in the present study the freshwater algae of siahdarvishan river were sampled on a montly basis from december 2007 through november 2008. three sampling stations (gaght roudkhan , shahkezr dame and talab laleh ) were chosen in the river. some physical and chemical parameters (water temperature , total hardness , nitrate , nitrite, phosphate and ph) of water samples were measured. a total of 84 ...

STATEMENT OF PROBLEM Two potential problems commonly identified with a denture base incorporating a resilient liner are failure of the bond between acrylic resin and soft liner material, and loss of resiliency of the soft liner over time. Since patients may drink different beverages, it is important to evaluate their effects on physical properties of soft lining materials. PURPOSE The objecti...

Rainbow trout embryos and larvae were exposed to 0, 0.1, and 1 microg/L total silver (as AgNO3) in water of three different hardnesses (soft water [2 mg/L as CaCO3], moderately hard water [150 mg/L], and hard water [400 mg/L]) in a flow-through system from fertilization to swim-up (64 d). The objective of the study was to investigate the effects of water hardness on chronic silver toxicity. In ...

A human can perceive the hardness of an object by tapping its surface. We compared the ranked subjective hardness values and physical properties of objects, including their stiffness, viscosity, density, and Shore hardness, and the frequencies and time constants of the natural vibrations caused by tapping. The stiffness, frequency, and viscosity exhibited a relatively strong positive correlatio...

In a very recent article (Torrent-Sucarrat et al., J Comput Chem 2007, 28, 574), we have shown how to evaluate the global hardness for polyatomic molecules using a hardness kernel approximation. We present here an extension of this previous work by improving the model used to evaluate the hardness kernel and the Fukui function. In addition, the concept of the local hardness is analyzed in detai...

In this paper, we address the scheduling model with discretely compressible release dates, where processing any job with a compressed release date incurs a corresponding compression cost. We consider the following problem: scheduling with discretely compressible release dates to minimize the sum of makespan plus total compression cost. We show its NP-hardness, and design an approximation algori...

OBJECTIVES To establish if there is an association between ground hardness and injury risk in junior cricket. DESIGN Nested case-series of players who played matches on specific grounds with objective ground hardness measures, within a prospective cohort study of junior community club cricket players. METHODS Monitoring of injuries and playing exposure occurred during 434 matches over the 2...