405 research outputs found
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Electronic structures and nonlinear optical properties of macrocycles in model compounds and in photosynthetic systems
Ultrafast energy and electron transfer processes are carried out in natural photosynthetic systems via chlorophyll molecules attached to proteins. The chlorophyll molecules are held by the protein matrices with different relative distances and orientations. The environment around each chlorophyll determines its energetics and function in initial photochemical reactions. One of the most important factors that modify the energetics of the chlorophylls is the electronic interactions between the chlorophylls. This has been demonstrated by the structural details of the two chlorophyll arrays, B800 and B850 in photosynthetic bacterial antenna LHII, as well as the special pair chlorophylls in the bacterial photosynthetic reaction center. The former conducts the energy transfer to LFI, then to the reaction center, the latter, the electron transfer. The electronic interactions between chlorophylls in model systems and natural photosynthetic systems have been studied extensively with various techniques, e.g., linear optical absorption, but the nonlinear optical properties, such as high order nonlinear optical susceptibilities, are not well characterized. In this study, we intend to characterize the nonlinear optical susceptibility {Chi} in various molecular systems consisting of chlorophyll, porphyrin and phthalocyanine with different configurations and aggregation states. The goal of this research is twofold, (1) to establish the correlation between the electronic couplings in macrocycles and {Chi} with experimental measurements (e.g., degenerated four wave mixing, DFWM) and theoretical modeling, and (2) to explore the potential applications of biophotonics device based on the {Chi} measurements of various chlorophyll arrays which perform ultrafast energy and electron transfer similar to those desirable functions in photonic devices
Synergistic therapeutic effect of arsenic trioxide and radiotherapy in BALB/C nude mice bearing nasopharyngeal carcinoma xenografts
It has been shown that arsenic trioxide (ATO) induced apoptosis in human nasopharyngeal carcinoma cells and inhibited the growth of nasopharyngeal carcinoma xenografts (NPCX) in nude mice. Aim: The present study was designed to determine whether ATO at the non-toxic dose level could potentiate the therapeutic effectiveness of radiation therapy in nasopharyngeal carcinoma, using a BALB/C nude mouse xenograft model. Methods: The mice bearing NPCX were treated with radiation alone (2, 4, and 6 Gy), ATO alone (4 mg/kg/day x 6 days), and ATO plus radiation at the same dosage levels. Time of tumor growth delay (defined as the time necessary for the tumor to grow four-fold of its initial volume after, compared with untreated tumors) and toxic effects were determined. Results: The low dose ATO alone has no pronounced effects on tumor growth delay compared to untreated control. However, compared with radiation alone, the combined regimen delayed the tumor growth by 2β10 days and had no significant toxic effects such as the liver function damage. Conclusions: Combination of ATO at non-toxic dose level and radiation has synergistic effects on tumor growth inhibition in vivo and is well tolerated.Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ ΡΡΠΈΠΎΠΊΡΠΈΠ΄ ΠΌΡΡΡΡΠΊΠ° (Π’ΠΠ) ΠΈΠ½Π΄ΡΡΠΈΡΡΠ΅Ρ Π°ΠΏΠΎΠΏΡΠΎΠ· Π² ΠΊΠ»Π΅ΡΠΊΠ°Ρ
ΠΊΠ°ΡΡΠΈΠ½ΠΎΠΌΡ Π½ΠΎΡΠΎΠ³Π»ΠΎΡΠΊΠΈ ΡΠ΅Π»ΠΎΠ²Π΅ΠΊΠ° ΠΈ ΠΈΠ½Π³ΠΈΠ±ΠΈΡΡΠ΅Ρ
ΡΠΎΡΡ ΠΊΡΠ΅Π½ΠΎΠ³ΡΠ°ΡΡΠ° ΠΊΠ°ΡΡΠΈΠ½ΠΎΠΌΡ Π½ΠΎΡΠΎΠ³Π»ΠΎΡΠΊΠΈ Ρ Π°ΡΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΌΡΡΠ΅ΠΉ. Π¦Π΅Π»Ρ ΡΠ°Π±ΠΎΡΡ β ΡΡΡΠ°Π½ΠΎΠ²ΠΈΡΡ ΡΠ΅ΡΠ°ΠΏΠ΅Π²ΡΠΈΡΠ΅ΡΠΊΡΡ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ
ΡΠ°Π΄ΠΈΠΎΡΠ΅ΡΠ°ΠΏΠΈΠΈ Π² ΠΊΠΎΠΌΠ±ΠΈΠ½Π°ΡΠΈΠΈ Π’ΠΠ Π² Π½Π΅ΡΠΎΠΊΡΠΈΡΠ½ΠΎΠΉ Π΄ΠΎΠ·Π΅ ΠΌΡΡΠ°ΠΌ Π»ΠΈΠ½ΠΈΠΈ BALB/ Ρ ΠΊΡΠ΅Π½ΠΎΠ³ΡΠ°ΡΡΠΎΠΌ ΠΊΠ°ΡΡΠΈΠ½ΠΎΠΌΡ Π½ΠΎΡΠΎΠ³Π»ΠΎΡΠΊΠΈ.
