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The polyphenol natural product curcumin possesses a plethora of biological and pharmacological properties. For years, much interest has been placed in the development and use of curcumin and its derivatives for the prevention and treatment of cardiovascular, diabetic, and neurodegenerative diseases, as well as cancer. Increasing evidence suggests that curcumin displays amazing molecular versatility, and the number of its proposed cellular targets grows as the research continues. The mammalian target of rapamycin ( mTOR) is a master kinase, regulating cell growth/proliferation, survival, and motility. Dysregulated mTOR signaling occurs frequently in cancer, and targeting mTOR signaling is a promising strategy for cancer therapy. Recent studies have identified mTOR as a novel target of curcumin. Here we focus on reviewing current knowledge regarding the effects of curcumin on mTOR signaling for better understanding the anticancer mechanism of curcumin. The emerging studies of mTOR signaling and clinical studies on curcumin with cancer patients are also discussed here.

We study the effect of comonomer sequence distributions in random copolymers (RCPs) on RCP adsorption on flat impenetrable surfaces. RCP poly(styrene-co-4-bromostyrene) (PBrxS), where x denotes the mole fraction of 4-bromostryrene (4-BrS), is prepared by bromination of parent homopolystyrene. By varying the solvent quality during the bromination, either “truly random” (good solvent) or “random-blocky” (poor solvent) PBrxS RCPs are prepared. Adsorption studies of PBrxS from various solvents at silica surfaces reveal that the adsorption of PBrxS increases with (1) increasing blockiness of the macromolecule, (2) increasing content of 4-BrS in PBrxS, and (3) decreasing solvent quality. Additionally, the effect of comonomer sequence distribution on RCP adsorption is modeled in detail using a coarse-grained statistical mechanical model and fully atomistic simulations based on configurational-biased grand-canonical Monte Carlo (CB-GCMC) technique. The main result from the simulations can be summarized as follows...

Curcumin (diferuloylmethane), a polyphenol natural product of the plant Curcuma longa, is undergoing early clinical trials as a novel anticancer agent. However, the anticancer mechanism of curcumin remains to be elucidated. Recently, we have shown that curcumin inhibits phosphorylation of p70 S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E (eIF4E) binding protein 1 (4E-BP1), two downstream effector molecules of the mammalian target of rapamycin complex 1 (mTORC1) in numerous cancer cell lines. This study was designed to elucidate the underlying mechanism. We observed that curcumin inhibited mTORC1 signaling not by inhibition of the upstream kinases, such as insulin-like growth factor 1 receptor (IGF-IR) and phosphoinositide-dependent kinase 1 (PDK1). Further, we found that curcumin inhibited mTORC1 signaling independently of protein phosphatase 2A (PP2A) or AMP-activated protein kinase AMPK-tuberous sclerosis complex (TSC). This is evidenced by the findings that curcumin was able to inhibit phosphorylation of S6K1 and 4E-BP1 in the cells pretreated with PP2A inhibitor (okadaic acid) or AMPK inhibitor (compound C), or in the cells expressing dominant-negative (dn) PP2A, shRNA to PP2A-A subunit, or dn-AMPKα. Curcumin did not alter the TSC1/2 interaction. Knockout of TSC2 did not affect curcumin inhibition of mTOR signaling. Finally, we identified that curcumin was able to dissociate raptor from mTOR, leading to inhibition of mTORC1 activity. Therefore, our data indicate that curcumin may represent a new class of mTOR inhibitor. [Cancer Res 2009;69(3):1000–8]

Inthis report, we present a simple methodology facilitating theformation of A-B random copolymers with tunable sequencedistributions. We demonstrate that varying the degree ofblockiness in the sequence distribution of A and B monomershas a profound impact on the partition of random copolymersat interfaces.Random copolymers (RCPs) are long chain moleculesmade of covalently bound monomers comprising at least twodifferent chemical moieties (say, A and B). In addition to theoverall molecular weight, RCPs are characterized by theircomposition and monomer sequence distribution. The abilityof A-B RCPs to act as “homopolymers with tunable composi-tion”, ranging between A and B homopolymers, has recentlyattracted considerable attention in controlling polymer misci-bility

