53 research outputs found
Synthesis of Trifluoromethyl Ketones via Tandem Claisen Condensation and Retro-Claisen C–C Bond-Cleavage Reaction
A highly
efficient, operationally simple approach to trifluoromethyl
ketones has been developed that builds on the use of a tandem process
involving Claisen condensation and retro-Claisen C–C bond cleavage
reaction. Enolizable alkyl phenyl ketones were found to react readily
with ethyl trifuoroacetate under the promotion of NaH to afford trifluoroacetic
ester/ketone exchange products, trifluoromethyl ketones, which were
quite different from the general Claisen condensation products, β-diketones.
This procedure uses readily available starting materials and can be
extended to the preparation of perfluoroalkyl ketones in excellent
yield
High-Accuracy Peptide Mass Fingerprinting Using Peak Intensity Data with Machine Learning
For MALDI-TOF mass spectrometry, we show that the intensity of a peptide–ion peak is directly correlated with its sequence, with the residues M, H, P, R, and L having the most substantial effect on ionization. We developed a machine learning approach that exploits this relationship to significantly improve peptide mass fingerprint (PMF) accuracy based on training data sets from both true-positive and false-positive PMF searches. The model’s cross-validated accuracy in distinguishing real versus false-positive database search results is 91%, rivaling the accuracy of MS/MS-based protein identification
Hydrothermal Derived LaOF:Ln<sup>3+</sup> (Ln = Eu, Tb, Sm, Dy, Tm, and/or Ho) Nanocrystals with Multicolor-Tunable Emission Properties
A series of LaOF:Ln<sup>3+</sup> (Ln = Eu, Tb, Sm, Dy,
Tm, and/or
Ho) nanocrystals with good dispersion have been successfully prepared
by the hydrothermal method followed a heat-treatment process. Under
ultraviolet radiation and low-voltage electron beam excitation, the
LaOF:Ln<sup>3+</sup> nanocrystals show the characteristic f-f emissions
of Ln<sup>3+</sup> (Ln = Eu, Tb, Sm, Dy, Tm, or Ho) and give red,
blue-green, orange, yellow, blue, and green emission, respectively.
Moreover, there exists simultaneous luminescence of Tb<sup>3+</sup>, Eu<sup>3+</sup>, Sm<sup>3+</sup>, Dy<sup>3+</sup>, Tm<sup>3+</sup>, or Ho<sup>3+</sup> individually when codoping them in the single-phase
LaOF host (for example, LaOF:Tb<sup>3+</sup>, Eu<sup>3+</sup>/Sm<sup>3+</sup>; LaOF:Tm<sup>3+</sup>, Dy<sup>3+</sup>/Ho<sup>3+</sup>;
LaOF:Tm<sup>3+</sup>, Ho<sup>3+</sup>, Eu<sup>3+</sup> systems), which
is beneficial to tune the emission colors. Under low-voltage electron
beam excitation, a variety of colors can be efficiently adjusted by
varying the doping ions and the doping concentration, making these
materials have potential applications in field-emission display devices.
More importantly, the energy transfer from Tm<sup>3+</sup> to Ho<sup>3+</sup> in the LaOF:Tm<sup>3+</sup>, Ho<sup>3+</sup> samples under
UV excitation was first investigated and has been demonstrated to
be a resonant type via a quadrupole-quadrupole mechanism. The critical
distance (<i>R</i><sub>Tm–Ho</sub>) is calculated
to be 28.4 Ă…. In addition, the LaOF:Tb<sup>3+</sup> and LaOF:Tm<sup>3+</sup> phosphors exhibit green and blue luminescence with better
chromaticity coordinates, color purity, and higher intensity compared
with the commercial green phosphor ZnO:Zn and blue phosphor Y<sub>2</sub>SiO<sub>5</sub>:Ce<sup>3+</sup> to some extent under low-voltage
electron beam excitation
Luminescence and Energy Transfer Properties of Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl and Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl:A (A = Eu<sup>2+</sup>/Ce<sup>3+</sup>/Dy<sup>3+</sup>/Tb<sup>3+</sup>) under UV and Low-Voltage Electron Beam Excitation
Pure Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl and rare earth ion (Eu<sup>2+</sup>/Ce<sup>3+</sup>/Dy<sup>3+</sup>/Tb<sup>3+</sup>) doped Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl phosphors with the apatite
structure have been prepared via a Pechini-type sol–gel process.
X-ray diffraction (XRD) and structure refinement, photoluminescence
(PL) spectra, cathodoluminescence (CL) spectra, absolute quantum yield,
as well as lifetimes were utilized to characterize samples. Under
UV light excitation, the undoped Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl sample shows broad band photoluminescence
centered near 480 nm after being reduced due to the defect structure.
