Focus
on Research
Penn State Intercom......June
21, 2001
'Smart meter' knows when
concrete
has reached the proper solidity
By Vicki Fong
Public Information
University engineers have developed a "smart" maturity meter to estimate and to signal by phone when newly poured concrete bridge supports, pavements and highway surfaces have reached the correct hardness and strength to be opened to traffic or the next phase of construction.
"This method of estimating the strength of concrete can save taxpayer money in reduced cost of quality control and assurance testing," said Paul Tikalsky, associate professor of civil and environmental engineering and a developer of the prototype. "In addition, the meter provides information on the status of the actual structure rather than on representative concrete samples, the method most often used today to estimate concrete strength."
The prototype and accessory technology were developed by Tikalsky and David G. Tepke as part of Tepke's master's degree research. Tepke completed his master's degree program in December and is now a doctoral candidate at the University.
The new maturity meter is the result of integrating digital phone technology with an existing concrete monitoring concept. The concept, Tikalsky said, has been around since the 1940s but has only recently been employed in meters on the commercial market. The Penn State prototype is a "next generation" meter that the developers estimate will cost less than those currently available. In addition, the meter provides real time evaluation and quality control information with cellular technology.
Ambient temperature, the heat generated by the chemical reactions in the curing process itself and the variability in the concrete mixture, as well as other factors, influence the rate at which concrete structures achieve their intended strength. When concrete is poured to create a structure, small sample castings are made, for test purposes, to represent how the concrete is gaining strength in the actual structure.
The prototype uses the fact that the internal temperature of the concrete can be directly related to the time it takes to mature. Only a minimal number of castings need to be made for the method to be effective. To determine the internal temperature, the prototype uses simple thermocouple technology and then integrates it with a computer program-net-on-a-microchip, along with cell phone technology, to provide a "smart" monitoring component.
In the prototype, sensor wires are snaked through the concrete forms before the cement is poured. After the cement is in place, the wires are connected to the maturity meter which is, in turn, connected to a digital cell phone. By calling up the phone, the developers can download the data and use software they have developed to convert the temperature data into a maturity rating.
The meter is expected to cost about $2,000 when it is commercially available and to reduce substantially the test castings that need to be made. Since an average of 200 castings are required for each concrete bridge upright, for example, the potential savings represents a significant part of the quality control and assurance testing budget.
Vicki Fong can be reached at VFong@psu.edu.
Computer model predicts
outcome of DNA shuffling
By A'ndrea Messer
Public
Information
Industries using DNA shuffling to improve enzymes, therapeutic proteins, vaccines and viral vectors may soon have a computational method for predicting the number and likely locations of crossovers, according to a research team.
"To date, the application of these methods has been based on experience and empirical methods and there was no model to understand the process which can be time consuming, expensive and of uncertain outcome," said Costas D. Maranas, assistant professor of chemical engineering. "We used thermodynamics and reaction engineering to evaluate and model this complex reaction network so we can now predict where the DNA from different parent genes will recombine."
DNA shuffling uses related genes from different species or genes with related function, fragments them and reassembles then through recombination. Researchers then place recombined genes into Escherichia coli to identify which new genes produce usable or potentially interesting products. Those genes that express a potentially interesting protein or enzyme are again fragmented and reassembled to form new recombinant genes. The process continues until a protein with the desired qualities is found.
The computer program was developed by Maranas; Gregory L. Moore, graduate student in chemical engineering; Stefan Lutz, postdoctoral fellow in chemistry; and Stephen J. Benkovic, Evan Pugh professor of chemistry and holder of the Eberly Chair in Chemistry.
The mathematical model, which provides a predictive framework for DNA shuffling, looked into how fragment length, annealing temperature, sequence identity and the number of shuffled parent sequences affect the number, type and distribution of crossovers along the length of reassembled sequences.
A'ndrea Messer can be reached at aem1@psu.edu.
Astronomers report
discovery of 2
most distant objects in the universe
The discovery of the two most distant objects ever observed in the universe was announced earlier this month by Donald Schneider, professor of astronomy and astrophysics and chair of the Sloan Digital Sky Survey Quasar Science Group, at a press conference during the American Astronomical Society meeting in Pasadena, Calif.
"We are trying to learn how early in the history of the universe the first stars and galaxies formed," Schneider said.
"This is the first time any object has been detected beyond redshift 6, which is about 800 million years after the Big Bang," Schneider explained. "One of them is probably a black hole about 1 million times the mass of our sun, so models of the formation of our universe now will have to explain how such an object could have formed so early," he added.
Schneider, who has held many previous records for the discovery of "most distant" quasars, has been the organizer of the Sloan Digital Sky Survey's quasar science group since its inception in the early 1990s, helping to assure that its scientists achieve the projects research goals for quasars, the most luminous objects in the universe. His announcement is part of the first public release of data from the Sloan Digital Sky Survey, a large international team.
Schneider described the observation of two quasars with respective redshifts of 6.0 and 6.2. The redshift of an object directly indicates the relative size of the universe when the light was emitted: light from a redshift 6.2 quasar left that object when the universe was 7.2 times smaller than it is today. The two new quasars break the previous distance record established by last year's SDSS discovery of a quasar at redshift 5.8. The data he presented also reveal still another quasar of redshift 5.8.
"Quasars are precocious galaxies whose massive black holes began accreting matter, lighting them up when the universe was less than 800 million years old," said Xiaohui Fan of the Institute for Advanced Study in Princeton, N.J., who led the team within the Quasar Science Group that identified the quasars. "They allow us to study the birth of galaxies, and the first supermassive black holes."