Curcumin (diferuloylmethane), a polyphenol natural product of the plant Curcuma longa, is undergoing early clinical trials as a novel anticancer agent. However, the anticancer mechanism of curcumin remains to be elucidated. Here we show that curcumin inhibited growth of rhabdomyosarcoma cells (Rh1 and Rh30) (IC50 = 2–5 μM) and arrested cells in G1 phase of the cell cycle. Curcumin also induced apoptosis and inhibited the basal or type I insulin-like growth factor-induced motility of the cells. At physiological concentrations (˜2.5 μM), curcumin rapidly inhibited phosphorylation of the mammalian target of rapamycin (mTOR) and its downstream effector molecules, p70 S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E (eIF4E) binding protein 1 (4E-BP1), in a panel of cell lines (Rh1, Rh30, DU145, MCF-7 and Hela). Curcumin also inhibited phosphorylation of Akt in the cells, but only at high concentrations (>40 μM). The data suggest that curcumin may execute its anticancer activity primarily by blocking mTOR-mediated signaling pathways in the tumor cells. © 2006 Wiley-Liss, Inc.

Electro-optical Kerr-effect data have been obtained for various stereostructural forms of poly(N-vinyl carbazole) in solution in 1,4-dioxane over the temperature range 298–338 K. All of the polymers had a negative Kerr constant which become more positive with increasing temperature. Polymer samples with the largest isotactic content also had molar Kerr constants with the largest temperature coefficients.

The dielectric α-relaxation of a series of narrow-molecular-weight fractions of cyclic and linear polydimethysiloxanes (PDMSs) has been investigated as a function of frequency in the temperature range 140.5–157.5 K. The temperature of the α-transition decreases with increasing chain length for cyclic PDMS and increases with increasing chain length for linear PDMS, in agreement with the previously reported differential scanning calorimetry (d.s.c.) glass transition. The cooperativity of the relaxation process, according to the Kohlrausch-Williams-Watts analysis, is greater in linear PDMS. The activation energy and molecular dipole moment increase with increasing chain length for both cyclic and linear molecular types. Experimental values of the dipole moment ratio are in good agreement with those measured by static dielectric techniques and with the theoretical long-chain value.

The molecular dynamics of p-phenylene vinylene (PPV) oligomers, synthesised by a condensation reaction and separated by molecular distillation, have been investigated using the electrooptic Kerr effect. The experimental Kerr constants of these materials change sign from positive to negative in going from n = 1 to n = 2 and are not in good agreement with theoretical results. The discrepancies, which increase in magnitude as n increases, can be attributed to solvent-solute interactions, the nonplanar nature of PPV oligomers, or the nonvalidity of the additivity scheme chosen for calculation of theoretical quantities. © 1996 John Wiley & Sons, Inc.

The dipole moment has been measured for various stereostructural forms of poly( N -vinylcarbazole) (PVK) in solution in 1,4-dioxane and in toluene in the temperature range 288–338 K. The dielectric and dipole moment data were correlated with the stereostructure of PVK. The dipole moment behaviour of various types of PVK, prepared using different catalyst systems, may be explained in terms of 3/1, 2/1 or all- trans sequences of syndiotactic PVK. All PVK samples showed a positive temperature coefficient of dipole moment but to a different extent. PVK with lowest isotacticity (prepared with a free-radical catalyst) had the largest temperature coefficient, suggesting that this structure was more sensitive to changes in temperature. However, the dielectric data for cationically prepared PVK appear to indicate a more random coil-type of configuration or possibly a segmental, rod-like structure in which the dipole moment vectors of groups of carbazole groups are randomly oriented but remain approximately perpendicular to the long axis of the molecule, resulting in only a small temperature coefficient of dipole moment.

