The Synthesis and Characterization of Some Fluoride Perovskites, an Undergraduate Experiment in Solid State Chemistry

In light of the increasing importance of solid state chemistry, an experiment dealing with at least some aspects of this rapidly expanding area should he included in advanced chemistry laboratories. Herein is described one of the experiments that we have developed to meet this need. This experiment was designed for a senior level integrated chemistry lab taken by all our chemistry majors. Normally six to eight hours are needed to complete this experiment. This experiment deals with the synthesis and characterization of a perovskite. Perovskites were chosen because compounds with this structure are important in solid state technology, and since most of them are cubic, the characterization by X-ray diffraction is simplified. In addition, magnetic ordering may he observed, and the effects of a Jahn-Teller distortion seen

Integration of ancient DNA with transdisciplinary dataset finds strong support for Inca resettlement in the south Peruvian coast

Ancient DNA (aDNA) analysis provides a powerful means of investigating human migration, social organization, and a plethora of other crucial questions about humanity’s past. Recently, specialists have suggested that the ideal research design involving aDNA would include multiple independent lines of evidence. In this paper, we adopt a transdisciplinary approach integrating aDNA with archaeological, biogeochemical, and historical data to investigate six individuals found in two cemeteries that date to the Late Horizon (1400 to 1532 CE) and Colonial (1532 to 1825 CE) periods in the Chincha Valley of southern Peru. Genomic analyses indicate that these individuals are genetically most similar to ancient and present-day populations from the north Peruvian coast located several hundred kilometers away. These genomic data are consistent with 16th century written records as well as ceramic, textile, and isotopic data. These results provide some of the strongest evidence yet of state-sponsored resettlement in the pre-Colonial Andes. This study highlights the power of transdisciplinary research designs when using aDNA data and sets a methodological standard for investigating ancient mobility in complex societies

IL-33 Is Produced by Mast Cells and Regulates IgE-Dependent Inflammation

Background: IL-33 is a recently characterized IL-1 family cytokine and found to be expressed in inflammatory diseases, including severe asthma and inflammatory bowl disease. Recombinant IL-33 has been shown to enhance Th2-associated immune responses and potently increase mast cell proliferation and cytokine production. While IL-33 is constitutively expressed in endothelial and epithelial cells, where it may function as a transcriptional regulator, cellular sources of IL-33 and its role in inflammation remain unclear. Methodology/Principal Findings: Here, we identify mast cells as IL-33 producing cells. IgE/antigen activation of bone marrow-derived mast cells or a murine mast cell line (MC/9) significantly enhanced IL-33. Conversely, recombinant IL-33 directly activated mast cells to produce several cytokines including IL-4, IL-5 and IL-6 but not IL-33. We show that expression of IL-33 in response to IgE-activation required calcium and that ionomycin was sufficient to induce IL-33. In vivo, peritoneal mast cells expressed IL-33 and IL-33 levels were significantly lower within the skin of mast cell deficient mice, compared to littermate controls. Local activation of mast cells promotes edema, followed by the recruitment of inflammatory cells. We demonstrate using passive cutaneous anaphylaxis, a mast cell-dependent model, that deficiency in ST2 or antibody blockage of ST2 or IL-33 ablated the late phase inflammatory response but that the immediate phase response was unaffected. IL-33 levels in the skin were significantly elevated only during the late phase

Synaptic Transmission from Horizontal Cells to Cones Is Impaired by Loss of Connexin Hemichannels

In the vertebrate retina, horizontal cells generate the inhibitory surround of bipolar cells, an essential step in contrast enhancement. For the last decades, the mechanism involved in this inhibitory synaptic pathway has been a major controversy in retinal research. One hypothesis suggests that connexin hemichannels mediate this negative feedback signal; another suggests that feedback is mediated by protons. Mutant zebrafish were generated that lack connexin 55.5 hemichannels in horizontal cells. Whole cell voltage clamp recordings were made from isolated horizontal cells and cones in flat mount retinas. Light-induced feedback from horizontal cells to cones was reduced in mutants. A reduction of feedback was also found when horizontal cells were pharmacologically hyperpolarized but was absent when they were pharmacologically depolarized. Hemichannel currents in isolated horizontal cells showed a similar behavior. The hyperpolarization-induced hemichannel current was strongly reduced in the mutants while the depolarization-induced hemichannel current was not. Intracellular recordings were made from horizontal cells. Consistent with impaired feedback in the mutant, spectral opponent responses in horizontal cells were diminished in these animals. A behavioral assay revealed a lower contrast-sensitivity, illustrating the role of the horizontal cell to cone feedback pathway in contrast enhancement. Model simulations showed that the observed modifications of feedback can be accounted for by an ephaptic mechanism. A model for feedback, in which the number of connexin hemichannels is reduced to about 40%, fully predicts the specific asymmetric modification of feedback. To our knowledge, this is the first successful genetic interference in the feedback pathway from horizontal cells to cones. It provides direct evidence for an unconventional role of connexin hemichannels in the inhibitory synapse between horizontal cells and cones. This is an important step in resolving a long-standing debate about the unusual form of (ephaptic) synaptic transmission between horizontal cells and cones in the vertebrate retina

