Thermal analysis of the vertical bridgman semiconductor crystal growth technique

The quality of semiconductor crystals grown by the vertical Bridgman technique is strongly influenced by the axial and radial variations of temperature within the charge. The relationship between the thermal parameters of the vertical Bridgman system and the thermal behavior of the charge are examined. Thermal models are developed which are capable of producing results expressable in analytical form and which can be used without recourse to extensive computer work for the preliminary thermal design of vertical Bridgman crystal growth systems. These models include the effects of thermal coupling between the furnace and the charge, charge translation rate, charge diameter, thickness and thermal conductivity of the confining crucible, thermal conductivity change and liberation of latent heat at the growth interface, and infinite charge length. The hot and cold zone regions, considered to be at spatially uniform temperatures, are separated by a gradient control region which provides added thermal design flexibility for controlling the temperature variations near the growth interface

Meson spectroscopy with COMPASS

The COMPASS fixed-target experiment at CERN SPS is dedicated to the study of hadron structure and dynamics. In the physics programme using hadron beams, the focus is on the detection of new states, in particular the search for $J^{PC}$ exotic states and glueballs. After a short pilot run in 2004 (190 GeV/c negative pion beam, lead target), we started our hadron spectroscopy programme in 2008 by collecting an unprecedented statistics with a negative hadron beam (190 GeV/c) on a liquid hydrogen target. A similar amount of data with positive hadron beam (190 GeV/c) has been taken in 2009, as well as some additional data with negative beam on nuclear targets. The spectrometer features a large angular acceptance and high momentum resolution and also good coverage by electromagnetic calorimetry, crucial for the detection of final states involving $\pi^0$ or $\eta$. A first important result is the observation of a significant $J^{PC}$ spin exotic signal consistent with the disputed $\pi_1(1600)$ in the pilot run data. This result was recently published. We present an overview of the status of various ongoing analyses on the 2008/09 data.Comment: 6 pages, 6 figures, to appear in the proceedings of the International Nuclear Physics Conference 2010, Vancouver, Canada, 04-09 Jul 201

Defects in p-GaN and their atomic structure

In this paper defects formed in p-doped GaN:Mg grown with Ga polarity will be discussed. The atomic structure of these characteristic defects (Mg-rich hexagonal pyramids and truncated pyramids) in bulk and thin GaN:Mg films grown with Ga polarity was determined at atomic resolution by direct reconstruction of the scattered electron wave in a transmission electron microscope. Small cavities were present inside the defects. The inside walls of the cavities were covered by GaN which grew with reverse polarity compared to the matrix. It was proposed that lateral overgrowth of the cavities restores matrix polarity on the defect base. Exchange of Ga and N sublattices within the defect compared to the matrix lead to a 0.6 {+-} 0.2 {angstrom} displacement between the Ga sublattices of these two areas. A [1{und 1}00]/3 shift with change from AB stacking in the matrix to BC within the entire pyramid is observe

6-{[(Benz­yloxy)carbon­yl]­oxy}-2-methyl­hexa­hydro­pyrano[3,2-d][1,3]dioxin-7,8-diyl bis­(chloro­acetate)

The asymmetric unit of the title compound, C20H22O10Cl2, consists of a 6-{[(benz­yloxy)carbon­yl]­oxy}group and two chloro­acetate groups bonded to a 2-methyl­hexa­hydro­pyrano[3,2-d][1,3]dioxin group at the carbon 1,2 and 3 positions, respectively, of a pyrano ring fused to a dioxin ring. The dihedral angle between the mean planes of the dioxin and benzyl rings is 42.2 (2)°. An extensive array of weak inter­molecular C—H⋯O hydrogen bonds links the mol­ecules into chains along [011]. Additional weak inter­molecular C—H⋯π inter­actions occur between C—H atoms of the dioxin and benzyl rings and a nearby benzene ring. A MOPAC geometry optimization calculation in vacuo revealed that the dihedral angle between the mean planes of the dioxin and benzyl rings increased by 24.42 to 66.64°, suggesting that the weak inter­molecular hydrogen-bonding inter­actions, in coord­ination with weak C—H⋯π inter­actions, influence the geometry of the resultant crystalline species and help to stabilize the crystal packing

Redetermination of 4-hydroxy­benzaldehyde

This is a redetermination of the structure of the title compound, C7H6O2, which was first reported by Iwasaki [Acta Cryst. (1977 ▶), B33, 1646–1648]. The results are obtained with greater precision in the present study. Crystal packing is stabilized by inter­molecular O—H⋯O inter­actions between the hydroxyl and aldehyde groups which link the mol­ecules into chains in a zigzag pattern along the [110] plane of the unit cell

A second polymorph of β-arteether

The crystal structure of the title compound, C17H28O5, reported here is a polymorph of the structure first reported by El-Feraly, Al-Yahya, Orabi, McPhail & McPhail [J. Nat. Prod. (1992). 55, 878–883]. It is a derivative of the anti­malaria compound artemisinin and consists primarily of three substituted ring systems fused together. A cyclo­hexane ring (distorted chair conformation) fused to a tetra­hydro­pyran group (distorted chair) is adjacent to an oxacyclo­heptane unit containing an endo-peroxide bridge, giving the mol­ecule its particular three-dimensional arrangement. The crystal packing is stabilized by inter­molecular C—H⋯O inter­actions between an O atom from the endo-peroxide bridge and H atoms from both the cyclo­hexane and seven-membered oxacyclo­heptane fused rings, as well as between an O atom and H atom from adjacent tetra­hydro­pyran rings. The two polymorphs have the same space group and similar cell parameters for the a and b axes, but significantly different values for the c axis

