Toward Demystifying the Mohs Hardness Scale

Today, the Mohs scale is used profusely throughout educational systems without any persuasive understanding of the fundamental principles. Why one mineral has a scratch hardness over the next culminating in a scale of 1 (chalk) to 10 (diamond) has no atomistic or structure‐sensitive basis that explains this outcome. With modern computationally based atomistic and multiscale models, there is increasing promise of defining the pressure and rate‐dependent parameters that will allow a fundamental understanding of the Mohs scale. This study principally addresses the combined fracture and plasticity parameters that qualitatively affect fracture at the nanoscale. A physical model wherein the crack tip under a scratch is shielded by dislocations is supported by molecular dynamics (MD) simulations in both ductile aluminum and brittle silicon carbide. Next, this model is applied to nanoindentation data from the literature to produce a ranking of Mohs minerals based on their fundamental properties. As such, what is presented here is a first step to address the flow and fracture parameters ultimately required to provide a figure of merit for scratch hardness and thus the Mohs scale.     

Urban crash-related child pedestrian injury incidence and characteristics associated with injury severity

Objective

Describe age-based urban pedestrian versus auto crash characteristics and identify crash characteristics associated with injury severity.

Materials and methods

Secondary analysis of the 2004–2010 National Highway and Traffic Safety Administration database for Illinois. All persons in Chicago crashes with age data who were listed as pedestrians (n = 7175 child age ≤19 yo, n = 16,398 adult age ≥20 yo) were included. Incidence and crash characteristics were analyzed by age groups and year. Main outcome measures were incidence, crash setting, and injury severity. Multivariate logistic regression analysis was performed to estimate injury severity by crash characteristics.

Results

Overall incidence was higher for child (146.6 per 100,000) versus adult (117.3 per 100,000) pedestrians but case fatality rate was lower (0.7% for children, 1.7% for adults). Child but not adult pedestrian injury incidence declined over time (trend test p < 0.0001 for <5 yo, 5–9 yo, and 10–14 yo; p < 0.05 for 15–19 yo, p = 0.96 for ≥20 yo). Most crashes for both children and adults took place during optimal driving conditions. Injuries were more frequent during warmer months for younger age groups compared to older (χ²p < 0.001). Midblock crashes increased as age decreased (p < 0.0001 for trend). Most crashes occurred at sites with sub-optimal traffic controls but varied by age (p < 0.0001 for trend). Crashes were more likely to be during daylight on dry roads in clear weather conditions for younger age groups compared to older (χ²p < 0.001). Daylight was associated with less severe injury (child OR 0.93, 95% CI 0.87–0.98; adult OR 0.90, 95% CI 0.87–0.93).

Conclusion

The incidence of urban pedestrian crashes declined over time for child subgroups but not for adults. The setting of pedestrian crashes in Chicago today varies by age but is similar to that seen in other urban locales previously. Injuries for all age groups tend to be less severe during daylight conditions. Age-based prevention efforts may prove beneficial.     

Exploring scenarios for the future of energy management in UK property

The most appropriate responses to the energy management of buildings from now until 2050 are investigated through a process of scenario planning. A qualitative, explorative approach was undertaken to develop four 2050 scenario end-states resulting from an axis of two critical uncertainties not closely correlated: the attitudes of society towards sustainability; and the availability of energy. These scenarios were applied to the property industry through expert workshops, from which trends and themes were identified. The findings are that the property industry should prepare for a transitional period with an uncertain outlook. Therefore, it would be prudent for this industry to focus on resilient performance under a diverse set of futures, and plausible shock events, rather than optimizing for today's conditions. This could be challenging in a sector that works on relatively long time scales. Aspects that should be incorporated into property industry strategy are suggested: responding to the potential effects of climate change; understanding what drives communities and investing in buildings that are significant to the community's functions; considering transport links as key to successful property investments; adopting the latest technological innovations; and becoming more ‘full service’ and interdisciplinary. A need for a paradigm shift in the industries' practices was also identified.

