High Injection Levels Research Articles

Harnessing Persistent Photocurrent in a 2D Semiconductor-Polymer Hybrid Structure: Electron Trapping and Fermi Level Modulation for Optoelectronic Memory.

Recently, 2D semiconductor-based optoelectronic memory has been explored to overcome the limitations of conventional von Neumann architectures by integrating optical sensing and data storage into one device. Persistent photocurrent (PPC), essential for optoelectronic memory, originates from charge carrier trapping according to the Shockley-Read-Hall (SRH) model in 2D semiconductors. The quasi-Fermi level position influences the activation of charge-trapping sites. However, the correlation between quasi-Fermi level modulations and PPC in 2D semiconductors has not been extensively studied. In this study, we demonstrate optoelectronic memory based on a 2D semiconductor-polymer hybrid structure and confirm that the underlying mechanism is charge trapping, as the SRH model explains. Under light illumination, electrons transfer from polyvinylpyrrolidone to p-type tungsten diselenide, resulting in high-level injection and majority carrier-type transitions. The quasi-Fermi level shifts upward with increasing temperature, improving PPC and enabling optoelectronic memory at 433 K. Our findings offer valuable insights into optimizing 2D semiconductor-based optoelectronic memory.

Analytical models of the electric field and carrier transit time in the base of bipolar junction transistors

The conventional theory of the bipolar junction transistor (BJT) does not clarify the electric field and its effect on the carrier transit in the uniformly doped base region, although the electric field is considered to be a second-order effect at high-level injection. In this study, analytical models of the carrier distribution, electric field, and carrier transit time in the base region are developed without making additional assumptions. It is found that the electric field may change direction, from forward to reverse, as long as the injection level reaches a criterion, affecting the carrier transport behavior. The models are based on the renovated p–n junction theory, provide insight into the carrier transit and are able to cover all levels of injection without the need to handle the low- and high-level injection separately. These models hold significance in retrieving the theoretical integrity of bipolar junction devices, and can be useful for further investigation in structure design, capacitance control, and AC performance optimization of the p–n junction-based device.

Calculation of GaInSb PNP lateral HBT for complementary bipolar logic technology

In this study, the power consumption and speed of a GaInSb PNP lateral heterojunction bipolar transistor were estimated for applications in complementary bipolar logic circuits. At the supply voltage of 250 mV, the current gain is over 1000, on/off power consumption ratio is approximately 180, and delay time is 2.6 ps. However, the characteristics degrade rapidly at voltages greater than 300 mV, owing to deep saturation and high-level injection.

Optical Absorption, Photocarrier Recombination Dynamics and Terahertz Dielectric Properties of Electron-Irradiated GaSe Crystals

Optical absorption spectra of 9 MeV electron-irradiated GaSe crystals were studied. Two absorption bands with the low-photon-energy threshold at 1.35 and 1.73 eV (T = 300 K) appeared in the transparency region of GaSe after the high-energy-electron irradiation. The observed absorption bands were attributed to the defect states induced by Ga vacancies in two charge states, having the energy positions at 0.23 and 0.61 eV above the valence band maximum at T = 300 K. The optical pump-terahertz probe technique (OPTP) was employed to study the dark and photoexcited terahertz conductivity and charge carrier recombination dynamics at two-photon excitation of as-grown and 9 MeV electron-irradiated GaSe crystals. The measured values of the differential terahertz transmission at a specified photoexcitation condition were used to extract the terahertz charge carrier mobilities. The determined terahertz charge carrier mobility values were ~46 cm2/V·s and ~14 cm2/V·s for as-grown and heavily electron-irradiated GaSe crystals, respectively. These are quite close to the values determined from the Lorentz–Drude–Smith fitting of the measured dielectric constant spectra. The photo-injection-level-dependent charge carrier lifetimes were determined from the measured OPTP data, bearing in mind the model injection-level dependencies of the recombination rates governed by interband and trap-assisted Auger recombination, bulk and surface Shockley–Read–Hall (SRH) recombination and interband radiative transitions in the limit of a high injection level. It was found that GaSe possesses a long charge carrier lifetime (a~1.9 × 10−6 ps−1, b~2.7 × 10−21 cm3ps−1 and c~1.3 × 10−37 cm6ps−1), i.e., τ~0.53 μs in the limit of a relatively low injection, when the contribution from SRH recombination is dominant. The electron irradiation of as-grown GaSe crystals reduced the charge carrier lifetime at a high injection level due to Auger recombination through radiation-induced defects. It was found that the terahertz spectra of the dielectric constants of as-grown and electron-irradiated GaSe crystals can be fitted with acceptable accuracy using the Lorentz model with the Drude–Smith term accounting for the free-carrier conductivity.

