Column Size Research Articles

Isolation and assessment of acidic and neutral oligosaccharides from goat milk and bovine colostrum for use as ingredients of infant formulae

Acidic and neutral oligosaccharides (OSs) from goat milk or bovine colostrum were assessed for the potential uses as ingredients of infant formulae or functional foods. For that purpose, neutral and acidic OS fractions were isolated by a modified charcoal column method. The elution protocol of the charcoal column was improved to decrease the column size to approximately 1/9 of the traditional process. Then the inhibitory potencies of the neutral and acidic OSs isolated from the two mammals were compared at 2.5 and 5.0 mg mL−1 using OSs from human breast milk as a reference. These OS fractions inhibited the adhesion of Salmonella enterica to Caco-2 cells, although some differences were not statistically significant. Finally, goat milk OSs were determined as more potential ingredients of infant formulae or functional foods in the aspect of the potency of adherence inhibition, safety, and the availability of the starting material.

Designing safer composite helmets to reduce rotational accelerations during oblique impacts.

Oblique impact is the most common accident situation that occupants in traffic accidents or athletes in professional sports experience. During oblique impact, the human head is subjected to a combination of linear and rotational accelerations. Rotational movement is known to be responsible for traumatic brain injuries. In this article, composite foam with a column/matrix composite configuration is proposed for head protection applications to replace single-layer uniform foam, to better attenuate rotational movement of the head during oblique impacts. The ability of composite foam in the mitigation of rotational head movement is studied by performing finite element (FE) simulations of oblique impact on flat and helmet shape specimens. The performance of composite foam with respect to parameters such as compliance of the matrix foam and the number, size and cross-sectional shape of the foam columns is explored in detail, and subsequently an optimized structure is proposed. The simulation results show that using composite foam instead of single-layer foam, the rotational acceleration and velocity of the headform can be significantly reduced. The parametric study indicates that using a more compliant matrix foam and by increasing the number of columns in the composite foam configuration, the rotation can be further mitigated. This was confirmed by experimental results. The simulation results were also analyzed based on global head injury criteria such as head injury criterion, rotational injury criterion, brain injury criterion and generalized acceleration model for brain injury threshold which further confirmed the superior performance of composite foam versus single-layer homogeneous expanded polystyrene foam. The findings of simulations give invaluable information for design of protective helmets or, for instance, headliners for the automotive industry.

Stability indicating HPLC method for the simultaneous determination of dapagliflozin and saxagliptin in bulk and tablet dosage form

Abstract A simple, fast, and highly selective RP-HPLC method was developed for the determination of Dapagliflozin (DAP) and Saxagliptin (SAX) in API and tablet dosage form. The separation was done using a Xterra RP18 (4.6×150 mm, 5 μm particle size) column with Acetonitrile: water (60:40). The isocratic elution mode at a flow rate of 1 mL/min, and the analytes were measured at 248 nm. The retention time for DAP and SAX were about 2.091 and 3.249 min, respectively. Calibration curves were found to be linear in the ranges of 100-500 μg/ml for DAP and 50-250 μg/ml for SAX, with correlation coefficients of 0.9998. The detection and quantification values for DAP was 3.0 and 9.98 μg/ml and SAX was 3.02 and 10 μg/ml respectively.

METHOD DEVELOPMENT, VALIDATION AND STABILITY STUDIES FOR DETERMINATION OF BUMETANIDE IN BULK AND PHARMACEUTICAL DOSAGE FORM BY RP-UPLC

Objective: The objective of the study was to develop a new, simple, accurate, precise and reproducible RP-UPLC method for the estimation of bumetanide in bulk and pharmaceutical dosage form.Methods: Acquity SB C18, 2 x 100 mm, 1.8 µmm, 5m particle size column with the mobile phase consisting of water: acetonitrile in the ratio of 30:70 v/v were used. The effluents were moniRTat 254 nm and the flow rate was 1.0 ml/minute.Results: The retention time was 0.852 min. Quantitative linearity was obeyed in the concentration range of 12.5 to 75 μg/ml. The correlation coefficient for bumetanide was found to be 0.999. Recovery and assay studies of bumetanide were within 99 to 102%, indicating that the proposed method can be adaptable for quality control analysis of bumetanide. The % RSD for precision and accuracy of the method was found to be less than 2%. Bumetanide was subjected to stress environment of degradation in aqueous solutions including oxidation, hydrolysis, thermal and photolysis degradation.Conclusion: Proposed method was found to be simple, accurate, precise, and quick and can be used for regular analysis. This condition was applied to tablet dosage form. The statistical parameters and recovery studies were reported.