Les réponses les plus appropriées à la gestion énergétique des bâtiments d'ici 2050 sont étudiées en ayant recours à un processus de planification par scénarios. Une approche qualitative exploratrice a été adoptée afin de développer quatre conclusions de scénario pour 2050, résultant d'un axe formé par deux incertitudes cruciales qui ne sont pas étroitement corrélées: les attitudes de la société envers la durabilité et la disponibilité de l'énergie. Ces scénarios ont été appliqués à l'industrie de l'immobilier par l'intermédiaire d'ateliers d'experts, grâce auxquels des tendances et des thèmes ont été identifiés. Il en ressort que l'industrie de l'immobilier devrait se préparer à une période de transition offrant des perspectives incertaines. En conséquence, il serait prudent que cette industrie concentre ses efforts sur le maintien de solides performances face à différents avenirs possibles, et à des évènements chocs plausibles, plutôt que sur une optimisation par rapport aux conditions d'aujourd'hui. Ceci pourrait être difficile dans un secteur qui travaille sur des échelles de temps relativement longues. Il est suggéré des aspects qui devraient être intégrés à la stratégie de l'industrie de l'immobilier: répondre aux effets potentiels du changement climatique; comprendre ce qui constitue le moteur des collectivités et investir dans des bâtiments qui soient significatifs pour les fonctions de la collectivité; considérer les liaisons de transport comme essentielles pour des investissements immobiliers réussis; adopter les dernières innovations technologiques; et devenir davantage « un service complet » et interdisciplinaire. A également été identifiée la nécessité d'un changement de paradigme dans les pratiques des industries.

bâtiments, gestion énergétique, planification future, secteur de l'immobilier, résilience, scénarios, incertitude     

高容量移动应用的NOR闪存和NAND闪存

高速数据传输网络和多媒体服务的大量部署使得具有更大的存储量成为新型手机和3G手机共有的要素。这些手机的存储量有望超过1Gb,而低端3G手机的存储能力将军少是32Mb。     

Experimental investigation of solid particles flow in a conical spouted bed using radioactive particle tracking

Solid particles flow in a conical spouted bed is characterized by radioactive particle tracking. The influence of operating conditions on key parameters of this flow is evaluated and discussed: the morphology of the solid bed is not strongly influenced by the forces exerted by the gas on the solid particles, but rather by geometrical considerations; the particles spend approximately 8% of their time in the spout in all experiments; it is the force exerted on the solid particles by the gas that directly controls the volumetric flow rate between adjacent regions, and not the amount of particles in the bed; as U/U_ms increases, the volume of solid particles in the annulus decreases, the volume of solid particles in the fountain increases and the volume of solid particles in the spout remains constant. Correlations to predict key flow parameters as functions of operating conditions are also established and discussed. © 2015 American Institute of Chemical Engineers AIChE J, 62: 26–37, 2016     

Long-Term Measures of Dyslipidemia,Inflammation, and Oxidative Stress in Rats Fed a High-Fat/High-Fructose Diet

Inflammation and oxidative stress are thought to be involved in, or associated with, the development of obesity, dyslipidemia, hepatic steatosis, and insulin resistance. This work was designed to determine the evolution of inflammation and oxidative stress during onset and progression of hepatic steatosis and glucose intolerance. Seventy-five male Wistar rats were divided to control and high-fat high-fructose (HFHFr) groups. A subgroup of each group was sacrificed at 4, 8, 12, 16, and 20 weeks. HFHFr-fed rats exhibited overweight, glucose intolerance, and hepatic steatosis with increased contents of hepatic diacylglycerols and ceramides. The HFHFr diet increased hepatic interleukin 6 (IL-6) protein and adipose tissue CCL5 gene expression and hepatic nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity but not mitochondrial reactive oxygen species (ROS) production. The HFHFr diet decreased plasma and liver levels of isoprostanoid metabolites as well as plasma thiobarbituric acid-reactive substance (TBARS) levels. Hepatic glutathione content was decreased with a moderate decrease in superoxide dismutase (SOD) and glutathione peroxidase (GPx) with the HFHFr diet. Overall, HFHFr diet led to hepatic lipid accumulation and glucose intolerance, which were accompanied by only moderate inflammation and oxidative stress. Most of these changes occurred at the same time and as early as 8 or 12 weeks of diet treatment. This implies that oxidative stress may be the result, not the cause, of these metabolic alterations, and suggests that marked hepatic oxidative stress should probably occur at the end of the steatotic stage to result in frank insulin resistance and steatohepatitis. These findings need to be further evaluated in other animal species as well as in human studies.     

