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Non-covalent interactions between of { N , N ′-bis[(2-pyridinyl)methylene]-1, 2-benzenediamine]-bis(nitrato)}Cu(II) with pyridoxine hydrochloride in methanol were investigated by a combination of physico-chemical and spectrophotometric methods at T = (298.15, 308.15 and 318.15) K under ambient pressure. From measured density and viscosity data the apparent molar volume ( ϕ V ), the slope ( S V ∗ ), standard partial molar volume ( ϕ V 0 ), standard transfer volume ( Δ t ϕ V 0 ), isobaric apparent molar expansibility ( ϕ E ), standard isobaric partial molar expansibility ( ϕ E 0 ), the viscosity B -coefficient, its temperature derivative (∂ B /∂ T ), solvation number ( S n ) were calculated and discussed on the basis of specific or non-specific (solute + cosolute) and (solute + solvent) interactions. Thermodynamics of viscous flow were discussed on the basis of the transition state theory. Spectrophotometric results indicated 1:1 (solute + cosolute) interaction between the complex and pyridoxine hydrochloride.

Limiting apparent molar volumes ( ϕ V 0 ) and viscosity B-coefficients of iron(III)-N, N′-ethylene-bis(salicylideneiminato)-chloride in binary mixtures of N, N-dimethylformamide (DMF) + acetonitrile (ACN) were determined from solution density and viscosity measurements at T = (298.15, 303.15, 308.15 and 313.15) K under ambient pressure. In the investigated temperature range, the relation: ϕ V 0 = a 0 + a 1 T + a 2 T 2 , was used to determine the temperature dependence of the ϕ V 0 values ( ∂ ϕ V 0 / ∂ T ) P , i.e., partial molar expansibilities ( ϕ E 0 ). The temperature dependence of partial molar expansibilities ( ϕ E 0 ), i.e., ( ∂ ϕ E 0 / ∂ T ) P and viscosity B-coefficients were used to reveal the nature and degree of (solute + solvent) and (solvent + solvent) interactions in the ternary solutions. The transition state theory was applied to analyze the viscosity B-coefficients on the basis of the activation parameters of viscous flow. The results indicated strong (solute + solvent) interactions between FeIII(salen)Cl and the solvent mixtures. FeIII(salen)Cl was found to be a structure promoter in the ternary solutions.

Zn(II) and Cd(II) complexes of a Schiff base derived from quinazoline-4(3H) one and 2-formylphenoxy acetic acid were prepared and characterized by elemental and different spectroscopic (IR, UV-Visible and NMR) analyses. The elemental analysis indicated the formation of the complexes: [ML(AcO)].H2O, where M stands for Zn(II) and Cd(II) and L stands for quinazoline-4(3H)-one Schiff base. The molar conductivities of the prepared complexes revealed their non-electrolytic nature. The complexes were also investigated for their antimicrobial activities by using turbidometric assay method.

In this study partial molar volumes (?V0) and viscosity B-coefficients of iron(III)-N, N'-ethylene-bis(salicylideneiminato)-chloride, abbreviated as FeIII(salen)Cl, in different aqueous methanol solutions were determined from solution density and viscosity measurements at temperatures 298.15, 303.15, and 313.15 K under ambient pressure. Apparent molar volumes (?V) and densities (?) were used to calculate the apparent molar expansibilities (?E), the partial molar expansibilities (?E0) and the temperature dependence of the partial molar expansibilities (?E0) at constant pressure, (??E0/?T)P of FeIII(salen)Cl solutions to reveal the nature of different interactions in the ternary solutions. The transition state theory was applied to analyze the viscosity B-coefficients on the basis of the activation parameters of viscous flow. The overall results indicated strong solute-solvent interactions between FeIII(salen)Cl and the solvent molecules, preferentially with water molecules and that FeIII(salen)Cl acts as a net structure promoter in the ternary solutions. UV-VIS absorption spectra of the ternary solutions also stand in support of the results obtained.

The complexation reaction between salicylaldehyde thiosemicarbazone, abbreviated as STSC, with Cu2+ ion was studied in the binary mixtures of methanol + 1,4-dioxane binary by using UV-Visible spectrophotometric and conductometric methods at different temperatures. The formation constants (Kf) for the 1:1 complex, Cu2+-STSC, were calculated from computer fitting of the absorbance and molar conductance data against various mole ratios (cM:cL or cL:cM) in different binary solvent mixtures. A non-linear correlation was observed for the variation of logKf for the complex against the solvent compositions. Various thermodynamic parameters (?H, ?S and ?G) for the formation of Cu2+-STSC complex were also determined from the temperature dependence of the stability constants (Kf). The results showed that the complexation reaction is affected by the nature and composition of the mixed solvents.

