Effects of dietary Nisin on growth performance, immune function, and gut health of broilers challenged by Clostridium perfringens.

Nisin (Ni) is a polypeptide bacteriocin produced by lactic streptococci (probiotics) that can inhibit the majority of gram-positive bacteria, and improve the growth performance of broilers, and exert antioxidative and anti-inflammatory properties. The present study investigated the potential preventive effect of Nisin on necrotic enteritis induced by Clostridium perfringens (Cp) challenge. A total of 288 Arbor Acres broiler chickens of 1-d-olds were allocated using 2 × 2 factorial arrangement into four groups with six replicates (12 chickens per replicate), including: (1) control group (Con, basal diet), (2) Cp challenge group (Cp, basal diet + 1.0 × 108 CFU/mL Cp), (3) Ni group (Ni, basal diet + 100 mg/kg Ni), and (4) Ni + Cp group (Ni + Cp, basal diet + 100 mg/kg Ni + 1.0 × 108 CFU/mL Cp). The results showed that Cp challenge decreased the average daily gain (ADG) of days 15 to 21 (P<0.05) and increased interleukin-6 (IL-6) content in the serum (P < 0.05), as well as a significant reduction in villus height (VH) and the ratio of VH to crypt depth (VCR) (P<0.05) and a significant increase in crypt depth (CD) of jejunum (P<0.05). Furthermore, the mRNA expressions of Occludin and Claudin-1 were downregulated (P<0.05), while the mRNA expressions of Caspase3, Caspase9, Bax, and Bax/Bcl-2 were upregulated (P<0.05) in the jejunum. However, the inclusion of dietary Ni supplementation significantly improved body weight (BW) on days 21 and 28, ADG of days 15 to 21 (P<0.05), decreased CD in the jejunum, and reduced tumor necrosis factor-α (TNF-α) content in the serum (P<0.05). Ni addition upregulated the mRNA levels of Claudin-1 expression and downregulated the mRNA expression levels of Caspase9 in the jejunum (P<0.05). Moreover, Cp challenge and Ni altered the cecal microbiota composition, which manifested that Cp challenge decreased the relative abundance of phylum Fusobacteriota and increased Shannon index (P<0.05) and the trend of phylum Proteobacteria (0.05

Necrotic enteritis (NE), a severe digestive disorder in broiler chickens caused by Clostridium perfringens (Cp), a gram-positive bacterium, is a widespread issue in the global poultry industry, leading to significant economic losses. Nisin (Ni), a polypeptide bacteriocin produced by probiotic lactic streptococci, has been found to enhance daily weight gain and feed intake, while also exhibiting inhibitory effects on gram-positive bacteria and anti-inflammatory properties. In this study, a NE infection model in broilers was established to examine the potential preventive effects of Ni. These results demonstrated that Cp challenge reduced growth performance, caused inflammatory responses and intestinal apoptosis, damaged intestinal morphology and barrier function, and was accompanied by changes in the composition of the gut microbiota. Dietary supplementation with Ni improved growth performance and protected intestine against Cp challenge-induced damage in broilers. As a result, Ni may be a potential safe and effective additive for NE prevention in broiler production.

Effects of Dietary Probiotics and Acidifiers on the Production Performance, Colostrum Components, Serum Antioxidant Activity and Hormone Levels, and Gene Expression in Mammary Tissue of Lactating Sows.

The aims of this study were to test the effects of dietary probiotics and acidifiers on the production performance, colostrum components, serum antioxidant activity and hormone levels, and gene expression in the mammary tissue of lactating sows. Four treatments were administered with six replicates to 24 lactating sows. The control group (GC) received a basal diet, while the experimental groups received a basal diet with 200 mL/d probiotics (GP), 0.5% acidifiers (GA), and 200 mL/d probiotics + 0.5% acidifiers (GM), respectively. Compared with the GC, (1) the average weight of the piglets on the 21st day of lactation in the GM was higher (p < 0.05); (2) the colostrum fat ratio increased significantly (p < 0.05); (3) the malondialdehyde levels in GP and GM were lower (p < 0.05) on the 11th day; (4) on the 1st, 11th, and 21st days, the prolactin in GP and GM increased (p < 0.05); (5) on the 21st day, the relative expression levels of the prolactin receptor and fatty acid synthase were increased (p < 0.05). In summary, the basal diet mixed with 200 mL/d probiotics + 0.5% acidifiers could improve the production performance, colostrum components, serum antioxidant activity, and hormone levels of lactating sows.

