From an Al4-Cluster to Al+ Complexes: Lessons on Metalloidal Clustering

Low-valent aluminium compounds are among the most reactive and widely researched main-group compounds. Since the isolation of [(AlCp*)4] in 1991 as the first stable, molecular AlI compound, a variety of highly reactive neutral or anionic low-valent aluminium complexes were developed. In particular, the strongly basic aluminyl anions allowed for nucleophilic activation of a large variety of small molecules and formation of elusive transition-metal complexes. By contrast, an accessible cationic, low-valent aluminium compound combining the nucleophilicity of low-valent compounds with the electrophilicity of aluminium is hitherto unknown. Here, we report the synthesis of [Al(AlCp*)3]+[Al(ORF)4]– (RF = C(CF3)3) via a simple metathesis route. Unexpectedly, the complex ion forms a dimer in the solid state and in concentrated solutions. Addition of Lewis bases results in monomerization and coordination to the unique formal Al+ atom giving [(L)xAl(AlCp*)3]+ salts with L = hexaphenylcarbodiphosporane (cdp; x = 1), tetramethylethylenediamine (tmeda; x = 1) and 4-dimethylamino-pyridine (dmap; x = 3). Depending on the donor strength of the ligand added, the Al+–AlCp* bonds in the [(L)xAl(AlCp*)3]+ cluster cations can be finely tuned between very strong (L = nothing) to very weak and approaching isolated [Al(L)3]+ ions (L = dmap). We anticipate our easily accessible low-valent aluminium cation salts to be the starting point for investigation and potential application of this unusual compound class. In particular, the ambiphilic reactivity of the cationic, low-valent compounds will be studied. Moreover, knowledge gained from the stabilization of the reported complex salts is expected to facilitate the isolation and application of novel cationic, low-valent Al complexes.

Aralia armata roots: Extraction, isolation and molluscicidal activity against golden apple snails, Pomacea canaliculata

Aralia armata is one of the common herb species in mountainous areas, especially in the northern mountainous areas of Vietnam, which has potential in pharmaceutical and agricultural industries. Herein, we report that an oleanolic acid saponin named pseudogisenoside RT1 methyl ester (A) was isolated from the roots of the species Aralia armata. The fractionated extracts of dichloromethane, ethyl acetate, water and compound A were investigated for their molluscicidal effects, specifically on Pomacea canaliculata. The tests showed that the extracts and compound A from A. armata roots had good activity against P. canaliculata snail. In particular, compound A had a Lethal concentration of 50 (LC50) value of 16.443 µg/mL.

NANOSIZED STRUCTURES IN PbTe MATRIX WITH CdSe IMPURITIES

В работе проведены электронно-микроскопические исследования полупроводниковых соединений на основе PbTe с примесями дисперсных фаз CdSe. Как показали результаты исследования, в исходном нелегированном соединении PbTe содержание атомов свинца составляет около 63,8 вес%, а содержание теллура составляет 36,2 вес%, т.е. соответствует стехиометрическому составу. Согласно изображениям электронного микроскопа, эти компоненты равномерно распределены по площади. Результаты исследования также показали, что образующиеся новые фазы имеют размеры зерен от 90 нм до 2 мкм. Полученные значения параметра решетки для соединения теллурида свинца и сингония хорошо согласуются с литературными данными. Структура образующихся фаз имеет такую же симметрию, как и исходное нелегированное соединение PbTe, гранецентрированную кубическую решетку с классом симметрии Fm3m. В молекулах новых образующихся фаз, в которых преобладают содержания элементов Cd и Se, обнаружено изменение сингонии кристаллической решетки. In this work, electron microscopic studies of semiconductor compounds based on PbTe with impurities of dispersed CdSe phases have been carried out. As shown by the research results, in the initial undoped PbTe compound, the content of lead atoms is about 63,8 wt.%, and the tellurium content was 36,2 wt.%, i.e. corresponded to the stoichiometric composition. According to the electron microscope images, these components are evenly distributed over the area. The results of the study also showed that the formed new phases had grain sizes from 90 nm to 2 pm. The obtained values of the lattice parameter for the lead telluride compound and crystal system are in good agreement with the literature data. The structure of the resulting phases has the same symmetry as the initial undoped PbTe compound, a face-centered cubic lattice with the Fm3m symmetry class. In the molecules of the newly formed phases, in which the abundances of the elements Cd and Se prevailed, a change in the crystal lattice syngony was found.

