6,589 research outputs found
Characteristics And Temporal Variations Of Organic And Elemental Carbon Aerosols In A High–Altitude, Tropical Latin American Megacity
Bogota is a Latin American megacity located at an average altitude of 2600 m in the tropical Andes. It registers frequent episodes of poor air quality due to high PM10 concentrations. The carbonaceous fraction is the main PM10 component (>50%), but there is a lack of specific studies analyzing the characteristics and temporal variability of organic carbon (OC) and elemental carbon (EC) aerosols. In this study, daily samples (24±1h) were collected from June 2015 to May 2016 (a total of 308 samples) at an urban background site during an El Niño year, and the quartz filters were analyzed using a thermal-optical method. Results showed that EC and organic matter accounted for ~60% of the PM10 mass. The OC and EC averages were 8.92 ± 4.52 μg/m3 and 3.25 ± 1.59 μg/m3, respectively. The months with the highest average OC values were January to March, while EC concentrations were relatively constant throughout the year. Regarding daily values, the highest mean concentrations of OC (10.2 ± 5.13 μg/m3) and EC (3.73 ± 1.74 μg/m3) were obtained on Thursdays, and the lowest on Sundays (OC = 6.67 ± 3.04 μg/m3 and EC = 2.46 ± 0.94 μg/m3). The OC/EC ratio ranged from 1.66 (June) to 4.88 (March), with an annual average of 3.16 ± 2.01. The secondary organic carbon (SOC) contributions, measured using the EC-tracer method, accounted for 45% of the total OC. The effective carbon ratio, which indicates an association between carbonaceous particles and climate change, ranged from 0.12 (July) to 0.74 (May). The study of air-mass origins revealed that days with air mass from E + NE registered the highest OC concentrations. This research provides new data on the variability of carbonaceous aerosols over the course of a year. It also highlights forest fires as a significant source of OC and EC, and indicates the high impact of SOC on OC concentration at the sampling site
Power Quality Monitoring Integration into Distribution Automation through the Use of AMR
Power-quality events are of increasing concern for the
economy because today’s equipment, particularly computers and
automated manufacturing devices, is highly sensitive to such
imperfections. With volatile energy rates and a need to control
costs, regional agencies and utilities are interested in technologies
to meter distribution use and manage utility information.
Metering technologies and communications systems have
advanced to enable the development of Automated Meter Reading
(AMR) Systems. Power Quality is one area where the AMR
system can be very valuable. This paper investigates the
challenges in the development of distributed power-quality
monitoring system. The approach of this paper is divided into
metering, data collection, archiving, analysis, and presentation. It
also discusses system architecture, implementation, and provides
general guidelines in the tailoring of PQ indexes. This paper
describes the challenges and lessons learned from this work.
Thiol precursors in Catarratto Bianco Comune and Grillo grapes and effect of clarification conditions on the release of varietal thiols in wine
Background and aims: Varietal thiols characterize the typical aroma of several white wines, as Sauvignon blanc. Their presence was suggested in two Sicilian grape cultivars, Catarratto Bianco Comune (CBC) and Grillo, thought it was not analytically proved to date.
Methods and Results: Varietal thiol precursors and free varietal thiols were assessed in CBC and Grillo grapes, musts and wines by UPLC/high resolution mass spectrometry (HRMS). The isobaric compounds S-3-(hexanal)-glutathione (GSH-3MHAl) and S-3-(4-mercapto-4-methylpentan-2-one)-glutathione (GSH-4MMP) were discriminated by comparing their accurate masses and HR-MS/MS spectra with those of their synthetic standards. GSH-3MHAl, S-3-(hexan-1-ol)-glutathione (GSH-3MH) and S-3-(hexan-1-ol)-cysteine occurred in grape, must and wine, while GSH-4MMP and its hydrolysed forms did not. Their amounts decreased during the industrial winemaking processes, mostly following the grape pressing. We compared clarification conditions exposing must to either air or CO2 in terms of thiol precursors\u2019 and free thiols\u2019 content in wine. However, negligible differences were observed. Concentrations of free thiols in the range 400\u20131100 ng/L were found in the wines and they were not affected to the two clarification conditions adopted.
Conclusion: The isobaric GSH-3MHAl and GSH-4MMP were clearly distinguished for the first time by UPLC-HRMS through their retention times and MS spectra. The varietal thiols were firstly revealed CBC and Grillo wines. The air-free and air- exposed clarification poorly affected the levels of varietal thiols.
Significance of the study: This research highlights the major impact of the varietal thiols (mainly 3\u2013mercapto-hexan-1-ol and its acetate form) on the sensory properties of CBC and Grillo wines
Nanocarriers for topical delivery of resveratrol.
