10 research outputs found
Analytical study of modified Manashiladi Lepa into Ointment
Lepa Kalpana is one amongst the external application used in Ayurveda. Manashiladi Lepa is a formulation explained in âRasa Tantra Sara Va Siddha Prayoga Sangrahaâ for the prevention of scar in the skin surface. The formulation contains Ghrita and Madhu which is to be mixed with the powder of the herbs told in the formulation. In the present scenario, the Lepa Kalpana is not liked by the patients themselves as it leaves behind residual marks on the skin surface and stains the cloth if it comes in contact with it. Hence a modified Lepa in the form of ointment which contains reduced amount of oiliness and good packing is accepted by all. Literary review done through various sources like books, journals and internet revealed that, no modification studies have been carried out on this formulation yet. The Lepa is modified into an ointment for its easy acceptability and usage. The formulation is tested for its analytical values and discussed in the article
Evaluation of polyherbal formulation and synthetic choline chloride on choline deficiency model in broilers: implications on zootechnical parameters, serum biochemistry and liver histopathology
Objective The study was designed to establish choline deficiency model (CDM) in broilers for evaluating efficacy of polyherbal formulation (PHF) in comparison with synthetic choline chloride (SCC). Methods A total of 2,550 one-day-old Cobb 430 broiler chicks were randomly assigned to different groups in three experiments. In experiment 1, G1 and G2 served as normal controls and were fed a basal diet with 100% soybean meal (SBM) as a major protein source supplemented with and without SCC, respectively. In G3, G4, G5, and G6 groups, SBM was replaced at 25%, 50%, 75%, and 100% by soy protein isolate (SPI) to induce a graded level of choline deficiency. In experiment 2, PHF (500 and 1,000 g/ton) in comparison with SCC (1,000 g/ton) were evaluated. In experiment 3, dose-response of PHF (200, 400, and 500 g/ton) with SCC (400 g/ton) was determined. Results Replacement of SBM by SPI produced a linear decrease in body weight gain (BWG) with a poor feed conversion ratio (FCR). 25% SBM replacement by SPI yielded an optimum negative impact on BWG and FCR; hence, it is considered for further studies. In experiment 2, PHF (500 and 1,000 g/ton) and SCC (1,000 g/ton) showed a similar performance in BWG, FCR and relative liver weight. In experiment 3, PHF produced an optimum efficacy at 400 g/ton and was comparable to SCC in the restoration of serum aspartate aminotransferase activity, abdominal fat, breast muscle lipid content and liver histopathological abnormalities. Conclusion Replacement of SBM by SPI caused choline deficiency characterised by worsening of BWG, FCR, elevation in liver enzymes and histopathological changes indicating fatty liver. CDM was found valid for evaluating SCC and PHF. It is concluded that PHF has the potential to mimic biological activities of SCC through the restoration of negative effects caused by CDM
Perceptron learning rule derived from spike-frequency adaptation and spike-time-dependent plasticity
It is widely believed that sensory and motor processing in the brain is based on simple computational primitives rooted in cellular and synaptic physiology. However, many gaps remain in our understanding of the connections between neural computations and biophysical properties of neurons. Here, we show that synaptic spike-time-dependent plasticity (STDP) combined with spike-frequency adaptation (SFA) in a single neuron together approximate the well-known perceptron learning rule. Our calculations and integrate-and-fire simulations reveal that delayed inputs to a neuron endowed with STDP and SFA precisely instruct neural responses to earlier arriving inputs. We demonstrate this mechanism on a developmental example of auditory map formation guided by visual inputs, as observed in the external nucleus of the inferior colliculus (ICX) of barn owls. The interplay of SFA and STDP in model ICX neurons precisely transfers the tuning curve from the visual modality onto the auditory modality, demonstrating a useful computation for multimodal and sensory-guided processing
Phosphorus(V) Porphyrin-Manganese(II) Terpyridine Conjugates: Synthesis, Spectroscopy, and Photo-Oxidation Studies on a SnO<sub>2</sub> Surface
A major challenge
in designing artificial photosynthetic systems is to find a suitable
mimic of the highly oxidizing photoactive species P<sub>680</sub> in
photosystem II. High-potential phosphorusÂ(V) porphyrins have many
attractive properties for such a mimic but have not been widely studied.
