Crystal Structure and Catalytic Activity of A Novel Cd(II) Coordination Polymer Formed by Dicarboxylic Ligand

A new Cd(II) coordination polymer, {[Cd3(L)2(DMF)2(H2O)2]·H2O}n (H2L = 1,3-bisbenzyl-2-imidazolidine-4,5-dicarboxylic acid) was synthesized by one-pot synthesis method from 1,3-bisbenzyl-2-imidazolidine-4,5-dicarboxylic acid, NaOH, DMF, and Cd(NO3)2·4H2O. Its structure was determined by elemental analysis and single crystal X-ray diffraction. Structural analysis shows that three Cd(II) ions are all six-coordinated with four oxygen atoms of four 1,3-bisbenzyl-2-imidazolidine-4,5-dicarboxylate ligands and two O atoms from two DMF molecules (Cd1) or two oxygen atoms of two coordinated H2O molecules (Cd2 and Cd3) to form an octahedral coordination geometry. The Cd(II) coordination polymer displays a 1D chained structure by the bridging carboxylate groups from 1,3-bisbenzyl-2-imidazolidine-4,5-dicarboxylate ligands. The conversion of benzaldehyde is 90.9%, which is 40~50% higher than those of the other three aldehydes (4-methylbenzaldehyde, p-methoxybenzaldehyde and 3-chlorobenzaldehyde), so the Cd(II) coordination polymer catalyst shows better catalytic activity for the coupling reaction of benzaldehyde, phenylacetylene, and piperidine than the other three aldehydes. Copyright © 2018 BCREC Group. All rights reserved Received: 25th April 2017; Revised: 11st September 2017; Accepted: 1st November 2017; Available online: 11st June 2018; Published regularly: 1st August 2018 How to Cite: Ji, Z.X., Li, P.F. (2018). Crystal Structure and Catalytic Activity of A Novel Cd(II) Coordination Polymer Formed by Dicarboxylic Ligand. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (2): 220-226 (doi:10.9767/bcrec.13.2.1178.220-226

Experimental study of a new type of floating breakwater

A new type of floating breakwater (FB) is proposed in this paper. Its hydrodynamic performance has been tested. The structure of the new breakwater named cylindrical floating breakwater (CFB) consists of two parts: a main body of rigid cylinders, and a flexible mesh cage containing a number of suspending balls that are intended to absorb the wave energy into their mechanical energy. A series of experiments were carried out on the new floating breakwater and traditional double pontoons and box floating breakwaters to compare their performances. A two-dimensional wave flume was used in the experiment; the incident and transmitted waves, the tensions on the mooring lines and the motion responses of the floating breakwaters were measured. Results showed that the new floating breakwater had a better performance than the traditional double pontoons and the box floating breakwaters: wave transmission was significantly reduced by the mesh cage with the balls, especially for long waves

Linking nutrient strategies with plant size along a grazing gradient: Evidence from Leymus chinensis in a natural pasture

AbstractStudying the changes in nutrient use strategies induced by grazing can provide insight into the process of grassland degradation and is important for improving grassland quality and enhancing ecosystem function. Dominant species in meadow steppe can optimize their use of limiting resources; however, the regulation of nutrient use strategies across grazing gradients is not fully understood. Therefore, in this study, we report an in situ study in which the impact of grazing rates on nutrient use strategies of Leymus chinensis, the dominant plant species in eastern Eurasian temperate steppes, was investigated. We conducted a large randomized controlled experiment (conducted continuously for five years in grassland plots in a natural pasture in Hailar, eastern Mongolia Plateau, China) to assess the effects of grazing rate treatments (0.00, 0.23, 0.34, 0.46, 0.69, and 0.92 adult cattle unit (AU) ha−1) on L. chinensis along a grazing gradient and employed a random sampling approach to compare the accumulation, allocation, and stoichiometry of C, N, and P in leaves and stems. Our findings demonstrated the follows: (i) The height of L. chinensis decreased with an increase in the grazing gradient, and the concentrations of C, N, and P significantly increased; (ii) the accumulation of C, N, and P per individual was negatively correlated with the concentration of aboveground tissues, suggesting that there was a tradeoff in L. chinensis between nutrient accumulation and concentration at the individual scale; (iii) the leaf-to-stem ratio of C, N, and P accumulation increased with grazing intensity, indicating a tradeoff in nutrient allocation and plant size at the individual plant level; and (iv) grazing rates were negatively correlated with the ratios of C:N and C:P in the stem; however, these ratios in leaves significantly increased with grazing intensity. Our findings suggest that L. chinensis in meadow steppe adapts to grazing disturbance through tradeoffs between plant size and nutrient use strategies. Moreover, our results imply that grazing produces a compensatory effect on nutrient use efficiency between the stems and leaves of L. chinensis

Visualizing the elongated vortices in γ\gamma-Ga nanostrips

We study the magnetic response of superconducting $\gamma$-Ga via low temperature scanning tunneling microscopy and spectroscopy. The magnetic vortex cores rely substantially on the Ga geometry, and exhibit an unexpectedly-large axial elongation with aspect ratio up to 40 in rectangular Ga nano-strips (width $l$ $<$ 100 nm). This is in stark contrast with the isotropic circular vortex core in a larger round-shaped Ga island. We suggest that the unusual elongated vortices in Ga nanostrips originate from geometric confinement effect probably via the strong repulsive interaction between the vortices and Meissner screening currents at the sample edge. Our finding provides novel conceptual insights into the geometrical confinement effect on magnetic vortices and forms the basis for the technological applications of superconductors.Comment: published in Phys. Rev. B as a Rapid Communicatio

