An advanced bioprocessing concept for the conversion of waste paper to ethanol

Applied Biochemistry and Biotechnology - Waste paper is a plentiful and low-cost lignocellulosic feed material that may represent the most direct way to penetrate the market with an advanced...     

Modeling scale-up effects on a small pilot-scale fluidized-bed reactor for fuel ethanol production

Applied Biochemistry and Biotechnology - The algorithm generally underpredicted pilot-scale performance, although in some cases, the predicted and actual profiles were similar. The model did a good...     

Performance of reference electrodes with free-diffusion junctions : The Effect of Ionic Strength and Bore Size on Junction with Simple Cylindrical Geometry

The performance of free-diffusion liquid junctions formed in a capillary between saturated potassium chloride solution and a range of solutions with ionic strengths varying from 10^?5 to 0.5 mol kg^?1 is described. Precision, response time and noise associated with convection were adversely affected at ionic strengths less than 10^?3 mol kg^?1. Increasing the bore of the capillary from 0.5 mm to 3 mm also had a detrimental effect. Capillaries with 0.5-mm bore performed optimally with errors <0.2 mV for solutions with ionic strength > 10^?4 mol kg^?1, but deteriorating to 1 mV for 10^?5 mol kg^?1 solutions. Equivalent errors if free-diffusion junctions were used in pH measurements would be 0.003 and 0.017 pH, indicating that, given well-controlled experimental conditions, it is possible to achieve precise measurements in very dilute solutions.     

Synthesis and characterization of technetiumtetrakis(acetonitrile)bis(triphenylphosphine) cationic complexes

A new route to low-valent technetium complexes containing multiple acetonitrile ligands has been developed. The reduction of TcCl(4)(PPh(3))(2) with zinc metal dust in acetonitrile results in the formation of [Tc(CH(3)CN)(4)(PPh(3))(2)][Zn(2)Cl(6)](1/2). The hexafluorophosphate salt of the analogous Tc(II) cation can be prepared via chemical oxidation of the Tc(I) species, and the Tc(I) cation can be regenerated via chemical reduction. The compounds have been characterized in the solid state via single-crystal X-ray crystallography, and in solution via a combination of spectroscopic techniques and cyclic voltammetry. The structural parameters found in the two complexes are similar to each other; however, the difference in oxidation state is reflected, as expected, in the spectroscopic results. The electrochemical data, obtained from cyclic voltammograms of Tc(CH(3)CN)(4)(PPh(3))(2)](PF(6))(n)() (n = 1,2), mirror the synthetic results in that both compounds possess a reversible redox couple at -0.55 V versus ferrocene, which has been assigned to the Tc(II)/Tc(I) couple.     

N-(2-Mercaptoethyl)picolylamine as a diaminomonothiolate ligand for the "fac-[Re(CO)3]+" core

N-(2-Mercaptoethyl)picolylamine (MEPAH) was studied as a potentially biologically relevant ligand for the "fac-[M(CO)(3)](+)" core (M = Re, (99)Tc, (99m)Tc). To this end, the complex Re(CO)(3)(MEPA) was synthesized. The reaction of MEPAH with fac-[Re(CO)(3)(MeCN)(3)](+) took place over the course of seconds, showing the high affinity possessed by this ligand for the "fac-[Re(CO)(3)](+)" core. A single-crystal X-ray diffraction study was performed confirming the nature of Re(CO)(3)(MEPA), a rare mononuclear rhenium(I) thiolate complex. Additional exploration into derivatization of the ligand backbone has afforded the analogous N-ethyl complex, Re(CO)(3)(MEPA-NEt). The high affinity of the ligand for the metal coupled with the ease of its derivatization implies that utilization of this ligand system for the purposes of (99m)Tc-radiopharmaceutical development is promising.     

3‐Oxo‐5β‐24‐norcholanic acid: acid‐to‐acid hydrogen‐bonding catemers employing the rare anti carboxyl conformation in the aggregation of a steroid keto acid

The title ketocarboxylic acid [systematic name: (5R,8R,9S,10S,13R,14S,17R,20R)‐3‐oxo‐24‐norcholanic acid], C₂₃H₃₆O₃, forms acid‐to‐acid hydrogen‐bonding chains [O...O = 2.620 (2) Å and O—H...O = 163 (3)°] in which all carboxyl groups adopt the rare anti conformation, while the ketone group does not participate in the hydrogen bonding. The occurrence and energetics of this conformation are discussed. One intermolecular C—H...O close contact exists, which plays a role in stabilizing the hydrogen‐bonding arrangement.     

Conventional residual liquid junction potentials in dilute solutions

Conventional residual liquid junction potentials were measured between NBS 1:1 phosphate buffer and various dilute solutions with ionic strengths of 1-100 mmol kg^?1, using 3.5 mol kg^?1 potassium chloride as the bridge electrolyte. All junctions were of the free-diffusion type, formed within a 1-mm capillary. The conventional residual junction potential was indistinguishable from zero (± 0.5 mV), for dilute solutions of primary reference standards, for which calculations based on the Henderson equation predict values of 0.8–1.3 mV. Solutions of Tris-HCl (20–100 mmol kg^?1) and dilute HCl (1–50 mmol kg^?1) had appreciable conventional residual liquid junction potentials (1.1–3.3 mV). The experimental values for dilute HCl solutions compare favourably with those calculated with the Henderson equation. These results suggest that the pH of hard waters, measured using the NBS pH scale, will be a good approximation (within 0.01 pH) to pa_H, so that pH can be interpreted in terms of the activity of the hydrogen ions. Further measurements are required to ascertain whether this approximation is true for soft and acidic waters.     

PAP inhibitor with in vivo efficacy identified by Candida albicans genetic profiling of natural products

Natural products provide an unparalleled source of chemical scaffolds with diverse biological activities and have profoundly impacted antimicrobial drug discovery. To further explore the full potential of their chemical diversity, we survey natural products for antifungal, target-specific inhibitors by using a chemical-genetic approach adapted to the human fungal pathogen Candida albicans and demonstrate that natural-product fermentation extracts can be mechanistically annotated according to heterozygote strain responses. Applying this approach, we report the discovery and characterization of a natural product, parnafungin, which we demonstrate, by both biochemical and genetic means, to inhibit poly(A) polymerase. Parnafungin displays potent and broad spectrum activity against diverse, clinically relevant fungal pathogens and reduces fungal burden in a murine model of disseminated candidiasis. Thus, mechanism-of-action determination of crude fermentation extracts by chemical-genetic profiling brings a powerful strategy to natural-product-based drug discovery.     

Parton distribution and decay functions

We define parton distribution and decay functions in QCD and prove some of their basic properties. These include renormalization, light-cone expansions and sum rules.