Enhanced Uniformity and Area Scaling in Carbon Nanotube–Fullerene Bulk‐Heterojunction Solar Cells Enabled by Solvent Additives

Single‐walled carbon nanotube (SWCNT) fullerene solar cells have recently attracted attention due to their low‐cost processing, high environmental stability, and near‐infrared absorption. While SWCNT–fullerene bulk‐heterojunction photovoltaics employing an inverted architecture and polychiral SWCNTs have achieved efficiencies exceeding 3% over device areas of ≈1 mm², large‐area SWCNT solar cells have not yet been demonstrated. In particular, with increasing device area, spatial inhomogeneities in the SWCNT film have limited overall device performance. Here, 1,8‐diiodooctane (DIO) is utilized as a solvent additive to reduce fullerene domain size and to improve SWCNT–fullerene bulk‐heterojunction morphology. Under optimized conditions, DIO elucidates the influence of SWCNT chiral distribution on overall device performance, revealing a tradeoff between short‐circuit current density and fill factor as a function of the chirality distribution present. The combination of SWCNT chirality distribution engineering and improved spatial homogeneity via solvent additives enables area‐scaling of SWCNT–fullerene solar cells with performance comparable to small‐area cells.     

Isolation and characterization of a distantly related member of the beta-gamma crystallin super gene family from Xenopus

In an attempt to isolate gamma crystallin genes from Xenopus genomic library, we have obtained seventeen clones which strongly hybridized to the gamma 1 cDNA probe from Rana temporaria. Of these four clones are characterized. A restriction map was derived by using single and multiple digests with a variety of enzymes. Hybridization selection of lens mRNAs and in vitro translation produced a protein of 26,000 daltons. These data suggest that the above clones may contain at least part of the gamma or beta crystallin sequences.     

Engineering of a wheat germ expression system to provide compatibility with a high throughput pET-based cloning platform

Wheat germ cell-free methods provide an important approach for the production of eukaryotic proteins. We have developed a protein expression vector for the TNT^® SP6 High-Yield Wheat Germ Cell-Free (TNT WGCF) expression system (Promega) that is also compatible with our T7-based Escherichia coli intracellular expression vector pET15_NESG. This allows cloning of the same PCR product into either one of several pET_NESG vectors and this modified WGCF vector (pWGHisAmp) by In-Fusion LIC cloning (Zhu et al. in Biotechniques 43:354–359, 2007). Integration of these two vector systems allowed us to explore the efficacy of the TNT WGCF system by comparing the expression and solubility characteristics of 59 human protein constructs in both WGCF and pET15_NESG E. coli intracellular expression. While only 30% of these human proteins could be produced in soluble form using the pET15_NESG based system, some 70% could be produced in soluble form using the TNT WGCF system. This high success rate underscores the importance of eukaryotic expression host systems like the TNT WGCF system for eukaryotic protein production in a structural genomics sample production pipeline. To further demonstrate the value of this WGCF system in producing protein suitable for structural studies, we scaled up, purified, and analyzed by 2D NMR two ¹⁵N-, ¹³C-enriched human proteins. The results of this study indicate that the TNT WGCF system is a successful salvage pathway for producing samples of difficult-to-express small human proteins for NMR studies, providing an important complementary pathway for eukaryotic sample production in the NESG NMR structure production pipeline.     

Haemolytic-uraemic syndrome complicating shigella dystentery in south Indian children.

Shigella dysentery caused 65% of all cases of acute renal failure (ARF) seen in children treated at the Christian Medical College Hospital, Vellore, during the 33 months ending September 1977. In the 40 children with ARF secondary to shigella dysentery, haematological findings suggested that they were suffering from the haemolytic-uraemic syndrome, and glomerular hypercellularity and fibrin deposition were present in all 12 patients whose renal histology could be studied. Peritoneal dialysis was the main element of treatment: 43% of children who underwent dialysis improved, compared with only 25% of those who did not undergo dialysis. The haemolytic-uraemic syndrome precipitated by bacillary dystentery is therefore the most important cause of ARF in children aged under 5 years in Tamil Nadu and the adjoining area of Andhra Pradesh.