116 research outputs found
Involvement Matters
This project examines how parentsâ past educational experiences affect how they help their children at home with literacy. To conduct this study, I sent home open-ended surveys to parents in my second grade classroom that pertain to parentsâ knowledge, beliefs, and how they contribute to their current involvement with their childrenâs literacy activities at home. Along with the survey, I interviewed second grade students with open-ended questions to uncover their perception of interactions and involvement of their parents at home. Analysis uncovered common themes across the data. Previous literature shows that there is a connection between parent involvement and studentâs achievement; however, literature is limited to parentsâ past experiences and their involvement
Enzyme-Responsive Snap-Top Covered Silica Nanocontainers
Mesoporous silica nanoparticles, capable of storing a payload of small molecules and releasing it following specific catalytic activation by an esterase, have been designed and fabricated. The storage and release of the payload is controlled by the presence of [2]rotaxanes, which consist of tri(ethylene glycol) chains threaded by α-cyclodextrin tori, located on the surfaces of the nanoparticles and terminated by a large stoppering group. These modified silica nanoparticles are capable of encapsulating guest molecules when the [2]rotaxanes are present. The bulky stoppers, which serve to hold the tori in place, are stable under physiological conditions but are cleaved by the catalytic action of an enzyme, causing dethreading of the tori and release of the guest molecules from the pores of the nanoparticles. These snap-top covered silica nanocontainers (SCSNs) are prepared by a modular synthetic method, in which the stoppering unit, incorporated in the final step of the synthesis, may be changed at will to target the response of the system to any of a number of hydrolytic enzymes. Here, the design, synthesis, and operation of model SCSNs that open in the presence of porcine liver esterase (PLE) are reported. The empty pores of the silica nanoparticles were loaded with luminescent dye molecules (rhodamine B), and stoppering units that incorporate adamantyl ester moieties were then attached in the presence of α-cyclodextrin using the copper-catalyzed azideâalkyne cycloaddition (CuAAC), closing the SCSNs. The release of rhodamine-B from the pores of the SCSN, following PLE-mediated hydrolysis of the stoppers, was monitored using fluorescence spectroscopy
Sunitinib Inhibits Cell Proliferation and Alters Steroidogenesis by Down-Regulation of HSD3B2 in Adrenocortical Carcinoma Cells
The multi-tyrosine kinase inhibitor sunitinib is used in the treatment of several solid tumors. Animal experiments pointed to an adrenotoxic effect of sunitinib. Therefore, we evaluated the expression of key targets of sunitinib in human adrenocortical carcinoma (ACC) tumor samples and investigated its in vitro effects in ACC cell lines. We carried out immunohistochemistry for vascular endothelial growth factor (VEGF) and its receptor (VEGF-R2) in 157 ACC samples and nine normal adrenal glands. VEGF and VEGF-R2 protein were expressed in 72 and 99% of ACC samples, respectively. Using NCI-H295 and SW13 ACC cell lines, we investigated the effects of sunitinib on cell proliferation. Sunitinib reduced dose-dependently cell viability of both NCI-H295 and SW13 cells (SW13: 0.1âÎŒM 96â±â7%, 1âÎŒM 90â±â9%*, 5âÎŒM 62â±â6%*, controls 100â±â9%; *pâ<â0.05). To determine sunitinib effects on steroidogenesis, we measured steroid hormones in cell culture supernatant by gas chromatographyâmass spectrometry. We observed a pronounced decrease of cortisol secretion (1âÎŒM 90.1â±â1.5%*, 5âÎŒM 57.2â±â0.3%*, controls 100â±â2.4%) and a concomitant increase in the DHEA/4-androstenedione and 17-hydroxypregnenolone/17-hydroxyprogesterone ratios, indicating specific inhibition of 3ÎČ-hydroxysteroid dehydrogenase (HSD3B2). In yeast microsomes transformed with HSD3B2, no direct inhibition of HSD3B2 by sunitinib was detected. Sunitinib induced down-regulation of HSD3B2 mRNA and protein in ACC cell lines (mRNA: 1âÎŒM 44â±â16%*; 5âÎŒM 22â±â2%*; 10âÎŒM 19â±â4%*; protein: 1âÎŒM 82â±â8%; 5âÎŒM 63â±â8%*; 10âÎŒM 55â±â9%*). CYP11B1 was down-regulated at mRNA but not at protein level and CYP11A1 remained unchanged. In conclusion, target molecules of sunitinib are expressed in the vast majority of ACC samples. Sunitinib exhibits anti-proliferative effects in vitro, and appears to specifically block adrenal steroidogenesis by down-regulation of HSD3B2, rendering it a promising option for treatment of ACC