A comparison of Selective Laser Melting with bulk rapid solidification of AlSi10Mg alloy

In Selective Laser Melting (SLM) layers of atomized powder are spread sequentially on a building platform and melted locally by a laser beam. The melt pool is quenched by the underlying material. SLM of AlSi10Mg alloys results in the development of microstructures consisting of supersaturated primary Al-rich phase surrounded by varied amounts of Al-Si eutectic. The origin of such microstructure is not fully understood. For insight into this issue, this work compares the results of processing AlS10Mgi alloys by SLM and by single-step rapid solidification techniques: Melt Spinning (MS) and Copper Mould Casting (CMC) achieving a range of cooling rates and microstructures which are analysed by means of microscopy, XRD and DSC.The results obtained in these experiments together with the literature available on rapidly solidified Al-Si alloys suggest a correlation among microstructures of the products made with the three techniques. Data on lattice parameter and enthalpy of Si precipitation from primary Al concur in indicating that Si supersaturation scales in the order SLM > CMC > MS. The type and size of microstructural features, i.e. cells, columns, fibrous and lamellar eutectic, reveal the role of solidification conditions (undercooling, recalescence) and precipitation in the solid state for all techniques. Dendrite growth modelling validates the solidification results.

Failure mechanism of fiber-reinforced polymer-confined concrete column with initial defects

The effect of initial defect size on the mechanical behavior and failure mode of carbon fiber-reinforced polymer- confined concrete column was investigated through theoretical analysis, finite element software simulation and experiment validation. Qualitative theoretical analysis was firstly explored to study the effect of initial defect size on the mechanical behavior of confined concrete column from macro to micro perspective. Numerical simulations and experimental investigation were then carried out and compared to investigate the mechanical behavior of carbon fiber-reinforced polymer-confined concrete column with initial defects under axial compression and eccentric compression. The variation of defect criticality was investigated by varying the layer number of carbon fiber-reinforced polymer and cross-section size of concrete columns. The effect of initial defect size on the failure mode of carbon fiber-reinforced polymer-confined concrete column was finally demonstrated.

Effect of Column Base Flexibility on Earthquake-Induced Residual Deformations of Steel Columns

Post-earthquake residual deformations often control decisions regarding potential demolition of earthquake-damaged buildings. While residual deformations are typically assumed to be lateral, the column residual axial shortening has similar implications for such decisions. This paper investigates the effect of column base flexibility on residual axial shortening of columns in steel moment resisting frames (MRFs). The mechanistic reason for this dependency is that higher base flexibility reduces plastic rotation demands in the column, in turn mitigating local buckling-induced shortening. To investigate this issue, parametric finite element (FE) simulations interrogate various column sizes used in conventional mid-to high-rise steel MRFs. The simulations suggest at 1-2% story drifts, the base flexibility virtually eliminates the column axial shortening.

Unexpected Diffusion Anisotropy of Carbon Dioxide in the Metal-Organic Framework Zn2(dobpdc).

Metal-organic frameworks are promising materials for energy-efficient gas separations, but little is known about the diffusion of adsorbates in materials featuring one-dimensional porosity at the nanoscale. An understanding of the interplay between framework structure and gas diffusion is crucial for the practical application of these materials as adsorbents or in mixed-matrix membranes, since the rate of gas diffusion within the adsorbent pores impacts the required size (and therefore cost) of the adsorbent column or membrane. Here, we investigate the diffusion of CO2 within the pores of Zn2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) using pulsed field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations. The residual chemical shift anisotropy for pore-confined CO2 allows PFG NMR measurements of self-diffusion in different crystallographic directions, and our analysis of the entire NMR line shape as a function of the applied field gradient provides a precise determination of the self-diffusion coefficients. In addition to observing CO2 diffusion through the channels parallel to the crystallographic c axis (self-diffusion coefficient D∥ = (5.8 ± 0.1) × 10-9 m2 s-1 at a pressure of 625 mbar CO2), we unexpectedly find that CO2 is also able to diffuse between the hexagonal channels in the crystallographic ab plane (D⊥ = (1.9 ± 0.2) × 10-10 m2 s-1), despite the walls of these channels appearing impermeable by single-crystal X-ray crystallography and flexible lattice MD simulations. Observation of such unexpected diffusion in the ab plane suggests the presence of defects that enable effective multidimensional CO2 transport in a metal-organic framework with nominally one-dimensional porosity.

