A CO2 laser has the advantages of being high in power and having many laser lines in the 9–11 µm infrared region. Thus, a CO2 laser photoacoustic spectrometer (PAS) can have a multi-component measurement capability for many gas compounds that have non-zero absorption coefficients at the laser lines, and therefore can be applied for measuring several volatile organic compounds (VOCs) in the human breath. We have developed a CO2 laser PAS system for detecting acetone in the human breath. Although acetone has small absorption coefficients at the CO2 laser lines, our PAS system was able to obtain strong photoacoustic (PA) signals at several CO2 laser lines, with the strongest one being at the 10P20 line. Since at the 10P20 line, ethylene and ammonia also have significant absorption coefficients, these two gases have to be included in a multi-component measurement with acetone. We obtained the lowest detection limit of our system for the ethylene, acetone, and ammonia are 6 ppbv, 11 ppbv, and 31 ppbv, respectively. We applied our PAS system to measure these three VOCs in the breath of three groups of subjects, i.e., patients with lung cancer disease, patients with other lung diseases, and healthy volunteers.

We propose a new L-R symmetry model where the L-R symmetry transformation reverses both the L-R chirality and the local quantum number. We add to the model a global quantum number F whose value is one for fermions (minus one for anti fermion) and vanishes for bosons. For each standard model (SM) particle, we have the corresponding L-R dual particle whose mass is very large and which should have decayed at the current low energy level. Due to the global quantum number F , there is no Majorana neutrino in the model but a Dirac seesaw mechanism can still occur and the usual three active neutrinos oscillation can still be realized. We add two leptoquarks and their L-R duals, for generating the baryon number asymmetry and for facilitating the decay of the L-R dual particles. The decay of the L-R dual particles will produce a large entropy to the SM sector and gives a mechanism for avoiding the big bang nucleosynthesis constraint.

DECY-13 cyclotron is a radioisotope production cyclotron developed by PSTA. In a cyclotron, it is important to understand magnetic fields and electric field distribution for the proton beam trajectories. This paper describes the distribution of the magnetic field from the experimental measurement. Magnetic field has been converted into 3-dimensional data by extrapolation. Data validation was done by comparing the Opera3D simulation and used in simulations of the beam trajectories. Simulations were carried out by using Scilab 5.4.1 and the Runge-Kutta (RK4) approximation method. The parameters used in DECY-13 cyclotron were 40 kV Dee voltage with a radiofrequency (RF) 77.66 MHz and a fourth-harmonics type. The calculations and simulations result showed the beam could pass through the puller at the distance of the ion source with a puller was 6 mm and the optimum distance of 4 mm. The largest difference in error at z = 6 mm was 0.023 T of the average magnetic field 1.275 T. The phase acceptance in horizontal and vertical motion in the central region was about 38 Degrees from -19° to 19°. This experimental and simulation data could be used as a reference for DeCY-13 cyclotron magnetic and electric field distribution profiles.

<p>Photoacoustic tomography imaging research has been conducted to distinguish several types of materials. The photoacoustic tomography imaging system used in this study uses a diode laser as a source of radiation and a condenser microphone as a detection tool. The sample is a combination of two types of materials, namely plasticine + iron wire, plasticine + cardboard, plasticine + mica plastic, and mica plastic + cardboard. Optimum setting of laser modulation frequency and duty cycle system to distinguish images from plasticine samples + iron wire and plasticine + cardboard, i.e., 19 kHz and 50%, while to recognize images from plasticine samples + mica plastic and mica plastic + cardboard, which is 19.5 kHz and 50%. The photoacoustic tomography image system used can detect and image the sample clearly, the striking color difference between one material, and another shows the difference in sound intensity.</p>

Using a CO2 laser photoacoustic spectroscopy with intracavity setup and multicomponent method we have done measurement on the ammonia, ehtylene and acetone gas concentrations in the breath of liver disease patients and in the healthy volunteers. The results of multicomponent analysis show that the average concentration of ammonia gas obtained from the breath of liver disease patients and healthy volunteers are (3.27 ± 0.75) and (1.34 ± 0.24) ppm, respectively. The highest and the lowest ammonia gas concentration of liver disease patients are 4.77 and 1.99 ppm. While, the highest and the lowest ammonia gas concentration of healthy volunteers are 1.89 and 1.08 ppm. For the ethylene and acetone concentrations, we found no significant difference between the average concentrations in the liver disease patients and in the healthy volunteers.