Antti Meriläinen

Simultaneous X-ray diffraction and X-ray fluorescence microanalysis on secondary xylem of Norway spruce

Secondary xylem of Norway spruce was studied by X-ray microanalysis. Average dimensions of cellulose crystallites, fraction of oriented cellulose, mean microfibril angle, and nutrient element concentrations of K, Ca, Mn, and Zn were simultaneously determined using microfocused synchrotron radiation and a combination of X-ray diffraction and X-ray fluorescence spectroscopy techniques. The variation of these quantities in the microscopic size scale was noticeable, and similar between samples taken from the same annual ring. The mean microfibril angle and the nutrient concentrations of Ca, Mn, and Zn showed a correlation. The mean values of the structural parameters and their variation as a function of the annual ring were similar as reported in previous studies on Norway spruce.

Controlled Expansion of Supercritical Solution: A Robust Method to Produce Pure Drug Nanoparticles With Narrow Size-Distribution.

We introduce a robust, stable, and reproducible method to produce nanoparticles based on expansion of supercritical solutions using carbon dioxide as a solvent. The method, controlled expansion of supercritical solution (CESS), uses controlled mass transfer, flow, pressure reduction, and particle collection in dry ice. CESS offers control over the crystallization process as the pressure in the system is reduced according to a specific profile. Particle formation takes place before the exit nozzle, and condensation is the main mechanism for postnucleation particle growth. A 2-step gradient pressure reduction is used to prevent Mach disk formation and particle growth by coagulation. Controlled particle growth keeps the production process stable. With CESS, we produced piroxicam nanoparticles, 60 mg/h, featuring narrow size distribution (176 ± 53 nm).

Detecting lane departures from steering wheel signal

Current lane departure warning systems are video-based and lose data when road- and weather conditions are bad. This study sought to develop a lane departure warning algorithm based on the signal drawn from the steering wheel. The rationale is that a car-based lane departure warning system should be robust regardless of road- and weather conditions. N=34 professional driver students drove in a high-fidelity driving simulator at 80km/h for 55min every third hour during 36h of sustained wakefulness. During each driving session we logged the steering wheel- and lane position signals at 60Hz. To derive the lane position signal, we quantified the transfer function of the simulated vehicle and used it to derive the absolute lane position signal from the steering wheel signal. The Pearson correlation between the derived- and actual lane position signals was r=0.48 (based on 12,000km). Next we designed an algorithm that alerted, up to three seconds before they occurred, about upcoming lane deviations that exceeded 0.2m. The sensitivity of the algorithm was 47% and the specificity was 71%. To our knowledge this exceeds the performance of the current video-based systems.

REAL‐TIME NONDESTRUCTIVE CONTACT RESISTANCE METHOD TO ESTIMATE WIRE BOND PULL FORCE

We estimate microelectronic wire bond quality nondestructively by measuring the contact resistance (CR) of the bond in situ during the bonding process. This measurement employs a Kelvin cross setup contacting the wedge, 25 um Al wire and an Au substrate. The results verify that the method can identify the bond process phases and predict whether the bonding was successful (94% classification accuracy). The method can be used for process control and optimization to create stronger bonds and higher yield.

2D-5 Combining X-Rays and Ultrasound to Determine Micro-Elasticity

We continue our quest to determine localized micro- elasticity by combining a standing ultrasonic wave pattern and SAXS X-ray diffraction (CuKalpha 1.54 Aring) to map the local elastic modulus. This was done in 20times20times1.5 mm3 dry Scots pine (Pinus Sylvestris L) soft wood and high-density polyethene (HDPE), acting as homogenized wood phantom samples. An Atmel Atmega 8515 (8 bit, 16 MHz) microprocessor launches and upholds a resonant lambda/2 wave pattern in the radial wood direction using a 100 Hz feedback loop. By varying the transmitted ultrasonic power, it is possible to alter the local stress within the volume probed by the 1 mm2 X-ray beam. The local strain in unit crystals is determined from changes in the width and position of the X-ray diffraction peaks. The results indicate that the method is applicable for localized quantitative elasticity mapping.