Here, we report the synthesis and photophysical characterization of
a novel phosphorusÂ(V) octaethylporphyrinâoxyphenylâterpyridine
conjugate (PPor-OPh-tpy, <b>1</b>) and its corresponding manganeseÂ(II)
complex (PPor-OPh-MnÂ(tpy)ÂCl<sub>2</sub>, <b>2</b>). The X-ray
structure of <b>2</b> shows that the MnÂ(II) and PÂ(V) centers
are 11.783 Ă
apart and that the phenoxy linker is not fully conjugated
with the terpyridine ligand. The porphyrin fluorescence in <b>1</b> and <b>2</b> is strongly quenched and has a shorter lifetime
compared to a reference compound without the terpyridine ligand. This
suggests that electron transfer from tpy or MnÂ(tpy) to the excited
singlet state of the PPor may be occurring. However, femtosecond transient
absorbance data show that the rate of relaxation to the ground state
in <b>1</b> and <b>2</b> is comparable to the fluorescence
lifetimes. Thus, if charge separation is occurring, its lifetime is
short. Because both <b>1</b> and <b>2</b> are positively
charged, they can be electrostatically deposited onto the surface
of negatively charged SnO<sub>2</sub> nanoparticles. Freeze-trapping
EPR studies of <b>2</b> electrostatically bound to SnO<sub>2</sub> suggest that excitation of the porphyrin results in electron injection
from <sup>1</sup>PPor* into the conduction band of SnO<sub>2</sub> and that the resulting PPor<sup>â˘+</sup> species acquires
enough potential to photo-oxidize the axially bound MnÂ(II) (tpy) moiety
to MnÂ(III) (tpy)
Mutagenicity and Acute Oral Toxicity Test for Herbal Poultry Feed Supplements
Herbal products are being used and trusted globally for thousands of years for their health benefits and limited side effects. Globally, a general belief amongst the consumers is that herbal supplements are always safe because they are ânatural.â But later, research reveals that they may not be safe. This raises concern on their safety and implications for their use as feed supplement or medicine. Toxicity testing can reveal some of the risks that may be associated with use of herbs, therefore avoiding potential harmful effects. The present study was designed to investigate five poultry feed supplements (PFS), EGMAXÂŽ (to revitalize ovarian activity), FEED-X⢠(feed efficiency enhancer), KOLIN PLUS⢠(natural replacer of synthetic choline chloride), PHYTOCEEÂŽ (natural defence enhancer), and STODIÂŽ (to prevent and control loose droppings), for their possible mutagenicity and toxicity. Bacterial reverse mutation (BRMT) and acute oral toxicity tests were employed to assess the PFS for their possible mutagenicity and toxicity. Results indicated that the PFS were devoid of mutagenic effects in BRMT and showed higher safety profile in rodent acute oral toxicity test
Fluorinated Antimony(V) Tetraarylporphyrins as High-Valent Electron Acceptors with Unparalleled Reduction Potentials
A series of fluorinated antimony(V) porphyrins, SbTPP(OMe)2¡PF6, SbTPP(OTFE)2¡PF6, SbT(4F)PP(OMe)2¡PF6, SbT(35F)PP(OMe)2¡PF6, SbT(345F)PP(OMe)2¡PF6, SbT(4CF3)PP(OMe)2¡PF6, SbT(35CF3)PP(OMe)2¡PF6, and
SbT(35CF3)PP(OTFE)2¡PF6, have
been synthesized with phenyl [P], 4-fluorophenyl [(4F)P], 3,5-difluorophenyl
[(35F)P], 3,4,5-difluorophenyl [(345F)P], 4-trifluoromethylphenyl
[(4CF3)P], and 3,5-bis(trifluoromethyl)phenyl [(35CF3)P], in the meso-positions. Additionally, the SbTPP(OTFE)2¡PF6 and SbT(35CF3)PP(OTFE)2¡PF6 carry trifluoroethoxy units in their
axial-positions. The fluorination on the porphyrin peripherals ranges
from zero fluorine atoms in SbTPP(OMe)2¡PF6 to 30 fluorine atoms in SbT(35CF3)PP(OTFE)2¡PF6. X-ray crystallography confirmed the structures
of the investigated antimony(V) porphyrins. The absorption spectra
depend on the number of fluorine atoms as it is blue-shifted with
increasing fluorination. The series also exhibited rich redox chemistry
with two reduction processes and one oxidation process. Remarkably,
these porphyrins manifested the lowest reduction potentials reported
among the main-group porphyrins, which are as low as â0.08
V vs SCE for SbT(35CF3)PP(OTFE)2¡PF6. On the contrary, the oxidation potentials were found to
be very large, that is equal to 2.20 V vs SCE or even higher for SbT(4CF3)PP(OMe)2¡PF6 or SbT(35CF3)PP(OMe)2¡PF6 and SbT(35CF3)PP(OTFE)2¡PF6, respectively. These unprecedented
potentials are due to a combination of two factors: (i) the +5-oxidation
state of antimony in the porphyrin cavity and (ii) the presence of
the strong electron-withdrawing fluorine atoms on the porphyrin peripherals.