In Situ Measurement of NO, NO2, and H2O in Combustion Gases Based on Near/Mid-Infrared Laser Absorption Spectroscopy.

In this study, a strategy was developed for in situ, non-intrusive, and quantitative measurement of the oxides of nitrogen (NO and NO2) to describe emission characteristics in gas turbines. The linear calibration-free wavelength modulation spectroscopy (LCF-WMS) approach combined with the temperature profile-fitting strategy was utilized for trace NO and NO2 concentration detection with broad spectral interference from gaseous water (H2O). Transition lines near 1308 nm, 5238 nm, and 6250 nm were selected to investigate the H2O, NO, and NO2 generated from combustion. Experiments were performed under different equivalence ratios in a combustion exhaust tube, which was heated at 450-700 K, with an effective optical length of 1.57 m. Ultra-low NOx emissions were captured by optical measurements under different equivalence ratios. The mole fractions of H2O were in agreement with the theoretical values calculated using Chemkin. Herein, the uncertainty of the TDLAS measurements and the limitation of improving the relative precision are discussed in detail. The proposed strategy proved to be a promising combustion diagnostic technique for the quantitative measurement of low-absorbance trace NO and NO2 with strong H2O interference in real combustion gases.

Nitrogen-rich energetic polymer powered aluminum particles with enhanced reactivity and energy content.

Aluminum particles are of significant interest in enhancing the energy release performance of explosives. One of the major impediments to their use is that Al2O3 shell significantly decreases overall performance. To address this issue, we investigate creating aluminum particles with a glycidyl azide polymer (GAP) coating to improve their reactivity while retaining their energy content. We found that the aluminum particles were coated with a GAP layer of thickness around 8.5 nm. The coated aluminum particles were compared to non-coated powder by the corresponding reactivity parameters obtained from simultaneous differential scanning calorimetry, thermal gravimetric analysis, coupled with mass spectral and infrared spectral analyses. Besides, the comparison on the energy content was also conducted based on P-t tests and a laser-induced air shock from energetic materials (LASEM) technique. It was found that GAP shifted the oxidation onset of aluminum particles to a lower temperature by ~ 10 °C. Besides, the oxidation activation energy of aluminum particles was also reduced by ~ 15 kJ mol-1. In return, aluminum particles reduced the activation energy of the second stage decomposition of the GAP by 276 kJ mol-1. And due to the synergistic effect between aluminum and GAP, the decomposition products of GAP were prone to be oxycarbide species rather than carbonitride species. In addition, the P-t test showed the peak pressure and pressurization rate of GAP coated aluminum particles were separately 1.4 times and 1.9 times as large as those of non-coated aluminum particles. Furthermore, the LASEM experiment suggested the shock wave velocity of the GAP coated aluminum particles was larger than that of non-coated aluminum particles, and the largest velocity difference for them could be 0.6 km s-1. This study suggests after coating by GAP, the aluminum particles possess enhanced reaction performance, which shows potential application value in the fields of aluminized explosives and other energetic fields.

Instability mechanism and discharge regime diagnosis of microthrusters based on plasma properties.

In order to make it possible to control the plasma state and predict the regime transitions via coupling optical and electrical diagnosis in aerospace engineering, we have experimentally investigated the regime transitions under 0.1-15 kPa with an input discharge power of 0-25 W in a parallel-plate electrode configuration. An abnormal glow discharge (AGD), filamentary discharge (FD), and arc discharge (AD) are distinguished using the voltage-current characteristics under different gas pressures. The electron excitation temperature (Te), electron density (Ne), spatial resolutions of Te and Ne, and ionization degree are obtained via optical emission spectroscopy to reveal the transition mechanisms. Thermal instability, characterized by Te, plays a dominant role during the transition from an AGD to an FD. The conclusions are supported by analysis of ionization degree, whereas electronic instability becomes the dominant mechanism in the transition from an FD to an AD. This is related to collision kinetics because of an observed drop in Ne, which is verified by the spatial resolution as well. Moreover, planar laser-induced fluorescence provides further insight into the instantaneous location and relative number variation of Ar 1s5 metastable atoms, which agrees well with the plasma properties mentioned above. In addition, a pressure of 1 kPa with a maximum input power of 17.5 W are specified as suitable working parameters for further study when applied to microthrusters due to its higher Ne and better stability.

Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure.