PSVI-15 Effect of Split Iron Injection to Sucking Pigs on Growth Performance and Hematological Variables in Pre- and Post-Weaning Periods

Abstract The aim of this study was to evaluate the effects of split iron injection to suckling pigs on growth performance and hematological variables in pre- and postweaning periods. A total of 23 piglets (initial body weight: 2.19 ± 0.15 kg) were allotted into 3 treatments within litter based on body weight and sex. Treatments were: 1) Iron100: 100 mg iron at d 0 of experiment (d 3-4 of age) + no additional iron injection - control), 2) Iron100/100: 100 mg iron at d 0 of experiment + 100 mg iron injection at d 9 of experiment (d 14 before weaning), and 3) Iron200: 200 mg iron at d 0 of experiment + no additional iron injection. The pigs were housed by litter in the suckling and nursery periods with a common corn-soybean meal-based diet during the entire nursery period. Body weight, hemoglobin concentrations and hematocrit were measured at d 0 (initial), 9 (second dose for the Iron100/100 treatment), 16, 23 (weaning), and 36 of experiment. Body weight and average daily gain did not differ among treatments before weaning whereas the Iron100/100 treatment had greater body weight than the Iron100 treatment at d 36 of experiment (P < 0.05; 10.17, 12.55, and 11.45 kg for the Iron100, Iron100/100 and Iron200 treatments, respectively) and the Iron100/100 treatment had greater average daily gain in d 23-36 of experiment than the Iron100 (P< 0.05) and Iron200 (P = 0.08) treatments (0.112, 0.238, and 0.156 kg/d for Iron100, Iron100/100 and Iron200 treatments, respectively). At d 9 of experiment, the Iron200 treatment had greater hematocrit than the Iron100 and Iron100/100 treatments (P < 0.05; 30.35, 29.88, and 33.85% for Iron100, Iron100/100, and Iron200 treatments, respectively) and tended to have greater hemoglobin levels than the Iron100/100 treatment (P = 0.06). At d 16 and 23 (weaning) of experiment, hemoglobin concentrations and hematocrit were greater in the Iron100/100 and Iron200 treatments (P < 0.05) than the Iron100 treatment (9.39, 11.66, and 11.41 g/dL for Iron100, Iron100/100, and Iron200 treatments, respectively for hemoglobin concentrations at d 23 of experiment). At d 36 of experiment, hemoglobin concentrations tended to be greater in the Iron200 treatment than the Iron100 treatment (P = 0.09) and hematocrit were greater in the Iron100/100 (P = 0.10) and Iron200 (P < 0.05) treatments than the Iron100 treatment (29.73, 31.56, and 33.54% for the Iron100, Iron100/100, and Iron200 treatments, respectively) with greater values (P = 0.10) in the Iron200 treatment than the Iron100/100 treatment. In conclusion, the piglets that received low level of iron at birth had decreased growth rate and hematological variable values while split iron injection could increase growth rate after weaning even though it maintained postweaning hematocrit slightly less than high level of iron injection at birth.

Improvement of Power and Efficiency of High-Mesa Semi-Insulating InP: Fe Buried Heterostructure Lasers with Wide Bandgap Layers

High-mesa semi-insulating buried heterostructure (SIBH) lasers with InP: Fe have great potential in high-speed and high-power scenarios, but the leakage current problem under high current injections has always limited their application. In order to solve the issue of low output power and low efficiency for high-mesa SIBH lasers, the mechanism of leakage current generation in InP-based semi-insulating (SI) layers at high injection levels was analyzed through numerical simulation. The deterioration of the device performance is due to the hole current-induced electron leakage current, which results from the reduction of the potential barrier and Fe-Zn interdiffusion. Thus, lasers with wide bandgap layers of InAlAs and ZnCdSe were employed for current blocking, the power and wall-plug efficiency of which were improved by more than 36% and 5%, respectively. For the first time, a SIBH laser based on lattice-matched ZnCdSe barrier layers is proposed, which shows good output performance and high reliability. The introduction of the wide bandgap layer in the SIBH structure establishes potential barriers to confine both carrier leakages at high injection levels, which realizes the high-power and high-efficiency operation of the laser.

