Shrunken Structure Research Articles

Preservation of the heart in ancient Egyptian mummies: A computed tomography investigation with focus on the myocardium.

The ancient Egyptians considered the heart to be the most important organ. The belief that the heart remained in the body is widespread in the archeological and paleopathological literature. The purpose of this study was to perform an overview of the preserved intrathoracic structures and thoracic and abdominal cavity filling, and to determine the prevalence and computed tomography (CT) characteristics of the myocardium in the preserved hearts of ancient Egyptian mummies. Whole-body CT examinations of 45 ancient Egyptian mummies (23 mummies from the Ägyptisches Museum und Papyrussammlung, Berlin, Germany, and 22 mummies from the Museo Egizio, Turin, Italy) were systematically assessed for preserved intrathoracic soft tissues including various anatomical components of the heart (pericardium, interventricular septum, four chambers, myocardium, valves). Additionally, evidence of evisceration and cavity filling was documented. In cases with identifiable myocardium, quantitative (measurements of thickness and density) and qualitative (description of the structure) assessment of the myocardial tissue was carried out. Heart structure was identified in 28 mummies (62%). In 33 mummies, CT findings demonstrated evisceration, with subsequent cavity filling in all but one case. Preserved myocardium was identified in nine mummies (five male, four female) as a mostly homogeneous, shrunken structure. The posterior wall of the myocardium had a mean maximum thickness of 3.6 mm (range 1.4-6.6 mm) and a mean minimum thickness of 1.0 mm (range 0.5-1.7 mm). The mean Hounsfield units (HU) of the myocardium at the posterior wall was 61 (range, 185-305). There was a strong correlation between the HU of the posterior wall of the myocardium and the mean HU of the muscles at the dorsal humerus (R = 0.77; p = 0.02). In two cases, there were postmortem changes in the myocardium, most probably due to insect infestation. To our knowledge, this is the first study to investigate the myocardium systematically on CT scans of ancient Egyptian mummies. Strong correlations between the densities of the myocardium and skeletal muscle indicated similar postmortem changes of the respective musculature during the mummification process within individual mummies. The distinct postmortem shrinking of the myocardium and the collapse of the left ventriclular cavity in several cases did not allow for paleopathological diagnoses such as myocardial scarring.

A self-gating proton-coupled electron transfer reduction of hexavalent chromium by core-shell SBA-Dithiocarbamate chitosan composite

We have proposed a novel strategy for the reduction plus adsorption process for hexavalent chromium elimination by thiol functional hybrid materials through a self-gating process. Namely, we exploit that coating dithiocarbamate chitosan at the surface of SBA-15 affords a core-shell composite that undergoes reversible shape transformations while thiol functional groups acted as proton-coupled electron donor for [Cr2O7]2−. The reduction of [Cr2O7]2− to Cr3+ was highly efficient and exceptionally rapid, occurred within 5 min with the reduction amount of 899.66 mg of [Cr2O7]2− / 1 g of nanocomposite as a record high value. During the reduction of [Cr2O7]2−, thiol functional groups (-SH) were oxidized into disulfide linkages (SS), and simultaneously chitosan matrix turned into shrunken structure because of the consuming of protons, preventing any release of Cr3+. Disulfides can also be reversely reduced to thiols by thiosulphates (S2O32−), which was attractive for regeneration and recyclability of the nanocomposite. Moreover, the [Cr2O7]2− elimination through self-gating process was highly selective against a huge concentration of background electrolytes. This alternative strategy ensures the outstanding and stable performance in applied fields, and could be conducted in various pollution control techniques like permeable reactive barriers.

Multi-responsive hydrogels with UCST- and LCST-induced shrinking and controlled release behaviors of rhodamine B

By using a disulfide-functionalized crosslinker, a pH- and thermo-responsive 2-(dimethylamino) ethyl methacrylate (DMAEMA) monomer and a zwitterionic sulfobetaine methacrylate (SBMA) monomer were conjugated to fabricate a multi-responsive P(DMAEMA-SS-SBMA) copolymeric hydrogel. Apparent UCST and LCST volume transitions were observed in the P(DMAEMA-SS-SBMA) hydrogels with equivalent weight fractions of monomers. Different pore size and response sensitivity of shrunken structures below UCST and above LCST were visualized by SEM images. The hydrogel exhibited a highly swollen state with a swelling ratio of 17.8 and a pore size of 106μm at 45°C, they deswelled unequally at 5°C with a compact surface with pore size of 30μm and a loose bulk with pore size of 83μm, while they deswelled uniformly at 65°C with dense shrunken structure with small pore size of 12μm. The dual-thermoresponsive hydrogel was promising in controlled drug release. The initial drug release was predominantly controlled by diffusion, and the long-term release was influenced by the swelling ratio. Below UCST, the relatively hydrophilic shrunken structure and slow diffusion had a synergistic effect on the sustained release. Above LCST, the fast diffusion and the rapid “off” effect of hydrophobic skin layer resulted in a burst release. Additionally, pH-tunable swelling and redox-sensitive degradation were also observed.

Chloride Selective Macrocyclic Bisurea Derivatives with 2,2'-Binaphthalene Moieties as Spacers.

