133,117 research outputs found
Determinação do coeficiente de cultura (KC) e evapotranspiração da cultura do alho na região do planalto catarinense.
No full textProjeto acadêmico (graduação) - Universidade Federal de Santa Catarina. Campus Curitibanos. Ciências Rurais.O coeficiente de cultura (Kc) associado a evapotranspiração de referência (ETo) estima a evapotranspiração da cultura. Esses dados são de extrema importância para um bom manejo de irrigação melhorando aspectos, como o consumo de água e a produtividade do alho. O projeto tem por objetivo determinar o coeficiente de cultura para a utilização desses dados no controle de irrigação. O coeficiente de cultura será determinado através de uma relação da evapotranspiração da cultura (ETc) e da evapotranspiração de referência (ETo), estimadas pelos métodos de tanque lisímetro para a ETc e pela equação de Penman-Monteith e tanque classe A para a Eto. Espera-se construir a curva do coeficiente de cultura determinando a duração dos estágios de desenvolvimento da cultura e o valor do Kc para cada fases, melhorando assim o manejo de irrigação na produção do alho, diminuindo os impactos ambientais e melhorando a produtividade da cultura
Coeficiente de cultivo Kc
No full texteBook: Iniciación al Riego. Unidad 5 – Programación de riego
ISBN: 978-84-611-4187-3
Gráfico descriptivo de las cuatro fases de cultivo en función del valor de Kc.</p
HCO (N,Ka,Kc,J) distributions from near-threshold photolysis of H2CO (J,Ka,Kc)
No full textCopyright © 1998 American Institute of PhysicsThe dynamics of the reaction H2CO+hν(λ≈330 nm)→H+HCO have been studied following excitation of formaldehyde into the Ã(1A2) state, just above the dissociation threshold of the X̃(1A1) state. Formaldehyde was excited via specific J, Ka, Kc rotational states and the ensuing rotational distribution of HCO measured by fully resolving N, Ka, Kc, and J=N±S of the fragment. When only the N and Ka quantum numbers of both formaldehyde and the formyl radical are considered, the distributions are generally modeled well by phase space theory (PST). Within ≈10 cm−1 of the threshold, however, the PST predictions consistently exceed the experimental populations. This was accounted for by the inclusion of a centrifugal barrier in the PST model. The attractive part of the effective centrifugal potential was modeled by a dipole-induced dipole plus dispersion interaction. The barrier is weak and long range (&gt;5 Å). Resolution of Kc in the reaction, in both parent and product, gave large deviations from the PST model. The HCO population distributions separate according to whether Kc was the upper- or lower-energy state. Additionally, the upper/lower preference was sensitive to the choice of Kc in the parent. Insufficient data are currently available to quantify this observation. The product state distribution was also found to be independent of the spin–rotation state of HCO.Andrew C. Terentis, Siobhan E. Waugh, Gregory F. Metha, and Scott H. Kabl
KC-180‑2 Exerts Anti-SCLC Effects via Dual Inhibition of Tubulin Polymerization and Src Signaling
No full textIn this study, a series of N-benzyl-2-(5-phenylpyridin-2-yl)
acetamide-based derivatives were successfully designed and synthesized
as anti-cancer agents. KC-180-2 was screened as a potentially leading
compound with dual mechanisms of action: Src signaling and tubulin
polymerization inhibition. It efficiently suppressed the proliferation
of five cancer cell lines (MDA-MB-231, H446, SKOV-3, HepG2, and HT29),
with IC50 values ranging from 5 to 188 nM, especially small-cell
lung cancer (SCLC) cells (IC50, 5 nM). Correspondingly,
it exerted a significant therapeutic effect on the H446 small-cell
lung cancer xenograft model, significantly reducing the volume of
tumors without obvious toxicity. Mechanistically, this compound significantly
inhibited the polymerization of purified tubulin in vitro, inducing
G2/M cell cycle arrest and binding to the kinase catalytic domain
of the Src protein, which reduced the phosphorylation of Src. Thus,
KC-180-2 is a potential lead compound for the further development
of a new anti-tumor drug against SCLC
Comparison of Pt/zeolite catalysts for n-hexadecane hydroisomerization
No full textBifunctional platinum (0.5 wt.%) catalysts containing ZSM-5, ZSM-22, SAPO-11, Al-MCM-41, H-Y and H-P were tested for the hydroisomerization of n-hexadecane and their catalytic activities were compared. The Pt/ZSM-5, Pt/ZSM-22 and Pt/H-beta catalysts showed higher hydrocracking activity due to their strong acid sites,while the Pt/SAPO-11, Pt/Al-MCM-41 and Pt/H-Y catalysts with moderate acid strength showed better isomerization selectivity. Especially the Pt/Al-MCM-41 catalyst, where Al-MCM-41 was prepared by post-synthetic metal implantation method from siliceous MCM-41, showed the highest isomerization selectivity as well as the highest yield of multibranched isohexadecanes, presumably not only due to its moderately weak acidity and mesoscale pores but also due to higher metal dispersion. This result indicates that the Pt/Al-MCM-41 catalyst can be a promising candidate for good dewaxing catalysts. (C) 2000 Elsevier Science B.V. All rights reserved
Conservation of angular momentum in polyatomic photochemical reactions: H(2)CO(v,J,Ka,Kc)->H+HCO(N,Ka,Kc,J)