Exercise capacity and cardiac hemodynamic response in female ApoE/LDLR^{-/-} mice : a paradox of preserved V'O_{2max} and exercise capacity despite coronary atherosclerosis

We assessed exercise performance, coronary blood flow and cardiac reserve of female ApoE/LDLR-/- mice with advanced atherosclerosis compared with age-matched, wild-type C57BL6/J mice. Exercise capacity was assessed as whole body maximal oxygen consumption (V'O2max), maximum running velocity (vmax) and maximum distance (DISTmax) during treadmill exercise. Cardiac systolic and diastolic function in basal conditions and in response to dobutamine (mimicking exercise-induced cardiac stress) were assessed by Magnetic Resonance Imaging (MRI) in vivo. Function of coronary circulation was assessed in isolated perfused hearts. In female ApoE/LDLR-/- mice V'O2max, vmax and DISTmax were not impaired as compared with C57BL6/J mice. Cardiac function at rest and systolic and diastolic cardiac reserve were also preserved in female ApoE/LDLR-/- mice as evidenced by preserved fractional area change and similar fall in systolic and end diastolic area after dobutamine. Moreover, endothelium-dependent responses of coronary circulation induced by bradykinin (Bk) and acetylcholine (ACh) were preserved, while endothelium-independent responses induced by NO-donors were augmented in female ApoE/LDLR-/- mice. Basal COX-2-dependent production of 6-keto-PGF1α was increased. Concluding, we suggest that robust compensatory mechanisms in coronary circulation involving PGI2- and NO-pathways may efficiently counterbalance coronary atherosclerosis-induced impairment in V'O2max and exercise capacity

A systematic review of the safety of lisdexamfetamine dimesylate

BACKGROUND: Here we review the safety and tolerability profile of lisdexamfetamine dimesylate (LDX), the first long-acting prodrug stimulant for the treatment of attention-deficit/hyperactivity disorder (ADHD). METHODS: A PubMed search was conducted for English-language articles published up to 16 September 2013 using the following search terms: (lisdexamfetamine OR lisdexamphetamine OR SPD489 OR Vyvanse OR Venvanse OR NRP104 NOT review [publication type]). RESULTS: In short-term, parallel-group, placebo-controlled, phase III trials, treatment-emergent adverse events (TEAEs) in children, adolescents, and adults receiving LDX were typical for those reported for stimulants in general. Decreased appetite was reported by 25-39 % of patients and insomnia by 11-19 %. The most frequently reported TEAEs in long-term studies were similar to those reported in the short-term trials. Most TEAEs were mild or moderate in severity. Literature relating to four specific safety concerns associated with stimulant medications was evaluated in detail in patients receiving LDX. Gains in weight, height, and body mass index were smaller in children and adolescents receiving LDX than in placebo controls or untreated norms. Insomnia was a frequently reported TEAE in patients with ADHD of all ages receiving LDX, although the available data indicated no overall worsening of sleep quality in adults. Post-marketing survey data suggest that the rate of non-medical use of LDX was lower than that for short-acting stimulants and lower than or equivalent to long-acting stimulant formulations. Small mean increases were seen in blood pressure and pulse rate in patients receiving LDX. CONCLUSIONS: The safety and tolerability profile of LDX in individuals with ADHD is similar to that of other stimulants

(6Z)-3-Di­ethyl­amino-6-(3-hy­droxy­anil­ino­methyl­ene)cyclo­hexa-2,4-dien-1-one

In the title mol­ecule, C17H20N2O2, the angle between the mean planes of the 3-hydroxy­phenyl and cyclo­hexa-2,4-dien-1-one rings is 10.7 (7)°. Intra­molecular N—H⋯O hydrogen bonding involving the amine H atom and the carbonyl O atom affects the conformation of the mol­ecule. One of the ethyl arms is disordered over two conformations with occupancies of 0.766 (8) and 0.234 (8). Crystal packing is stabilized by inter­molecular C—H⋯O hydrogen bonding between the major component of the disordered ethyl C atom and a nearby carbonyl O atom, and by O—H⋯O hydrogen bonding between the hydroxyl H atom and the carbonyl O atom. This links the molecules into chains in an alternate inverted pattern, parallel, oblique and diagonal to the bc face of the unit cell

5-(Di­ethyl­amino)-2-[(Z)-(1-naphthyl­imino)meth­yl]phenol

In the title mol­ecule, C21H22N2O, the angle between the mean planes of the 1-naphthyl­imino and 2-methyl­yphenyl groups is 63.3 (2)°. The two diethyl extensions from the 5-diethyl­amino group are twisted in a + and − anti­periplanar conformation. One of the ethyl arms is disordered over two conformations with occupancies of 0.644 (3) and 0.356 (3). The crystal packing is stabilized by inter­molecular C—H⋯π inter­actions between π orbitals of the 1-naphthyl (I/II) rings and H atoms from a nearby benzene ring as well as from an ethyl C atom of an ethyl­amino group. The mol­ecules are stacked along the b axis in alternate inverted chains with the 1-naphthyl rings obliquely parallel to the ab face of the unit cell. Intra­molecular inter­actions between the hydroxyl H atom and the imino N atom provide additional conformational stability