Recent Developments and Applications of Hemicellulose From Wheat Straw: A Review

Hemicellulose is an important component of plant cell walls, which is mainly used in biofuels and bioproducts. The hemicellulose extracted from different plant sources and plant locations has different microstructure and molecule. Wheat straw is an important biomass raw material for the extraction of hemicellulose. The aims of this review are to summary the recent developments and various applications of hemicellulose from wheat straw. The microstructure and molecule of hemicellulose extracted by different methods are comparably discussed. The hemicellulose-based derivatives and composites are also reviewed. Special attention was paid to the applications of hemicellulose such as biofuel production, packaging field, and adsorbent. The problems and developing direction were given based on our knowledge. We expect that this review will put forward to the development and high-value applications of hemicellulose from wheat straw

CT volumetry can potentially predict the local stage for gastric cancer after chemotherapy

PURPOSE:We aimed to evaluate the value of CT tumor volumetry for predicting T and N stages of gastric cancer after chemotherapy, with pathologic results as the reference standard.METHODS:This study retrospectively evaluated 42 patients diagnosed with gastric cancer, who underwent chemotherapy followed by surgery. Pre- and post-treatment CT tumor volumes (VT) were measured in portal venous phase and volume reduction ratios were calculated. Correlations between pre- and post-treatment VT, reduction ratio, and pathologic stages were analyzed. Receiver operator characteristic (ROC) analyses were also performed to assess diagnostic performance for prediction of downstaging to T0–2 stage and N0 stage.RESULTS:Pretreatment VT, post-treatment VT, and VT reduction ratio were significantly correlated with T stage (rs=0.329, rs=0.546, rs= -0.422, respectively). Post-treatment VT and VT reduction ratio were significantly correlated with N stage (rs=0.442 and rs= -0.376, respectively). Pretreatment VT, post-treatment VT, and VT reduction ratio were significantly different between T0–2 and T3,4 stage tumors (P = 0.05, P < 0.001, and P = 0.002, respectively). The differences between N0 and ≥N1 groups were also statistically significant (P = 0.005 for post-treatment VT, P = 0.016 for VT reduction ratio, respectively). The area under the ROC curve (AUC) for identification of T0–2 groups was 0.70 for pretreatment VT, 0.88 for post-treatment VT, and 0.82 for VT reduction ratio, respectively. AUC was 0.78 for post-treatment VT and 0.74 for VT reduction ratio for identification of N0 groups.CONCLUSION:CT tumor volumetry, particularly post-treatment measurement of VT, is potentially valuable for predicting histopathologic T and N stages after chemotherapy in patients with gastric cancer

The median effective concentration of epidural ropivacaine with different doses of dexmedetomidine for motor blockade: an up-down sequential allocation study

Study objectiveRecent studies have shown that dexmedetomidine can be safely used in peripheral nerve blocks and spinal anesthesia. Epidural administration of dexmedetomidine produces analgesia and sedation, prolongs motor and sensory block time, extends postoperative analgesia, and reduces the need for rescue analgesia. This investigation seeks to identify the median effective concentration (EC50) of ropivacaine for epidural motor blockade, and assess how incorporating varying doses of dexmedetomidine impacts this EC50 value.DesignProspective, double-blind, up-down sequential allocation study.SettingOperating room, post-anesthesia care unit, and general ward.InterventionsOne hundred and fifty patients were allocated into five groups in a randomized, double-blinded manner as follows: NR (normal saline combined with ropivacaine) group, RD0.25 (0.25 μg/kg dexmedetomidine combined with ropivacaine) group, RD0.5 (0.5 μg/kg dexmedetomidine combined with ropivacaine) group, RD0.75 (0.75 μg/kg dexmedetomidine combined with ropivacaine) group, RD1.0 (1.0 μg/kg dexmedetomidine combined with ropivacaine) group. The concentration of epidural ropivacaine for the first patient in each group was 0.5%. Following administration, the patients were immediately placed in a supine position for observation, and the lower limb motor block was assessed every 5 min using the modified Bromage score within 30 min after drug administration. According to the sequential method, the concentration of ropivacaine in the next patient was adjusted according to the reaction of the previous patient: effective motor block was defined as the modified Bromage score &gt; 0 within 30 min after epidural administration. If the modified Bromage score of the previous patient was &gt;0 within 30 min after drug administration, the concentration of ropivacaine in the next patient was decreased by 1 gradient. Conversely, if the score did not exceed 0, the concentration of ropivacaine in the next patient was increased by 1 gradient. The up-down sequential allocation method and probit regression were used to calculate the EC50 of epidural ropivacaine.MeasurementsAdverse events, hemodynamic changes, demographic data and clinical characteristics.Main resultsThe EC50 of epidural ropivacaine required to achieve motor block was 0.677% (95% CI, 0.622–0.743%) in the NR group, 0.624% (95% CI, 0.550–0.728%) in the RD0.25 group, 0.549% (95% CI, 0.456–0.660%) in the RD0.5 group, 0.463% (95% CI, 0.408–0.527%) in the RD0.75 group, and 0.435% (95% CI, 0.390–0.447%) in the RD1.0 group. The EC50 of the NR group and the RD0.25 group were significantly higher than that of the RD0.75 and the RD1.0 groups, and the EC50 of the RD0.5 group was significantly higher than that of the RD1.0 group.ConclusionThe EC50 of epidural ropivacaine required to achieve motor block was 0.677% in the NR group, 0.624% in the RD0.25 group, 0.549% in the RD0.5 group, 0.463% in the RD0.75 group, and 0.435% in the RD1.0 group. Dexmedetomidine as an adjuvant for ropivacaine dose-dependently reduce the EC50 of epidural ropivacaine for motor block and shorten the onset time of epidural ropivacaine block. The optimal dose of dexmedetomidine combined with ropivacaine for epidural anesthesia was 0.5 μg/kg