Effect of liquid flavor supplementation of the diet on dairy cows in the transition period

A 9-wk trial was conducted to study the performance of 24 Holstein cows during the transition period (3 wk prepartum to 6 wk postpartum). Cows were assigned to either a control or liquid-flavored (0.52 mL/kg of feed) total mixed ration in a randomized complete block design. The diets contained corn silage, alfalfa haylage, cottonseed, and a grain mix based on ground corn and soybean meal. Cows were fed to ensure 10% orts, and the diet provided (on a dry matter basis) 13% crude protein, 32% acid detergent fiber, 44% neutral detergent fiber, and 1.54 Mcal/kg of NEL prepartum and 17.5% crude protein, 30% acid detergent fiber, 40% neutral detergent fiber, and 1.57 Mcal/kg of NEL postpartum. An additional 2.3 kg of alfalfa hay was fed during the first 5 d postpartum. Weekly means of dry matter intake (DMI), milk yield, milk protein, milk fat, SNF, somatic cell counts, and body weight (BW) were analyzed using a repeated measures procedure. There was no effect of treatment on these variables, and least squares means were 16.9 and 15.7 kg/d for DMI, 38 and 35.3 kg/d for milk yield, 3.10 and 3.11% for milk protein, 3.69 and 3.74% for milk fat, 8.37 and 8.16% for SNF, 1.99 x 10(5) and 4.33 x 10(5) for somatic cell count, and 631 and 651 kg for BW for cows fed control and flavored diets, respectively. Individual cow daily DMI data were fitted to an exponential model describing pre- and postpartum feed consumption [DMI = a - b x e(-c x t), where DMI was measured in kg, a = asymptotic DMI, b = potential fractional increase in DMI, c = fractional rate of increase in DMI, and t = days prior to calving or days in milk]. Fractional rates of increase in DMI were similar: 0.139 and 0.123/d for control and flavored diets, respectively. Data for both groups were separately analyzed using multiple regression with 3.5% fat-corrected milk as the dependent variable and BW and DMI as independent variables. More BW was mobilized per unit increase in 3.5% fat-corrected milk in cows fed the control than in cows fed the flavored diet. Cows fed the control diet tended to be in more negative energy balance during early lactation than cows fed the flavored diet. It was concluded that feeding flavor improved energy balance of cows in early lactation and may reduce the risk of health or reproductive problems.     

Control of Clostridium perfringens spores by green tea leaf extracts during cooling of cooked ground beef, chicken, and pork

We investigated the inhibition of Clostridium perfringens spore germination and outgrowth by two green tea extracts with low (green tea leaf powder [GTL]; 141 mg of total catechins per g of green tea extract) and high (green tea leaf extract [GTE]; 697 mg of total catechins per g of extract) catechin levels during abusive chilling of retail cooked ground beef, chicken, and pork. Green tea extracts were mixed into the thawed beef, chicken, and pork at concentrations of 0.5, 1.0, and 2.0% (wt/ wt), along with a heat-activated (75 degrees C for 20 min) three-strain spore cocktail to obtain a final concentration of approximately 3 log spores per g. Samples (5 g) of the ground beef, chicken, and pork were then vacuum packaged and cooked to 71 degrees C for 1 h in a temperature-controlled water bath. Thereafter, the products were cooled from 54.4 to 7.2 degrees C in 12, 15, 18, or 21 h, resulting in significant increases (P < 0.05) in the germination and outgrowth of C. perfringens populations in the ground beef, chicken, and pork control samples without GTL or GTE. Supplementation with 0.5 to 2% levels of GTL did not inhibit C. perfringens growth from spores. In contrast, the addition of 0.5 to 2% levels of GTE to beef, chicken, and pork resulted in a concentration-and time-dependent inhibition of C. perfringens growth from spores. At a 2% level of GTE, a significant (P < 0.05) inhibition of growth occurred at all chill rates for cooked ground beef, chicken, and pork. These results suggest that widely consumed catechins from green tea can reduce the potential risk of C. perfringens spore germination and outgrowth during abusive cooling from 54.4 to 7.2 degrees C in 12, 15, 18, or 21 h of cooling for ground beef, chicken, and pork.     

Modulation of Mechanical Interactions by Local Piezoelectric Effects

Piezoelectricity is a well‐established property of biological materials, yet its functional role has remained unclear. Here, a mechanical effect of piezoelectric domains resulting from collagen fibril organisation is demonstrated, and its role in tissue function and application to material design is described. Using a combination of scanning probe and nonlinear optical microscopy, a hierarchical structuring of piezoelectric domains in collagen‐rich tissues is observed, and their mechanical effects are explored in silico. Local electrostatic attraction and repulsion due to shear piezoelectricity in these domains modulate fibril interactions from the tens of nanometre (single fibril interactions) to the tens of micron (fibre interactions) level, analogous to modulated friction effects. The manipulation of domain size and organisation thus provides a capacity to tune energy storage, dissipation, stiffness, and damage resistance.