Hand picking

The biologically important anti-/8-phenylalanine, /8-2-thienylalanine (39), has been resolved into antipodes through enzymatic resolution with carboxypeptidase/ The pharmacologically important 3-piperidino-l,i-bis-2-thienyl-l-butene (40), which crystallizes as. a conglomerate, has been resolved by hand picking. ... 

To understand how this method of resolution works, let s see what happens when a racemic mixture of chiral acids, such as (+)- and (-)-lactic acids, reacts with an achiral amine base, such as methylamine, CH3NH2. Stereochemically, the situation is analogous to what happens when left and right hands (chiral) pick up a ball (achiral). Both left and right hands pick up the ball equally well, and the products—ball in right hand versus ball in left hand—are mirror images. In the same way, both ( H- and (-)-lactic acid react with methylamine equally... 

Studies initiated by the author in CSIRO (13) seek to throw light on the role of the various macerals by studying the conversion, under catalytic hydrogenation conditions, in Tetralin as vehicle, of maceral concentrates from a high volatile bituminous coal. Some preliminary results, given in Fig. 3, show conversions as almost complete for the hand picked vitrain (>90% vitrinite) from a high volatile bituminous coal (Liddell seam N.S.W., 83.6% carbon and 43% volatile matter both expressed on a dry ash-free basis). However, it is evident that the conversion of the whole coal increases rapidly with increase in hydrogen pressure (under otherwise similar conditions - batch autoclave, 4h. 400°C). 

Figure 3. Effect of hydrogen pressure on conversion of Liddell coal (O), untreated coal (+) demineralized coal (A), hand-picked vitrain. Reaction temperature = 400°C reaction time = 4 hr.

Preparation of cotton bract extracts. Figure 1 is a flow chart showing our procedures for preparing the various bract extracts. Dried bracts (frost killed) were hand picked just prior to harvest from cotton fields in the Lubbock, Texas area. These were stored at room temperature. Extracts were freeze-dried and stored at -4°C. For inhalation challenge by our subjects each extract was reconstituted with water or saline, as indicated, at a concentration equivalent to the standard crude extract. This Insured that for challenge purposes components were not concentrated as purification progressed. 

Preparation of Other Antigenic Materials. Cotton plant tissues (stem, leaf, burr), cotton gin trash, baled cotton, clean cotton lint, both hand picked in the field and from plants grown in the greenhouse, cottonseed proteins, cottonseed hulls, house dust, and flax, soft hemp, sisal, and jute fibers, were extracted with deionized water. The purification process was, however, stopped to correspond to f-3 (see Figure 1). 

There have been reports of reactions between house dust and cotton dust antibodies (38) and of allergens in cottonseed proteins by Spies et al T39). Also, byssinosis is uncommon in cottonseed crushing mills. Therefore we looked for the presence of antigens in water extracts of house dust, cottonseed hulls, cottonseed kernel proteins and clean hand picked cotton fibers that had not been baled. The results in Figure 5 indicate that house dust does not contain antigens common to those found in cotton dust. 

What to do Hand-pick larvae several times weekly and drop them into soapy water. Till crop residues into the soil before adults emerge in spring. Attract native parasitic wasps by planting pollen- and nectar-rich flowers. 

What to do Where this pest is a regular problem, grow leeks under fine mesh netting to keep the moths out Once plants are infested, there is no control other than hand-picking of caterpillars and cocoons from the leaves, or removing the whole plant Clear up all plant debris at harvest Dig over the leek beds. Encourage predators... 

From the above analysis, it can be seen that D in Pick s first law J = -DVC (Equation 3-6) may be either positive or negative (accounting for uphill diffusion), and it can vary from positive to negative along a spinodal decomposition diffusion profile. If, on the other hand. Pick s law is modified as J = -(T>/y)Va (Equation 3-61), then V is always positive in a binary system. 

Later, Pasteur 15) had arrived at the general stereochemical criterion for a chiral or dissymmetric molecular structure. Thus, the specific rotations of the two sets of sodium ammonium tartrate crystals in solution, isolated from the racemic mixture by hand-picking, were equal in magnitude and opposite in sign, from which Pasteur inferred that enantiomorphism of the dextro- and laevorotatory crystals is reproduced in the microscopic stereochemistry of the (+)- and (—)-tartaric acid molecules. The term dissymmetry or chirality is used when there is no superimposability between the two enantiomers, as seen in Sect. 2.1. 

---