Purpose: The aim of the present work was to develop a nanocarrier-based formulation for topical delivery of resveratrol.
Methods: Trans-resveratrol (t-res) was encapsulated in liposomes, ethosomes or transferosomes, by a modified hand-shaking method followed by extrusion. All the formulations were characterised in terms of mean diameter, size distribution (I.P.), t-res loading, t-res stability upon encapsulation during storage. The nanocarriers containing t-res were then introduced in cellulose-based gel to allow their final administration on the skin and the viscoelastic properties of the resulting formulation were investigated. Finally, we studied the inhibition of reactive oxygen species (ROS) in human keratinocyte (HaCaT) cell line stimulated with H2O2 for 24 h and then incubated with the t-res containing nanocarriers.
Results: All the t-res containing carriers were characterised by a very high (close to 100%) encapsulation efficiency, a negligible t-res release at 4°C and stability of resveratrol in its trans form. The carriers only slightly influenced the viscoelastic characteristics of cellulose-based gels. Nanocarriers encapsulating t-res reduced, in a concentration-dependent manner, ROS production induced by H2O2 and this effect was higher when using t-res-encapsulating nanocarrier, with the higher effect observed in the case of ethosomes.
Conclusions: In this work nanocarriers with high encapsulation efficiency, high physical stability and negligible t-res release during storage at 4°C were prepared. To allow their final administration on the skin, the nanocarrier can be easilisy loaded in cellulose-based gels without altering its rheological properties. Moreover, the use of t-res-encapsulating ethosomes led to an efficient antioxidant activity. Further ex vivo and in vivo studies will clarify the role of the different carrier when administered on the skin
Cross-reaction of naturally-produced β-lactamases from Citrobacter farmeri and Citrobacter amalonaticus with immunological detection of CTX-M enzymes.
The NG-Test CTX-M MULTI immunochromatographic assay has been developed to identify CTX-M-type β-lactamases in Enterobacterales, being the most widespread extended-spectrum β-lactamases. We showed here that the chromosomally-encoded ß-lactamases from Citrobacter farmeri and Citrobacter amalonaticus generated false-positive NG-Test CTX-M MULTI results, compromising the specificity of the test
Physicochemical Characterization And Sources Of The Thoracic Fraction Of Road Dust In A Latin American Megacity
Road dust has been identified as one of the main sources of outdoor PM10 in Bogota (a Latin American megacity), but there are no studies that have analyzed the physicochemical characteristics and origins of its respirable fraction. A characterization of inorganic compounds (water soluble ions, major and trace elements, organic and elemental carbon) and an analysis of source contributions to the PM10 fraction of road dust were carried out in this study. A total of twenty road dust samples, selected from representative industrial, residential and commercial areas, were swept and resuspended to obtain the thoracic fraction. Size distribution by laser diffraction and individual particle morphology by Scanning Electron Microscopy were also evaluated. The data obtained revealed that the volume (%) of thoracic particles was higher in samples from industrial zones where heavy vehicular traffic, industrial emissions and deteriorated pavements predominated. Crustal elements were the most abundant species, accounting for 49–62% of the thoracic mass, followed by OC (13–29%), water-soluble ions (1.4–3.8%), EC (0.8–1.9%) and trace elements (0.2–0.5%). The Coefficient of Divergence was obtained to identify the spatial variability of the samples. A source apportionment analysis was carried out considering the variability of chemical profiles, enrichment factors and ratios of Fe/Al, K/Al, Ca/Al, Ti/Al, Cu/Sb, Zn/Sb, OC/TC and OC/EC. By means of a PCA analysis, five components were identified, including local soils and pavement erosion (63%), construction and demolition activities (13%), industrial emissions (6%), brake wear (5%) and tailpipe emissions (4%). These components accounted for 91% of the total variance. The results provide data to understand better one of the main sources of PM10 emissions in Bogota, such as road dust. These data will be useful to optimize environmental policies, and they may be used in future studies of human health and air quality modeling
Bronchoscopic balloon dilatation in the management of bronchial stenosis following lung transplantation
SummaryBackgroundBronchial stenosis (BS) is currently found in 7–15% of lung transplantation (LT) recipients. Current treatment strategies have included Nd:Yag laser, cryotherapy, bougie dilatation and stent placement. Bronchoscopic balloon dilatation has been used as alternative treatment in a few cases with controversial results. This is a study to prospectively assess the efficacy of bronchoscopic balloon dilatation as a first step in the management of post-LT BS.MethodsFrom January 1995 to December 2002, bronchoscopic balloon dilatation was evaluated as first therapeutic option in all consecutive LT patients with BS. Symptoms, pulmonary function tests, airway diameter and use of other therapeutic techniques were evaluated.ResultsA total of 10 out of 284 anastomed airways (3.5%) in 9 out of 152 LT patients were included in the study and follow-up lasted from 6 to 81 months. Dilatation of all but one BS met with initial success: increase of both luminal dimensions and forced vital capacity (P=0.01), and relief of symptoms. Bronchoscopic balloon dilatation long-term follow-up showed effective results in 5 out of 10 (50%) bronchial stenoses, after an average of 4 bronchoscopic balloon dilatation procedures (range 1–8). No severe complications were observed. Stent placement was required in the other 5 bronchial stenoses.ConclusionsBronchoscopic balloon dilatation is a safe method that should be considered as first therapeutic treatment of post-LT BS. Its use avoids the need for stent placement in up to 50% of cases
Total organic carbon, total nitrogen and chemical characteristics of an haplic cambisol after biochar incorporation
Biochar
has
been
used
as
a
soil
conditioner
to
increase
the
soil
organic
carbon
content
and
to
improve
the
soil
chemical
characteristics.
