4,493 research outputs found
A novel DR/NIR T-shaped aiegen: Synthesis and x-ray crystal structure study
We developed a new benzodifuran derivative as the condensation product between 2,6-diamino-4-(4-nitrophenyl)benzo[1,2-b:4,5-bâ]difuran-3,7-dicarboxylate and 3-hydroxy-2-naphthaldehyde. The intramolecular hydrogen-bond interactions in the terminal half-salen moieties produce a sterically encumbered highly conjugated main plane and a D-A-D (donor-acceptor-donor) T-shaped structure. The novel AIEgen (aggregation-induced enhanced emission generator) fulfils the requirement of RIR (restriction of intramolecular rotation) molecules. DR/NIR (deep red/near infrared) emission was recorded in solution and in the solid state, with a noteworthy photoluminescence quantum yield recorded on the neat crystals which undergo some mechanochromism. The crystal structure study of the probe from data collected at a synchrotron X-ray source shows a main aromatic plane Ï-stacked in a columnar arrangement
Millimeter-Waves Structures on Benzocyclobutene Dielectric Substrate
The need of low-loss substrate materials with stable dielectric performances is a strong requirement when working at millimeter frequencies, where standard dielectrics exhibit prohibitive losses. In this paper, the authors focus their attention on a polymer material, the benzocyclobutene (BCB), having a low dielectric constant and a low loss tangent, with a stable behavior up to THz frequencies. A specific in-house manufacture technology is described to realize millimeter-wave structures on a BCB dielectric substrate. Experimental validations on BCB-based circuits and antennas prototypes are discussed
Formamide as the main building block in the origin of nucleic acids
The simplest molecules grouping the four most common elements of the universe H,C,O and N (with the exception of the biologically inert He) are isocyanate HNCO and formamide H2NCOH. Reasons for the availability of formamide on prebiotic Earth are presented. We review evidence showing that formamide in the presence of largely available catalysts and by moderate heating yields the complete set of nucleic bases necessary for the formation of nucleic acids. Formamide also favours the formation of acyclonucleosides and the phosphorylation and trans-phosphorylation of nucleosides, thus providing a plausible chemical frame for the passage from a simple one-carbon compound to nucleic polymers. Physico-chemical conditions exist in which formamide favours the stability of the phosphoester bonds in nucleic polymers relative to that of the same bonds in monomers. Starting from a formamide-laden environment subject only to the laws of chemistry, a hypothesis is outlined sketching the passage towards an aqueous world in which Darwinian rules apply
Radar array diagnosis from undersampled data using a compressed sensing/sparse recovery technique
A Compressed Sensing/Sparse Recovery approach is adopted in this paper for the accurate diagnosis of fault array elements from undersampled data. Experimental validations on a slotted waveguide test array are discussed to demonstrate the effectiveness of the proposed procedure in the failures retrieval from a small set of measurements with respect to the number of radiating elements. Due to the sparsity feature of the proposed formulation, the method is particularly appealing for the diagnostics of large arrays, typically adopted for radar applications
Efalizumab
Introduction: Conventional systemic therapies for psoriasis are associated with serious toxicities that can limit long-term use. In recent years, biological therapies have offered the possibility of long-term therapy with improved safety and efficacy for the treatment of psoriasis. Biological therapies can be classified into three categories: the T-cell modulating agents (alefacept and efalizumab), the inhibitors of TNF-alpha (adalimumab, etanercept, infliximab) and the inhibitors of IL-12 and -23 (ustekinumab). Efalizumab is a humanized recombinant monoclonal IgG1 antibody. It targets multiple stages in the immunopathogenesis of psoriasis: initial T-cell activation, migration of T-cells into dermal and epidermal tissues, and T-cell reactivation. On 19 February 2009, the Committee for Medicinal Products for Human Use (CHMP) recommended the suspension of the marketing authorisation for efalizumab.Areas covered: Numerous clinical trials have demonstrated the efficacy, safety and health-related quality of life benefits of efalizumab in patients with moderate-to-severe chronic plaque psoriasis. Efalizumab was approved by the FDA in November 2003 and by the European Medicines Evaluation Agency in September 2004 for the treatment of adult patients with moderate-to-severe chronic plaque psoriasis. Recently, three cases of progressive multifocal leukoencephalopathy were described in patients on long-term (> 3 years) efalizumab therapy, leading to its withdrawal from the market.Expert opinion: Although initially favorable, the safety profile of efalizumab revealed the appearance of severe adverse events in long-term treated patients. Therefore, post-marketing surveillance is essential for correct evaluation of drug potential