Electronic properties of TaAs2 topological semimetal investigated by transport and ARPES

We have performed electron transport and ARPES measurements on single crystals of transition metal dipnictide TaA$s_{2}$ cleaved along the ($\overline{2}$ 0 1) surface which has the lowest cleavage energy. A Fourier transform of the Shubnikov-de Haas oscillations shows four different peaks whose angular dependence was studied with respect to the angle between magnetic field and the [$\overline{2}$ 0 1] direction. The results indicate elliptical shape of the Fermi surface cross-sections. Additionally, a mobility spectrum analysis was carried out, which also reveals at least four types of carriers contributing to the conductance (two kinds of electrons and two kinds of holes). ARPES spectra were taken on freshly cleaved ($\overline{2}$ 0 1) surface and it was found that bulk states pockets at constant energy surface are elliptical, which confirms the magnetotransport angle dependent studies. First-principles calculations support the interpretation of the experimental results. The theoretical calculations better reproduce the ARPES data if the theoretical Fermi level is increased, which is due to a small n-doping of the samples. This shifts the Fermi level closer to the Dirac point, allowing investigating the physics of the Dirac and Weyl points, making this compound a platform for the investigation of the Dirac and Weyl points in three-dimensional materials.

The Hospitaller Background of the Teutonic Order

This article examines the foundation in 1190/1191 of a German field hospital outside the walls of Acre during its siege by the Christians studied against a background of Hospitaller affairs in Jerusalem before its loss in 1187. The article relies on contemporary texts rather than the myths which rapidly appeared, while documents issued by the papal chancery suggest misunderstandings of the situation in Syria. The field hospital was the creation of Germans arriving at Acre by sea and overland but its later development inside the walls was, at least partly, conditioned by the long-term mistrust and strife between Romance-speaking and Germanic parties in Jerusalem where the Germans established, at some distance from the main Hospitaller compound, a separate church and hospital dedicated to Santa Maria Alamannorum. In 1143 the pope adjudicated that the Germans were to be subject to the Hospital but were to be administered by Germans speaking German to those for whom they cared. By 1187 there were Hospitaller brethren and possessions in German lands but Santa Maria Alamannorum seems not to have had its own members or properties there. Those Germans at Acre in 1190/1191 would have known about their Jerusalem hospital but would not have sought an institutional link with it because that would have recognized Hospitaller claims to control them. In 1187 the Hospitaller Master and many brethren were killed and their Jerusalem headquarters was lost; no new Master was elected for some time and control passed to a succession of evidently disoriented senior officers. A new Master Garnier de Nablus reached Acre in June 1191 but by then the Hospitallers' rift with the Germans had hardened. and the Teutonic foundation in Acre successfully maintained its independence. How far the Hospitallers’ mismanagement of the situation eventually limited or impoverished their own order's future in German lands remains incalculable.

Influence of piezoelectricity, doping and magnetostatic field on Brillouin amplification in compound (AIIIBV and AIIBVI) semiconductors

A theoretical formulation followed by numerical analysis describing Brillouin amplification in compound (AIIIBV and AIIBVI) semiconductors is explored. The threshold condition for the onset of Brillouin amplification is determined. Well above the threshold intensity, the influence of piezoelectricity, doping concentration, and external magnetostatic field on the parameters characterizing Brillouin amplification viz. Brillouin amplification coefficient, transmitted intensity of Brillouin-scattered Stokes mode (BSSM), and Brillouin cell efficiency of the Brillouin cell isestimated. Numerical analysis is made for three different Brillouin cells consisting of [Formula: see text]-InSb, [Formula: see text]-GaAs, and [Formula: see text]-CdS, at 77[Formula: see text]K duly irradiated by a pulsed CO2 laser. Efforts are directed towards to determine appropriate values of doping concentration and magnetostatic field to enhance the parameters characterizing Brillouin amplification, at lower excitation intensity, and to establish the suitability of compound semiconductors as hosts for fabrication of efficient Brillouin amplifiers.