Eu<sup>2+</sup> and Ce<sup>3+</sup> ion doped Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl samples also show broad 5d
→ 4f transitions with cyan and blue colors and higher quantum
yields (72% for Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl:0.04Eu<sup>2+</sup>; 67% for Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl:0.016Ce<sup>3+</sup>). For Dy<sup>3+</sup> and Tb<sup>3+</sup> doped Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl samples, they give strong line emissions coming from
4f → 4f transitions. Moreover, the Ce<sup>3+</sup> ion can
transfer its energy to the Tb<sup>3+</sup> ion in the Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl host, and the energy
transfer mechanism has been demonstrated to be a resonant type, via
a dipole–quadrupole interaction. However, under the low voltage
electron beam excitation, Tb<sup>3+</sup> ion doped Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl samples present different
luminescence properties compared with their PL spectra, which is ascribed
to the different excitation mechanism. On the basis of the good PL
and CL properties of the Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl:A (A = Ce<sup>3+</sup>/Eu<sup>2+</sup>/Tb<sup>3+</sup>/Dy<sup>3+</sup>), Ca<sub>2</sub>Ba<sub>3</sub>(PO<sub>4</sub>)<sub>3</sub>Cl might be promising for application in solid state lighting
and field-emission displays
Labeling Lysosomes and Tracking Lysosome-Dependent Apoptosis with a Cell-Permeable Activity-Based Probe
In this study, we describe a new strategy for labeling
and tracking
lysosomes with a cell-permeable fluorescent activity-based probe (CpFABP)
that is covalently bound to select lysosomal proteins. Colocalization
studies that utilized LysoTracker probes as standard lysosomal markers
demonstrated that our novel probe is effective in specifically labeling
lysosomes in various kinds of live cells. Furthermore, our studies
revealed that this probe has the ability to label fixed cells, permeabilized
cells, and NH<sub>4</sub>Cl-treated cells, unlike LysoTracker probes,
which show ineffective labeling under the same conditions. Remarkably,
when applied to monitor the process of lysosome-dependent apoptosis,
our probe not only displayed the expected release of lysosomal cathepsins
from lysosomes into the cytosol but also revealed additional information
about the location of the cathepsins during apoptosis, which is undetectable
by other chemical lysosome markers. These results suggest a wide array
of promising applications for our probe and provide useful guidelines
for its use as a lysosome marker in lysosome-related studies
Blue Emitting Ca<sub>8</sub>La<sub>2</sub>(PO<sub>4</sub>)<sub>6</sub>O<sub>2</sub>:Ce<sup>3+</sup>/Eu<sup>2+</sup> Phosphors with High Color Purity and Brightness for White LED: Soft-Chemical Synthesis, Luminescence, and Energy Transfer Properties
Ce<sup>3+</sup> and/or Eu<sup>2+</sup> activated Ca<sub>8</sub>La<sub>2</sub>(PO<sub>4</sub>)<sub>6</sub>O<sub>2</sub> (CLPA)
oxyapatite
blue phosphors have been prepared via a Pechini-type sol–gel
process. X-ray diffraction (XRD), photoluminescence (PL) spectra,
absolute quantum yield, as well as lifetimes were utilized to characterize
samples. The emission of Ce<sup>3+</sup> and Eu<sup>2+</sup> ions
at different lattice sites has been identified and discussed. The
CLPA:0.04Ce<sup>3+</sup> phosphor exhibits bright blue emission with
higher quantum yield (67%) and excellent CIE coordinates (<i>x</i> = 0.160, <i>y</i> = 0.115) under UV excitation,
and the CLPA:0.05Eu<sup>2+</sup> phosphor also exhibits blue emission
with CIE coordinates (0.187, 0.164). The energy transfer from Ce<sup>3+</sup> to Eu<sup>2+</sup> in CLPA:Ce<sup>3+</sup>/Eu<sup>2+</sup> phosphors has been validated and demonstrated to be a resonant type
via a dipole–dipole mechanism. The critical distance (<i>R</i><sub>c</sub>) of Ce<sup>3+</sup> to Eu<sup>2+</sup> ions
in CLPA was calculated (by the spectral overlap method) to be 26.67
Ă…. The quantum yields of Ce<sup>3+</sup> and Eu<sup>2+</sup> coactivated
CLPA phosphors are enhanced compared with that of Eu<sup>2+</sup> activated
samples due to energy transfer. The CIE coordinates of CLPA:0.04Ce<sup>3+</sup>, 0.02Eu<sup>2+</sup> are (0.179, 0.169). The corresponding
luminescence and energy transfer mechanisms have been proposed in
detail. These blue phosphors might be promising for use in pc-white
LEDs
Spontaneous, local diastolic subsarcolemmal calcium releases in single, isolated guinea-pig sinoatrial nodal cells
<div><p>Uptake and release calcium from the sarcoplasmic reticulum (SR) (dubbed “calcium clock”), in the form of spontaneous, rhythmic, local diastolic calcium releases (LCRs), together with voltage-sensitive ion channels (membrane clock) form a coupled system that regulates the action potential (AP) firing rate. LCRs activate Sodium/Calcium exchanger (NCX) that accelerates diastolic depolarization and thus participating in regulation of the time at which the next AP will occur. Previous studies in rabbit SA node cells (SANC) demonstrated that the basal AP cycle length (APCL) is tightly coupled to the basal LCR period (time from the prior AP-induced Ca<sup>2+</sup> transient to the diastolic LCR occurrence), and that this coupling is further modulated by autonomic receptor stimulation. Although