Science and technology of BOREXINO: A Real time detector for low-energy solar neutrinos: A Real Time Detector for Low Energy Solar Neutrinos

BOREXINO, a real-time device for low energy neutrino spectroscopy is nearing completion of construction in the underground laboratories at Gran Sasso, Italy (LNGS). The experiment's goal is the direct measurement of the flux of 7Be solar neutrinos of all flavors via neutrino-electron scattering in an ultra-pure scintillation liquid. Seeded by a series of innovations which were brought to fruition by large scale operation of a 4-ton test detector at LNGS, a new technology has been developed for BOREXINO. It enables sub-MeV solar neutrino spectroscopy for the first time. This paper describes the design of BOREXINO, the various facilities essential to its operation, its spectroscopic and background suppression capabilities and a prognosis of the impact of its results towards resolving the solar neutrino problem. BOREXINO will also address several other frontier questions in particle physics, astrophysics and geophysics

The Loss of the p53 Activator HIPK2 Is Responsible for Galectin-3 Overexpression in Well Differentiated Thyroid Carcinomas

Background: Galectin-3 (Gal-3) is an anti-apoptotic molecule involved in thyroid cells transformation. It is specifically overexpressed in thyroid tumour cells and is currently used as a preoperative diagnostic marker of thyroid malignancy. Gal-3 expression is downregulated by wt-p53 at the transcriptional level. In well-differentiated thyroid carcinomas (WDTCs) there is an unexplained paradoxical concomitant expression of Gal-3 and wt-p53. HIPK2 is a co-regulator of different transcription factors, and modulates basic cellular processes mainly through the activation of wt-p53. Since we demonstrated that HIPK2 is involved in p53-mediated Gal-3 downregulation, we asked whether HIPK2 deficiency might be responsible for such paradoxical Gal-3 overexpression in WDTC. Methodology/Principal Findings: We analyzed HIPK2 protein and mRNA levels, as well as loss of heterozygosity (LOH) at the HIPK2 locus (7q32-34), in thyroid tissue samples. HIPK2 protein levels were high in all follicular hyperplasias (FHs) analyzed. Conversely, HIPK2 was undetectable in 91.7% of papillary thyroid carcinomas (PTCs) and in 60.0% of follicular thyroid carcinomas (FTCs). HIPK2 mRNA levels were upregulated in FH compared to normal thyroid tissue (NTT), while PTC showed mean HIPK2 mRNA levels lower than FH and, in 61.5% of cases, also lower than NTT. We found LOH at HIPK-2 gene locus in 37.5% of PTCs, 14.3% of FTCs and 18.2% of follicular adenomas. To causally link these data with Gal-3 upregulation, we performed in vitro experiments, using the PTC-derived K1 cells, in which HIPK2 expression was manipulated by RNA interference (RNAi) or plasmid-mediated overexpression. HIPK2 RNAi was associated with Gal-3 upregulation, while HIPK2 overexpression with Gal-3 downregulation. Conclusions/Significance: Our results indicate that HIPK2 expression and function are impaired in WDTCs, in particular in PTCs, and that this event explains Gal-3 overexpression typically observed in these types of tumours. Therefore, HIPK2 can be considered as a new tumour suppressor gene for thyroid cancers

Dinuclear rhenium complexes highly luminescent in solid state

The interest for luminescent materials able to efficiently emit in solid state is continuously growing, because in most applications the dyes are used as solid film. Concentration-quenching effects, affecting both organic and organometallic emitters [1-2] usually decrease PLQY in solid state. We present here a series of dinuclear Re(I) complexes whose emission is higher in solid state than in solution, and strongly depends on the nature of the halide ancillary ligand. These complexes belong to the family of neutral tricarbonyl Re(I) complexes with general formula [Re2(CO)6(\uf06d-1,2-diazine)(\uf06d-X)2], where X could be halogen or hydride [3]. Some of them have recently gained interest for their intense yellow/green emission, occurring from triplet metal-to-ligand charge transfer (3MLCT) states [4], showing a modulation effect of the diazine substituents on wavelengths, lifetimes and quantum yields of the emission. Photoluminescent quantum yield (PLQY) up to 0.53 have been measured for the di-chloro complexes containing diazines bearing alkyl groups in both the \uf062 positions [5]. These properties allowed their successful use as phosphorescent dopants in organic light emitting devices (OLEDs) [5]. The influence of the halide ancillary ligand on the photophysical properties has been previously discussed in solution [2, 4]. Differently from the di-chloro derivative 1, the analogous di-bromo and di-iodo derivatives 2 and 3 are almost no emissive. We have now found an opposite behaviour in solid state. In fact all the complexes are very brilliant, showing intense yellow-orange emission whose maximum shifts to higher energy on going from 1 to 3 (from 560 nm for 1 and 2 to 548 nm for 3) with PLQY relatively low for 1 and higher for 2 and 3 (up to 0.50 for complex 2). This very high Aggregation Induced Emission (AIE) [6] will be discussed in terms of the restriction of the intramolecular roto-vibrational motions of the \u201cRe2(CO)6(\uf06d-X)2\u201d scaffold imposed by the rigid environment, as evidenced by the strong decrease of the knr. Moreover a parallel increase of kr is noticed, which clearly shows the influence of the halides on determining not only the energy of the excited state, but also the nature of the lowest (emitting) state [7]