Ion–ion and ion–solvent interactions for N,N/-ethylene-bis(salicylideneiminato)-diaquochromium(III) chloride, [Cr(salen)(H2O)2]Cl, dissolved in solutions of 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, [bdmim]BF4 (0.005 to 0.020 mol · dm−3) in methanol (MeOH) were investigated by a combination of physicochemical properties at 298.15, 308.15 and 318.15 K under ambient pressure. From measured solution densities and viscosities apparent molar volume (φV), the slope ( S V ∗ ), standard partial molar volume ( φ V 0 ), transfer volume ( Δ t φ V 0 ), the viscosity B-coefficient, its temperature derivative (∂B/∂T), solvation number (Sn), etc. were calculated and discussed on the basis of ion–ion and ion–solvent interactions. In the investigated temperature range, the relation: φ V 0 = a 0 + a 1 T , was used to determine the temperature dependence of the partial molar volumes φ V 0 , i.e., partial molar expansibilities ( φ E 0 ). Temperature dependence of the viscosity B-coefficient (∂B/∂T) values revealed the complex to be a long-range structure breaker. Thermodynamics of viscous flow were discussed on the basis of the transition state theory.

Partial molar volumes ( ϕ V 0 ) and viscosity B-coefficients of salicylaldehyde anil zinc (II), abbreviated as SAZ, in (0.00, 0.02, 0.04 and 0.05) mol ⋅ dm−3 tetrabutylammonium bromide (Bu4NBr) solutions in methanol (MeOH) were determined from solution density and viscosity measurements at (298.15, 308.15 and 318.15) K under ambient pressure. Apparent molar volumes (ϕV) and solution densities (ρ) were further used to determine isobaric apparent molar expansibilities (ϕE), isobaric partial molar expansibilities ( ϕ E 0 ) and temperature dependence of isobaric partial molar expansibilities ( ϕ E 0 ) at constant pressure, ( ∂ ϕ E 0 / ∂ T ) P of SAZ solutions to study the nature of different interactions in the ternary solutions. The transition state theory was applied to analyze the viscosity B-coefficients of the ternary solutions on the basis of the activation parameters of viscous flow. The overall results indicated strong solute–solvent interactions between SAZ and the solvent mixture and SAZ acts as a net structure breaker in the ternary solutions. UV-Visible absorption spectra of the ternary solutions also stand in support of the results obtained.

The search for efficient synthetic procedures for natural products, drugs, and materials with economical and ecological advantages is an important area of current interst in synthetic organic chemistry. We have made an attempt to summarize the progress made in this area since 2005. This article describes the syntheses of several natural products and drugs that employ multiple palladium-catalyzed processes in either a sequential or a domino fashion. 1 Introduction 2 Palladium-Mediated Synthesis of Alkaloids 2.1 Indole Alkaloids 2.2 Carbazole Alkaloids 2.3 Quinoline and Isoquinoline Alkaloids 2.4 Pyrrole and Pyridine Alkaloids 2.5 Pyrrolizidine and Indolizidine Alkaloids 2.6 Imidazole and Guanidine Alkaloids 2.7 Other Alkaloids 3 Palladium-Mediated Synthesis of Natural Products Containing a Sugar Moiety 4 Palladium-Mediated Synthesis of Marine Natural Products 5 Palladium-Mediated Synthesis of Amino Acids and Peptides 6 Palladium-Mediated Synthesis of Terpenoids 7 Miscellaneous Natural Products 8 Conclusion

In this study we investigated the effects of tetrabutylammonium hydrogen sulphate (Bu4NHSO4) on the solute-solute and solute-solvent interactions in the aqueous solutions of nicotinic acid in terms of apparent molar volumes (?V), standard partial molar volumes (?V0) and viscosity B-coefficients at 298.15, 308.15, and 318.15 K under ambient pressure. These interactions are further discussed in terms of ion-dipolar, hydrophobic- hydrophobic, hydrophilic-hydrophobic group interactions. The activation parameters of viscous flow for Bu4NHSO4 in the aqueous solutions of nicotinic acid were discussed in terms of transition state theory. The overall results indicated that ion-hydrophilic and hydrophilic-hydrophilic group interactions are predominant in the aqueous solutions of nicotinic acid and Bu4NHSO4 has a dehydration effect on the hydrated nicotinic acid.

An efficient one-pot strategy for the synthesis of triazolobenzothiadiazepine 1,1-dioxide derivatives has been developed by the reaction of 2-azido- N -substituted benzenesulfonamides and propargyl bromide in basic alumina under microwave condition via [3+2] azide–alkyne cycloaddition reaction. This protocol has synthetic advantages in terms of low environmental impact and short reaction time.