ΠΠ΅ΡΠΎΠ΄Ρ: ΠΆΠΈΠ²ΠΎΡΠ½ΡΠ΅ Ρ ΠΊΡΠ΅Π½ΠΎΠ³ΡΠ°ΡΡΠΎΠΌ ΠΊΠ°ΡΡΠΈΠ½ΠΎΠΌΡ Π½ΠΎΡΠΎΠ³Π»ΠΎΡΠΊΠΈ ΠΏΠΎΠ»ΡΡΠ°Π»ΠΈ Π»ΠΈΠ±ΠΎ ΡΠΎΠ»ΡΠΊΠΎ ΡΠ°Π΄ΠΈΠΎΡΠ΅ΡΠ°ΠΏΠΈΡ (2, 4 ΠΈ 6 ΠΡ) ΠΈΠ»ΠΈ Π’ΠΠ
(4 ΠΌΠ³/ΠΊΠ³/Π΄Π΅Π½Ρ Π² ΡΠ΅ΡΠ΅Π½ΠΈΠ΅ 6 Π΄Π½Π΅ΠΉ), ΠΈΠ»ΠΈ ΠΈΡ
ΠΊΠΎΠΌΠ±ΠΈΠ½Π°ΡΠΈΡ Π² ΡΠ΅Ρ
ΠΆΠ΅ ΡΠ΅ΠΆΠΈΠΌΠ°Ρ
ΠΈ Π΄ΠΎΠ·Π°Ρ
. ΠΠ°Π΄Π΅ΡΠΆΠΊΡ ΡΠΎΡΡΠ° ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ»ΠΈ ΠΊΠ°ΠΊ
ΡΠ°Π·Π»ΠΈΡΠΈΠ΅ Π²ΠΎ Π²ΡΠ΅ΠΌΠ΅Π½ΠΈ, Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠΎΠΌ Π΄Π»Ρ Π΄ΠΎΡΡΠΈΠΆΠ΅Π½ΠΈΡ ΠΎΠΏΡΡ
ΠΎΠ»ΡΡ 4-ΠΊΡΠ°ΡΠ½ΠΎΠ³ΠΎ ΠΎΠ±ΡΠ΅ΠΌΠ° ΠΏΠΎ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ Ρ Π½Π°ΡΠ°Π»ΡΠ½ΡΠΌ ΠΎΠ±ΡΠ΅ΠΌΠΎΠΌ Π²
ΠΎΠΏΡΡΠ½ΠΎΠΉ Π³ΡΡΠΏΠΏΠ΅ versus ΡΠ°ΠΊΠΎΠ²ΠΎΠ³ΠΎ Π² ΠΊΠΎΠ½ΡΡΠΎΠ»ΡΠ½ΠΎΠΉ Π³ΡΡΠΏΠΏΠ΅. Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ: Π²Π²Π΅Π΄Π΅Π½ΠΈΠ΅ Π’ΠΠ Π² Π½ΠΈΠ·ΠΊΠΎΠΉ Π΄ΠΎΠ·Π΅ Π½Π΅ ΠΎΠΊΠ°Π·ΡΠ²Π°Π»ΠΎ Π²ΡΡΠ°ΠΆΠ΅Π½Π½ΠΎΠ³ΠΎ
Π²Π»ΠΈΡΠ½ΠΈΡ Π½Π° ΡΠΎΡΡ ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ ΠΏΠΎ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ Ρ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»ΡΠΌΠΈ Π² ΠΊΠΎΠ½ΡΒΡΠΎΠ»ΡΠ½ΠΎΠΉ Π³ΡΡΠΏΠΏΠ΅, Π° Π² ΠΊΠΎΠΌΠ±ΠΈΠ½Π°ΡΠΈΠΈ Ρ ΠΎΠ±Π»ΡΡΠ΅Π½ΠΈΠ΅ΠΌ ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΠ»ΠΎ
ΠΊ Π·Π°Π΄Π΅ΡΠΆΠΊΠ΅ ΡΠΎΡΡΠ° ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ Π½Π° 2β12 ΡΡΡ ΠΏΠΎ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ Ρ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»ΡΠΌΠΈ Ρ ΠΆΠΈΠ²ΠΎΡΠ½ΡΡ
, ΠΏΠΎΠ»ΡΡΠ°Π²ΡΠΈΡ
ΡΠΎΠ»ΡΠΊΠΎ Π»ΡΡΠ΅Π²ΡΡ ΡΠ΅ΡΠ°ΠΏΠΈΡ
ΠΏΡΠΈ ΠΎΡΡΡΡΡΡΠ²ΠΈΠΈ Π²ΡΡΠ°ΠΆΠ΅Π½Π½ΡΡ
ΠΏΠΎΠ±ΠΎΡΠ½ΡΡ
ΡΡΡΠ΅ΠΊΡΠΎΠ². ΠΡΠ²ΠΎΠ΄Ρ: ΠΊΠΎΠΌΠ±ΠΈΠ½Π°ΡΠΈΡ Π’ΠΠ Π² Π½Π΅ΡΠΎΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠΉ Π΄ΠΎΠ·Π΅ ΠΈ Π»ΡΡΠ΅Π²ΠΎΠΉ ΡΠ΅ΡΠ°ΠΏΠΈΠΈ
ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ ΠΈΠ½Π³ΠΈΠ±ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΠΎΡΡΠ° ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ in vivo ΠΈ Π½Π΅ Π²ΡΠ·ΡΠ²Π°Π΅Ρ ΠΏΠΎΠ±ΠΎΡΠ½ΡΡ
ΡΡΡΠ΅ΠΊΡΠΎΠ².
ΠΠ»ΡΡΠ΅Π²ΡΠ΅ ΡΠ»ΠΎΠ²Π°: ΡΡΠΈΠΎΠΊΡΠΈΠ΄ ΠΌΡΡΡΡΠΊΠ°, ΡΠ°Π΄ΠΈΠΎΡΠ΅ΡΠ°ΠΏΠΈΡ, ΠΊΡΠ΅Π½ΠΎΠ³ΡΠ°ΡΡ ΠΊΠ°ΡΡΠΈΠ½ΠΎΠΌΡ Π½ΠΎΡΠΎΠ³Π»ΠΎΡΠΊΠΈ
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Molecular structure determination for photogenerated intermediates in photoinduced electron transfer reactions using steady-state and transient XAFS
Many photoinduced electron transfer reactions are accompanied by nuclear rearrangements of the molecules involved. In order to understand the reactivities of the molecules and the reaction mechanisms, precise information on the molecular structural changes accompanying the electron transfer is often required. We present here conventional XAFS and transient energy dispersive XAFS studies on structures of excited and photoinduced charge separated state of porphyrin and porphyrin based supermolecules, and structures of TiO{sub 2} colloid and the heavymetal ions that bind to the colloid surfaces during photocatalytic reductions
Preparation, characterization and anti-ageing activity of Gastrodia elata blume polysaccharide
