one-dye ZL/FL and ZL/Th systems established that 1.5 molecules of FL and 0.3 molecules of Th per unit cell is the maximum loading, respectively. The FL carbonyl group strong interacts with a K+ of the ZL. On the other hand, short distances between the carbon, sulfur and nitrogen atoms of Th and two water molecule sites, in turn at bond distance from the oxygen atoms of the main channel, suggested a water-mediated Th-ZL interactions. The energy transfer from excited FL molecules, forming the non-covalent nano-ladder in the ZL channel, and Th, deposited on the external surface of ZL particles, is currently under investigation.
In conclusion concerning the optical properties of our composites, no evidence of Davydov splitting emerged from our study, indicating that one of the main competitors of the FRET mechanism is not operative notwithstanding the close packed arrangement of FL. We believe that this feature is of overwhelming relevance in view of application of such a system in artificial antenna devices.
The authors acknowledge the Italian Ministry of Education, MIUR-Project: \u201cFuturo in Ricerca 2012 - ImPACT- RBFR12CLQD\u201d
Field-based tests for the assessment of physical fitness in children and adolescents practicing sport: A systematic review within the ESA program
High levels of physical fitness (PF) can positively affect both health and cognitive function, thus monitoring its levels in youth can help increase health and quality of life in adult populations later on. This systematic review aims to identify PF field-based tests used in young European populations practicing sport to find tools that are adequate for the considered target involving a new battery within the Enriched Sport Activities (ESA) project. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed. In the 83 identified articles, the main tests used were: vertical/horizontal jumps (for muscular strength/power); push-ups, running at maximum effort, sit-ups (for muscular strength/endurance); multistage non-intermittent and intermittent tests (for aerobic endurance); sit and reach (for flexibility); sprinting and agility T-tests (for speed and agility, respectively); 10 x 5 m shuttle run (SR) (for both speed and agility). Few studies assessed coordination, reaction time, power, and balance. Although the selected tests are widely used and validated, they do not determine all PF aspects and do not reflect sport-specific features. A final decision was made for the inclusion of the following tests: standing broad jump, seated medicine ball throw, 20 m SR test, 30 m sprint, Illinois test, and a new test, i.e., the crunning test, to assess different skill-related components at once. The use of this combination of tests allows for the assessment of all PF components and can help planning eective training programs and cultivate sporting talent
Dye Loading influence on performances of Fluorenone/zeoliteL Light Harvester
Zeolite L (LTL), is an appealing and excellent host for the supramolecular organization of different kinds of molecules and complexes. However, relatively few experimental structural information is available about the orientation and alignment of the dye molecules in the zeolite pores. Hence, a detailed structural characterization is of great importance for understanding the functionality of these host-guest systems. Between all the possible guests, neutral dye fluorenone (C13H8O) (FL) has received a considerable attention [1,2] because of its ability to form a host-guest complex with LTL, stable if exposed at the atmosphere. Moreover, the fluorescent nature of fluorenone makes this complex interesting as a component of the energy relay system in artificial antennas. Although a detailed structural characterization is still lacking, theoretical studies have shown as the orientation of fluorenone is especially interesting as it is directly related to the light harvesting properties of fluorenone [3]. Moreover, it has shown as the presence of water can influence on the electronic spectra of this host-guest complex and then affect its performances as light harvester [3].
In this study, three different FL/K-LTL materials characterized by an increasing loading of FL have been synthesized by mixing in inert atmosphere the dehydrated K-LTL and FL powder in ratio of 0.5, 1.0, 1.5 and 2.0 molecules/unit cell, and then heating the samples at 120°C in air for 24 h. The vials were maintained under continuous rotation during the heating in order to optimize the contact between the zeolite and the dye. The samples so obtained were characterized by means of X-ray powder diffraction, thermo-gravimetric analysis, IR and UV-vis spectroscopies, fluorescence and nitrogen adsorption.
