Opportunistic

The remaining question is how we got from G3MP2 (OK) = —117.672791 to G3MP2 Enthalpy = —117.667683. This is not a textbook of classical thermodynamics (see Klotz and Rosenberg, 2000) or statistical themiodynamics (see McQuarrie, 1997 or Maczek, 1998), so we shall use a few equations from these fields opportunistically, without explanation. The definition of heat capacity of an ideal gas... 

Pneumogstis carini pneumonia (PCP), the most common of the opportunistic infections, occurs in more than 80% of AIDS patients (13). Toxoplasmosis, a proto2oan infection of the central nervous system, is activated in AIDS patients when the 004 count drops and severe impairment of ceU-mediated immunity occurs. Typically, patients have a mass lesion(s) in the brain. These mass lesions usually respond well to therapy and can disappear completely. Fungal infections, such as CTyptococcalmeningitis, are extremely common in AIDS patients, and Histop/asma capsulatum appears when ceU-mediated immunity has been destroyed by the HIV vims, leading to widespread infection of the lungs, Hver, spleen, lymph nodes, and bone marrow. AIDS patients are particularly susceptible to bacteremia caused by nontyphoidal strains of Salmonella. Bacteremia may be cleared by using antibiotic therapy. 

The immunorestorative potential of inosiplex has been evaluated in several clinical conditions, including post-surgical trauma, cancer patients with concurrent viral infections, and cancer patients receiving radiotherapy or chemotherapy. For example, most (84%) of the surgery patients remained immunologicaHy depressed, but 56% of the inosiplex-treated surgery patients had complete restoration of normal skin test reactivity (probability level < 0.0005). The use of inosiplex as an adjuvant to chemotherapy or radiotherapy appears to be valuable in the prophylaxis against opportunistic infections. 

Nonspecific immunosuppressive therapy in an adult patient is usually through cyclosporin (35), started intravenously at the time of transplantation, and given orally once feeding is tolerated. Typically, methylprednisone is started also at the time of transplantation, then reduced to a maintenance dose. A athioprine (31) may also be used in conjunction with the prednisone to achieve adequate immunosuppression. Whereas the objective of immunosuppression is to protect the transplant, general or excessive immunosuppression may lead to undesirable compHcations, eg, opportunistic infections and potential malignancies. These adverse effects could be avoided if selective immunosuppression could be achieved. Suspected rejection episodes are treated with intravenous corticosteroids. Steroid-resistant rejection may be treated with monoclonal antibodies (78,79) such as Muromonab-CD3, specific for the T3-receptor on human T-ceUs. Alternatively, antithymocyte globulin (ATG) may be used against both B- and T-ceUs. 

Specify operation from Hst of appHcable opportunistic and strategic operations. 

List all opportunistic separations appHcable to given stream (see Table 3). 

Determine which strategic or opportunistic operation should be tried first. 

The thermodynamics and physical properties of the mixture to be separated are examined. VLE nodes and saddles, LLE binodal curves, etc, are labeled. Critical features and compositions of interest are identified. A stream is selected from the source Hst. This stream is either identified as meeting all the composition objectives of a destination, or else as in need of further processing. Once an opportunistic or strategic operation is selected and incorporated into the flow sheet, any new sources or destinations are added to the respective Hsts. If a strategic separation for dealing with a particular critical feature has been implemented, then that critical feature is no longer of concern. Alternatively, additional critical features may arise through the addition of new components such as a MSA. The process is repeated until the source Hst is empty and all destination specifications have been satisfied. 

Separation method selection is governed by a two-tier set of rules for selecting among potential operations. The first tier involves the selection between strategic and opportunistic operations. Strategic separations are favored, as these are known to be required in the flow sheet at some point, as are separations which directly reach a desired product composition. The rules in the first tier state that once all the potential opportunistic and strategic operations have been identified for the current stream, the next step is to determine the order in which these operations should be tried. The foUowing... 

For a binary system, the two possible opportunistic distillations are essentially identical and can be combined to concentrate the feed up to about 68% 2-propanol and produce pure water. The feed and products of the two possible strategic separations are ill-defined, whereas those of the opportunistic separation are known as outlined in Table 6. 

Table 6. Feasible Opportunistic and Strategic Separations for IPA-Water System...

Because a preconcentration step is probably needed to make the final sequence more economical, it is logical to start with the opportunistic separation. This separation produces one of the products, pure water, as the underflow and a concentrated distillate appropriate for feed into either strategic separation. Arbitrarily choosing pervaporation first, the retentate has a composition on the 2-propanol-rich side of the azeotrope, whereas the permeate is pure water. No further strategic separations are required. 

The feed compositions and products of each of these strategic separations remain ill-defined. The unspecified 2-propanol—water mixture, the input to each strategic separation, could be but is not necessarily the original feed composition. The MSA composition (pure hexane in this case) is such that one of the products of the strategic separation is in region II, ie, the strategic separation crosses the distillation boundary. Two opportunistic distillations from... 

The strategy for boundary crossing has been implemented however, by the addition of the hexane another critical feature has been created. Hexane must be regenerated, but it is in a different distillation region than the only remaining unprocessed stream (Ml). In this case the possible boundary crossing strategic operations are Mixer 6 and Decanter 7. Two opportunistic distillations. Fractionators 8 and 9, can also be appHed to Ml (decantation is also a possible opportunistic separation). 

The final loose end in the process is the aqueous decanter product, A7. The hexane must be removed before the mixture can be sent to wastewater treatment, ie, accepted as a water by-product. Two opportunistic separations. Fractionators 12 and 13, are possible. Selection of Fractionator 13 gives pure water underflow, and a distillate similar to D5. Distillate D13 can be recycled back and mixed with D5 without affecting the operation of Mixer 1. AH streams are processed and the flow sheet produces both desired products (Fig. 5b). 

In one possible sequence the MSA composition is chosen as water-saturated methylene chloride expected to be regenerated by decantation. The boundary-crossing strategic operation is to mix the feed with the MSA. The resulting two-phase mixture is opportunistically fractionated to produce the 2-propanol product as bottoms, and a mixture of water—methylene chloride as distillate. This distillate is opportunistically decanted to recover water-saturated methylene chloride MSA for recycle. The aqueous decanter phase is the water product, which optionally may be further purified by... 

If an opportunistic preconcentration of the feed is used instead, an entirely different flow sheet results. In this case the MSA composition is a two-phase mixture of methylene chloride and water. Detailed simulations ate requited to determine which of these (or other) 2-ptopanol dehydration flow sheet alternatives is the economically advantaged process. 

Increasingly, this opportunistic disease occurs in those with a suppressed immune system, especially those with AIDS. The only effective treatment for cryptosporidiosis in AIDS patients who do not respond readily to therapy is spiramycin (48). 

Safety standards tmd practices tend to evolve opportunistically rather than systematically. 

---