Attachment--and loss.

Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

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Climate Change 2007: The Physical Science Basis.

The detection of psychiatric illness by questionnaire

Abstract A two-dimensional version of the Pennsylvania State University mesoscale model has been applied to Winter Monsoon Experiment data in order to simulate the diurnally occurring convection observed over the South China Sea. The domain includes a representation of part of Borneo as well as the sea so that the model can simulate the initiation of convection. Also included in the model are parameterizations of mesoscale ice phase and moisture processes and longwave and shortwave radiation with a diurnal cycle. This allows use of the model to test the relative importance of various heating mechanisms to the stratiform cloud deck, which typically occupies several hundred kilometers of the domain. Frank and Cohen's cumulus parameterization scheme is employed to represent vital unresolved vertical transports in the convective area. The major conclusions are: Ice phase processes are important in determining the level of maximum large-scale heating and vertical motion because there is a strong anvil componen...

Numerical study of convection observed during the Winter Monsoon Experiment using a mesoscale two-dimensional model [presentation]

Fluorescent carbon nanoparticles or carbon quantum dots (CQDs) are a new class of carbon nanomaterials that have emerged recently and have garnered much interest as potential competitors to conventional semiconductor quantum dots. In addition to their comparable optical properties, CQDs have the desired advantages of low toxicity, environmental friendliness low cost and simple synthetic routes. Moreover, surface passivation and functionalization of CQDs allow for the control of their physicochemical properties. Since their discovery, CQDs have found many applications in the fields of chemical sensing, biosensing, bioimaging, nanomedicine, photocatalysis and electrocatalysis. This article reviews the progress in the research and development of CQDs with an emphasis on their synthesis, functionalization and technical applications along with some discussion on challenges and perspectives in this exciting and promising field.

Carbon quantum dots and their applications

In this study, the effect of mechanical stresses on the recrystallization behavior of Sn-3.0Ag-0.5Cu Pb-free solder interconnects was studied by four-point cyclic bending, shear tests, and tensile tests. Scanning electronic microscopy with electron backscattered diffraction was used to characterize the microstructure and crystallographic orientation of the solder interconnects. The results show that recrystallization occurs under the different mechanical stresses in these tests at room temperature, and that recrystallized grains evolve from subgrains by rotation. Microhardness measurements after shear tests show that the hardness of the recrystallized microstructure was decreased by 15% and 41%, respectively, compared with that of the nonrecrystallized and as-solidified microstructures. Furthermore, the fine-grained microstructure produced after recrystallization facilitated grain boundary sliding. Therefore, the deformation and cracking behaviors were localized in the degraded recrystallized microstructures once recrystallization occurred, accelerating failure of the solder interconnects.

Grain Orientation Evolution and Deformation Behaviors in Pb-Free Solder Interconnects Under Mechanical Stresses

Sonic hedgehog (Shh) in dental epithelium regulates tooth morphogenesis by epithelial-mesenchymal signaling transduction. However, the action of Shh signaling regulation in this process is not well understood. Here we find that mesenchymal Suppressor of Fused (Sufu), a major negative regulator of Shh signaling, plays an important role in modulating the tooth germ morphogenesis during the bud-to-cap stage transition. Deletion of Sufu in dental mesenchyme by Dermo1-Cre mice leads to delayed development of mandibular molar into cap stage with defect of primary enamel knot (EK) formation. We show the disruption of cell proliferation and programmed cell death in dental epithelium and mesenchyme in Sufu mutants. Epithelial-specific adhesion molecule E-cadherin is evidently reduced in the bilateral basal cells of tooth germ at E14.5. The cells in the presumptive EK, predominantly expressing P-cadherin, appear stratified but fail to condense. Moreover, the transcripts of primary EK marker genes, including Shh, Fgf4, and p21, are significantly decreased compared to controls. In contrast, we find that deficiency of Sufu results in elevation of Shh signaling in mesenchyme, indicated by the significant upregulation of Gli1 and Ptch1. Meanwhile, the expression of Bmp4 and Fgf3, the critical factors of mesenchymal-epithelial induction, is significantly inhibited in dental mesenchyme. Furthermore, the expression of Runx2 experiences a transient decrease at the bud stage. Taken together, these data suggest that mesenchymal Sufu is necessary for tuning the Shh signaling, which may act as an upstream modulator of Bmp4 and Fgf3 to coordinate the interplay between the dental mesenchyme and epithelium of tooth germ.

Mesenchymal Sufu Regulates Development of Mandibular Molars via Shh Signaling

Magnetic Energy Conversion and Transport in the Terrestrial Magnetotail Due to Dipolarization Fronts

A cavity ring down spectroscopy instrument was introduced and designed for measuring extinction efficiencies of pure and mixing aerosols in this paper. Through averaging 500 individual waveforms, the minimal detectable aerosol extinction coefficient of 8.4 × 10−7 m−1 was achieved. By the test results using the NaCl particles, we concluded that this system could measure the extinction efficiencies of an aerosol with an uncertainty less than 3% under laboratory controlled experimental conditions. The refractive indices of different aerosols were retrieved through comparing the measured extinction efficiencies of each aerosol type with which predicted by Mie theory. Aerosols composed of ammonium sulphate and succinic acid with different weight ratios were used to create a model of mixed aerosols using these two materials, whose extinction efficiencies and complex refractive indices were derived. The refractive indices of the mixed aerosols were also calculated by various optical mixing rules. We found that all the molar refraction/absorption mixing rule, the volume ratio linear rule, and Maxwell-Garnett rule did provide comparable results, of which the volume ratio linear rule gave a slightly worse fit than the others.

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Extinction efficiencies of mixed aerosols measured by aerosol cavity ring down spectrometry

SrPt${}_{2}$As${}_{2}$ single crystals with CaBe${}_{2}$Ge${}_{2}$-type structure were synthesized by self-melting technique. X-ray diffraction, transmission electron microscopy, electrical resistivity, magnetic susceptibility, specific heat, and optical spectroscopy measurements were conducted to elucidate the properties of SrPt${}_{2}$As${}_{2}$. SrPt${}_{2}$As${}_{2}$ single crystals undergo a structural phase transition well above room temperature (about 450 K) and become superconducting at 5.18 K. The superconducting and structural phase transition temperatures are reduced by 6$%$ iridium doping. Both the pure SrPt${}_{2}$As${}_{2}$ and the Ir-doped single crystals are demonstrated to be highly metallic with rather high plasma frequencies. In particular, the optical spectroscopy measurement revealed two gaplike suppression structures: a stronger one at high energy near 12 000 cm${}^{\ensuremath{-}1}$ ($\ensuremath{\sim}$1.5 eV), and a less prominent one at lower energy near 3200 cm${}^{\ensuremath{-}1}$ ($\ensuremath{\sim}$0.4 eV) for the pure compound. We elaborate that the former is related to the correlation effect, while the latter could be attributed to the partial energy gap formation associated with structural phase transition.

Lei Wang

Papers

Grain Orientation Evolution and Deformation Behaviors in Pb-Free Solder Interconnects Under Mechanical Stresses

Mesenchymal Sufu Regulates Development of Mandibular Molars via Shh Signaling

Magnetic Energy Conversion and Transport in the Terrestrial Magnetotail Due to Dipolarization Fronts

Extinction efficiencies of mixed aerosols measured by aerosol cavity ring down spectrometry

Single-crystal growth and optical conductivity of SrPt 2 As 2 superconductors