Ferro- and ferrielectricity and negative piezoelectricity in thioamide-based supramolecular organic discotics.

Amide-based discotic supramolecular organic materials are of interest for fundamental understanding of cooperative self-assembly and collective dipole switching mechanisms as well as for practically relevant ferroelectric and piezoelectric properties. Here, we show how replacing amides (dipole moment of ∼3.5 D) with thioamides (∼5.1 D) as dipolar moieties in the archetypal C3-symmetric discotic molecule BTA leads to ferroelectric materials with a higher remnant polarization and lower coercive field. The thioamide-based materials also demonstrate a rare negative piezoelectricity and a previously predicted, yet never experimentally observed, polarization reversal via asymmetric intermediate states, that is, ferrielectric switching.

Increased Extracellular Sodium Concentration as a Factor Regulating Gene Expression in Endothelium.

Hyperosmotic stimulation of endothelial cells often leads to its dysfunction accompanied, among other things, by proinflammatory response. The mechanisms of this phenomenon are not fully understood. It may arise due to increase in the plasma Na+ concentration, due to increase in the extracellular osmolarity, increase in the intracellular Na+i/K+i ratio, and/or change in the cell stiffness. In the present study we investigated the effects of short-term increase in osmolarity of extracellular medium on the mRNA content of some genes important for endothelial function (including Na+i/K+i-sensitive ones) and the equivalent elasticity constant of human umbilical vein endothelial cells membranes. Hyperosmotic stimulation of these cells with NaCl but not mannitol resulted in accumulation of Na+ ions inside the cells despite the Na,K-ATPase activation, and was also accompanied by the decrease in their equivalent elasticity constant. The amount of IL1α mRNA decreased with increasing osmolarity of the extracellular medium, whereas the amount of ATF3, PAR2, and PTGS2 mRNAs increased only in response to the increasing NaCl concentration. At the same time, under the conditions of our experiments, we did not detect changes in the expression of the osmoprotective transcription factor NFAT5. The obtained data indicate that the increase of extracellular Na+ concentration in the physiological range is an independent factor that affects intracellular Na+i/K+i ratio and regulates expression of some genes (in particular, ATF3, PAR2, PTGS2) in endothelial cells.

Mitigating effects of sublethal and lethal whole-body gamma irradiation in a mouse model with soluble melanin.

The field of radiation countermeasures is growing, however, currently there are no effective and non-toxic compounds which could be administered orally to the individuals post exposure to high doses of ionising radiation. The pigment melanin is ubiquitous through all kingdoms of life and provides selective advantage under radiation stress through its role as a chemical and physical shield, and its capacity to respond and react to exposures. Soluble allomelanin was administered to mice following whole-body exposure to lethal or sublethal doses of gamma radiation to determine its capacity to mitigate the effects of acute radiation syndrome, and its utility as a radiation countermeasure. Allomelanin has shown a trend to improve survival post an 8 Gy sublethal radiation exposure when administered up to 48 h post-irradiation. Furthermore, it improved median and overall survival to a 10 Gy lethal radiation exposure, specifically when administered at 24 h post-irradiation. Histological analysis on the jejunum region of the small intestine of this treatment group indicated that alterations of the mucosal and submucosal architecture, and disruption of the lymphatic system associated with lethal radiation exposure were mitigated when allomelanin was administered at 24 h post-irradiation. Based on this work soluble allomelanin derived from a fungal source could serve as an easily sourced, cost-effective, and viable countermeasure to accidental radiation exposure and merits further investigation.

Emergency Splenectomy in a Patient with Splenic Marginal Zone Lymphoma, Acute Portal Vein Thrombosis, and Chronic Viral Hepatitis B.

Splenic marginal zone lymphoma (SMZL) is a type of non-Hodgkin's lymphoma (NL) that occurs in 2 out of 100 cases and is more common in women aged >60 years. A sluggish, asymptomatic course of the disease does not exclude transformation into a malignant form that occurs in 25% of patients with SMZL. Another equally important sign of an NL is thrombosis that occurs in 3.6% to 17.1% of the cases. In this report, we present a case of emergency splenectomy in a patient owing to difficulties in the diagnosis of SMZL, rapid onset of acute portal vein thrombosis, and the fulminant enlargement of the spleen accompanied by an increased risk of its rupture. Chronic hepatitis B was likely the trigger for transformation of the disease to an aggressive course. Portal vein thrombosis and the aggressive course of SMZL with rapid enlargement of the spleen and threat of its rupture in the background of viral hepatitis B required emergency splenectomy followed by anticoagulant, antiviral, and antitumor therapy.

Microwave ablation of hepatic cyst: A case report.

