The synthesis of potassium titanate by treatment of TiO2 with molten mixtures of KNO3 and KOH was investigated. The stage of TiO2 transformation into potassium titanate depends on the temperature of ...treatment, contents of KOH in the molten salt mixture and admixtures of K2CO3. The investigation of the chemical and phase composition as well as the size distribution of the powder produced allowed to consider the product obtained as a potassium polytitanate. The mechanism of the potassium polytitanate synthesis is analyzed. It is shown that the synthesized powder is a promising precursor to produce ceramics based on K2Ti6O13 and characterized with high mechanical properties.
La investigación tuvo como objetivo determinar si la aplicación del modelo holandés Van Hiele facilita el avance de los niveles de razonamiento geométrico de triángulos en los estudiantes del sexto ...ciclo de educación básica regular. El tipo de investigación fue aplicada, empleando como métodos específicos: el experimental, el estadístico y el hipotético deductivo; con un diseño preexperimental, con un solo grupo, conformado por 29 estudiantes de la IE “César Vallejo Mendoza” del centro poblado de Viñas, distrito de Acobambilla, provincia y región de Huancavelica a quienes se aplicó una prueba de entrada y otra de salida. El muestreo no probabilístico intencional, el procesamiento y análisis de los resultados se realizó aplicando la estadística, asimismo para la contrastación de las hipótesis se empleó la “t de student”. Como resultado obtuvimos que la aplicación del modelo de Van Hiele facilitó avanzar en el nivel de razonamiento geométrico (visualización, análisis y clasificación), debido a que la “t de student” calculada fue -16, 632 por lo que se rechazó la hipótesis nula, concluyéndose que sí existe una diferencia significativa en las medias de los grados de adquisición del nivel de razonamiento geométrico de triángulos antes y después de la aplicación del modelo Van Hiele.
Relevant information on the origins of the solar system and the early evolution of life itself can be derive from systematic and controlled exploration of water ice here on Earth. Therefore, over the ...last decades, a huge effort on experimental methodologies has been made to study the multiple crystal ice phases, which are observed outside our home-gravitational-potential. By employing (100)-oriented MgO lattice surface as a microcantilever sensor, we conducted the first ever study on the dynamics of the Structural Phase Transition at 185 K in water ice by means of coherent elastic scattering of electron diffraction. We estimate the amount of phonons caused by this transition applying precise quantum computing key tools, and resulting in a maximum value of 1.23 ± 0.02. Further applications of our microcantilever sensor were assessed using unambiguous mapping of the surface stress induced by the c(Formula: see text) → p(Formula: see text) Structural Phase Transition of the interstellar ice formulated on the Williamsom-Hall model. This development paves the way and thus establishes an efficient characterization tool of the surface mechanical strains of materials with potential applications arising from interstellar ice inclusive glaciers to the wide spectrum of solid-state physics.
Introduction: We investigated the meaning of sixteen achievement emotion words--anger, anxiety, boredom, contentment, despair, disappointment, frustration, guilt, hope, hopelessness, joy, pride, ...relief, sadness, shame, and surprise--, specifically in terms of their action tendencies component, through a modified version of the CoreGRID questionnaire. Our aim was to identify in which cases the achievement context modifies the semantic profiles of each emotion word, specifically in terms of their action tendencies component, as compared to an unspecified general context. Method: Forty-one participants (22 females; Msubscript age = 21.8, SD = 3.5), and another group of thirty-six participants (21 females; Msubscript age = 20.42, SD = 2.8), rated the likelihood of eighteen action tendencies to be part of the meaning of each emotion word in an achievement context condition and in a general context condition, respectively. Results: In both conditions, Cronbach's Alpha ranged from 0.95 to 0.98. Data analysis revealed statistically significant differences for every emotion investigated, suggesting an influence of context in their semantic profile. Discussion: The discussion of these results is centered mainly around data from other studies that were interested in the motivational component of emotions, since there is a lacking of research on semantic profiles of achievement emotions. Finally, we make suggestions on directions for future research and inform of the limitations of our study.
Borexino has been running since May 2007 at the Laboratori Nazionali del Gran Sasso laboratory in Italy with the primary goal of detecting solar neutrinos. The detector, a large, unsegmented liquid ...scintillator calorimeter characterized by unprecedented low levels of intrinsic radioactivity, is optimized for the study of the lower energy part of the spectrum. During Phase-I (2007-2010), Borexino first detected and then precisely measured the flux of the super(7)Be solar neutrinos, ruled out any significant day-night asymmetry of their interaction rate, made the first direct observation of the pep neutrinos, and set the tightest upper limit on the flux of solar neutrinos produced in the CNO cycle (carbon, nitrogen, oxigen) where carbon, nitrogen, and oxygen serve as catalysts in the fusion process. In this paper we discuss the signal signature and provide a comprehensive description of the backgrounds, quantify their event rates, describe the methods for their identification, selection, or subtraction, and describe data analysis. Key features are an extensive in situ calibration program using radioactive sources, the detailed modeling of the detector response, the ability to define an innermost fiducial volume with extremely low background via software cuts, and the excellent pulse-shape discrimination capability of the scintillator that allows particle identification. We report a measurement of the annual modulation of the super(7)Be neutrino interaction rate. The period, the amplitude, and the phase of the observed modulation are consistent with the solar origin of these events, and the absence of their annual modulation is rejected with higher than 99% C.L. The physics implications of Phase-I results in the context of the neutrino oscillation physics and solar models are presented.