Gastrodia elata Blume polysaccharide (GEP) was extracted and then chemically characterised. Its antioxidant activity was evaluated in vitro and in vivo. The results of the in vitro investigation show that GEP consists of glucose with molecular weight of 875 185 Da and exhibits high hydroxyl radical scavenging, as well as 2,2-diphenyl-1- picrylhydrazyl activity and reducing capacity. For antioxidant activity in vivo, D-galactose-induced-aged mice were orally administered with three different doses of GEP over a period of 6 weeks. The administration of GEP dosedependently increased the body weight gain rates, liver and brain indices, superoxide dismutase and glutathione peroxidase activities, and malondialdehyde levels in the sera and brains of ageing mice. These results suggest that GEP exhibits high antioxidant activity and can retard human ageing associated with free radicals
Crystal Structure, Infrared Spectra, and Microwave Dielectric Properties of Temperature-Stable Zircon-Type (Y,Bi)VO<inf>4</inf> Solid-Solution Ceramics
A series of (Bi 1-x Y x )VO 4 (0.4 β€ x β€ 1.0) ceramics were synthesized using the traditional solid-state reaction method. In the composition range of 0.4 β€ x β€ 1.0, a zircon-type solid solution was formed between 900 and 1550 Β°C. Combined with our previous work (scheelite monoclinic and zircon-type phases coexist in the range of x < 0.40), a pseudobinary phase diagram of BiVO 4 -YVO 4 is presented. As x decreased from 1.0 to 0.40, the microwave permittivity (Ο΅ r ) of (Bi 1-x Y x )VO 4 ceramics increased linearly from 11.03 to 30.9, coincident with an increase in the temperature coefficient of resonant frequency (TCF) from -61.3 to +103 ppm/Β°C. Excellent microwave dielectric properties were obtained for (Bi 0.3 Y 0.7 )VO 4 sintered at 1025 Β°C and (Bi 0.2 Y 0.8 )VO 4 sintered at 1075 Β°C with Ο΅ r βΌ 19.35, microwave quality factor (Qf) βΌ 25 760 GHz, and TCF βΌ +17.8 ppm/Β°C and Ο΅ r βΌ 16.3, Qf βΌ 31 100 GHz, and TCF βΌ -11.9 ppm/Β°C, respectively. Raman spectra, Shannon's additive rule, a classical oscillator model, and far-infrared spectra were employed to study the structure-property relations in detail. All evidence supported the premise that Bi-based vibrations dominate the dielectric permittivity in the microwave region
A strong steric hindrance effect on ground state, excited state, and charge separated state properties of a CuI-diimine complex captured by X-ray transient absorption spectroscopy
Steady-state and transient structures of a copper diimine dye sensitizer on TiO2 nanoparticles undergoing photoinduced interfacial electron transfer are determined.</p
Rotating day and night disturb growth hormone secretion profiles, body energy metabolism, and insulin levels in mice
