Determinazione della massa in astrofisica

Analisi della Massa come grandezza fisica. Accenni ai metodi utilizzati in Astrofisica per la sua misurazione; massa di Jeans; Materia Oscura; limite di Chandrasekhar; diagramma H-R; sistemi doppi; trasferimento di massa e Funzione di massa

Aglomeración y dispersión poblacional en Siria entre el Bronce Tardío y el Hierro II

In many contexts of ancient Syria, recurring processes leading to the concentration of people in urban centers and their dispersal in smaller settlements, or through mobile practices and/or residential flexibility, are attested. Although in the past the successive crises of cities, urbanism and the State have been related to the decrease of agglomeration and to the population dispersal, the issue appears more complex and diversified when focused on specific situations. By following the spatial and socio-political conditions of the Jabbul and Jazr plains, in Inner Syria, from the Late Bronze Age to Iron Age II, it becomes apparent that, although processes of agglomeration and dispersal are visible, they do not match some usual narratives regarding the settlement patterns of these periods. Also, it will be argued that the spatial conditions of the different contexts, including the agglomeration and dispersal of people, impacted on the social and political practices of human groups.En diversos contextos de la Siria antigua se atestiguan procesos recurrentes de concentración de poblaciones en sitios urbanos y de dispersión en asentamientos menores o a través de prácticas móviles o de residencialidad flexible. Si bien se solían relacionar las sucesivas crisis de las ciudades, el urbanismo y el estado con el descenso de la aglomeración y con la dispersión poblacional, el panorama aparece como más complejo y diversificado si se pone el foco en situaciones específicas. A partir de un seguimiento de las condiciones espaciales y sociopolíticas de las llanuras de Jabbul y Jazr, ubicadas en el interior de Siria, desde el Bronce Tardío hasta el Hierro II, se podrá advertir que, si bien se atestiguan procesos de aglomeración y dispersión, estos no coinciden con ciertas esquematizaciones habituales sobre los procesos de asentamiento en dichos períodos. Además, se argumentará que las condiciones espaciales de los diversos contextos, de las cuales forman parte la aglomeración y dispersión, condicionaban las prácticas sociopolíticas de los grupos humanos

NIR-emission from Yb(III)- and Nd(III)-based complexes in the solid state sensitized by a ligand system absorbing in a broad UV and visible spectral window

In this contribution, we present the synthesis, characterization and spectroscopic investigation of the heteroleptic (R,R)-YbL1(tta) and (R,R)-NdL1(tta) complexes (with tta = 2-thenoyltrifluoroacetonate and L1 = N,N'-bis(2-(8-hydroxyquinolinate)methylidene)-1,2-(R,R or S,S)-cyclohexanediamine) in the solid state. The f-f metal-centered NIR luminescence emission of Nd(III) and Yb(III) is efficiently sensitized by both chromophoric ligands in a very broad range of wavelengths [from 250 to 600 nm, in the case of Nd(III) and from 250 to 650 nm, for Yb(III)]. A possible energy transfer mechanism is proposed: for (R,R)-NdL1(tta) complex a classical Ligand-to-Metal Energy Transfer (LMET) mechanism (antenna effect) is suggested, whilst in the case of the (R,R)-YbL1(tta) complex, the presence of a ligand-to-metal charge transfer (LMCT) state determines the sensitization of Yb(III) luminescence. We propose that this level is populated by the singlet and triplet excited states belonging to pi -> pi* and n -> pi* transitions of both ligands and it can transfer the excitation energy to F-2(5/2)

Impact of intermediate volumes and cell diameters on cell recovery: A predictive model for autologous immunotherapy workflows

CAR-T immunotherapy workflows can vary from process to process and customer to customer. Variables that can alter overall processing efficiency include cell type, cell diameter, input cell numbers, input volumes, final volumes, and number of rinses, among others. These process-specific differences can make it difficult to estimate outputs, and equally challenging to select which processing parameters to use for which workflow. We hypothesized that intermediate processing volumes might vary as the size of the cell diameter increases, to accommodate the larger pellet created during centrifugation and other processing steps. From this, we developed a mathematical model and designed a study to test the validity of our hypothesis. Testing involved using Sepax™ C-Pro CultureWash v432 software to assess the calculated intermediate volume as a function of cell diameter by looking at percent recovery of the harvest. As shown in Equation 1 below, we predict the minimum intermediate volume required for the total number of cells to be function of cell size, total cell number, and an additional 20% buffer volume. Recoveries exceed 88% on a linear range up to 4 billion cells that are ~16 µm in size, where the formula holds true. While recoveries dropped to 68% for larger cell harvests, with a more optimized parameter set (e.g., altered flow rates), we rescued 86% on average for 6 billion cells. In summary, the model and associated data developed on the Sepax™ C-Pro around intermediate volumes provides a framework for future decision-making as scientists develop and adapt workflows to serve novel immunotherapy applications. Future work will address other variables of interest such as additional cell types, pump speed, and larger input cell numbers. Please click Additional Files below to see the full abstract

Ln(III) Complexes Embedded in Biocompatible PLGA Nanoparticles as Potential Vis-to-NIR Optical Probes

