Urban modernization and heritage in the historic centre of Santiago de Chile (1818–1939)

ABSTRACT

Architecture and urban heritage have been decisive in the modernization of the historical centre of Santiago de Chile. As early as the first half of the nineteenth century they added value to this area of the capital. Public authorities, with the support of regulations, identified valuable urban heritage, incorporating it into urban transformations. For various practical or historical reasons, buildings and public spaces were preserved and eventually reused, giving birth to a renewed idea of planning, which took advantage of this existing heritage. The incorporation of new typologies into the colonial urban fabric, together with the conservation of traditional buildings and public spaces, produced memorable places, both in the republican and modern city. They enriched the urban practices and the city landscapes, offering a valuable continuity with the colonial and republican past. The integration of old and new stimulated the emergence of an urbanism of quality. This article focuses on three specific moments of that peculiar modernization process: the consolidation of the original colonial grid (1818–1846), Vicuña Mackenna’s Transformation Plan (1872–1875) and Santiago's first official Urbanization Plan (1939).     

Gas sensing properties of columnar CeO2 nanostructures prepared by chemical vapor deposition

Columnar CeO2 nanostructures are grown on alumina substrates by a template- and catalyst-free Chemical Vapor Deposition (CVD) approach and subsequently tested as resistive gas sensors of CH3COCH3, H2, NO2. The sensor response is stable and reproducible throughout the whole working temperature range (200-500 degrees C) and directly dependent on the analyte gas and the adopted operating conditions. The higher sensitivity with respect to that displayed by continuous CeO2 thin films demonstrates the potential of fabricating nanostructured sensing devices characterized by improved functional performances.     

Phase behavior of binary and ternary blends of poly(styrene‐co‐methacrylic acid), poly(styrene‐co‐4‐vinylpyridine), and poly(2,6‐dimethyl‐1,4‐phenylene oxide)

Poly(styrene‐co‐methacrylic acid) (PSMA) and poly(styrene‐co‐4‐vinylpyridine) (PS4VP) of different compositions were prepared and characterized. The phase behavior of these copolymers as binary PSMA/PS4VP mixtures or with poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) as PPO/PSMA or PPO/PS4VP and PPO/PSMA/PS4VP ternary blends was investigated by differential scanning calorimetry (DSC). This study showed that PPO was miscible with PS4VP containing up to 15 mol % 4‐vinylpyridine (4VP) but immiscible with PS4VP‐30 (where the number following the hyphen refers to the percentage 4VP in the polymer) and PSMA‐20 (where the number following the hyphen refers to the percentage methacrylic acid in the polymer) over the entire composition range. To examine the morphology of the immiscible blends, scanning electron microscopy was used. Because of the hydrogen‐bonding specific interactions that occurred between the carboxylic groups of PSMA and the pyridine groups of PS4VP, chloroform solutions of PSMA‐20 and PS4VP‐15 formed interpolymer complexes. The obtained glass‐transition temperatures (T_g's) of the PSMA‐20/PS4VP‐15 complexes were found to be higher than those calculated from the additivity rule. Although, depending on the content of 4VP, the shape of the T_g of the PPO/PS4VP blends changed from concave to S‐shaped in the case of the miscible blends, two T_g were observed with each PPO/PS4VP‐30 and PPO/PS4VP‐40 blend. The thermal stability of the PSMA‐20/PS4VP‐15 interpolymer complexes was studied by thermogravimetry. On the basis of the obtained results, the phase behavior of the ternary PPO/PSMA‐20/PS4VP‐15 blends was investigated by DSC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Volatile components of several virgin and refined oils differing in their botanical origin

BACKGROUND: The volatile components of virgin and refined oils whose compositions were very different in terms of oleic, linoleic and linolenic acyl groups were studied by solid phase microextraction (SPME) followed by gas chromatography/mass spectrometry (GC/MS), and their composition of acyl groups was determined by proton nuclear magnetic resonance ¹H NMR. The virgin oils studied were olive, linseed and walnut oils, while the refined oils were sunflower and rapeseed oils. RESULTS: Large differences were found among the headspace compositions of the virgin oils. These were due in part to compounds that could be considered as markers of different vegetable origins and manufacturing processes, but also to compounds resulting from degradative oxidation of the main acyl group components. By virtue of their being refined, fewer components were present in the refined oils, although differences in their headspaces were found owing to the presence of compounds resulting from oxidation of the determined acyl groups. CONCLUSION: The studied oils show specific characteristics regarding not only their main components, which are well known, but also their volatile components. The latter provide information on some of the processes to which oils have been submitted, on their oxidation level, on their botanical origin and on the compounds responsible for their odour. Copyright © 2011 Society of Chemical Industry     

