化学法清洗硅片过程中清除颗粒的机理(英文)

对化学法清洗硅片过程中消除颗粒的机理作了定量的探讨。颗粒的清除是由于化学蚀刻和颗粒与表面排斥力共同作用的结果。首次提出了最浅蚀刻深度和最小蚀刻速度的概念。最浅蚀刻深度可通过颗粒与表面间作用能的关系进行计算。是小蚀刻速度则可通过蚀刻侧形进行计算。研究结果对于优化化学法清洗过程和设计高性能清洗液都具有重要意义。     

Pretender punishment induced by chemical signalling in a queenless ant

Animal societies are stages for both conflict and cooperation. Reproduction is often monopolized by one or a few individuals who behave aggressively to prevent subordinates from reproducing (for example, naked mole-rats, wasps and ants). Here we report an unusual mechanism by which the dominant individual maintains reproductive control. In the queenless ant Dinoponera quadriceps, only the alpha female reproduces. If the alpha is challenged by another female she chemically marks the pretender who is then punished by low-ranking females. This cooperation between alpha and low-rankers allows the alpha to inflict punishment indirectly, thereby maintaining her reproductive primacy without having to fight.     

Insect communication: 'no entry' signal in ant foraging

Forager ants lay attractive trail pheromones to guide nestmates to food, but the effectiveness of foraging networks might be improved if pheromones could also be used to repel foragers from unrewarding routes. Here we present empirical evidence for such a negative trail pheromone, deployed by Pharaoh's ants (Monomorium pharaonis) as a 'no entry' signal to mark an unrewarding foraging path. This finding constitutes another example of the sophisticated control mechanisms used in self-organized ant colonies.     

Only full-sibling families evolved eusociality

Arising from M. A. Nowak, C. E. Tarnita & E. O. Wilson 466, 1057-1062 (2010); Nowak et al. reply. The paper by Nowak et al. has the evolution of eusociality as its title, but it is mostly about something else. It argues against inclusive fitness theory and offers an alternative modelling approach that is claimed to be more fundamental and general, but which, we believe, has no practical biological meaning for the evolution of eusociality. Nowak et al. overlook the robust empirical observation that eusociality has only arisen in clades where mothers are associated with their full-sibling offspring; that is, in families where the average relatedness of offspring to siblings is as high as to their own offspring, independent of population structure or ploidy. We believe that this omission makes the paper largely irrelevant for understanding the evolution of eusociality.     

Parasitic Cape honeybee workers, Apis mellifera capensis, evade policing.

Relocation of the Cape honeybee, Apis mellifera capensis, by bee-keepers from southern to northern South Africa in 1990 has caused widespread death of managed African honeybee, A. m. scutellata, colonies. Apis mellifera capensis worker bees are able to lay diploid, female eggs without mating by means of automictic thelytoky (meiosis followed by fusion of two meiotic products to restore egg diploidy), whereas workers of other honeybee subspecies are able to lay only haploid, male eggs. The A. m. capensis workers, which are parasitizing and killing A. m. scutellata colonies in northern South Africa, are the asexual offspring of a single, original worker in which the small amount of genetic variation observed is due to crossing over during meiosis (P. Kryger, personal communication). Here we elucidate two principal mechanisms underlying this parasitism. Parasitic A. m. capensis workers activate their ovaries in host colonies that have a queen present (queenright colonies), and they lay eggs that evade being killed by other workers (worker policing)-the normal fate of worker-laid eggs in colonies with a queen. This unique parasitism by workers is an instance in which a society is unable to control the selfish actions of its members.     

Enforced altruism in insect societies

Cooperation among workers and their seeming altruism result from strict policing by nestmates.     

Trail geometry gives polarity to ant foraging networks

Pheromone trails are used by many ants to guide foragers between nest and food. But how does a forager that has become displaced from a trail know which way to go on rejoining the trail? A laden forager, for example, should walk towards the nest. Polarized trails would enable ants to choose the appropriate direction, thereby saving time and reducing predation risk. However, previous research has found no evidence that ants can detect polarity from the pheromone trail alone. Pharaoh's ants (Monomorium pharaonis) produce elaborate trail networks throughout their foraging environment. Here we show that by using information from the geometry of trail bifurcations within this network, foragers joining a trail can adaptively reorientate themselves if they initially walk in the wrong direction. The frequency of correct reorientations is maximized when the trail bifurcation angle is approximately 60 degrees, as found in natural networks. These are the first data to demonstrate how ant trails can themselves provide polarity information. They also demonstrate previously unsuspected sophistication in the organization and information content of networks in insect societies.