Human plague in the United States.
To the Editor:— The Aug 5, 1962 issue ofThe Journalcarried a cover picture of a painting by Arnold Bocklin entitled "Plague" and an article entitled "Human Plague in the United States" by Caten and Kartman. This article and the caption next to the cover picture carry misleading statements which I would like to call to your attention. Discussing the distribution of wild-rodent plague in the United States, Caten and Kartman state, "The reason why plague does not extend beyond the 100th meridian is poorly understood." While it is true that all human cases associated with wild rodents for which adequate data are available have been acquired west of the 100th meridian, and this corresponds quite well to the known distribution of wild-rodent plague, as shown by Caten and Kartman, very limited surveys of wild rodents and fleas for plague have been conducted east of the 100th meridian. 1 Many investigators believe that wild-rodent plague does not extend into the eastern states, largely on the basis of the distribution of human cases associated with wild rodents. On the other hand, plague-infected wild rodents or their ectoparasites have been identified from over 130 counties in the western
THE PREVENTION OF PLAGUE IN THE LIGHT OF NEWER KNOWLEDGE
Knowledgc of the nature of the majority of pestilences which scourged the world in bygone ages is, admittedly, vague. It is certain, however, that plague is a disease of grcat antiquity, for, occasionally, some of the oldest records contain descriptions of a disease, sufficiently explicit to remove all doubt of its being plague.' Interest in the nefarious history of this malady has never varied. Pandemics and epidemics have been recorded in detail. However, explanation of the causes of their origin and development, as distinguished from the conditions which have generally been observed to favor their continuance and spread, has always been within the realm of speculation. All that is definitely known is that they were generally associated with unusual seasons, which bring distress and misery : with war and famine and their attendant ills, and with political, social or economic conditions which engender laxity or neglect of ranitary administration and thus hinder or entirely prevent prompt handling of early cases. Plague has acquired its ascendancy, both in the past and present, because knowledge of the different modes by which it spreads has been incomplete and, more frequently, because of ignorance of the biological laws governing these modes. Some of the modes are known. Since others, however, are unknown, there is always a risk that preventive measures employed may only be partially successful in checking and controlling the disease. Plague, the hydra-headed monster, has stretched its tentacles from continent to continent for nearly 3,000 years. Today, in fact, it appears to be even more widespread than during the great epidemics which began in the eleventh century and which, in the fourteenth century, culminated in a pandemic whose destructiveness cannot be matched in historical record. The present pandemic began in 1894, in Hong Kong. Except in India and a few other Asiatic regions, it has not caused a mortality comparable to that of old, although the prevailing types are as severe as in the past and the expansion of the
Thermodynamic analysis of H2 production from CaO sorption‐enhanced methane steam reforming thermally coupled with chemical looping combustion as a novel technology
In this novel paper, a technique for hydrogen production route of CaO sorption‐enhanced methane steam reforming (SEMSR) thermally coupled with chemical looping combustion (CLC) was presented (CLC‐SEMSR), which perceived as an improvement of previous methane steam reforming (MSR) thermally coupled with CLC technology (CLC‐MSR). The application of CLC instead of furnace achieves the inherent separation of CO2 from flue gas without extra energy required. The required heat for the reformer is provided by thermally coupling CLC. The addition of CaO sorbents can capture CO2 as it is formed from the reformer gas to the solid phase, displacing the normal MSR equilibrium restrictions and obtaining higher purity of H2. The Aspen Plus was used to simulate this novel process on the basis of thermodynamics. The performances of this system examined included the composition of reformer gas, yield of reformer gas (YRg), methane conversion (αM), the overall energy efficiency (η), and exergy efficiency (φ) of this process. The effects of the molar ratio of CaO to methane for reforming (Ca/M) in the range of 0–1.2, the molar ratio of methane for combustion to methane for reforming (M(fuel)/M) in the range of 0.1–0.3, and the molar ratio of NiO to methane for reforming (Ni/M) in the range of 0.4–1.2 were investigated. It has been found to be favored by operating under the conditions of Ca/M = 1, M(fuel)/M = 0.2, and Ni/M = 0.8. The most excellent advantage of CLC‐SEMSR was that it could obtain higher purity of H2 (95%) at lower operating temperature (655 °C), as against H2 purity of 77.1% at higher temperature (900 °C) in previous CLC‐MSR. In addition, the energy efficiency of this process could reach 83.3% at the optimal conditions. Copyright © 2014 John Wiley & Sons, Ltd.