The α-relaxation of a linear poly(methylhydrogensiloxane) has been investigated as a function of temperature and frequency using dielectric relaxation spectroscopy. Replacement of the hydrogen with a hexyl group increased the temperature and broadness of the α-process, and this is interpreted in terms of a slowing of the motions of the Si—O dipoles and plasticisation of the siloxane chain by the side groups. Replacement of the hydrogen with a mesogenic group produced a side-chain liquid crystal which exhibited dielectric relaxation behaviour characteristic of the glass and liquid crystalline states.

Curcumin can induce p53-independent apoptosis. However, the underlying mechanism remains to be defined. Here, we show that curcumin-induced apoptosis in a panel of tumor cells with mutant p53. Curcumin rapidly induced activation of the mitogen-activated protein kinases (MAPKs) including extracellular signal-regulated kinase 1/2 (Erk1/2) and c-Jun N-terminal kinase (JNK). Inhibition of JNK (with SP600125) or Erk1/2 (with U0126) partially prevented curcumin-induced cell death in the cells. Similarly, expression of dominant negative c-Jun or downregulation of Erk1/2 in part attenuated curcumin-induced cell death. It appears that curcumin-induced activation of MAPKs and apoptosis was due to induction of reactive oxygen species (ROS), as pretreatment with N-acetyl-L-cysteine, a ROS scavenger, blocked these events. Furthermore, we found that curcumin-induced activation of MAPK pathways was related to inhibition of the serine/threonine protein phosphatases 2A (PP2A) and 5 (PP5). Overexpression of PP2A or PP5 partially prevented curcumin-induced activation of JNK and Erk1/2 phosphorylation as well as cell death. The results suggest that curcumin induction of ROS activates MAPKs, at least partially by inhibiting PP2A and PP5, thereby leading to p53-independent apoptosis in tumor cells.

A detailed analysis has been carried out of the proton magnetic resonance (PMR) splitting patterns of the methylene absorptions of β-chloroethyltrimethylsilane at 298 K. The effects of temperature on the PMR spectra of this compound have been examined. In addition, the PMR spectra of β-hydroxyethyltrimethylsilane, β-methoxyethyltrimethylsilane, and β-bromoethyltrisphenylsilane were obtained at a number of temperatures. A theoretical analysis of the PMR spectrum of β-chloroethyltrimethylsilane shows that the splitting patterns of the methylene absorptions may be satisfactorily represented by a hindered AA′XX′ system of protons. Commercial molecular modelling, software has been used to investigate the effects of van der Waals interactions on the conformations of some of these molecules. It is concluded from these various observations that there is severe steric hindrance about the C–C bond of the ethyl moiety in the β-halo systems. For the related β-hydroxy and -methoxy systems the results suggest that the rotation of substituents about the C–C bond is significantly less hindered. These conformational preferences could account for certain steric and kinetic effects observed in such systems.

119Sn Mossbauer spectroscopy has shown that attempts to intercalate three aryltin compounds (Ph3SnCl, (Ph3Sn)2O, Ph2SnCl2) into the synthetic smectite clay laponite under ambient conditions result in the formation of tin(IV) oxide pillared clays. The Mossbauer data indicate that the effectiveness of conversion to tin(IV) oxide pillars is in the order Ph3SnCl> (Ph3Sn)2O>Ph2SnCl2. The organic product of the pillaring reaction has been identified by13C m.a.s. n.m.r. spectroscopy as benzene trapped within the pillared clay. The pillaring in these new materials is achieved via neutral precursors rather than by sacrificial reaction of the exchanged cation. Measurements by A.C. conductivity measurements (12 Hz–100 kHz) show significant precursor related increases in conductivity for the new pillared materials as compared with sodium-exchanged laponite.

The intercalation of organotin-compounds into laponite and the formation of tin(IV) oxide pillars is rapidly achieved when performed in a microwave oven.119Sn Mossbauer- and x-ray- photoelectron-spectroscopy suggest that Ph3SnCl and Ph2SnCl2 undergo hydrolysis on the surface once sorbed. The treatment of Ph3SnCl/laponite with microwave radiation also induces the formation of a metallic phase which contains both tin and magnesium.