Identifying irradiated oysters by luminescence techniques (TL & PSL)

This study shows an exhaustive comparison of different methods, based on luminescence techniques, to identify X-ray irradiated oysters at five different dose levels in the range 0.1-2 kGy and suggests a simple, fast and sequential routine analysis protocol. A total number of 50 oysters from North Sea, including 10 control samples, were analysed by using two photo-stimulated luminescence (PSL) methods (named A and B) and three thermoluminescence (TL) methods (named C, D and E), either on constituents or contaminating minerals from shells and intestines. Setting a lower threshold value T1 (1000 counts/60s) all of control specimens gave negative screening results while photo counts from irradiated samples were found to be higher than upper threshold T2 (4000 counts/60s), except at the lowest dose level 0.1 kGy for procedure A. All PSL calibrated analysis were successful and a sensitivity index was also determined to better classify obtained data according to the revised European Standard (EN 13751:2009). TL ratios, Glow 1 over second Glow 2, the latter after irradiating at 1 kGy and remeasuring the same minerals for each sample, showed values less than 0.1 related to untreated samples or higher than 0.1 for irradiated ones. Reported procedures were also tested over 60 days, longer than oyster shelf life confirming the applicability and feasibility of the proposed methods.     

Nanopatterning of Anionic Nanoparticles based on Magnetic Prussian‐Blue Analogues

Prussian‐blue analogues (PBA) are a family of molecule‐based magnetic compounds of general formula A_xM_y[M’(CN)₆]_z, whose magnetic properties can be tuned by an external stimulus. This tunability makes PBA good candidates for their integration into new electronic or spintronic devices. As a previous step to accomplish this integration, PBA need to be deposited onto surfaces in controllable ways and if possible into specific positions on the surface. Even though the study of PBA has traditionally been limited to bulk, lately they have also been processed as nanoparticles (NPs). Here an efficient approach is presented for the accurate deposition and organization of PBA‐NPs of different sizes (from ～6 to ～25 nm) over silicon surfaces. The approach used in this work, relies on a combination of surface functionalization with local oxidation nanolithography (LON) and uses electrostatic interactions between PBA‐NPs and a charged self‐assembled monolayer patterned on specific parts of the silicon surface. By using atomic force microscopy (AFM), magnetometry, infrared spectroscopy (IR) and auger electron spectroscopy (AES) we show that the deposition process does not affect NPs properties. In addition, we present a study on the evolution of AFM nanolithographed SiO₂ patterns under sonication.     

Titanium Surface Characteristics Induce the Specific Reprogramming of Toll-like Receptor Signaling in Macrophages

Most of the research on titanium-based dental implants (Ti-discs) is focused on how they are able to stimulate the formation of new tissue and/or cytotoxic studies, with very scarce data on their effects on functional responses by immunocompetent cells. In particular, the link between the rewiring of innate immune responses and surface biomaterials properties is poorly understood. To address this, we characterize the functional response of macrophage cultures to four different dental titanium surfaces (MA: mechanical abrasion; SB + AE: sandblasting plus etching; SB: sandblasting; AE: acid etching). We use different Toll-like receptor (TLR) ligands towards cell surface receptors (bacterial lipopolysaccharide LPS for TLR4; imiquimod for TLR7; synthetic bacterial triacylated lipoprotein for TLR2/TLR1) and endosomal membrane receptor (poly I:C for TLR3) to simulate bacterial (cell wall bacterial components) or viral infections (dsRNA and ssRNA). The extracellular and total LDH levels indicate that exposure to the different Ti-surfaces is not cytotoxic for macrophages under resting or TLR-stimulated conditions, although there is a tendency towards an impairment in macrophage proliferation, viability or adhesion under TLR4, TLR3 and TLR2/1 stimulations in SB discs cultures. The secreted IL-6 and IL-10 levels are not modified upon resting macrophage exposure to the Ti-surfaces studied as well as steady state levels of iNos or ArgI mRNA. However, macrophage exposure to MA Ti-surface do display an enhanced immune response to TLR4, TLR7 or TLR2/1 compared to other Ti-surfaces in terms of soluble immune mediators secreted and M1/M2 gene expression profiling. This change of characteristics in cellular phenotype might be related to changes in cellular morphology. Remarkably, the gene expression of Tlr3 is the only TLR that is differentially affected by distinct Ti-surface exposure. These results highlight the relevance of patterned substrates in dental implants to achieve a smart manipulation of the immune responses in the context of personalized medicine, cell-based therapies, preferential lineage commitment of precursor cells or control of tissue architecture in oral biology.     

