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The applications of pyridines and their benzo derivatives, during the last decade are described together with natural products containing pyridine ring systems. The applications are classified into three categories: biological, chemical, and performance. Performance applications based on physical properties of pyridines and their benzo-derived compounds, describes dyes, flavor and fragrances, and ionic liquids. Chemical applications, based on the chemical properties of pyridines and benzo derivatives, describe reagents in analytical chemistry as well as catalysts and reagents in organic synthesis. Pyridine polymers are discussed in a separate section. Biological applications based on bioactivity of pyridine compounds, are further elaborated in sections on pharmaceuticals, agrochemicals, and veterinary products.

Previous studies on reactivity controlled compression ignition combustion indicated that, reducing the hydrocarbon and carbon monoxide emissions at low load conditions still remains a challenge because of lower in-cylinder temperatures due to lower global reactivity gradient and reduced oxidation process. Research in this direction has not been reported so far and with this motivation, an attempt has been made to increase the global reactivity gradient and oxidation of fuel–air mixture by converting the low reactivity fuel methanol into medium reactivity fuel. This is achieved by mixing high octane oxygenated fuel, methanol (Octane Number: 110), with an oxygenated better cetane and volatility fuels like polyoxymethylene dimethyl ether (Cetane Number: 78) and isobutanol (Cetane Number: 15). The medium reactivity fuel with multiple direct injection of diesel fuel timed the combustion of dual fuel–air mixture to avoid too late or too advanced combustion which are the prime factors in controlling the unburnt emissions in a low temperature combustion process. Four medium reactivity fuel samples, M80IB20, M60IB40, M90P10, and M80P20, on percentage volume basis have been prepared and tested on the modified on-road three-cylinder turbocharged common rail direct injection diesel engine to demonstrate higher indicated thermal efficiency and potential reduction in unburnt and oxides of nitrogen/particulate matter emissions from reactivity controlled compression ignition combustion. Experimental results show that, use of medium reactivity fuel with optimized diesel injection strategy resulted in 66% decrease in hydrocarbon emission and 74% decrease in carbon monoxide emission by enhancing the oxidation of fuel–air mixture at lower temperatures which is evidently noticed in the combustion characteristics. Further reduction in hydrocarbon and carbon monoxide emission of about 90% has been achieved by integrating the diesel oxidation catalyst with the engine.

Pure and cobalt (Co)-doped tin oxide (SnO2) nanoparticles were prepared by using a simple co-precipitation method, and the effect of doping on structural, morphological and optical properties was studied. X-ray diffraction revealed a cassiterite tetragonal SnO2 structure with the space group of P42/mnm and without crystalline phases for the samples-doped with higher concentrations. The average crystalline size was found to be between 26.4 nm and 23.1 nm. Fourier-transform infrared spectra depicted the presence of O–H, C–H and Sn–OH absorption bands. It was observed from ultraviolet–visible spectra that the optical band gap values were decreased from 3.69 eV for pure SnO2 to 3.47 eV for 7% Co-doped SnO2. The photolumenescene emission spectra showed that the defect- and emissions-related peaks and the intensity of the peaks decreased with increasing Co concentrations. The presence of tin, oxygen and Co species were found from energy dispersive x-ray spectra. The photocatalytic activities of pure and Co-doped SnO2 nanoparticles were investigated by studying the photodecomposition of brilliant green dye, an organic pollutant. The 7% Co-doped SnO2 had higher photocatalytic activity compared to the pure SnO2, and a maximum degradation efficiency of 91% has been obtained under visible light irradiation.

We develop a lattice model of site-specific DNA-protein interactions under in vivo conditions where DNA is modelled as a self-avoiding random walk that is embedded in a cubic lattice box resembling the living cell. The protein molecule searches for its cognate site on DNA via a combination of three dimensional (3D) and one dimensional (1D) random walks. Hopping and intersegmental transfers occur depending on the conformational state of DNA. Results show that the search acceleration ratio (= search time in pure 3D route/search time in 3D and 1D routes) asymptotically increases towards a limiting value as the dilution factor of DNA (= volume of the cell/the volume of DNA) tends towards infinity. When the dilution ratio is low, then hopping and intersegmental transfers significantly enhance the search efficiency over pure sliding. At high dilution ratio, hopping does not enhance the search efficiency much since under such situation DNA will be in a relaxed conformation that favors only sliding. In the absence of hopping and intersegmental transfers, there exists an optimum sliding time at which the search acceleration ratio attains a maximum in line with the current theoretical results. However, existence of such optimum sliding length disappears in the presence of hopping. When the DNA is confined in a small volume inside the cell resembling a natural cell system, then there exists an optimum dilution and compression ratios (= total cell volume/volume in which DNA is confined) at which the search acceleration factor attains a maximum especially in the presence of hopping and intersegmental transfers. These optimum values are consistent with the values observed in the Escherichia coli cell system. In the absence of confinement of DNA, position of the specific binding site on the genomic DNA significantly influences the search acceleration. However, such position dependent changes in the search acceleration ratio will be nullified in the presence of hopping and intersegmental transfers especially when the DNA is confined in a small volume that is embedded in an outer cell.

Highly transparent and conducting samarium doped cadmium oxide (CdO: Sm) thin films were deposited on glass substrates at room temperature by radio frequency (RF) magnetron sputtering technique using CdO(90 wt%): Sm2O3(10 wt%) mixed alloy target in pure argon atmosphere. The influences of RF power and Sm incorporation on structural, morphological, optical and electrical properties of the films were investigated. X-ray diffraction analysis revealed that the deposited films are polycrystalline nature and RF power has a large impact on the preferred orientation of the films. The X-ray photoelectron spectroscopy studies confirmed the presence of divalent cadmium (Cd2+) and trivalent samarium (Sm3+) in the deposited film. It is found from the atomic force microscopic analysis that the films were highly smooth with low roughness value of about1.3 nm. High transmittance value greater than 80% was retained by the films in visible and near infrared regions and the band gap value decreased with the increase of RF power by quantum confinement. At the moderate RF power of 200 W, the film has low resistivity of the order of 1.283 × 10−4 Ω cm, high mobility 157.8 cm2/V and a high figure of merit 769.04 (Ω cm2)−1 which could be used as an alternative TCO layer for future optoelectronic devices.