No full textLaser Techniques for State-Selected and State-to-State Chemistry IV / John W. Hepburn, Robert E. Continetti, Mark A. Johnson (eds.), pp. 36-46The photodissociation dynamics of the reaction H2CO + hv → H + HCO have been investigated just above the reaction threshold (λdiss ≈ 330 nm). Formaldehyde was excited into specific J, Ka, Kc rotational states of three vibrational levels in the à (1A2) state. Molecules in these states undergo internal conversion back to the X̃ (1A1) ground state on which the radical fragments are formed. The ensuing distribution of rotational energy in the HCO fragment was measured as a function of the N, Ka, Kc and J = N ± S quantum numbers of the fragment, and also the initial v, J, Ka, Kc quantum numbers of the parent. In a previous publication (J. Chem. Phys., in press) we investigated the dynamics of this reaction at low available energy and concluded that when only the N and Ka quantum numbers of both formaldehyde and the formyl radical are considered, the distributions are modelled well by phase space theory (PST). This is consistent with statistical dynamics on a bound, barrierless surface. Within ≈10 cm-1 of the energetic threshold, a centrifugal barrier affected the populations by inhibiting product states that require large orbital angular momentum. Resolution of Kc in the parent and product gave large deviations from the PST model, however little data were available to quantify this observation. In this work we have extended the number of initially excited H2CO levels to explore this "Kc effect" further. We find that in the HCO Ka = 1 manifold there is always a preference (up to 5:1) for HCO to be produced in either the higher energy Kc state (N1,N-1) or the lower energy state (N1,N). This preference is consistent over all N for any particular initial H2CO state but may vary for different initial states. Over the seven initial states probed here, four favoured Kc (lower) and the other three Kc (upper). A correlation between this Kc preference and the initial state was observed: odd Kc formaldehyde states produce Kc (lower) preference in HCO and vice versa for initially even Kc states. A comparison with one previous observation of this effect is presented, however no concrete explanation can be offered at this stage.Siobhan E. Waugh, Andrew C. Terentis, Gregory F. Metha and Scott H. Kabl
KC inhibition by anakinra-serum.
No full text<p>Increase in KC concentration in supernatants of MIN6 cells exposed to IL–1β compared to solvent alone in the presence of serum from participant 6 before (-60 min.) and after (40 min.) placebo or anakinra administration. Data represent the median and interquartile range, n = 3wells/condition. KC = keratinocyte-derived chemokine.</p
On minimal strongly KC-spaces
No full textsummary:In this article we introduce the notion of strongly -spaces, that is, those spaces in which countably compact subsets are closed. We find they have good properties. We prove that a space is maximal countably compact if and only if it is minimal strongly , and apply this result to study some properties of minimal strongly -spaces, some of which are not possessed by minimal -spaces. We also give a positive answer to a question proposed by O. T. Alas and R. G. Wilson, who asked whether every countably compact -space of cardinality less than has the -property. Using this we obtain a characterization of Katětov strongly -spaces and finally, we generalize one result of Alas and Wilson on Katětov- spaces
The Kc-effect
No full textThis thesis examines an experimental and theoretical investigation into the dynamics of the reaction
HZCO (v, J, K8, K) + hv -—> HCO (v, J, N, K3, K) + H (2H). Formaldehyde molecules were cooled in a
supersonic free-jet expansion, dissociated with a laser and the ensuing formyl (HCO) fragments were probed
by laser induced fluorescence spectroscopy.
The initial experiments were carried out near the energetic threshold where very little energy is
available to the product fragments. Subsequent experiments were carried out in three higher vibrational bands
in the A( IAz) state. At these energies the dissociative surface is the formaldehyde ground state So, and the
formyl and H fragments are formed in their ground electronic and vibrational states. Formaldehyde was
prepared in numerous rotational states, characterised by J = 0 to 5, K8 = 0 to 3 and Kc = 0 to 5. The ensuing
distribution of rotational energy in the HCO fragment was measured as a function of the N, K“, K and
J = N i S quantum numbers of the fragment, and also the initial v, J, K“, Kr quantum numbers of the parent.
The results found a dependence on both N and K2, in the fragment that could be modelled well using statistical
analysis (phase space theory). This is consistent with statistical dynamics on a bound, barrierless surface.
Within le cm‘1 of the energetic threshold, a centrifugal barrier affected the populations by inhibiting product
states that require large orbital angular momentum. No dependence on the spin states, S = il/z, has been
observed.
The results also show a strong dependence on the quantum number, Kc, of both the parent and the
product. When the Kc is resolved in both the parent and product, there are large deviations from the phase
space theory model. We find that in the HCO K,l = l manifold there is always a preference (up to 5:1) for
HCO to be produced in either the higher energy Kr state (NW—1) or the lower energy state (N1,N)- This
preference is consistent over all N for any particular initial HZCO state, but may vary for different initial states.
A correlation between this Kr preference and the initial state was observed: odd Kr formaldehyde states
produce preferentially KC (lower) of HC0 and vice versa for initially even Kr states.
A “Kr—effect” has been observed previously in the photodissociation of acetaldehyde and
propionaldehyde to produce HCO. These experiments saw a strong preference for the upper energy
component of the KC doublet, irrespective of the initial parent rotational state. The other system where Kc has
been seen to play a role is the photodissociation of water. When H20 is photodissociated from a variety of
rotational states with full KC resolution, different Kr states produced different A doublet states in the OH
fragment. The similarities with these previous studies and the “Kc—effect” in formaldehyde are discussed and
used as the starting point to develop a theory to explain the “Kr-effect” observations
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