A Plant-inspired Light Transducer for High-performance Near-infrared Light Mediated Gas Sensing

Constructing near-infrared light (NIR) light-enhanced room temperature gas sensors is becoming more promising for practical application. In this study, learning from the structure and photosynthetic process of chlorophyll thylakoid membranes in plants, the first “Thylakoid membrane” structural formaldehyde (HCHO) sensor is constructed by matching the upconversion emission of the lanthanide-doped upconversion nanoparticles (UCNPs) and the UV–vis adsorption of the as-prepared nanocomposites. The NIR-mediated sensor exhibits excellent performances, including ultra-high response (R_a / R_g = 2.22, 1 ppm), low practical limit of detection (50 ppb), reliable repeatability, high selectivity, and broadband spectral response. The practicality of the NIR-mediated gas sensor is confirmed through the remote and external stimulation test. A study of sensing mechanism demonstrates that it is the UCNPs-based light transducer produces more light-induced oxygen species for gas response in the process of non-radiative/radiative energy transfer, playing a key role in significantly improving the sensing properties of the sensor. The universality of NIR-mediated gas sensors based on UCNPs is verified using ZnO, In₂O_3, and SnO₂ systems. This work paves a way for fabricating high-performance NIR-mediated gas sensors and will expand the application fields of NIR light.     

Status quo and future research challenges on organic food quality determination with focus on laboratory methods

Organic food quality determination needs multi‐dimensional evaluation tools. The main focus is on the authentication as an analytical verification of the certification process. New fingerprinting approaches such as ultra‐performance liquid chromatography–mass spectrometry, gas chromatography–mass spectrometry, direct analysis in real time–high‐resolution mass spectrometry as well as crystallization with and without the presence of additives seem to be promising methods in terms of time of analysis and detecting organic system‐related parameters. For further methodological development, a system approach is recommended, which also takes into account food structure aspects. Furthermore, the authentication of processed organic samples needs more consciousness, hence most of organic food is complex and processed. © 2013 Society of Chemical Industry     

A high-throughput cheese manufacturing model for effective cheese starter culture screening

Cheese making is a process in which enzymatic coagulation of milk is followed by protein separation, carbohydrate removal, and an extended bacterial fermentation. The number of variables in this complex process that influence cheese quality is so large that the developments of new manufacturing protocols are cumbersome. To reduce screening costs, several models have been developed to miniaturize the cheese manufacturing process. However, these models are not able to accommodate the throughputs required for systematic screening programs. Here, we describe a protocol that allows the parallel manufacturing of approximately 600 cheeses in individual cheese vats each with individual process specifications. Protocols for the production of miniaturized Gouda- and Cheddar-type cheeses have been developed. Starting with as little as 1.7 mL of milk, miniature cheeses of about 170 mg can be produced and they closely resemble conventionally produced cheese in terms of acidification profiles, moisture and salt contents, proteolysis, flavor profiles, and microstructure. Flavor profiling of miniature cheeses manufactured with and without mixed-strain adjunct starter cultures allowed the distinguishing of the different cheeses. Moreover, single-strain adjunct starter cultures engineered to overexpress important flavor-related enzymes revealed effects similar to those described in industrial cheese. Benchmarking against industrial cheese produced from the same raw materials established a good correlation between their proteolytic degradation products and their flavor profiles. These miniature cheeses, referred to as microcheeses, open new possibilities to study many aspects of cheese production, which will not only accelerate product development but also allow a more systematic approach to investigate the complex biochemistry and microbiology of cheese making.     

First tests of standardized biocrystallization on milk and milk products

The biocrystallization method has been standardized for plant products. The standardized biocrystallization method is tested on milk and butter samples from controlled feeding trials. When computerized image analysis is applied, samples from different origins (feeding regimes) can be distinguished significantly.     