However,
the
effect
of
biochar
on
soil
is
still
not
clear
and
the
soil
type
and
biochar
composition
should
also
play
an
important
role.
In
this
context,
the
main
objective
of
this
work
was
to
evaluate
the
effect
of
biochar
application
on
the
organic
carbon
(C)
content
and
on
chemical
characteristics
of
subtropical
Cambisol.
The
field
experiment
was
located
at
the
State
University
of
Centro
‐
Oeste
in
Irati,
Brazil,
and
the
soil
was
classified
as
an
Haplic
Cambisol
(Embrapa,
1999).
The
applied
biochar
was
composed
mainly
by
fine
residues
(
70%
<
2mm
)
of
an
eucalyptus
biochar
that
was
a
waste
of
the
local
steel
industry.
In
February
2010,
four
increasing
doses
of
biochar
were
applied
to
the
soil
(T1
‐
0
t
ha
‐
1
;
T2
‐
10
t
ha
‐
1
;
T3
‐
20
t
ha
‐
1
and
T4
‐
40
t
ha
‐
1
)
with
four
replicates.
Soil
samples
were
composed
by
three
subsamples
collected
within
each
plot.
Biochar
was
applied
on
the
soil
surface
and
thereafter
it
was
incorporated
into
a
0
‐
10
cm
soil
depth
with
an
harrow.
Soil
samples
were
collected
in
September
2011
at
four
soil
depths:
0
‐
5;
5
‐
10;
10
‐
20
and
20
‐
30
cm.
The
samples
were
air
dried
and
passed
through
a
2
mm
sieve.
Soil
C
and
nitrogen
(N)
contents
were
determined
by
dry
combustion
and
the
soil
characteristics
assessed
were:
pH
in
water,
available
P,
exchangeable
K,
Ca,
Mg
and
Al,
potential
acidity
(H
+
Al),
cation
exchange
capacity
(CEC),
effective
cation
exchange
capacity
(ECEC)
and
base
saturation
(V%)
(Tedesco
et
al.,
1995).
The
mean
values
were
compared
using
SAS
software
(Tukey
10%).
The
main
alterations
in
soil
characteristics
were
observed
in
the
superficial
depth
(0
‐
5
cm)
(Table
1)
probably
due
to
the
permanence
of
the
biochar
fine
particles
at
the
soil
surface.
In
this
layer,
the
application
of
40
t
ha
‐
1
of
biochar
(treatment
T4)
increased
in
15.5
g
kg
‐
1
the
C
content
in
comparison
to
treatment
T1.
The
treatments
T2
and
T3
also
increased
the
C
content,
but
the
differences
were
not
significant.
N
content
was
not
affected
by
biochar
application.
The
highest
dose
of
biochar
(treatment
T4)
promoted
an
increase
of
the
C/N
ratio
from
12
to
16
at
the
0
‐
5
cm
depth.
Treatment
T4
also
increased
the
soil
pH
value
in
comparison
to
treatment
T1.
In
addition,
the
contents
of
available
P,
exchangeable
K
and
Ca
where
higher
under
treatment
T4
in
comparison
to
treatment
T1
(Table
1).
In
opposition,
exchangeable
Mg
content,
Al+H,
V%
and
CEC
were
not
altered
by
any
treatment,
but
T4
increased
the
ECEC
in
3.1
cmol
c
dm
‐
3
in
comparison
to
T1.
The
results
observed
are
probably
due
the
high
C
and
ash
(26,5%)
contents
of
biochar.
A
contribution
of
the
functional
groups
on
the
surface
of
the
biochar
to
the
ECEC
should
not
be
excluded
(Sparkes
&
Stoutjesdijk,
2011).
