Herein, a single-step
production for the development of gas sensing
devices from unsubstituted and hexadecafluorinated metal phthalocyanines
(MPc, M = Fe2+ and Co2+) is explained. The preparation
of sensor devices by the direct growth of nanowires on interdigitated
electrodes by the vapor transport of the synthesized MPc precursors
is discussed, emphasizing a single-step approach. Results using as-prepared
devices for the detection of NH3 and NO2 in
the ppb range are shown. In agreement with similar MPc sensing materials,
response and recovery times fitted using a double-exponential model
gave two rate constants: a short one, on the order of minutes for
concentrations above 500 ppb, and a long one, on the order of hours.
These rate constants are suitable for environmental monitoring of
gases in recovery zones, where longer exposure times are critical
in the sampling process. Our F16FePc-NW sensor prototypes
show a ∼10% normalized response toward NH3 at 40
ppb for a measuring time of ∼2.5 h at room temperature and
measurable responses to concentrations as low as 5 ppb, rendering
them applicable to environmental studies.
Aim
Assess climatic risk to vegetation types associated with tropical and temperate ecosystems based on exposure analysis, which models future risk as a function of deviation from current climate variable distributions.
Location
Oaxaca State, Mexico.
Taxon
Broadly defined vegetation types used in state‐ and national‐level vegetation classification systems. These types can be grouped into series representing dry‐to‐wet conditions for tropical and temperate vegetation.
Methods
We used climate exposure analysis to compare current and future climate parameters for the major vegetation types of Oaxaca. This technique integrates a recent vegetation map with historical climate data (1981–2010) to produce a baseline climate layer that is compared to climate projections made with five different global circulation models for near‐future (2015–2039) and end‐century (2075–2099) periods using two emissions scenarios (RCP 4.5 and 8.5). We classified the frequency distribution of the baseline climate into five exposure classes where the closer values are to mean climate conditions, the lower the exposure. Future exposure was estimated by classifying the vegetation pixels into the same exposure classes, now based on future climate values. Increased exposure risk was assessed based on the fraction of pixels that moved into higher exposure classes from one period to another.
Results and main conclusions
Our analysis showed four general trends: (a) the higher, current track emissions scenario produced much larger end‐century climate exposure; (b) for the tropical vegetation series, tropical evergreen forests are projected as most exposed by end‐century; (c) for the temperate vegetation series the matorral‐shrubland and conifer forests are the most impacted; and (d) the five GCMs considered showed some convergence in their end‐century climate exposure predictions, with coastal and low‐elevation areas of the State projected to experience the greatest exposure, and the interior mountain slopes and central region projected to experience the least exposure and be the most climatically stable.
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