Averaging level control to reduce off-spec material in a continuous pharmaceutical pilot plant

The judicious use of buffering capacity is important in the development of future continuous pharmaceutical manufacturing processes. The potential benefits are investigated of using optimal-averaging level control for tanks that have buffering capacity for a section of a continuous pharmaceutical pilot plant involving two crystallizers, a combined filtration and washing stage and a buffer tank. A closed-loop dynamic model is utilized to represent the experimental operation, with the relevant model parameters and initial conditions estimated from experimental data that contained a significant disturbance and a change in setpoint of a concentration control loop. The performance of conventional proportional-integral (PI) level controllers is compared with optimal-averaging level controllers. The aim is to reduce the production of off-spec material in a tubular reactor by minimizing the variations in the outlet flow rate of its upstream buffer tank. The results show a distinct difference in behavior, with the optimal-averaging level controllers strongly outperforming the PI controllers. In general, the results stress the importance of dynamic process modeling for the design of future continuous pharmaceutical processes

Hydrogen Sulfide Triggered Charge-Reversal Micelles for Cancer-Targeted Drug Delivery and Imaging

Currently, the development of polymeric micelles combining diagnosis and targeted therapy is theoretically and practically significant in cancer treatment. In addition, it has been reported that cancer cells can produce large amounts of hydrogen sulfide (H₂S) and their survival depends on the content of H₂S. In this study, a series of <i>N</i>-(2-hydroxyethyl)-4-azide-1,8-naphthalimide ended amphiphilic diblock copolymer poly­(2-hydroxyethyl methacrylate)-<i>block</i>-poly­(methyl methacrylate) (N₃-Nap-PHEMA-<i>b</i>-PMMA-N₃) micelles were prepared. Around cancer tissues, the N₃-Nap-PHEMA₄₅-<i>b</i>-PMMA₄₂-N₃ micelles exhibited dual characteristics of monitoring H₂S and H₂S triggered charge reversal with the reduction of the azido group. The surface charge of N₃-Nap-PHEMA₄₅-<i>b</i>-PMMA₄₂-N₃ micelles reversed from negative to positive after monitoring H₂S. With H₂S triggered charge reversal, the cellular uptake of DOX-loaded N₃-Nap-PHEMA₄₅-<i>b</i>-PMMA₄₂-N₃ micelles was effectively enhanced through electrostatic attraction mediated targeting, and a fast doxorubicin (DOX) release rate was observed. The MTT assay demonstrated that N₃-Nap-PHEMA₄₅-<i>b</i>-PMMA₄₂-N₃ micelles were biocompatible to HeLa cells, and DOX-loaded N₃-Nap-PHEMA₄₅-<i>b</i>-PMMA₄₂-N₃ micelles showed enhanced cytotoxicity in HeLa cells in the presence of H₂S. Furthermore, in vivo fluorescence imaging and biodistribution experiments revealed that DOX-loaded N₃-Nap-PHEMA₄₅-<i>b</i>-PMMA₄₂-N₃ micelles could provide good tumor imaging and accumulate in tumor tissue. Therefore, N₃-Nap-PHEMA₄₅-<i>b</i>-PMMA₄₂-N₃ micelles can be used as a promising platform for tumor diagnosis and therapy

Kinetic Modeling of Acetic Acid Hydrogenation to Ethanol over K‑Modified PtSn Catalyst Supported on Alumina

Experiments for acetic acid hydrogenation and catalyst characterizations were conducted to study the kinetics of hydrogenation and esterification over PtSn impregnated on Al₂O₃ catalyst (PtSn/Al₂O₃), K doped on PtSn/Al₂O₃ catalyst (K/PtSn/Al₂O₃), and PtSn impregnated on K/Al₂O₃ catalyst (PtSn/K/Al₂O₃). Kinetic parameters such as activation energy, dissociation enthalpy, and adsorption heat of elementary reaction for hydrogenation and esterification were determined on the basis of Langmuir–Hinshelwood model. After the addition of 0.5 wt % K to PtSn/Al₂O₃, activation energy of hydrogenation decreased from 20.8 to 11.5 kJ/mol and activation energy of esterification increased from 22.3 to 31.7 kJ/mol. The results of dissociation energy and adsorption heat reflect that K/PtSn/Al₂O₃ can improve spillover of hydrogen and desorption of ethanol. PtSn/K/Al₂O₃ had the opposite effect. Potassium also enhanced dissociation of C–OH bond to form more acetyl species. Good agreement was obtained upon comparison of the experimental and calculated data

La biofisica

Un vasto progetto che, prendendo le mosse da una nuova teoria del mondo della vita, dà nuove interpretazioni dell'uomo, del suo vivere, del suo pensare

Searching grid cells near <i>C</i>₅ in a counterclockwise direction.

<p>Searching grid cells near <i>C</i>₅ in a counterclockwise direction.</p

Accurate predictions for arriving at the target location <i>I</i>.

<p>Accurate predictions for arriving at the target location <i>I</i>.</p

Newly generated sensitive rules ratios change with <i>K</i> values for different incremental combinations.

<p>Newly generated sensitive rules ratios change with <i>K</i> values for different incremental combinations.</p