Our
results
indicate
that
after
two
years
of
biochar
application
an
increase
of
soil
organic
carbon
and
a
positive
impact
on
the
soil
chemical
characteristics
at
the
soil
surface
were
attained,
but
only
with
the
highest
tested
dose
(40
t
ha
‐
1
)
.Peer reviewe
Effect of biochar amendment on morphology, productivity and water relations of sunflower plants under non-irrigation conditions
páginas.-- 6 figuras.-- 2 tablas.-- 56 referencias.-- Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.catena.2016.07.037.Three biochars (B1: pine wood, B2: paper-sludge, B3: sewage-sludge) produced under controlled pyrolysis conditions and one produced in kilns (B4: grapevine wood) were used as organic ameliorants in a Calcic Cambisol, which represents a typical agricultural soil of the Mediterranean region. This field study was performed with plants of sunflower (Helianthus annuus L.) at the experimental station “La Hampa”, located in the Guadalquivir river valley (SW Spain). The soil was amended with doses equivalent to 1.5 and 15 t ha− 1 of the four biochars in two independent plantations. In addition, un-amended plots were prepared in both experiments for comparison purposes. The major goal of this study was the assessment of the effect of biochar amendment on the physiology and development of sunflower plants at field conditions. During most of the growing period plants of un-amended and amended plots showed no stress symptoms either by their appearance or by stress-sensitive biochemical parameters such as the stability of the photosystem II (QY). Biochar addition had no effect on seed germination. Addition of 1.5 t ha− 1 biochar did not significantly change the pH of the soil, its electrical conductivity (EC) or its water holding capacity (WHC). Concomitantly the plant development and plant biomass production remained unaltered. Amendments with 15 t ha− 1 slightly increased the WHC of the soil but showed no lasting impact on the soil pH. It stimulated plant growth and led to a greater leaf area, larger plant stems and wider inflorescences of the sunflower plants than those cultivated on the un-amended soil. At the end of the experiment, biochar amendment of soil caused no significant increase of the total biomass production excepting B4, the biochar with the lowest capacity of water retention, which exhibited the highest vegetative growth and seed production. The lack of rain during the last weeks caused a water shortage in the culture that produced greater QY loss in non-amended plants. Interestingly, better growth of amended plants during the drought period correlated with higher reduction of stomatal conductance, indicating that the greater water use efficiency is at the origin of the better crop performance of biochar-amended plants. This finding points to the agronomic relevance of biochar amendment of Mediterranean rain fed crops.The Marie Skłodowska-Curie actions of the European Union's FP7 People Programme (REA grant agreement no PCIG12-GA-2012-333784-Biocharisma project) and the Spanish Ministry of Economy and Competitiveness (MINECO) (project PCGL2012-37041) are thanked for the financial support of the present study. The Spanish Ministry of Education, Culture and Sport is acknowledged for funding the FPU fellowship (FPU 13/05831) of Marina Paneque, and the contract of Juan De Dios Franco-Navarro (AGL2009-08339/AGR). The European Biochar Network (Biochar as option for sustainable resource management-COST action TD1107) and Bodegas Torres (Spain) are acknowledged for providing the biochar samples. M. Velasco is gratefully acknowledged for her technical assistance at field.Peer reviewe
Trichinella britovi etiological agent of sylvatic trichinellosis in the Republic of Guinea (West Africa) and a re-evaluation of geographical distribution for encapsulated species in Africa
In West Africa, Trichinella infection was documented in humans and animals from Senegal in the 1960s, and the biological characters of one isolate showed a lower infectivity to domestic pigs and rodents when compared with that of a Trichinella spiralis pig isolate from Europe. To identify the Trichinella species present in West Africa, a survey was conducted in a total of 160 wild animals in the Republic of Guinea. Three Viverridae, one true civet (Viverra civetta) and two African palm civets (Nandinia binotata) from the Fouta Djallon Massif, Pilimini Subprefecture, were found positive by artificial digestion of muscle samples. Trichinella larvae from these three viverrids were identified as Trichinella britovi and no difference was detected in three examined sequences from these African isolates and the reference strain of T. britovi from Europe, indicating common ancestry, an historically continuous geographic distribution, and recent isolation for African and European populations. The detection of T. britovi in West Africa modifies our knowledge about the distribution of encapsulated species of Trichinella in Africa. Thus, Trichinella nelsoni is now considered to have a distribution limited to the Eastern part of the Afrotropical region from Kenya to South Africa. This provides a plausible explanation for the presence of Trichinella T8 in Namibia and South Africa, and further suggests that T. britovi could be the Trichinella species circulating among wild animals of Northern Africa
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