Etichetă: detector chimic

Nanoparticulele polimerice fluorescente îndreaptă degetul spre urme de dispozitive explozive (Fluorescent polymer nanoparticles point the finger at traces of explosive devices )

Loturile de bombe ar putea fi contracarate cu ajutorul unui sistem portabil pentru detectarea urmelor de explozivi exploziva folosind nanoparticule polimerice fluorescente, dezvoltat de A * STAR. Imprimate pe hârtie, acești polimeri prezintă o performanță de detecție a explozivului mult mai robustă decât materialele anterioare cu proprietăți similare ( Polymer Chemistry , poli (trifenil ethene) și poli (tetraphenyl ethene): sinteza, proprietatea de emisie indusă de agregare și aplicarea ca hârtie senzori pentru detectarea efectivă a nitro-compușilor ” ).
Multe metode au fost dezvoltate pentru a detecta urme de explozivi de mare intensitate, cum ar fi trinitrotoluenul (TNT), dar majoritatea necesită instrumente analitice de laborator, cum ar fi detectorii de absorbție UV sau spectrometrele de masă, spune Jianwei Xu de la Institutul A * Engineering, care a condus lucrarea. „Ne-am propus să dezvoltăm o alternativă portabilă, rapidă, ieftină și foarte sensibilă”.

Posted: Sep 08, 2017

Fluorescent polymer nanoparticles point the finger at traces of explosive devices

(Nanowerk News) Bomb plots could be thwarted with the help of a portable system for detecting traces of high explosives using fluorescent polymer nanoparticles, developed by A*STAR. Coated on to paper, these polymers display an explosive-detection performance far more robust than previous materials with similar properties (Polymer Chemistry, „Poly(triphenyl ethene) and poly(tetraphenyl ethene): synthesis, aggregation-induced emission property and application as paper sensors for effective nitro-compounds detection”).
Many methods have been developed to detect traces of high explosives such as trinitrotoluene (TNT), but most require large, lab-based analytical instruments such as UV absorption detectors or mass spectrometers, says Jianwei Xu from the A*STAR Institute of Materials Research and Engineering, who led the work. “We aimed to develop a portable, quick, inexpensive and highly sensitive alternative.”
polymer-coated polymer readily could detect fingerprints contaminated with traces of four common high explosives
The polymer-coated polymer readily could detect fingerprints contaminated with traces of four common high explosives, including TNT.
Xu focused on fluorescent polymers whose light emission dims when exposed to vapors of molecules such as TNT that contain ‘nitro-groups’ — the nitrogen-rich structure that give high explosives their energetic properties.
Although explosive-detecting fluorescent polymers have been developed before, there have been obstacles to their practical use, Xu explains. Some lost part of their fluorescence in solid form through a process called aggregation-caused quenching. Others lacked the necessary porosity for explosives vapor penetration, only retaining an effective response when formed in layers of around 2.5 nanometers — so thin, the sensor would be very difficult to fabricate cheaply.
Xu and his colleagues have been developing polymers that, rather than losing their light emission in the solid state, become brighter, an effect known as aggregation-induced emission (AIE). “Our previous research demonstrated that porous films obtained from AIE active copolymers show a strong response to the vapor of nitro-compounds,” says Xu.
The team has now developed two new polymers, poly(triphenyl ethene) (PTriPE) and poly (tetraphenyl ethene) (PTPE), designed to maximize AIE, porosity and nitro group sensitivity. The polymers’ multiple bulky phenyl groups help keep them rigid and maximize light emission following aggregation. But in the presence of nitro-groups, electron transfer between polymer and analyte rapidly quenches the light.
“Paper sensors fabricated by absorbing the polymer nanoparticles on to filter paper showed high sensitivity for nitro-compound particles,” says Xu. PTriPE proved to be the pick of the pair, detecting TNT at a concentration of five parts per billion, even in polymer layers 1000 nanometers thick.
“This technology could be used at airports, ports and for border control for detecting explosives in any explosive-contaminated containers, clothing, boxes or bags,” says Xu. “We are seeking co-operation with industry to commercialize this technology.”
Source: A*STAR

Read more: Fluorescent polymer nanoparticles point the finger at traces of explosive devices

Micul laser terahertz ar putea fi folosit pentru imagistică, detectarea chimică(Ttiny teraherz laser could be used for imaging, chimical detection)

Radiația Terahertz – banda spectrului electromagnetic dintre microunde și lumina vizibilă – are aplicații promițătoare în imagistică medicală și industrială și detecție chimică, printre alte utilizări

Stimp15

Tuner lasere pentru îmbunătățirea spectroscopiei în infraroșu(Tunable lasers to improve infrared spectroscopy)

a creat un nou laser revoluționar, cu bandă largă, reglabilă, care are implicații majore pentru detectarea drogurilor și a explozivilor.Robustul, tot laserul solid, poate fi reglat rapid pentru a emite în intervalul lungimii de undă care cuprinde regiunea critică a „amprentelor digitale” în care cele mai multe caracteristici moleculare sunt absorbite și identificate prin detectarea în infraroșu. În experimente, laserul și-a demonstrat capacitatea de a capta amprenta spectrală unică a gazelor.

Posted: Jun 09, 2016

Tunable lasers to improve infrared spectroscopy

(Nanowerk News) A new development from Northwestern Engineering’s Manijeh Razeghi could be another tool for protecting our borders.
Supported by the Department of Homeland Security, Razeghi’s lab has created a new, revolutionary, broad-band tunable infrared laser that has major implications for the detection of drugs and explosives.
The robust, all solid-state laser can be rapidly tuned to emit in the wavelength range that encompasses the critical “fingerprint” region where most molecular features are absorbed and identified through infrared sensing. In experiments, the laser has demonstrated its ability to capture the unique spectral fingerprint of gases.
“The only moving part in the entire system is the fan used to keep the laser cool,” said Manijeh Razeghi, Walter P. Murphy Professor of Electrical Engineering and Computer Science. “This is a major advantage over existing systems that require mechanical parts to achieve tuning, and we expect to demonstrate remarkable stability.”
The initial, patent-pending results have been published in the June 8 issue of Nature Scientific Reports („Monolithically, widely tunable quantum cascade lasers based on a heterogeneous active region design”). The research and development of the laser system is the culmination of more than 18 years of quantum cascade laser development work at Northwestern’s Center for Quantum Devices.
The laser has been integrated into a system that contains all of the laser driver electronics and tuning software necessary for integration into a spectroscopy system. It produces a stable, single-aperture spot less than 3 millimeters in diameter that is suitable for standoff detection and is capable of linear or random access scanning with stabilization times of less than 1 millisecond per wavelength.
Source: Northwestern University

Read more: Tunable lasers to improve infrared spectroscopy

IARPA dorește un instrument magic de detectare a tuturor chimicalelor(IARPA wants A Magical All-In One Chemical Detection Tool)

Punctul de control TSA pentru detectarea chimicalelor din explozivi, detectarea reziduurilor metalelor pe blaturi și „identificarea pulberii albe”, printre altele

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