Planting Design in the Ecuadorian Andes: Memory,Resilience, and Re-Connection

Modern cities are constantly growing and evolving. This expansion of urban development bleeds into the surrounding landscapes, causing the displacement and disturbance of native plant and animal species to remote areas where topography limits human access. As a result, metropolitan areas often become gray places with low biodiversity, elevated temperatures, poor air quality, flood issues, and lack of a local identity. Quito, Ecuador is one of the cities facing this important challenge. Perched high in the Andes, Quito is a place of great biodiversity, nevertheless the constructed landscapes are dominated by introduced species due to colonization and to the lack of availability of native species in the nursery trade. This article walks through the creation of a native nursery in Quito and the implementation of initial trial plots, a green roof, and a garden. It explains the discoveries made during the process and provides directions for future goals to reintroduce native plant species into urban environments and contemporary landscapes in order to create more sustainable cities. The goal is to help people reconnect with their natural heritage and to learn about native plants to ensure the continuity of ancestral knowledge of the natural world for future generations.     

Electrodeposited zinc oxide thin films: Nucleation and growth mechanism

The nucleation and growth mechanism of the electrodeposited zinc oxide thin films on fluorine-doped tin oxide (FTO) coated (10–20 Ω/cm²) glass substrates from acetate solution, without and with ex situ oxygen bubbling, has been studied by cyclic voltammetry (CV), chronoamperometry (CA) and scanning electron microscopy (SEM) techniques. Ethylene diamine tetra acetic acid (EDTA) was used as a complexing agent. The cyclic voltammograms exhibit crossover, a characteristic of nucleation process on FTO-coated conducting glass substrates for all the baths bubbled with oxygen. The current transients were analyzed by fitting chronoamperometric data into the Scharifker–Hills nucleation model. The plausible nucleation and growth mechanism is proposed. For mother bath and lower oxygen bubbling time, the nucleation and growth mechanism follows 3D progressive nucleation and growth, which became instantaneous in case of baths for higher oxygen bubbling time. The SEM study showed that the films become compact when the oxygen bubbling time was increased. The thin films were further characterized by X-ray diffraction technique for structural studies and the ZnO film formation was confirmed. With the increase in oxygen bubbling time, the shift in band gap energies from 3.2 to 3.3 eV is observed.     

Detection of Therapeutic Levels of Ionizing Radiation Using Plasmonic Nanosensor Gels

Radiotherapy is a highly complex and efficient treatment modality for ablation of malignant tumors. Despite several technological advances, determination of the dose delivered to the tumor remains a challenge due to limitations of complex fabrication, cumbersome operation, and high costs associated with current dosimeters. This study describes fundamental studies and development of a novel gel‐based colorimetric nanosensor for detecting therapeutic levels of X‐rays (1–10 Gy) administered in clinical radiotherapy. Following exposure to X‐rays, gold salts in the gel are converted to nanoparticles within the matrix, resulting in the formation of a maroon‐colored plasmonic gel. Differences in color intensity of the gel following irradiation are used as a quantitative indicator of the radiation dose employed. The gel‐based nanosensor is able to detect doses as low as 0.5 Gy, and demonstrates a linear detection range of 0–3 Gy, which indicates its application in the fractionated radiotherapy regime. The gel is also able to successfully report therapeutic levels of radiation doses administered to anthropomorphic tissue phantoms. The range of detection, ease of fabrication, simplicity of colorimetric detection, and relatively lower costs indicate that this technology can be potentially translated to different radiotherapy applications in the clinic.     

The spin trap reagent PBN attenuates degeneration of 5-HT neurones in rat brain induced by p-chloroamphetamine but not fenfluramine

Dark Agouti rats injected with either p-chloroamphetamine (PCA; 2.5 mg/kg i.p.) or fenfluramine (15 mg/kg i.p.) had substantial decreases (approximately 50%) in the concentration of 5-HT and 5-HIAA and binding of [3H]paroxetine in the cerebral cortex 7 days later. This indicates that both compounds had produced neurodegeneration of 5-HT axon terminals. Two doses of alpha-phenyl-N-tert-butyl nitrone (PBN; 150 mg/kg i.p.) 130 min apart had no effect on cortical 5-HT content or [3H]paroxetine binding. However, when PBN (150 mg/ kg) was given 10 min before and 120 min after PCA (2.5 mg/kg) it attenuated the PCA-induced neurodegeneration. In contrast, PBN was without significant effect on the fenfluramine-induced damage. Changes in rectal temperature following either the neurotoxins or neurotoxins+ PBN were no more than +/-1 degree C of saline-injected control rats. These data indicate that PCA, like MDMA, probably induces neurotoxic degeneration because of the formation of catechol or quinone metabolites and subsequent reactive tree radical formation. Such a mechanism does not appear to explain fenfluramine-induced damage to 5-HT neurones.     

HIV-specific lymphoproliferative responses in asymptomatic HIV-infected individuals

In vitro lymphoproliferative responses to HIV-1 recombinant antigens (gp160, p24, and Rev protein) were studied in 83 patients with asymptomatic HIV-1 infection (CDC groups II and III) and circulating CD4 lymphocyte numbers > 400/mm3. Significant response to at least one of the three antigens was detected in 52.4% of the subjects, but the responses were weak, and concordance of the response to the three antigens was rare, the frequency of individuals responding to each antigen not exceeding 22.4%. Increasing frequencies of response were observed when recall antigens (tetanus toxoid and Candida albicans glycomannoprotein) (65.5%) and anti-CD3 MoAb (76.6%) were used as stimuli. Although a significant association between lymphocyte response to p24, but not gp160, and steadiness of CD4 lymphocyte numbers before the assay was observed, no predictive value for lack of CD4 cell decrease was confirmed for either antigen, and fluctuation of the responses to HIV antigens was seen during subsequent follow up. The panel of T cell assays used could be regarded as appropriate for monitoring both HIV-specific responses and T lymphocyte function during immunotherapy with soluble HIV antigens.     

Mathematical modelling, simulation and prediction of tumour-induced angiogenesis

Angiogenesis, the formation of blood vessels from a pre-existing vasculature, is a process whereby capillary sprouts are formed in response to externally supplied chemical stimuli. The sprouts then grow and develop, driven by endothelial cell migration and proliferation, and organise themselves into a dendritic structure. Angiogenesis occurs during embryogenesis, wound healing, arthritis and during the growth of solid tumours. In this paper we present a novel mathematical model which describes the formation of the capillary sprout network in response to chemical stimuli (tumour angiogenesis factors, TAF) supplied by a solid tumour. The model also takes into account endothelial cell-extracellular matrix interactions via the inclusion of fibronectin in the model. The model consists of a system of nonlinear partial differential equations describing the response in space and time of endothelial cells to the TAF and the fibronectin (migration, proliferation, anastomosis, branching). Using the discretized system of partial differential equations, we use a deterministic cellular automata (DCA) model, which enables us to track individual endothelial cells and incorporate branching explicity into the model. Numerical simulations are presented which are in very good qualitative agreement with experimental observations. Certain experiments are suggested which could be used to test the hypotheses of the model and various extensions and developments of the model with particular applications to anti-angiogenesis strategies are discussed.