119 Sn Mossbauer spectroscopy studies have shown that attempts to intercalate three aryltin compounds [Ph 3 SnCl, (Ph 3 Sn) 2 O, Ph 2 SnCl 2 ] into the synthetic smectite clay laponite under ambient conditions result in the formation of tin(IV) oxide pillared clays. The Mossbauer data indicate that the effectiveness of conversion to tin oxide pillars is in the order: Ph 3 SnCl > (Ph 3 Sn) 2 O, Ph 2 SnCl 2 . The organic product of the pillaring reaction is benzene and has been identified by 13 C MASNMR spectroscopy as trapped in the pillared lattice. The new materials are novel since the pillaring was achieved via neutral precursors rather than by sacrificial reaction of the exchanged cation. The intercalation/pillaring reactions are much more rapid (5 min) when carried out in Teflon containers in a simple domestic microwave oven. Combined 119 Sn Mossbauer and X-ray photoelectron spectroscopic studies (XPS) suggest that, in the microwave experiments, Ph 3 SnCl has a higher initial affinity for the clay surface than (Ph 3 Sn) 2 O but that the chloride undergoes hydrolysis on the surface once sorbed. Evidence for the considerable mobility of Mg 2+ within the laponite lattice during microwave heating is presented.

The polyphenol natural product curcumin has been the subject of numerous studies over the past decades, which have identified and characterized the compound's pharmacokinetic, pharmacodynamic, and clinical pharmacological properties. In in vitro and in vivo model systems, curcumin displays potent pharmacological effects, by targeting many critical cellular factors, through a diverse array of mechanisms of action. Despite this tremendous molecular versatility, however, the clinical application of curcumin remains limited due to poor pharma- cokinetic characteristics in human beings. The current trend is to develop and utilize unique delivery systems, chemical derivatives, and chemical analogs to circumvent these pharmaco- logical obstacles, in order to optimize the conditions for curcumin as a chemopreventive and chemotherapeutic agent in diseases such as cancer, diabetes, obesity, Alzheimer's disease, and inflammatory disorders. The present work seeks to review recent studies in the basic pharma

A novel method has been developed for the rapid and simultaneous measurement of linear electric birefringence and linear electric dichroism of homogeneous, optically absorbing materials using pulsed electric fields. This method has been used to measure the linear electric birefringence and the linear electric dichroism, at a wavelength of 632.8 nm, of the copolymer poly(pentenylene-block-co-acetylene) in solution in cyclohexane at 298 K. The results are compared with those obtained using methods published by other authors.

The static dielectric permittivities, refractive indices and densities of undiluted oligomeric cyclic and linear dimethyl siloxanes and narrow fractions of cyclic and linear poly(dimethyl siloxanes) have been measured for number-average molar masses Mn in the range 160 M n at temperatures from 298 to 313 K. Measured total dielectric polarizations have been resolved into their electronic, atomic and orientation components and dipole moments have been derived. The dipole moments of cyclic oligomers ((CH3)2SiO)x (for example, with x = 4, 5) are markedly lower than the dipole moments of the corresponding linear oligomers containing the same number of siloxane bonds. However, for x ⩾ 10, the dipole moments of cyclic dimethyl siloxanes are identical, within experimental error, to those of the corresponding linear dimethyl siloxanes. Measured static dielectric permittivities of the dimethyl siloxanes and poly(dimethyl siloxanes) in solution in cyclohexane are markedly different from the corresponding values for the undiluted siloxanes. These differences are interpreted as resulting from the specific solvent effects.

The temperature dependence of optical rotation, static and dynamic Kerr-effect, and polarized and depolarized dynamic light-scattering for cholesteryl oleyl carbonate has been studied in a range including the isotropic liquid, homeotropic, and supercooled homeotropic states. Above the isotropic-cholesteric liquid crystal transition, marked pre-transitional effects are observed and are interpreted in terms of the build-up of angular correlations between molecules. On supercooling through this transition the observed magnitudes and correlation times are continuous well into the supercooled region, but show a smaller variation with temperature than that observed in the pre-transition range due, apparently, to a tendency for the angular correlation factors to saturate at the lowest temperatures. These data are discussed in relation to mean-field theory for mesogens and to the nature of the phase transformations between isotropic liquid, homeotropic liquid, and cholesteric focal-conic liquid crystal s...