Tunable Reflectarray Cell for Wide Angle Beam-Steering Radar Applications
An electronically tunable reflectarray element is proposed in this work to design beam-steering antennas useful for radar applications. A reduced size reflectarray unit cell is properly synthesized in order to extend the antenna beam scanning capabilities within a wider angular region. The radiating structure is accurately optimized to provide a full phase tuning range by adopting a single varactor load as phase shifter element. A 0.46 -reflectarray cell is designed at the frequency of 11.5 GHz, obtaining a phase agility of about 330 â . The cell is successfully adopted for the design of a 21 Ă 21 reconfigurable reflectarray. The antenna is numerically tested for different configurations of the varactors capacitance values, and good beam-steering performances are demonstrated within a wide angular range
p53-Mediated downregulation of H ferritin promoter transcriptional efficiency via NF-Y
The tumor suppressor protein p53 triggers many of the cellular responses to DNA damage by regulating the transcription of a
series of downstream target genes. p53 acts on the promoter of the target genes by interacting with the trimeric transcription factor
NF-Y. H ferritin promoter activity is tightly dependent on a multiprotein complex called Bbf; on this complex NF-Y plays a major
role.
The aim of this work was to study the modulation of H ferritin expression levels by p53. CAT reporter assays indicate that: (i)
p53 overexpression strongly downregulates the transcriptional efficiency driven by an H ferritin promoter construct containing only
the NF-Y recognition sequence and that the phenomenon is reverted by p53 siRNA; (ii) the p53 C-terminal region is sufficient to
elicitate this regulation and that a correct C-terminal acetylation is also required. The H ferritin promoter displays no p53-binding
sites; chromatin immunoprecipitation assays indicate that p53 is recruited on this promoter by NF-Y. The p53âNF-Y interaction
does not alter the NF-Y DNA-binding ability as indicated by electrophoretic mobility shift assay (EMSA) analysis.
These results demonstrate that the gene coding for the H ferritin protein belongs to the family of p53-regulated genes, therefore
adding a new level of complexity to the regulation of the H ferritin transcription and delineate a role for this protein in a series of
cellular events triggered by p53 activation
Multiparameter characterisation of vertebral osteoporosis with 3-T MR = Valutazione multiparametrica dellâosteoporosi vertebrale con RM a 3 Tesla
Purpose. This study was undertaken to evaluate the diagnostic capabilities of 3-Tesla (T) magnetic resonance (MR) in vertebral osteoporosis. Materials and methods. Thirty subjects (ten healthy controls, ten with osteoporosis but no fracture, ten with osteoporotic vertebral fractures) underwent MR of the lumbar spine. Turbo spin echo (TSE) T1-, T2- and T2- spectral selection attenuated inversion recovery (SPAIR) weighted imaging and spectroscopy for the selective evaluation of water and fat content were performed. The apparent diffusion coefficient (ADC) was calculated, and diffusion tensor imaging (DTI) was performed to create a map of the spatial arrangement of the tissue structures. Results. Morphological imaging detected recent vertebral fractures. In osteoporotic patients, spectroscopic imaging demonstrated an increase in the saturated fats and a decrease in the ADC, whereas the data provided by DTI demonstrated a bone structure with medium-degree anisotropy. Discussion. Osteoporosis is characterised by trabecular thinning, with an increase in the intertrabecular spaces, which are filled with fats. The anisotropic study and the subsequent assessment of colour and vector maps can provide a noninvasive tool for assessing the risk of fracture due to osteoporosis
Targeting Food Allergy with Probiotics.
The dramatic increase in food allergy prevalence
and severity globally is demanding
effective strategies. Food allergy derives from
a defect in immune tolerance mechanisms.
Immune tolerance is modulated by gut
microbiota composition and function, and gut
microbiota dysbiosis has been associated with
the development of food allergy. Selected probiotic
strains could act on immune tolerance
mechanisms. The mechanisms are multiple
and still not completely defined. Increasing
evidence is providing useful information on
the choice of optimal bacterial species/strains,
dosage, and timing for intervention. The
increased knowledge on the crucial role played
by gut microbiota-derived metabolites, such as
butyrate, is also opening the way to a postbiotic
approach in the stimulation of immune
tolerance
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