Investigation of the Microstructures of Graphene Quantum Dots (GQDs) by Surface-Enhanced Raman Spectroscopy

Photoluminescence (PL) is the most significant feature of graphene quantum dots (GQDs). However, the PL mechanism in GQDs has been debated due to the fact that the microstructures, such as edge and in-plane defects that are critical for PL emission, have not been convincingly identified due to the lack of effective detection methods. Conventional measures such as high-resolution transmission electron microscopy and infrared spectroscopy only show some localized lattice fringes of GQDs and the structures of some substituents, which have little significance in terms of thoroughly understanding the PL effect. Here, surface-enhanced Raman spectroscopy (SERS) was introduced as a highly sensitive surface technique to study the microstructures of GQDs. Pure GQDs were prepared by laser ablating and cutting highly oriented pyrolytic graphite (HOPG) parallel to the graphite layers. Consequently, abundant SERS signals of the GQDs were obtained on an Ag electrode in an electrochemical environment for the first time. The results convincingly and experimentally characterized the typical and detailed features of GQDs, such as the crystallinity of sp2 hexagons, the quantum confinement effect, various defects on the edges, sp3-like defects and disorders on the basal planes, and passivated structures on the periphery and surface of the GQDs. This work demonstrates that SERS is thus by far the most effective technique for probing the microstructures of GQDs

Multi-Fault Diagnosis of Gearbox Based on Improved Multipoint Optimal Minimum Entropy Deconvolution

Under complicated conditions, the extraction of a multi-fault in gearboxes is difficult to achieve. Due to improper selection of methods, leakage diagnosis or misdiagnosis will usually occur. Ensemble Empirical Mode Decomposition (EEMD) often causes energy leakage due to improper selection of white noise during signal decomposition. Considering that only a single fault cycle can be extracted when MOMED (Multipoint Optimal Minimum Entropy Deconvolution) is used, it is necessary to perform the sub-band processing of the compound fault signal. This paper presents an adaptive gearbox multi-fault-feature extraction method based on Improved MOMED (IMOMED). Firstly, EEMD decomposes the signal adaptively and selects the intrinsic mode functions with strong correlation with the original signal to perform FFT (Fast Fourier transform); considering the mode-mixing phenomenon of EEMD, reconstruct the intrinsic mode functions with the same timescale, and obtain several intrinsic mode functions of the same scale to improve the entropy of fault features. There is a lot of white noise in the original signal, and EEMD can improve the signal-to-noise ratio of the original signal. Finally, through the setting of different noise-reduction intervals to extract fault features through MOMED. The proposed method is compared with EEMD and VMD (Variational Mode Decomposition) to verify its feasibility

Study on Vetiver’s Purification for Wastewater from Pig Farm

Abstract: Nitrogen, phosphorus and heavy metals from pig farms are key sources of water pollution. Wastewater contains nitrogen and phosphorus which are the most important plant nutrients, but is harmful when applied to agricultural land in excess amounts, thereby leading to pollution of ground water by nitrates, surface water by phosphorous (causing eutrophication) and soil by heavy metals such as copper which are used as growth promoters in the feed stuff. The main objective of this paper was to investigate the effects of vetiver (Vetiver zizanioides) in purifying wastewater from pig farms and design a purifying system for pig farms with a Vetiver bamboo float. The results showed that Vetiver had a very high capacity to purify wastewater. It’s ratio of uptake and purification to Cu and Zn> 90%, to As and N> 60%, to P was between 59–85%, to Pb was between 30–71%, and to Hg was between 13–58%. The purifying effects of Vetiver to heavy metals, N, and P from pig farms were ranked as Zn> Cu> As> N> P> Pb> Hg. It is powerful to remove the elements of Cu, Zn, As and N for pig farms

VSC-HVDC transmission line fault location based on transient characteristics

Accurate and reliable fault location is necessary for ensuring the safe and reliable operation of the VSC-HVDC transmission system. This paper proposed a single-terminal fault location method based on the fault transient characteristics of the two-terminal VSCH-VDC transmission system. The pole-to-pole transient fault process was divided into three stages, the time-domain expression of the DC current during the diode freewheel stage was used to locate the fault point, and a criterion for judging whether the fault evolves to the diode freewheel stage was proposed. Taking into account the enhancing effect of the opposite system to the fault current, the DC side pole-to-ground fault networkwas equated to a fourth-order circuit model, the relationship of fault distance with the characteristic roots of fault current differential equationwas derived, and the Prony algorithmwas utilized for datafitting to extract characteristic roots to realize fault location. A two-terminal VSC-HVDC transmission system was modelled in PSCAD/EMTDC. The simulation result verifies that the proposed principle can accurately locate the fault point on the VSC-HVDC transmission lines

The complete mitochondrial genome of Cervus elaphus kansuensis (Artiodactyla: Cervidae) and its phylogenetic analysis

