Synthesis of bishomoinositols and an entry for construction of a substituted 3-oxabicyclo[3.3.1]nonane skeleton

1,3,3a,7a-Tetrahydro-2-benzofuran was used as key compound for the synthesis of various bishomoinositol derivatives. The diene was subjected to an epoxidation reaction for further functionalization of the diene unit. The bisepoxide obtained was submitted to a ring-opening reaction with acid in the presence of water. Various bishomoinositols were synthesized. However, when the reaction was carried out in the presence of acetic anhydride, a substituted 3-oxabicyclo[3.3.1]nonane skeleton was formed. The mechanism of the formation of the products is discussed.     

Three-dimensional microfiber devices that mimic physiological environments to probe cell mechanics and signaling

Many physiological systems are regulated by cells that alter their behavior in response to changes in their biochemical and mechanical environment. These cells experience this dynamic environment through an endogenous biomaterial matrix that transmits mechanical force and permits chemical exchange with the surrounding tissue. As a result, in vitro systems that mimic three-dimensional, in vivo cellular environments can enable experiments that reveal the nuanced interplay between biomechanics and physiology. Here we report the development of a minimal-profile, three-dimensional (MP3D) experimental microdevice that confines cells to a single focal plane, while allowing the precise application of mechanical displacement to cells and concomitant access to the cell membrane for perfusion with biochemical agonists. The MP3D device--an ordered microfiber scaffold erected on glass--provides a cellular environment that induces physiological cell morphologies. Small manipulations of the scaffold's microfibers allow attached cells to be mechanically probed. Due to the scaffold's minimal height profile, MP3D devices confine cells to a single focal plane, facilitating observation with conventional epifluorescent microscopy. When examining fibroblasts within MP3D devices, we observed robust cellular calcium responses to both a chemical stimulus as well as mechanical displacement of the cell membrane. The observed response differed significantly from previously reported, mechanically-induced calcium responses in the same cell type. Our findings demonstrate a key link between environment, cell morphology, mechanics, and intracellular signal transduction. We anticipate that this device will broadly impact research in fields including biomaterials, tissue engineering, and biophysics.     

Stress‐Induced Stabilization of Crystals in Shape Memory Natural Rubber

In contrast to all known shape memory polymers, the melting temperature of crystals in shape memory natural rubber (SMNR) can be greatly manipulated by the application of external mechanical stress. As shown previously, stress perpendicular to the prior programming direction decreases the melting temperature by up to 40 K. In this study, we investigated the influence of mechanical stress parallel to prior stretching direction during programming on the stability of the elongation‐stabilizing crystals. It was found that parallel stress stabilizes the crystals, which is indicated by linear increase of the trigger temperature by up to 17 K. The crystal melting temperature can be increased up to 126.5 °C under constrained conditions as shown by X‐ray diffraction measurements.     

CoTPP-catalyzed reaction of saturated bicyclic endoperoxides

Saturated bicyclic endoperoxides were exposed to CoTPP (Cobalt-meso-tetraphenylporphyrine) in chloroform, the peroxide bond was cleaved and a mixture of products arising from fragmentation and reduction obtained.     

Structure of a ring enlarged product from the base induced rearrangement of dibromomethylenebenzonorbornene

The base-catalyzed rearrangement reactions of 2-bromomethylenebenzonorbornene8 and 2,2-dibromomethylenebenzonorbornene9 were studied. Reaction of8 with potassiumtert-butoxide in THF gave only the enol ether11 whose formation is rationalized via a carbene-cycloalkyne mechanism. However, treatment of9 with phenyllithium in THF at –40°C gave the ringenlarged dibromide13 whose structure is reported herein. The ring-enlarged product13 is rationalized in terms of carbanionic rearrangement. Quantum mechanical calculations are consistent with these observations.     

Using enchanted features of Constancy Adding Space Extension (CASE) to reduce the dimension of evolver dynamics: Single Monomial Probabilistic Evolution Theory

From physics point of view, this paper focuses on evolver dynamics which is in fact somehow another interpretation of quantum dynamics’ Heisenberg picture combined with the Probabilistic Evolution Theory (PREVTH) quite recently developed in Group for Science and Methods of Computing (Demiralp’s group). Even though PREVTH has been based on conicality, during CMMSE 2017 a new point of view and a novel extension have been built for PREVTH, Single Monomial Probabilistic Evolution Theory has been made available by the second author. This work focuses on a one-degree-of-freedom quantum system whose potential may be come very steep (anharmonic symmetric exponential potential) for constructing, first, evolver dynamics equations, and then, single monomial PREVTH by using degree escalating procedure together with commutativity relation based addition to the single monomiality coefficient matrix. Both procedures introduce certain arbitrary parameters into the structure of that matrix by using Constancy Adding Space Extension. Parameters are determined to suppress the norm square of single monomiality coefficient matrix. A convergence analysis for this new PREVTH has also been presented.     

Transition structures, energetics, and nucleus-independent chemical shifts for 6pi electrocyclizations of dienylketenes to cyclohexadienones: a DFT study

6pi electrocyclizations of dienylketenes to 2,4-cyclohexadienones have been investigated at the (U)B3LYP/6-31G level and found to be a favored and exothermic process for most dienylketenes. As evidenced by calculations, dienylketene cyclizations proceed via a pseudopericyclic process. If the terminal double bond of dienylketenes is embedded into a benzenoid-type aryl moiety, the partial or complete loss of aromaticity, as indicated by NICS values, increases the activation barrier and makes the reaction less exothermic or even endothermic. The effect of aromaticity is slightly less pronounced for dienylketenes carrying five-membered heterocyclic aromatic substituents. Slightly distorted planar transition structures have been located for these types of cyclizations. Forming bond lengths in transition structures range from 1.950 to 2.339 A.     

On Some New Generalized Difference Sequence Spaces

Let (x) = A(x) , where A(x) denotes the number of square-full integers not exceeding x. In this paper, we prove that (x) = O , which improves the exponent 4/27 obtained by Y.-C. Cai [5].     

Low and high temperature bromination of exocyclic dienes: high temperature bromination. Part 16

The electrophilic addition of bromine to an exocyclic diene, 5,6-dimethylenebicyclo[2.2.1]hept-2-ene, in CCl₄ at 0°C led to the formation of non-rearranged (73%) and rearranged products (27%). However, high temperature bromination of the exocyclic diene at 77°C suppressed the formation of the rearranged products. Similarly, bromination of 9,10-dimethylenetricyclo[6.2.1.0^2,7]undeca-2,4,6-triene at −10°C gave only the exo-1,2-addition product. Bromination at +5°C resulted in the formation of a mixture consisting of exo-1,2- and 1,4-addition products in a ratio of (1:4). High temperature bromination at 77°C resulted in the formation of the endo-1,2-addition product. Furthermore, it has been shown that the 1,4-addition product converts smoothly to the 1,2-addition product. The formation mechanism of the products is discussed and supported by calculations.