Optimal Control of the Primary Drying Stage of Freeze Drying of Solutions in Vials Using Variational Calculus

The problem of operating freeze drying of pharmaceutical products in vials placed in trays of a freeze dryer to remove free water (in frozen state) at a minimum time was formulated as an optimal control problem. Two different types of freeze dryer designs were considered. In type I freeze dryer design, upper and lower plate temperatures were controlled together, while in type II freeze dryer design, upper and lower plate temperatures were controlled independently. The heat input to the material being dried and the drying chamber pressure were considered as control variables. Constraints were placed on the system state variables by the melting and scorch temperatures during primary drying stage. Necessary conditions of optimality for the primary drying stage of freeze drying process in vials are derived and presented. Furthermore, an approach for constructing the optimal control policies that would minimize the drying time for the primary drying stage was given. In order to analyze optimal control policy for the primary drying stage of the freeze-drying process in vials, a rigorous multi-dimensional unsteady state mathematical model was used. The theoretical approach presented in this work was applied in the freeze drying of skim milk. Significant reductions in the drying times of primary drying stage of freeze drying process in vials were obtained, as compared to the drying times obtained from conventional operational policies.     

Characterization of rheological properties of systems containing sugar substitutes and carrageenan

The effects of addition of κ-carrageenan to solutions containing 40% (w/w) sugar substitute on the rheological properties of these systems were investigated at 25 °C using a rotational viscometer at rotational speeds of 6, 12, 30, and 60 rev min⁻¹. The flow behaviour of the solutions was adequately described by the power law model with or without yield stress. The consistency index ( K ) and the flow behaviour index ( n ) were determined from shear stress vs. shear rate data. The flow parameters of the solutions depended on the carrageenan concentration. The apparent viscosities of the systems decreased with increasing shear rate, indicating pseudoplastic behaviour. The final carrageenan concentration was found to be an effective factor controlling the degree of sliminess of the model food systems studied.     

A capacitive threshold-logic gate

A dense and fast threshold-logic gate with a very high fan-in capacity is described. The gate performs sum-of-product and thresholding operations in an architecture comprising a poly-to-poly capacitor array and an inverter chain. The Boolean function performed by the gate is soft programmable. This is accomplished by adjusting the threshold with a dc voltage. Essentially, the operation is dynamic and thus, requires periodic reset. However, the gate can evaluate multiple input vectors in between two successive reset phases because evaluation is nondestructive. Asynchronous operation is, therefore, possible. The paper presents an electrical analysis of the gate, identifies its limitations, and describes a test chip containing four different gates of fan-in 30, 62, 127, and 255. Experimental results confirming proper functionality in all these gates are given, and applications in arithmetic and logic function blocks are described     

Microarchitectures for Managing Chip Revenues under Process Variations

As transistor feature sizes continue to shrink intothe sub-90nm range and beyond, the effects of process variationson critical path delay and chip yields have amplified. A commonconcept to remedy the effects of variation is speed-binning, bywhich chips from a single batch are rated by a discrete range offrequencies and sold at different prices. In this paper, we discussstrategies to modify the number of chips in different bins andhence enhance the profits obtained from them. Particularly, wepropose a scheme that introduces a small Substitute Cacheassociated with each cache way to replicate the data elementsthat will be stored in the high latency lines. Assuming a fixedpricing model, this method increases the revenue by as much as13.8% without any impact on the performance of the chips.     

The Role of Rigid Residues in Modulating TEM-1 β-Lactamase Function and Thermostability

The relationship between protein motions (i.e., dynamics) and enzymatic function has begun to be explored in β-lactamases as a way to advance our understanding of these proteins. In a recent study, we analyzed the dynamic profiles of TEM-1 (a ubiquitous class A β-lactamase) and several ancestrally reconstructed homologues. A chief finding of this work was that rigid residues that were allosterically coupled to the active site appeared to have profound effects on enzyme function, even when separated from the active site by many angstroms. In the present work, our aim was to further explore the implications of protein dynamics on β-lactamase function by altering the dynamic profile of TEM-1 using computational protein design methods. The Rosetta software suite was used to mutate amino acids surrounding either rigid residues that are highly coupled to the active site or to flexible residues with no apparent communication with the active site. Experimental characterization of ten designed proteins indicated that alteration of residues surrounding rigid, highly coupled residues, substantially affected both enzymatic activity and stability; in contrast, native-like activities and stabilities were maintained when flexible, uncoupled residues, were targeted. Our results provide additional insight into the structure-function relationship present in the TEM family of β-lactamases. Furthermore, the integration of computational protein design methods with analyses of protein dynamics represents a general approach that could be used to extend our understanding of the relationship between dynamics and function in other enzyme classes.     

