164 research outputs found
The Reaction of Allyl Isothiocyanate with Hydroxyl/Water and β-Cyclodextrin Using Ultraviolet Spectrometry
Metodom ultraljubičaste spektrofotometrije istražena je reakcija alil izotiocijanata (AITC) s hidroksilom/vodom i β-ciklodekstrinom (β-CD) u mediju različite kiselosti odnosno lužnatosti. Mjereni su kinetički parametri reakcije. Utvrđeno je da se, nakon što AITC prijeđe u tioureu, apsorpcijski pik pomakne s 240 na 226 nm i da molarna apsorpcija poraste 16 puta. Reakcija se može okarakterizirati kao pseudoreakcija prvog reda jer je konstantna koncentracija hidroksila. β-CD može inhibirati reakciju AITC s hidroksilom/vodom, tj. hidrolizu AITC. Izračunati su konstanta nastajanja (Ka) i termodinamički parametri kompleksne reakcije. S povećanjem temperature smanjuje se Ka. Rezultati pokusa pokazuju da proces uključuje egzotermnu reakciju koju pokreće entalpija praćena negativnom entropijom.The reaction of allyl isothiocyanate (AITC) with hydroxyl/water and β-cyclodextrin (β-CD) in different acidic-alkaline media has been investigated by ultraviolet spectrometry. The kinetic parameters of the reaction were measured. It was found that after AITC translating into thiourea, the absorption peak shifted from 240 to 226 nm and the molar absorptivity increased about 16 times. The reaction can be seen as a pseudo first order reaction because the concentration of hydroxyl was constant. β-CD can inhibit the reaction of AITC with hydroxyl/water, i.e. the hydrolysis of AITC. The formation constant (Ka) and thermodynamic parameters of the complex reaction were calculated. Ka decreased with the increase of temperature. The experimental results indicated that the inclusive process was an exothermic and enthalpy-driven process accompanied with a negative entropic contribution
The mitochondrial alternative oxidase pathway protects the photosynthetic apparatus against photodamage in Rumex K-1 leaves
<p>Abstract</p> <p>Background</p> <p>It is known that excess reducing equivalents in the form of NADPH in chloroplasts can be transported via shuttle machineries, such as the malate-oxaloacetate (OAA) shuttle, into the mitochondria, where they are efficiently oxidised by the mitochondrial alternative oxidase (AOX) respiratory pathway. Therefore, it has been speculated that the AOX pathway may protect plants from photoinhibition, but the mechanism by which this protection occurs remains to be elucidated.</p> <p>Results</p> <p>The observation that the malate-OAA shuttle activity and the AOX pathway capacity increased markedly after intense light treatment in <it>Rumex </it>K-1 leaves indicates that excess NADPH was transported from the chloroplasts and oxidised by the AOX pathway. The inhibition of the AOX pathway by salicylhydroxamic acid (SHAM) caused the over-reduction of the photosystem I (PSI) acceptor side, as indicated by the increases in the extent of reduction of P700<sup>+</sup>. Furthermore, the photosynthetic linear electron flow was restricted, which was indicated by the decreases in the PSII electron transport rate (ETR) and the photosynthetic O<sub>2 </sub>evolution rate. The restriction of the photosynthetic linear electron flow, which generates the thylakoid ΔpH, inevitably decreased the de-epoxidation of the xanthophyll cycle (ΔPRI). Therefore, the induction of non-photochemical quenching (NPQ) was suppressed when the AOX pathway was inhibited. The effect of the inhibition of the AOX pathway on NPQ induction was less at 20 mM NaHCO<sub>3 </sub>than at 1 mM NaHCO<sub>3</sub>. The suppression of NPQ induction by the inhibition of the AOX pathway was also observed during the induction phase of photosynthesis. In addition, the inhibition of the AOX pathway increased the accumulation of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), suggesting that the AOX pathway functions as an antioxidant mechanism.</p> <p>Conclusions</p> <p>The inhibition of the AOX pathway resulted in the rapid accumulation of NADPH in the chloroplasts, which caused the over-reduction of the PSI acceptor side. Furthermore, the restriction of the photosynthetic linear electron flow due to the inhibition of the AOX pathway limited the generation of the thylakoid ΔpH and suppressed the induction of NPQ. Therefore, the mitochondrial AOX pathway protected the photosynthetic apparatus against photodamage by alleviating the over-reduction of the PSI acceptor side and accelerating the induction of NPQ in <it>Rumex </it>K-1 leaves.</p
Hilbert-Huang Transform analysis of quasi-periodic oscillations in MAXI J1820+070
We present time-frequency analysis, based on the Hilbert-Huang transform
(HHT), of the evolution on the low-frequency quasi-periodic oscillations
(LFQPOs) observed in the black hole X-ray binary MAXI J1820+070. Through the
empirical mode decomposition (EMD) method, we decompose the light curve of the
QPO component and measure its intrinsic phase lag between photons from
different energy bands. We find that the QPO phase lag is negative (low energy
photons lag behind high energy photons), meanwhile the absolute value of the
lag increases with energy. By applying the Hilbert transform to the light curve
of the QPO, we further extract the instantaneous frequency and amplitude of the
QPO. Compared these results with those from the Fourier analysis, we find that
the broadening of the QPO peak is mainly caused by the frequency modulation.