Densities, viscosities and ultrasonic speeds of sound for binary mixtures of 1,2-dimethoxyethane (DME) with benzene, toluene, chlorobenzene, benzyl chloride, benzaldehyde, nitrobenzene, and aniline are reported over the entire composition range at ambient pressure and temperature (i.e., T=298.15 K and p=1.01×105 Pa). These experimental data were utilized to derive the excess molar volumes (\(V_{\mathrm{m}}^{\mathrm{E}}\)), excess viscosities (ηE), and various acoustic parameters including the deviation in isentropic compressibility (ΔκS), internal pressure (πI), and excess enthalpy (HE). From the excess molar volumes (\(V_{\mathrm{m}}^{\mathrm{E}}\)), the excess partial molar volumes (\(\overline{V}_{\mathrm{m},1}^{\mathrm{E}}\) and \(\overline{V}_{\mathrm{m},2}^{\mathrm{E}}\)) and excess partial molar volumes at infinite dilution (\(\overline{V}_{\mathrm{m},1}^{0,\mathrm{E}}\) and \(\overline{V}_{\mathrm{m},2}^{0,\mathrm{E}}\)) were derived and discussed for each liquid component in the mixtures. The excess/deviation properties were found to be either negative or positive, depending on the molecular interactions and the nature of the liquid mixtures.

An efficient synthesis of 3-iodopyrrolocoumarins has been achieved by a simple and straightforward strategy involving palladium–copper-catalyzed Sonogashira coupling followed by iodocyclization at ambient temperature using molecular iodine as the electrophilic source. In addition, functionalization at the 3-position of the iodocyclized product is performed via Sonogashira reaction.

Dispersions of zinc chromate (ZnCrO 4 ) were prepared in H 2 O/AOT (sodium bis(2-ethylhexyl sulfosuccinate))/n-heptane water-in-oil (W/O) microemulsion medium with various water pool sizes and precursor concentration both without and with sonication. The formation of ZnCrO 4 in the microemulsion was verified by XRD and FTIR measurements. The absorbance of the dispersions formed in different water pool sizes was studied. Their dimension in the microemulsion medium was determined by the dynamic light scattering method. Enthalpy of formation of ZnCrO 4 in W/O microemulsion medium was measured by isothermal titration calorimetry (ITC). The dimension and morphology of the formed ZnCrO 4 colloidal particles examined by transmission electron microscopy (TEM) were strongly dependent on the water pool size, precursor concentration and sonication.

Apparent molar volumes $${(\varphi_V)}$$ and viscosity B coefficients for L-alanine in (0.005, 0.010, 0.015, and 0.020) mol · dm−3 aqueous silver sulphate (Ag2SO4) solutions were determined from the solution density and viscosity measurements at (298.15, 308.15, and 318.15) K as a function of amino acid concentration. The standard partial molar volumes $${(\varphi_V^0)}$$ and experimental slopes $${(S_V^\ast )}$$ obtained from the Masson equation were interpreted in terms of solute–solvent and solute–solute interactions, respectively. To analyze solution viscosities in terms of viscosity B coefficients, the Jones–Dole equation was applied. The structure-making or -breaking ability of the amino acid has also been discussed in terms of the sign of $${(\delta^{2}\varphi_V^0/\delta T^{2})_{P}}$$ . The activation parameters of viscous flow for the ternary solutions were also derived and explained in terms of transition state theory.

Molar conductance of lithium acetate, sodium acetate and potassium acetate were studied in aqueous 2-butanol solutions with an alcohol mass fraction (w2) of 0.70, 0.80 and 0.90 at 298.15, 303.15 and 308.15 K. The conductance data were analyzed with the Fuoss conductance–concentration equation to evaluate the limiting molar conductances (Λ0), association constants (KA,c) and cosphere diameter (R) for ion-pair formation. Gibbs energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0) for ion-association reaction were derived from the temperature dependence of KA,c. Activation energy for ionic movement (ΔH#) was derived from the temperature dependence of Λ0. Based on the composition dependence of Walden products (Λ0η0) and different thermodynamic properties (ΔG0,ΔH0, ΔS0 and ΔH#), the influence of the solvent composition on ion-association and solvation behavior of ions were discussed in terms of ion–solvent, ion–ion interactions and the structural changes in the mixed solvent media.

Partial molar volumes ϕV0 and viscosity B-coefficients of N,N′-ethylene-bis(salicylideneiminato)cobalt(II), abbreviated as Co(salen), in different mass fractions (0 to 0.40) of 1,4-dioxane + methanol mixtures were determined from solution density and viscosity measurements at (298.15, 303.15, 308.15, and 313.15) K under ambient pressure. Apparent molar volumes ϕV and density data at the experimental temperatures were used to calculate the apparent molar expansibilities ϕE of Co(salen) solutions; the partial molar expansibilities ϕE0 were then determined from the relation: ϕE = ϕE0 + SE(m)1/2. The temperature dependence of ϕE0 values yielded (∂ϕE0/∂T)P; the signs of the (∂ϕE0/∂T)P values were discussed to reveal the structure promoting ability of Co(salen) in the experimental solvent/solvent mixtures. The activation parameters of viscous flow for the ternary solutions were also derived and discussed in terms of transition state theory. Various results indicated that the ternary system under investigation i...

