Electroless ultrasonic functionalization of diamond nanoparticles using aryl diazonium salts

We report a novel and very handful strategy for the functionalization of diamond nanoparticles (NDs), based on the ultrasound-assisted grafting of aryl groups from the electroless reduction of diazonium salts. For this study, 4-nitrobenzenediazonium salt was used as a model molecule and the reaction was investigated in neutral and acidic aqueous media. Spectroscopic evidence for the successful attachment of aryl groups to nanodiamonds (NDs) was given by IR and XPS which clearly detect characteristic NO₂ peaks. Moreover, the absence of any peaks from the ⁺N≡N group in the IR spectra is a clear indication of the chemical reduction of the parent diazonium salt at the surface of NDs. This spontaneous chemical modification of NDs by aryl diazonium salts was confined to the surface of the ND particles; indeed, XRD measurements have shown that the crystalline structure of the bulk of the particles was unaffected. It opens up new possibilities towards the control of the surface chemical composition of NDs using simple protocols operated in very soft conditions, i.e. in water at room temperature. It shows conclusively that the chemistry toolbox of experts interested in nanodiamonds should contain aryl diazonium salts, given their versatility in forming active platforms.     

Olfactory Responses to Aphid and Host Plant Volatile Releases: (E)-β-Farnesene an Effective Kairomone for the Predator Adalia bipunctata

The volatiles released from several aphid and host plant species, alone or associated, were studied for their infochemical role in prey location. Using a four-arm olfactometer, the attraction of several combinations of three aphid (Myzus persicae, Acyrthosiphon pisum, and Brevicoryne brassicae) and three plant (Vicia faba, Brassica napus, and Sinapis alba) species toward Adalia bipunctata larvae and adults was observed. Both predatory larvae and adults were attracted only by A. pisum and M. persicae when they were crushed, whatever the host plant. (E)-beta-farnesene, the aphid alarm pheromone, was the effective kairomone for the ladybird. Plant leaves alone (V. faba, B. napus, and S. alba) or in association with nonstressed whole aphids (the three species) did not have any attraction for the predator. The B. brassicae specialist aphid is the only prey that was not attracted to A. bipunctata larvae and adults, even if they were crushed. Release of B. brassicae molecules similar to the host plant allelochemicals was demonstrated by GC-MS analysis. The lack of behavioral response of the ladybird at short distance toward the cruciferous specialist aphid was related only to the absence of (E)-beta-farnesene in the aphid prey volatile pattern.     

Antimicrobial materials based on poly(ethylene-co-vinyl alcohol) and silver acetate produced by reactive extrusion

The use of silver as an antimicrobial agent has exhibited great interest in recent years. In this research, poly(ethylene-co-vinyl alcohol) (EVOH)–silver acetate-based antimicrobial materials were prepared at high temperature by reactive extrusion. Silver acetates were used without pretreatment. The thermal reaction of silver acetates in the material and their effect on the thermal and mechanical properties of the polymer were investigated as a function of their concentration. The dispersed silver acetate salts within the EVOH matrix have displayed a significant thermal reaction. This reaction of metallic salts was partial when the extrusion temperature was fixed at 190 °C and completed at 230 °C. The antimicrobial agents also had significant effects on the properties of the matrix. Reductions of glass temperature and storage modulus were observed by the analyses. All the variations were dependent on both the concentration of silver acetate and the extrusion parameters. The antimicrobial activity was studied and demonstrated a promising potential to create an antimicrobial material in a one-step solvent free extrusion method. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47799.     

Integration of Ultrafiltration Unit Operations in Biotechnology Process Design

A stepwise process design approach is proposed to model membrane unit operations generally in combination with experimental model parameter determination in laboratory scale, in order to predict the purification performance a priori by simulations for multicomponent mixtures. The development of a rigorous model for an ultrafiltration membrane is described. In conceptual process design, the degree of comprehension of all unit operations integrated have to be almost identical to be able of any consistent process proposal taking equipment‐related fluid‐dynamical and kinetic nonidealities besides thermodynamical feasibility into account. Therefore, a process model, combining the most limiting factors within one mathematical model, is established and various filtrations are carried out with a binary solution for validation. Additionally, a standard laboratory equipment is instituted for logging time‐dependent concentration profiles. The practicability of the proposed procedure is proven in order to design and integrate ultrafiltration membranes into total purification processes.     

Long term stability of electrocaloric response in barium zirconate titanate

The stability of the electrocaloric effect under electric field cycling is an important consideration in the development of solid-state cooling devices. Here we report measurements carried out on Ba(Zr_0.2Ti_0.8)O₃ ceramics which reveal that the adiabatic temperature change, polarization-electric field hysteresis loops and dielectric permittivity/loss show stable behavior up to 10⁵ cycles. We further demonstrate that the loss in electrocaloric response observed after 10⁵ cycles is associated with the migration of oxygen vacancies. As a result, the electrical properties of the material are changed leading to an increase in leakage current and Joule heating. Reversing the polarity of the electric field after every 10⁵ cycles changes the migration direction of oxygen vacancies, thereby preventing charge accumulation at grain boundaries and electrodes. By doing so, the electrocaloric stability is improved and the adiabatic temperature remains constant even after 10⁶ cycles, much higher than achieved in commercially available barium titanate ceramics.     