New Anti-Cancer Drug Compounds to Treat FLT-3 Mutated Leukemia

Around 30 % of the acute myeloid leukemia (AML) patient present a FLT3 mutations, that can be divided in 2 groups: punctual mutations represent 5 % and internal tandem duplicates represent around 25 % (FLT3-ITD). AML with FLT3-ITD mutations lead to significantly poor prognosis often requiring allogenic stem cell transplant. Different drugs are used to treat AML such as midostaurin, azacytidine, and daunorubicin. In this study, MOLM-13 cells (adult acute myeloid leukemia), expressing the FLT3-ITD mutation, were used to test different drugs to decrease their cell proliferation and increase their apoptosis level, compared to midostaurin (an inhibitor of FLT3), for 24 hours treatment. MOLM-13 cells were cultured in RPMI1640, in presence of 2, 10 and 25 % of fetal bovine serum (FBS). 25 % FBS was tested to be as close as possible with the level of serum present in the blood. Adipose stromal cells (ASC) were used as a reference control, in absence of serum. Compounds A (targeting the FLT3 pathway) was used at various concentrations (0.05 to 100 µM), over 24h of treatment, in combination or not with compound B (targeting the DNA). Compound A has a high affinity for IRAK4, downstream kinase of TLR pathway, and has the potential to block FLT3 pathway. TLR pathway activation in leukemia, through Myd88 and IRAK4, is involved in the pro-inflammation response but it is also inducing cell proliferation and cell survival. Compound B is an inhibitor of the poly (ADP-ribose) polymerase (PARP), which are enzymes that are involved in DNA transcription, cell cycle regulation and DNA repair. When ASC were treated with the compound A, the caspase 3/7 activity was not different from the control, but the number of cells was lower at 50 and 100 µM, indicating that the compound A was delaying the cell growth. The number of MOLM-13 cells decreased, in a dose response manner with the compound A (1 to 100 µM). The level of caspase 3/7 activity was elevated, in a dose response manner, which is consistent with the decreased number of cells. MOLM-13 cells resisted more to the anti-cancer effect of the compound A at 25 % FBS, indicating that it could work on patients. Midostaurin, from 0.05 to 100 µM, was reducing the number of cells and increasing the caspase 3/7 activity in the cells, in a dose response manner, at 2, 10 and 25 % FBS. However, data suggest that at the lowest doses, midostaurin was more efficient than compound A, but the compound A was more efficient at higher dose than midostaurin. Compound B alone, at 10 µM, was decreasing the number of MOLM-13 cells and increase the apoptotic level for the 2, 10 and 25 % FBS. A synergistic effect was demonstrated with compound B (10 µM) mixed with low concentration of the compound A (from 1 to 50 µM), at 25 % FBS. This latest result suggest that it will be possible to lower the posology of the compound A when it will be given to the patients, in combination with the compound B. In conclusion, the data showed the compound A and compound B decreased the level of proliferation and increased the level of apoptosis in MOLM-13 cells, cultured with 2 to 25 % of FBS fetal bovine serum, even if MOLM-13 cells were more resistant to the deleterious drugs effect at 25% FBS. Their combination had a synergic effect in increasing the caspase 3/7 activity and decreasing the cell proliferation. Further studies will be necessary to understand more the molecular mechanism affected by the compound A and/or B in the FLT-3 pathway. The compounds A and B demonstrate potential in treatment of AML expressing FLT-ITD. Disclosures Oliva: Emmaus Lifesciences, Inc.: Current Employment. Villanueva: Emmaus Lifesciences, Inc.: Current Employment. Ochiai: Emmaus Lifesciences, Inc.: Ended employment in the past 24 months. Niihara: Emmaus Lifesciences, Inc.: Current Employment.