Drying characteristics and evolution of the pore space in alginate scaffold with embedded sub-millimeter voids

Alginate scaffold has potential use in the controlled release of drugs and as a three dimensional structure for the formation of tissue matrix. This article describes the changes in the alginate scaffold when the moisture was removed from the scaffold under vacuum. Here, some scaffolds have self-aligned gas bubbles with average diameter of 500 μm, introduced through fluidic arrangement, prior to the crosslinking of the aqueous alginate film. The crosslinked gel film was dried in a vacuum oven at a constant temperature. The image of the alginate film prior to crosslinking was acquired under digital microscope, and was compared with the images of the dried scaffolds from the scanning electron microscope. The voids retained their identity at the time of drying, while the diameter was reduced to half of the initial value. The thickness of the scaffold was reduced ten folds. The presence of voids enhanced the drying rate when the drying was conducted at higher temperature. The drying primarily occurred in the falling rate period. The constant rate period was approached at lower moisture content for thin scaffolds without voids indicating the presence of surface moisture for substantial period. This feature was not observed for the scaffolds with voids. For these scaffolds, the shrinkage was insignificant except for the initial phase of drying. Based on this information, the conclusions were drawn on how the de-saturation of the various parts of the scaffold was phased.     

Exploring Supramolecular Self‐Assembly of Tetraarylporphyrins by Halogen Bonding: Crystal Engineering with Diversely Functionalized Six‐Coordinate Tin(L)2–Porphyrin Tectons

This study targets the construction of porphyrin assemblies directed by halogen bonds, by utilizing a series of purposely synthesized Sn(axial ligand)₂–(5,10,15,20‐tetraarylporphyrin) [Sn(L)₂‐TArP] complexes as building units. The porphyrin moiety and the axial ligands in these compounds contain different combinations of complimentary molecular recognition functions. The former bears p‐iodophenyl, p‐bromophenyl, 4′‐pyridyl, or 3′‐pyridyl substituents at the meso positions of the porphyrin ring. The latter comprises either a carboxylate or hydroxy anchor for attachment to the porphyrin‐inserted tin ion and a pyridyl‐, benzotriazole‐, or halophenyl‐type aromatic residue as the potential binding site. The various complexes were structurally analyzed by single‐crystal X‐ray diffraction, accompanied by computational modeling evaluations. Halogen‐bonding interactions between the lateral aryl substituents of one unit of the porphyrin complex and the axial ligands of neighboring moieties was successfully expressed in several of the resulting samples. Their occurrence is affected by structural (for example, specific geometry of the six‐coordinate complexes) and electronic effects (for example, charge densities and electrostatic potentials). The shortest intermolecular I???N halogen‐bonding distance of 2.991 Å was observed between iodophenyl (porphyrin) and benzotriazole (axial ligand) moieties. Manifestation of halogen bonds in these relatively bulky compounds without further activation of the halophenyl donor groups by electron‐withdrawing substituents is particularly remarkable.     

Studies on Spiroheterocycles,Part III: Synthesis of Diazaspiroundecanetetraone Derivatives Containing Biologically Active Heterocycles

Barbituric acid 2 upon Michael addition with dibenzal acetones 1a–c afforded the corresponding diazaspiro derivatives 3a–c . The base-catalyzed condensation of 3a–c with various aromatic aldehydes produces diarylidine derivatives 4a–l . The diarylidene compounds 4a–l on condensation with hydrazine, phenyl hydrazine, hydroxylamine, urea, guanidine carbonate, and hydrazine hydrate with acetic acid afforded their respective in situ oxidized products 5, 6, 7, 8, 9 , and 10 . The structures of the compounds are ascertained from their analytical and spectral data. Some of the compounds are screened for their biological activities against E. coli, B. cirroflagellosus, A. niger, and C. albicans.     

Effect of large light-heavy neutrino mixing and natural type-II seesaw dominance to lepton flavor violation and neutrinoless double beta decay

The European Physical Journal C - We present the EpIC Monte Carlo event generator for exclusive processes based on generalised parton distributions. EpIC utilises the PARTONS framework, which...     

