Reversible binding interactions between the tryptophan enantiomers and albumins of different animal species as determined by novel high performance liquid chromatographic methods: an attempt to localize the D- and L-tryptophan binding sites on the human serum albumin polypeptide chain by using protein fragments

The stereoselectivity of the reversible binding interactions between the D- and L-tryptophan enantiomers and serum albumins of different animal species and fragments of human serum albumin (HSA) was investigated by applying three novel high performance liquid chromatographic (HPLC) arrangements. The separations were performed by means of (1) an achiral (diol-bond), (2) a chiral (bovine serum albumin-bond) silica gel sorbent, and (3) a column switching technique which uses both the diol- and HSA-bond HPLC stationary phases. A polarimetric detector and/or an ultraviolet (UV) spectrophotometer were used to monitor the separation process. HPLC arrangement 3 allowed the evaluation of enantioselective binding for D- and L-tryptophan to different albumins and albumin fragments. At present, column switching can be considered the technique of the broadest applicability for investigating the reversible binding interactions between a protein and drug enantiomers. Chirality 9:373–379, 1997. © 1997 Wiley-Liss, Inc.     

High‐resolution calorimetric and optical melting profiles of DNA plasmids: Resolving contributions from intrinsic melting domains and specifically designed inserts

We demonstrate that differential scanning calorimetry (DSC) can be used to yield high‐resolution melting profiles for DNA plasmids that agree in all major features with the corresponding plasmid melting profiles derived using more traditional optical techniques. We further demonstrate that by combining information derived from both calorimetric and optical melting profiles one can glean insights that are unavailable from either melting curve alone. By using both optical and calorimetric observables, we show how one can resolve, identify, and measure the thermodynamic properties of particular sequences/domains of interest within a plasmid. We also show that complementary DSC and optical melting studies on plasmids with and without specifically designed inserts can provide fundamental advantages over the corresponding melting studies on other model system constructs for thermodynamically characterizing nucleic acid sequences/structures. © 1999 John Wiley & Sons, Inc. Biopoly 50: 303–318, 1999     

An HPLC‐ESMS study on the solid‐phase assembly of C‐terminal proline peptides

DKP formation is a serious side reaction during the solid‐phase synthesis of peptide acids containing either Pro or Gly at the C‐terminus. This side reaction not only leads to a lower overall yield, but also to the presence in the reaction crude of several deletion peptides lacking the first amino acids. For the preparation of protected peptides using the Fmoc/tBu strategy, the use of a ClTrt‐Cl‐resin with a limited incorporation of the C‐terminal amino acid is the method of choice. The use of resins with higher loading levels leads to more impure peptide crudes. The use of HPLC‐ESMS is a useful method for analysing complex samples, such as those formed when C‐terminal Pro peptides are prepared by non‐optimized solid‐phase strategies. Copyright © 1999 European Peptide Society and John Wiley & Sons, Ltd.     

Exact Power of Conditional Tests for Several Binomial Populations

An efficient recursive polynomial multiplication method is proposed for exact unconditional power calculation for unordered 2 × K contingency table with up to moderate sample size. Our method can be applied to the family of cell-additive statistics which includes the Freeman-Halton statistic, the Pearson χ² statistic and the likelihood ratio statistic. We illustrate our proposed method by several numerical examples.     

Sub-0.6 eV Inverted Metamorphic GaInAs Cells Grown on Inp and GaAs Substrates for Thermophotovoltaics and Laser Power Conversion

Inverted metamorphic Ga_0.3In_0.7As photovoltaic converters with sub-0.60 eV bandgaps grown on InP and GaAs are presented. Threading dislocation densities are 1.3 ± 0.6 × 10⁶ and 8.9 ± 1.7 × 10⁶ cm⁻² on InP and GaAs, respectively. The devices generate open-circuit voltages of 0.386 and 0.383 V, respectively, under irradiance producing a short-circuit current density of ≈10 A cm⁻², yielding bandgap-voltage offsets of 0.20 and 0.21 V. Power and broadband reflectance measurements are used  to estimate thermophotovoltaic (TPV) efficiency. The InP-based cell is estimated to yield 1.09 W cm⁻² at 1100 °C versus 0.92 W cm⁻² for the GaAs-based cell, with efficiencies of 16.8 versus 9.2%. The efficiencies of both devices are limited by sub-bandgap absorption, with power weighted sub-bandgap reflectances of 81% and 58%, respectively, the majority of which is assumed to occur in the graded buffers. The 1100 °C TPV efficiencies are estimated to increase to 24.0% and 20.7% in structures with the graded buffer removed, if previously demonstrated reflectance is achieved. These devices also have application to laser power conversion in the 2.0–2.3 µm atmospheric window. Peak laser power converter efficiencies of 36.8% and 32.5% are estimated under 2.0 µm irradiances of 1.86 and 2.81 W cm⁻², respectively.     

