Photochemical Mechanism of an Atypical Algal Phytochrome

Phytochromes are bilin‐containing photoreceptors that are typically sensitive to the red/far‐red region of the visible spectrum. Recently, phytochromes from certain eukaryotic algae have become attractive targets for optogenetic applications because of their unique ability to respond to multiple wavelengths of light. Herein, a combination of time‐resolved spectroscopy and structural approaches across picosecond to second timescales have been used to map photochemical mechanisms and structural changes in this atypical group of phytochromes. The photochemistry of an orange/far‐red light‐sensitive algal phytochrome from Dolihomastix tenuilepis has been investigated by using a combination of visible, IR and X‐ray scattering probes. The entire photocycle, correlated with accompanying structural changes in the cofactor/protein, are reported. This study identifies a complex photocycle for this atypical phytochrome. It also highlights a need to combine outcomes from a range of biophysical approaches to unravel complex photochemical and macromolecular processes in multi‐domain photoreceptor proteins that are the basis of biological light‐mediated signalling.     

Continuous grinding in a small wet rod mill Part II. Breakage of some common ore minerals

A study has been made of the breakage of galena, marmatite, chalcopyrite and quartz, separately, in a calcite environment in a rod mill. The behaviour of all may be described by the same basic dynamic breakage model, which involves a breakage function, a rate function and a distribution of residence time function. The same breakage and distribution of residence time functions applied to all the minerals but the mean residence times decreased in the order galena > marmatite > chalcopyrite > quartz. Size for size, the values of the rate of breakage constants followed the same sequence.     

基于有限元的疲劳设计分析系统MSC/FATIGUE

简单描述了基于有限元分析结果进行疲劳寿命分析的思路,着重介绍了根据时域载荷输入计算构件内各点弹性应力应变响应的各种方法,以及从弹性应力应变结果近似计算弹塑性应力应变历史,并考虑多轴影响的各种途径;简单介绍了几种包含在ＭＳＣ／ＦＡＴＩＧＵＥ中的疲劳寿命计算方法及其各自的特点。总结了ＭＳＣ／ＦＡＴＩＧＵＥ系统的功能和特点,并给出了一个转向节疲劳分析例子。     

Time course analyses confirm independence of imitative and spatial compatibility.

Imitative compatibility, or automatic imitation, has been used as a measure of imitative performance and as a behavioral index of the functioning of the human mirror system (e.g., Brass, Bekkering, Wohlschlager, & Prinz, 2000; Heyes, Bird, Johnson, & Haggard, 2005; Kilner, Paulignan, & Blakemore, 2003). However, the use of imitative compatibility as a measure of imitation has been criticized on the grounds that imitative compatibility has been confounded with simple spatial compatibility (Aicken, Wilson, Williams, & Mon-Williams, 2007; Bertenthal, Longo, & Kosobud, 2006; Jansson, Wilson, Williams, & Mon-Williams, 2007). Two experiments are reported in which, in contrast with previous studies, imitative compatibility was measured on both spatially compatible and spatially incompatible trials, and imitative compatibility was shown to be present regardless of spatial compatibility. Additional features of the experiments allowed measurement of the time courses of the imitative and spatial compatibility effects both within and across trials. It was found that imitative compatibility follows a different time course from spatial compatibility, providing further evidence for their independence and supporting the use of imitative compatibility as a measure of imitation. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Lifts for evacuation—human behaviour considerations

To predict the time that a building will take to be evacuated in an emergency and to design lift systems capable of dealing with the demand, building designers need an understanding of the likely exiting behaviour of occupants. Because of the inherent difficulties of carrying out research in human behaviour, a number of approaches have been used in this investigation, including analysis of data from past fire events and a number of surveys. The results from this work suggest that the split of occupants using the stairs or lifts to evacuate is governed predominantly by floor level of the occupant and that it is unreasonable to expect that occupants will wait indefinitely for a lift to arrive in an emergency situation. The drop‐off in the percentage of occupants that will continue to wait for a lift with increasing waiting time is dependent on floor height. These results will allow building designers to make more realistic assumptions when designing evacuation strategies incorporating lifts. It is also hoped that a better understanding of the reservations that building users may have about using lifts for evacuation in emergency situations will allow better occupant training programmes to be developed. Copyright © 2011 John Wiley & Sons, Ltd.     

Comparative study on simultaneous leaching of nutrients during bioleaching of heavy metals from sewage sludge using indigenous iron and sulphur oxidising microorganisms

The present study investigated the changes in nutrient profile of sewage sludge during bioleaching in a batch mode of operation. The study identified the optimum bioleaching period at which maximum solubilisation of metals is achieved while maintaining the fertilising property of the bioleached sludge. The bioleaching experiments were performed using anaerobically digested sewage sludge by employing indigenous iron and sulphur oxidising microorganisms. The results showed that bioleaching using sulphur oxidising microorganisms is comparatively advantageous due to the higher solubilisation of heavy metals. However, despite its high potential in solubilisation of heavy metals from the sludge, the bioleaching process resulted in the undesirable dissolution/loss of sludge bound nutrients (nitrogen and phosphorus), thus making the sludge less attractive for land application as a fertiliser. After 16 days of bioleaching about 45% of the nitrogen and 34% of the phosphorus were leached from the sludge using indigenous iron oxidising microorganisms, whereas about 78% of the nitrogen and 56% of the phosphorus were leached using indigenous sulphur oxidising microorganisms. The findings indicated that the fertilising property of the sewage sludge can be maintained by conducting the process for a shorter duration of time (up to 10 days). The optimum bioleaching period was 10 days where about 85%Cu, 71%Ni, 91%Zn and 61%Cr were solubilised from the sludge while the loss of nitrogen and phosphorus was only 56 and 51% respectively, by using sulphur oxidising microorganisms. The heavy metals remaining in the bioleached sludge were mostly in the residual fraction ensuring the safe disposal of bioleached sludge for land application as a fertiliser.