A cyclic bisurea derivative 2a has been successfully prepared from the corresponding diamine and diisocyanate in the presence of tetrabutylammonium chloride as a template. A more soluble cyclic bisurea 2b has also been prepared by introduction of sterically bulky tert-butyl groups. X-ray crystal analyses of [2a·Cl]- and [2b·Cl]- revealed that overall structure was saddle like and the chloride anion was located in the center of the cavity. The bound chloride anion was hydrogen bonded by four N-H of urea groups and weakly hydrogen bonded by four 1-C-H of naphthyl groups, respectively. After removal of the bound chloride anions of [2b·Cl]- with silver nitrate, two different X-ray crystals of free 2b were obtained; one was intermolecular hydrogen bonded shrunken structure and the other was extended structure. Receptor 2b showed large binding ability for Cl-, however, the selectivity for Cl- against basic anions, such as AcO- and F-, has been insufficient. In aqueous MeCN, the association constant of 2b for Cl- was reduced but still large, and the selectivity for hydrophobic Cl- was greatly improved. In this solvent, 2b also selectively recognized alkaline metal chloride salts. Therefore, cyclic bisurea 2b is highly selective and effective Cl- selective receptor.

Remarkable Lattice Shrinkage in Highly Oriented Crystalline Three-Dimensional Metal-Organic Framework Thin Films.

Highly oriented crystalline thin films of metal-organic frameworks (MOFs) have promising practical applications, such as in gas separation, catalysis, and sensing. We report on the successful fabrication of highly oriented crystalline thin films of three-dimensional porous MOFs, Fe(pz)[M(CN)4] (M = Ni, Pd; pz = pyrazine). Synchrotron X-ray diffraction studies reveal not only the highly oriented crystalline nature but also the remarkable shrunken structure of the thin films (∼3-7% volume shrinkage) compared with bulk samples. Furthermore, because of lattice shrinkage, these films exhibit large lattice expansions upon guest adsorption, in marked contrast to the almost unchanged lattice in the bulk samples.

A Solvent-Driven Organogel Shrinkage

The observation of an organogel shrinkage induced by an external stimulus is reported. The solvent-driven shrinking process is accompanied by the formation of a skin layer, with the final shrunken structure exhibiting liquid crystalline order and parallelly aligned bamboo-like architecture.

Synthesis and characterization of grafted thermosensitive hydrogels for heating activated controlled release

Poly( N-isopropylacrylamide), PNIPAAm, hydrogels are negatively thermosensitive which means that they have an expanded hydrogel structure at low temperatures and a shrunken structure at high temperatures. Based on this negative thermosensitivity of PNIPAAm, a drug delivery system with PNIPAAm oligomers grafted onto poly(hydroxyethyl methacrylate) PHEMA, a thermally nonresponsive polymer was designed. Poly(hydroxyethyl methacrylate-g- N-isopropylacrylamide), P(HEMA-g-NIPAAm) hydrogels were synthesized to control the release of an imbedded drug. This new grafted system exhibited high diffusivity at temperatures greater than the lower critical solution temperature (LCST) of the PNIPAAm oligomers. Utilizing PNIPAAm's LCST of approximately 34 °C, the release rate was controlled by the temperature of the release medium. The LCST of PNIPAAm was tuned by making copolymers with hydrophobic butyl methacrylate (BMA). Theophylline and inulin release profiles were studied using PHEMA, PNIPAAm and P(HEMA-g-NIPAAm) at three temperatures with drug diffusion coefficients determined as a function of temperature and drug type. The molecular weights between crosslinks and mesh sizes of PHEMA hydrogels were calculated using Flory–Rehner and rubber-elasticity theories.

EFFECTS OF PH OF NA5P3O10/NAOH REACTION SOLUTION ON THE PROPERTIES OF CHITOSAN MICROSPHERES

With an attempt to expand the versatilities and applications in chitosan microspheres, chitosan were first converted into micro-droplets by using a high voltage electrostatic field system, and then treated with Na5P3O10/NaOH solution of volume ratio of 17/3, 19/1, 1/0 (pure Na5P3O10) or 0/1 (pure NaOH) to fabricate chitosan microsphere. By varying the pH values of these reacting agents, distinct morphological structures and properties of chitosan microspheres were further be changed. Chitosan microsphere prepared in this study exhibited a good spherical shape and was in a range of 185.8 ± 13.8 μm to 380.9 ± 11.5 μm in diameter. The size of chitosan microspheres varied by treating with various pH values of these reaction reagents. The prepared chitosan microspheres upon treatment with pH 7 of various ratios Na5P3O10/NaOH solution, all exhibited a shrunken surface morphological structure. This densely shrunken structure of microspheres yielded a stronger mechanical strength and a slower release rate of drug (5-FU), no matter what the ratios of Na5P3O10/NaOH solution was used. From the data of FTIR analyses, the protonated amino peak of NH3+ at around 1562 cm−1 has decreased significantly after treated with various pH values of these reaction reagents. It could be attributed to the linkage between phosphoric and ammonium ion of the protonated chitosan molecules. Besides, another boarder absorption at about 3366cm−1 of treated chitosan microspheres (under the employed range of pH values), which represented the hydrogen bonding was enhanced as compare with the pure chitosan material.