spontaneous LCRs during diastolic depolarization have been reported in SANC of various species (rabbit, cat, mouse, toad), prior studies have failed to detect LCRs in spontaneously beating SANC of guinea-pig, a species that has been traditionally used in studies of cardiac pacemaker cell function. We performed a detailed investigation of whether guinea-pig SANC generate LCRs and whether they play a similar key role in regulation of the AP firing rate. We used two different approaches, 2D high-speed camera and classical line-scan confocal imaging. Positioning the scan-line beneath sarcolemma, parallel to the long axis of the cell, we found that rhythmically beating guinea-pig SANC do, indeed, generate spontaneous, diastolic LCRs beneath the surface membrane. The average key LCR characteristics measured in confocal images in guinea-pig SANC were comparable to rabbit SANC, both in the basal state and in the presence of β-adrenergic receptor stimulation. Moreover, the relationship between the LCR period and APCL was subtended by the same linear function. Thus, LCRs in guinea-pig SANC contribute to the diastolic depolarization and APCL regulation. Our findings indicate that coupled-clock system regulation of APCL is a general, species-independent, mechanism of pacemaker cell normal automaticity. Lack of LCRs in prior studies is likely explained by technical issues, as individual LCRs are small stochastic events occurring mainly near the cell border.</p></div
Image_4_Is there a causal association between gestational diabetes mellitus and immune mediators? A bidirectional Mendelian randomization analysis.tif
BackgroundDiabetes that only appears or is diagnosed during pregnancy is referred to as gestational diabetes mellitus (GDM). The maternal physiological immune profile is essential for a positive pregnancy outcome. However, the causal relationship between GDM and immunophenotypes is not fully defined.MethodsBased on the high-density genetic variation data at the genome-wide level, we evaluated the logical associations between 731 specific immune mediators and GDM using bidirectional Mendelian randomization (MR). The inverse variance weighted (IVW) was the main method employed for MR analysis. We performed multiple methods to verify the robustness and dependability of the MR results, and sensitivity measures were applied to rule out potential heterogeneity and horizontal pleiotropy.ResultsA substantial causal association between several immune mediators and GDM was detected. After FDR testing, HLA DR++ monocyte %leukocyte and HLA DR on plasmacytoid DC were shown to increase the risk of GDM; in contrast, CD127 on CD28+ CD45RA+ CD8br and CD19 on PB/PC were shown to attenuate the effect of GDM. Moreover, the progression of GDM has been shown to decrease the maternal levels of CD39+ activated Treg AC, CD39+ activated Treg �4 Treg, CD39+ resting Treg AC, CD39+ resting Treg �4 Treg, and CD39+ CD8BR %T cell.ConclusionsOur findings support a possible causal association between GDM and various immunophenotypes, thus facilitating the provision of multiple options for preventive recognition as well as for the diagnostic and therapeutic management of GDM in clinical practice.</p
Secondary clustering of LIHC patients in TCGA based on the expression of NCLs.
(A) Tumor samples were divided into four subgroups. (B) Correlation plots between the four subgroups and the high & low risk categories. (C) Survival curves for four subgroups. (D-G) PCA and t-SNE analyses of four subgroups. (H-J) Immune cell infiltration in four subgroups.</p
Table_4_Is there a causal association between gestational diabetes mellitus and immune mediators? A bidirectional Mendelian randomization analysis.xlsx
BackgroundDiabetes that only appears or is diagnosed during pregnancy is referred to as gestational diabetes mellitus (GDM). The maternal physiological immune profile is essential for a positive pregnancy outcome. However, the causal relationship between GDM and immunophenotypes is not fully defined.MethodsBased on the high-density genetic variation data at the genome-wide level, we evaluated the logical associations between 731 specific immune mediators and GDM using bidirectional Mendelian randomization (MR). The inverse variance weighted (IVW) was the main method employed for MR analysis. We performed multiple methods to verify the robustness and dependability of the MR results, and sensitivity measures were applied to rule out potential heterogeneity and horizontal pleiotropy.ResultsA substantial causal association between several immune mediators and GDM was detected. After FDR testing, HLA DR++ monocyte %leukocyte and HLA DR on plasmacytoid DC were shown to increase the risk of GDM; in contrast, CD127 on CD28+ CD45RA+ CD8br and CD19 on PB/PC were shown to attenuate the effect of GDM. Moreover, the progression of GDM has been shown to decrease the maternal levels of CD39+ activated Treg AC, CD39+ activated Treg �4 Treg, CD39+ resting Treg AC, CD39+ resting Treg �4 Treg, and CD39+ CD8BR %T cell.ConclusionsOur findings support a possible causal association between GDM and various immunophenotypes, thus facilitating the provision of multiple options for preventive recognition as well as for the diagnostic and therapeutic management of GDM in clinical practice.</p
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