On the thermochemistry of gypsum

Heating gypsum below 100°c gives rise to limiting values of weight loss around that of the hemihydrate formation whatever is the time of heating. Calcination at 100°c and above, on the other hand, causes a continuous loss in weight as the time is prolonged, leading to γ-anhydrite when adequate time is given. In most of the examined samples a resistant state, with trace amounts of residual water, is reached towards the end of the dehydration process. Such residual water is driven off completely below the transformation temperature of γ- to β-CaSO₄.     

The addition of paclitaxel to continuous infusion 5-fluorouracil is an active regimen for metastatic breast cancer

We investigated tissue staining for Bcl-2 and Bax proteins, which regulate apoptosis, as indicators of chemotherapeutic effect in patients with gastric cancer. In 23 patients with gastric carcinoma biopsy specimens were obtained endoscopically prior to chemotherapy and stained immunohistochemically with anti-Bcl-2 and anti-Bax antibodies. Patients then were treated with continuous infusion of 5-FU and cisplatin. No correlation was seen between chemotherapeutic effect and Bcl-2 or Bax alone. However, among the Bax-positive cases, the patients with Bcl-2-positive tumors were significantly more chemoresistant (p = 0.036) and had worse prognoses (p = 0.008) than Bcl-2-negative cases. Therefore, immunohistochemical staining for Bcl-2 protein may predict chemotherapeutic efficacy or guide specific therapeutic choices in treating Bax-positive tumors.     

Busulfan-based regimens and allogeneic bone marrow transplantation in patients with myelodysplastic syndromes

Preparative regimens containing busulfan (BU) followed by allogeneic bone marrow transplantation (BMT) were used in 27 consecutive patients with myelodysplastic syndromes (MDS). The median age was 33 years (range, 4 to 54). Ten were female and 17 male. Sixteen patients had primary MDS, 11 other patients had antecedent hematologic diseases or developed MDS after cytotoxic and/or radiation therapy. Six patients had leukemic transformation and received antileukemic therapy before BMT. Pre-BMT cytogenetic studies showed complex chromosomal abnormalities in 13 patients, a simple abnormality in 5 patients, and normal chromosome in 8 patients. Three BU-based preparative regimens were used: 1 patient received BU 4 mg/kg orally (PO) daily for 4 days and cyclophosphamide (CY) 50 mg/kg intravenously (IV) daily for 4 days (BUCY-4); 24 patients received BU 4 mg/kg PO daily for 4 days, cytosine arabinoside (ara-C) 2 g/m2 IV every 12 hours for 4 doses, and CY 60 mg/kg IV daily for 2 days (BAC); and 2 patients with preceding Fanconi anemia received BU 2 mg/kg PO daily for 4 days followed by total lymphoid irradiation of 5 Gy. Seventeen of 27 patients are alive with no evidence of disease. Ten patients have died: 2 from hepatic veno-occlusive disease, 3 from sepsis, 1 from a cerebral bleed, 1 from a massive gastrointestinal (GI) bleed associated with acute graft-versus-host disease, 1 from hemolytic uremic syndrome with adult respiratory distress syndrome, 1 from bronchiolitis obliterans, and the only patient who did not engraft died from acute myeloid leukemia. Regimen-related toxicities (RRT) include GI tract (diarrhea, 14; stomatitis, 11), liver (9), cardiac (1), and skin (5). Patients who received a genotypically matched marrow graft had a significantly better disease-free survival (DFS) than patients who received a nongenotypic marrow graft (P = .02). The Kaplan-Meier analysis projects an overall DFS of 56% +/- 13% and 78% +/- 10% for patients who received a genotypically matched marrow graft. With the exception of a child who did not engraft, there was no relapse of MDS or leukemia. Excellent DFS, acceptable RRT, and the ease of administration are advantages of this regimen.     

Thermal stabilities of mixtures of trichlorofluoroethane and lubricating fluids contained in copper sealed tubes

Halocarbons are suitable working fluids in Rankine-cycle engines. However each engine's performance will deteriorate as a result of the thermal breakdown of the working fluid-lubricant mixture. Therefore, for a specified working fluid, the choices of lubricant and lubricant: fluid mixture ratio that will ensure that the mixture is chemically stable at the maximum expected cycle temperature, when in contact with the constructional materials of the engine, are vital. Using trichlorofluoroethane as the working fluid, and operating at a maximum cycle temperature of 140°C, experimental observations revealed that the Clavus mineral lubricating oil, with a lubricant: fluid mixture ratio of up to 10% by weight, in contact with copper, is a good choice.     

Photochemically assisted solar energy storage using eriochrome black-T in solar flat collector

The criteria for cis-trans photoisomerization of eriochrome black-T (EBT) in the flat-plate collector system, which consists of endoergic photochemical reaction, has been investigated. The efficiencies of this collector in both summer and winter have been compared with blank (distilled water only) and colored liquid (non-isomer-dye-absorbing in the same wavelength range). The photochemical storage efficiency was found to be higher in winter than in summer. The optimum efficiency for this photoisomerization-thermal reversion cycle was found by varying with the pumping rate of the liquid to match the value of rate constant of cis to trans reaction. The stability of (EBT) has been studied under different environmental conditions.     

The critical nucleation temperature of stacking fault tetrahedra in gold

The nucleation of stacking fault tetrahedra in quenched high purity gold was traced via measurements of electrical resistivity. A critical nucleation temperature exists above which the nucleation process bccomes increasingly difficult. This temperature is function of the quenched in concentration of vacancies, and reflects the necessity of a small cluster for the nucleation process.