Caving performance through the integration of microseismic activity and numerical modeling at DOZ-PT Freeport, Indonesia

This article describes an undergoing research at PT Freeport,Indonesia,in which the main goal is to use the microseismic information recorded as a result of mining to analyze cave propagation and stress performance on the actual production and fixed in-frastructure.At the moment,several numerical experiments have been conducted to correlate the mining activity with the microseis-mic events using the data collected during year 2005 and 2006.As a result of the preliminary analysis a micro-and a macrocracking envelop were proposed on the basis of computation of stress behavior at the location of the events.Stresses have been computed us-ing standard elastic continuous boundary element models.The correlation between the average source radius and the stress perform-ance has provided a method to propose a macrocracking criterion.Several techniques have been tested to nucleate the microseismic activity around different geological features.This last attempt was aimed to look at potential overstresses induced over the undercut and extraction level drifts.A method was devised to integrate the microseismicity into a 3-dimensional ride distribution model.This model has shown to be very effective to quantify the overstress induced as a result of computing volumetric microseismieity density.The volumetric microseismic model showed to induce overstress up to 10 MPa over a period of two months.The future work will concentrate on the calibration of the integrated model with actual damage observations made at the current mining infrastructure.     

An overview on the cellulose based conducting composites

Biopolymer based composites have been employed in numerous applications with increasing interest not only due to renewable, eco-friendly nature, but also because of the flexibility in processing conditions and competitive cost of their end products. The conductive materials from biopolymers have been found applicable in robots, medical imaging, sensitive membranes, actuators, visual displays, electronic wiring and shielding, and components in batteries. Cellulose is one of the most abundant biopolymers in the nature, which has received special attention for development of conducting materials due to biocompatibility for protein and drug immobilization and ability to form the composites with synthetic polymers. The present review is aimed to provide concisely the current status in this field of conducting composites from cellulose, with brief discussions of associated problems and future applications.     

Glycan modifying enzymes in luminal fluid of rat epididymis: are they involved in altering sperm surface glycoproteins during maturation?

Testicular spermatozoa undergo morphological and biochemical alterations, collectively termed epididymal maturation, in the intraluminal environment of epididymis. As a result of these modifications, the spermatozoon becomes a motile and functionally competent cell capable of undergoing capacitation and binding to the zona pellucida, the extracellular coat that surrounds the mammalian oocyte. Although details of all the changes are not fully known, several studies provide evidence suggesting that sperm plasma membrane undergoes extensive biochemical changes, including organization and modification of surface glycoproteins as spermatozoa transit from the proximal to the distal epididymis. In this article, I have attempted to summarize results with two sets of glycoprotein (glycan)-modifying enzymes, namely, glycohydrolases (hydrolytic enzymes) and glycosyltransferases (synthetic enzymes) present in the epididymal luminal fluid (LF). The in vitro experimental approaches described in this report demonstrate that: 1) a PNA-positive glycoprotein(s) (containing O-linked glycan) of 135-150 kDa subunit molecular mass which is present on the surface of caput (but not the cauda) spermatozoa can be degalactosylated by the enzymatic digestion with LF beta-D-galactosidase; and 2) an N-linked glycan chain(s) which is present on a sperm surface glycoprotein (apparent subunit molecular mass of 86 kDa) can be fucosylated in vitro when distal caput sperm (or sperm plasma membrane-rich fractions) are incubated in the presence of a nucleotide sugar (GDP[(14)C]fucose). Combined, these results strongly suggest a role for the glycan-modifying enzymes in degalactosylation and fucosylation of sperm surface glycoproteins during epididymal transit.     

A review of the bioactivity and flavor properties of the exotic spice “andaliman” (Zanthoxylum acanthopodium DC.)

Andaliman (Zanthoxylum acanthopodium DC.) is a plant endemic to North Sumatera, Indonesia. It has been used as food ingredient because of its unique properties of its pericarp, such as its citrus-like aroma, warm peppery flavor, and its ability to induce a tingling sensation. However, the pericarp is easily degraded by environmental and processing conditions. Therefore, preservation techniques, such as encapsulation and drying, have been proposed to protect the flavor. Moreover, andaliman also has some potential biological activities related to its antimicrobial, antioxidant, and anti-inflammatory properties. Thus, this plant may have many health benefits and uses. This review discusses the flavor profiles and bioactive compounds of andaliman, in addition to its applications in the food industry as a flavoring ingredient.