A technique to improve the combustion performance of a hybrid rocket engine using a novel fuel grain structure is presented. This technique utilizes the different regression rates of acrylonitrile butadiene styrene and paraffin-based fuels, which increase the exchanges of both matter and energy by swirl flow and recirculation zones formed at the grooves between the adjacent vanes. The centrifugal casting technique is used to cast the paraffin-based fuel into an acrylonitrile butadiene styrene substrate made by three-dimensional printing. Using oxygen as the oxidizer, a series of tests were conducted to investigate the combustion performance of the novel fuel grain. In comparison to paraffin-based fuel grains, the fuel grain with a nested helical structure, which can be maintained throughout the combustion process, showed significant improvement in the regression rate and great potential in improvement of combustion efficiency.

Research on a quantitative method for three-dimensional computed tomography of chemiluminescence.

To develop a more advanced 3D computed tomography of the chemiluminescence method, the first quantitative 3D diagnosis was realized. The nonlinearity coefficient, the nonuniformity coefficient of the camera response, and various optical fiber attenuation coefficients were obtained through correction experiments. The conversion relationship between the number of photons released by the target object per unit time and the camera gray value at a specified solid angle was also calibrated. To verify the quantitative reconstruction equation, 3D reconstructions of a methane-air flat flame and a simulated phantom were performed for comparison. The method can overcome artificial distortions caused by uncorrected reconstruction.

Dynamic-force extraction for micro-propulsion testing: Theory and experimental validation.

A dynamic-force extraction, based on the least-squares method, is proposed for micro-propulsion testing. Having modeled the displacement oscillation of a micro-newton torsional pendulum, the time evolution of the dynamic force may be calculated if the stand constants are well calibrated. According to the linear characteristic of the motion equation, a reconstruction of the dynamic thrust reduces to solving linear equations. The simulation analysis shows that the error is affected by the sensor noise and the low-pass filter as well as the sampling rate. Validation experiments were performed showing that this method reconstructs the dynamic force well up to 8 Hz with an error less than 15 µN. The noise-induced error moreover varies little with frequency.

Measurement of multispecies concentration and gas temperature in an ammonium-dinitramide-based thruster by tunable diode lasers.

In this paper, quantitative experiments were made to measure the concentration of key intermediate products (CO, N2O, and NO) and the gas temperature for combustion flow based on near-infrared and mid-infrared laser absorption spectroscopy. This paper used the developed diagnostic system to study two main ignition modes of a real 1-Newton thruster based on ammonium dinitramide (ADN): steady-state firing and pulse-mode firing over a feed pressure of 5-12 bar. The steady-state firing experiments distinguished the whole process into catalytic decomposition stage and combustion stage, experimentally demonstrating the combustion kinetics mechanism of an ADN monopropellant. Experiments for pulse-mode firing showed the measured multispecies concentration and temperature were consistent with pulse trains, verifying good performance for the thruster pulse-mode firing operation. The performance of the thruster was given based on the optical measurements, and characteristic velocity for the ADN-based thruster standard operation was higher than the corresponding 1-Newton hydrazine thruster.

Three-dimensional flame measurements with large field angle.

A system for three-dimensional computed tomography of chemiluminescence was developed to measure flames over a large field angle. Nine gradient-index rods, with a 9 × 1 endoscope and only one camera are used. Its large field of view, simplicity, and low cost make it attractive for inner flow field diagnostics. To study the bokeh effect caused by the imaging system on reconstruction solutions, fluorescent beads were used to determine the blurring function. Experiments using a steady diffusion flame were conducted to validate the system. Three models, namely the clear-imaging, out-of-focus imaging, and deconvolution models, were utilized. Taking the bokeh effect into account, the results suggest that based on run-times the deconvolution model provides the best reconstruction accuracy without increasing computational time.

Growth inhibition and apoptosis of human B-cell lymphoma in vitro and in vivo by Bcl-2 short hairpin RNA.