Immiscible Blends of PC and PET,Current Knowledge and New Results: Rheological Properties

This paper deals with immiscible blends of poly(ethylene terephthalate) obtained by melt blending with polycarbonate. A large survey of the current knowledge in the field of these blends is presented. Resolved and unresolved issues concerning the effect of exchange reactions on the miscibility of the components are addressed. The experimental part of the paper focuses on the rheological behavior of PET/PC blends. Blends containing various polymer ratios were obtained by melt blending with and without transesterification catalysts. Oscillatory shear flow in the melt was used to characterize the rheology of the various samples. A plot of the oscillatory data, similar to the Van Gurp Palmen plot, is used to point out the broadening of the co‐continuity window when in situ compatibilization takes place.

     

Stabilizing and destabilizing effects of drug-excipient interactions in spray-dried,freeze-dried,and granulated Sennae fructus extracts

Abstract

The objective of this study was to compare spray-dried and freeze-dried extracts of Sennae fructus regarding the stability of the sennosides. Therefore, the influence of the addition of maltodextrin (MD) not only before the drying processes but also during fluidized bed granulation was investigated. Analysis of the hygroscopicities, the simultaneous TGA-DSC-MS data, and the influence of storage revealed that spray-dried extracts are more stable than freeze-dried extracts. The addition of MD led to an even better stability of the extracts. Lower amounts of MD are sufficient if applied onto the surface of the native extract during fluidized bed granulation.     

MA‐NOTMP: A Triazacyclononane Trimethylphosphinate Based Bifunctional Chelator for Gallium Radiolabelling of Biomolecules

In the past few years, gallium‐68 has demonstrated significant potential as a radioisotope for positron emission tomography (PET), and the optimization of chelators for gallium coordination is a major goal in the development of radiopharmaceuticals. Methylaminotriazacyclononane trimethylphosphinate (MA‐NOTMP), a new C‐functionalized triazacyclononane derivative with phosphinate pendant arms, presents excellent coordination properties for ⁶⁸Ga (low ligand concentration, labelling at low pH even at room temperature). A “ready‐to‐be‐grafted” bifunctional chelating agent (p‐NCS‐Bz‐MA‐NOTMP) was prepared to allow ⁶⁸Ga labelling of sensitive biological vectors. Conjugation to a bombesin_(7–14) derivative was performed, and preliminary in vitro experiments demonstrated the potential of MA‐NOTMP in the development of radiopharmaceuticals. This new chelator is therefore of major interest for labelling sensitive biomolecules, and further in vivo experiments will soon be performed.     

Synthetic and Biological Studies of Sesquiterpene Polygodial: Activity of 9‐Epipolygodial against Drug‐Resistant Cancer Cells

Polygodial, a terpenoid dialdehyde isolated from Polygonum hydropiper L., is a known agonist of the transient receptor potential vanilloid 1 (TRPV1). In this investigation a series of polygodial analogues were prepared and investigated for TRPV1‐agonist and anticancer activities. These experiments led to the identification of 9‐epipolygodial, which has antiproliferative potency significantly exceeding that of polygodial. 9‐Epipolygodial was found to maintain potency against apoptosis‐resistant cancer cells as well as those displaying the multidrug‐resistant (MDR) phenotype. In addition, the chemical feasibility for the previously proposed mechanism of action of polygodial, involving the formation of a Paal–Knorr pyrrole with a lysine residue on the target protein, was demonstrated by the synthesis of a stable polygodial pyrrole derivative. These studies reveal rich chemical and biological properties associated with polygodial and its direct derivatives. These compounds should inspire further work in this area aimed at the development of new pharmacological agents, or the exploration of novel mechanisms of covalent modification of biological molecules with natural products.     

Strain‐induced deformation mechanisms of polylactide plasticized with acrylated poly(ethylene glycol) obtained by reactive extrusion

This work aimed at identifying the tensile deformation mechanisms of an original grade of plasticized polylactide (pPLA) obtained by reactive extrusion. This material had a glass transition temperature of 32.6 °C and consisted of a polylactide (PLA) matrix grafted with poly(acryl‐poly(ethylene glycol)) (poly(Acryl‐PEG)) inclusions. pPLA behaved like a rubber‐toughened amorphous polymer at 20 °C, and its tensile behavior evolved toward a rubbery semicrystalline polymer with increasing temperature. The drawing of pPLA involved orientation of amorphous and crystalline chains, crystallization, and destruction of crystals. It was found that crystal formation and crystal destruction were in competition below 50 °C, resulting in a constant or slightly decreasing crystallinity with strain. Increasing temperature enhanced crystal formation and limited crystal destruction, resulting in an increased crystallinity with the strain level. Drawing yielded a transformation of the initial spherical poly(Acryl‐PEG) inclusions into ellipsoids oriented in the tensile direction. This mechanism may engender the formation of nanovoids within the inclusions due to a decreased density, assumed to be responsible for the whitening of the specimen. © 2015 Society of Chemical Industry