Transparent and conducting cadmium oxide (CdO) thin films were deposited on glass substrates at room temperature using radio frequency (RF) magnetron sputtering method. The carrier concentration and electron mobility are the key factors for the conducting properties of CdO thin films. The grain size, crystallinity, thickness, surface roughness and band gap of CdO thin films play an important role in optical and electrical properties. In this study, dual behaviour of CdO thin films is studied as a function of RF sputtering power. Crystalline quality, micro structure, surface morphology and optical and electrical properties of sputtered CdO thin films were investigated. The structural analysis revealed that the deposited CdO films were polycrystalline in nature with cubic structure ( Fm 3 ¯ m space group). The grain sizes were found to be increased with increase of RF power from 100 to 150 W and then decreased at high power (200 W). The optical studies revealed that all the films exhibited higher transmittance in visible and near infrared region and the optical energy band gap value decreased from 2.62 to 2.46 eV with increase of RF power. Luminescence spectra exhibited two strong emission peaks at 484 and 519 nm. The resistivity of CdO thin films gradually decreased with an increase of sputtering power and reached a minimum value of 3.041 × 10−4 Ω cm at 200 W. A maximum mobility of 67.01 cm2/Vs was found for the sample prepared at the sputtering power of 150 W.

Magnetite thin films were deposited by varying the temperature of the bath in the SILAR deposition process. Structural, morphological and optical properties of the deposited films were analyzed using X-ray diffraction, Raman spectroscopy, Field emission scanning electron microscopy, UV–Visible spectroscopy. With the increase in bath temperature of the deposition process, crystallite size decreases and dislocation density and microstrain increases. Raman spectra confirm the formation of magnetite phase for all the deposited films. FESEM images reveal the bath temperature’s influence on the surface morphology. Considerable variations in the optical properties were observed for the films and were discussed in detail.

A novel electrochemical sensor has been fabricated using Co doped CeO2 nanoparticles for selective and simultaneous determination of xanthine (XA), hypoxanthine (HXA) and uric acid (UA) in a phosphate buffer solution (PBS, pH5.0) for the first time. The Co-CeO2 NPs have been prepared by microwave irradiation method and characterized by Powder XRD, Raman spectroscopy, HRTEM and VSM measurements. The electrochemical behaviours of XA, HXA and UA at the Co-CeO2 NPs modified glassy carbon electrode (GCE) were studied by cyclic voltammetry and square wave voltammetry methods. The modified electrode exhibited remarkably well-separated anodic peaks corresponding to the oxidation of XA, HXA and UA over the concentration range of 0.1-1000, 1-600 and 1-2200μM with detection limits of 0.096, 0.36, and 0.12μM (S/N=3), respectively. For simultaneous detection by synchronous change of the concentrations of XA, HXA and UA, the linear responses were in the range of 1-400μM each with the detection limits of 0.47, 0.26, and 0.43μM (S/N=3), respectively. The fabricated sensor was further applied to the detection of XA, HXA and UA in human urine samples with good selectivity and high reproducibility.

DD-carboxypeptidases (DD-CPases) are low-molecular-mass (LMM) penicillin-binding proteins (PBPs) that are mainly involved in peptidoglycan remodelling, but little is known about the dd-CPases of mycobacteria. In this study, a putative DD-CPase of Mycobacterium smegmatis, MSMEG_2433 is characterized. The gene for the membrane-bound form of MSMEG_2433 was cloned and expressed in Escherichia coli in its active form, as revealed by its ability to bind to the Bocillin-FL (fluorescent penicillin). Interestingly, in vivo expression of MSMEG_2433 could restore the cell shape oddities of the septuple PBP mutant of E. coli, which was a prominent physiological characteristic of DD-CPases. Moreover, expression of MSMEG_2433 in trans elevated beta-lactam resistance in PBP deletion mutants (ΔdacAdacC) of E. coli, strengthening its physiology as a dd-CPase. To confirm the biochemical reason behind such physiological behaviours, a soluble form of MSMEG_2433 (sMSMEG_2433) was created, expressed and purified. In agreement with the observed physiological phenomena, sMSMEG_2433 exhibited DD-CPase activity against artificial and peptidoglycan-mimetic DD-CPase substrates. To our surprise, enzymic analyses of MSMEG_2433 revealed efficient deacylation for beta-lactam substrates at physiological pH, which is a unique characteristic of beta-lactamases. In addition to the MSMEG_2433 active site that favours dd-CPase activity, in silico analyses also predicted the presence of an omega-loop-like region in MSMEG_2433, which is an important determinant of its beta-lactamase activity. Based on the in vitro, in vivo and in silico studies, we conclude that MSMEG_2433 is a dual enzyme, possessing both DD-CPase and beta-lactamase activities.

We show that nucleosomes can efficiently control the relative search times spent by transcription factors (TFs) on one- (1D) and three-dimensional (3D) diffusion routes towards locating their cognate sites on DNA. Our theoretical results suggest that the roadblock effects of nucleosomes are dependent on the relative position on DNA with respect to TFs and their cognate sites. Especially, nucleosomes exert maximum amount of hindrance to the 1D diffusion dynamics of TFs when they are positioned in between TFs and their cognate sites. The effective 1D diffusion coefficient (χTF) associated with the dynamics of TFs in the presence of nucleosome decreases with the free energy barrier (µ) associated the sliding dynamics of nucleosomes as . Subsequently the mean first passage time (ηL) that is required by TFs to scan L number of binding sites on DNA via 1D diffusion increases with μ as . When TFs move close to nucleosomes then they exhibit a typical sub-diffusive dynamics. Nucleosomes can enhance the search dynamics of TFs when TFs present in between nucleosomes and transcription factor binding sites (TFBS). The level of enhancement effects of nucleosomes seems to be much lesser than the level of retardation effects when nucleosomes present in between TFs and their cognate sites. These results suggest that nucleosome depleted regions around the cognate sites of TFs is mandatory for an efficient site-specific interactions of TFs with DNA. Remarkably the genome wide positioning pattern of TFs shows maximum at their specific binding sites and the positioning pattern of nucleosome shows minimum at the specific binding sites of TFs under in vivo conditions. This seems to be a consequence of increasing level of breathing dynamics of nucleosome cores and decreasing levels of fluctuations in the DNA binding domains of TFs as they move across TFBS. Since the extent of breathing dynamics of nucleosomes and fluctuations in the DBDs of TFs are directly linked with their respective 1D diffusion coefficients, the dynamics of TFs becomes slow as they approach their cognate sites so that TFs form tight site-specific complex. Whereas the dynamics of nucleosomes becomes rapid so that they pass through the cognate sites of TFs. Several in vivo datasets on genome wide positioning pattern of nucleosomes as well as TFs seem to agree well with our arguments. We further show that the condensed conformational state of DNA can significantly decrease the retarding effects of nucleosome roadblocks. The retarding effects of nucleosomes on the 1D diffusion dynamics of TFs can be nullified when the degree of condensation of the genomic DNA is such that it can permit a jump size associated with the dynamics of TFs beyond k > 150 bps.

