The efficient regio- and stereoselective synthesis of (
,
)-3,3'-selanediylbis(2-propenamides) in 76-93% yields was developed based on the reaction of sodium selenide with ...3-trimethylsilyl-2-propynamides. (
,
)-3,3'-Selanediylbis(2-propenamides) are a novel class of organoselenium compounds. To date, not a single representative of 3,3'-selanediylbis(2-propenamides) has been described in the literature. Studying glutathione peroxidase-like properties by a model reaction showed that the activity of the obtained products significantly varies depending on the organic moieties in the amide group. Divinyl selenide, which contains two lipophilic cyclohexyl substituents in the amide group, exhibits very high glutathione peroxidase-like activity and this compound is considerably superior to other products in this respect.
The first Z-stereoselective method for the synthesis of the natural marine alkynol lembehyne C, containing a 1Z,5Z,9Z-triene moiety, in 41% yield was developed using the new Ti-catalyzed ...cross-coupling of oxygenated and aliphatic 1,2-dienes as the key step. It was found for the first time that lembehyne C exhibits moderate cytotoxicity against Jurkat, K562, U937, and HL60 cancer cells and also efficiently induces apoptosis in Jurkat cells, with the cell death mechanism being activated by the mitochondrial pathway. The lembehyne C inhibition of the cell cycle follows the mitotic catastrophe mechanism.
Schizophrenia is a chronic, complex and heterogeneous mental disorder, with pathological features of disrupted neuronal excitability and plasticity within limbic structures of the brain. These ...pathological features manifest behaviorally as positive symptoms (including hallucinations, delusions and thought disorder), negative symptoms (such as social withdrawal, apathy and emotional blunting) and other psychopathological symptoms (such as psychomotor retardation, lack of insight, poor attention and impulse control). Altered glutamate neurotransmission has for decades been linked to schizophrenia, but all commonly prescribed antipsychotics act on dopamine receptors. LY404039 is a selective agonist for metabotropic glutamate 2/3 (mGlu2/3) receptors and has shown antipsychotic potential in animal studies. With data from rodents, we provide new evidence that mGlu2/3 receptor agonists work by a distinct mechanism different from that of olanzapine. To clinically test this mechanism, an oral prodrug of LY404039 (LY2140023) was evaluated in schizophrenic patients with olanzapine as an active control in a randomized, three-armed, double-blind, placebo-controlled study. Treatment with LY2140023, like treatment with olanzapine, was safe and well-tolerated; treated patients showed statistically significant improvements in both positive and negative symptoms of schizophrenia compared to placebo (P < 0.001 at week 4). Notably, patients treated with LY2140023 did not differ from placebo-treated patients with respect to prolactin elevation, extrapyramidal symptoms or weight gain. These data suggest that mGlu2/3 receptor agonists have antipsychotic properties and may provide a new alternative for the treatment of schizophrenia.
The influence of cold rotary forging on the mechanical properties of the Cu/Al–10% La composite, depending on the billet’s reduction ratio, has been studied. The billet was forged from an original ...diameter of 20 mm to a final diameter of 2.5 mm (e = 4.16). It is shown that the formation of a predominantly subgrain structure with a high density of dislocations in a copper shell, and a predominantly ultrafine grain/subgrain structure in an aluminum rod provides an approximately two-fold increase in the strength of the composite material compared to its components. To clarify the mechanisms of deformation and fracture of the composite samples under tension, the acoustic emission technique was used. It is shown that by choosing the temperature of post-deformation annealing, it is possible to achieve the required balance between strength and plasticity of the composite samples. The electrical conductivity and coefficient of linear thermal expansion of the composite samples have been measured.
Abstract
Despite the progress made in the treatment of nephrolithiasis, the existing methods of renal calculi destruction are not ideal and have both advantages and disadvantages. Considering the ...process of high-frequency glow discharge formation on the surface of an electrode and in an electrolyte solution, we obtained the results on the destruction of renal calculi in vitro. It was shown that the destruction of kidney stones by glow discharge plasma was caused by several processes—the plasma induced effect of hydrated electrons and shock wave effect of the electrolyte stimulated by electrical breakdowns in the plasma. The plasma generation modes were configured by estimating the thickness of the vapor–gas layer in which the plasma burns. Thus, the average rate of contact destruction of renal calculi was measured depending on the plasma generator input power and time of plasma exposure. We conclude that the method of stone fragmentation by high-frequency electrolyte plasma is rather perspective and can be used in endoscopic urology for percutaneous and transurethral lithotripsy.