The incorporation of FL into the K-LTL channels was confirmed by a significant change of the unit cell parameters and by drastic decrease in the K-LTL surface area also at low FL loading. The strong interaction between FL carbonyl group and the extraframework potassium cation predicted by theoretical modelling [1] was confirmed by the short bond distances (2.77 Ă…), evidenced in the Rietveld refined structure, and by the shift of the C=O stretching frequency evidenced in the IR spectra. Such an interaction explains why FL is not displaced by water molecules when FL/K-LTL hybrid is re-exposed to the air [1].
Interestingly, although the UV-vis absorption spectrum was almost unaffected by the FL loading, the corresponding emission spectrum evidenced a strong influence: the optimum FL/K-LTL ratio was then determined in order to optimize the performances of the device as light harvester. The structural information obtained theoretically and from XRD allowed also to explain the loading dependence of the optical properties of the material and to correlate it with the relative orientation of the fluorenone molecules in the zeolite channels
[68Ga]Ga-DOTANOC Uptake at Pancreatic Head/Uncinate Process: Is It a Persistent Diagnostic Pitfall Over Time?
Simple Summary The purpose of the present study is to describe the frequency of non-malignant [68Ga]Ga-DOTANOC uncinate process (UP) uptake and to evaluate its variations over time. Among the first 6 months of enrolment of a monocentric prospective observational electronic archive, analyses of a large number of PET/CT scans (n = 268) of NEN pts (n = 172) demonstrated that: UP uptake is a frequent finding (observed in almost half of the cases, slightly higher than previously reported), mostly presenting with a diffuse pattern and, interestingly, characterized by variations over time in almost one third of the cases. The consciousness of this diagnostic pitfall is of utmost importance for accurate [68Ga]Ga-DOTANOC PET/CT reporting, since the pancreas represents one of the most frequent sites of NEN. Purpose: [68Ga]Ga-DOTA-peptide uptake in the pancreatic head/uncinate process (UP) is a frequent PET/CT finding. Although mostly physiologic, it can represent a pitfall in PET/CT reading, especially when focal. An increased frequency of UP uptake has been reported in patients (pts) affected by diabetes mellitus (DM). The aim of the study is to describe the frequency of [68Ga]Ga-DOTANOC UP uptake to evaluate its variations over time and its possible correlation with DM. Methods: In September 2017, a monocentric prospective observational electronic archive was initiated at our center to collect clinical and imaging data of pts undergoing [68Ga]Ga-DOTANOC PET/CT. Among the pts enrolled in the first 6 months (Sept 2017 to Feb 2018), those presenting [68Ga]Ga-DOTANOC PET/CT uptake at UP level were included. Pts with UP lesions already documented on CT/MRI or those that underwent surgical excision of UP before PET/CT were excluded from the analysis. [68Ga]Ga-DOTANOC UP uptake was classified as diffuse or focal and compared with the pattern observed in previous PET/CT scans performed at our center. An increased frequency of UP uptake was also correlated with the presence of DM. Results: In the first 6 months, 253 pts were enrolled in the archive and 172 out of them were included in the analysis. UP increased uptake was frequently observed (77/172, 44.8%) and was mostly diffuse (62/77). In 75/172 pts (43.6%), previous [68Ga]Ga-DOTANOC PET/CT scans were available (overall 268 scans; number of previous PET per pt range: 1-20) and were retrospectively reviewed. Despite the fact that, in most pts, the uptake pattern was stable over time (54/75 pts, 72%), it changed in approximately one third of cases (21/75, 28%). Among DM pts (29/172), only 10/29 (34.4%) presented increased UP uptake. Conclusions: UP [68Ga]Ga-DOTANOC uptake is a frequent non-malignant finding (slightly higher than previously reported), mostly presenting with a diffuse pattern. However, contrary to previous reports, our data show that the pattern of uptake may vary over time in approximately one third of the cases and it is not more frequently observed in pts with DM
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