Simulation of Drying Using a Kiln Model

A mathematical model was developed for simulating a convective batch lumber drying process. The model incorporates mass and heat transfer relationships within the lumber stack, as well as thermodynamic properties of the wood and drying air. It takes into account the change of air properties along the stack and its effect on the mass and heat transfer parameters. The model relies on a drying rate function that is an empirical correlation based on single-board tests. A drying rate function for western hemlock (Tsuga heterophylla) lumber was developed. The drying rate function was obtained based on experiment results from 500 small boards dried over a range of conditions used in commercial practice. The model was first validated against data available in the literature and then against large batches of hemlock dried in a laboratory kiln. In both cases, the model output was in good agreement with the average moisture content, the drying rates, and the temperatures measured in the larger batches.     

Submicrometer Aerosol Mass Distributions of Emissions from Boilers,Fireplaces, Automobiles,Diesel Trucks,and Meat-Cooking Operations

The predominant peak in the mass distribution emitted from each source measured in this study occurs at or below about 0.2 μm in particle diameter, whereas the Los Angeles atmospheric aerosol contains peaks at a variety of sizes in the range between 0.1 and 1.0 μm in particle diameter, including peaks at sizes larger than 0.2 μm. This suggests that considerable modification of the primary aerosol size distribution occurs because of subsequent processes in the atmosphere. The data presented here are intended for use in defining the size distribution of the primary combustion source effluent for use with mathematical models of the evolution of the atmospheric aerosol size distribution.     

Fluorescence Particle Counter for Detecting Airborne Bacteria and Other Biological Particles

We have constructed a laser-based particle counter that detects the fluorescence, as well as the elastic scattering, from individual airborne particles as they traverse a laser beam. This fluorescence particle counter (FPC) can detect fluorescence from μm-sized Bacillus subtilis spore agglomerates when illuminated with intense light at 488 nm from an argon ion laser, either ～ 0.7 kW cm^?2 extracavity or ～ 50 kW cm^?2 intracavity. We suspect that flavins in the spores are the molecules primarily responsible for the fluorescence, because the peak fluorescence emission of the biological materials at this excitation wavelength is in the range 530–550 nm, which is characteristic of flavins. Fluorescence from kaolin, hematite, and polystyrene particles was not detectable; the lack of fluorescence indicates that the FPC may be able to differentiate between biological and nonbiological aerosols. The FPC samples aerosol-laden air at a rate of ～ 1 mL s^?1, and is capable of measuring aerosol concentrations up to several thousand per milliliter. The FPC may be helpful in detecting and characterizing airborne bacteria and other airborne particles of biological origin.     

Discussion on “Change-Points: From Sequential Detection to Biology and Back” by David Siegmund

Abstract

Motivated by Professor Siegmund's article and his other works in the area of change-point analysis and its biomedical applications, we discuss approaches to change-point–related problems that involve parameters of unknown dimension.     

Oxidative Folding of Peptides with Cystine‐Knot Architectures: Kinetic Studies and Optimization of Folding Conditions

Bioactive peptides often contain several disulfide bonds that provide the main contribution to conformational rigidity and structural, thermal, or biological stability. Among them, cystine‐knot peptides—commonly named “knottins”—make up a subclass with several thousand natural members. Hence, they are considered promising frameworks for peptide‐based pharmaceuticals. Although cystine‐knot peptides are available through chemical and recombinant synthetic routes, oxidative folding to afford the bioactive isomers still remains a crucial step. We therefore investigated the oxidative folding of ten protease‐inhibiting peptides from two knottin families, as well as that of an HIV entry inhibitor and of aprotinin, under two conventional sets of folding conditions and by a newly developed procedure. Kinetic studies identified folding conditions that resulted in correctly folded miniproteins with high rates of conversion even for highly hydrophobic and aggregation‐prone peptides in concentrated solutions.     

Ligand Binding Promiscuity of Human Liver Fatty Acid Binding Protein: Structural and Dynamic Insights from an Interaction Study with Glycocholate and Oleate

Human liver fatty acid binding protein (hL‐FABP) has been reported to act as an intracellular shuttle of lipid molecules, thus playing a central role in systemic metabolic homeostasis. The involvement of hL‐FABP in the transport of bile salts has been postulated but scarcely investigated. Here we describe a thorough NMR investigation of glycocholate (GCA) binding to hL‐FABP. The protein molecule bound a single molecule of GCA, in contrast to the 1:2 stoichiometry observed with fatty acids. GCA was found to occupy the large internal cavity of hL‐FABP, without requiring major conformational rearrangement of the protein backbone; rather, this led to increased stability, similar to that estimated for the hL‐FABP:oleate complex. Fast‐timescale dynamics appeared not to be significantly perturbed in the presence of ligands. Slow motions (unlike for other proteins of the family) were retained or enhanced upon binding, consistent with a requirement for structural plasticity for promiscuous recognition.     

Ahp Cyclodepsipeptides: The Impact of the Ahp Residue on the “Canonical Inhibition” of S1 Serine Proteases

S1 serine proteases are by far the largest and most diverse family of proteases encoded in the human genome. Although recent decades have seen an enormous increase in our knowledge, the biological functions of most of these proteases remain to be elucidated. Chemical inhibitors have proven to be versatile tools for studying the functions of proteases, but this approach is hampered by the limited availability of inhibitor scaffold structures with the potential to allow rapid discovery of selective, noncovalent small‐molecule protease inhibitors. The natural product class of Ahp cyclodepsipeptides is an unusual class of small‐molecule canonical inhibitors; the incorporation of protease cleavage sequences into their molecular scaffolds enables the design of specific small‐molecule inhibitors that simultaneously target the S and S′ subsites of the protease through noncovalent mechanisms. Their synthesis is tedious, however, so in this study we have investigated the relevance of the Ahp moiety for achieving potent inhibition. We found that although the Ahp residue plays an important role in inhibition potency, appropriate replacement with β‐hydroxy amino acids results in structurally less complex derivatives that inhibit serine proteases in the low micromolar range.     

Single‐Molecule Unzipping Force Analysis of HU–DNA Complexes

The genome of bacteria is organized and compacted by the action of nucleoid‐associated proteins. These proteins are often present in tens of thousands of copies and bind with low specificity along the genome. DNA‐bound proteins thus potentially act as roadblocks to the progression of machinery that moves along the DNA. In this study, we have investigated the effect of histone‐like protein from strain U93 (HU), one of the key proteins involved in shaping the bacterial nucleoid, on DNA helix stability by mechanically unzipping single dsDNA molecules. Our study demonstrates that individually bound HU proteins have no observable effect on DNA helix stability, whereas HU proteins bound side‐by‐side within filaments increase DNA helix stability. As the stabilizing effect is small compared to the power of DNA‐based motor enzymes, our results suggest that HU alone does not provide substantial hindrance to the motor's progression in vivo.