Remote sensing phenology at European northern latitudes - From ground spectral towers to satellites

Plant phenology exerts major influences on carbon, water, and energy exchanges between atmosphere and ecosystems, provides feedbacks to climate, and affects ecosystem functioning and services. Great efforts have been spent in studying plant phenology over the past decades, but there are still large uncertainties and disputations in phenology estimation, trends, and its climate sensitivities. This thesis aims to reduce these uncertainties through analyzing ground spectral sampling, developing methods for in situ light sensor calibration, and exploring a new spectral index for reliable retrieval of remote sensing phenology and climate sensitivity estimation at European northern latitudes. The ground spectral towers use light sensors of either nadir or off-nadir viewing to measure reflected radiation, yet how plants in the sensor view contribute differently to the measured signals, and necessary in situ calibrations are often overlooked, leading to great uncertainties in ground spectral sampling of vegetation. It was found that the ground sampling points in the sensor view follow a Cauchy distribution, which is further modulated by the sensor directional response function. We proposed in situ light sensor calibration methods and showed that the user in situ calibration is more reliable than manufacturer’s lab calibration when our proposed calibration procedures are followed. By taking the full advantages of more reliable and standardized reflectance, we proposed a plant phenology vegetation index (PPI), which is derived from a radiative transfer equation and uses red and near infrared reflectance. PPI shows good linearity with canopy green leaf area index, and is correlated with gross primary productivity, better than other vegetation indices in our test. With suppressed snow influences, PPI shows great potentials for retrieving phenology over coniferous-dominated boreal forests. PPI was used to retrieve plant phenology from MODIS nadir BRDF-adjusted reflectance at European northern latitudes for the period 2000-2014. We estimated the trend of start of growing season (SOS), end of growing season (EOS), length of growing season (LOS), and the PPI integral for the time span, and found significant changes in most part of the region, with an average rate of -0.39 days·year-1 in SOS, 0.48 days·year-1 in EOS, 0.87 days·year-1 in LOS, and 0.79%·year-1 in the PPI integral over the past 15 years. We found that the plant phenology was significantly affected by climate in most part of the region, with an average sensitivity to temperature: SOS at -3.43 days·°C-1, EOS at 1.27 days·°C-1, LOS at 3.16 days·°C-1, and PPI integral at 2.29 %·°C-1, and to precipitation: SOS at 0.28 days∙cm-1, EOS at 0.05 days∙cm-1, LOS at 0.04 days∙cm-1, and PPI integral at -0.07%∙cm-1. These phenology variations were significantly related to decadal variations of atmospheric circulations, including the North Atlantic Oscillation and the Arctic Oscillation. The methods developed in this thesis can help to improve the reliability of long-term field spectral measurements and to reduce uncertainties in remote sensing phenology retrieval and climate sensitivity estimation

Aqua­(2,6-dihy­droxy­benzoato-κO 1)bis­(1,10-phenanthroline-κ2 N,N′)manganese(II) 2,6-dihy­droxy­benzoate hemihydrate

In the complex cation of the title compound, [Mn(C7H5O4)(C12H8N2)2(H2O)](C7H5O4)·0.5H2O, the MnII atom has a six-coordinate octa­hedral environment defined by one carboxyl­ate O atom belonging to a 2,6-dihy­droxy­benzoate (DHB) ligand, four N atoms from two chelating 1,10-phenanthroline mol­ecules and one water mol­ecule. The lattice water mol­ecule lies on a twofold rotation axis. Intra­molecular O—H⋯O hydrogen bonds are present in the DHB anions and complex cations. Inter­molecular O—H⋯O hydrogen bonds link two cations, two anions and one water mol­ecule into a dimer. π–π inter­actions between the pyridine and benzene rings and between the benzene rings are also observed [centroid–centroid distances = 3.7774 (16), 3.7912 (16) and 3.7310 (17) Å]

Bis(2,6-dihy­droxy­benzoato-κ2 O 1,O 1′)(nitrato-κ2 O,O′)bis­(1,10-phenanthroline-κ2 N,N′)neodymium(III)

