Fabrication and Determination of Refractive Index Profile of the Planar Waveguides by Wedge Technique

Several planar waveguides have been fabricated. The waveguides have been polished for determination of their refractiveindex profiles (RIP) by wedge method. The RIP determined by inserting the sample in a Mach-Zehnder interferometer andapplying fringe analysis methods.     

E-Beam—a new transfer system for isolator technology

In every aseptic filling application, the sterile transfer of goods into the aseptic area is a challenge, and there are many different ways to do it.

With isolator technology a higher sterility assurance level (SAL) is achieved. This SAL is only as good as the weakest segment in the chain of manufacturing. The transfer of goods into and out of the isolator is one of these critical segments.

Today different techniques, some already well established, others still very new, are available on the market like: dry heat tunnel, autoclave, pulsed light, rapid transfer systems (RTP), H₂O₂ tunnel, UV light, etc. all these systems are either not applicable for continuous transfer, only good for heat-compatible materials like glass, or do not guarantee a 6 log spore reduction.

E-Beam opens new perspectives in this field. With E-beam technology it is possible to transfer heat-sensitive (plastic), pre-sterilised materials at high speed, continuously into an aseptic area.

E-Beam unifies three different technologies, that result in a very efficient and high-speed decontamination machine designed for the pharmaceutical industry. First, there is the electron beam that decontaminates the goods and an accurate shielding that protects the surrounding from this beam. Second, there is the conveyor system that guarantees the output and the correct exposure time underneath the beam. And third, there is the isolator interface to provide correct differential pressure and clean air inside the tunnel as well as the decontamination of the tunnel with H₂O₂ prior to production.

The E-beam is a low-energy electron beam, capable of decontaminating any kind of surface. It penetrates only a few micrometers into the material and therefore does not deform the packaging media.

Currently, machines are being built to transfer pre-sterilised syringes, packed in plastic tubs with a Tyvek cover into an aseptic filling isolator with the following data: decontamination efficiency of 10⁶ (6 log spore reduction), decontamination speed of 6 tubs (600 syringes) per minute.

This is just one of many applications for this new technology.     

Blue TiO2 nanotube arrays as semimetallic materials with enhanced photoelectrochemical activity towards water splitting

In the past years there has been a great interest in self-doped TiO₂ nanotubes (blue TiO₂ nanotubes) compared to undoped ones owing to their high carrier density and conductivity. In this study, blue TiO₂ nanotubes are investigated as photoanode materials for photoelectrochemical water splitting. Blue TiO₂ nanotubes were fabricated with enhanced photoresponse behavior through electrochemical cathodic polarization on undoped and annealed TiO₂ nanotubes. The annealing temperature of undoped TiO₂ nanotubes was tuned before cathodic polarization, revealing that annealing at 500 °C improved the photoresponse of the nanotubes significantly. Further optimization of the blue TiO₂ nanotubes was achieved by adjusting the cathodic polarization parameters. Blue TiO₂ nanotubes obtained at the potential of –1.4 V (vs. SCE) with a duration of 10 min exhibited twice more photocurrent response (0.39 mA cm^-2) compared to the undoped TiO₂ nanotube arrays (0.19 mA cm^-2). Oxygen vacancies formed through the cathodic polarization decreased charge recombination and enhanced charge transfer rate; therefore, a high photoelectrochemical activity under visible light irradiation could be achieved.     

Amplified Electrochemical DNA Sensor Based on Polyaniline Film and Gold Nanoparticles

In this work, an electrochemical DNA biosensor, based on a dual signal amplified strategy by employing a polyaniline film and gold nanoparticles as a sensor platform and enzyme‐linked as a label, for sensitive detection is presented. Firstly, polyaniline film and gold nanoparticles were progressively grown on graphite screen‐printed electrode surface via electropolymerization and electrochemical deposition, respectively. The sensor was characterized by scanning electron microscopy (SEM), cyclic voltammetry and impedance measurements. The polyaniline‐gold nanocomposite modified electrodes were firstly modified with a mixed monolayer of a 17‐mer thiol‐tethered DNA probe and a spacer thiol, 6‐mercapto‐1‐hexanol (MCH). An enzyme‐amplified detection scheme, based on the coupling of a streptavidin‐alkaline phosphatase conjugate and biotinylated target sequences was then applied. The enzyme catalyzed the hydrolysis of the electroinactive α‐naphthyl phosphate to α‐naphthol; this product is electroactive and has been detected by means of differential pulse voltammetry. In this way, the sensor coupled the unique electrical properties of polyaniline and gold nanoparticles (high surface area, fast heterogeneous electron transfer, chemical stability, and ease of miniaturisation) and enzymatic amplification. A linear response was obtained over a concentration range (0.2–10 nM). A detection limit of 0.1 nM was achieved.     

Convenient Synthesis of 14‐Aryl‐14‐H‐dibenzo[a,j]xanthenes Catalyzed by Acyclic Brønsted Acidic Ionic Liquid [H—NMP]+[HSO4]− under Microwave Irradiation

Efficient method for direct preparation of 14‐aryl‐14‐H‐dibenzo[a,j]xanthenes through condensation of β‐naphthol with various aromatic aldehydes in the presence of the catalytic amount of [H—NMP]⁺[HSO₄]^? under microwave irradiation was described. This method has the advantages such as; very easy reaction workup, absolute separation of catalyst from the reaction mixture and smooth recyclability of catalyst. In this reaction 14‐aryl‐14‐H‐dibenzo[a,j]xanthenes were obtained as desired products in excellent yields and short reaction times via green and one‐pot procedure.     

Surface modification of cellulose nanocrystal with chitosan oligosaccharide for drug delivery applications

A novel drug delivery system based on two of the most abundant natural biopolymers was developed by modifying the surface of oxidized cellulose nanocrystal (CNC) with chitosan oligosaccharide (CS_OS). First, the primary alcohol moieties of CNC were selectively oxidized to carboxyl groups using the 2,2,6,6-tetramethylpiperidine-1-oxyl radical catalyst. The amino groups of CS_OS were then reacted with carboxylic acid groups on oxidized CNC (CNC-OX) via the carbodiimide reaction using N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide as coupling agents. Successful grafting of CS_OS to CNC-OX was confirmed by infrared spectroscopy, thermogravimetry, potentiometric titration, and zeta potential measurements. The grafting resulted in a conversion of ~90 % carboxyl groups on CNC-OX and the degree of substitution was 0.26. CNC–CS_OS nanoparticles showed a binding efficiency of 21.5 % and a drug loading of 14 % w/w. A drug selective electrode was used to directly measure the concentration of procaine hydrochloride released from CNC–CS_OS particles. The in vitro drug release was studied at pH 8 and the nanoparticles revealed a fast release of up to 1 h, which can be used as biocompatible and biodegradable drug carriers for transdermal delivery applications.