CdTe nanoparticles display tropism to core histones and histone-rich cell organelles

The disclosure of the mechanisms of nanoparticle interaction with specific intracellular targets represents one of the key tasks in nanobiology. Unmodified luminescent semiconductor nanoparticles, or quantum dots (QDs), are capable of a strikingly rapid accumulation in the nuclei and nucleoli of living human cells, driven by processes of yet unknown nature. Here, it is hypothesized that such a strong tropism of QDs could be mediated by charge-related properties of the macromolecules presented in the nuclear compartments. As the complex microenvironment encountered by the QDs in the nuclei and nucleoli of live cells is primarily presented by proteins and other biopolymers, such as DNA and RNA, the model of human phagocytic cell line THP1, nuclear lysates, purified protein, and nucleic acid solutions is utilized to investigate the interactions of the QDs with these most abundant classes of intranuclear macromolecules. Using a combination of advanced technological approaches, including live cell confocal microscopy, fluorescent lifetime imaging (FLIM), spectroscopic methods, and zeta potential measurements, it is demonstrated that unmodified CdTe QDs preferentially bind to the positively charged core histone proteins as opposed to the DNA or RNA, resulting in a dramatic shift off the absorption band, and a red shift and decrease in the pholuminescence (PL) intensity of the QDs. FLIM imaging of the QDs demonstrates an increased formation of QD/protein aggregates in the presence of core histones, with a resulting significant reduction in the PL lifetime. FLIM technology for the first time reveals that the localization of negatively charged QDs to their ultimate nuclear and nucleolar destinations dramatically affects the QDs' photoluminescence lifetimes, and offers thereby a sensitive readout for physical interactions between QDs and their intracellular macromolecular targets. These findings strongly suggest that charge-mediated QD/histone interactions could provide the basis for QD nuclear localization downstream of intracellular transport mechanisms.     

A semi-structured clinical interview for the assessment of diagnosis and mental state in the elderly: the Geriatric Mental State Schedule. I. Development and reliability

A standardized, semi-structured interview for examining and recording the mental state in elderly subjects is described. It allows the classification of patients by symptom profile and can demonstrate changes in that profile over time. It is believed that good reliability is demonstrated between psychiatric raters both for psychiatric diagnosis made on the basis of the schedule findings and for individual items. The Geriatric Mental State Schedule (GMS) consists mainly of items from the eighth edition of the PSE (Wing et al. 1967), together with additional items from the PSS (Spitzer et al. 1964), and extra sections dealing with disorientation and other cognitive abnormalities. Modifications have been introduced to facilitate interviewing elderly subjects.     

The hydrolytic stability of glass fiber reinforced poly(butylene terephthalate), poly(ethylene terephthalate) and polycarbonate

The hydrolytic stability of glass fiber reinforced poly(butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET) and polycarbonate (PC) was studied. The activation energies in kcal/mole for hydrolysis are 26 for PBT and 23 for PET. Both PBT and PET contain 30 percent glass fiber reinforcement. The hydrolysis rates for a series of experimental PC's containing 10, 30 and 40 percent glass were obtained from GPC data. These increase with glass concentration but are lower than that of the unreinforced PC. Melt flow rate changes are a good measure of the hydrolytic degradation of PET. However, in the time scale of these experiments, the tensile properties of glass reinforced PBT and PC do not correlate well with M?_w changes, unlike unreinforced PBT and PC polymers. Consequently, to compare these three glass fiber reinforced polymers, estimates of failure time must be based on changes in tensile strength rather than melt flow rate.     

