Coupled Sublattice Melting and Charge-Order Transition in Two Dimensions.

Two-dimensional melting is one of the most fascinating and poorly understood phase transitions in nature. Theoretical investigations often point to a two-step melting scenario involving unbinding of topological defects at two distinct temperatures. Here, we report on a novel melting transition of a charge-ordered K-Sn alloy monolayer on a silicon substrate. Melting starts with short-range positional fluctuations in the K sublattice while maintaining long-range order, followed by longer-range K diffusion over small domains, and ultimately resulting in a molten sublattice. Concomitantly, the charge order of the Sn host lattice collapses in a multistep process with both displacive and order-disorder transition characteristics. Our combined experimental and theoretical analysis provides a rare insight into the atomistic processes of a multistep melting transition of a two-dimensional materials system.

Underdiagnosis of delirium in the elderly in acute care hospital settings: lessons not learned.

BACKGROUND: Delirium is a common and poorly diagnosed cause of behavioral change in elderly. This study aimed to estimate the prevalence, diagnostic accuracy and factors associated with the onset of delirium in the elderly admitted to an urgency unit. METHODS: Cross-sectional study including clinically stable subjects aged ≥60 years between April and June of 2014. Diagnosis of delirium based on the Confusion Assessment Method (CAM, gold standard) was compared to the subjective assessment made by physicians on duty as recorded in the medical chart. Association of sociodemographic, psychological/behavioural, and clinical variables with delirium was assessed using multivariate analysis. RESULTS: A sample of 110 participants with a mean age of 72.7 ± 8.3 years was studied. Of these, 56.4% were men and 28.2% had a diagnosis of delirium on CAM. Significant associations were observed between delirium and male gender (P-value = 0.019), poor or very poor self-perception of health (P-value = 0.033), previous diagnosis of dementia (P-value = 0.001), previous history of stroke (P-value = 0.014), and acute bacterial infection (P-value = 0.008). Physician diagnosis had a sensitivity of 35.5%, specificity of 100%, and accuracy of 81.8% to detect delirium. Rate of misdiagnosis was 64.5%. CONCLUSION: Delirium was underdiagnosed in this urgent care hospital setting.

Genotyping of hepatitis A virus detected in bivalve shellfish in Galicia (NW Spain).

Hepatitis A virus (HAV) represents a significant public health problem due to its high persistence in the environment and its transmission through contaminated water and food. Bivalve shellfish are filter feeders that can bioaccumulate human pathogens found in contaminated waters, their consumption being a potential cause of hepatitis A outbreaks. In this work, cultured and wild bivalve shellfish from the Ría de Vigo (Galicia, NW Spain) were analysed for the presence and genotyping of HAV. A total of 160 shellfish samples were collected between March 2004 and December 2006, including 68 samples from cultured mussels (Mytilus galloprovincialis), 30 from wild clams (Rupitapes decussatus), 31 from wild cockles (Cerastoderma edule) and 31 from wild mussel. HAV detection, carried out by quantitative RT-PCR, was positive for 29 (42.6%) cultured and 40 (43.5%) wild samples, with levels ranging from 3.1 x 10(2) and 1.4 x 10(10) RNA copies/g of shellfish digestive tissue. The phylogenetic analysis of VP1-P2A and VP3-VP1 regions, separately or as concatenated sequences, revealed that all HAV strains analysed belong to subgenotype IB. These results indicate a high prevalence of this subgenotype in the area studied.

Synthesis and study of molecular interactions between phosphatidyl choline and two laminin derived peptides hydrophobically modified.

Two peptides based on the active SIKVAV sequence were synthesized and hydrophobically modified through attachment of a myristoyl residue to the amino terminal group. A comparative study was carried out on the physicochemical properties of both parent and hydrophobically modified structures. Properties studied were hydrophobicity, surface activity, spreadability on aqueous surfaces, penetration in lipid monolayers, aggregation and haemolytic activity. Results obtained indicate that myristoyl containing peptides form micelles at 10(-6) M concentration, whereas parent peptides start to aggregate at 10(-5) M. All of them are able to spread on aqueous surfaces forming stable monolayers. Concerning their haemolytic activity only one of the sequences promotes a partial lysis of erythrocytes after 30 min incubation at 37 degrees C and 10(-5) M concentration in the media.

Pentapeptide YIGSR-mediated HT-1080 fibrosarcoma cells targeting of adriamycin encapsulated in sterically stabilized liposomes.

In the peptide-targeted therapy for cancer, peptides are used to reach a selective and specific target in cancer cells. Peptides are used free or coupled to chemotherapeutic drugs, phagues, proteins, polymers, liposomes, and polymer-grafted liposomes. Using this latter approach, the pentapeptide YIGSR was coupled to the distal end from carboxyl groups of liposome-grafted polyethyleneglycol (PEG) chains (YIGSR-PEG-liposome). As a control, the peptide PEAGD coupled to PEG-liposome was used. The biological activity of YIGSR-PEG-liposome was tested using HT-1080 human fibrosarcoma cells. In adhesion assays, the YIGSR-PEG-liposome coated to plastic plates promoted 30% of the specific cell attachment. In competition assays, YIGSR-PEG-liposome inhibited the specific attachment of cells to laminin-1-coated plates by 25%. Following this, we prepared peptide-PEG-liposomes encapsulating adriamycin (ADR). In vitro cytotoxicity assays against HT-1080 cells gave IC(50) values 2.1 times lower for YIGSR-PEG-liposomal ADR in comparison to PEAGD-PEG-liposomal ADR. The free peptide added in excess increased the IC(50) value of YIGSR-PEG-liposomal ADR by 72%, while the IC(50) value of control liposomal ADR was unaffected, supporting a receptor-mediated mechanism of targeting. In addition, the lower IC(50) value is correlated with a higher total of ADR accumulation in the cells.