The dielectric relaxation of Br(CH 2 ) N −1 Br, with N = 4 and N = 5, of Br(CH 2 ) N −1 Br with N = 3 and N = 4 and for 1,2-dichloroethane is deduced using the Jernigan method, where the internal conformational changes are governed by the rotational isomeric state model of Flory. It is found that the dipole moment correlation function for internal conformational changes depends upon the choice of reference coordinate system, and that the dipole moment correlation function cannot be generalized so as to include both overall and internal motions of the chain. An alternative approach, which involves the rotational isomeric state model but conserves angular momentum during an elementary conformational change, is suggested. The available microwave dielectric data on such compounds are considered in relation to the results of the theory.

The area of conducting polymers has been the subject of a great deal of discussion in the literature over the last 15 years. Polyacetylene is the material that has received the most attention during this period with strenuous efforts being made to produce a soluble copolymer containing polyacetylene segments. This paper is an overview of the synthetic techniques that have been used in order to try and produce these materials, which are both highly conducting and soluble in common organic solvents. Special emphasis has been placed upon the work which has led to the development of new catalyst systems and the work that has combined previously well characterized catalyst systems to produce novel materials.

Polyacetylene-block-polystyrene was synthesized via an anionic-to-metathesis catalysis. The polymers obtained were characterized by UV/visible spectroscopy, IR spectroscopy and gel permeation chromatography.

Rotational-isomeric-state models have been used to describe the statistical conformations of cyclic oligomers of dimethylsiloxane possessing 8–20 skeletal bonds. The results are compared with similar calculations made on linear-chain molecules of dimethylsiloxane. Cyclic dimethylsiloxanes, [(CH 3 ) 2 SiO] x , with x = 4–10, appear to be relatively rigid, compared with their linear-chain counterparts, and their average shape is disclike. For cyclic molecules possessing ≳ 50 skeletal bonds, the directional correlations between pairs of skeletal bonds approach those calculated for the corresponding open-chain molecules.

Dielectric relaxation times and electro-optical Kerr-effect relaxation times have been measured for melt samples of pure poly(propylene glycol) of nominal molecular weight 1025, 2025 and 4000, over the temperature range 209K–255K. Kerr-effect relaxation curves were analysed in terms of two main components: a ‘fast’ primary process (A), associated with a negative optical birefringence; and a ‘slow’ secondary process (B), associated with a positive optical birefringence. Measurement of dielectric loss at different frequencies for poly(propylene glycol) of molecular weight 2025 and 4000 indicated two main relaxation processes: a ‘fast’ process (the normal α-process), which carried with it most of the dielectric loss; and a ‘slow’ secondary process of much smaller amplitude. The close correspondence between dielectric and Kerr-effect relaxation times, for the primary and secondary relaxation processes, indicated that these techniques are probing effectively different aspects of the same molecular motion. Dielectric and Kerr-effect relaxation times for the secondary process depended greatly on the molecular weight of the polymer and were compared with the predictions of the models for the reptational motions of chains in the bulk polymer, as proposed by De Gennes and by Doi and Edwards.

Block copolymers containing polyacetylene and polypentenylene segments were synthesized by sequential addition of cyclopentene and acetylene to an active metathesis catalyst system. The ring-opening polymerization of cyclopentene was performed using WCl 6 AlEtCl 2 as catalyst. The polypentenylene chains produced were terminated by tungsten complexes, which formed the loci of acetylene monomer polymerization. By controlling the block length of the ‘solubilizing’ block, a range of materials that had differing solubilities was produced. The polypentenylene block length could be shortened by incorporating a linear alkene in the cyclopentene ring-opening polymerization step. Preliminary electro-optical measurements support the view that soluble polyacetylene copolymers exist as a polydisperse distribution of optically anisotropic aggregates.