Gansu wapiti (Cervus elaphus kansuensis) is one of eight subspecies of wapiti in China, which has been placed under the second-ranked protected animals by Chinese government. No complete mitochondrial genomes of Gansu wapiti was determined until now, so the phylogenetic relationships among the subspecies of wapiti and other species of the genus Cervus have not been well studied. In this study, the complete mitochondrial genome of C. e. kansuensis was first sequenced and characterized. The genome is 16,430 bp in length, containing 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and one noncoding control region (CR). Maximum-Likelihood (ML) and Bayesian Inference (BI) trees based on the 13 PCGs show that C. e. kansuensis is clustered with other wapiti subspecies in China except for C. e. yarkandensis. It is also shown that Cervus elaphus is not a monophyletic group. This study provides important molecular evidence for the phylogenetic relationship among species in the genus Cervus

Epidermal Growth Factor Promotes Proliferation and Migration of Follicular Outer Root Sheath Cells via Wnt/β-Catenin Signaling

Background/Aims: To investigate the effect and molecular mechanism of EGF on the growth and migration of hair follicle outer root sheath (ORS) cells. Methods: Intact anagen hair follicles were isolated from mink skin and cultured with EGF in vitro to measure ORS daily growth. Meanwhile, purified primary ORS cells were treated or transfected with EGF, and their proliferation and migration were assessed by MTT assay and transwell assay, respectively. The signaling pathway downstream of EGF was characterized by using the Wnt/β-catenin signaling inhibitor, XAV-939. Results: EGF of 2-20 ng/ml, not higher or lower, promoted the growth of follicular ORS in vitro. EGF treatment or overexpression promoted the proliferation and migration of ORS cells. Moreover, EGF stimulation induced nuclear translocation of β-catenin, and upregulated the expression of Wnt10b, β-catenin, EGF receptor and SOX9. Inhibition of Wnt/β-catenin signaling by XAV-939 significantly reduced the basal and EGF-enhanced proliferation and migration of ORS cells. In addition, a number of follicle-regulatory genes, such as Survivin, Msx2 and SGK3, were upregulated by EGF in the ORS cells, which was also inhibited by XAV-939. Conclusion: EGF promotes the proliferation and migration of ORS cells and modulates the expression of several follicle-regulatory genes via Wnt/β-catenin signaling

Administration of Curcumin Protects Kidney Tubules Against Renal Ischemia-Reperfusion Injury (RIRI) by Modulating Nitric Oxide (NO) Signaling Pathway

Background/Aims: To explore the protective effect of curcumin on renal ischemia-reperfusion injury (RIRI) in rats, and its influence on nephridial tissue’s NO and cGMP levels as well as downstream signaling pathway, to elucidate the possible mechanism of curcumin on RIRI. Methods: 36 Sprague Dawley rats (SD rats) were randomly divided into Sham group, Model group, curcumin (CUR +) Model group, 12 rats per group. They were all given RIRI model preparation by unilateral artery occlusion method. All groups’ β2-MG in urine in 24h, serum Cr and BUN were compared, and UAER were calculated. Nitric oxide synthase (NOS), cGMP-dependent protein kinase (PKG), Caspase-3 expression were all determined by western blot. Nitric oxide (NO), NOS and cGMP levels were also examined by using ELISA. All groups’ nephridial histomorphology and kidney tubules score were evaluated and compared. Results: β2-MG and UAER in urine, serum Cr and BUN, in renal tissue were all elevated in Model of RIRI, indicating the success of animal model of RIRI establishment, and above index in CUR + Model group were all lower than those in Model group. Furthermore, iNOS, NO, cGMP, PKG and Caspase-3 in renal tissue were all increased in Model of RIRI, indicating the NO signaling pathway was activated, which is one of the pathogenesis of RIRI, and above index in CUR + Model group were all lower than those in Model group, suggesting that inactivation of iNOS/NO/cGMP/PKG signaling pathway is one of the reasons that explain the protective effect of curcumin in RIRI. Conclusion: The activation of iNOS/NO/cGMP/PKG signaling pathway and the consequent promoted apoptosis of renal tubules are significantly involved in the pathogenesis of development of RIRI, and curcumin treatment could protect renal tubules against RIRI, at least partially, by suppressing the activated iNOS/NO/cGMP/PKG signaling pathway

Effects of dry dietary protein on digestibility, nitrogen-balance and growth performance of young male mink

The experiment was to study the nutrient digestibility and metabolism performance of male minks, which were fed different protein level diets during growth period. Effects of protein quantity on growth and development of minks and feed conversion ratio (FCR) were also investigated. Sixty healthy male minks of 45 d were randomly allocated into six groups with ten replicates, which was one sable for each replicate. The minks in six groups were fed diets in which protein levels were 28, 30, 32, 34, 36 and 38%, respectively. The six groups were denoted as P28, P30, P32, P34, P36 and P38. After 2 wk, all minks were weighed, average daily gains (ADG) were calculated, and the digestibility values of nutrients were determined. The results indicated that digestibility of calcium, nitrogen of fence, nitrogen deposition, net protein utilization (NPU), and biological value of protein (BV) were similar (P > 0.05), however, nitrogen intake greatly varied among groups (P < 0.01). Compared with group P28, groups of P34, P36 and P38 showed significant difference (P < 0.01) in ADG and FCR. In conclusion, it was recommended that adding 34% protein to mink diet would optimize production parameters including ADG, digestibility of nutrition, and FCR, and negative result was observed when diet protein was lower than 28%