Hot corrosion Type II of FeCr‐based model alloys for boiler and heat exchanger applications

The hot corrosion Type II of the alloys FeCr20, FeCr20Ni10, FeCr20Ni20, and FeCr20Co10 is investigated at 700°C in air + 0.5% SO₂ with deposits consisting of Na₂SO₄ and a eutectic mixture of Na₂SO₄ and MgSO₄ for 24, 100, and 300 h. The alloying elements nickel and cobalt have a positive influence when tests are conducted using a MgSO₄‐Na₂SO₄ deposit. In this case, they reduce the metal loss and increase the time to the propagation stage. In contrast, when the alloys are exposed with a Na₂SO₄ deposit, these alloying elements increase the metal loss and allow for the transition to the propagation stage because they can form molten phases with the Na₂SO₄. During the incubation stage an oxide scale forms on the FeCr20 alloy, which is thicker than the one formed during exposure without a deposit, and iron oxides are observed, which precipitate in the deposit. The propagation stage occurs by a dissolution and precipitation mechanism forming localized pitting attack. Iron is the main species that dissolves and precipitates, while chromium remains mainly as an oxide beneath the initial surface. The additional elements are found in the pit and in the salt deposit.     

硫酸厂主鼓风机的主要设计准则

论述现代硫酸厂主鼓风机设计时必须考虑的关键因素，通过实例讨论操作费用与投资之间的平衡关系以及对装置竞争力的影响。建议在硫酸厂严酷的操作条件下改进风机特性，提高耐磨性并采用维修友好的设计。     

Immunoreactivity and expression of amylin in gastroenteropancreatic endocrine tumors

Amylin was isolated from human insulinomas, but there has been only preliminary data regarding whether this peptide can also be detected in other types of gastroenteropancreatic endocrine tumors. In the present study, immunohistochemical staining of 87 gastroenteropancreatic endocrine tumors demonstrated amylin immunoreactivity in 21.8% of the neoplasmas. Thirteen of 15 insulinomas, three of 21 gastrinomas, two of 29 nonfunctioning tumors, and one of 18 carcinoids were amylin-immunoreactive. Seventeen of the 19 amylin-immunoreactive tumors were primarily located in the pancreas, but two tumors were found in the intestine. Measurements of amylin messenger RNA expression in a few tumors revealed amylin synthesis in these tumors. Amylin immunoreactivity did not correlate with invasion and metastasis. However, the rate of curative resections was significantly higher in amylin-immunoreactive tumors. These results demonstrate for the first time that amylin immunoreactivity is not restricted to insulinomas and can also occur rarely in endocrine tumors of the intestine.     

Two geometrical isomers of linoleic acid: Improved total syntheses

The total syntheses of 9(Z),12(E)- and 9(E),12(Z)-octadecadienoic acids have been carried out. A useful intermediate in both syntheses, 8-bromo-octanoic acid, recently has become available from commercial sources. This compound has been used to expedite the preparation of these isomers. The remaining carbon atoms were derived from propargyl alcohol along with either 1-heptyne or acetylene and 1-bromopentane. Because the overall yield for each sequence was roughly 15% and there were no extraordinary reaction conditions in any of the synthetic steps, the compounds could be prepared readily in multiple gram quantities. The syntheses of the two compounds were supported by data from a variety of spectroscopic techniques.     

Determination of best shortened linear codes

The quality of a block code is determined by its capability to protect data against undetectable errors and by the number of check bits that are required for that purpose. For a given number of check bits there are codes with optimum bit error detecting capability in shortened block lengths. These codes are determined and tabulated. The residual error characteristics of some of the tabulated codes are compared with those specified in ISO/CCITT or IEC standard data transmission protocols. For block lengths and bit error rates that are typical in process control applications, the residual error rate of the determined codes is more than six orders of magnitude smaller than that of codes specified by widely used standard transmission protocols     

One-step synthesis of functional Co nanoparticles for surface-initiated polymerization

Much effort is conducted to construct artificial objects that are capable of converting chemical or electromagnetic energy into a specific, predetermined motion on the nanoscale. We present results on the synthesis of core–shell nanoparticles capable to be set in rotation by the application of electromagnetic fields. The nanorotors implied in the study are based on the cobalt nanospheres decorated with a stabilizing brush shell composed of poly(?-caprolactone) that is attached by surface-initiated polymerization. The functional cores used as macroinitiators can be fabricated alternatively by a two-step or a one-step process.     

Intra-seasonal NDVI change projections in semi-arid Africa

Early warning systems (EWS) tend to focus on the identification of slow onset disasters such famine and epidemic disease. Since hazardous environmental conditions often precede disastrous outcomes by many months, effective monitoring via satellite and in situ observations can successfully guide mitigation activities. Accurate short term forecasts of NDVI could increase lead times, making early warning earlier. This paper presents a simple empirical model for making 1 to 4 month NDVI projections. These statistical projections are based on parameterized satellite rainfall estimates (RFE) and relative humidity demand (RHD). A quasi-global, 1 month ahead, 1° study demonstrates reasonable accuracies in many semi-arid regions. In Africa, a 0.1° cross-validated skill assessment quantifies the technique's applicability at 1 to 4 month forecast intervals. These results suggest that useful projections can be made over many semi-arid, food insecure regions of Africa, with plausible extensions to drought prone areas of Asia, Australia and South America.