A review of current literature on mammalian hosts' sexual dimorphism (SD) in parasitic infections revealed that (1) it is a scarcely and superficially studied biological phenomenon of considerable ...significance for individual health, behavior, and lifestyles and for the evolution of species; (2) there are many notable exceptions to the rule of a favorable female bias in susceptibility to infection; (3) a complex network of molecular and cellular reactions connecting the host's immuno-neuro-endocrine systems with those of the parasite is responsible for the host–parasite relationship rather than just an adaptive immune response and sex hormones; (4) a lack of gender-specific immune profiles in response to different infections; (5) the direct effects of the host hormones on parasite physiology may significantly contribute to SD in parasitism; and (6) the need to enrich the reductionist approach to complex biological issues, like SD, with more penetrating approaches to the study of cause–effect relationships, i.e., network theory. The review concludes by advising against generalization regarding SD and parasitism and by pointing to some of the most promising lines of research.
Powders of K
0.5
Na
0.5
NbO
3
lead-free piezoelectric ceramics were successfully synthesized via conventional and microwave-assisted heating. A single-mode microwave equipment was used to perform the ...synthesis following the mixed oxide route and then sintering at different temperatures. The synthesized powders obtained and then sintered by microwave and conventional methods were evaluated by thermogravimetry analysis, X-ray diffraction, field emission scanning electron microscopy and electrical properties. Microwave synthesis processing for 10 min at 650 °C using a heating rate of 30 °C/min promotes the formation of K
0.5
Na
0.5
NbO
3
particles in the range of 100–300 nm. Perovskite structure formed during calcination shows the coexistence of tetragonal-orthorhombic geometry according to X-ray diffraction patterns. The microwave-obtained particles are consistent with the theoretical stoichiometry. Particle size increases up to 1 µm as the reaction temperature is increased from 650 to 800 °C. An intermediate phase (K,Na)
2
Nb
4
O
11
is formed in the entire range of synthesis temperatures studied. The samples obtained by microwave sintering show a structure similar to the samples sintered by the conventional method. However, the porosity observed (~ 8–6%) in the microstructure of the microwave-sintered piezoelectric materials affects the density of the material, and these defects cause a decrease in the dielectric values. The highest d
33
value of 126 pC/N was obtained for samples obtained by conventional at 1100 °C-2 h compared to the microwave samples (~ 25 pC/N).
This study investigated causes of persistent fecal indicator bacteria (FIB) in beach sand under the pier in Santa Monica, CA. FIB levels were up to 1000 times higher in sand underneath the pier than ...that collected from adjacent to the pier, with the highest concentrations under the pier in spring and fall.
Escherichia coli
(EC) and enterococci (ENT) under the pier were significantly positively correlated with moisture (
ρ
= 0.61,
p
< 0.001,
n
= 59;
ρ
= 0.43,
p
< 0.001,
n
= 59, respectively), and ENT levels measured by qPCR (qENT) were much higher than those measured by membrane filtration (cENT). Microcosm experiments tested the ability of EC, qENT, cENT, and general
Bacteroidales
(GenBac) to persist under in situ moisture conditions (10 and 0.1%). Decay rates of qENT, cENT, and GenBac were not significantly different from zero at either moisture level, while decay rates for EC were relatively rapid during the microcosm at 10% moisture (
k
= 0.7 days
−1
). Gull/pelican marker was detected at 8 of 12 sites and no human-associated markers (TaqHF183 and HumM2) were detected at any site during a 1-day site survey. Results from this study indicate that the high levels of FIB observed likely stem from environmental sources combined with high persistence of FIB under the pier.
Thioureas are an important scaffold in organocatalysis because of their ability to form hydrogen bonds that activate substrates and fix them in a defined position, which allows a given reaction to ...occur. Structures that enhance the acidity of the thiourea are usually used to increase the hydrogen-bonding properties, such as 3,5-bis(trifluoromethyl)phenyl and boronate ureas. Herein, we report the synthesis of bifunctional thioureas with a chiral moiety that include either a trifluoromethyl or methyl group. Their catalytic performance in representative Michael addition reactions was used in an effort to compare the electronic effects of the fluorination at the methyl group. The observed differences concerning yields and ee values cannot be attributed solely to the different steric environments; theoretical results indicate distinct interactions within the corresponding transition states. The calculated transition states show that the fluorinated catalysts have stronger N–H···O and C–H···F hydrogen bonds, while the nonfluorinated systems have C–H···π contacts. These results have shown that a variety of hydrogen-bonding interactions are important in determining the yield and selectivity of thiourea organocatalysis. These details can be further exploited in catalyst design.
Background: The Syrian Arab Republic (SAR) is experiencing high rates of malnutrition. While many adults experience overweight and obesity, as a direct result of the continuing conflict, SAR is also ...noted as one of the most food-insecure regions in the Arab world. To combat the health impacts and outcomes related to diet and dietary behaviors, trained nutrition professionals are needed. We aimed to examine current nutrition-affiliated programs offered in post-secondary institutions in the SAR.
Methods: The search was conducted between Jan and Feb 2021. An electronic review of universities and colleges’ websites, department webpages, and academic programs’ homepages and resources of all the private and public universities in SAR was conducted to find programs related to nutrition, nutrition sciences, and dietetics.
Results: Only 13%, or 4 out of 30 SAR colleges and universities had bachelor’s programs in nutrition or nutrition science, and none had nutrition programs at the graduate or terminal degree levels.
Conclusion: A pathway for integration of graduates from nutrition sciences into the healthcare and public health workforce should be defined and an understanding of the value of those with a degree in nutrition should be cultivated in clinical and community care settings. Partnering with existing or creating independent organizations charged with defining the scope of practice and ensuring educational quality and competence of graduating students, as well as readiness to practice as part of a healthcare team or in a public health nutrition role will be integral to moving the nutrition profession forward in the SAR.
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