Search results for "temperature"

Room temperature synthesis of lanthanum phosphates with controlled nanotexture as host for Ln(III) through the Epoxide Route

2022

AbstractHerein, the Epoxide Route, a one-pot room temperature alkalinization method based on the reaction between a nucleophile and an epoxide, has been employed to synthesize LaPO4 in the form of a Rhabdophane phase. The intrinsic features of this synthetic approach allow the reaction to be followed by pH monitoring, making possible the identification of the different precipitation steps involved in the formation of the solid. Once demonstrated the effectiveness of this chemical methodology, the size and shape of the LaPO4 particles were controlled by varying the identity and proportion of the organic co-solvents employed to perform the reaction. By these means, crystalline particles with …

Defying Stereotypes with Nanodiamonds: Stable Primary Diamondoid Phosphines

2016

International audience; Direct unequal C-H bond difunctionalization of phosphorylated diamantane was achieved in high yield from the corresponding phosphonates. Reduction of the functionalized phosphonates provides access to novel primary and secondary alkyl/aryl diamantane phosphines. The prepared primary diamantyl phosphines are quite air stable compared to their adamantyl and especially alkyl or aryl analogues. This finding is corroborated by comparing the singly occupied molecular orbital energy levels of the corresponding phosphine radical cations obtained by density functional theory computations.

Environmental factors influencing the distribution and prevalence of Schistosoma haematobium in school attenders of ILembe and uThungulu Health Distr…

2017

Schistosoma haematobium infection is reported to facilitate the development of urogenital diseases. Its symptoms include haematuria, dysuria and tiredness, and it may cause cognitive decline in children. The prevalence of S. haematobium infection needs to be known in endemic areas and a mass treatment programme against the disease implemented. The aim of this study was to investigate the prevalence and intensity of S. haematobium infection in ILembe and uThungulu health districts, using the major symptom, haematuria, as an indicator. A total of 6 265 urine samples, from 96 rural schools, was collected for analysis using dipsticks. The prevalence of haematuria in the ILembe health district w…

Pyrolytic formation of polycyclic aromatic hydrocarbons from sesquiterpenes

2012

Author's version of an article in the journal: Food Chemistry. Also available from the publisher at: http://dx.doi.org/10.1016/j.foodchem.2012.06.033 The products of the pyrolysis of four sesquiterpenes, β-caryophyllene, α-cedrene, longifolene and valencene, have been examined. Pyrolysis was carried out at 300, 400 and 500 °C, the products determined by GC–MS and then examined for similarities and differences using multivariate data analysis. Analysis showed that longifolene was most resistant and caryophyllene least resistant to pyrolysis with cedrene and valencene occupying intermediate positions. While the compounds were largely unchanged at 300 °C, polycyclic aromatic hydrocarbons (PAHs…

Multi-Chip RFID Antenna Integrating Shape-Memory Alloys for Detection of Thermal Thresholds

2011

Low-cost wireless measurement of objects' temperature is one of the greatest expectation of radiofrequency identification technology for the so many applications in cold supply-chain control and safety assessment in general. In this context, the paper proposes a dual-chip UHF tag embedding shape memory alloys (SMA) able to transform the variation of the tagged item's temperature into a permanent change of antenna radiation features. This event-driven antenna is hence able to selectively activate the embedded microchips according to the temperature above or below a given threshold. A general design methodology for the resulting two-ports tag antenna is here introduced and then applied to pro…

Charge Transport Mechanisms in Heavy-Ion Driven Leakage Current in Silicon Carbide Schottky Power Diodes

2016

Under heavy-ion exposure at sufficiently high reverse bias voltages silicon carbide (SiC) Schottky diodes are observed to exhibit gradual increases in leakage current with increasing ion fluence. Heavy-ion exposure alters the overall reverse current-voltage characteristics of these diodes, leaving the forward characteristics practically unchanged. This paper discusses the charge transport mechanisms in the heavy-ion damaged SiC Schottky diodes. A macro model, describing the reverse current-voltage characteristics in the degraded SiC Schottky diodes is proposed. peerReviewed

Temperature-responsive hybrid nanomaterials based on modified halloysite nanotubes uploaded with silver nanoparticles

2022

New temperature-responsive hybrid nanomaterials based on modified halloysite nanotubes (HNTs) containing grafted polymer brushes with silver nanoparticles have been successfully fabricated. We used a three steps process including synthesis of the initiating coatings onto HNTs surface, fabrication of the POEGMA – poly(oligo(ethylene glycol)ethyl ether methacrylate) grafted brushes and synthesis of the silver nanoparticles (AgNPs). The synthesis and properties of hybrid nanomaterials were studied by FT-IR, TGA and DLS methods. It is shown that the introduction of AgNPs, formed from 0.005 M AgNO3 solution leads to a significant reduction of low critical solution temperature (LCST) of the polym…

Nitrogen-fixing cushion Astragalus siculus modulates soil fertility, microclimate, plant facilitation, bacterial and fungal microbiota along an eleva…

2023

Question: Cushion-forming vascular plants are adapted to alpine environments and act as ecosystem engineers by moderating microclimate and creating a fertility island under their canopy. Most of the available studies on cushion ecology have been devoted to plant facilitation, but none used a holistic approach that considers the response of co-existing plant species with other key ecosystem players. Here, we quantified the biogenic effect and facilitation capacity of Astragalus siculus, a spiny nitrogen-fixing cushion plant, and test the hypothesis that the facilitation effect would increase with elevation as stress gradient.Location: Mount Etna, the highest active volcano in the Mediterrane…

Photosensitive Alternative Splicing of the Circadian Clock Gene timeless Is Population Specific in a Cold-Adapted Fly, Drosophila montana

2018

The evolution of temperature tolerance and invasiveness in a fluctuating thermal environment

2016

The consequences of the climate change on species are still uncertain, despite of intensive research. Currently, rising temperature is not the only concern, since the climate change scenarios also predict increases in the amount of disturbances, such as storms, floods, and thermal fluctuations. Disturbances have also been shown to affect species’ evolution, for example by selecting for traits that are advantageous in fluctuating environments but are also facilitating invasiveness. In this thesis, I study the consequences of evolving in a fluctuating thermal environment by utilizing bacterial microcosms. First I tested the effects of fluctuating vs. constant temperature on the evolution of t…