The Penn State Protein Ladder system for inexpensive protein molecular weight markers

We have created the Penn State Protein Ladder system to produce protein molecular weight markers easily and inexpensively (less than a penny a lane). The system includes plasmids which express 10, 15, 20, 30, 40, 50, 60, 80 and 100 kD proteins in E. coli. Each protein migrates appropriately on SDS-PAGE gels, is expressed at very high levels (10–50 mg per liter of culture), is easy to purify via histidine tags and can be detected directly on Western blots via engineered immunoglobulin binding domains. We have also constructed plasmids to express 150 and 250 kD proteins. For more efficient production, we have created two polycistronic expression vectors which coexpress the 10, 30, 50, 100 kD proteins or the 20, 40, 60, 80 kD proteins. 50 ml of culture is sufficient to produce 20,000 lanes of individual ladder protein or 3750 lanes of each set of coexpressed ladder proteins. These Penn State Protein Ladder expression plasmids also constitute useful reagents for teaching laboratories to demonstrate recombinant expression in E. coli and affinity protein purification, and to research laboratories desiring positive controls for recombinant protein expression and purification.

Disentangling the magnetic dimensionality of an alleged magnetically isolated cuprate spin-ladder CuHpCl system: a long-lasting issue

Ab initio computations reveal that the magnetic topology of CuHpCl is 3D calling into question the validity of being quoted as a spin-ladder system. The calculated magnetization enables discriminating between its gapped, gapless and polarized phases.

Конкуренция концентрационного сужения и полевого уширения темного резонанса в лестничной системе уровней атомов рубидия: особенности проявления в тонких спектроскопических ячейках

The effect of electromagnetically-induced transparency in the ladder system of 5S1/2-5P3/2-5D5/2 levels of Rb atoms is studied. The effect of spectral narrowing of the dark resonance (DR) is shown depending on the density of atomic vapor and the thickness L of the spectroscopic cell, which contains Rb atomic vapor. The thickness L varies from 390 nm to 4 mm, the atomic density N increased to ~ 10^16 cm^-3, and intense coupling and weak probe radiation were used. The maximum effect, namely the 22-fold spectral narrowing of DR, was achieved in a cell with a thickness of L = 4 mm. With decreasing of the thickness L, the effect of spectral narrowing becomes weaker: for example, at L = 2 μm, a 2.4-fold spectral narrowing of DR occurs. The spectral narrowing of DR was practically absent at L = 0.8 μm, and with a further decrease to L = 0.4 μm with increasing of atomic vapor density, spectral broadening of DR began to occur. In almost all cases, at moderate atomic densities and high intensities of the coupling radiation, ~ 100% DR contrast was achieved. The effect of spectral narrowing and broadening of DR is explained.