Background: Insulin and growth hormone (GH) - 2 vital metabolic regulatory hormones - regulate glucose, lipid, and energy metabolism. These 2 hormones determine substrate and energy metabolism under different living conditions. Shift of day and night affects the clock system and metabolism probably through altered insulin and GH secretion. Methods: Five-week-old male mice were randomly assigned to a rotating light (RL) group (3-day normal light/dark cycle followed by 4-day reversed light/dark cycle per week) and normal light (NL) group. Body weight and food intake were recorded every week. Series of blood samples were collected for pulsatile GH analysis, glucose tolerance test, and insulin tolerance test at 9, 10, and 11 weeks from the start of intervention, respectively. Indirect calorimetric measurement was performed, and body composition was tested at 12 weeks. Expressions of energy and substrate metabolism-related genes were evaluated in pituitary and liver tissues at the end of 12-week intervention. Results: The RL group had an increased number of GH pulsatile bursts and reduced GH mass/burst. RL also disturbed the GH secretion regularity and mode. It suppressed insulin secretion, which led to a disturbed insulin/GH balance. It was accompanied by the reduced metabolic flexibility and modified gene expression involved in energy balance and substrate metabolism. Indirect calorimeter recording revealed that RL decreased the respiratory exchange ratio (RER) and oxygen consumption at the dark phase, which resulted in an increase in fat mass and free fatty acid levels in circulation. Conclusion: RL disturbed pulsatile GH secretion and decreased insulin secretion in male mice with significant impairment in energy, substrate metabolism, and body composition.Diabetes mellitus: pathophysiological changes and therap
The superconductivity at 18 K in LiFeAs system
A new iron arsenide superconducting system LiFeAs was found that crystallizes
into a tetragonal structure with space group P4/nmm. The superconductivity with
Tc up to 18 K was observed in the compounds. This simple 111 type layered iron
arsenide superconductor can be viewed as an analogue of the infinite layer
structure of copper oxides.Comment: 11 pages 3 Figure
PL-03 Harnessing multidrug resistance gene expression for effective antifungal strategies by a natural product berberine
Carbon nanotubes adhesion and nanomechanical behavior from peeling force spectroscopy
Applications based on Single Walled Carbon Nanotube (SWNT) are good example
of the great need to continuously develop metrology methods in the field of
nanotechnology. Contact and interface properties are key parameters that
determine the efficiency of SWNT functionalized nanomaterials and nanodevices.
In this work we have taken advantage of a good control of the SWNT growth
processes at an atomic force microscope (AFM) tip apex and the use of a low
noise (1E-13 m/rtHz) AFM to investigate the mechanical behavior of a SWNT
touching a surface. By simultaneously recording static and dynamic properties
of SWNT, we show that the contact corresponds to a peeling geometry, and
extract quantities such as adhesion energy per unit length, curvature and
bending rigidity of the nanotube. A complete picture of the local shape of the
SWNT and its mechanical behavior is provided
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