A new synthetic protocol has been developed by the implementationof the palladium-mediated benzylic C-H activation followedby tethered intramolecular arylation strategy to give linearly fusedand unusually oxidized pyridocoumarin derivatives.

The excess molar volume (VE), viscosity deviation (Δη), deviation in isentropic compressibility (ΔKS), and excess molar refractivity (ΔR) have been investigated using experimentally measured densities, viscosities, speeds of sound, and refractive indices for the three binary mixtures 1,3-dioxolane (1) + diethyl ether (2), diethyl ether (1) + n-amyl alcohol (2), and 1,3-dioxolane (1) + n-amyl alcohol (2) and the corresponding ternary mixture 1,3-dioxolane (1) + diethyl ether (2) + n-amyl alcohol (3) at 298.15 K. The calculated quantities were further fitted to the Redlich−Kister equation to estimate the binary fitting parameters and standard deviations from the regression lines. The excess or deviation properties were found to be either negative or positive depending on the molecular interactions and the nature of the liquid mixtures.

A simple, efficient and cost effective method for a divergentsynthesis of benzoxepine derivatives using a hitherto unreported,highly regioselective, tandem iodocyclization procedure is described.

Densities, viscosities and ultrasonic speeds of sound were measured for the binary mixtures of cyclohexanone + 2-methoxy ethanol, + 2-ethoxy ethanol, + 2-butoxy ethanol, + diethylamine and + isopropylamine over the entire range of composition at 298.15 K. From the experimental density, viscosity and ultrasonic speed data, excess molar volumes ( ), viscosity deviations (Δη) and deviation in isentropic compressibility (ΔκS) have been calculated. The excess or deviation properties were fitted to Redlich–Kister polynomial equation. From excess molar volumes ( ), partial molar volumes ( and ) and excess partial molar volumes ( and ) at infinite dilution were calculated. Various acoustic parameters have also been calculated from the density and ultrasonic speed data. McAllister's three-body and Heric–Brewer model have been used to correlate viscosities of the binary mixtures. The various properties were discussed in terms of molecular and structural changes.

The synthesis of oxocines and oxepines is difficult. Two efficient protocols have been developed for the construction of naphthoxepine and naphthoxocine derivatives by sequential Wittig olefination and intramolecular Heck reaction.

This brief review article describes developments in the aza-Claisenrearrangement over the last nine years. In this article, the emphasishas been given to the various aspects of the aza-Claisen- rearrangement,especially metal-mediated stereoselective transformation, zwitterionicaza-Claisen rearrangement and microwave-assisted aza-Claisen rearrangement. 1 Introduction 2 Definition and Overview 3 Thermal Aza-Claisen Rearrangement 4 Catalysis of the Aza-Claisen Rearrangement 4.1 Catalysis by Boron Reagents 4.2 Catalysis by Palladium Reagents 4.3 Catalysis by Gold Salts 4.4 Catalysis by Ruthenium Salts 4.5 Catalysis by Zinc(II) Chloride 5 Zwitterionic Aza-Claisen Rearrangement 6 Microwave-Assisted Aza-Claisen Rearrangement 7 Miscellaneous 8 Conclusions

Electrical conductances of tetraalkylammonium iodides, R4NI (R = butyl to heptyl), in different mass % (20 to 80) of carbon tetrachloride (CCl4) + nitrobenzene (PhNO2) have been measured at 298.15 K. Limiting molar conductances Λ0, association constants KA, and cosphere diameter R for ion pair formation in the mixed solvent mixtures have been evaluated using the Lee−Wheaton conductivity equation. However, the deviation of the conductometric curves (Λ versus √c) from linearity for the electrolytes in 80 mass % of CCl4 + PhNO2 indicated triple ion formation, and therefore corresponding conductance data have been analyzed by the Fuoss−Kraus theory of triple ions. Limiting ionic molar conductances λ0± have been calculated by the reference electrolyte method along with a numerical evaluation of ion pair and triple ion formation constants (KP ≈ KAand KT); the results have been discussed in terms of solvent properties and configurational theory.

A new efficient protocol for the synthesis of benzannulated pyrido[2,3-d]- and pyrido[3,2-d]pyrimidines has been successfully accomplished via the palladium-catalyzed intramolecular arylation of C–H bond of pyrimidine moiety. The methodology has also been extended to the synthesis of pyrimido[5,4,-c]isoquinoline-2,4,6(1H,3H,5H)-trione derivatives in excellent yields.