This chapter covers the synthesis of heterocyclic compounds using heterogeneous catalysts from the perspective of practicing industrial chemists. Before discussing the synthesis of various heterocycles using heterogeneous catalysts a brief discussion on catalyst choice and classification of reaction chemistry is provided. Next, the synthesis of commercially important heterocycles from acyclic precursors is provided starting with the three-membered aziridines and epoxides. For the four-membered heterocycles, propiolactone synthesis is discussed followed by the five-membered pyrroles, furans, and thiophenes. Within the five-membered ring category of heterocycles, the benz-fused pyrrole, indole and rings with more than one heteroatom such as pyrazoles, imidazoles, thiazoles, oxa- and thio-diazoles synthesis are also discussed. Similar to the five-membered ring heterocycles, the six-membered heterocycle syntheses discussed are pyridines, picolines, quinolines, acridines, pyrimidines, pyrazines, triazines, coumarins, etc. Finally a small section on process and economics consideration is provided along with final comments.

We report a simple and efficient route to synthesize nanoarrows shaped zinc oxide (ZnO) combining electrospinning and high temperature calcination for photocatalytic applications. A comparison of the photo catalytic degradation of methyl orange with ZnO nanoparticles showed that the ZnO nanoarrows were superior to ZnO nanoparticles. These novel ZnO nanoarrows could have wide range of applications such as energy materials, gas sensors, UV–visible blockers and catalyst for organic synthesis.

A hitherto uninvestigated ligno-cellulosic seed fiber from the plant Pergularia Daemia has been chosen for the current study to unravel its physical properties, and potentialities in textile applications. The raw, NaOH treated, and wax removed fibers were tested for their morphological and structural features by X-ray diffraction, SEM, FT-IR spectra, and thermal analysis by thermogravimetry and differential scanning calorimetry. The raw fibers have low cellulose content and less crystalline compared to cotton and are having hollow, smooth surface, and less density. The brittle nature and low elongation at break of virgin fiber makes it difficult for the spinning. It becomes spinnable after NaOH treatment due to the increased elongation at break by partial removal of lignin.

The demand for renewable raw materials is steadily rising as the drive for a green economy and a sustainable future accelerates. Mounting environmental issues and changing attitudes of consumers have made petroleum-based manufactured products more expensive and less desirable in the present world (as of 2016). Utilization of less valuable lignocellulosic fibres that are abundant and do not require irrigation for their cultivation makes them inexpensive and bio-degradable alternatives to petroleum-based synthetic fibres. These fibres are found in dry habitats in the USA, Asia and South Africa and contain over 2000 species worldwide, the properties of which slightly differ as a result of different soil conditions. In recent years, much research has been carried out into potential applications of milkweed fibre due to its incredible characteristics—such as hollowness, low density and hydrophobicity—particularly in technical textiles. The milkweed plant can adapt to almost any soil condition from swampy and moist to sandy and arid. It is a perennial plant and hence, once planted, does not require replanting each season and does not require any fertilizers, making the plant sustainable. Successful commercialization of milkweed as a crop is dependent upon mechanized harvesting, handling, drying and floss-processing systems. This chapter gives comprehensive information about the history of the milkweed plant and fibres, fibre morphology and characteristics, spinnability of milkweed fibres, fabric properties and potential application of milkweed fibres in such areas as clothing, lightweight composites, oil sorption as well as thermal and acoustic insulation.

The performance of ultraviolet protection, antimicrobial activity, soil release action and self-cleaning characteristics of nano zinc oxide (ZnO) with acrylic binder were assessed on the cotton fabric using pad-dry-cure method. Different precursors such as zinc chloride and zinc nitrate were used to synthesize nanoparticles by wet chemical technique. The synthesized nanoparticles were then characterized using Fourier transform infrared spectroscopy, particle size analyser, powder X-ray diffractometry and scanning electron microscopy. The nano ZnO finished cotton fabrics were tested for ultraviolet protection factor, antimicrobial activity, soil release action and self-cleaning action. The wash fastness of nano zinc oxide (ZnO) finished cotton fabrics after 5th, 10th, 15th and 20th washes were assessed. Also the ultraviolet protection factor values, percentage reduction in bacteria and soil release percentage in each washing stage are reported. The self-cleaning activity was assessed for 12, 24and 48 h duration by exposing 6% of coffee stain on the specimen fabrics to sunlight. The zinc oxide nanoparticle size of 24 nm was obtained from synthesis of zinc chloride as a precursor, and another nanoparticle size of 38 nm were obtained from synthesis of zinc nitrate as a precursor. The smaller nanoparticles (24 nm) show better results in terms of antimicrobial activity, soil release and self-cleaning action. In case of ultraviolet protection function, it was found that the fabrics treated with 38 nm nanoparticles exhibit higher ultraviolet protection factor values than the fabric treated with 24 nm nanoparticles. The durability of the imparted functions was in the range 25–38 washes for antimicrobial activity, soil release action and ultraviolet protection, respectively.

In this contribution, we have synthesized series of 1-ethyl-3,5-bis[2-(aryl)ethenyl]-1H-indole based derivatives with different functional groups using Wadsworth–Emmons coupling. The sensing ability of the receptors has been studied for halides like tetrabutylammonium fluoride, chloride, bromide, iodide and bisulphate by UV–vis spectroscopy methods. In THF solution, compound A–E exhibits excellent selectivity with iodide ions over the other ions like tetrabutylammonium bromide (TBABr), tetrabutylammonium chloride (TBACl), tetrabutylammonium fluoride (TBAF) and tetrabutylammonium bisulphate (TBAHSO 4 ). The indole cores were observed effectively and selectively recognized biologically important iodide was reported. Significant absorption change was observed only for tetrabutylammonium iodide and no change with other anions. The absorption spectra indicated the formation of complex between host and guest is in 1:1 stoichiometric ratio. The association constants of A–E for iodide ions were found to be 3.2 × 10 4 M −1 , 3.9 × 10 4 M −1 , 4.2 × 10 3 M −1 , 2.9 × 10 3 M −1 and 2.14 × 10 3 M −1 , respectively.