Evaluation of the ability of calcite, bentonite and barite to enhance oil dispersion under arctic conditions

A test program was conducted at laboratory and pilot scale to assess the ability of clays used in drilling mud (calcite, bentonite and barite) to create oil-mineral aggregates and disperse crude oil under arctic conditions. Laboratory tests were performed in order to determine the most efficient conditions (type of clay, MOR (Mineral/Oil Ratio), mixing energy) for OMA (Oil Mineral Aggregate) formation. The dispersion rates of four crude oils were assessed at two salinities. Dispersion was characterized in terms of oil concentration in the water column and median OMA size. Calcite appeared to be the best candidate at a MOR of 2:5. High mixing energy was required to initiate OMA formation and low energy was then necessary to prevent the OMAs from resurfacing. Oil dispersion using Corexit 9500 was compared with oil dispersion using mineral fines.

Axial Behaviour of Glass Fibre Reinforced Polymer-Confined Reinforced Concrete Short Columns

Fibre-reinforced polymer (FRP) jacketing is an effective confinement tool for reinforced concrete (RC) columns. To avoid the excessive stress concentration in square-shaped columns, a jacketing technique with rounded column edges needs to be practiced. The load-carrying capacity of RC square short columns wrapped with glass FRP (GFRP) on axial loading was investigated. The effi­ciency of confinement offered by improved jacketing schemes with different corner radii of the column, number of layers of FRP and various vertical distri­bution methods of jacketing are compared. The experimental study was con­ducted on 31 columns of size 140 mm x 140 mm x 1200 mm with one, two and three layers of FRP distributed over one-fourth, one-third and full length of the column. The corner radii of the columns were 0,12.5, 25 and 37.5 mm. Spe­cimens were loaded to the failure modes in concentric uniaxial compression, and the behaviour of the specimens was analysed. An analytical model for the ultimate load-carrying capacity of RC square columns confined by GFRP is proposed from the test results.

Geotextile Encapsulation as Protection to Lime Column under Shear Load

Deep lime stabilization such as lime column, can effectively improve the problematic soft clay through stabilization, settlement reduction and embankment stabilization. Nevertheless, the reduction of lime column load capacity was often encountered due to the column lateral displacement which was induced by high lateral earth pressure in embankments and deep excavation. In order to protect and enhance the mobilization of lime column strength, geotextile encapsulation was proposed for lime column. In this study, large shear box tests were conducted on lime column and geotextile encapsulated lime column (GELC) stabilized Pontian marine clay samples with different column sizes and curing ages, in order to investigate the performance of geotextile encapsulation on lime column in Pontian marine clay under shear loading. It was found that geotextile encapsulation effectively increased the horizontal shear resistance of lime column and protected the column from defect due to lateral displacement, especially at early age when modification was still in process. Geotextile encapsulation also successfully protected lime column from shear and bending failure under lateral load.

A New stability indicating liquid chromatographic method for the quantification of Fingolimod-An Immunomodulating drug

The authors have proposed a new stability indicating RP-HPLC method for the determination of Fingolimod capsules. Symmetry C18 (150 x 4.6 mm, 5µm particle size) column was used for the chromatographic separation with 0.1 % Trifluoro acetic acid: Acetonitrile (50: 50, v/v) mixture as mobile phase. Fingolimod was monitored at 220 nm (UV detector) and the elution was on gradient mode.The flow rate was 1.2 mL/min and the total run time is 10mins. Forced degradation studies were performed to verify the specificity of the method. Beer-Lambert’s law was obeyed over the concentration range 0.5-75 µg/mL with linear regression equation, y = 58537x + 10039 and correlation coefficient 0.9999. The LOD and LOQ are found to be 0.0129 and 0.4061 µg/mL respectively. The proposed method was validated as per ICH guidelines.