Density functional theory (DFT) calculations were used to support
the experimental results. The systematic study of antimony(V) porphyrins,
especially their high potentials, make them ideal for the construction
of photoelectrodes and excellent electron acceptors for photoelectrochemical
cells and artificial photosynthetic systems, respectively, for solar
energy conversion and storage applications
Modulation of Energy Transfer into Sequential Electron Transfer upon Axial Coordination of Tetrathiafulvalene in an Aluminum(III) PorphyrinâFree-Base Porphyrin Dyad
Axially assembled
aluminumÂ(III) porphyrin based dyads and triads have been constructed
to investigate the factors that govern the energy and electron transfer
processes in a perpendicular direction to the porphyrin plane. In
the aluminumÂ(III) porphyrinâfree-base porphyrin (AlPor-Ph-H<sub>2</sub>Por) dyad, the AlPor occupies the basal plane, while the free-base
porphyrin (H<sub>2</sub>Por) with electron withdrawing groups resides
in the axial position through a benzoate spacer. The NMR, UVâvisible
absorption, and steady-state fluorescence studies confirm that the
coordination of pyridine appended tetrathiafulvalene (TTF) derivative
(TTF-py or TTF-Ph-py) to the dyad in noncoordinating solvents afford
vertically arranged supramolecular self-assembled triads (TTF-pyâAlPor-Ph-H<sub>2</sub>Por
and TTF-Ph-pyâAlPor-Ph-H<sub>2</sub>Por). Time-resolved studies
revealed that the AlPor in dyad and triads undergoes photoinduced
energy and/or electron transfer processes. Interestingly, the energy
and electron donating/accepting nature of AlPor can be modulated by
changing the solvent polarity or by stimulating a new competing process
using a TTF molecule. In modest polar solvents (dichloromethane and <i>o</i>-dichlorobenzene), excitation of AlPor leads singletâsinglet
energy transfer from the excited singlet state of AlPor (<sup>1</sup>AlPor*) to H<sub>2</sub>Por with a moderate rate constant (<i>k</i><sub>EnT</sub>) of 1.78 Ă 10<sup>8</sup> s<sup>â1</sup>. In contrast, excitation of AlPor in the triad results in ultrafast
electron transfer from TTF to <sup>1</sup>AlPor* with a rate constant
(<i>k</i><sub>ET</sub>) of 8.33 Ă 10<sup>9</sup>â1.25
Ă 10<sup>10</sup> s<sup>â1</sup>, which outcompetes the
energy transfer from <sup>1</sup>AlPor* to H<sub>2</sub>Por and yields
the primary radical pair TTF<sup>+â˘</sup>-AlPor<sup>ââ˘</sup>-H<sub>2</sub>Por. A subsequent electron shift to H<sub>2</sub>Por
generates a spatially well-separated TTF<sup>+â˘</sup>-AlPor-H<sub>2</sub>Por<sup>ââ˘</sup> radical pair
Charge Stabilization in High-Potential Zinc Porphyrin-Fullerene via Axial Ligation of Tetrathiafulvalene
Extending
the lifetime of the charge-separated states generated
during photoinduced electron transfer in a covalently linked high-potential
zinc porphyrin-fullerene dyad, (F<sub>15</sub>P)ÂZnâC<sub>60</sub>, was accomplished by metalâligand axial coordination of pyridine-functionalized
tetrathiafulvalene (TTF) via a dual-electron-transfer/hole migration
mechanism. The <i>meso</i>-aryl positions of the zinc porphyrin
carried three penta-fluorophenyl substituents that made the zinc porphyrin
ring harder to oxidize by 0.43 V compared with zinc porphyrin with <i>meso</i>-phenyl substituents. Two TTF derivatives, a first with
a pyridine directly linked to TTF (Py-TTF) and a second with a phenyl
spacer between the pyridine and TTF (Py-phTTF), were employed to vary