In this research, the non-formaldehyde wrinkle-resistant treatment of cotton fabrics has been investigated using the citric acid (CA) as a cross-linking agent and sodium hypophosphite (SHP) as a catalyst together with nano-titanium dioxide (nano-TiO2) as a co-catalyst compound. The effect of the changes in the concentrations of CA, SHP, and nano-TiO2 on the wrinkle recovery angle (WRA), tensile strength, tearing strength, whiteness index, and flexural rigidity of cotton fabrics was studied using Box–Behnken design. It was found that the addition of nano-TiO2 could enhance the wrinkle resistance and decrease the flexural rigidity of the cotton fabric with little effect on the whiteness index, and tearing and tensile strengths of the treated fabric. The developed empirical models are found to be in good correlation with the selected variables ( r2 ≥ 0.8). From this study, it was concluded that 10% CA, 10% sodium dihydrogen phosphate, and 0.1% nano-TiO2 were the optimum concentrations required to enhance the WRA without adversely affecting the other physical properties of the treated cotton fabrics.

Geochemical processes that take place in the aquifer have played a major role in spatial and temporal variations of groundwater quality. This study was carried out with an objective of identifying the hydrogeochemical processes that controls the groundwater quality in a weathered hard rock aquifer in a part of Nalgonda district, Andhra Pradesh, India. Groundwater samples were collected from 45 wells once every 2 months from March 2008 to September 2009. Chemical parameters of groundwater such as groundwater level, EC and pH were measured insitu. The major ion concentrations such as Ca2+, Mg2+, Na+, K+, Cl−, and SO42− were analyzed using ion chromatograph. CO3− and HCO3− concentration was determined by acid–base titration. The abundance of major cation concentration in groundwater is as Na+ > Ca2+ > Mg2+ > K+ while that of anions is HCO3− > SO42− > Cl− > CO3−. Ca–HCO3, Na–Cl, Ca–Na–HCO3 and Ca–Mg–Cl are the dominant groundwater types in this area. Relation between temporal variation in groundwater level and saturation index of minerals reveals the evaporation process. The ion-exchange process controls the concentration of ions such as calcium, magnesium and sodium. The ionic ratio of Ca/Mg explains the contribution of calcite and dolomite to groundwater. In general, the geochemical processes and temporal variation of groundwater in this area are influenced by evaporation processes, ion exchange and dissolution of minerals.

Biologically important pyrazolylpyridines were synthesized in excellent yield by the oxidation of pyrazolyl 1,4-dihydropyridines (pyrazolyl 1,4-DHPs) using tetrapropylammonium perruthenate/N-methylmorpholine-N-oxide (TPAP/NMO) under mild conditions at 0 °C.

Electrospinning of a conjugated polymer is not possible due to the absence of chain entanglement (it exists as a rigid rod conformation in a solution), which is a prerequisite for electrospinning. In the present study, fabrication of core–shell nanofibers has been done by co-electrospinning of two components such as poly(3-hexyl thiophene) (P3HT) (a conducting polymer) or P3HT/PCBM as the core and poly(vinyl pyrrolidone) (PVP) as the shell. The TEM observation and FTIR analysis confirmed the encapsulation of the P3HT within the PVP polymer. Continuous P3HT or P3HT/PCBM nanofibers have been obtained by subsequent washing of the shell polymer template in a post-treatment step. These nanofibers were tested for solar cloth applications.

Serious problems are faced in several parts of the world due to the presence of high concentration of fluoride in drinking water which causes dental and skeletal fluorosis to humans. Nalgonda district in Andhra Pradesh, India is one such region where high concentration of fluoride is present in groundwater. Since there are no major studies in the recent past, the present study was carried out to understand the present status of groundwater quality in Nalgonda and also to assess the possible causes for high concentration of fluoride in groundwater. Samples from 45 wells were collected once every 2 months and analyzed for fluoride concentration using an ion chromatograph. The fluoride concentration in groundwater of this region ranged from 0.1 to 8.8 mg/l with a mean of 1.3 mg/l. About 52% of the samples collected were suitable for human consumption. However, 18% of the samples were having less than the required limit of 0.6 mg/l, and 30% of the samples possessed high concentration of fluoride, i.e., above 1.5 mg/l. Weathering of rocks and evaporation of groundwater are responsible for high fluoride concentration in groundwater of this area apart from anthropogenic activities including irrigation which accelerates weathering of rocks.

We generalize the idea of multiple-stochasticity in chemical reaction systems to gene expression. Using Chemical Langevin Equation approach we investigate how this multiple-stochasticity can influence the overall molecular number fluctuations. We show that the main sources of this multiple-stochasticity in gene expression could be the randomness in transcription and translation initiation times which in turn originates from the underlying bio-macromolecular recognition processes such as the site-specific DNA-protein interactions and therefore can be internally regulated by the supra-molecular structural factors such as the condensation/super-coiling of DNA. Our theory predicts that (1) in case of gene expression system, the variances (φ) introduced by the randomness in transcription and translation initiation-times approximately scales with the degree of condensation (s) of DNA or mRNA as φ∝s−6. From the theoretical analysis of the Fano factor as well as coefficient of variation associated with the protein number fluctuations we predict that (2) unlike the singly-stochastic case where the Fano factor has been shown to be a monotonous function of translation rate, in case of multiple-stochastic gene expression the Fano factor is a turn over function with a definite minimum. This in turn suggests that the multiple-stochastic processes can also be well tuned to behave like a singly-stochastic point processes by adjusting the rate parameters.