Peripheral halo-functionalization in [Cu(N^N)(P^P)]+ emitters: influence on the performances of light-emitting electrochemical cells
A series of heteroleptic [Cu(N^N)(P^P)][PF6] complexes is described in which P^P = bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos) and N^N = 4,4âČ-diphenyl-6,6âČ-dimethyl-2,2âČ-bipyridine substituted in the 4-position of the phenyl groups with atom X (N^N = 1 has X = F, 2 has X = Cl, 3 has X = Br, 4 has X = I; the benchmark N^N ligand with X = H is 5). These complexes have been characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analyses and cyclic voltammetry; representative single crystal structures are also reported. The solution absorption spectra are characterized by high energy bands (arising from ligand-centred transitions) which are red-shifted on going from X = H to X = I, and a broad metal-to-ligand charge transfer band with λmax in the range 387â395 nm. The ten complexes are yellow emitters in solution and yellow or yellow-orange emitters in the solid-state. For a given N^N ligand, the solution photoluminescence (PL) spectra show no significant change on going from [Cu(N^N)(POP)]+ to [Cu(N^N)(xantphos)]+; introducing the iodo-functionality into the N^N domain leads to a red-shift in λmaxem compared to the complexes with the benchmark N^N ligand 5. In the solid state, [Cu(1)(POP)][PF6] and [Cu(1)(xantphos)][PF6] (fluoro-substituent) exhibit the highest PL quantum yields (74 and 25%, respectively) with values of Ï1/2 = 11.1 and 5.8 ÎŒs, respectively. Light-emitting electrochemical cells (LECs) with [Cu(N^N)(P^P)][PF6] complexes in the emissive layer have been tested. Using a block-wave pulsed current driving mode, the best performing device employed [Cu(1)(xantphos)]+ and this showed a maximum luminance (Lummax) of 129 cd mâ2 and a device lifetime (t1/2) of 54 h; however, the turn-on time (time to reach Lummax) was 4.1 h. Trends in performance data reveal that the introduction of fluoro-groups is beneficial, but that the incorporation of heavier halo-substituents leads to poor devices, probably due to a detrimental effect on charge transport; LECs with the iodo-functionalized N^N ligand 4 failed to show any electroluminescence after 50 h
Scaling K2. VI. Reduced Small Planet Occurrence in High Galactic Amplitude Stars
In this study, we performed a homogeneous analysis of the planets around FGK
dwarf stars observed by the Kepler and K2 missions, providing spectroscopic
parameters for 310 K2 targets -- including 239 Scaling K2 hosts -- observed
with Keck/HIRES. For orbital periods less than 40 days, we found that the
distribution of planets as a function of orbital period, stellar effective
temperature, and metallicity was consistent between K2 and Kepler, reflecting
consistent planet formation efficiency across numerous ~1 kpc sight-lines in
the local Milky Way. Additionally, we detected a 3X excess of sub-Saturns
relative to warm Jupiters beyond 10 days, suggesting a closer association
between sub-Saturn and sub-Neptune formation than between sub-Saturn and Jovian
formation. Performing a joint analysis of Kepler and K2 demographics, we
observed diminishing super-Earth, sub-Neptune, and sub-Saturn populations at
higher stellar effective temperatures, implying an inverse relationship between
formation and disk mass. In contrast, no apparent host-star spectral-type
dependence was identified for our population of Jupiters, which indicates
gas-giant formation saturates within the FGK mass regimes. We present support
for stellar metallicity trends reported by previous Kepler analyses. Using GAIA
DR3 proper motion and RV measurements, we discovered a galactic location trend:
stars that make large vertical excursions from the plane of the Milky Way host
fewer super-Earths and sub-Neptunes. While oscillation amplitude is associated
with metallicity, metallicity alone cannot explain the observed trend,
demonstrating that galactic influences are imprinted on the planet population.