Development and Validation of a Stability-indicating Method for the Simultaneous Estimation of Sofosbuvir and Ledipasvir by RP-HPLC

A stability indicating reversed-phase high-performance liquid chromatography method was developed and validated for simultaneous quantification of sofosbuvir and ledipasvir in tablets. The chromatographic separation was done in an isocratic mode using the Discovery C18 (250×4.6 mm, 5 µ particle size) column. The mobile phase 0.1 % ortho phosphoric acid and acetonitrile 45:55 (% v/v) at a flow rate of 1.0 ml/min and at ambient temperature was used. The wavelength used for detection was 270 nm. The retention time for sofosbuvir was found to 2.08 min and that of ledipasvir was 3.06 min. Sofosbuvir and ledipasvir were linear in the concentration ranges of 100 to 600 µg/ml and 22.5 to 135 µg/ml, respectively. The developed method was validated and found to be accurate, specific and robust. Both the drugs were subjected to the stressed conditions like acidic, basic, oxidative, photolytic and thermal conditions. The degradation results were found satisfactory. This method could be applied for the simultaneous estimation of sofosbuvir and ledipasvir in tablets.

Field Tests and Simulation of Ground and Building Vibrations Caused by Metros on an Elevated Bridge

The vibration induced by metros is having a growing impact on people’s daily work and life. This paper proposes a propagation rule and an evaluation method for vibration based on experimental data on the ground and inside a 4-story building subjected to trains running on an elevated bridge in Guangzhou, China. This paper discusses the propagation characteristics of the vibration wave in different directions on the ground and inside the building. Then, a vibration level attenuation model of an elevated bridge section of Guangzhou was built using a linear regression method. Moreover, a finite-element model of a test building was built to study the influence of the building structure on the building vibration response. The results reveal that vertical vibrations are much larger than the horizontal vibrations on the ground and inside the building near the elevated bridge. This paper found a rebound acceleration area at a distance of 10–15 m away from the bridge. Inside the four-story building, the acceleration levels increased gradually with increasing floor level. Slab thickness had little effect on the vibration and the story height of the building along the elevated bridge should be limited to below 3.7 m. Moreover, proper column size can effectively reduce building vibrations.

Evaluation of Seismic Performance of Floating Column Building

In the modern multi-story construction, floating column is an unavoidable feature of buildings. Such features are highly undesirable in building built in seismic prone areas. This study highlights the performance of floating column building and compared with normal building under seismic load. In this study, static and dynamic analyses using response spectrum method have been carried out for multi-story building with and without floating columns. Different cases of the building have been studied by varying the location of floating column and increasing the column size. The results showed that story displacement increased by 56.96% in floating column building compared to normal building. Torsional irregularity was found when floating column was introduced unsymmetrically. It was also found that fundamental time period was increasing in floating column building and lateral stiffness was decreasing in floating column building. When the lost cross sectional area due to floating columns were distributed among ground floor columns then it was found that story displacement as well as fundamental time period decreased and lateral stiffness increased.

Behaviour of punching shear in normal RC slab and waffle slab

This study presents the behaviour of punching shear in waffle slabs at slab–column joints subjected to concentric loading. Although it was observed that waffle slabs are very similar to that of flat slabs, the shear capacity is relatively reduced because some of the potential surfaces are lost when it extends into waffle section. The current IS code of practice does not consider the punching shear mechanism of waffle slabs. For the different sizes of waffle slab a square column size of 100 × 100 mm is considered for the designed slab size of 1200 × 1200 mm. Waffle slabs of different sizes are created by increasing the depth of slab by 20%, width of the rib by 25% and also increasing the solid section. The experimental results were compared with theoretical values from IS code. The comparison of the test results reveals that waffle slab gives more strength than conventional slab. The comparison has been made for the waffle slab of different sizes; slab provided with more depth and thickness of ribs gives extra strength to the structure against punching shear and the stiffness of the slab is substantially improved in the case of an increase in the rib size.

RP-HPLC Method Development and Validation of Regorafenib in pure Form and Pharmaceutical Dosage Form

A new, simple, accurate, precise, robust and isocratic RP-HPLC method has been developed and subsequently validated for the determination of Regorafenib in pure form and pharmaceutical dosage forms as per ICH guidelines. The separation achieved on a Symmetry C18 Column, 250 mmx4.6 mm i.d. and 5μm particle size column as a stationary phase and Methanol: Phosphate buffer (pH adjusted to 4.80 with phosphoric acid) in the ratio of 70: 30v/v used as mobile phase at a flow rate of 1.0 ml/min. The UV detection was performed at 268nm. The retention time for Regorafenib was found to be 3.544minutes. The detector response was linear in the concentration range of 0–16μg/ml. The respective linear regression equation being Y=58945.x+9634 with R2=0.999. The percentage of Regorafenib in pharmaceutical dosage form was found to be within the limits. The limit of detection and the limit of quantification were found to be 0.90μg/ml and 2.90μg/ml respectively. The results of the study showed that, the proposed RP-HPLC method was simple, rapid, precise, accurate and stability indicating, which can be used for the routine determination of Regorafenib in pure form and pharmaceutical dosage forms.

