Drop trajectory predictions and their importance in the design of spray dryers

A knowledge of the trajectories of atomized droplets in both the nozzle zone (where the droplets are rapidly decelerating from their initial high velocity) and in the free-entrainment zone (where the droplets are conveyed by the drying gas) is required for the design of spray dryers, since it governs the evaporative capacity and thermal efficiency of the chamber, while affecting the moisture content and general quality of the product through the control of the drying time.

The trajectories of droplets in three-dimensional motion were determined theoretically in both zones. In the case of two-fluid pneumatic atomizers, the characteristics of the jet of atomizing fluid were found to be important in both the zones.

Predictions of droplet trajectories were tested in an experimental circular cocurrent spray-drying chamber with a conical bottom, in which the drying air was introduced tangentially near the top. Water was used as the feed material. A study was made of the effects of liquid feed rate and temperature, drying air flowrate and temperature, and of nozzle position on the thermal efficiency and evaporative capacity of the chamber. The results were interpreted in the light of the droplet trajectories predicted.     

An electrospray-ionization mass spectrometer with new features

The construction and performance of an electrospray-ionization mass spectrometer with new features are described. The mass spectrometer consists of a newly designed electrospray ion-source that is plugged directly into a modified commercial quadrupole mass spectrometer with the ions entering the mass analyzer through a long metal capillary tube and three stages of differential pumping. The present ion source differs from previous designs in the combination of techniques employed in the transportation and desolvation of solvated biomolecule ions, prior to mass analysis. Transport of ionized entities between atmospheric pressure and vacuum is carried out through a 203 mm long stainless steel capillary tube with a 0.5 mm bore. Desolvation is effected by the use of controlled heat transfer through the long capillary tube and collisional activation in a region of reduced pressure between the capillary tube exit and the skimmer. Desolvation with this system is convenient and effective and does not involve the strong countercurrent flows of gases that have been used by all previous workers. The effects on the spectra of peptides of capillary tube temperature and desolvation collision energy are investigated. Electrospray-ionization mass spectrometric results are described for thirteen proteins with molecular masses ranging from 5000 to 77,000 Da. The performance of the present instrument, with respect to mass accuracy and sensitivity, is comparable with previously reported systems. The effect of protein concentration in solution on the electrospray mass spectrometric response and charge-state distribution is discussed.     

A fundamental problem in linear inequalities with applications to the travelling salesman problem

We consider a system ofm linearly independent equality constraints inn nonnegative variables:Ax = b, x 0. The fundamental problem that we discuss is the following: suppose we are given a set ofr linearly independent column vectors ofA, known asthe special column vectors. The problem is to develop an efficient algorithm to determine whether there exists a feasible basis which contains all the special column vectors as basic column vectors and to find such a basis if one exists. Such an algorithm has several applications in the area of mathematical programming. As an illustration, we show that the famous travelling salesman problem can be solved efficiently using this algorithm. Recent published work indicates that this algorithm has applications in integer linear programming. An algorithm for this problem using a set covering approach is described.This research has been partially supported by the ISDOS research project and the National Science Foundation under Grant GK-27872 with the University of Michigan.     

New method for determining total dietary fiber by liquid chromatography

The molecular weight limit of water-soluble dietary fiber (SDF) determined by the Prosky method was studied by liquid chromatography (LC). It was confirmed that only SDF with an average degree of polymerization of 12 or higher can be determined by the Prosky method. Total dietary fiber (TDF) was determined by 2 additional methods using LC. In the first method, the total quantity of insoluble dietary fiber (IDF) and high molecular weight SDF (HMSDF) was determined according to the modified Prosky method (MES-TRIS buffer-based). The quantitatively collected final filtrate was analyzed by LC for the quantity of low molecular weight SDF (LMSDF), and the 2 quantities were totaled to obtain TDF. TDF values thus determined for rice, polished or unpolished, soybean flour, and pressed barley were higher than those determined by the Prosky method by approximately 6, 3.5, and 3.5%, respectively. In the second method, direct determination by LC analysis was done on samples after enzymatic treatment according to the Prosky method. Results showed that the determination of LMSDF, in particular, was highly accurate and more effective. In both of these methods, the quantity of LMSDF was determined from its chromatographic peak area ratio to glucose as an internal standard, which was produced by hydrolysis.     

Studies towards the total synthesis of Phostriecin

A synthetic approach toward the phostriecin, an antitumor natural product is described. The key features of the present synthesis are Wittig reaction, synthesis of homoallylic alcohol using Brown’s protocol (alkoxyallylboration) and RCM for the creation of unsaturated lactone moiety of phostriecin.     

A Rapid and Efficient Stereoselective Synthesis of (Z)‐ and (E)‐Allyl Bromides from Baylis–Hillman Adducts Using Bromo(dimethyl)sulfonium Bromide

Treatment of Baylis–Hillman adducts 1 with bromo(dimethyl)sulfonium bromide, Br(Me₂)S⁺Br^?, in MeCN was found to stereoselectively afford (Z)‐ and (E)‐allyl bromides 2 . The reaction is rapid at room temperature, high‐yielding, and highly stereoselective.     

Peptide map procedure using immobilized protease cartridges in tandem for disulfide linkage identification of neu differentiation factor epidermal growth factor domain

Immobilized proteolytic enzyme cartridges were used to rapidly digest neu differentiation factor EGF domain in order to obtain improved peptide maps useful for assignment of disulfide linkages. The procedure described here involves an on-line digestion of proteins using immobilized trypsin and endoproteinase Glu-C cartridges connected in series, followed by on-line RP-HPLC separation of the peptides. The entire process can be automated using a commercially available workstation; and the total time required for both proteolytic digestion and the HPLC separation can be shortened to within 1 h. Using these immobilized columns, we demonstrated that disulfide structure assignment of the EGF domains of recombinant human neu differentiation factor can be performed by isolation of individual disulfide-containing peptides followed by assignment of disulfide linkages with prompt fragmentation of peptides using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The use of immobilized protease cartridges in tandem eliminates undesirable digestion artifacts associated with longer digestion time and higher protease-to-substrate ratio and results in the development of a reproducible and high quality peptide map.     

A highly efficient stereoselective synthesis of (Z)- and (E)-allyl iodides from Baylis-Hillman adducts

A highly efficient synthesis of (Z)- and (E)-allyl iodides has been accomplished by treatment of Baylis-Hillman adducts with iodine and triphenylphosphine in methylene chloride at room temperature. The method is associated with mild reaction conditions, high yields and excellent stereoselectivity.     

Pseudoguaianolides from the Flowers of Parthenium hysterophorus

Two new pseudoguaianolide‐type sesquiterpene lactones, named deacetyltetraneurin A ( 3 ) and hysterone E ( 4 ), were isolated from flowers of the plant Parthenium hysterophorus L., along with the seven known compounds parthenin ( 1 ), coronopilin, tetraneurin A, 8‐β‐hydroxycoronopilin, scopoletin, hysterone D, and conchasin A ( 2 ). The structures of all the compounds were deduced by means of elemental analysis and extensive spectroscopic (1D and 2D NMR) studies, and confirmed for 3 and 4 by X‐ray crystallographic analysis.