Design of a Commercial Hybrid VTOL UAV System

For the last four decades Unmanned Air Vehicles (UAVs) have been extensively used for military operations that include tracking, surveillance, active engagement with weapons and airborne data acquisition. UAVs are also in demand commercially due to their advantages in comparison to manned vehicles. These advantages include lower manufacturing and operating costs, flexibility in configuration depending on customer request and not risking the pilot on demanding missions. Even though civilian UAVs currently constitute 3 % of the UAV market, it is estimated that their numbers will reach up to 10 % of the UAV market within the next 5 years. Most of the civilian UAV applications require UAVs that are capable of doing a wide range of different and complementary operations within a composite mission. These operations include taking off and landing from limited runway space, while traversing the operation region in considerable cruise speed for mobile tracking applications. This is in addition to being able traverse in low cruise speeds or being able to hover for stationary measurement and tracking. All of these complementary and but different operational capabilities point to a hybrid unmanned vehicle concept, namely the Vertical Take-Off and Landing (VTOL) UAVs. In addition, the desired UAV system needs to be cost-efficient while providing easy payload conversion for different civilian applications. In this paper, we review the preliminary design process of such a capable civilian UAV system, namely the TURAC VTOL UAV. TURAC UAV is aimed to have both vertical take-off and landing and Conventional Take-off and Landing (CTOL) capability. TURAC interchangeable payload pod and detachable wing (with potential different size variants) provides capability to perform different mission types, including long endurance and high cruise speed operations. In addition, the TURAC concept is to have two different variants. The TURAC A variant is an eco-friendly and low-noise fully electrical platform which includes 2 tilt electric motors in the front, and a fixed electric motor and ducted fan in the rear, where as the TURAC B variant is envisioned to use high energy density fuel cells for extended hovering time. In this paper, we provide the TURAC UAV’s iterative design and trade-off studies which also include detailed aerodynamic and structural configuration analysis. For the aerodynamic analysis, an in-house software including graphical user interface has been developed to calculate the aerodynamic forces and moments by using the Vortex Lattice Method (VLM). Computational Fluid Dynamics (CFD) studies are performed to determine the aerodynamic effects for various configurations For structural analysis, a Finite Element Model (FEM) of the TURAC has been prepared and its modal analysis is carried out. Maximum displacements and maximal principal stresses are calculated and used for streamlining a weight efficient fuselage design. Prototypes have been built to show success of the design at both hover and forward flight regime. In this paper, we also provide the flight management and autopilot architecture of the TURAC. The testing of the controller performance has been initiated with the prototype of TURAC. Current work focuses on the building of the full fight test prototype of the TURAC UAV and aerodynamic modeling of the transition flight.     

A case of split notochord syndrome: presence of dorsal enteric diverticulum adjacent to the dorsal enteric fistula

Like umblical enteric remnants (eg, umblical sinus and omphalomesenteric fistula), enteric remnants can be seen on the dorsal aspect of the body (dorsal enteric sinus, dorsal enteric fistula IDEF], dorsal enteric diverticulum) in conjunction with complete cleft of the vertebral column. Complete cleft of the vertebral column associated with gastrointestinal tract and central nervous system anomalies is known as "split notochord syndrome" (SNS). The authors present an unreported variant of SNS having dorsal enteric diverticulum adjacent to the DEF. The patient died 17 days after surgical repair.     

Electrokinetic and antibacterial properties of needle like‐TiO2/polyrhodanine core/shell hybrid nanostructures

The aim of this study was to fabricate needle like‐TiO₂/polyrhodanine nanostructures by polymerizing rhodanine monomer on the TiO₂ nanoparticles' surfaces and investigate their antibacterial activities. The structural, thermal, morphological, surface and electrical properties of non‐covalently functionalized nanoparticles were characterized by using FTIR, XPS, elemental analysis, TGA, XRD, SEM‐EDX, TEM, contact angle, and conductivity measurements. Characterization results confirmed the formation of needle like‐TiO₂/polyrhodanine (PRh) core/shell hybrid nanostructures. Alterations on the surface and electrokinetic properties of the materials were characterized by zeta (ζ)‐potential measurements with the presence of various salts and surfactants. The ζ‐potential of needle like‐TiO₂ was observed to increase from ?7.6 mV to +28.4 mV after forming a core/shell needle like‐TiO₂/PRh nanocomposite structure and with the presence of cetyltrimethyl ammonium bromide (CTAB) surfactant. Thereby colloidally more stable dispersions were formed. Antibacterial properties of needle like‐TiO₂/PRh were also tested against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli by various methods and they showed good antibacterial activity. The highest killing efficiency was determined for needle like‐TiO₂/PRh against E. coli by colony‐counting method as 0.95. TEM experiments also showed the immobilizations of the nanoparticles on E. coli and revealed the interactions between E. coli and the nanoparticles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41554.     

Flocculation of coal suspension with mono/dual polymer systems and contribution of Ca(II)/Mg(II) ions

In the experimental study carried out on mono-flocculation, anionic and especially non-ionic polymers strongly flocculated the coal suspension than cationic polymer. The dual-flocculation of the coal suspension with cationic and anionic polymer combination was also studied and the high performances of flocculation were also reached with dual-polymer approach. Furthermore, dual-polymer system required lower concentrations for the successful flocculation of coal particles. On the other hand, the pre-destabilization of the coal suspension with calcium and magnesium ions at particular pH and concentrations highly improved the flocculation of fine coal particles with these polymers.