In this contribution, we present the spectroscopic study of two NIR emitting hydrophobic heteroleptic (R,R)-YbL1(tta) and (R,R)-NdL1(tta) complexes (with tta = 2-thenoyltrifluoroacetonate and L1 = N,N0 -bis(2-(8-hydroxyquinolinate)methylidene)-1,2-(R,R or S,S)-cyclohexanediamine), both in methanol solution and embedded in water dispersible and biocompatible poly lactic-co-glycolic acid (PLGA) nanoparticles. Thanks to their absorption properties in a wide range of wavelengths extending from the UV up to the blue and green visible regions, the emission of these complexes can be effectively sensitized using visible radiation, which is much less harmful to tissues and skin than the UV one. The encapsulation of the two Ln(III)-based complexes in PLGA allows us to preserve their nature, making them stable in water and to test their cytotoxicity on two different cell lines, with the aim of using them in the future as potential bioimaging optical probes

Near Infared Circularly Polarized Luminescence from water stable organic nanoparticles containing a chiral Yb(III) complex

We report the first example of very efficient NIR Circularly Polarized Luminescence (CPL) (around 970 nm) in water, obtained thanks to the combined use of a chiral Yb complex and of poly lactic-co-glycolic acid (PLGA) nanoparticles. [Yb L (tta) 2 ]CH 3 COO ( L = N, N'-bis(2-pyridylmethylidene)-1,2-( R,R + S,S ) cyclohexanediamine and tta = 2-thenoyltrifluoroacetonate) shows good CPL in organic solvents, because the tta ligands efficiently sensitize Yb NIR luminescence and the readily prepared chiral ligand L endows the complex with the necessary dissymmetry. PLGA nanoparticles incorporate the complex and protect the metal ion from the intrusion of solvent molecules, while ensuring biocompatibility, water solubility and stability to the complex. Hydrophilic NIR-CPL optical probes can find applications in the field of NIR-CPL bio-assays

Circularly Polarized Luminescence from New Heteroleptic Eu(III) and Tb(III) Complexes

The complexes [Eu(bpcd)(tta)], [Eu(bpcd)(Coum)], and [Tb(bpcd)(Coum)] [tta = 2-thenoyltrifluoroacetyl-acetonate, Coum = 3-acetyl-4-hydroxy-coumarin, and bpcd = N,N′-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N′-diacetate] have been synthesized and characterized from photophysical and thermodynamic points of view. The optical and chiroptical properties of these complexes, such as the total luminescence, decay curves of the Ln(III) luminescence, electronic circular dichroism, and circularly polarized luminescence, have been investigated. Interestingly, the number of coordinated solvent (methanol) molecules is sensitive to the nature of the metal ion. This number, estimated by spectroscopy, is >1 for Eu(III)-based complexes and <1 for Tb(III)-based complexes. A possible explanation for this behavior is provided via the study of the minimum energy structure obtained by density functional theory (DFT) calculations on the model complexes of the diamagnetic Y(III) and La(III) counterparts [Y(bpcd)(tta)], [Y(bpcd)(Coum)], and [La(bpcd)(Coum)]. By time-dependent DFT calculations, estimation of donor-acceptor (D-A) distances and of the energy position of the S1and T1ligand excited states involved in the antenna effect was possible. These data are useful for rationalizing the different sensitization efficiencies (ηsens) of the antennae toward Eu(III) and Tb(III). The tta ligand is an optimal antenna for sensitizing Eu(III) luminescence, while the Coum ligand sensitizes better Tb(III) luminescence {φovl= 55%; ηsens≥ 55% for the [Tb(bpcd)(Coum)] complex}. Finally, for the [Eu(bpcd)(tta)] complex, a sizable value of glum(0.26) and a good quantum yield (26%) were measured

Comparative study On The ethical perceptions of contractors and designers in the China construction industry

Ethics is becoming one of the most important requirements for successful business in the 21st century. The construction industry cannot be exceptional from this trend. However construction ethics management requires different approaches from other industries, as the products of the industry are construction projects which are completely different from mass production. Contractors and designers are two major participants in construction projects. The roles and responsibilities of these two project stakeholders decisively influence all aspects of construction project. Practically ethical perceptions of contractors and designers are one of main aspects to be considered for the effective and efficient management of ethics for the construction industry. This research has investigated the ethical perceptions of contractors and designers in the China construction industry. A questionnaire survey which contains 15 ethical issues and 6 demographic factors has been conducted. 170 construction professionals from construction companies and consulting companies have been participated in this survey. These 15 ethical issues are ranked in terms of seriousness, frequency and importance for both contractors and designers as a single group to understand the overall perceptions in the industry. The analysis has also been conducted for contractors and designers respectively to make comparisons between them. The top three serious ethical issues in the industry are ‘Bribery and corruption’, ‘Failure to practice whistle-blowing’ and ‘Improper bidding practices’. Contractors and designers showed similar outcomes for the top five important ethical issues. But for the middle ranged ethical issues, they showed some differences. Further researches are required to identify the causes of the similarity and differences