Distributed Optimal Power Flow in Unbalanced Distribution Grids With Non-Ideal Communication

The use of distributed optimization for solving optimal power flow (OPF) problems in distribution networks is increasing as the number of controllable devices and the span of service areas increase. However, the performance of the distributed optimization algorithm largely depends on the availability and quality of communication links between the computing entities. In this paper, we evaluate the performance of the alternating direction method of multipliers (ADMM) for solving the OPF problem for volt-VAr optimization (VVO) under non-ideal communication. The overall problem is formulated by considering the unbalanced operation of multi-phase distribution networks. The algorithm's performance is first analyzed, assuming there is an ideal communication between computing entities, which serves as a benchmark for further analysis. Then, two non-ideal communication models, namely (1) sporadic communication failure and (2) communication under a noisy transmission, are applied to the information exchange architecture of the ADMM. Extensive numerical experiments are conducted with two test systems, the IEEE 123-bus feeder and a 2522-bus network scaled down from the IEEE 8500-bus system; these are used to evaluate the performance of the algorithm. The results indicate that the ADMM-based distributed VVO algorithm has deteriorated performance under high levels of communication failure and high levels of noise injection. Additionally, although the centralized-VVO counterpart has some computational superiority when the overall problem is convex and no communication impairments exist, the distributed-VVO has superior immunized solution performance under realistic communication constraints.

Enhanced quantum yield at high exciton density in monolayer transition metal dichalcogenides

Monolayer transition metal dichalcogenides are a class of atomically thin semiconductors that have a direct bandgap, making them promising candidates for optoelectronic and photonic devices. However, the low quantum yield at high charge injection levels significantly limits their applicability in optoelectronic devices that function under high current densities, such as light-emitting diodes and lasers. To address this issue, we demonstrate the use of hexagonal boron nitride encapsulation as a means of tuning the photoluminescence properties in monolayer transition metal dichalcogenides. Our results show a several-fold enhancement in the photoluminescence quantum yield at high exciton densities. This improvement is attributed to the suppressed exciton–exciton annihilation, which is supported by experimental time-resolved photoluminescence spectra and theoretical analysis. Our findings provide a simple and effective method for achieving highly efficient optoelectronic devices based on monolayer transition metal dichalcogenides.

An avalanche-and-surge robust ultrawide-bandgap heterojunction for power electronics

Avalanche and surge robustness involve fundamental carrier dynamics under high electric field and current density. They are also prerequisites of any power device to survive common overvoltage and overcurrent stresses in power electronics applications such as electric vehicles, electricity grids, and renewable energy processing. Despite tremendous efforts to develop the next-generation power devices using emerging ultra-wide bandgap semiconductors, the lack of effective bipolar doping has been a daunting obstacle for achieving the necessary robustness in these devices. Here we report avalanche and surge robustness in a heterojunction formed between the ultra-wide bandgap n-type gallium oxide and the wide-bandgap p-type nickel oxide. Under 1500 V reverse bias, impact ionization initiates in gallium oxide, and the staggered band alignment favors efficient hole removal, enabling a high avalanche current over 50 A. Under forward bias, bipolar conductivity modulation enables the junction to survive over 50 A surge current. Moreover, the asymmetric carrier lifetime makes the high-level carrier injection dominant in nickel oxide, enabling a fast reverse recovery within 15 ns. This heterojunction breaks the fundamental trade-off between robustness and switching speed in conventional homojunctions and removes a key hurdle to advance ultra-wide bandgap semiconductor devices for power industrial applications.

