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By solving the density matrix equations in the steady state, we have derived analytical expressions for the absorption, dispersion, and group index of a five-level cascade-type atomic system as functions of laser intensity and frequency, spontaneously generated coherence (SGC), and relative phase of applied fields. The influences of SGC and relative phase on absorption, dispersion, and group index of this system under electromagnetically induced transparency (EIT) are studied. It is shown that the three EIT windows of system become deeper and narrower as the strength of SGC increases. These lead to an increase in the slope and the amplitude of the dispersion curves at three EIT windows. As a result, the amplitude of the group index at these three EIT windows also becomes larger when the strength of SGC increases. In particular, the group index can easily be switched between negative and positive values i.e., the light propagation can easily be converted between superluminal to subluminal modes by adjusting the strength of SGC, relative phase or the coupling laser intensity.

In this paper, a novel degenerate two-level model is proposed to study the behavior of optical bistability (OB) and optical multistability (OM) under the effect of the magnetic field and relative phase. We show that the behavior of the OB can appear in the resonant regime by changing the strength of the external magnetic field. Especially, the result has shown that it is possible to easily convert between OB and OM by adjusting the strength of the external magnetic field or coupling field in the presence of the relative phase. In addition, the influence of the probe detuning and the atomic cooperation parameter on the OB behavior have also been considered. The studied results may be helpful for optical communication applications in optical switching processing and optimization.

We present an analytical model for cross-Kerr nonlinear coefficient in a four-level N-type atomic medium under Doppler broadening. The model is applied to 87Rb atoms to analyze the dependence of the cross-Kerr nonlinear coefficient on the external light field and the temperature of atomic vapor. The analysis shows that in the absence of electromagnetically induced transparency (EIT) the cross-Kerr nonlinear coefficient is zero, but it is significantly enhanced when the EIT is established. It means that the cross-Kerr effect can be turned on/off when the external light field is on or off. Simultaneously, the amplitude and the sign of the cross-Kerr nonlinear coefficient are easily changed according to the intensity and frequency of the external light field. The amplitude of the cross-Kerr nonlinear coefficient remarkably decreases when the temperature of atomic medium increases. The analytical model can be convenient to fit experimental observations and applied to photonic devices.

Surface water contains clay, bacteria, dissolved metals, organic matter, color, other suspended solids. The purpose of coagulation and flocculation is to remove these suspended particles which ensure proper operation in treatment plant. Improper use of coagulant dosage affects water quality after treatment, cause operation problems and production costs. A study is being conducted at a surface water treatment plant at Dong Nai River with the capacity of 300,000 m3/day. The treatment process uses iron alum for coagulation and flocculation. Due to the high corrosion property of iron alum and the residue effects of the quality of treated water, it requires strict control in the treatment process as well as the chemical dosage. The main aim of this study is to determine appropriate amount of alum used for the coagulation-flocculation process. Research method is data collection including: turbidity, pH, flow rate of raw water, dosage of iron alum, lime, polymer used in current treatment process. Then, find the model using iron alum by linear regression analysis and BMA methods on R tool platform. Next, verify the appropriate linear regression model of iron alum by Jar test experiment. Results revealed that the BMA model is not suitable for the application because one Jar test results has a mean turbidity value greater than 4 NTU, which does not meet the water quality requirements after sedimentation tank according to the water treatment regulation. The linear regression analysis showed that raw water turbidity and season are two independent factors related to the alum dosage, of which these two factors explain about 78% of the differences that affect the coagulation-flocculation process. This study was successful in determining the appropriate iron alum dosage for the water treatment plant, which can be applied similarly to build appropriate chemical model for water surface water plants and raw water resources.

This research presents a comparison of the test engine’s performance characteristics fuelled by diesel and waste cooking oil synthetic diesel (WCOSD). Commercial diesel (CD) fuel used in this research was commercial diesel in the market; meanwhile, WCO was manufactured from cooking waste product using Catalytic Cracking Method. The synthesizing process known as Catalytic Cracking Method at pilot scale level using non-food oil such as waste cooking oil to manufacture biodiesel fuel oil in place of diesel with a stable energy output. The results of this research showed that it can be concluded that the engine torque with WCO drop from 1.9 Nm to 5.4 Nm at all speed while the BSFCs drop at almost speed at full load condition compared to that of CD. The BTEs of the engine fuelled with WCOSD are higher than that of the engine fuelled with CD at almost engine speed at full load. The result of this research is the foundation for using WCO in worldwide application.