Peri-Pubertal Emergence of UNC-5 Homologue Expression by Dopamine Neurons in Rodents

Puberty is a critical period in mesocorticolimbic dopamine (DA) system development, particularly for the medial prefrontal cortex (mPFC) projection which achieves maturity in early adulthood. The guidance cue netrin-1 organizes neuronal networks by attracting or repelling cellular processes through DCC (deleted in colorectal cancer) and UNC-5 homologue (UNC5H) receptors, respectively. We have shown that variations in netrin-1 receptor levels lead to selective reorganization of mPFC DA circuitry, and changes in DA-related behaviors, in transgenic mice and in rats. Significantly, these effects are only observed after puberty, suggesting that netrin-1 mediated effects on DA systems vary across development. Here we report on the normal expression of DCC and UNC5H in the ventral tegmental area (VTA) by DA neurons from embryonic life to adulthood, in both mice and rats. We show a dramatic and enduring pubertal change in the ratio of DCC:UNC5H receptors, reflecting a shift toward predominant UNC5H function. This shift in DCC:UNC5H ratio coincides with the pubertal emergence of UNC5H expression by VTA DA neurons. Although the distribution of DCC and UNC5H by VTA DA neurons changes during puberty, the pattern of netrin-1 immunoreactivity in these cells does not. Together, our findings suggest that DCC:UNC5H ratios in DA neurons at critical periods may have important consequences for the organization and function of mesocorticolimbic DA systems

Non-invasive bladder function measures in healthy, asymptomatic female children and adolescents: A systematic review and meta-analysis

BackgroundLower urinary tract symptoms (LUTS) are common in children and adolescents. Non-invasive tests evaluating bladder function are generally preferred over invasive tests, yet few studies have explored the range of normative values for these tests in healthy, asymptomatic children.ObjectiveTo define normative reference ranges for non-invasive tests of bladder function in healthy, asymptomatic girls and adolescents.Study designA comprehensive search strategy was performed in seven electronic databases through October 2019. English-language studies reporting data on voiding frequency, voided and postvoid residual volumes (PVR) and uroflowmetry results in healthy, asymptomatic girls (mean age ≥ 5 years) were included. Two independent reviewers performed study review, data extraction, and quality assessment. Overall mean estimates and 95% confidence intervals for each bladder function parameter were calculated using random effects models, and 95% normative reference values were estimated.ResultsTen studies met eligibility criteria for the meta-analysis (n = 2143 girls, age range: 3-18). Mean estimates of maximum voided volume and PVR were 233.4 ml (95% CI 204.3-262.6; n = 1 study) and 8.6 ml (95% CI 4.8-12.4; n = 2 studies) respectively. Pooled mean estimates for uroflowmetry parameters were: 21.5 ml/s (95% CI 20.5-2.5) for maximum flow rate (n = 6 studies), 12.5 ml/s (95% CI 11.2-13.8) for mean flow rate (n = 6 studies), 6.8 s (95% CI 4.4-9.3) for time to maximum flow (n = 3 studies), 15.7 s (95% CI 13.0-18.5) for flow time (n = 3 studies), and 198.7 ml (95% CI 154.2-234.2) for voided volume (n = 9 studies). No studies reported estimates of voiding frequency. Between-study heterogeneity was high (89.0-99.6%).ConclusionsAlthough we were able to calculate pooled mean estimates for several parameters, the small number of included studies and the wide age ranges of participants preclude generalization of reference values to all healthy girls. Further research is needed to determine normative reference values within specific age groups