Superdeformed structures and low Ω parity doublet in Ne-S nuclei near neutron drip-line

The structures of Ne, Na, Mg, Al, Si, P and S nuclei near the neutron drip-line region are investigated in the frame-work of relativistic mean field theory and non-relativistic Skyrme Hartree-Fock formalism. The recently discovered nuclei ⁴⁰Mg and ⁴²Al, which are beyond the drip-line predicted by various mass formulae are located within these models. We find many largely deformed neutron-rich nuclei, whose structures are analyzed. From the structure anatomy, we find that at large deformation low orbits of opposite parities (e.g. $\frac{1} {2}^ +$ and $\frac{1} {2}^ -$ ) occur close to each other in energy.     

Assessment of ingestion dose due to radioactivity in selected food matrices and water near Vizag,India

Activity concentrations of ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs were measured in milk, egg, fruit and fish samples collected around a proposed site for setting up nuclear facilities, near Vishakhapatanam. The activity concentrations of the radionuclides ranged from 0.002 to 10.6, 0.002 to 2.8, 0.1 to 7.2, 3 to 110.8, 0.03 to 3 mBq g^?1 for ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs considering analysed food matrices. Natural uranium was measured in drinking water samples and the values were below 15 ppb. The average ingestion dose was 2.07 ± 2.01, 2.81 ± 4.38, 7.66 ± 8.24, 1.28 ± 0.84 and 0.04 ± 0.05 μSv year^?1 for ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs in milk, egg, fruit, fish and water. The ingestion dose received was the highest for milk, due to its high ingestion rate. It was observed that ²²⁶Ra is the largest contributor of measured radionuclides in this study for the different food matrices analysed due to its high dose conversion factor. The study was carried out as a part of baseline data generation for this region with which future changes in the radiological scenario can be compared.     

Studies on the Suzuki reaction on methyl 1-(2-bromoaryl)-5-oxo-3-aryl/heteroaryl-pyrrolidin-2-carboxylate derivatives: synthesis of N-aryl modified monocyclic γ-lactam derivatives in search for newer antibacterial agents

A large number of novel N-aryl modified monocyclic γ-lactam derivatives have been prepared via Pd(0) catalyzed heteroarylation in the N-aryl part of (±) cis and (±) trans γ-lactam carboxylate derivatives 3(a–f) and 6(a–f), respectively, with furan-2-boronic acid and thiophen-2-boronic acid. (±) cis Methyl 1-(2-bromoaryl)-5-oxo-3-aryl/heteroarylpyrrolidin-2-carboxylate derivatives 3(a–f), were prepared in good yields from 1(a–f) via hydrolysis, stereoselective decarboxylation, followed by esterification. Corresponding trans isomers 6(a–f) were prepared by the standard method already reported by us.     

Efficient resonance energy transfer from dye to Au@SnO2 core–shell nanoparticles

The present study reports the shell thickness dependence fluorescence resonance energy transfer between Rhodamine 6G dye and Au@SnO₂ core–shell nanoparticles. There is a pronounced effect on the PL quenching and shortening of the lifetime of the dye in presence of Au@SnO₂ core–shell nanoparticles. The calculated energy transfer efficiencies from dye to Au@SnO₂ are 64.4% and 78.3% for 1.5 nm and 2.5 nm thickness of shell, respectively. Considering the interactions of single acceptor and multiple donors, the calculated average distances (r_n) are 75.8 and 71.5 Å for 1.5 nm and 2.5 nm thick core–shell Au@SnO₂ nanoparticles, respectively.     

Late-Stage Halogenation of Peptides,Drugs and (Hetero)aromatic Compounds with a Nucleophilic Hydrazide Catalyst

Unlike its other halogen atom siblings, chlorination of a bioactive compound can change its physiological characteristics, improve its pharmacological profile, and function as a point of diversification through cross-coupling reactions. As a result, it has been a crucial strategy for drug discovery and development. However, functional groups such as amines, amides, hydroxy groups, or carboxylic acids trap the Cl⁺, severely limiting the reactivity and making direct chlorination far too difficult to be practical. Herein, we introduce a nucleophilic sulfonohydrazide catalyst for late-stage halogenation of peptides and drugs. This direct, mild and metal-free protocol shows high functional-group tolerance and is compatible with a range of structurally diverse peptides, drugs and aromatic compounds. Furthermore, DFT studies indicate that the reaction most likely proceeds via a cationic transition state. The gram-scale synthesis, high stability and efficiency of the catalyst provide a facile route for late-stage functionalization and intermediates for further derivatization.