Proteomic and functional characterization of the outer membrane vesicles from the gastric pathogen Helicobacter pylori

The gastric pathogen Helicobacter pylori causes a spectrum of gastro-duodenal diseases, which may be mediated in part by the outer membrane vesicles (OMVs) constitutively shed by the pathogen. We aimed to determine the proteome of H. pylori OMV to help evaluate the mechanisms whereby these structures confer their known immuno-modulatory and cytotoxic activities to host cells, as such disease-associated activities are also conferred by the bacterium from which the vesicles are derived. We also evaluated the effect of the OMV on gastric/colonic epithelial cells, duodenal explants and neutrophils. A proteomic analysis of the OMV proteins separated by SDS-PAGE from two strains of H. pylori (J99 and NCTC 11637) was undertaken and 162 OMV-associated proteins were identified in J99 and 91 in NCTC 11637 by LC-MS/MS. The vesicles are rich in membrane proteins, porins, adhesins and several molecules known to modulate chemokine secretion, cell proliferation and other host cellular processes. Further, the OMVs are also vehicles for the carriage of the cytotoxin-associated gene A cytotoxin in addition to the previously documented toxin, vacuolating cytotoxin. Taken together, it is evident from the proteome of H. pylori OMV that these structures are equipped with the molecules required to interact with host cells in a manner not dissimilar from the intact pathogen.     

The Human Rights Documentation Initiative at the University of Texas Libraries

Human rights documentation presents significant collection, preservation, and access challenges to libraries and archives, activists and advocacy organizations, scholars, and litigators. This article presents a case study of the University of Texas Libraries' Human Rights Documentation Initiative's efforts to address these challenges for web resources and audiovisual born-digital records emerging from human rights conflicts, advocacy, and study. The library's non-custodial partnership with the Kigali Genocide Memorial Centre in Rwanda is used as an example.     

Effects of ausforming temperature on bainite transformation,microstructure and variant selection in nanobainite steel

The bainite transformation behavior after plastic deformation of austenite, i.e., ausforming was studied by in situ neutron diffraction and ex situ experiments, and the effects of ausforming temperature was made clear. Ausforming, at a low temperature (573 K) was found to accelerate bainite transformation and produce a characteristic microstructure, whereas at a high temperature (873 K), ausforming had little influence. The reason for the different results stems from the dislocation structure introduced in austenite; planar dislocations remaining on the active slip planes are believed to assist bainite transformation, accompanied by strong variant selection. The variant selection rule that focuses on Shockley partial dislocation was verified from electron backscatter diffraction results.     

Structure‐Reactivity Studies of Simple 4‐Hydroxyprolinamide Organocatalysts in the Asymmetric Michael Addition Reaction of Aldehydes to Nitroolefins

A series of simple 4‐hydroxyprolinamides was synthesised and they were found to act as organocatalysts for the asymmetric conjugate addition of aldehydes to nitroolefins in excellent yields (98%), with complete diastereoselectivity (99:1, syn:anti) and enantioselectivity (98% ee for syn). Furthermore, the use of low catalyst loadings (5 mol%) and a low aldehyde molar excess (1.5 equivalents) were achieved.     

Work hardening induced by martensite during transformation-induced plasticity in plain carbon steel

Transformation-induced plasticity (TRIP) steels are becoming increasingly exploited for industrial applications because they show high strength and high uniform elongation (ductility). Despite this interest, the relative contributions of the various strengthening and straining mechanisms are often poorly understood. In this study, neutron diffraction is employed to quantify the contribution of different mechanisms to ductility and work hardening for a 0.25 wt.% C steel. Differences in stress–strain response at different temperatures are related to the extent of the transformation of metastable austenite into martensite during deformation. At room temperature (RT) the transformation of austenite occurs gradually with straining, while at ?50 °C the transformation occurs almost from the onset of loading. The associated transformation strain is reduced, comprising nearly half the total strain, lowering the apparent elastic modulus and explaining the relatively low work hardening compared to RT straining. By contrast, deformation at RT after pre-straining at ?50 °C results in larger work hardening than for solely RT straining due to the higher martensite levels introduced at ?50 °C. This is due to composite load transfer to the strong constituent from the soft matrix. The extent of the transformation is quantified as a function of strain at both temperatures as well as its effect on the work hardening and elongation.