the distance between the primary photosensitizer/electron donor, zinc
porphyrin, and the secondary electron donor, TTF. Both Py-TTF and
Py-phTTF coordinated via the pyridine entity to the Zn center with
1:1 molecular stoichiometry and moderate binding constants. The supramolecular
triads were characterized by optical absorption and emission, electrochemistry,
and computational studies. An energy-level diagram was established
to realize the different photochemical events in the triads. Using
femtosecond transient absorption spectroscopy, it was possible to
show that the coordinated TTF participated in electron transfer from
the <sup>1</sup>(F<sub>15</sub>P)ÂZn* in the case of the C<sub>60</sub>-(F<sub>15</sub>P)ÂZn:TTF triads to produce C<sub>60</sub>-(F<sub>15</sub>P)ÂZn<sup>â˘â</sup>:TTF<sup>â˘+</sup> charge-separated
state competitively with the electron transfer from the <sup>1</sup>(F<sub>15</sub>P)ÂZn* to covalently linked C<sub>60</sub> to produce
C<sub>60</sub><sup>â˘â</sup>-(F<sub>15</sub>P)ÂZn<sup>â˘+</sup>:TTF charge-separated state. The two charge-separated
states, C<sub>60</sub>-(F<sub>15</sub>P)ÂZn<sup>â˘â</sup>:TTF<sup>â˘+</sup> and C<sub>60</sub><sup>â˘â</sup>-(F<sub>15</sub>P)ÂZn<sup>â˘+</sup>:TTF, were further involved
in electron migration in the former case and hole transfer in the
latter case to produce the C<sub>60</sub><sup>â˘â</sup>-(F<sub>15</sub>P)ÂZn:TTF<sup>â˘+</sup> charge-separated state
as the ultimate electron-transfer product. Due to distal separation
of the positive and negative radical ions, long-lived charge-separated
states persistent for about 0.35 Îźs was possible to accomplish,
as shown by nanosecond transient absorption spectral studies
Interfacial Electron Transfer Followed by Photooxidation in <i>N</i>,<i>N</i>âBis(<i>p</i>âanisole)aminopyridineâAluminum(III) PorphyrinâTitanium(IV) Oxide Self-Assembled Photoanodes
Two
self-assembled photoanodes have been constructed by exploiting
the unique optical and structural properties of aluminumÂ(III) porphyrin
(AlPor) in conjunction with TiO<sub>2</sub> nanoparticles as an electron
acceptor and bisÂ(<i>p</i>-anisole)Âaminopyridine (BAAâPy)
as an electron donor. AlPor is bound to the TiO<sub>2</sub> surface
by either: (i) a benzohydroxamic acid bridge, in which the hydroxamic
acid acts as an anchor or (ii) direct covalent binding of Al via an
ether bond. The open sixth coordination site of the Al center is then
used to coordinate BAAâPy through Lewis acidâbase interactions,
which results in donorâphotosensitizerâsemiconductor
constructs that can be used as photoanodes. The two photoanodes were
characterized by steady-state and transient spectroscopic techniques
as well as computational methods. Transient-absorption studies show
that in the absence of BAAâPy both the photoanodes exhibit
electron injection from AlPor to the conduction band of TiO<sub>2</sub>. However, the injection efficiencies and kinetics are strongly dependent
on the linker with faster and more efficient injection occurring when
the porphyrin is directly bound. Kinetic results also suggest that
the recombination is faster in directly bound AlPor than benzohydroxamic
acid bridged AlPor. When BAAâPy is coordinated to AlPor, electron
injection from AlPor to TiO<sub>2</sub> is followed by electron transfer
from BAAâPy to the oxidized AlPor. The injection efficiencies
modeled using density functional theory and semiempirical tight-binding
calculations are consistent with experimentally observed trends