We develop an analytical approach on electromagnetically induced transparency (EIT) in a Doppler broadened medium consisting of five-level cascade systems excited by a strong coupling and weak probe laser fields. In a weak field limit of the probe light, EIT spectrum is interpreted as functions of controllable parameters of the coupling light and temperature of the medium. The theoretical interpretation of EIT spectrum is applied to the case of 85Rb atoms and compared with available experimental observation. Such an analytical interpretation provides quantitative parameters to control properties of the Doppler broadened EIT medium, and it is useful to find related applications.

Using density-matrix theory, an analytical expression of the self-Kerr nonlinear coefficient of a three-level lambda EIT medium for a weak probe light is derived. Influences of the coupling light and Doppler broadening on the self-Kerr coefficient are investigated and compared to experimental observation with a good agreement. The self-Kerr nonlinearity of the medium is modified and greatly enhanced in the spectral region of EIT window. Furthermore, sign, slope, and magnitude of the self-Kerr coefficient can be controlled with frequency and intensity of the coupling light and temperature of the medium. In particular, for a given set of fixed values of the parameter coupling and probe lights, it is possible to choose an optimized temperature with which to obtain the largest magnitude of the self-Kerr coefficient. Such a controllable Kerr nonlinearity can find interesting applications in optoelectronic devices working with low-light intensity at various temperature conditions.

Animal models such as rats and mice are useful for studying the multiple roles of nitric oxide (NO) in various respiratory disorders. The production of NO is catalyzed by the three isoforms of the enzymes (NO synthases; NOS). Indirect assessment of NOS gene or protein expression only provides partial information on the role of NO in health and lung disease. NO can also be measured in exhaled air by invasive or non-invasive approaches as a direct and quantitative marker of NO production in animal models. Whilst addressing the different methods of exhaled NO analysis in small animals (rats and mice), this review also focuses on the possible clinical implications, and discusses the advantages and limitations of these methods.

ZnO nanorods were prepared by different methods of MOCVD, CVD and ZnO: Al nanomaterials were synthesized by the hydrothermal method. Their structure was investigated using X-ray diffraction XRD and field emission scanning electron microscopy FESEM. The diameter of the nanorods is from 40 to 90 nm and the length is from 500 nm to 1000 nm dependent on the growth conditions. Optical properties were studied by photoluminescent with different excited of 325 and 266 nm. A dominant photoluminescent peak 380 nm was observed at room temperature. At low temperature, five peaks were observed at 3.347, 3.321, 3.301, 3.208, and 3.111 eV. The nature of luminescent peaks will be investigated. ZnO:Al nanomaterials have strong luminescent intensity in visible range dependent on Al concentration, optimal molar concentration is 7%.

Nanocrystals of ZnS:Mn2+ were prepared by chemical synthesis. The samples were characterized by scanning electron microscopy, photoluminescence, and time-resolved luminescence measurements. The emission spectra of ZnS:Mn2+ nanoparticles under 325-nm excitation consist of an intense broad band at 585 nm, ascribed to the 4T1-6A1 transition of the Mn2+ ions. No emission in the blue spectral region (about 425 nm) from the ZnS host is observed. The dependence of PL intensity on Mn2+ concentration has been investigated.

ZnO, ZnO:Al nanorods and Y(OH)3 nanotubes have been prepared by the chemical vapor deposition and liquid phase synthesis. ZnO nanorods with diameter of 50 ? 100 nm and length of 5 ?m have been obtained by the CVD method. ZnO:Al nanorods were synthesized by the hydrothermal method from ZnSO4. and Al2(SO4)3. Nanorods and nanotubes of Y(OH)3 with diameter of 200 nm and length of several micrometers were prepared by the soft template method. The crystal structure and morphology of rods and tubes were analyzed by the X-Ray diffraction and FE-SEM. The influence of fabrication conditions and Al, Eu concentration have been discussed.