Fault Injection for TensorFlow Applications

As machine learning (ML) has seen increasing adoption in safety-critical domains (e.g., autonomous vehicles), the reliability of ML systems has also grown in importance. While prior studies have proposed techniques to enable efficient error-resilience (e.g., selective instruction duplication), a fundamental requirement for realizing these techniques is a detailed understanding of the application's resilience. In this work, we present TensorFI 1 and TensorFI 2, high-level fault injection (FI) frameworks for TensorFlow-based applications. TensorFI 1 and 2 are able to inject both hardware and software faults in any general TensorFlow 1 and 2 program respectively. Both are configurable FI tools that are flexible, easy to use, and portable. They can be integrated into existing TensorFlow programs to assess their resilience for different fault types (e.g., bit-flips in particular operations or layers). We use the TensorFI 1 and TensorFI 2 to evaluate the resilience of 11 and 10 ML programs written in TensorFlow, including DNNs used in the autonomous vehicle domain. The results give us insights into why some of the models are more resilient. We also measure the performance overheads of the two injectors, and present 4 case studies, two for each tool, to demonstrate their utility.

Impedance spectroscopic analysis of long-lifetime blue fluorescent organic light emitting diode

Hole and electron carrier transport dynamics of blue fluorescent organic light emitting diodes (OLEDs) were analyzed by impedance spectroscopic technique, and the relation between lifetimes and the dynamics was investigated. The OLEDs with different hole carrier transport property were fabricated by optimizing thickness of electron-blocking layer (EBL), while the electron transport level was fixed. The EBL was arranged between emission and hole transport layers (EML and HTL), and highest occupied molecular orbital level of the EBL was between those of EML and HTL. Both Cole-Cole plot and Bode-plot of imaginary part indicated that relaxation rate of hole carrier transport for the OLED with thin EBL was larger than that for the OLED with thick EBL. The relaxation rates of electron carrier transport were the same level with each other. The lifetime of the OLED with the thin EBL was longer than that of the OLED with the thick EBL. The results give us estimation that the hole carrier injection into the EML is increased for the OLED with relatively thin EBL, inducing long lifetime due to high level of hole injection into the EML even the occurrence of electron leakage from the EML to EBL.

Enhanced Performance of N-Polar AlGaN-Based Ultraviolet Light-Emitting Diodes With Lattice- Matched AlInGaN Insertion in n-AlGaN Layer

AlGaN-based ultraviolet-A light-emitting diodes (UVA LEDs) inevitably suffer from current crowding effects at high injection levels due to their lateral device structure, resulting in non-uniform light emission and device overheating. In N-polar UV LEDs, the problem is further exacerbated by increased hole injection efficiency, leading to current crowding and aggravated hole leakage, which limits the device performance. An n-AlGaN/AlInGaN/AlGaN structure is adopted in this study, through modulation of the Al and In compositions in the AlInGaN quaternary alloy, lattice matching and greater bandgap of AlInGaN to AlGaN template is designed. The numerical results prove that the n-AlGaN/AlInGaN/AlGaN structure can promote current spreading and thus mitigate hole leakage, resulting in the significantly enhanced performance of N-polar UVA LEDs. Furthermore, the use of lattice-matched AlInGaN layers in practical epitaxy is feasible, which can avoid the defect introduction resulting from the lattice mismatch.

An Uncalibrated Image-Based Visual Servo Strategy for Robust Navigation in Autonomous Intravitreal Injection

Autonomous intravitreal injection in ophthalmology is a challenging surgical task as accurate depth measurement is difficult due to the individual differences in the patient’s eye and the intricate light reflection or refraction of the eyeball, often requiring the surgeon to first preposition the end-effector accurately. Image-based visual servo (IBVS) control does not rely on depth information, exhibiting potential for addressing the issues mentioned above. Here we describe an enhanced IBVS strategy to achieve high performance and robust autonomous injection navigation. The radial basis function (RBF) kernel with strong learning capability and fast convergence is used to globally map the uncertain nonlinear strong coupling relationship in complex uncalibrated IBVS control. The Siamese neural network (SNN) is then used to compare and analyze the characteristic differences between the current and target poses, thus making an approximation of the mapping relationships between the image feature changes and the end-effector motion. Finally, a robust sliding mode controller (SMC) based on min–max robust optimization is designed to implement effective surgical navigation. Data from the simulation and the physical model experiments indicate that the maximum localization and attitude errors of the proposed method are 0.4 mm and 0.18°, exhibiting desirable accuracy with the actual surgery and robustness to disturbances. These results demonstrate that the enhanced strategy can provide a promising approach that can achieve a high level of autonomous intravitreal injection without a surgeon.