In the mononuclear title complex, [Nd(C7H5O4)2(NO3)(C12H8N2)2], the NdIII atom is in a distorted bicapped square-anti­prismatic geometry formed by four N atoms from two chelating 1,10-phenanthroline (phen) ligands, four O atoms from two 2,6-dihy­droxy­benzoate (DHB) ligands and two O atoms from a nitrate anion. π–π stacking inter­actions between the phen and DHB ligands of adjacent complexes [centroid–centroid distances = 3.520 (6) and 3.798 (6) Å] stabilize the crystal structure. Intra­molecular O—H⋯O hydrogen bonds are observed in the DHB ligands

Bis(2,6-dihy­droxy­benzoato-κ2 O 1 ,O 1′)(nitrato-κ2 O,O′)bis­(1,10-phenanthroline-κ2 N,N′)samarium(III)

The title mononuclear complex, [Sm(C7H5O3)2(NO3)(C12H8N2)2], is isostructural with that of other lanthanides. The Sm atom is in a pseudo-bicapped square-anti­prismatic geometry, formed by four N atoms from two chelating 1,10-phenanthroline (phen) ligands and by six O atoms, four from two 2,6-dihy­droxy­benzoate (DHB) ligands and the other two from a nitrate anion. π–π stacking inter­actions between phen and DHB ligands [centroid–centroid distance = 3.528 (4) and 3.812 (3) Å], and phen and phen ligands [face-to-face separation = 3.420 (10) Å] of adjacent complexes stabilize the crystal structure. Intra­molecular O—H⋯O hydrogen bonds are observed in the DHB ligands

Bis(2,6-dihy­droxy­benzoato-κ2 O 1 ,O 1′)(nitrato-κ2 O,O′)bis­(1,10-phenanthroline-κ2 N,N′)europium(III)

The title mononuclear complex, [Eu(C7H5O3)2(NO3)(C12H8N2)2], is isostructural with those of other lanthanides. The Eu atom is in a pseudo-bicapped square-anti­prismatic geometry, formed by four N atoms from two chelating 1,10-phenanthroline (phen) ligands and by six O atoms, four from two 2,6-dihy­droxy­benzoate (DHB) ligands and the other two from a nitrate anion. π–π stacking inter­actions between phen and DHB ligands [centroid–centroid distances = 3.5312 (19) and 3.8347 (16) Å], and between phen and phen ligands [face-to-face separation = 3.433 (4) Å] of adjacent complexes stabilize the crystal structure. Intra­molecular O—H⋯O hydrogen bonds are observed in the DHB ligands

Bis(2,6-dihy­droxy­benzoato-κ2 O 1,O 1′)(nitrato-κ2 O,O′)bis­(1,10-phenanthroline-κ2 N,N′)dysprosium(III)

In the mononuclear title complex, [Dy(C7H5O4)2(NO3)(C12H8N2)2], the DyIII atom is in a distorted bicapped square-anti­prismatic geometry formed by four N atoms from two chelating 1,10-phenanthroline (phen) ligands, four O atoms from two 2,6-dihy­droxy­benzoate (DHB) ligands and two O atoms from a nitrate anion. Inter­molecular π–π stacking inter­actions between the phen and DHB ligands [centroid–centroid distances = 3.542 (4) and 3.879 (4) Å] and between the pyridine and benzene rings of adjacent phen ligands [centroid–centroid distance = 3.751 (4) Å] stabilize the crystal structure. Intra­molecular O–H⋯O hydrogen bonds are observed in the DHB ligands

Bis(2,6-dihy­droxy­benzoato-κ2 O 1,O 1′)(nitrato-κ2 O,O′)bis­(1,10-phenanthroline-κ2 N,N′)praseodymium(III)

The mononuclear title complex, [Pr(C7H5O3)2(NO3)(C12H8N2)2], is isostructural with related complexes of other lanthanides. The Pr(III) atom is in a pseudo-bicapped square-anti­prismatic geometry, formed by four N atoms from two chelating 1,10-phenanthroline (phen) ligands and six O atoms, four from two 2,6-dihy­droxy­benzoate (DHB) ligands and the other two from nitrate anions. π–π stacking inter­actions between the phen and DHB ligands [centroid–centroid distances = 3.518 (2) and 3.778 (2) Å] and the phen and phen ligands [face-to-face separation = 3.427 (6) Å] of adjacent complexes stabilize the crystal structure. Intra­molecular O—H⋯O hydrogen bonds are observed in the DHB ligands