Ag/ZnO nanomaterials as high performance sensors for flammable and toxic gases

Ag/ZnO nanocomposites supported on polycrystalline Al2O3 were synthesized by an unprecedented approach combining plasma enhanced chemical vapor deposition (PE-CVD) of ZnO matrices and the subsequent deposition of Ag nanoparticles (NPs) by radio frequency (RF) sputtering. The system structure, composition and morphology were investigated by glancing incidence x-ray diffraction (GIXRD), secondary ion mass spectrometry (SIMS), field emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy (EDXS). A tailored dispersion and distribution of silver particles could be obtained under mild conditions by the sole variation of the sputtering time. Gas sensing properties toward flammable and toxic gases, both reducing (CH3CH2OH, CH3COCH3) and oxidizing (O3), were investigated in the temperature range 100-400?°C. Beside the high sensitivity, the developed sensors exhibited a response proportional to Ag content, thanks to catalytic and electronic effects promoted by silver NPs. In addition, discrimination between oxidizing and reducing analytes was enabled by a suitable choice of the adopted working temperature.     

Role of Biliverdin Reductase A in the Regulation of Insulin Signaling in Metabolic and Neurodegenerative Diseases: An Update

Insulin signaling is a conserved pathway that orchestrates glucose and lipid metabolism, energy balance, and inflammation, and its dysregulation compromises the homeostasis of multiple systems. Insulin resistance is a shared hallmark of several metabolic diseases, including obesity, metabolic syndrome, and type 2 diabetes, and has been associated with cognitive decline during aging and dementia. Numerous mechanisms promoting the development of peripheral and central insulin resistance have been described, although most of them were not completely clarified. In the last decades, several studies have highlighted that biliverdin reductase-A (BVR-A), over its canonical role in the degradation of heme, acts as a regulator of insulin signaling. Evidence from human and animal studies show that BVR-A alterations are associated with the aberrant activation of insulin signaling, metabolic syndrome, liver steatosis, and visceral adipose tissue inflammation in obese and diabetic individuals. In addition, recent findings demonstrated that reduced BVR-A levels or impaired BVR-A activation contribute to the development of brain insulin resistance and metabolic alterations in Alzheimer’s disease. In this narrative review, we will provide an overview on the literature by focusing on the role of BVR-A in the regulation of insulin signaling and how BVR-A alterations impact on cell dysfunctions in both metabolic and neurodegenerative disorders.     

Molecular Features and Diagnostic Challenges in Alpha/Beta T-Cell Large Granular Lymphocyte Leukemia

Large granular lymphocyte leukemia is a rare chronic lymphoproliferative disease of cytotoxic lymphocytes. The diagnosis, according to the WHO, is based on a persistent (>6 months) increase in the number of LGL cells in the peripheral blood without an identifiable cause. A further distinction is made between T-LGL and NK-LGL leukemia. The molecular sign of LGL leukemia is the mutation of STAT3 and other genes associated with the JAK/STAT pathway. The most common clinical features are neutropenia, anemia, and thrombocytopenia, and it is often associated with various autoimmune conditions. It usually has an indolent course. Due to the rarity of the disease, no specific treatment has yet been identified. Immunosuppressive therapy is used and may allow for disease control and long-term survival, but not eradication of the leukemic clone. Here, we discuss the clinical presentation, diagnostic challenges, pathophysiology, and different treatment options available for alpha/beta T-LGL leukemia, which is the most common disease (85%), in order to better understand and manage this often misunderstood disease.