Static and dynamic Kerr effect studies on poly(n-butyl isocyanate) (PBIC) and poly(n-octyl isocynate) (POIC) in CCl4 solution are reported and are compared with dielectric studies. The variation of dipole moment μ and Kerr constant factors θ1 and θ2 with temperature suggest the chains for MW ∼ 105 depart from a rod-like conformation, and this is also indicated by a detailed analysis of the dynamic Kerr effect and dielectric data. It is shown that the ratio of areas for the rise and decay transients for the Kerr effect are inconsistent with the simple model for rotational diffusion. In addition the averaging process involved in the apparent dielectric relaxation time 〈τD〉 and the Kerr effect decay average relaxation time 〈τK,d〉 is examined and it is shown that for rigid-rod, coil and Kratky-Porod behaviour that 〈τ D 〉 〈τ K,d 〉 ⋍ 〈 A D A K 〉 a factor which would be 3 for rotational diffusion, and is found to be ∼1 for PBIC and POIC again indicating the departure from simple rotational diffusion for the present samples.

Three different stereostructural forms of poly( N -vinyl carbazole) (PVK) have been prepared using cationic (AlCl 3 and BF 3 (CH 2 CH 3 ) 2 O) and radical (azobisisobutyronitrile) initiators. The dipole moment per repeat unit of PVK has been determined and correlated with 13 C n.m.r. spectra of the methine and methylene carbon absorptions for fractions of PVK in solution in 1,4-dioxan. The dielectric data for cationically prepared PVK appear to indicate a random coil configuration or possibly a rod-like structure in which the dipole moment vectors of the carbazole groups are randomly oriented but remain approximately perpendicular to the long axis of the molecule. For each type of PVK examined the repeat unit dipole moment was observed to be independent of molecular weight over the range 10 4 –10 7 and insensitive to polydispersity.

The statistical conformations of cyclic dimethylsiloxane oligomers [(CH3)2SiO]x with x in the range 4–10 have been studied by using rotational isomeric state models to describe the ‘cyclic’ conformations of the open chain molecules. Stringent criteria were used to select ‘cyclic’ conformations of the equivalent open chains based on the relative orientations and rotational states of their terminal skeletal bonds. The root-mean-square electric dipole moments 〈μ 2 〉 0 1 2 and the temperature coefficients d ln 〈μ 2 〉 0 dT were calculated using a modified form of the rotational isomeric state model of Flory, Crescenzi and Mark. The calculated dipole moments are compared with some experimental values measured for cyclic oligomers in the undiluted state at 298 K. For the ‘cyclic’ conformations of the open chains the magnitude of the calculated temperature coefficients for x = 5–9 were found to be very nearly inversely proportional to the fraction of rotatable skeletal bonds occupying trans rotational states; a functional dependence opposite to that found for the open chains.

The relationships between experimental quantities which arise due to the dynamics of molecules and the underlying time-correlation functions and time-dependent distribution functions are considered, with special emphasis being given to reorientational motions as detected by dielectric and closely related techniques. It is shown that pictorial representations of angular motion (small-step diffusion, free rotation, collision-interrupted rotation) may be given in terms of three and two dimensional diagrams of the time-dependent orientation distribution functions and that these afford a physical insight and appreciation of the averaged motions of ensembles of molecules.

The molecular Kerr constant has been measured for undiluted N-(p-Methoxybenzylidene)-p-n-butylaniline (MBBA) in the isotropic phase and also for MBBA in solution in benzene and carbon tetrachloride. The dependence of the molecular Kerr constant on concentration and temperature was studied. The anomalous optical properties manifested by pure MBBA in the isotropic phase were also found to be present in the solutions. De Gennes' theory was obeyed for undiluted MBBA and for concentrated solutions of MBBA in carbon tetrachloride. The infinite dilution molecular Kerr constant for MBBA in solution in benzene or carbon tetrachloride was readily interpreted in terms of modest anisotropies in the polarisability of the individual molecules.

The electro-optical Kerr effect has been measured for various stereostructural forms of poly( N -vinylcarbazole) (PVK) in solution in 1,4-dioxan at 298 K. The electro-optic behaviour of various types of PVK, prepared using different catalyst systems, may be explained in terms of 3 1 helical sequences of isotactic PVK and all- trans sequences of syndiotactic PVK. The Kerr effect of 2 1 and 4 1 helical forms of syndiotactic PVK has also been considered.

