WEAR OF DRY FRICTION PAIRS CONSISTING OF HIGH-CARBON CHROME-VANADIUM STEELS AND HARD ALLOYS

Journal of Applied Mechanics and Technical Physics - The wear resistance of DI37-VI and EK80-VI steel is studied using a friction testing device. A sample made of high-carbon chromium-vanadium...     

Electromagnetic Launcher with Massive Light-Plasma Initiator

Technical Physics - The results of experiments with an initiator of lithium and graphite, whose mass was 10% of the mass of the projectile, are presented. Similar initiators produce plasma with a...     

Effective Charge in LiNbO3 Films Fabricated by Radio-Frequency Magnetron Sputtering Method

Physics of the Solid State - Amorphous Li–Nb–O films were deposited onto Si substrates by radio-frequency magnetron sputtering method. The fabricated heterostructures demonstrated the...     

Broadband Acousto-Optic Modulation of Optical Radiation

Acoustical Physics - Abstract—For broadband modulation of the intensity of optical radiation, the tandem arrangement two acousto-optic (AO) Bragg cells are proposed in which acoustic waves...     

1D-Bromobismuthates of Dipyridinoalkane Derivatives

The following bromobismuthates of organic cations (dipyridinoalkane derivatives) are synthesized and characterized: (4-NH₂PyC₅)BiBr₅ (I), (2-MePyC₂)BiBr₅ (II), (2-NH₂PyC₁₀)BiBr₅ · 0.65H₂O (III), (2-NH₂PyC₁₀)₄H₅O₂(BiBr₆)₃ (IV), (2-NH₂PyС₆)₂KBi₂Br₁₁ (V), (2-NH₂PyC₆)H₃OBiBr₆ · 2.33H₂O (VI), and (2-NH₂PyC₆)₃(BiBr₆)₂ · CH₃CN (VII). Three compounds obtained (I–III) contain the zigzag 1D chain (BiBr₅) _n . A new type of 1D chains, (KBi₂Br₁₁) _n , is found in the structure of compound V. Pseudo-1D chains of BiBr₆^3? anions can be observed in the 3D structures of compounds IV, VI, and VII. The crystallographic data were deposited with the Cambridge Crystallographic Data Centre (CIF files CCDC 1569478 (I)–1569484 (VII), respectively).     

Thek-partitioning problem

Thek-partitioning problem is defined as follows: Given a set of items {I ₁,I ₂,...,I _n} where itemIj is of weightwj 0, find a partitionS ₁,S ₂,...,S _m of this set with ¦S _i ¦ =k such that the maximum weight of all subsetsS _i is minimal,k-partitioning is strongly related to the classical multiprocessor scheduling problem of minimizing the makespan on identical machines. This paper provides suitable tools for the construction of algorithms which solve exactly the problem. Several approximation algorithms are presented for this NP-hard problem. The worst-case behavior of the algorithms is analyzed. The best of these algorithms achieves a performance bound of 4/3.     

Synthesis,conductivity, and the crystal structure of a new stable metal, β″-(<Emphasis Type="Italic">DOEO</Emphasis>)<Subscript>2</Subscript>HSeO<Subscript>4</Subscript> · H<Subscript>2</Subscript>O

The stable metal β″-(DOEO)₂HSeO₄ · H₂O I) based on a new donor compound, 3,4-(1,4-dioxanediyl-2,3-dithio)-3′,4′-ethylenedioxo-2,5,2′,5′-tetrathiafulvalene] (DOEO), is synthesized and structurally characterized for the first time. The synthesis is performed by the electrocrystallization technique (direct current density j = 2 × 10^?6 A/cm²). The crystals are triclinic, and the unit cell parameters are as follows: a = 5.495(1) Å, b = 9.715(2) Å, c = 16.878(3) Å, α = 83.52(3)°, β = 82.54(3)°, γ = 73.51(3)°, Z = 1, and space group \(P\bar 1\). The salt has a layered structure. The DOEO^1/2+ radical cation layers are aligned parallel to the ab planes. The HS_eO ₄ ^? · H₂O solvated anions are located in channels along the a axis and are disordered over two positions near the center of symmetry (1/2 0 0) with a probability of 50%. The conductivity of the salt is equal to 300–400 Ω^?1 cm^?1 at room temperature and increases upon cooling to the boiling point of liquid helium (4.2 K) by a factor of 100–200 depending on the sample.     

