Desorption characteristics of desiccant bed for solar dehumidification/humidification air conditioning systems

Theoretical and experimental investigation on the desorption characteristics of a packed porous bed is presented in this study. The granules of burned clay are applied as a desiccant carrier. Calcium chloride is used as the working desiccant. The theoretical model defines the transient gradient of air stream parameters (humidity and temperature) as well as desiccant concentration in the bed. In the experimental study, transient concentration gradient in the bed is evaluated by weight method. The bed is divided into seven separate layers. Air stream at low temperature and nearly constant inlet parameters are used for desorption purposes. Concentration gradient in the bed is found highly dependent on the mass transfer rate. For the specified operating conditions and stated assumptions, experimental measurements shows acceptable agreement with the analytical solution.     

The potential use of alkaline protease from Streptomyces albidoflavus as an eco-friendly wool modifier

The main task of this study is to search for the proper conditions of the enzymatic treatment using an alkaline bacterial protease, as an eco-friendly option, to improve some performance properties and dyeability of grey wool fabric with acid dyes. The efficiency of the enzymatic treatment has been improved by prewashing in the presence of a nonionic wetting agent alone and in combination with H₂O₂. The enhancement in wool performance properties as well as in the extent of post-acid dyeing is determined by pretreatment regime, enzyme dosage, as well as enzymatic treatment conditions. For modified wool fabric samples, as the weight loss increases, the nitrogen content decreases, the whiteness index as well as the dyeability with the acid dye improves compared with the prewashed fabric samples. Proper conditions for maximising the efficiency of enzymatic treatment along with attaining better performance properties and minimal wool damage are: prewashing in the presence of a nonionic surfactant along with H₂O₂ followed by enzymatic treatment using the enzyme dosage (3?ml/g fabric), pH (9), incubation time (45?min), temperature (40?°C), LR (1/20) and rotational speed (40?rpm). The enzyme inactivation was performed at 100?°C for 5?min, followed by thoroughly rinsing, neutralising and air-drying before testing. SEM images also provide evidence that pretreatment of the wool substrate enhanced the proteolysis of cuticle layers, their degradation and potential removal by the subsequent protease treatment.     

The 2-oxoglutarate-dependent oxygenase JMJD6 catalyses oxidation of lysine residues to give 5S-hydroxylysine residues

Amino acid analyses reveal that JMJD6-catalysed hydroxylation of RNA-splicing regulatory protein fragments occurs to give hydroxylysine products with 5S stereochemistry. This contrasts with collagen lysyl hydroxylases, which give 5R-hydroxylated products. The work suggests that more than one subfamily of lysyl hydroxylases has evolved and illustrates the importance of stereochemical assignments in proteomic analyses.     

Process Optimization,Physical Properties,and Environmental Stability of an α-Tocopherol Nanocapsule Preparation Using Complex Coacervation Method and Full Factorial Design

α-Tocopherol (α-Toc) has valuable biological activity, but its activity is limited when exposed to environmental factors. Nanocapsules can be used to overcome this problem. Using nanocapsules in the range of 100–200 nm is more beneficial. A 2⁴ full factorial design was carried out to optimize the size of nanocapsules using the complex coacervation method. The four factors were the amount of the wall material, the ratio of core material to wall material, the pH of the solution, and the speed of the homogenizer. The smallest nanocapsules (176 nm) were obtained at a wall content (gelatine and pectin) of 0.8 mg, a percentage of core material (α-Toc) to wall material of 20%, a pH = 4.5, and a homogenizer speed of 12,000 rpm. The encapsulation efficiency was 90.6 ± 1.1%, and the encapsulation yield was 83.4 ± 1.6%. Assessment of the stability of α-Toc after 1 month showed that encapsulation could improve its stability in the presence of three influential factors: humidity, light, and temperature.     

Modeling and Management of Firewall Policies

Firewalls are core elements in network security. However, managing firewall rules, especially for enterprise networks, has become complex and error-prone. Firewall filtering rules have to be carefully written and organized in order to correctly implement the security policy. In addition, inserting or modifying a filtering rule requires thorough analysis of the relationship between this rule and other rules in order to determine the proper order of this rule and commit the updates. In this paper we present a set of techniques and algorithms that provide automatic discovery of firewall policy anomalies to reveal rule conflicts and potential problems in legacy firewalls, and anomaly-free policy editing for rule insertion, removal, and modification. This is implemented in a user-friendly tool called ?Firewall Policy Advisor.? The Firewall Policy Advisor significantly simplifies the management of any generic firewall policy written as filtering rules, while minimizing network vulnerability due to firewall rule misconfiguration.     

ADHESION OF ELASTOMERS: DWELL TIME EFFECTS

The strength of adhesion of elastomers to rigid substrates generally increases with time of contact. This effect has been studied for samples of butyl and chlorobutyl rubber adhering to some rigid substrates. The peel strength increased continuously over long periods of contact until in some cases failure became cohesive within the elastomer layer. At higher temperatures the strength increased more rapidly, consistent with the WLF relation governing molecular motions. It is postulated that slow molecular rearrangements occur at the interface and increase the bond strength. A criterion for the observed transition from interfacial to cohesive failure is suggested.     