Dynamic Kerr-effect and dielectric relaxation studies have been for a poly(methylphenyl siloxane) fluid in the region of its α relaxation process. The relaxations are broader than a single relaxation-time process and we find τK,r < τK,d < τϵ and βK,r ≅ βK,d < βϵ, where K, r; K, d and ϵ refer to Kerr-effect rise, decay and dielectric, respectively; τ and β are the relaxation time and the Williams-Watts relaxation parameter, respectively. It is suggested that the observed Kerr-effect relaxation is largely due to the motions of the phenyl group and that a substantial part of this process is due to motions about the bond joining the silicon atom to the aromatic ring.

The little-used variable nutation angle method that permits the very rapid measurement of NMR spin-lattice relaxation times is reevaluated. The selection of the appropriate experimental conditions is discussed and the sensitivity of the deduced T1′s to these conditions is explored. To facilitate the more widespread use of this time-saving, yet accurate, method the experimental conditions and procedures are reported in some detail. The basic method is extended to provide an extremely rapid method for measuring T1. It is concluded that the driven-equilibrium single-pulse methods of measuring T1, yield values for T1 that are consistent with those obtained from the classical (180-τ-90) pulse sequence and have the advantage of being at least 100 times faster than the classical method.

Copolymers containing acetylene and pentenamer units were synthesized by sequential addition of cyclopentene and then acetylene to an active metathesis catalyst system. The formation of block copolymers was indicated by UV-vis spectroscopy, gel permeation chromatography and infra-red spectroscopy.

The electro-optical Kerr constants of equeous solutions of some naturally-occuring L-α-amino acids have been measured. The Kerr effect technique is well able to discriminate between solutions of different amino acids despite the relatively small differences between their dielectric constant increments. L-valine and L-isoleucine, whose structures are very similar, have Kerr constant increments of 3.6 and 2.28, respectively.

In studies of ring-chain competition, the polysiloxanes have probably been treated in greater detail than any other synthetic polymer system. They have also proved to be the most convenient source of cyclic material for investigations of the properties of cyclic polymers. Several factors combine to make the polysiloxanes eminently suitable for such purposes. High proportions of cyclic material are generated together with linear components of high molecular weight, so facilitating the separation of cyclic from linear material. While they are generally highly reactive in the presence of certain polymerization or equilibration catalysts, they have excellent thermal stability and adequate chemical stability to allow accurate and reliable analysis and experimentation. In this chapter, we describe the essential procedures which have been followed in preparing and analysing the products of cyclization reactions and in separating fractions of cyclic siloxane material.

Curcumin (diferuloylmethane), an orange-yellow component of turmeric or curry powder, is a polyphenol natural product isolated from the rhizome of the plant Curcuma longa. For centuries, curcumin has been used in some medicinal preparation or used as a food-coloring agent. In recent years, extensive in vitro and in vivo studies suggested curcumin has anticancer, antiviral, antiarthritic, anti-amyloid, antioxidant, and anti-inflammatory properties. The underlying mechanisms of these effects are diverse and appear to involve the regulation of various molecular targets, including transcription factors (such as nuclear factor-kB), growth factors (such as vascular endothelial cell growth factor), inflammatory cytokines (such as tumor necrosis factor, interleukin 1 and interleukin 6), protein kinases (such as mammalian target of rapamycin, mitogen-activated protein kinases, and Akt) and other enzymes (such as cyclooxygenase 2 and 5 lipoxygenase). Thus, due to its efficacy and regulation of multiple targets, as well as its safety for human use, curcumin has received considerable interest as a potential therapeutic agent for the prevention and/or treatment of various malignant diseases, arthritis, allergies, Alzheimer's disease, and other inflammatory illnesses. This review summarizes various in vitro and in vivo pharmacological aspects of curcumin as well as the underlying action mechanisms. The recently identified molecular targets and signaling pathways modulated by curcumin are also discussed here.