Renaturation of complementary single strands of DNA is one of the important processes that requires better understanding in the view of molecular biology and biological physics. Here we develop a stochastic dynamical model on the DNA renaturation. According to our model there are at least three steps in the renaturation process viz. incorrect-contact formation, correct-contact formation and nucleation, and zipping. Most of the earlier two-state models combined nucleation with incorrect-contact formation step. In our model we suggest that it is considerably meaningful when we combine the nucleation with the zipping since nucleation is the initial step of zipping and the nucleated and zipping molecules are indistinguishable. Incorrect-contact formation step is a pure three-dimensional diffusion controlled collision process. Whereas nucleation involves several rounds of one-dimensional slithering dynamics of one single strand of DNA on the other complementary strand in the process of searching for the correct-contact and then initiate nucleation. Upon nucleation, the stochastic zipping follows to generate a fully renatured double stranded DNA. It seems that the square-root dependency of the overall renaturation rate constant on the length of reacting single strands originates mainly from the geometric constraints in the diffusion controlled incorrect-contact formation step. Further the inverse scaling of the renaturation rate on the viscosity of the reaction medium also originates from the incorrect-contact formation step. On the other hand the inverse scaling of the renaturation rate with the sequence complexity originates from the stochastic zipping which involves several rounds of crossing over the free-energy barrier at microscopic levels., Comment: 17 pages, 2 figures

A processing method of hydroxy-carbonate apatite (HCAp) from the natural bone and their phase purity, crystal structure, chemical functionality, thermal stability, morphology, and solubility are described in this investigation. The X-ray diffraction analysis suggested that the processed bone corresponds characteristically to carbonate (CO32−) containing hydroxyapatite. Fourier transform infrared spectroscopic study confirmed the presence of CO32− in addition to hydroxyl (OH−) and phosphate (PO43−) functional groups, indicating the formation of HCAp. Environmental scanning electron microscopy was employed to identify the surface morphology of HCAp, which obviously shows a nanoporous structure throughout the matrix. The in vitro solubility study performed under physiological conditions confirms the resorbable nature of HCAp. These findings indicate the feasibility of processing nanoporous HCAp scaffolds from the natural bone by a straightforward method.

Bovine-derived biological apatite has a long history for use in human health care as bone substitute. This article reports an elegant method of designing bovine-derived hydroxyapatite (BHA) blocks suitable for drug delivery. Neomycin sulphate (NS) was selected as a model drug and its loading and release studies were performed under in-vitro physiological conditions. The results indicate that phase purity and structural integrity of the BHA are retained even after entrapment of drug molecules. It was noticed that the rate of neomycin delivery was directly proportional to the porosity of the BHA blocks. The in-vitro release studies suggest that BHA may be used as a good carrier system for neomycin delivery.

The noise in the central process such as transcription, replication and translation of the genomic DNA is very important since it can directly affect the phenotypic and behavioral aspects of an organism as well as the entire cellular function. Here we develop a model on the transcription process based on the assumption that the initiation of the transcription is a stochastic event and the transcription rates may be time dependent random quantities. We derive the central measure properties i.e. mean and the variance, of the distribution of the transcription rates. Our results show that the Fano factor which is a measure of deviation from the Poisson distribution associated with the fluctuations in the number of mRNA molecules deviates from unity due to the randomness in the transcription rates. However when the RNA polymerase molecule searches for the promoter sequences on the DNA lattice by random jumps, the Fano factor approaches the Poisson limit as the jump size associated with the RNA polymerase increases. Since the jump size associated with dynamics of RNAP molecule is positively correlated with the degree of super coiling of DNA, we argue that the super coiled or close-packed structure of DNA might have evolved to keep the noises at the transcriptional level in a minimum.

Putidaredoxin (PdX), the physiological effector of cytochrome P450 cam (P450 cam ), serves to gate electron transfer into oxy-P450 cam during the catalytic cycle of the enzyme. Redox-linked structural changes in PdX are necessary for the effective P450 cam turnover reaction. PdX is believed to be difficult to be replaced by an artificial electron donor in the reaction pathway of P450 cam . We demonstrate that the catalytic cycle of wild-type P450 cam can be supported in the presence of an artificial reductant, potassium ferrocyanide. Upon rapid mixing of ferrocyanide ion with P450 cam , we observed an intermediate with spectral features characteristic of compound I. The rate constant for the formation of compound I in the presence of ferrocyanide supported reaction cycle was found to be comparable to the ones observed for H 2 O 2 supported compound I formation in wild-type P450 cam , but was much lower than those observed for classical peroxidases. The results presented in this paper form the first kinetic analysis of this intermediate for an artificial electron-driven P450 cam catalytic pathway in solution.

Synthetic hydroxyapatite ( Ca 10( PO 4)6( OH )2, HA ) is an important material used for orthopaedic and dental implant applications. The biological hydroxyapatite in the human bone and tooth is of nano size and differs in composition from the stiochiometric HA by the presence of other ions such as carbonate, magnesium and fluoride, etc. Osseointegration is enhanced by using nanocrystalline HA . This stimulates the interest in synthesizing nanocrystalline HA by different routes and among the methods, mechanochemical seems to form fine grain size and uniform characteristic nanocrystalline materials. Fluorinated hydroxyapatite ( FHA , Ca 10( PO 4)6( OH )2-x F x) possesses higher corrosion resistance in biofluids than pure HA and reduces the risk of dental caries. The present work deals with the synthesis of nanocrystalline FHAs by mechanochemical processing. The nanomaterials were characterized using X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) methods. Nano FHA of about 27-46 nm size was observed. The functional groups present in the FHA powders were ascertained by Fourier transform infrared spectroscopy (FT-IR) and Laser Raman spectroscopy. A gradual decrease in intensity of the OH - band at 655 and 3572 cm-1 has been observed with increasing fluorine substitution. The TEM micrograph shows that the powder is highly agglomerated and particle size is below 50 nm.

Affinity (the fastness) and specificity (the correctness) are the two important factors that decide the efficiency of a nucleic acid probe to target its specific site on a DNA lattice. DNA-probe interactions differ from protein-ligand interactions in a way that here the specificity and the affinity of the interactions correlate negatively with each other. We present a simple phenomenological theory to explain the negative correlation between the specificity and the affinity of the probe towards its target site on the template DNA under solution conditions. We show that a simple random jump model can explain this fact and we also predict that the negative correlation between the affinity and specificity diminishes as the temperature increases or the viscosity of the medium decreases. Moreover, the length of target DNA and the distance between the initial position of the probe on the template DNA lattice and the target site increases the magnitude of affinity-specificity negative correlation. These results are consistent with experimental observations. Finally we propose practical strategies to coherently improve the specificity and the affinity with respect to important molecular biological techniques such as PCR and Southern blotting.