Diaqua­(2,6-dihy­droxy­benzoato-κ2 O 1 ,O 1′)bis­(2,6-dihy­droxy­benzoato-κO 1)bis­(1,10-phenanthroline-κ2 N,N′)lanthanum(III)–1,10-phenanthroline (1/1)

In the title compound, [La(C7H5O4)3(C12H8N2)3(H2O)2]·C12H8N2, the LaIII atom is coordinated by four N atoms from two chelating 1,10-phenanthroline (phen) ligands, four O atoms from three 2,6-dihy­droxy­benzoate (DHB) anions (one monodentate, the other bidentate) and two water O atoms, completing a distorted LaN4O6 bicapped square-anti­prismatic geometry. Within the mononuclear complex mol­ecule, intra­molecular π–π stacking inter­actions are observed, the first between a coordinated phen mol­ecule and a DHB ligand [centroid–centroid distance = 3.7291 (16) Å], and the second between a coordinated phen mol­ecule and an uncoordinated phen ligand [centroid–centroid distance = 3.933 (2) Å]. Inter­molecular π–π stacking is observed between adjacent complexes [inter­planar distance = 3.461 (3) Å]. Intra- and inter­molecular O—H⋯O hydrogen bonds are observed in the DHB ligands and between a water mol­ecule and DHB ligands, respectively. O—H⋯N hydrogen bonds are also observed in the DHB ligands and between uncoordinated phen mol­ecules and aqua ligands

Bis(2,6-dihy­droxy­benzoato-κ2 O 1 ,O 1′)(nitrato-κ2 O,O′)bis­(1,10-phenanthroline-κ2 N,N′)gadolinium(III)

In the mononuclear title complex, [Gd(C7H5O3)2(NO3)(C12H8N2)2], the Gd atom is in a pseudo-bicapped square-anti­prismatic geometry formed by four N atoms from two chelating 1,10-phenanthroline (phen) ligands and by six O atoms, four from two 2,6-dihy­droxy­benzoate (DHB) ligands and the other two from a nitrate anion. π–π stacking inter­actions between phen–DHB [centroid–centroid distances = 3.5334 (18) and 3.8414 (16) Å] and phen–phen [face-to-face separation = 3.4307 (17) Å] ligands of adjacent complex molecules stabilize the crystal structure. Intra­molecular O—H⋯O hydrogen bonds are observed in the DHB ligands

Brucella Dysregulates Monocytes and Inhibits Macrophage Polarization through LC3-Dependent Autophagy

Brucellosis is caused by infection with Brucella species and exhibits diverse clinical manifestations in infected humans. Monocytes and macrophages are not only the first line of defense against Brucella infection but also a main reservoir for Brucella. In the present study, we examined the effects of Brucella infection on human peripheral monocytes and monocyte-derived polarized macrophages. We showed that Brucella infection led to an increase in the proportion of CD14++CD16− monocytes and the expression of the autophagy-related protein LC3B, and the effects of Brucella-induced monocytes are inhibited after 6 weeks of antibiotic treatment. Additionally, the production of IL-1β, IL-6, IL-10, and TNF-α from monocytes in patients with brucellosis was suppressed through the LC3-dependent autophagy pathway during Brucella infection. Moreover, Brucella infection inhibited macrophage polarization. Consistently, the addition of 3-MA, an inhibitor of LC3-related autophagy, partially restored macrophage polarization. Intriguingly, we also found that the upregulation of LC3B expression by rapamycin and heat-killed Brucella in vitro inhibits M2 macrophage polarization, which can be reversed partially by 3-MA. Taken together, these findings reveal that Brucella dysregulates monocyte and macrophage polarization through LC3-dependent autophagy. Thus, targeting this pathway may lead to the development of new therapeutics against Brucellosis