Mechanism underlying 2n male and female gamete formation in lemon via cytological and molecular marker analysis

Kai‑Dong Xie,Qiang‑Ming Xia,Jun Peng,Xiao‑Meng Wu,Zong‑Zhou Xie,Chun‑Li Chen,Wen‑Wu Guo 한국식물생명공학회 2019 Plant biotechnology reports Vol.13 No.2

The unreduced (2n) gametes have long been used in triploid breeding of citrus. In lemon, the previously reported mechanisms for 2n megagametophyte formation were controversial, whereas that for 2n pollen production is still unknown. Herein, the frequency of and mechanism underlying 2n megagametophyte and 2n pollen formation in ‘Eureka’ lemon were investigated based on cytological observation and genotyping of the triploid hybrids between ‘Eureka’ lemon and ‘Early gold’ sweet orange. As a result, 4.79% of the viable pollens of ‘Eureka’ lemon were identified as the 2n pollen with a larger diameter (70.16 ± 3.92 μm). The 2n pollen might be resulted from the formation of parallel spindles at meiosis stage II. Among the 204 plantlets regenerated from embryo rescue following the sexual cross, 12 were triploids as identified by flow cytometry. According to the analysis of heterozygosity transmission using 13 pericentromeric single nucleotide polymorphism (SNP) markers and 20 randomly distributed simple sequence repeat (SSR) markers, 11 triploids were identified to be originated from the fertilization of 2n megagametophytes of ‘Eureka’ lemon, with a frequency of 5.39%. Among them, nine 2n megagametophytes were supposed to be arisen from the second division restitution (SDR), whereas the other two were from postmeiotic genome doubling (PMD). These results to understand the mechanism underlying 2n gamete formation in lemon are valuable for its efficient polyploid breeding.

Study of Time-Dependent Characteristics of a Syllectogram in the Presence of Aggregation Inhibition

Peng Kai Ong,임도형,Swati Jain,남궁범석,김상호,전경진,추준욱 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

Red blood cell aggregation is an important risk indicator of cardiovascular diseases, which can be quantified by dynamical parameters derived from a time-dependent light transmission profile (syllectogram). This study tests the hypothesis that inhibitory factors on the aggregation process of the blood could greatly alter the dynamical information provided by the syllectogram and highlights the possible limitations in utilizing time-dependent photometric methods for quantifying aggregation. The concept of AIwin (aggregation index) that has been used in conventional aggregometers to determine the extent of aggregation within a 12-s standard time period was distinguished from AI (aggregation index) derived from the aggregating phase of syllectogram. Apparent time delays in shape recovery and aggregating phases were observed at high levels of aggregation inhibition (high medium viscosity) which accounted for the discrepancy between AI and AIwin. In the presence of a small shear (3 s-1), this discrepancy diminished. Fractal analysis was used to validate the aggregation results obtained from the syllectogram. AI was found to better depict the extent of aggregation compared to AIwin.

Effects of Octacosanol Extracted from Rice Bran on the Laying Performance, Egg Quality and Blood Metabolites of Laying Hens

Peng, Kai,Long, Lei,Wang, Yuxi,Wang, Shunxi Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.10

A 42-d study with 384 Hy-line brown laying hens was conducted to assess the effects of dietary octacosanol supplementation on laying performance, egg quality and blood metabolites of laying hens. Hens were randomly allocated into 4 dietary groups of 8 cages each, which were fed basal diet supplemented with 0 (Control), 9 (OCT9), 18 (OCT18), and 27 (OCT27) mg/kg diet of octacosanol isolated from rice bran, respectively. The experiment was conducted in an environmental controlled house and hens were fed twice daily for ad libitum intake. Laying performance was determined over the 42-d period, and egg quality as well as blood metabolites were estimated on d 21 and d 42. Diets in OCT18 and OCT27 increased (p<0.05) laying rate, egg weight, egg mass, egg albumen height, Haugh unit and eggshell strength on d 42, but decreased (p<0.05) feed conversion rate and levels of total cholesterol, triglyceride and low density lipoprotein cholesterol in the serum as compared to those of Control. Feed intake, yolk color, yolk diameter, eggshell thickness and high density lipoprotein cholesterol were similar (p>0.05) among treatments. Results demonstrate that supplementing 18 to 27 mg/kg diet of rice bran octacosanol can improve laying rate and egg quality and reduce blood lipid of laying hens.