Evaluation of the accumulation of the iodinated contrast agents diatrizoic acid and iohexol in Dreissena polymorpha mollusks

Mollusks are very sensitive to aquatic environmental alterations and then, are important bio-indicators for monitoring the contamination of water bodies. Iodinated X-ray contrast media (ICMs) are ubiquitously present in the aquatic environment, primarily due to their high consumption for diagnosis purposes, high injection levels, low biodegradability, and low removal rates by wastewater treatment plants. Although these compounds are assumed to be of low toxicity, aquatic organisms are continuously exposed to these agents, which may result in adverse effects as ICMs can act as iodine source and disrupt the endocrine system. Thus, the evaluation of their environmental risk, especially on aquatic fauna is of great interest.To this end, we first compared the accumulation behavior, based on iodine analysis, of two ICM exhibiting different osmolality, diatrizoic acid and iohexol in Dreissena polymorpha bivalves exposed under laboratory conditions at concentrations of 0, 100, and 1000 μg/L during 4 and 7 days. This study was the first to provide information on iodine concentration in whole soft tissues and several organs in control zebra mussels. Moreover, it showed, after exposure, an increase of iodine content mainly in the digestive glands, followed by gills and gonads, highlighting that ICMs actually enter the organisms. Thus, bioaccumulation of ICMs studies were then performed, by liquid chromatography coupled to tandem mass spectrometry, on entire mollusks and digestive glands of organisms exposed at 0, 10, 100, and 1000 μg/L of both ICMs during 21 days, followed by 4 days of depuration. These first data on ICMs concentrations in zebra mussels, showed a clear accumulation of ICMs in mussels as a function of relative exposure level, as well as a rapid depuration. Osmolality did not seem to have a significant impact on the accumulation level, but a slight difference was observed on the accumulation pattern between both ICMs.

Effect of Additional Iron Injection to Suckling Pigs on Hematocrit Level during the Suckling Period.

Two experiments were conducted to evaluate the effects of additional iron injection to suckling piglets on hematocrit level during the suckling period. In Experiment 1, a total of 24 piglets were allotted into 3 treatments within litter based on body weight and sex at d 1 of age. Treatments were: (1) Control: a 200 mg iron-dextran intramuscular injection only at d 0 of experiment (d 1 of age), (2) Iron100: intramuscular iron-dextran injections at d 0 (200 mg iron) and 15 (11 d before weaning) of experiment (100 mg iron), and (3) Iron200: intramuscular iron-dextran injections at d 0 (200 mg iron) and 15 of experiment (200 mg iron). In Experiment 2, a total of 20 piglets were allotted into 2 treatments within litter based on body weight and sex at d 1 to 2 of age. Treatments were: (1) Iron100b: 100 mg iron-dextran intramuscular injection at d 0 of experiment (d 1 to 2 of age), and (2) Iron200b: 200 mg iron-dextran intramuscular injection at d 0 of experiment. An additional 200 mg iron-dextran was injected to all piglets intramuscularly at d 14 of experiment (11 d before weaning). In Experiment 1, there was no difference in hematocrit levels among treatments at d 15 of experiment. Both iron treatments had greater hematocrit levels than the Control treatment at d 22 and 26 of experiment (p < 0.05). The Iron200 treatment had greater hematocrit level at d 26 of experiment (p < 0.05) and tended to have a greater increase of hematocrit levels in d 22 to 26 of experiment (p = 0.09) than the Iron100 treatment. In Experiment 2, the Iron200b treatment had greater hematocrit levels than the Iron100b treatment in d 14 and 25 (p < 0.05) of experiment. Hematocrit level changes tended to be greater in the Iron200b treatment in d 0 to 14 (p = 0.08) of experiment but lower in d 14 to 25 (p < 0.05) of experiment than the Iron100b treatment. The additional iron injection to suckling piglets increased hematocrit levels with greater values at weaning in the higher injection level whereas the increase was greater when the hematocrit level was low at the time of additional injection.

Behavioral patterns of people who use synthetic psychostimulants: Results of a qualitative study in St. Petersburg, Russia.