Through further analysis, we find that these modulations could share a common
physical origin with the broad-band noise, and can be well explained by the
internal shock model of the jet
A simulation study on the measurement of D0-D0bar mixing parameter y at BES-III
We established a method on measuring the \dzdzb mixing parameter for
BESIII experiment at the BEPCII collider. In this method, the doubly
tagged events, with one decays to
CP-eigenstates and the other decays semileptonically, are used to
reconstruct the signals. Since this analysis requires good separation,
a likelihood approach, which combines the , time of flight and the
electromagnetic shower detectors information, is used for particle
identification. We estimate the sensitivity of the measurement of to be
0.007 based on a fully simulated MC sample.Comment: 6 pages, 7 figure
EVALUATION OF EFFECTIVENESS IN A NOVEL WOUND HEALING OINTMENT-CROCODILE OIL BURN OINTMENT
Background: Crocodile oil and its products are used as ointments for burns and scalds in traditional medicines. A new
ointment formulation - crocodile oil burn ointment (COBO) was developed to provide more efficient wound healing
activity. The purpose of the study was to evaluate the burn healing efficacy of this new formulation by employing deep
second-degree burns in a Wistar rat model. The analgesic and anti-inflammatory activities of COBO were also studied
to provide some evidences for its further use.
Materials and methods: The wound healing potential of this formulation was evaluated by employing a deep
second-degree burn rat model and the efficiency was comparatively assessed against a reference ointment – (1% wt ⁄ wt)
silver sulfadiazine (SSD). After 28 days, the animals were euthanized and the wounds were removed for transversal
and longitudinal histological studies. Acetic acid-induced writhing in mice was used to evaluate the analgesic activity
and its anti-inflammatory activity was observed in xylene -induced edema in mice.
Results: COBO enhanced the burn wound healing (20.5±1.3 d) as indicated by significant decrease in wound closure
time compared with the burn control (25.0±2.16 d) (
The accretion flow geometry of MAXI J1820+070 through broadband noise research with Insight-HXMT
Here we present a detailed study of the broadband noise in the power density
spectra of the black hole X-ray binary MAXI J1820+070 during the hard state of
its 2018 outburst, using the Hard X-ray Modulation Telescope (Insight-HXMT)
observations. The broadband noise shows two main humps, which might separately
correspond to variability from a variable disk and two Comptonization regions.
We fitted the two humps with multiple Lorentzian functions and studied the
energy-dependent properties of each component up to 100--150 keV and their
evolution with spectral changes. The lowest frequency component is considered
as the sub-harmonic of QPO component and shows different energy dependence
compared with other broadband noise components. We found that although the
fractional rms of all the broadband noise components mainly decrease with
energy, their rms spectra are different in shape. Above 20--30 keV, the
characteristic frequencies of these components increase sharply with energy,
meaning that the high-energy component is more variable on short timescales.
Our results suggest that the hot inner flow in MAXI J1820+070 is likely to be
inhomogeneous. We propose a geometry with a truncated accretion disk, two
Comptonization regions
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