Simulation of coalescence, break up and mass transfer in bubble columns by using the Conditional Quadrature Method of Moments in OpenFOAM

The evaluation of the mass transfer rates and the fluid-dynamics aspects of bubble columns are strongly affected by the intrinsic poly-dispersity of the gas phase, namely the different dispersed bubbles are usually distributed over a certain range of size and chemical composition values. In our previous work, gas-liquid systems were investigated by coupling Computational Fluid Dynamics with mono-variate population balance models (PBM) solved by using the quadrature method of moments (QMOM). Since mass transfer rates depend not only on bubble size, but also on bubble composition, the problem was subsequently extended to the solution of multi-variate PBM (Buffo et al. 2013). In this work, the conditional quadrature method of moments (CQMOM) is implemented in the open-source code OpenFOAM for describing bubble coalescence, breakage and mass transfer of a realistic partially aerated rectangular bubble column, experimentally investigated by Diaz et al.(2008). Eventually, the obtained results are here compared with the experimental data availabl

SIMULATION OF A REACTIVE GAS-LIQUID SYSTEM WITH QUADRATURE-BASED MOMENTS METHOD

The description of the interaction between fluid dynamics and fast chemical reactions in gas-liquid systems is complicated by the fact that the gas phase is poly-dispersed, namely it is constituted by bubbles characterized by a distribution of velocity, size and composition values. Phase coupling can be successfully described only if the modeling approach acknowledges the existence of this distribution, whose evolution in space and time is governed by the so-called Generalized Population Balance Equation (GPBE). A computationally efficient approach for solving the GPBE is represented by the Quadrature-Based Moment Methods (QBMM), where the evolution of the entire bubble population is recovered by tracking some specific moments of the distribution. In the present work, one of these methods, the Conditional Quadrature Method of Moments (CQMOM) has been implemented in the OpenFOAM two-fluid solver compressibleTwoPhaseEulerFoam , to simulate a chemically reacting gas-liquid system. To reduce the computational time and increase stability, a second-order operator-splitting technique for the solution of the chemically reacting species was also implemented, allowing to solve the different processes involved with their own time-scale. This modeling approach is here validated by comparing predictions with experiments, for the chemical absorption of CO 2 in NaOH solution, performed in a rectangular bubble column

Pengaruh Komitmen Organisasi Terhadap Kinerja Pegawai Pada Dinas Pendidikan Kota Gorontalo

Penelitian ini bertujuan untuk mengetahui pengaruh komitmen organisasi terhadap kinerja pegawai di Dinas Pendidikan Kota Gorontalo. Metode penelitian yang digunakan dalam penelitian ini adalah metode kuantitatif dengan pendekatan deskriptif. Data yang digunakan diperoleh dari penyebaran kuesioner kepada 92 orang pegawai Dinas Pendidikan Kota Gorontalo. Data dianalisis dengan program SPSS Versi 20. Hasil penelitian menunjukkan bahwa hasil uji regresi komitmen organisasi berpengaruh positif dan signifikan terhadap kinerja pegawai di Dinas Pendidikan Kota Gorontalo. Berdasarkan perhitungan koefisien determinasi diperoleh nilai R Square 0,632 atau 63,2% nilai ini menunjukkan bahwa sebesar 63,2% variabel kinerja pegawai dapat dijelaskan oleh komitmen organisasi, sedangkan sisanya 36,8% dijelaskan oleh variabel lain yang tidak diteliti dalam penelitian ini seperti kepuasan kerja, disiplin kerja, dan motivasi kerja

Two hadron production in e+e- annihilation to next-to-leading order accuracy

We discuss the production of two hadrons in e+e- annihilation within the framework of perturbative QCD. The cross section for this process is calculated to next-to-leading order accuracy with a selection of variables that allows the consideration of events where the two hadrons are detected in the same jet. In this configuration we contemplate the possibility that the hadrons come from a double fragmentation of a single parton. The double-fragmentation functions required to describe the transition of a parton to two hadrons are also necessary to completely factorize all collinear singularities. We explicitly show that factorization applies to next-to-leading order in the case of two-hadron production.Comment: 13 pages, 4 figure

Dbl oncogene expression in MCF-10 A epithelial cells disrupts mammary acinar architecture, induces EMT and angiogenic factor secretion.