The excess molar volumes, VmE, and viscosity deviations, Δη, were calculated from the measured density and viscosity data over the whole composition range for the ternary systems of cyclohexane (CHX) + cyclohexanone (CHXN) + methyl acetate (MA), ethyl acetate (EA), and propyl acetate (PA) and the constituent binary mixtures of cyclohexane or cyclohexanone + methyl acetate, ethyl acetate, propyl acetate, and cyclohexane or cyclohexanone at 298.15 K under atmospheric pressure. The excess or deviation properties of the binary and ternary systems were fitted to Redlich−Kister and Cibulka equations, respectively. The excess or deviation properties were found to be either negative or positive depending on the molecular interactions and the nature of liquid mixtures.

Uracil-annulated pyrano heterocycles are regioselectively synthesized in excellent yields (92–100%) via a palladium-catalyzed unusual [1,3] aryloxy shift followed by 6-endo dig cyclization and [1,3] prototropic shift.

The apparent molar volumes (Vϕ) and viscosity B-coefficients of sodium molybdate and sodium tungstate in aqueous binary mixtures of acetonitrile were determined from solution density and viscosity measurements at 298.15, 308.15 and 318.15 K and various electrolyte concentrations. The experimental density and viscosity data were evaluated by the Masson and Jones-Dole equations, respectively, and the parameters derived were interpreted in terms of ion-solvent and ion-ion interactions. The activation parameters of viscous flow were also determined and discussed using transition state theory.

Electrical conductances of tetraalkylammonium iodides, R4NI (R = pentyl to heptyl) have been measured at 298.15 K in low-permittivity mixtures of 1,4-dioxane (e = 2.21) and tetrahydrofuran (e = 7.58). Minima in the conductometric curves (Λ versus √c) were observed for electrolyte concentrations dependent upon both the electrolyte and the binary solvent mixture. The conductance data have been analyzed by the Fuoss−Kraus theory of triple ions. A numerical evaluation of ion-pair and triple-ion formation constants (KP and KT) was made, and the results have been discussed in terms of a molecular scale model.

Apparent molar volumes ϕV and viscosity B-coefficients for nicotinamide in (0.00, 0.05, 0.10, and 0.15) mol · dm−3 aqueous tetrabutylammonium bromide (TBAB) solutions have been determined from solution density and viscosity measurements at temperatures over the range (298.15 to 318.15) K as function of concentration of nicotinamide (NA). In the investigated temperature range, the relation: ϕ V ∘ = a 0 + a 1 T + a 2 T 2 , have been used to describe the temperature dependence of the standard partial molar volumes ϕ V ∘ . These results have, in conjunction with the results obtained in pure water, been used to deduce the standard volumes of transfer Δ ϕ V ∘ and viscosity B-coefficients of transfer for nicotinamide from water to aqueous TBAB solutions for rationalizing various interactions in the ternary solutions. The structure making or breaking ability of nicotinamide has been discussed in terms of the sign of ( δ 2 ϕ V ∘ / δ T 2 ) P . An increase in the transfer volume of nicotinamide with increasing TBAB concentration has been explained by Friedman–Krishnan co-sphere model. The activation parameters of viscous flow for the ternary solutions investigated were also determined and discussed by the application of transition state theory.

A concise and efficient method for the preparation of oxocine derivatives is described via sequential Wittig and intramolecular Heck reactions. The method is highly regioselective and affords high yields of the products.

Densities, viscosities and ultrasonic speeds were measured for the binary mixtures of 2-butanone (BU), + 2-methoxy ethanol (ME), + 2-ethoxy ethanol (EE), + 2-butoxy ethanol (BE), + isopropylamine (IPA), + cyclohexylamine (CHA) and + diethylamine (DEA) over the entire range of composition at 298.15 K. From the experimental values of density, viscosity and ultrasonic speed, excess molar volumes (VE), viscosity deviations (Δη) and deviations in isentropic compressibility (ΔKS) have been calculated. The excess or deviation properties were fitted to the Redlich–Kister polynomial equation to obtain their coefficients and standard deviations. To explore the nature of the interactions various thermodynamic parameters, e.g., intermolecular free length (Lf), specific acoustic impedance (Z) etc. have also been derived from the density and ultrasonic speed data. McAllister's multibody interaction model along with the Heric–Brewer model has been used to correlate kinematic viscosities (υ) of the binary mixtures. Also, the experimental values of density, viscosity and ultrasonic speeds of the mixtures at 298.15 K were fitted to a polynomial of the type: y = ∑ i = 0 3 a i x 1 i by the method of least-squares with each point weighed equally. The excess or deviation properties were found to be either negative or positive depending on the molecular interactions and the nature of liquid mixtures and have been discussed in terms of molecular interactions and structural changes.