Overall, our results provide new insights into the distribution of planets
around FGK dwarf stars and the factors that influence their formation and
evolution.Comment: 28 Pages, 12 Figures, 3 Tables; Accepted for Publication A
Overfitting Affects the Reliability of Radial Velocity Mass Estimates of the V1298 Tau Planets
Mass, radius, and age measurements of young (<100 Myr) planets have the power
to shape our understanding of planet formation. However, young stars tend to be
extremely variable in both photometry and radial velocity, which makes
constraining these properties challenging. The V1298 Tau system of four ~0.5
Rjup planets transiting a pre-main sequence star presents an important, if
stress-inducing, opportunity to directly observe and measure the properties of
infant planets. Su\'arez-Mascare\~no et al. (2021) published
radial-velocity-derived masses for two of the V1298 Tau planets using a
state-of-the-art Gaussian Process regression framework. The planetary densities
computed from these masses were surprisingly high, implying extremely rapid
contraction after formation in tension with most existing planet formation
theories. In an effort to further constrain the masses of the V1298 Tau
planets, we obtained 36 RVs using Keck/HIRES, and analyzed them in concert with
published RVs and photometry. Through performing a suite of cross validation
tests, we found evidence that the preferred model of SM21 suffers from
overfitting, defined as the inability to predict unseen data, rendering the
masses unreliable. We detail several potential causes of this overfitting, many
of which may be important for other RV analyses of other active stars, and
recommend that additional time and resources be allocated to understanding and
mitigating activity in active young stars such as V1298 Tau.Comment: 26 pages, 12 figures; published in A
Berufliche StabilitÀts- und FlexibilitÀtsorientierungen in Ostdeutschland: Ergebnisse eines Forschungspraktikums
Das im folgenden vorgestellte Projekt StabilitĂ€ts- und FlexibilitĂ€tsorientierungen in ostdeutschen LebensverlĂ€ufen wurde am Institut fĂŒr Soziologie der UniversitĂ€t Leipzig im Rahmen eines Lehrpraktikums durchgefĂŒhrt. In dem Projekt wurden berufliche StabilitĂ€ts- und FlexibilitĂ€tsorientierungen ostdeutscher BeschĂ€ftigter vor dem Hintergrund individueller Ressourcen und Gelegenheitsstrukturen untersucht. Anhand von 68 biographischen Interviews Ă€lterer und jĂŒngerer Kohorten sollte gezeigt werden, in welchem MaĂe individuelle Merkmale sowie familiĂ€re, arbeitsmarktliche, sozialpolitische und betriebliche Gelegenheitsstrukturen die individuellen Handlungsorientierungen beeinflussen. Vor dem Hintergrund der \"Entstandardisierung\" von Lebenslaufmustern und der \"Flexibilisierung\" von ErwerbsverlĂ€ufen wurde dabei nach den Ursachen und VerĂ€nderungen kohortenspezifischer Unterscheidungen berufsbiographischer EntwĂŒrfe gefragt.:Vorbemerkung; StabilitĂ€t und FlexibilitĂ€t im Lebensverlauf; Analytisches Modell und methodisches Vorgehen; Ergebnisse; BewĂ€ltigungsstrategien â Eine Zusammenfassung; Literatur, Anhan
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