An Application of Computer‐Aided Molecular Design (CAMD) Using the Signature Molecular Descriptor–Part 2. Evaluating Newly Identified Surface Tension‐Reducing Substances for Potential Use as Shrinkage‐Reducing Admixtures

In this study, the use of computer‐aided molecular design (CAMD) is validated as a tool for enabling the discovery of new shrinkage‐reducing compounds for possible use in portland cement composites and is framed as one of many multiscale modeling tools in a broad hierarchy of possibilities. Twelve additives were tested for their ability to inhibit shrinkage in Type I ordinary portland cement under both autogenous and drying conditions. The 12 additives included two commercial shrinkage‐reducing admixtures (SRAs), two active ingredients of a commercial admixture [one of which was used to establish the quantitative structure–property relationships (QSPR)], two additional classified as potential SRA compounds based on the patent literature, four newly identified compounds predicted by using CAMD and an inverse quantitative structure–property relationship (I‐QSPR), and two other compounds use to establish the QSPR relationship. The newly identified I‐QSPR compounds were targeted for their ability to reduce the surface tension of water, a primary consideration for shrinkage‐reducing activity. Results for both drying shrinkage and autogenous shrinkage indicate that the designed compounds perform similar to commercial admixtures, yet have different chemical functionalities. Hydration data and set measurements were also considered since selection of new SRAs is a multiparameter problem with many constraints. Thus, these newly identified shrinkage‐reducing compounds can potentially provide additional options for use in portland cement concrete applications.     

Crosslinking of ethylene propylene diene monomer (EPDM) by buckminsterfullerene

An EPDM (ethylene-propylene-ethylidene norbornene terpolymer) rubber has been dissolved in o-dichlorobenzene with 1 phr of C₆₀. When cast onto a glass slide and dried, an insoluble film exhibiting reversible elasticity forms. Received: 10 December 1996/Revised: 13 January 1997/Accepted: 17 January 1997     

A modified thermodynamic insight to deliquescence of a void‐containing nanocrystal confirmed by MD simulation

Existence of voids in crystalline structures can affect their physical and chemical properties considerably. When the size of the crystal reaches to nanoscale, experimental determination of its void fraction is difficult. In this work, a molecular dynamics approach is introduced to find equilibrium void fractions of a simple cubic (CsCl) and fcc (KCl) nanocrystals by determination of their deliquescence relative humidity (DRH) for different sizes and void fractions and extrapolation of the results to the bulk limit. To confirm the simulation results, the size dependency of DRH to the nanoparticle size was studied thermodynamically by inclusion of size‐dependent density of water nanodroplet which leads to a simple homographic equation. This method proposes the equilibrium void percents of CsCl and KCl nanoparticles to be 10 and 15%, respectively, which are obtained by extrapolation of the results to the bulk limit. The success of obtained Möbius function was also confirmed by fitting it to experimental data for deliquescence of NaCl nanoparticles which implies the importance of considering density of water nanodroplet as a size dependent quantity. Also, using the mentioned thermodynamic approach, void dependency of deliquescence for the nanoparticles was found to be as a quasi‐linear trend which is compatible with the simulation results. It is noticeable that the approach used this work for determination of equilibrium void fraction is only valid if the utilized force fields are accurate. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4066–4077, 2016     

Graphene nanoplatelets dispersion in poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactic acid): preparation method and its influence on electrical,crystallinity and thermomechanical properties

Poly(l-lactic acid) (PLLA)/graphene nanoplatelets (GnP) nanocomposites were prepared through solvent casting and coagulation methods. The better dispersion of graphene was achieved by ultrasounds and its effect on crystallinity, thermomechanical and electrical properties of PLLA were studied and compared in both methods. Differential scanning calorimetry (DSC) was used to investigate the crystallinity of PLLA and its composites. Field emission gun scanning electron microscope (FEG-SEM) and wide-angle X-ray scattering (WAXS) were employed to characterize the microstructure of PLLA crystallites. Dynamic mechanical thermal analysis (DMTA) was performed to study the thermomechanical properties of the nanocomposites. FEG-SEM images illustrated finer dispersion of GnP in samples obtained by coagulation method with respect to solvent casting method. Graphene imparted higher electrical conductivity to nanocomposites obtained by solvent casting under ultrasound due to better formation of graphene network. DSC thermograms and their resulting data showed positive effects of GnP on crystallization kinetics of PLLA in both methods enhanced by the nucleating effect of graphene particles. Meanwhile, the effect of GnP, as nucleating agent, was more prominent in samples produced by coagulation method without utilization of ultrasounds. WAXS patterns represented the same characteristic peaks of PLLA in nanocomposite specimens suggesting similar crystalline structure of PLLA in presence of graphene, and the intensified peaks of nanocomposites compared to neat PLLA confirmed the DSC results regarding its improved crystallinity. Graphene increased storage modulus in rubbery region and glass transition temperature of nanocomposites in the coagulation method due to restricted mobility of PLLA chains.