A Safe Organic/Inorganic Composite Anode for Sodium-Ion Batteries

Sodium-ion batteries (SIBs), based on hard carbon anodes and Na⁺-intercalation compound cathodes, have gained significant attention. Nonetheless, hard carbon anodes involve the storage of Na⁺ at a low potential, typically below 0.1 V (vs Na/Na⁺), which increases the risk of dendritic Na growth on the anode surface during overcharging. Herein, a safe organic/inorganic composite anode containing tetrasodium 3,4,9,10-perylenetetracarboxylate (Na₄PTC) and Metallic bismuth (Bi) with a weight ratio of 7:2, which exhibits an average potential of 0.7 V (vs Na⁺/Na) and a capacity of 150 mAh g⁻¹ is proposed. The electrode reaction involves a reversible coordination reaction within the organic host and alloying reactions within the metallic Bi component. Importantly, the organic component efficiently buffers the volume changes in Bi during the alloying reaction, while the metallic Bi enhances the electronic conductivity of the organic material. As a result, this composite anode shows high cycle stability and rate performance, even under high mass loadings ranging from 10 to 50 mg cm⁻². Furthermore, it is demonstrated that the Na-ion full cell, consisting of the composite anode and the Na₃V₂O₂(PO₄)₂F cathode, exhibits minimal capacity degradation over 100 cycles while maintaining a high areal capacity of 1.1 mA cm⁻².     

Design of a high-power collimating optical system based on Fresnel lenses

In light-emitting diode (LED) illumination (e.g., LED maritime lighting for ships), creating a uniform light environment for optical systems is an important challenge. In this study, we present a high-power collimating system based on Fresnel lenses, which allows high-brightness LED illumination in the earlier-mentioned remote distance. The work presented in this article focuses on improving the power, compacting the optical structure, and promoting the brightness of the spot. To prove the claims, the system with a total power of 1 kW is designed. The system consists of a 27 W LED array, a freeform surface lens array, and a confocal Fresnel lens array. In comparison with the traditional optical system, the optical structure shortens from 390 to 120 mm, and the divergent angle decreases from 3° to 2 $$. Meanwhile, the illuminance of the system is obtained as high as 230 lx at the near field of 200 m and 3.0 lx at the far field of 1.5 nautical miles. This new method provides a practical and effective way to solve the problem of low power, insufficient illuminance, and long optical structure for LED array illumination, which is suitable for remote illumination and guidance of ships.     

Partial preferential chromosome pairing is genotype dependent in tetraploid rose

It has long been recognised that polyploid species do not always neatly fall into the categories of auto‐ or allopolyploid, leading to the term ‘segmental allopolyploid’ to describe everything in between. The meiotic behaviour of such intermediate species is not fully understood, nor is there consensus as to how to model their inheritance patterns. In this study we used a tetraploid cut rose (Rosa hybrida) population, genotyped using the 68K WagRhSNP array, to construct an ultra‐high‐density linkage map of all homologous chromosomes using methods previously developed for autotetraploids. Using the predicted bivalent configurations in this population we quantified differences in pairing behaviour among and along homologous chromosomes, leading us to correct our estimates of recombination frequency to account for this behaviour. This resulted in the re‐mapping of 25 695 SNP markers across all homologues of the seven rose chromosomes, tailored to the pairing behaviour of each chromosome in each parent. We confirmed the inferred differences in pairing behaviour among chromosomes by examining repulsion‐phase linkage estimates, which also carry information about preferential pairing and recombination. Currently, the closest sequenced relative to rose is Fragaria vesca. Aligning the integrated ultra‐dense rose map with the strawberry genome sequence provided a detailed picture of the synteny, confirming overall co‐linearity but also revealing new genomic rearrangements. Our results suggest that pairing affinities may vary along chromosome arms, which broadens our current understanding of segmental allopolyploidy.