The Invulnerability Studies on Data Center Network

Kai Peng,Binbin Huang 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.11

Data center network (DCN) as the core of the cloud platform receives a widespread concern attention. Recently, the main study of these new architectures is limited to load balancing or improvement of architectures while the security study of DCN is still in its preliminary, especially for the vulnerability study. In our previous researches, we mainly concern about the invulnerability study from the protection of important nodes and vita edges. Differ from the previous one, in this paper; we engaged in the invulnerability studies from the perspective of network attack. Taking typical instances of DCN for example, based on invulnerability measurement of the average shortest path distance, we analysis the invulnerability of DCN by choosing deliberate attack and random attack. Experimental results show that for most architectures of DCN, the deliberate attacks of degree get the same result with the deliberate attacks of betweenness, especially, the deliberate attacks of degree are often harmful than betweenness attacks when attack a few nodes. However, from the perspective of random attacks, random attacks of betweenness are more harmful than degree attacks. The main contribution can be summarized as follows. We firstly engaged in the invulnerability research of DCN from the perspective of network attack and then conclude the network invulnerability of DCN by amount of experiments. The result in this paper can be widely used for the protection of DCN.

Are Microfluidics-Based Blood Viscometers Ready for Point-of-Care Applications? A Review

Ong, Peng Kai,Lim, Dohyung,Kim, Sangho Begell House Inc. 2010 Critical reviews in biomedical engineering Vol.38 No.2

<P>In recent years, the engineering of blood viscometers for the diagnosis, prognosis, and prevention of cardiovascular and other diseases has been the subject of significant research interest. Conventional blood viscometers such as rotational viscometers and capillary viscometers typically rely on mechanical techniques in quantifying whole-blood viscosity, a process in which resistance to blood flow is measured in response to an applied force. The direct applicability of conventional viscometers as point-of-care diagnostic and clinical tools is subject to several limitations mainly related to their macro-structural features that augment the sampling size and reduce portability. The development of new fabrication technologies to scale down experimental processes has opened up the reality of miniaturizing existing concepts of blood viscometers into microchips, and paves the road for future development of blood viscometers. These micro-blood viscometers are advantageous because they use very small sample volumes for quick, routine clinical purposes. The easy fabrication of microsystems and large-scale production not only result in a lower cost, but also render these devices portable and disposable, both of which are highly desirable for clinical applications. The underlying challenges of these devices are associated with red blood cell clogging, measurement stability, reliability, and reproducibility. The present review discusses the state-of-the-art and emerging trends in the field of microfluidics to provide elegant solutions for quantifying blood viscosity with vastly improved efficacy and with the potential for use at the patient’s bedside.</P>

Polysufonamide/Stainless Steel Woven Fabrics: Manufacturing Techniques, Flame Retardance and Electromagnetic Shielding Effectiveness

Hao-Kai Peng,YanTing Wang,Ting-Ting Li,Ching-Wen Lou,XiaoXiao Wang,Jia-Horng Lin 한국섬유공학회 2020 Fibers and polymers Vol.21 No.4

In order to make conductive woven fabrics with electromagnetic shielding effectiveness (EMSE) and flameretardance, polysufonamide (PSA)/stainless steel (SS) core yarn are used as the weft yarns and PSA yarns are used as thewarp yarns. The conductive woven fabrics are denoted as SS-60, SS-80, SS-100, SS-120, and SS-140 according to the twistcounts of the core yarn, and evaluated in terms of mechanical properties, flame retardance, surface resistivity. The test resultsshow that the best twist of the core yarn is 120 turns/10 cm. SS-60 has the maximum burnt length, while SS-140 has theminimum burnt length. Moreover, the surface resistivity of the PSA/SS woven fabrics is proportional to the twist counts, andthe surface resistivity along the warp direction is higher than that along the weft direction. Changing the fabric laminationangle can form a complete shielding network, and the EMSE is significantly increased. For SS-80, SS-100, and SS-120,when they are composed of 4-6 layers with lamination angles of 0 o/45 o/90 o/-45 o/0 o/45 o and 0 o/90 o/0 o/90 o/0 o/90 o, theEMSE is above 40 dB and the shielding effect is above 99.99 % against the incident waves at 2000-3000 MHz. Specifically,SS-120 has the maximum EMSE of 64 dB against incident waves at 2844 MHz.

Impedance modeling and stability analysis of modular multilevel converter considering frequency coupling characteristics

Kai Shi,Peng Lu,Yuxin Sun,Peifeng Xu 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.8

In recent years, a series of studies concerning the oscillation of interconnected systems has shown that frequency coupling has important effects on the stability of the system. In this paper, a more accurate theoretical model considering the frequency coupling effects is adopted to derive the transmission process in vector control, phase lock loop, and proportional–resonant controller of the harmonic perturbation in the frequency domain. This model is used to further deepen the application of harmonic linearization modeling to impedance modeling. An integrated three-phase modular multilevel converter simulation model based on the PSCAD platform is built to verify the accuracy of the theoretical modeling through the frequency sweep method. The influence of related system parameters on sequence and coupling impedance is analyzed in detail. The generalized Nyquist criterion is used to study the importance of coupling impedance to the stability analysis of the system.