Break-up of a set of liquid threads under influence of surface tension

In this paper it is shown how the long-standing problem of the break-up of a cylindrical interface due to surface tension can be generalized to an arbitrary number of interacting interfaces in an arbitrary configuration. A system of immersed threads starting with two types of configurations is studied, i.e., a system of threads on a row and a system of threads at triangular vertices. From these cases, which are worked out in detail, it becomes clear how the stability of an arbitrary configuration can be determined. The (in)stability of the configuration is discussed in terms of the so-called disturbance growth rate. It turns out that the threads break up in specific phase patterns in which neighbouring threads are either in-phase or out-of-phase. For L threads, in principle 2^L phase patterns are possible. However, it is shown that the stability of the system directly follows from L so-called basic phase patterns. Special attention is paid to the special case of threads and fluid having equal viscosity. Then, the growth rate can be calculated analytically using Hankel transformations. An estimate for the growth rate in this case, which turns out to be quite sharp, is derived.     

Design of a multilayer transducer for acoustic bladder volume assessment

Catheterization remains the "gold standard" for bladder volume assessment, but it is invasive and introduces the risk of infections and traumas. Therefore, noninvasive bladder volume measurement methods have gained interest. In a preceding study a new technique to measure the bladder volume on the basis of nonlinear ultrasound wave propagation was validated. This paper describes a first prototype of a dedicated multilayer transducer to implement this approach. It is composed of a PZT transducer for transmission and a PVDF layer for reception. Acoustical measurements in a water tank and phantom measurements showed that there is a relation between bladder volume and the harmonic contents of the echo obtained from a region of interest behind the bladder. Simulations with an equivalent transducer model on the basis of KLM-circuit modeling closely matched with the results from the acoustical measurements. The results demonstrated the feasibility of the multilayer transducer design for bladder volume assessment on the basis of nonlinear wave propagation.     

Design and fabrication of nanofluidic devices by surface micromachining

Using surface micromachining technology, we fabricated nanofluidic devices with channels down to 10?nm deep, 200?nm wide and up to 8?cm long. We demonstrated that different materials, such as silicon nitride, polysilicon and silicon dioxide, combined with variations of the fabrication procedure, could be used to make channels both on silicon and glass substrates. Critical channel design parameters were also examined. With the channels as the basis, we integrated equivalent elements which are found on micro total analysis (μTAS) chips for electrokinetic separations. On-chip platinum electrodes enabled electrokinetic liquid actuation. Micro-moulded polydimethylsiloxane (PDMS) structures bonded to the devices served as liquid reservoirs for buffers and sample. Ionic conductance measurements showed Ohmic behaviour at ion concentrations above 10?mM, and surface charge governed ion transport below 5?mM. Low device to device conductance variation (1%) indicated excellent channel uniformity on the wafer level. As proof of concept, we demonstrated electrokinetic injections using an injection cross with volume below 50?attolitres (10(-18)?l).     

Characteristics of two-component epoxy modified bitumen

Coal tar bearing emulsions were used in the Netherlands as binder in anti-skid surfaces for runways because of their perfect adhesion and fuel resistance properties. They are however toxic and will not be allowed anymore after 2010. Therefore alternatives need to be developed. As one of the alternatives, two types of two-component epoxy modified bitumen have been investigated by means of direct tensile tests (DTT), relaxation tests (RT) and dynamic shear rheometer (DSR) tests. The effect of the curing temperature on the strength development of the epoxy modified bitumen was tested. The results show that the tensile strength increases with increasing curing time and temperature. DTT and RT results indicate that this new epoxy modified bitumen has a much higher tensile strength, cures faster than a bitumen emulsion as a binder. Furthermore, it shows a good stress relaxation even at lower temperatures. The curing speed and the ultimate tensile strength after full curing can be easily adjusted. The DSR results show that the complex modulus of this epoxy modified binder is less susceptible to changes in temperature. The results also suggest that this epoxy modified bitumen has better anti-crack properties at lower temperature and less permanent deformation than bituminous binders at higher temperatures. All these results shows that this type of two-component epoxy modified bitumen can be promising as a binder in anti-skid layers.