Cette étude examine les changements du profil de nutriment de boues d’épuration lors de la biolixiviation d’un procédé discontinu. L’étude identifie la durée optimale de biolixiviation à laquelle la solubilisation maximale des métaux est achevée tout en maintenant les propriétés fertilisantes de la boue biolixiviée. On a effectué les expériences de biolixiviation en utilisant des boues d’épuration digérées en condition anaérobique et en employant l’oxydation par ferro- ou thiomicroorganismes indigènes. Les résultats ont montré que la biolixiviation par oxydation avec des thiomicroorganismes était comparativement avantageuse grâce à la solubilisation plus élevée des métaux lourds. Cependant, en dépit de son potentiel élevé de solubilisation des métaux lourds de la boue, le procédé de biolixiviation avait pour résultat une dissolution ou une perte indésirables des nutriments liés dans la boue (azote et phosphore), rendant ainsi la boue moins attrayante pour application dans les champs comme engrais. Après 16 jours de biolixiviation, environ 45% de l’azote et 34% du phosphore étaient lixiviés de la boue par oxydation avec des ferromicroorganismes indigènes, alors qu’environ 78% de l’azote et 56% du phosphore étaient lixiviés en utilisant des thiomicroorganismes indigènes. Les constatations indiquent qu’on peut maintenir les propriétés fertilisantes de la boue d’épuration en effectuant le processus sur une durée plus courte (jusqu’à 10 jours). La période optimale de biolixiviation était de 10 jours, pendant lesquels environ 85% du Cu, 71% du Ni, 91% du Zn et 61% du Cr étaient solubilisés à partir de la boue alors que les pertes d’azote et de phosphore étaient seulement de 56% et de 51%, respectivement, en utilisant les thiomicroorganismes. Les métaux lourds qui restaient dans la boue biolixiviée se trouvaient principalement dans la fraction résiduelle, assurant la disposition sécuritaire comme engrais de la boue biolixiviée.     

Granular Dynamics Simulations of Heap Formation: Effects of Feed Rate on Segregation Patterns in Binary Granular Heap

Granular dynamics simulations of a 2D heap formation have been carried out at low- and high-impact feed rates for a 3:1 diameter ratio binary mixture. The data have been analyzed using novel time series and filtering analysis to investigate key representative many-particle dynamic events of the assembly evolution. Spectral analysis of the time series has revealed quite different periodic behavior in the low- and high-impact cases. Segregation occurs in the low-impact case whereas more uniform mixing of the two types of particles arises at high impact, which is consistent with previous experimental observations. The low-impact feed regime is shown to be characterized by discrete surface avalanching manifesting kinetic sieving of the finer particles, in which the large particles move preferentially toward the free surface and segregate in the boundary layer on rolling toward the horizontal base. In contrast, the high-impact feed regime is marked by periodic lateral surging and vertical “pluming” of particles from below toward the free surface.     

Reactivity and mobility of new and old mercury deposition in a boreal forest ecosystem during the first year of the METAALICUS study. Mercury Experiment To Assess Atmospheric Loading In Canada and the US

The METAALICUS (Mercury Experiment To Assess Atmospheric Loading In Canada and the US) project is a whole ecosystem experiment designed to study the activity, mobility, and availability of atmospherically deposited mercury. To investigate the dynamics of mercury newly deposited onto a terrestrial ecosystem, an enriched stable isotope of mercury (202Hg) was sprayed onto a Boreal forest subcatchment in an experiment that allowed us, for the first time, to monitor the fate of 'new' mercury in deposition and to distinguish it from native mercury historically stored in the ecosystem. Newly deposited mercury was more reactive than the native mercury with respect to volatilization and methylation pathways. Mobility through runoff was very low and strongly decreased with time because of a rapid equilibration with the large native pool of "bound" mercury. Over one season, only approximately 8% of the added 212Hg volatilized to the atmosphere and less than 1% appeared in runoff. Within a few months, approximately 66% of the applied 202Hg remained associated with above ground vegetation, with the rest being incorporated into soils. The fraction of 202Hg bound to vegetation was much higher than seen for native Hg (<5% vegetation), suggesting that atmospherically derived mercury enters the soil pool with a time delay, after plants senesce and decompose. The initial mobility of mercury received through small rain events or dry deposition decreased markedly in a relatively short time period, suggesting that mercury levels in terrestrial runoff may respond slowly to changes in mercury deposition rates.     

General processes, rather than "goals," explain imitation errors.

The goal-directed theory of imitation (GOADI) states that copying of action outcomes (e.g., turning a light switch) takes priority over imitation of the means by which those outcomes are achieved (e.g., choice of effector or grip). The object