Apparent molar volumes and viscosity B-coefficients of sodium molybdate in aqueous binary mixtures of 1,4-dioxane have been determined from density and viscosity measurements at 303.15, 313.15 and 323.15 K and at various electrolyte concentrations. Also, adiabatic compressibilities of different solutions have been determined from measurement of ultrasonic speeds of sound at 303.15 K. Experimental density data were evaluated using the Masson equation and the derived parameters interpreted in terms of ion–solvent and ion–ion interactions. Partial molar volumes ( ) and viscosity B-coefficients (ΔB) of transfer from water to aqueous 1,4-dioxane mixtures have also been calculated and discussed. The structure-making or breaking capacity of the electrolyte under investigation has been discussed in terms of the sign of .

Partial molar volumes (\(V_\phi^0\)) and viscosity B-coefficients of sodium molybdate in 1,3-dioxolane + water mixtures have been determined from solution density and viscosity measurements at 303.15, 313.15, and 323.15 K and at various electrolyte concentrations. Also, the adiabatic compressibility of different solutions has been determined from the measurement of sound speeds at 303.15 K. The experimental density data were evaluated by the Masson equation, and the derived parameters were interpreted in terms of ion–solvent and ion–ion interactions. The viscosity data have been analyzed using the Jones–Dole equation, and the derived parameters, B and A, have also been interpreted in terms of ion–solvent and ion–ion interactions, respectively. The structure- making or breaking capacity of the electrolyte under investigation has been discussed in terms of the sign of \((\delta ^{2}V_\phi^0/\delta T^{2})_{P}\) . The compressibility data obtained from sound speeds of different solutions indicate the electrostriction of the solvent molecules around the ions.

Apparent molar volumes and viscosity B-coefficients of glycine, l-alanine, and l-valine in 0.05, 0.10, and 0.15 mol·dm-3 aqueous tetramethylammonium iodide (TMAI) solutions have been determined at 298.15 K from density and viscosity measurements. The standard partial molar volumes, standard volumes of transfer, and hydration number of the amino acids have been calculated for rationalizing various interactions in the ternary solutions. It has been found that the partial molar volume and viscosity B-coefficient varies linearly with the number of carbon atoms in the alkyl chain of the amino acids, and they were split into contributions from charged end groups (NH3+, COO-) and the CH2− group of amino acids. Furthermore, the side chain contribution to the partial molar volume and viscosity B-coefficient of the amino acids has been determined using a group additivity approach. The results have been discussed in terms of ion−dipolar, hydrophobic−hydrophobic, and hydrophilic−hydrophobic group interactions.

Pure or aqueous alcohols are most widely used in industry, including in the manufacture of pharmaceuticals and cosmetic products. However, in the case of insolubility of some solutes in water, non-water solvents may be used possessing the common characteristic of being soluble in water; as a result, such solvents may be used with different purposes, such as increasing water solubility, or modifying the viscosity or absorption of the dissolved substance. Also, the nature of intermolecular forces between the solvents brings a marked effect on the thermodynamic properties such as density, viscosity and surface tension etc. The present study investigates viscous synergy and isentropic compressibility in the systems comprising some monoalkanols (C1–C4) and cyclic ethers (1,4-dioxane and tetrahydrofuran) in the proportion w/w = 1:1, in water at different concentrations (w/w) at 298.15 K to determine the proportion of monoalkanol + cyclic ether + water, at which maximum synergy occurs. The density and viscosity data have been analyzed using the equation developed by Kaletunc–Gencer and Peleg. Also a correlation between the density and viscosity increment for all the systems has been attempted. The ratio between maximum viscosity reached by the mixtures and pure state viscosity is expressed by the enhancement index defined as En = ηmax/η0.

Cold pressor test (CPT) is a well-known method for evaluating non-baroreflex mediated autonomic cardiovascular functions in humans. It has been reported that autonomic cardiovascular response to CPT differs in males and females and that heat stress attenuates the increase in arterial blood pressure during CPT. Study has also indicated that heat stress attenuates the increase in arterial blood pressure during CPT. The present study assessed the autonomic cardiovascular reactivity in males and females during cold pressor test before and after whole body heating for 40 min. 20 healthy Indian males and 18 females participated in the study. The participants were exposed to 40°C dry bulb temperature and 40% relative humidity in a simulated thermal chamber. They performed CPT before and after heat stress and their beat to beat heart rate and blood pressure were recorded. It was observed that baroreflex sensitivity (BRS) was significantly lower in females during CPT before heat stress (p0.01) as well as after heat stress (p0.01). Moreover, following whole body heating, the BRS during CPT increased slightly in females but not in males. Stroke Volume (SV) increased significantly during CPT before heat stress in females from pre-heat baseline (82 ml/beat vs. 101 ml/beat) (p0.001) as well as during CPT after heat stress from post-heat baseline (75 ml/beat vs. 95 ml/ beat) (p0.01). SV increased significantly in males during CPT after heat stress only (p0.01) as compared to post-heat baseline (82.5 ml/beat vs. 94.5 ml/beat). Frequency domain analysis of heart rate variability indicated that during CPT, low frequency power in males was higher than females (p0.05) and high frequency power was higher in females than males (p0.05). This suggests that autonomic modulation of cardiovascular function during CPT in males is mediated mainly via sympathetic neural system and in females it is mediated via vagal system. LF/HF ratio during CPT was found to be significantly higher in males (2.54) than females (1.27) before heat stress (p0.01).