Bioresorption and particulate migration of hydroxyl carbonateapatite (HCAp) are the common clinical problems in periodontal osseous defects. In this study, an attempt is made to prepare a hybrid bone composite with chitosan-incorporated HCAp to alleviate the above demerits. The prepared composites are analyzed by various physicochemical methods and the HCAp is found to be well intact in the chitosan macromolecules. Chemical analysis clearly indicates the presence of hydroxyl and amide groups in addition to the characteristic bands of HCAp in the composites. The particle size of the HCAp has increased tremendously with increasing the conjugation of chitosan, which is highly beneficial for the immobilization of HCAp particles upon implantation. Physiological stability and solubility of the bone composites are carried out in vitro in Hank's medium of pH 7.4 in a temperature-controlled incubator and found that the dissolution rate of calcium ions is quite higher in the composites than in HCAp. No structural deformations are detected for HCAp due to the presence of chitosan as evidenced by the X-ray diffraction (XRD) method. These findings suggest that HCAp-chitosan composites can efficiently be used as a bioresorbable bone substitute and the bioresorbability can also be controlled by optimizing the chitosan incorporation. ? 2005 Sage Publications.

Aim of this study concerns to the development of bioresorbable composite materials for bone repair and regeneration. Despite nano hydroxyapatite (HA) has wide range of medical applications, particles mobilization and slow resorbable nature limits its use in certain applications particularly, periodontal and alveolar ridge augmentation. To enhance its usage, we have prepared HA composite bone paste with a natural polysaccharide, chitosan, using wet chemical method at low temperature. The prepared composites were analyzed by various physicochemical methods and suggesting that the nano HA crystallites are well intact with the chitosan macromolecules. FT-IR results are indicating the existence of hydroxyl and amide groups in addition to the characteristic peaks of nano HA in the composite paste. The physical nature of paste form implies that it would be highly beneficial for the particle immobilization upon implantation. In vitro physiological stability and solubility of the composite was performed in phosphate buffered saline under physiological condition and found that the rate of resorbability of composite was quite higher than nano HA. These findings suggest that the HA/chitosan composites may have a great impact on human health care systems as bioresorbable bone substitute.

Surface modification and coupling of therapeutic molecules, tetracycline, onto coralline hydroxyapatite (CHA) and their in vitro evaluations were described in this study. Initially, CHA was graft polymerized with glycidylmethacrylate (GMA) using redox initiators and subsequently coupled to tetracycline through epoxy groups. The CHA grafted with polyGMA (CHA-g-PGMA) was characterized by Fourier transform infrared spectroscopy and powder X-ray diffraction (XRD) for proof of grafting. The absorption peaks pertaining to epoxy and ester carbonyl groups were observed for the graft polymer due to PGMA grafting. The XRD results signified that there was no secondary phase in the apatite lattice and crystallinity was also not affected by grafting, which suggested that the PGMA chains were grafted only on the surface of CHA. Drug loading and releasing was evaluated and found that CHA-g-PGMA exhibited higher loading efficiency than CHA. The in vitro release of tetracycline was performed in phosphate buffered saline under physiological condition and the release profiles showed that the tetracycline-containing graft polymer releases the drug for prolonged period as compared to CHA. Based on the experimental results, CHA-g-PGMA appears to be a promising biomaterial for drug delivery.

Studies on chemical modification of demineralized bone matrix (DBM) have opened new arenas in the field of clinical orthopedics owing to its potential osteoinductivity with desired chemical functionality. To widen its usage to biomolecular delivery, graft polymerization of glycidylmethacrylate onto DBM was carried out by a free-radical initiating process using ceric ammonium nitrate as an initiator. The evidence of the grafting reaction was examined by chemical analysis using Fourier transform IR spectroscopy. The grafting condition was standardized by regulating the reaction parameters such as the concentrations of the backbone, the monomer and the initiator, the polymerization temperature and time. The optimum polymerization temperature and time to have the maximum grafting yield were 40 °C and 3 h, respectively. The percentage of grafting and the percentage of grafting efficiency were determined as a function of the reaction parameters, and both were found to increasing initially and thereafter decrease in most of the cases. The grafting results are discussed in a detailed fashion and a reaction mechanism is proposed.

The effect of 1R-camphor on the conformational stability of the heme active site of cytochrome P450cam has been investigated. The absorption spectra of the heme moiety showed the presence of two hitherto unknown intermediates formed at low urea concentrations or during small temperature perturbations. The corresponding thermodynamic parameters were obtained by global fitting of the experimental data to a generalized sequential unfolding model at different wavelengths, which showed that the active conformation of the enzyme is stabilized by binding of the substrate at the active site. Circular-dichroism spectra of the enzyme in the visible- and far-UV region were studied to identify the critical range of denaturant concentration and the temperature at which the tertiary structure around the heme center was affected with almost no change in the secondary structure of the enzyme. This critical range of urea concentration was 0-2.8 M in the presence of camphor and 0-1.5 M in the absence of camphor. The tertiary structure of the enzyme was found to undergo conformational change in the temperature range 20-60 degrees C in the presence of the substrate and 20-47 degrees C in its absence. The spectral assignments of the intermediate species of the heme active site with the intact secondary structure of the enzyme were made by deconvolution of the Soret absorption spectra, and the results were analyzed to determine stabilization of the heme active-site geometry by 1R-camphor. Results showed that subtle conformational changes due to melting of the tertiary contacts in the active site lead to formation of intermediates which are coordinatively similar to the native enzyme. Analogous intermediate species might be responsible for leakage in the redox catalytic cycle of the enzyme.

Bi-phasic calcium phosphate (BCP) bioceramics containing hydroxyapatite (HA) and tri-calcium phosphate (TCP) phases have recently attracted attention as an ideal bone graft substitute due to their controlled resorption in the body fluid upon implantation. In this study, the HA and BCP phases were prepared by in situ method, using natural goniopora under microwave irradiation. Fourier-transform infrared (FT-IR) and powder X-ray diffraction (XRD) methods were employed to investigate proof of HA and BCP formations. XRD results show that the major characteristic peaks of HA appear in the regions of approximately 26°, 28°, 29°, 30–35°, 39°, 46°, 49° and 50° (2 θ ). FT-IR results indicate that there are no occurrences of impurities during HA and BCP formations. Reinforcement of zirconia in the in situ formation of HA leads to a more resorbable phase of β-TCP since the influence of zirconia induces faster decomposition of HA, as indicated by differential thermal (DT) analysis. The in vitro physiological stability of prepared materials was performed in phosphate-buffered saline (PBS) of pH 7.4 at 37 °C in a thermostatic water bath, and the results indicate that the resorbable nature of BCP lies in between the resorption levels of HA and TCP. Solubility of the BCP can be controlled by the addition of zirconia corresponding to clinical applications.