The proteins of the Dbl family are guanine nucleotide exchange factors (GEFs) of Rho GTPases and are known to be involved in cell growth regulation. Alterations of the normal function of these proteins lead to pathological processes such as developmental disorders, neoplastic transformation, and tumor metastasis. We have previously demonstrated that expression of Dbl oncogene in lens epithelial cells modulates genes encoding proteins involved in epithelial-mesenchymal-transition (EMT) and induces angiogenesis in the lens. Our present study was undertaken to investigate the role of Dbl oncogene in epithelial cells transformation, providing new insights into carcinoma progression. To assess how Dbl oncogene can modulate EMT, cell migration, morphogenesis, and expression of pro-apoptotic and angiogenic factors we utilized bi- and three-dimensional cultures of MCF-10░A cells. We show that upon Dbl expression MCF-10░A cells undergo EMT. In addition, we found that Dbl overexpression sustain

Pengaruh Kepemimpinan Partisipatif Terhadap Perilaku Kerja Pegawai Pada Dinas Penanaman Modal ESDM Dan Transmigrasi Provinsi Gorontalo

Penelitian ini bertujuan untuk mengetahui Pengaruh Kepemimpinan Partisipatif Terhadap Perilaku Kerja Pegawai. Metode penelitian yang digunakan dalam penelitian ini adalah metode kuantitatif dengan pendekatan kuantitatif deskriptif. Data yang digunakan adalah data primer yang diperoleh dari penyebaran kuesioner kepada pegawai di Dinas Penanaman Modal ESDM dan Transmigrasi Provinsi Gorontalo. Penarikan sampel dalam penelitian ini menggunakan rumus Slovin sehingga jumlah responden berjumlah 57. Analisis data dalam penelitian ini menggunakan analisis regresi linier sederhana dengan bantuan program SPSS 21. Hasil penelitian menunjukkan kepemimpinan partisipatif berpengaruh positif terhadap perilaku kerja pegawai. Koefisien determinasi dalam penelitian ini sebesar 55,4% yang berarti variabilitas perilaku kerja pegawai dapat dijelaskan oleh kepemimpinan partisipatif sebesar 55,4%. Sementara 44,6% dipengaruhi oleh variabel lain seperti kepemimpinan transformasional, lingkungan kerja, budaya organisasi, dan lain-lain. Dengan demikian, maka hipotesis teruji kebenarannya dan dapat diterima

Evaluation of cephalometric, hormonal and enzymatic parameters in young obese subjects

Aim The aim of the present investigation was to analyse cephalometric skeletal structures and hormonal and enzymatic parameters in young obese subjects in comparison with those of normal weight subjects. Materials and methods The whole sample consisted of 50 Caucasian patients (28 males and 22 females) whose lateral radiographs, laboratory hormonal and enzymatic analyses were already available. The test group included 25 obese patients (11 females and 14 males, average age: 9.8 ± 2.11 years old), while the control group included 25 normal weight subjects matched for age and sex (11 females and 14 males, 9.9 ± 2.5 years old). Data were statistically analysed: Student’s t-test for independent samples was adopted and the level of significance was set at: p< 0.05. Results As regards cephalometric records, the anterior cranial base length was significantly greater in the test group (S-N: 69.9 ± 4 mm) compared to the controls (S-N: 68.1 ± 2.7 mm). Moreover, the maxillary lenght was higher in the test group (Pm-A: 48.5 ± 2.5 mm ) in comparison to the control group (Pm-A: 46.1 ± 1.9 mm). As regards skeletal class and vertical dimension, no significant differences were found between the two groups, with the exception of the intermaxillary plane angle, which was significantly lower in the obese subjects in comparison to the controls. Laboratory analysis showed significant (p <0.05) higher levels of leptin and insulin in the test group in comparison with control subjects. Furthermore, LH, FSH, IGF-1 values were significantly (p <0.05) lower in the test group in comparison with the control group. Conclusion Obese subjects exhibited an increase of some craniofacial parameters and alteration of some laboratory parameters that may be involved in the process of skeletal maturation, in comparison to normal weight subjects. These findings may be of interest in orthodontics, as young obese subjects may need a different orthodontic treatment plan in comparison to Evaluation normal weight subjects of the same age

Molecular modeling of the interface of an egg yolk protein-based emulsion

Many food emulsions are stabilized by functional egg yolk biomolecules, which act as surfactants at the oil/water interface. Detailed experimental studies on egg yolk emulsifying properties have been largely hindered due to the difficulty in isolating individual chemical species. Therefore, this work presents a molecular model of an oil/water interfacial system where the emulsifier is one of the most surface-active proteins from the egg yolk low-density lipoproteins (LDL), the so-called Apovitellenin I. Dissipative particle dynamics (DPD) was here adopted in order to simulate large systems over long time scales, when compared with full-atom molecular dynamics (MD). Instead of a manual assignment of the DPD simulation parameters, a fully automated coarse-graining procedure was employed. The molecular interactions used in the DPD system were determined by means of a parameter calibration based on matching structural data from atomistic MD simulations. Despite the little availability of experimental data, the model was designed to test the most relevant physical properties of the protein investigated. Protein structural and dynamics properties obtained via MD and DPD were compared highlighting advantages and limits of each molecular technique. Promising results were achieved from DPD simulations of the oil/water interface. The proposed model was able to properly describe the protein surfactant behavior in terms of interfacial tension decrease at increasing protein surface concentration. Moreover, the adsorption time of a free protein molecule was estimated and, finally, an LDL-like particle adsorption mechanism was qualitatively reproduced