The influence of counter-ion adsorption on the ψ0/pH characteristics of insulator surfaces

The site-binding theory of Yates, Levine, and Healy is extended to include the possibility that counter-ion binding of anions and cations occurs at different distances from the insulator surface. A method for straightforward computation of the ψ0/σ0/pH characteristics is given. This theory is applied to the study of electrolyte/insulator/silicon structures, which makes it possible to measure the ψ0/pH characteristics. Measurements are presented for structures where the insulator is γ-Al2O3 deposited by chemical vapour deposition at 900°C. The influence of counter-ion binding on the ψ0/pH curves is a second-order effect compared to the site-dissociation acid/base reactions, but it is clearly visible. Consideration of the influence of the ionic strength of the electrolyte leads to an estimated anion adsorption equilibrium constant in the range of 0.05 to 0.4 mol−1 dm3 in chloride solutions, although no significant influence of the type of ions present could be observed. Application of the theory to existing measurements of the ψ0/pH and σ0/pH curves of SiO2 surfaces indicates that for this material the cation adsorption equilibrium constant is in the order of 0.1 mol−1 dm3

Surface-micromachined Ta–Si–N beams for use in micromechanics

Realization and characterization of free-standing surface-microstructures based on Ta-Si-N films are presented. Due to their significant physical and chemical properties, such ternary films are promising candidates for application in microelectromechanical devices

Inhibin reduces spermatogonial numbers in testes of adult mice and chinese hamsters

Bovine follicular fluid (bFF) injected ip in mice during 2 days (65,000 U inhibin/day, 1 U inhibin the activity in 1 /μg bFF protein) caused a significant decrease in the numbers of A4, intermediate (In), and B spermatogonia to 91%,74%, and 67% of the control values, respectively. The numbers of undifferentiated spermatogonia remained unchanged. These injections suppressed peripheral FSH levels to 6% of the control values, suggesting that FSH might be the modulator of the effects on spermatogenesis. However, in the Chinese hamster, intratesticular injections of bFF during 4 days (6500 U inhibin/day into one testis) also caused a significant decrease in the numbers of A3, In, B1, and B2 spermatogonia to 86%, 61%, 55%, and 94% of the control values, respectively. Similarly, treatment with a partially purified inhibin preparation from rat Sertoli cell-conditioned medium (rSCCM) during 4 days (Mono Q fraction; 1512 U inhibin/day; 37.8 μg protein) caused a significant decrease in the numbers of A3, In, B1, and B2 spermatogonia to 90%, 87%, 66%, and 93% of the control values, respectively. Treatment with a highly purified inhibin preparation from rSCCM during 4 days (30K inhibin; 750 U inhibin/day; 100 ng protein) significantly decreased the numbers of In and B1 spermatogonia to, respectively, 87% and 91% of the control values. These effects were limited to the testis into which the material was injected; the contralateral testis or testes injected with control fluid always showed normal numbers of spermatogonia. This implies that the effects on the seminiferous epithelium are not FSH mediated. Intratesticular injections of bFF or pure inhibin did not affect the number of undifferentiated spermatogonia. However, the Mono Q fraction caused a significant increase in the numbers of undifferentiated spermatogonia in stages IV-VII of the cycle, suggesting the presence of a mitogenic factor for undifferentiated spermatogonia in rSCCM which is not present or is counteracted in bFF. The results suggest that inhibin may have a role in the regulation of spermatogonial development in the adult animal

Spatially Controlled Membrane Depositions for Silicon-Based Sensors

The membrane deposition technology on silicon-based transducers constitutes the most delicate part of the miniaturized (bio)chemical sensor fabrication. Membrane adhesion to the transducer, reproducibility of the deposition process and its spatial control are the three most important parameters which determine the sensor performance and lifetime.The fabrication of two sensors is described: 1) a combined pO2, pCO2, pH sensor for which a polyacrylamide gel and a polysiloxane gas-permeable membrane were deposited and patterned at the on-wafer level and 2) a glucose amperometric enzyme electrode where the glucose oxidase was immobilized electrochemically either in a polypyrrole matrix or co-deposited with bovine serum albumin by electrochemically aided adsorption. The optimization of the deposition procedures allowed reproducible devices with reasonable lifetimes to be obtained

Sex differences in health-related quality of life and psychological distress among colorectal cancer patients:A 2-year longitudinal study

PurposeWhile sex differences in the incidence and mortality of colorectal cancer (CRC) are well documented, less is known about sex differences in patients’ health-related quality of life (HRQoL) and psychological distress. To enhance patient-tailored care, we aimed to longitudinally examine sex differences in HRQoL and psychological distress among CRC patients from diagnosis up until 2-year follow-up.MethodsNewly diagnosed CRC patients from four Dutch hospitals were eligible for participation. Patients (N = 334) completed questions on HRQoL (EORTC QLQ-C30) and psychological distress (HADS) before initial treatment (baseline), 4 weeks after surgery, and at 1 and 2 years after diagnosis. Also, HRQoL and psychological distress were assessed in a sex- and age-matched reference population.ResultsWhen directly comparing female (N = 126, 38%) and male (N = 208, 62%) CRC patients, female patients reported significantly worse HRQoL, such as more insomnia at baseline, worse physical and role functioning 4 weeks after surgery, more diarrhea at 1 year, and more pain and constipation at 2-year follow-up. However, a comparison with the reference population revealed larger differences between patients and reference in males than in females. For example, at 1- and 2-year follow-up, male patients reported significantly worse cognitive and social functioning, more insomnia, and more anxiety compared with a reference population.ConclusionsEspecially male CRC patients reported worse HRQoL and more psychological distress when compared with a reference population.Implications for cancer survivorsKnowledge of sex-specific differences in HRQoL and psychological distress among CRC patients may help healthcare providers anticipate and appropriately address patients’ unique healthcare needs

A micro gas preconcentrator with improved performance for pollution monitoring and explosives detection

International audienceThis paper presents the optimization of a micro gas preconcentrator based on a micro-channel in porous and non-porous silicon filled with an adequate adsorbent. This micro gas preconcentrator is both applicable in the fields of atmospheric pollution monitoring (Volatil organic compounds—VOCs) and explosives detection (nitroaromatic compounds). Different designs of micro-devices and adsorbent materials have been investigated since these two parameters are of importance in the performances of the micro-device. The optimization of the device and its operation were driven by its future application in outdoor environments. Parameters such as the preconcentration factor, cycle time and the influence of the humidity were considered along the optimization process. As a result of this study, a preconcentrator with a total cycle time of 10 min and the use of single wall carbon nanotubes (SWCNTs) as adsorbent exhibits a good preconcentration factor for VOCs with a limited influence of the humidity. The benefits of using porous silicon to modify the gas desorption kinetics are also investigated