Hepatic cystadenoma is an urgent problem due to the high risk of malignant transformation. There are both radical and minimally invasive methods of treatment. We present a clinical case describing the successful use of microwave ablation (MWA) in a 72-year-old woman with hepatic cystadenoma. The patient was admitted to the clinic with abdominal discomfort, dull pain in the right hypochondrium, and weight loss of 10 kg during the previous year. The patient had a past medical history of liver cyst in segment VII. Ultrasound scanning, computed tomography (CT) of abdominal organs detected an increase in the size of the cyst, heterogeneity of its structure; the contrast enhancement was noted in the cyst wall. We suspected hepatic cystadenoma in segment VII and performed cyst puncture under ultrasound control - the obtained fluid revealed the presence of cylindrical epithelial cells, mucin, and macrophages in large quantities, high telomerase activity, CA 19-9 levels were greater than 1000 U/mL. Surgery was accomplished using the MWA catheter. Biological and cytological examination of the fluid confirmed the presence of signs of liver cystadenoma with a high malignancy risk. On the 2nd day after surgery ultrasound imaging of the abdomen revealed the residual cavity of 2 × 1 cm in segment VII. The patient was discharged with recommendations to conduct ultrasound examinations every six months. The control CT scan in 2020 showed no focal or cystic formations in the liver. In what way, MWA under control of ultrasound is a promising method of biliary cystadenoma treatment with high malignancy risk.

Ferroelectric self-assembled molecular materials showing both rectifying and switchable conductivity.

Advanced molecular materials that combine two or more physical properties are typically constructed by combining different molecules, each being responsible for one of the properties required. Ideally, single molecules could take care of this combined functionality, provided they are self-assembled correctly and endowed with different functional subunits whose strong electronic coupling may lead to the emergence of unprecedented and exciting properties. We present a class of disc-like semiconducting organic molecules that are functionalized with strong dipolar side groups. Supramolecular organization of these materials provides long-range polar order that supports collective ferroelectric behavior of the side groups as well as charge transport through the stacked semiconducting cores. The ferroelectric polarization in these supramolecular polymers is found to couple to the charge transport and leads to a bulk conductivity that is both switchable and rectifying. An intuitive model is developed and found to quantitatively reproduce the experimental observations. In a larger perspective, these results highlight the possibility of modulating material properties using the large electric fields associated with ferroelectric polarization.

Ferroelectric switching and electrochemistry of pyrrole substituted trialkylbenzene-1,3,5-tricarboxamides.

We explore a new approach to organic ferroelectric diodes using a benzene-tricarboxamide (BTA) core connected with C10 alkyl chains to pyrrole groups, which can be polymerized to provide a semiconducting ferroelectric material. The compound possesses a columnar hexagonal liquid crystalline (LC) phase and exhibits ferroelectric switching. At low switching frequencies, an additional process occurs, which leads to a high hysteretic charge density of up to ∼1000 mC/m2. Based on its slow rate, the formation of gas bubbles, and the emergence of characteristic polypyrrole absorption bands in the UV-Vis-NIR, the additional process is identified as the oxidative polymerization of pyrrole groups, enabled by the presence of amide groups. Polymerization of the pyrrole groups, which is essential to obtain semiconductivity, is limited to thin layers at the electrodes, amounting to ∼17 nm after cycling for 21 h. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 673-683.

Switchable Charge Injection Barrier in an Organic Supramolecular Semiconductor.

We disclose a supramolecular material that combines semiconducting and dipolar functionalities. The material consists of a discotic semiconducting carbonyl-bridged triarylamine core, which is surrounded by three dipolar amide groups. In thin films, the material self-organizes in a hexagonal columnar fashion through π-stacking of the molecular core and hydrogen bonding between the amide groups. Alignment by an electrical field in a simple metal/semiconductor/metal geometry induces a polar order in the interface layers near the metal contacts that can be reversibly switched, while the bulk material remains nonpolarized. On suitably chosen electrodes, the presence of an interfacial polarization field leads to a modulation of the barrier for charge injection into the semiconductor. Consequently, a reversible switching is possible between a high-resistance, injection-limited off-state and a low-resistance, space-charge-limited on-state. The resulting memory diode shows switchable rectification with on/off ratios of up to two orders of magnitude. This demonstrated multifunctionality of a single material is a promising concept toward possible application in low-cost, large-area, nonvolatile organic memories.

A Versatile Method for the Preparation of Ferroelectric Supramolecular Materials via Radical End-Functionalization of Vinylidene Fluoride Oligomers.

A synthetic method for the end-functionalization of vinylidene fluoride oligomers (OVDF) via a radical reaction between terminal olefins and I-OVDF is described. The method shows a wide substrate scope and excellent conversions, and permits the preparation of different disc-shaped cores such as benzene-1,3,5-tricarboxamides (BTAs), perylenes bisimide (PBI), and phthalocyanines (Pc) bearing three to eight ferroelectric oligomers at their periphery. The formation, purity, OVDF conformation, and morphology of the final adducts has been assessed by a combination of techniques, such as NMR, size exclusion chromatography, differential scanning calorimetry, polarized optical microscopy, and atomic force microscopy. Finally, PBI-OVDF and Pc-OVDF materials show ferroelectric hysteresis behavior together with high remnant polarizations, with values as high as Pr ≈ 37 mC/m(2) for Pc-OVDF. This work demonstrates the potential of preparing a new set of ferroelectric materials simply by attaching OVDF oligomers to different small molecules. The use of carefully chosen small molecules paves the way to new functional materials in which ferroelectricity and electrical conductivity or light-harvesting properties coexist in a single compound.