A STABILITY INDICATING MICELLAR LIQUID CHROMATOGRAPHIC METHOD FOR THE DETERMINATION OF DEFERASIROX IN SOLUBILIZED SYSTEM

A simple, isocratic and stability indicating micellar liquid chromatographic (MLC) method containing a surfactant solution above its critical micellar concentration (CMC) was developed and validated for determination of Deferasirox (BTBA) content in active pharmaceutical ingredient and its pharmaceutical formulations. The analysis was performed in on isocratic mode at 400C temperature through Thermo Hypersil ODS 100mmA—4.6mm, 3 µm particle size columns. The UV detection wavelength was set at 250 nm in the mobile phase containing 0.1 M Cetyl trimethyl ammonium bromide (CTAB) buffer (pH – 2.5) and 10% 1-butanol. The method was successfully validated following as per the requirements of ICH guidelines. The proposed method was successfully applied as stability indicating method for determination of BTBA under different stressed conditions. The method allows accurate and reliable determination of BTBA for drug stability assay in pharmaceutical investigations.

Determination of Fenpyroximate from Four Types of Honey by Liquid Chromatography/Tandem Mass Spectrometry

Fenpyroximate is an acaricide used to control phytophagous mites in beekeeping farms, and is used to regulate residual amounts in honey in European Union countries. An effective and accurate sample preparation method was established for a liquid chromatograph‐mass spectrometer/mass spectrometer (LC–MS/MS) analysis of four types of honey (acacia honey, wild honey, manuka, and chestnut honey). Experiments were carried out to determine the optimal values of parameters such as sample pH, type of solid‐phase cartridge, type and volume of extraction solvent, loading sample volume, type and volume of eluent for effective sample extraction, purification, and concentration. Chromatographic separation was performed using a C18 (3.0 mm i.d. × 50 mm length, 2.7 μm particle size) column under isocratic conditions of water and acetonitrile (30:70). The optimized parameters for the extraction of fenpyroximate are as follows: sample pH, 7; type of sorbent solid phase, aminopropyl; volume of extraction solvent, 20 mL; volume of loading sample, 2 mL; eluent, dichloromethane/n‐hexane (65/35%, v/v); eluent volume, 6 mL. The limits of detection and quantitation for spiked honey samples were 1.56 and 5.00 μg/kg, respectively. Linear correlation coefficient (r) obtained from a concentration range 5.00–50.0 μg/kg was 0.9914–0.9977, while the accuracy and precision were 87.99–119.06% and 0.68–14.71% (RSD), respectively. Residue monitoring of fenpyroximate was also performed on 30 commercially available honeys using established methods.

The cyclic performance of reinforced concrete columns using the lap‐spliced crosstie and lap‐spliced inner hoop

A lap‐spliced crosstie consists of two J‐shaped steel bars (rebars) that have a straight end and an end featuring a 180° hook. A lap‐spliced inner hoop is the lap splice of two U‐bars. In this study, cyclic load test was conducted on four large‐sized reinforced concrete (RC) columns to investigate the cyclic performance of RC columns comprising lap‐spliced crossties and lap‐spliced inner hoops. The research results are presented as follows: (a) The ductility of the specimens that adopted the lap‐spliced crossties and lap‐spliced inner hoops was significantly superior to that of the specimens using conventional crossties and crossties featuring a 180° hook on the two ends. (b) The use of the lap‐spliced crossties and lap‐spliced inner hoops may significantly improve the constructability of crossties over the conventional crossties; however, the amount of transverse reinforcement used is most likely to increase. (c) The lap‐spliced crosstie and lap‐spliced inner hoop were formed on the basis of the tension lap splice of rebars. Therefore, column size has to be large enough to meet the minimum requirement for tension lap splice of rebars when lap‐spliced crosstie or lap‐spliced inner hoop is to be used.