Metal-organic frameworks constructed from flexible ditopic ligands: Conformational diversity of an aliphatic ligand

The solvothermal reaction of adipic acid as a flexible ditopic ligand and the metal ions MnII, CoII, and TbIII afforded three novel metal-organic frameworks (MOFs), {[Mn2(adipate) 2(DMA)]} (1), {[Co2(adipate)2(DMF)] ??1DMF??1.5H2O} (2), and {[Tb3(adipate) 4.5(DMF)2]} (3) (DMA = N,N-dimethylacetamide; DMF = N,N-dimethylformamide), respectively, which were structurally characterized by single-crystal X-ray diffraction. Depending on the kind of metal ion and solvent system, the conformations and coordination modes of the adipate ligands were diverse and governed the entire MOF structure. Compound 1 consists of the secondary building units (SBUs) of Mn-O chains that were linked by adipate ligands extending in two-dimensional sheets, which were infinitely stacked in a layer-by-layer manner. Compound 2 presented a three-dimensional MOF constructed from Co-O chains and bridging adipate ligands extending in four different directions. Compound 3 also had a three-dimensional structure which was formed by Tb-O chains connected with adipate ligands in six directions. From these structures, ten different adipate ligands with diverse conformations were found, and the potential energy of each conformation was calculated by the first-principles density function. In addition, the luminescence properties of the Tb-based MOF 3 were investigated in the solid state at room temperature.close0

Effects and Safety of Aqueous Extract of Poncirus fructus

Objective. To investigate the effects and safety of the aqueous extract of the dried, immature fruit of Poncirus trifoliata (L.) Raf., known as Poncirus fructus (PF), in spinal cord injury (SCI) patients with neurogenic bowel. Methods. Thirty-one SCI patients with neurogenic bowel were recruited. Patients were evaluated based on clinical information, constipation score, Bristol Stool Form Scale, stool retention score using plain abdominal radiograph, and colon transit time. PF was administered in dosages of 800 mg each prior to breakfast and lunch for 14 days. Results. The morphological feature of the stool before and after administration indicated a statistically significant difference from 3.52 ± 1.33 to 4.32 ± 1.44 points (p<0.05). Stool retention score before and after administration of PF was represented with low significance (7.25 ± 1.60 to 6.46 ± 1.53 points) in the whole colon (p<0.05), and the colon transit time was significantly shortened (57.41 ± 20.7 to 41.2 ± 25.5 hours) in terms of the whole transit time (p<0.05). Side effects were observed in 7 people (28.0%) consisting of 2 people with soft stools and 5 people with diarrhea. Conclusion. For SCI patients, PF administration significantly improved defecation patterns, defecation retention, and colon transit time. PF could be an effective aid to improve colonic motility and constipation

Torsional Vibration Transduction in a Solid Shaft by MPTs

In this study, we aim to investigate the feasibility to use MPTs (Magnetostrictive Patch Transducers) for torsional vibration measurement in solid ferromagnetic cylinders. MPTs consisting of thin magnetostrictive patches, permanent magnets and a solenoid coil have been widely used for elastic wave transduction in the ultrasound frequency range [1] but they have been seldom used for sonic-frequency range vibration measurement, in spite of their unique wireless transduction characteristics. While a MPT was used in Ref. [2] to perform torsional modal testing in a hollow cylinder or a pipe having relatively small torsional rigidity, no investigation has been reported yet on the use of MPTs in “solid” “ferromagnetic” shafts, common torsional power carrying elements in machines.While we will be mainly focused here on the torsional wave measurement in stationary shafts, the MPT-based torsional measurement can be also applied to rotating shafts. Because the torsional rigidities of solid shafts are much larger than those of hollow cylinders of the same radii, it is important to find optimal MPT configurations, such as the optimal number of rectangular patches to be installed around the surface of a solid shaft. Thereby, we performed numerical investigations and accordingly designed a series of experiments for torsional vibration testing in steel shafts. The actual modal testing experiments with the designed MPTs were found to predict the torsional Eigen-frequencies and Eigen-modes that agree well with the theoretical predictions. Also the relation between the measured vibration signals from MPTs and those from strain gages was checked experimentally and in fact, the experimental result favorably agreed with the theoretical prediction. Potential applications of the MPT-based torsional vibration measurement technique in rotating solid shafts for structural health monitoring are also briefly discussed

Enzymatic analysis of the effect of naturally occurring Leu138Pro mutation identified in SHV β-lactamase on hydrolysis of penicillin and ampicillin

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to analyze the significance of leucine to proline substitution at position 138(Leu138Pro) on the hydrolysis of penicillin and ampicillin that we identified in the <it>bla</it>_SHVgene of clinical <it>Escherichia coli </it>swine isolate.</p> <p>Results</p> <p>Kinetic analysis of the mutant proteins showed that <it>K</it>_{<it>m </it>}value of the purified L138P mutant was comparatively higher than SHV-1, SHV-33 and SHV-33(L138P) enzyme for penicillin and ampicillin. Docking simulation of the SHV-1 and SHV-(L138P) enzymes also confirmed that β-lactamases preferred penicillin to ampicillin and the SHV-1 had a higher binding affinity for antibiotics compared to the SHV-(L138P) and other mutants.</p> <p>Conclusions</p> <p>Our result demonstrated that L138P has a reduced role in penicillin and ampicillin hydrolyzing properties of SHV β-lactamases. These naturally occurring mutations rendering reduced function of the existing protein could trigger the emergence or acquisition of more effective alternative mechanisms for β-lactam hydrolysis.</p