Armed forces personnel including military aviators are quite often exposed concurrently to various environmental stressors like high environmental temperature and hypoxia. Literatures have suggested that exposure to one environmental stressor may modify the physiological response on subsequent exposure to same or different stressor. The present study was undertaken to investigate the impact of cross tolerance between two environmental stressors of aviation (heat and hypoxia) in ten healthy adult males in a simulated altitude chamber in a within subject experimental study. They were assessed for their convergence ability of the eyes at ground and at simulated altitude of 18,000 ft with or without pre-exposure to heat stress. Subjective convergence at simulated altitude of 18,000 ft did not show any improvement following pre-exposure to heat stress. Objective convergence was improved following pre-exposure to heat stress and was found to be 10.76 cm and 9.10 cm without and with heat stress respectively at simulated altitude of 18,000 ft. Improved objective convergence at high altitude as a result of pre-exposure to heat stress is indicative of better ocular functions. This might benefit aviators while flying at hypoxic condition.

Densities and viscosities were measured for the binary mixtures of 1,4-dioxane and 1,3-dioxolane with butyl acetate, butyric acid, butylamine, and 2-butanone at 298.15 K over the entire composition range. From density and viscosity data, the values of excess molar volume (V E) and viscosity deviation (Δη) have been determined. These results were fitted to Redlich−Kister type polynomial equations. The density and viscosity data have been analyzed in terms of some semiempirical viscosity models.

The excess molar volume (V E), viscosity deviations (Δη) and Gibbs excess energy of activation for viscous flow (G∗E) have been investigated from density (ρ) and viscosity (η) measurements of eight binary mixtures of 1,3-dioxolane with methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, and i-amyl alcohol over the entire range of mole fractions at 303.15 K. The viscosity data have been correlated with the Grunberg and Nissan equation. Furthermore, excess isentropic compressibilities (KSE) have been calculated from ultrasonic speed measurements of these binary mixtures at 303.15 K. The deviations have been fitted by a Redlich–Kister equation and the results are discussed in terms of molecular interactions and structural effects. The excess properties are found to be either negative or positive depending on the molecular interactions and the nature of the liquid mixtures. The systems studied exhibit very strong cross association through hydrogen bonding.

The densities, viscosities, and ultrasonic speeds of resorcinol in 1,4-dioxane + water mixtures and in pure 1,4-dioxane have been measured at 303.15, 313.15, and 323.15 K. Apparent molar volumes (Vϕ) and viscosity B-coefficients are obtained from these data supplemented with densities and viscosities, respectively. The limiting apparent molar volumes ( $$V_{\phi}^{0}$$ ) and experimental slopes ( $$S_{\rm v}^{\ast}$$ ) derived from the Masson equation have been interpreted in terms of solute–solvent and solute–solute interactions, respectively. The viscosity data have been analyzed using the Jones–Dole equation, and the derived parameters B and A have also been interpreted in terms of solute–solvent and solute–solute interactions, respectively. The structure making/breaking capacities of resorcinol in the studied solvent systems have been discussed. The compressibilities obtained from the data supplemented with their ultrasonic speeds indicate the electrostriction of the solvent molecules around the ions

Background The cold pressor test (CPT) is a recognized physiological technique to evaluate autonomic cardiovascular function. The present case study assessed the cardiovascular response of a healthy adult male during 3 min of CPT. Methods Heart rate (HR) by single-lead electrocardiography and blood pressure (BP) by an arterial tonometer of the participant on a beat-to-beat basis were recorded before and during CPT. Results HR during CPT showed a biphasic pattern with an initial increase from baseline (86 bpm) to the first 30 s of CPT (93 bpm) followed by a decrease. It dropped to 51 bpm during the last 30 s of CPT. Systolic blood pressure (SBP) increased from baseline (110 mmHg) to 1 min (122 mmHg) followed by a decrease. SBP immediately after CPT reduced to 57 mmHg. Diastolic blood pressure (DBP) from baseline (71 mmHg) slightly increased to 75 mmHg up to 90 s of the test, thereafter it registered a fall, and during the last 30 s of CPT, DBP fell to 30 mmHg. Stroke volume increased from baseline (75 mL/min) to the first 30 s (99 mL/min), followed by a slight reduction which was maintained till last of the test (70 mL/min). Cardiac output after an initial increase from baseline (6.4 L/min) to the first 30 s (9.2 L/min) decreased to 4.1 L/min during the last 30 s of the test. Baroreflex sensitivity (BRS) from baseline (9.32 ms/mmHg) plummeted to 6.67 ms/mmHg during the first 30 s of CPT followed by an increase, and after CPT, BRS was increased to 15.23 ms/mmHg. Other cardiovascular parameters such as myocardial contractility (dp/dt), total peripheral resistance, and mean arterial pressure were reduced in the individual at the time of loss of consciousness that occurred at the end of the last 30 s of CPT. Conclusions The present case study described the modulation of cardiovascular functions of a healthy male during CPT, which finally led to the development of neurocardiogenic syncope characterized by hypotension and bradycardia.