Russia, like many other places, is currently experiencing a proliferation of new psychoactive substances, many of which are psychostimulants. In St. Petersburg, these appear to be mostly congeners of cathinone. We sought to obtain qualitative data to better understand the impact on the health and behaviors of people who use drugs (PWUD) by recruiting individuals who reported recent use of psychostimulants. In-depth qualitative data on current drug use and its effects were collected through thirty interviews (n=30) and two focus groups (n=10: five male, five female). The interviews and focus groups also provided data on the social contexts of drug use including sexual behaviors and associated medical issues. Secondary data about online drug purchases were obtained from a source that accesses and analyzes darknet purchases. Qualitative data were initially coded using a priori codes developed on the basis of the interview guide, and then data were coded again inductively based on emergent findings from the data. Thematic analysis was carried out using OpenCode 4.0 qualitative data analysis software. Thematic analysis of the interviews and focus groups identified distinct differences in behavior patterns between older, more experienced PWUD and a "new generation" of PWUD. Routes of initiation of drug use and sexual behaviors associated with drug use differed, but both groups reported high levels of unsafe injection and sexual behaviors. In interpreting the texts and purchasing data, we have attempted to anticipate how the drug use patterns can influence HIV transmission. The emergence of a new class of psychostimulant drugs presents new threats to the health of drug users and new opportunities to intervene to reduce those risks. The information obtained may assist HIV/AIDS prevention specialists and drug user support groups in their efforts to decrease unsafe drug use and sexual behaviors.

CAFI: A Configurable location-Aware Fault Injection technique for software reliability assessment against soft errors

The rapid development of processor manufacturing technologies has encouraged most designers to highlight the processors' resilience to errors. Regarding embedded systems in harsh environments, temporary faults, such as single-event upsets (SEUs) or single-event multiple upsets (SEMUs), induced by radiation effects on a memory cell or a combinational logic circuit, can cause perturbations in the system's behavior, which in turn can cause catastrophic consequences. In this context, Fault Injection (FI) has been successfully applied as a mature method to assess reliability against faults and reveal the system's deficiencies to be protected cost-effectively. Although high-level software FI techniques are less accurate, the high accuracy of fault injection at a low level usually comes at the expense of desirable characteristics related to portability, flexibility, and intrusiveness. Hence, this paper proposes a Configurable location-Aware Fault Injection (CAFI) technique. CAFI is a software-based technique that facilitates emulating different kinds of transient hardware faults, e.g., SEUs and SEMUs, at the software level. Therefore, it supports flexibility in conducting reliability assessment studies with varying fault models. It operates at the binary code level and exploits a timing-based mechanism to inject faults at run-time in a negligible intrusive manner. CAFI can inject faults at different granularity levels to maximize fault activation. In detail, a fine-grained into a specific instruction field and a coarse-grained into the whole system's software. CAFI requires negligible modifications to the target software under test and allows it to run at near-native speed. The effectiveness of CAFI is evaluated by conducting many fault injection experiments applying to different real-world benchmark programs. Moreover, the accuracy of CAFI is quantified with respect to high-level software fault injection. For this aim, a practical prototype of CAFI is implemented on the x86 architecture employing an Intel core i7 processor with 16GB RAM. Based on a total of 108,000 fault injection experiments, the rate of program crashes caused by CAFI is slightly more than 18% higher than that caused by high-level software fault injection. On the other hand, there are no significant differences between the silent data corruptions (SDCs), results obtained by CAFI, and high-level software fault injections, making CAFI applicable for studying crash- and SDC-causing errors.

Extreme Double/Triple Asymmetric Epitaxial Structure Based Diode Lasers for High Powers and High Efficiencies

In edge-emitting high power laser diodes, the longitudinal spatial hole burning (LSHB) effect induced by the inhomogeneous photon and carrier distributions and the non-linear process, two-photon absorption (TPA), are demonstrated to the key causes of power saturation at the high injection level even in the absence of thermal roll-over. Laser diodes based on extreme, double/triple asymmetric (EDAS/ETAS) epitaxial structures show great potentials in high-power and high-efficiency applications owing to the reduced series resistance, low optical loss, and suppressed power saturation. In this paper, a novel semi-analytical calculation method is proposed to systematically analyze the impact of LSHB and TPA effects on the output characteristics of EDAS/ETAS-based broad area lasers (BALs). By leveraging the feature that it is flexible to adjust the confinement factor of ETAS epitaxial structure without compromising the internal loss and resistance level, the laser parameters are first optimized to minimize power saturation of ETAS-based BALs under pulsed and Continuous Wave (CW) operation.