Installation Time of Ground Support during Tunnel Excavation: A Novel Graph Methodology

Kai Su,Yan-Jun Zhang,Jin-Peng Cui,Cong-An Li 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.12

Installation time of ground support in many caverns excavation is mainly based on analytical and empirical method, instead of the robust numerical simulations. A novel graph method is proposed to determine the installation time of the support upon finite difference method (FDM) simulation. A three dimensional numerical model for the diversion tunnel of Guandi hydropower station is developed. The curve d-r between the convergence d and the excavation unloading rate r is built up upon one-step excavation simulation. Meanwhile, the curve d-l between d and the distance from the tunnel face l, is established via the step-by-step simulation. Using the dimensionless convergence λ instead of d in both curve d-r and curve d-l, curve λ-r and curve λ-l can be yielded to achieve the composite graph r-λ-l. When r = r0, lcan be chose as l0 along the identical λ in the comprehensive graph r-λ-l, where r0 is the excavation unloading rate at the critical plastic state and l0 is the distance from the tunnel face to the support installation location. The proposed graph method is demonstrated to meet well with common sense upon the diversion tunnel of Guandi hydropower station and can be conveniently realized in other engineering practice.

Segmental Liver Stiffness Evaluated with Magnetic Resonance Elastography Is Responsive to Endovascular Intervention in Patients with Budd-Chiari Syndrome

Peng Xu,Lulu Lyu,Haitao Ge,Muhammad Umair Sami,Panpan Liu,Chunfeng Hu,Kai Xu 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.5

Objective: To assess segmental liver stiffness (LS) with MRI before and after endovascular intervention in patients with Budd-Chiari syndrome (BCS). Materials and Methods: Twenty-three patients (13 males and 10 females; mean age, 42.6 ± 12.6 years; age range, 31–56 years) with BCS as a primary liver disease were recruited for this study. Two consecutive magnetic resonance elastography (MRE) examinations were performed before the endovascular treatment. Fifteen patients who underwent endovascular intervention treatment also had follow-up MRE scans within three days after the procedure. LS was measured in three liver segments: the right posterior, right anterior, and left medial segments. Inter-reader and inter-exam repeatability were analyzed with intraclass correlation coefficients (ICCs) and Bland-Altman analysis. Segmental LS and clinical characteristics before and after the intervention were also compared. Results: Within three days of the endovascular intervention, all three segmental LS values decreased: LS of the right posterior segment = 7.23 ± 0.88 kPa (before) vs. 4.94 ± 0.84 kPa (after), LS of the right anterior segment = 7.30 ± 1.06 kPa (before) vs. 4.77 ± 0.85 kPa (after), and LS of the left medial segment = 7.22 ± 0.87 kPa (before) vs. 4.87 ± 0.72 kPa (after) (all p = 0.001). There was a significant correlation between LS changes and venous pressure gradient changes before and after treatments (r = 0.651, p = 0.009). The clinical manifestations of all 15 patients significantly improved after therapy. The MRE repeatability was excellent, with insignificant variations (inter-reader, ICC = 0.839–0.943: inter-examination, ICC = 0.765–0.869). Bland–Altman analysis confirmed excellent agreement (limits of agreement, 13.4–19.4%). Conclusion: Segmental LS measured by MRE is a promising repeatable quantitative biomarker for monitoring the treatment response to minimally invasive endovascular intervention in patients with BCS.

The facile preparation of Cu–Zn–Al oxide composite catalysts with high stability and performance for the production of dimethyl ether using modified aluminum alkoxide

Peng Wanga,Wei Huang,GuangZhi Zhang,Zhi-hua Gao,Yu Tang,Kai Sun,XiaoYu Zhang 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.26 No.-

Modified aluminum alkoxide prepared by alcoholysis was used as an aluminum source in the complete liquid-phase technology for the preparation of slurry catalysts. The use of the modified aluminum alkoxide afforded control over the rate of the hydrolysis/condensation reactions during the preparation of the catalyst precursors, thereby generating catalysts with a fine nano-structured active metal and metallic oxide particles. Four types of Cu–Zn–Al (molar ratio is 2:1:4) catalysts were prepared using different procedures. These catalysts were tested for CO hydrogenation at 553 K, 4.0 MPa and H2/ CO = 1.0 in a kettle with a mechanical agitator. The results indicated that the activity of the catalysts was greatly dependent on the rate of the hydrolysis/condensation reactions, and the catalyst with the best catalytic performance was obtained by controlling the hydrolysis/alcoholysis rate during catalyst synthesis by pre-alcoholysis of AIP as the aluminum source, over which the CO conversion and dimethyl ether selectivity could reach 62.6% and 62.5%, respectively.