We present novel polyethylene (PE) composites for electromagnetic interference (EMI) shielding application. They are based on cobalt modified multi-walled carbon nanotubes (MWCNTs) produced via in ...situ polymerization of ethylene, with the Ti-Ziegler–Natta catalyst preliminarily immobilized on Co/MWCNT hybrids. The electromagnetic properties of the composites were tuned by varying the filler loading and Co:MWCNT ratio. The microstructure of the composites and electromagnetic absorption process were carefully characterized by transmission and scanning electron microscopy, X-ray diffraction, vibrating sample magnetometry, ferromagnetic resonance and vector network analysis. The electromagnetic wave absorbing properties of the nanocomposite were investigated in the 10 MHz−18 GHz frequency range revealing that the EMI absorption properties can be tuned by varying the Co:MWCNT weight ratio in the filler. Interestingly, the Co/MWCNT-PE composite with a total filler and Co loading of only 12 and 1.7 wt%, respectively, showed extremely high reflection loss (RL) of −55 dB. More importantly, an effective bandwidth of 12.8–17.8 GHz (RL below −10 dB) was achieved for a matching thickness of only 1.5 mm. The specific RL value (RL/filler loading) of the composite was superior in comparison with the previously reported nanostructured carbon materials. The highly effective absorbing properties of Co/MWCNT-PE composites are explained primarily by the unprecedented uniform filler distribution in the polyethylene as well as by the synergistic effect of MWCNTs and Co nanoparticles. This approach thus offered an effective strategy to design cost-effective, lightweight and flexible EMI shielding materials with tunable dielectric and magnetic performance.
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•New Co/MWCNT/polyethylene composites for EMI shielding applications were designed.•In situ polymerization ensured uniform distribution of Co/MWCNT filler in PE.•EMI shielding properties can be tuned by varying filler loading and Co:MWCNT ratio.•The effective bandwidth was 12.8–17.8 GHz at reflection loss below −10 dB.•Co/MWCNT/PE composite shows a minimum reflection loss value of −55 dB at 5.2 GHz.
In view of the probabilistic quantizer–dequantizer operators introduced, the qubit states (spin-1/2 particle states, two-level atom states) realizing the irreducible representation of the S U ( 2 ) ...symmetry group are identified with probability distributions (including the conditional ones) of classical-like dichotomic random variables. The dichotomic random variables are spin-1/2 particle projections m = ± 1 / 2 onto three perpendicular directions in the space. The invertible maps of qubit density operators onto fair probability distributions are constructed. In the suggested probability representation of quantum states, the Schrödinger and von Neumann equations for the state vectors and density operators are presented in explicit forms of the linear classical-like kinetic equations for the probability distributions of random variables. The star-product and quantizer–dequantizer formalisms are used to study the qubit properties; such formalisms are discussed for photon tomographic probability distribution and its correspondence to the Heisenberg–Weyl symmetry properties.
We have observed unusual plasma formations (UPFs) in artificial clouds of charged water droplets using a high‐speed infrared camera operating in conjunction with a high‐speed visible‐range camera. ...Inferred plasma parameters were close to those of long‐spark leaders observed in the same experiments, while the channel morphology was distinctly different from that of leaders, so that UPFs can be viewed as a new type of in‐cloud discharge. These formations can occur in the absence of spark leaders and appear to be manifestations of collective processes building, essentially from scratch, a complex hierarchical network of interacting channels at different stages of development (some of which are hot and live for milliseconds). We believe that the phenomenon should commonly occur in thunderclouds and might give insights on the missing link in the still poorly understood lightning initiation process.
Key Points
High‐speed infrared images allowed us to discover a new type of in‐cloud discharges
These discharges (UPFs) can occur both with and without spark
UPF morphology is distinctly different from that of leaders
First examples of the reactions of 3-trimethylsilyl-2-propynamides with organic diselenides yielding 3-alkylselanyl-2-propenamides and 3-organylselanyl-2-propynamides were realized. The latter ...compounds were obtained by the Cu-catalyzed reaction of organic diselenides with 4-propioloylmorpholine. The reaction of 3-trimethylsilyl-2-propynamides with dialkyl diselenides in the system NaBH4/H2O/K2CO3/THF proceeded in a regio- and stereoselective fashion, affording 3-alkylselanyl-2-propenamides in 90–94% yields. An unsymmetrical divinyl selenide with the cyclic amide groups and a product, containing two selanyl-2-propenamide moieties and three cyclic amide groups, were synthesized. The Cu-catalyzed allylation reaction of 3-trimethylsilyl-2-propynamides was accompanied with desilylation to yield 3-allyl-2-propynamides.
An efficient approach to a novel family of (Z)-3-amino-3-oxo-1-propenyl selenocyanates was developed based on the reaction of KSeCN with 3-trimethylsilyl-2-propynamides in the presence of ammonium ...chloride in methanol. The reaction was accompanied by a desilylation process. The products were not formed under the same reaction conditions in the absence of ammonium chloride, which was used for the first time in the reactions of selenocyanates with acetylenes. The use of this new methodology allowed the reaction to carry out in a regio- and stereoselective fashion as anti-addition affording vinyl selenocyanates with a (Z)-configuration in high yields.
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