Crystal structure of the new radical cation salt (<Emphasis Type="Italic">DOET</Emphasis>)<Subscript>4</Subscript>[Fe(CN)<Subscript>5</Subscript>NO]<Subscript>1.25</Subscript>(C<Subscript>6</Subscript>H<Subscript>5</Subscript>Cl)<Subscript>0.75</Subscript>

A new radical cation salt based on 4,5-(1,4-dioxanediyl-2,3-dithio)-4′,5′-ethylenedithiotetrathiafulvalene (DOET) with the photochromic anion [Fe(CN)₅NO]^2?, namely, (DOET)₄[Fe(CN)₅ NO]_1.25(C₆H₅Cl)_0.75, is synthesized. Single crystals of this salt are studied using X-ray diffraction [a = 10.398(2) Å, b = 11.168(2) Å, c = 18.499(4) Å, α = 103.14(3)°, β = 92.80(3)°, γ = 106.02(3)°, V = 1996.3(7) ų, space group \(P\bar 1\), and Z = 1]. In the structure, radical cation layers alternate with anion layers along the c axis. The centrosymmetric dimers are formed by DOET radical cations in the donor layer with packing of the β type. Like the vast majority of DOET-based salts, the new salt possesses semiconductor properties.     

Crystal structure of double vanadates Ca9 R(VO4)7. II. R = Tb, Dy, Ho, and Y

Crystal structures of the compounds Ca₉ R(VO₄)₇ (R = Tb (I), Dy (II), Ho (III), and Y (IV) have been studied by the method of the full-profile analysis. All the compounds are crystallized in the trigonal system (sp. gr. R 3 c, Z = 6) with the unit-cell parameters (I) a = 10.8592(1), c = 38.035(1), V = 3884.2(2) ų; (II) a = 10.8564(1), c = 38.009(1) Å, V = 3879.6(2) ų, (III) a = 10.8565(1) and c = 37.995(1) Å, V = 3878.3(2) ų, and (IV) a = 10.8588(1), c = 37.995(1) Å, V = 3879.9(2) ų. In structures I–IV, rare earth and calcium cations occupy three positions—M(1), M(2), and M(5). Rare earth cations occupy the R ³⁺ positions almost in the same way: 2.7–2.6(2) cations in the M(1) position; 2.7–2.3(2) cations in the M(2) position, and 0.6–1.0(1) cation in the M(5) position. At the same time, the occupancy of the M(5) position regularly increases with a decrease of the R ³⁺ radius.     

Gold nanoparticles enhance the anti-leukemia action of a 6-mercaptopurine chemotherapeutic agent

6-mercaptopurine and its riboside derivatives are some of the most widely utilized anti-leukemic and anti-inflammatory drugs. Their short biological half-life and severe side effects limit their use. A new delivery method for these drugs based on 4-5 nm gold nanoparticles can potentially resolve these issues. We have found substantial enhancement of the antiproliferative effect against K-562 leukemia cells of Au nanoparticles bearing 6-mercaptopurine-9-beta-d-ribofuranoside compared to the same drug in typically administered free form. The improvement was attributed to enhanced intracellular transport followed by the subsequent release in lysosomes. Enhanced activity and nanoparticle carriers will make possible the reduction of the overall concentration of the drug, renal clearance, and, thus, side effects. The nanoparticles with mercaptopurine also showed excellent stability over 1 year without loss of inhibitory activity.