A simple and straightforward approach for the regioselective synthesis of pyranocoumarin and bis-fused benzo-2H-pyran derivatives using mild, easy to handle, and cheaper molecular iodine mediated heterocyclization is described.

Background: Surya Namaskar (SN), a popular traditional Indian yogic practice, includes practicing 12 physical postures with alternate forward and backward bending movement of the body along with deep breathing maneuvers. The practice of SN has become popular among yoga practitioners and other fitness conscious people. The long-term effect of practicing SN and other yogic practices on cardiorespiratory responses during SN are lacking. Aim: The present study was conducted to study the effect of yogic training on various cardiorespiratory responses during the SN practice in yoga trainees after a time interval of 3, 6, and 11 months. Materials and Methods: The present study was conducted on 9 healthy male Army soldiers who underwent training in various yoga postures including SN, meditation, and pranayama for 1 h daily for 11 months. First, second, and third phase of the study was conducted in the laboratory after completion of 3, 6, and 11 months of the yoga training. The participants performed SN along with other yogic practices in the laboratory as per their daily practice schedule. The cardiorespiratory responses of the volunteers were recorded during actual practice of SN. Statistical Analysis: One-way repeated measure ANOVA followed by Tukey HSD. Results: Oxygen consumption and heart rate during actual practice of SN was 0.794 ± 0.252, 0.738 ± 0.229, and 0.560 ± 0.165 L/min and 92.1 ± 11.6, 97.9 ± 7.3 and 87.4 ± 9.2 beats/min respectively at 1 st , 2 nd , and 3 rd phase of yoga training. Minute ventilation and tidal volume also reduced from 19.9 ± 4.65 to 17.8 ± 4.41 L/min and 1.091 ± 0.021 to 0.952 L/breath from 1 st phase to 3 rd phase of yoga training. However, respiratory parameters like breathing rate (f R ) did not show any reduction across the three phases. Conclusion: The results of the present study indicated that yogic training caused conditioning of cardiorespiratory parameters except f R, which did not reduce across three phases of training.

Surya Namaskar (SN), a popular traditional Indian yogic practice called "Sun Salutations", includes practice of twelve physical postures involving alternate backward bending and forward bending postures. The practice of twelve postures in succession makes one round of its practice. Many people practise it as part of their daily physical fitness regimen. No study is available to compare cardiorespiratory responses of SN with bicycle exercise (BE). 20 healthy Yoga instructors practicing various Yogic practices including SN since last 7-8 years participated in the study. They performed SN in the laboratory according to their customary daily practice routine. The subject also performed incremental load bicycle exercise test till exhaustion on their second visit for measuring their VO2 max. SN and BE were compared at three similar exercise intensity levels in terms of % of VO2 max. The exercise intensities were light (10-20% VO2 max), moderate (21-40% VO2 max) and high intensities (41-50% VO2 max). Heart rate at high work intensity was significantly higher in BE than SN (P.001). Ventilation and carbon dioxide output were significantly higher in BE than SN at high exercise intensity (P0.001). Overall, cardiorespiratory stress is less in SN than BE at similar work intensities.

Apparent molar volumes (φV) and viscosity B-coefficients for glycine in 0.005, 0.010, 0.015, and 0.020 mol dm-3 aqueous silver sulphate (Ag2SO4) solutions have been determined from solution density and viscosity measurements at (298.15, 308.15, and 318.15) K as a function of glycine concentration. The standard partial molar volume (φV0) and experimental slopes (SV*) obtained from the Masson equation have been interpreted in terms of solute-solvent and solute-solute interactions, respectively. The viscosity data were analyzed using the Jones-Dole equation, and the derived parameters A and B were interpreted in terms of solute-solute and solute-solvent interactions, respectively. The standard volumes of transfer (ΔφV0) and viscosity B-coefficients of transfer (ΔB) of glycine from water to aqueous Ag2SO4 solutions were derived to study various interactions in the ternary solutions. The structure making or breaking ability of glycine has been discussed in terms of the sign of (δ2φV0/δT2)P. The activation parameters of viscous flow for the ternary solutions were also calculated and explained in terms of transition state theory.