Theoretical proof for the existence of cooperativity (experimental evidences have already reported in our earlier work: Biochem. Biophys. Res. Commun., 293 (2002) 870) in the phenomenon of DNA renaturation has been obtained using a generalized birth-death master equation approach. Results have shown that no special searching mechanism (i.e. a facilitated mechanism) was necessary for complementary DNA strands to find their correct-contacts but searching by a 'random jump' method was enough to explain not only the observed cooperativity phenomenon but also the magnitude of correct-contact-forming rate constant. Impact of cooperativity phenomenon on length of primers and their specificity in polymerase chain reaction has also been discussed.

Grafting of glycidyl methacrylate (GMA) upon coralline hydroxyapatite in conjugation with demineralized bone matrix (CHA-DBM) using equal molar ratio of potassium persulfate/sodium metabisulfite redox initiating system was investigated in aqueous medium. The optimum reaction condition was standardized by varying the concentrations of backbone, monomer, initiator, temperature and time. The results obtained imply that the percent grafting was found to increase initially and then decrease in most of the cases. The optimum temperature and time were found to be 50 δC and 180 min, respectively, to obtain higher grafting yield. Fourier transform infrared (FT-IR) spectroscopy and X-ray powder diffraction (XRD)method were employed for the proof of grafting. The FT-IR spectrum of grafted CHA-DBM showed epoxy groups at 905 and 853 cm−1 and ester carbonyl group at 1731 cm−1 of poly(glycidyl methacrylate) (PGMA) in addition to the characteristic absorptions of CHA-DBM, which provides evidence of the grafting. The XRD results clearly indicated that the crystallographic structure of the grafted CHA-DBM has not changed due to the grafting reaction. Further, no phase transformation was detected by the XRD analysis, which suggests that the PGMA is grafted only on the surface of CHA-DBM backbone. The grafted CHA-DBM will have better functionality because of their surface modification and hence they may be more useful in coupling of therapeutic agents through epoxy groups apart from being used as osteogenic material.

Graft polymerization of glycidylmethacrylate (GMA) onto coralline hydroxyapatite (CHA) was carried out using potassium persulfate (K 2 S 2 O 8 ) and sodium metabisulfite (Na 2 S 2 O 5 ) as initiators in aqueous medium. To optimize the reaction conditions for getting maximum grafting yield, the concentrations of backbone, monomer, initiator, temperature and time were varied. The percent grafting was found to increase initially and then gradually decrease with respect to reaction parameters. The results obtained imply that the optimum temperature and time was 60°C and 180 min, respectively, to obtain higher grafting yield. The grafting results have been discussed and a mechanism involved in the grafting of GMA onto CHA is described. The grafted materials were analyzed with Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) measurements. The results of FT-IR confirmed the presence of epoxy group on the grafted CHA. The XRD pattern showed that there was no secondary phase in the apatite lattice due to chemical modification.

Many molecular biology and genomics techniques (including C(0)t analysis, PCR, and HPLC) depend upon the renaturation of DNA in solution. Traditionally, the renaturation process has been treated as a second-order kinetics reaction with the concentration of the DNA as the order parameter. However, second-order kinetics only describes complementary strand recognition and not the intramolecular "zipping" of complementary strands once recognition has been established. And also we cannot use simply the DNA concentration as the order parameter. Here I present an improved model that takes both phenomena into account using "mol-bases" as the order parameter. The model was tested experimentally and found to provide a more accurate description of the observed data than previous DNA renaturation models based solely on second-order kinetics.

The reaction of triarylideneacetylacetones with hydrazine hydrate in acetic acid affords an excellent yield of (E)-s-trans-1-acetyl-5-aryl-3-styryl-2-pyrazolines via decinnamoylation. The structures of these compounds were elucidated using 1H, 13C and two-dimensional NMR techniques such as H,H-COSY, C,H-COSY, NOESY and HMBC. 15N NMR data for these compounds were also obtained and the results are discussed. Copyright © 1999 John Wiley & Sons, Ltd.

Aim and Backrgound: A simple, rapid, precise and isocratic RP‑HPLC (Reverse Phase High Performance Liquid Chromatography) method is aimed to develop for the simultaneous estimation of Olmesartan Medoxomil and Metoprolol Succinate in bulk drug and pharmaceutical dosage form. Materials and Methods: The quantification is carried out using YMC‑Pack CN (250 × 4.6 mm, 5.0 μm) column and the mobile phase comprises of 0.05% Trifluoro acetic acid (TFA) and Acetonitrile (ACN) (70:30 v/v). The flow rate is 1.0 ml/min. The eluent is monitored at 220 nm. The retention times of Olmesartan Medoxomil and Metoprolol Succinate are 7.9 min and 4.1 min respectively. The method is validated in terms of linearity, precision, accuracy, specificity, limit of detection and limit of quantitation. Results: Linearity and percentage recoveries of both Olmesartan Medoxomil and Metoprolol Succinate are in the range of 5‑35 μg/ml and 100 ± 2%, respectively. The stress testing of both the drugs individually and their mixture is carried out under acidic, alkaline, oxidation, photo‑stability and thermal degradation (dry heat and wet heat) conditions and its degradation products are well resolved from the analyte peaks. Conclusion: This method was successfully validated for accuracy, precision, and linearity. Key words: HPLC, Metoprolol Succinate, Olmesartan Medoxomil, stability indicating method.