Effects of the In Ovo Injection of L-Ascorbic Acid on Broiler Hatching Performance.

Simple SummaryPrevious studies have shown positive effects of the use of supplementary L-ascorbic acid (L-AA) to mitigate various stressors such as heat and ammonia exposure in the broiler industry. The aim of the current study was to determine the effects of L-AA administrated by in ovo injection on various hatch variables and the embryonic serum L-AA concentrations of Ross 708 broilers. At 18 days of incubation (doi), the following four treatment groups: non-injected control, saline-injected control, and saline containing either 12 or 25 mg of L-AA were administrated. An automated multi-egg injector accurately delivered 100 μL solution volumes into the amnion. The in ovo injection of high levels of L-AA (12 and 25 mg) did not affect hatchability, but 12 mg of L-AA in saline and saline alone resulted in a reduction in embryonic mortality. Additionally, serum L-AA did not differ between the in ovo injected treatments at any time period; however, the serum L-AA concentration was numerically higher in males as compared to female hatchlings. In conclusion, the automated in ovo injection of high levels of L-AA may not be detrimental to hatchling quality but may promote embryonic livability.Effects of the in ovo injection of various concentrations of L-ascorbic acid (L-AA) on the hatchability and retention levels of L-AA in the serum of broiler embryos were investigated. A total of 960 Ross 708 broilers hatching eggs were randomly divided into four treatment groups: non-injected control, saline-injected control, and saline containing either 12 or 25 mg of L-AA. At 18 days of incubation (doi), injected eggs received a 100 μL volume of sterile saline (0.85%) alone or containing one of the two L-AA levels. Percentage egg weight loss was also determined from 0 to 12 and 12 to 18 doi. Hatch residue analysis was conducted after candling to determine the staging of embryo mortality. At approximately 21 doi, hatchability of live embryonated eggs (HI) and hatchling body weight (BW) were determined. Blood samples were taken at 6 and 24 h after L-AA in ovo injection to determine serum L-AA concentrations. Serum L-AA concentrations, HI, and hatchling BW did not differ among all treatment groups. However, chicks in the non-injected group had a higher (p = 0.05) embryonic mortality at hatch in comparison to those in the 12 mg of L-AA in saline and saline alone treatment groups. These results suggest that the in ovo injection of high levels of L-AA (12 and 25 mg) does not negatively affect HI or serum concentrations of L-AA but has the potential to promote embryonic livability. Further research is needed to determine the retention time of L-AA in the other tissues of broilers, including the cornea of the eye, in response to different levels of supplemental L-AA.

Impact of Carriers Injection Level on Transients of Discrete and Paralleled Silicon and 4H-SiC NPN BJTs

The 4H-SiC vertical NPN BJTs are attractive power devices with potentials to be used as high power switching devices with high voltage ratings in range of 1.7 kV and high operating temperatures. In this paper, the advantages of the 4H-SiC NPN BJTs in terms of switching transients and current gain over their silicon counterparts is illustrated by means of extensive experimental measurements and modelling, including investigation of high level injection, as a common phenomenon in bipolar devices that influences the switching rates and DC current gain. The two device types have been tested at 800 V with maximum temperature of 175 °C and maximum collector current of 8 A. The turn-ON and turn-OFF transition in Silicon BJT is seen to be much slower than that of the SiC BJT while the transient duration will increase with increasing temperature and decreases with larger collector currents. The common-emitter current gain of SiC BJT is also found to be much higher than silicon counterparts, increasing with temperature in low injection levels but decreasing in higher injection levels in both devices. The rate of increase of current gain slows down toward stability as the collector current increases, known as the high-level injection. Current sharing imbalance among parallel connected devices is also investigated, which are shown to be evidently dependant on temperature and base resistance in Silicon BJT, while the current collapse in also seen in SiC BJT at high injection levels with high base resistance. The turn-OFF delay is seen to be temperature dependant in single and paralleled Silicon BJTs while almost non-existent in SiC device.