Bcl-2 is overexpressed in various types of human tumors, including Burkitt's lymphoma, and it is involved in tumorigenesis and chemoresistance, therefore, it is regarded as a potential target of gene therapy. In this study, RNA interference using short hairpin RNA (shRNA)-mediated RNA interference was introduced into Burkitt's lymphoma Raji cells to validate its effects on Bcl-2 expression and cell proliferation in vitro and in vivo. We constructed two types of Bcl-2 shRNA plasmid (pGenesil-1-Bcl-2-1 and pGenesil-1-Bcl-2-2) and negative control shRNA plasmid (pGenesil-1-NC) and stably transfected them into Raji cells. The expression levels of Bcl-2 mRNA and protein were assayed by RT-PCR, flow cytometry and western blotting. Cell proliferation was determined by cell count assay. The antitumor activities and apoptosis of the two types of Bcl-2 shRNA plasmid were evaluated in BALB/c nude mice bearing Burkitt's lymphoma inoculated with Raji cells. The results showed that the expression levels of Bcl-2 mRNA and protein decreased, compared with either the pGenecil-1-NC or the untransfected cell group (P<0.05). The cell proliferation assay showed that Bcl-2 shRNA significantly inhibited the growth of Raji cells (P<0.01). Furthermore, the tumor growth of the Bcl-2 shRNA cell group was dramatically lower and smaller than that of the negative control or untransfected cell group (P<0.01). Bcl-2 protein expression in the untransfected and the pGenesil-1-NC group were markedly higher than that of the pGenesil-1-Bcl-2-1 and the pGenesil-1-Bcl-2 group by immunohistochemistry (both P<0.01) and the results using transmission electron microscopy showed that Bcl-2 shRNA significantly induced Raji cell apoptosis. Additionally, the inhibition effect of pGenesil-1-Bcl-2-1 was better than that of pGenesil-1-Bcl-2-2. It has been suggested that vector-based Bcl-2 shRNA could effectively reduce the expression of Bcl-2 and induce apoptosis and growth inhibition of Burkitt's lymphoma Raji cells. Vector-based Bcl-2 shRNA could be a potential gene therapeutic strategy against human Burkitt's lymphoma.

Uncertainty in velocity measurement based on diode-laser absorption in nonuniform flows.

This work investigates the error caused by nonuniformities along the line-of-sight in velocity measurement using tunable diode-laser absorption spectroscopy (TDLAS). Past work has demonstrated TDLAS as an attractive diagnostic technique for measuring velocity, which is inferred from the Doppler shift of two absorption features using two crossing laser beams. However, because TDLAS is line-of-sight in nature, the obtained velocity is a spatially averaged value along the probing laser beams. As a result, nonuniformities in the flow can cause uncertainty in the velocity measurement. Therefore, it is the goal of this work to quantify the uncertainty caused by various nonuniformities typically encountered in practice, including boundary layer effects, the divergence/convergence of the flow, and the methods used to fit the Doppler shift. Systematic analyses are performed to quantify the uncertainty under various conditions, and case studies are reported to illustrate the usefulness of such analysis in interpreting experimental data obtained from a scramjet facility. We expect this work to be valuable for the design and optimization of TDLAS-based velocimetry, and also for the quantitative interpretation of the measurements.

Double-end-pumped Nd:YVO4 slab laser at 1064 nm.

We demonstrate a high-power laser diode stacks double-end-pumped Nd:YVO4 1064 nm slab laser with a folded stable-unstable hybrid resonator. An output power of 220 W was obtained at the pump power of 490 W with optical conversion efficiency of 44.9%. At the output power of 202 W, the M2 factors in the unstable direction and in the stable direction were 1.7 and 2.3, respectively.

Simultaneous measurements of multiple flow parameters for scramjet characterization using tunable diode-laser sensors.

This paper reports the simultaneous measurements of multiple flow parameters in a scramjet facility operating at a nominal Mach number of 2.5 using a sensing system based on tunable diode-laser absorption spectroscopy (TDLAS). The TDLAS system measures velocity, temperature, and water vapor partial pressure at three different locations of the scramjet: the inlet, the combustion region near the flame stabilization cavity, and the exit of the combustor. These measurements enable the determination of the variation of the Mach number and the combustion mode in the scramjet engine, which are critical for evaluating the combustion efficiency and optimizing engine performance. The results obtained in this work clearly demonstrated the applicability of TDLAS sensors in harsh and high-speed environments. The TDLAS system, due to its unique virtues, is expected to play an important role in the development of scramjet engines.

Near-diffraction-limited,35.4 W laser-diode end-pumped Nd:YVO4 slab laser operating at 1342 nm.

A diode stack end-pumped Nd:YVO4 slab laser at 1342 nm with near-diffraction-limited beam quality by using a hybrid resonator was presented. At a pump power of 139.5 W, laser power of 35.4 W was obtained with a conversion efficiency of 25.4% of the laser diode to laser output. The beam quality M2 factors were measured to be 1.2 in the unstable direction and 1.3 in the stable direction at the output power of 29 W.