Characterization of Si/Si_(1-y)C_y superlattices grown by surfactant assisted molecular beam epitaxy

Si/Si_(0.97)C_(0.03) superlattices grown on Si(001) substrates by Sb surfactant assisted molecular beam epitaxy are characterized by in situ reflection high energy electron diffraction (RHEED), atomic force microscopy, transmission electron microscopy (TEM), and high resolution x‐ray diffraction. The RHEED shows that, in the absence of Sb, the growth front roughens during Si_(0.97)C_(0.03) growth and smooths during subsequent Si growth. In contrast, when Sb is present, the growth front remains smooth throughout the growth. This observation is confirmed by cross‐sectional TEM, which reveals that for samples grown without the use of Sb, the Si/Si_(0.97)C_(0.03) interfaces (Si_(0.97)C_(0.03) on Si) are much more abrupt than the Si_(0.97)C_(0.03)/Si interfaces. In the case of Sb assisted growth, there is no observable difference in abruptness between the two types of interfaces. Atomic force microscopy micrographs of the Si_(0.97)C_(0.03) surface reveal features that could be the source of the roughness observed by RHEED and TEM

Sb-surfactant-mediated growth of Si/Si1–yCy superlattices by molecular-beam epitaxy

Si/Si0.97C0.03 superlattices were grown on Si(001) substrates by molecular beam epitaxy (MBE) to study the use of Sb as a surfactant during Si1–yCy growth. In situ reflection high energy electron diffraction (RHEED) shows that while carbon easily disrupts the two-dimensional growth of homoepitaxial Si, such disruption is suppressed for layers grown on Sb-terminated Si(001) surfaces. Cross-sectional transmission electron microscopy (TEM) reveals that for samples grown without the use of Sb, the Si/Si0.97C0.03 interfaces (Si0.97C0.03 on Si) were much more abrupt than Si0.97C0.03/Si interfaces. In the case of Sb-mediated growth, differences in abruptness between the two types of interfaces were not readily observable

The event generator DECAY4 for simulation of double beta processes and decay of radioactive nuclei

The computer code DECAY4 is developed to generate initial energy, time and angular distributions of particles emitted in radioactive decays of nuclides and nuclear (atomic) deexcitations. Data for description of nuclear and atomic decay schemes are taken from the ENSDF and EADL database libraries. The examples of use of the DECAY4 code in several underground experiments are described.Comment: 8 pages, 1 fi

Metoprolol, fentanyl and stress response to microlaryngoscopy. Effects on arterial pressure, heart rate and plasma concentrations of catecholamines, ACTH and cortisol

Forty patients undergoing microlaryngoscopy were anaesthetized with thiopentone and nitrous oxide. Twenty patients received metoprolol 200 mg in a slow-release tablet once daily for 4 days up to, and including, the morning of operation, and lOmgi.v. shortly before induction of anaesthesia. The other patients received placebo tablets and physiological saline i. v., instead-Both groups of 20 patients were further subdivided, half of the patients receiving fentanyl 1.0-1.5mg during anaesthesia, the effect of which was antagonized by naloxone at the end of the procedure. The other patients received saline i.v. instead of fentanyl or naloxone. Metopropolol decreased heart rate and the general level of arterial pressure during anaesthesia, but did not affect the fluctuations in pressure. Arterial plasma noradrenaline concentrations during microjaryngoscopy were >nlmnr<-H by metoprolol, in comparison with placebo, the reverse being the case for cortisol concentrations. Fentanyl decreased arterial pressure and plasma ACTH and cortisol concentrations regardless of whether the patient had received metoprolol. Plasma adrenaline and noradrenaline concentrations were decreased by fentanyl in the patients receiving metoprolol

Deltagardriven forskning – Växtodlingsgruppen, resultat och utvärdering av arbetet under 1998 till 2001

Då arbetet i växtodlingsgruppen påbörjades var förväntningarna på deltagardriven forskning att den sammanlagda erfarenheten hos lantbrukare, forskare och rådgivare skulle bidra till utförandet av relevanta gårdsförsök. Lantbrukarna önskade dessutom sträva efter att öka och vidarebefordra den kunskap som fanns i gruppen, samt att få etablerade forskare att undersöka områden som praktikerna upplever som viktiga och svåra. Redan i initialskedet slog växtodlingsgruppen fast att arbeta för att gemensamt identifiera problem och använda relevanta forskningsmetoder på gårdsnivå. Syftet var att genom olika odlingsåtgärder kunna förbättra förutsättningarna för ekologisk växtodling. Ett mål var att finna effektiva metoder för optimal växtnäringstillförsel i ekologisk produktion på lerjordar i Mälardalen. För närvarande saknas bra underlag för hur kväveleveransen varierar under säsongen framförallt till stråsäd. Detta påverkar i sin tur både skördeutfall, proteinhalt, miljöbelastning och ekonomi. Ett annat mål var att kunna reglera ogräsförekomsten, främst kvickrot och tistel, på ett effektivt sätt i växtföljden. Motivationen för lantbrukarna har under projektets gång varit att främja det ekologiska lantbruket som helhet. Detta har möjliggjorts genom erfarenhetsutbyte på gruppträffar kombinerat med gårdsbesök där lantbrukarnas intressen och frågeställningar har varit drivande. Växtodlingsgruppen har på så vis initialt bidragit till ett lokalt utvecklingsarbete och en uppbyggnad av ökat kunnande inom ekologiskt växtodling