We develop a generalized theoretical framework on the binding of transcription factor proteins (TFs) with specific sites on DNA that takes into account the interplay of various factors regarding overall electrostatic potential at the DNA–protein interface, occurrence of kinetic traps along the DNA sequence, presence of other roadblock protein molecules along DNA and crowded environment, conformational fluctuations in the DNA binding domains (DBDs) of TFs, and the conformational state of the DNA. Starting from a Smolochowski type theoretical framework on site-specific binding of TFs we logically build our model by adding the effects of these factors one by one. Our generalized two-step model suggests that the electrostatic attractive forces present inbetween the positively charged DBDs of TFs and the negatively charged phosphate backbone of DNA, along with the counteracting shielding effects of solvent ions, is the core factor that creates a fluidic type environment at the DNA–protein interface. This in turn facilitates various one-dimensional diffusion (1Dd) processes such as sliding, hopping and intersegmental transfers. These facilitating processes as well as flipping dynamics of conformational states of DBDs of TFs between stationary and mobile states can enhance the 1Dd coefficient on a par with three-dimensional diffusion (3Dd). The random coil conformation of DNA also plays critical roles in enhancing the site-specific association rate. The extent of enhancement over the 3Dd controlled rate seems to be directly proportional to the maximum possible 1Dd length. We show that the overall site-specific binding rate scales with the length of DNA in an asymptotic way. For relaxed DNA, the specific binding rate will be independent of the length of DNA as length increases towards infinity. For condensed DNA as in in vivo conditions, the specific binding rate depends on the length of DNA in a turnover way with a maximum. This maximum rate seems to scale with the maximum possible 1Dd length of TFs in a square root manner. Results suggest that 1Dd processes contribute much less to the enhancement of specific binding rate under in vivo conditions for condensed DNA. There exists a critical length of binding stretch of TFs beyond which the probability associated with the random occurrence of similar specific binding sites will be close to zero. TFs in natural systems from prokaryotes to eukaryotes seem to handle sequence-mediated kinetic traps via increasing the length of their recognition stretch or combinatorial binding. TFs overcome the hurdles of roadblocks via switching efficiently between sliding, hopping and intersegmental transfer modes. The site-specific binding rate as well as the maximum possible 1Dd length seem to be directly proportional to the square root of the probability (p R) of finding a nonspecific binding site to be free from dynamic roadblocks. Here p R seems to be a function of the number of nsbs available per DNA binding protein () inside the living cell. It seems that p R > 0.8 when > 10 which is true for the Escherichia coli cell system.

The title compound, C13H12N4O6, containing a di­nitro­phenyl ring substituted on the pyrazole ring, was obtained by a reaction of ethyl aceto­acetate (2,4-di­nitro­phenyl)­hydrazone with Vilsmeier reagent. The benzene and pyrazole rings are oriented at an angle of 35.49 (6)° with respect to each other. The packing of the mol­ecules is controlled by intermolecular C—H⋯O hydrogen bonds, in addition to van der Waals forces.

The reaction is not sensitive to the electronic and sterical effects of the substituents on the pyrazolyl rings and affords the products with excellent yields.Substrate (V) with the substituent bearing a methylthio-group is oxidized to yield the methylsulfonyl pyridine derivative (IVb).

We develop a theory to explain the origin of the static and dynamical memory effects in transcription-factor-mediated transcription activation. Our results suggest that the following inequality conditions should be satisfied to observe such memory effects: (a) τ(L)≫max(τ(R),τ(E)), (b) τ(LT)≫τ(T), and (c) τ(I)≥(τ(EL)+τ(TR)) where τ(L) is the average time required for the looping-mediated spatial interactions of enhancer-transcription-factor complex with the corresponding promoter--RNA-polymerase or eukaryotic RNA polymerase type II (PolII in eukaryotes) complex that is located L base pairs away from the cis-acting element, (τ(R),τ(E)) are respectively the search times required for the site-specific binding of the RNA polymerase and the transcription factor with the respective promoter and the cis-regulatory module, τ(LT) is the time associated with the relaxation of the looped-out segment of DNA that connects the cis-acting site and promoter, τ(T) is the time required to generate a complete transcript, τ(I) is the transcription initiation time, τ(EL) is the elongation time, and τ(TR) is the termination time. We have theoretically derived the expressions for the various searching, looping, and loop-relaxation time components. Using the experimentally determined values of various time components we further show that the dynamical memory effects cannot be experimentally observed whenever the segment of DNA that connects the cis-regulatory element with the promoter is not loaded with bulky histone bodies. Our analysis suggests that the presence of histone-mediated compaction of the connecting segment of DNA can result in higher values of looping and loop-relaxation times, which is the origin of the static memory in the transcription activation that is mediated by the memory gene loops in eukaryotes.

In this paper, we develop a theory on the mechanism of distal action of the transcription factors, which are bound at their respective cis-regulatory enhancer modules on the promoter-RNA polymerase II (PR) complexes to initiate the transcription event in eukaryotes. We consider both the looping and tracking modes of their distal communication and calculate the mean first passage time that is required for the distal interactions of the complex of enhancer and transcription factor with the PR via both these modes. We further investigate how this mean first passage time is dependent on the length of the DNA segment (L, base-pairs) that connects the cis-regulatory binding site and the respective promoter. When the radius of curvature of this connecting segment of DNA is R that was induced upon binding of the transcription factor at the cis-acting element and RNAPII at the promoter in cis-positions, our calculations indicate that the looping mode of distal action will dominate when L is such that L > 2?R and the tracking mode of distal action will be favored when L < 2?R. The time required for the distal action will be minimum when L = 2?R where the typical value of R for the binding of histones will beR ? 16 bps and L ? 102 bps. It seems that the free energy associated with the binding of the transcription factor with its cis-acting element and the distance of this cis-acting element from the corresponding promoter of the gene of interest is negatively correlated. Our results suggest that the looping and tracking modes of distal action are concurrently operating on the transcription activation and the physics that determines the timescales associated with the looping/tracking in the mechanism of action of these transcription factors on the initiation of the transcription event must put a selection pressure on the distribution of the distances of cis-regulatory modules from their respective promoters of the genes. The computational analysis of the upstream sequences of promoters of various genes in the human and mouse genomes for the presence of putative cisregulatory elements for a set of known transcription factors using the position weight matrices available with the JASPAR database indicates the presence of cis-acting elements with maximum probability at a distance of ?102 bps from the promoters which substantiates our theoretical predictions. � 2010 IOP Publishing Ltd.

We develop a theory that explains how the thermally driven conformational fluctuations in the DNA binding domains (DBDs) of the DNA binding proteins (DBPs) are effectively coupled to the one-dimensional searching dynamics of DBPs for their cognate sites on DNA. We show that the rate gammaopt, associated with the flipping of conformational states of DBDs beyond which the maximum search efficiency of DBPs is achieved, varies with the one-dimensional sliding length L as gammaopt proportional, L(-2) and with the number of roadblock protein molecules present on the same DNA m as gammaopt proportional, m2. The required free energy barrier ERTO associated with this flipping transition seems to be varying with L as ERTO proportional, variant ln L2. When the barrier height associated with the conformational flipping of DBDs is comparable with that of the thermal free energy, then the possible value of L under in vivo conditions seems to be Lor=70 bps.

C 24 H 21 N 3 O 3 cristallise dans Pna2 1 avec a = 11,313, b = 19,187 et c = 9,6363 A, Z = 4; affinement jusqu'a R = 0,060. La structure moleculaire est asymetrique et les atomes N ont approximativement des structures rhomboedriques. Le compose presente des proprietes optiques interessantes.