Solidification of silicon for electronic and solar applications

Silicon is widely used for its semiconducting properties in electronic and photovoltaic devices. These applications require strict control of the structure and impurity levels. Silicon must, therefore, be solidified using processes that give a minimum of impurity contamination and microstructural defects, as well as a planar solidification front to avoid microsegregation. Czochralski growth, and to some extent float zone crystallization, are processes used to obtain defect-free single crystals for integrated circuits and advanced solar cell wafers, whereas the Bridgman process can be used for production of multicrystalline silicon for standard solar cells. Direct solar cell wafer solidification processes have also been developed and reached limited commercial use. The paper will review these silicon crystallization processes and discuss recent developments and trends.     

Investigations on the 4-quinolone-3-carboxylic acid motif part 5: modulation of the physicochemical profile of a set of potent and selective cannabinoid-2 receptor ligands through a bioisosteric approach

Three heterocyclic systems were selected as potential bioisosteres of the amide linker for a series of 1,6-disubstituted-4-quinolone-3-carboxamides, which are potent and selective CB2 ligands that exhibit poor water solubility, with the aim of improving their physicochemical profile and also of clarifying properties of importance for amide bond mimicry. Among the newly synthesized compounds, a 1,2,3-triazole derivative (1-(adamantan-1-yl)-4-[6-(furan-2-yl)-1,4-dihydro-4-oxo-1-pentylquinolin-3-yl]-1H-1,2,3-triazole) emerged as the most promising in terms of both physicochemical and pharmacodynamic properties. When assayed in vitro, this derivative exhibited inverse agonist activity, whereas, in the formalin test in mice, it produced analgesic effects antagonized by a well-established inverse agonist. Metabolic studies allowed the identification of a side chain hydroxylated derivative as its only metabolite, which, in its racemic form, still showed appreciable CB2 selectivity, but was 150-fold less potent than the parent compound.     

Inverting fractional order transfer functions through Laguerre approximation

This paper concerns the approximate inversion of fractional order transfer functions. The approximating solution is of the form of a weighted sum of Laguerre functions. The weights of the sum are found from a simple generating expression. As case study, the inversion of the Laplace transform of the Abel's equation is considered.     

Renal hydatidosis. Discussion of a clinical case complicated by post acute pancreatitic cyst

In this paper the authors describes a rare case of renal hydatidosis complicated by post acute pancreatitic cyst. There have been no reports up till now either of any physiopathological between the development of hydatid cysts in the vicinity of the pancreas and subsequent pancreatitis, or of any correlation between long-term albendazole therapy and acute pancreatitis. In our particular case, however, the volumetric increase of the renal cyst caused external compression of the pancreas and the consequent slowing-down of bilio-pancreatic flow, which probably led to the development of acute pancreatitis. Since, in our opinion, the pancreatic pseudocyst required surgical removal, we decided to perform the operation there and then; intraoperative examination of the cystic fluid and the presence of daughter cysts confirmed the suspected diagnosis of hydatidosis, of clear renal origin since it was closely attached to the upper pole and continued along the upper calyces renales; the cyst was easily detached from the lower and posterior edge of the liver, and was completely removed, together with its pericystium, which was detached from the lower surface of the liver and from the inferior subhepatic vein; only a tiny disk of pericystium was left in communication with a calyx, sutured to the rest of the kidney. The pancreatic cyst was drained by means of a mesocolic Roux-loop cysto-jejunostomy.     

Oligonucleotides‐decorated‐poly(N‐vinyl pyrrolidone) nanogels for gene delivery

Pulsed electron‐beam irradiation of a semi‐dilute poly(N‐vinyl pyrrolidone) (PVP) aqueous solution in the presence of acrylic acid has led to a carboxyl functionalized nanogel system. Nanoparticles hydrodynamic size and surface charge density, in water and as a function of pH, were investigated by dynamic light scattering and laser doppler velocimetry, respectively. Nanogels (NGs) were proved not to be cytotoxic at the cellular level. Indeed, they rapidly bypass the cellular membrane to accumulate in specific cell portions of the cytoplasm, in the perinuclear area. The availability of pendant carboxyl groups on the crosslinked PVP NGs core prompted us to attempt their decoration with a single strand oligonucleotide, which holds a terminal amino group. The recognition ability of the attached single helix of its complementary strand was investigated. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39774.     

Heat and light thematised in the modern architecture of Houston

Mid-twentieth-century modern architecture in Houston thematised responsiveness to the natural phenomena of heat and light despite the fact that Houston's most celebrated modern buildings were designed to be completely reliant on central air-conditioning. An examination of Houston buildings constructed from the late 1940s through the 1960s demonstrates the ways in which modern architects sought to privilege the architectural recognition of regional climatic difference while also employing modern technology to alleviate local climatic extremes of heat and humidity. The spectacular modern buildings that represent this era in Houston raise crucial questions: How did architects reconcile the doctrine of climatic responsiveness to the equally modern desire for maximum transparency? What proved more compelling: responsiveness to local circumstance or the imperatives of modern structural and mechanical engineering? Did modern architects perceive that there might be contradictions between responsiveness to climate and other aspects of modern architectural identity, such as transparency? Because concern about the roles of building design and construction in the responsible use of natural resources is current at the turn of the twenty-first century, it is pertinent to examine the ways modern architects in a particular climatic setting negotiated the issue of climatic responsiveness as modern architecture became the dominant practice.     

Effects of imipramine on raphe nuclei and prefrontal cortex extracellular serotonin levels in the rat

In healthy boys, the pituitary-gonadal axis exhibits diurnal variation in early puberty. Serum testosterone levels are higher during the night and low or immeasurable during the day. These fluctuating levels of circulating androgens in early pubertal boys are difficult to monitor. Prostate specific antigen (PSA) is a marker of the androgen-dependent prostatic epithelial cell activity and it is used in the diagnosis and surveillance of adult patients with prostatic cancer. We have measured PSA concentrations in serum from boys with precocious puberty before and during gonadal suppression with GnRH agonists to evaluate the effect of normal and precocious puberty on PSA levels and to study the correlation between testosterone and PSA in boys. METHODS: PSA was measured by an ultrasensitive immunofluorometric assay with a detection limit of 0.03 microgram/l. Testosterone was measured by an RIA with a sensitivity of 0.23 nmol/l, and sex hormone binding globulin was measured by a time-resolved immunofluorescence assay (sensitivity 0.23 nmol/l). Five boys with central precocious puberty (CPP) were studied before and after 12 months of GnRH agonist treatment. Sixty healthy boys (12 in each Tanner stage of puberty) and 37 healthy young males served as controls. RESULTS: PSA levels were immeasurable in all prepubertal boys, whereas PSA levels increased with increasing stage of pubertal maturation. There was a significant correlation between PSA and testosterone and free androgen indices (r = 0.61 and r = 0.65 respectively, both P < 0.001). All 5 boys with CPP had significantly elevated PSA levels which decreased to very low or immeasurable levels after GnRH agonist treatment. CONCLUSION: PSA may be a useful marker of testosterone activity in boys with normal or precocious puberty.     

A new route for the preparation of flexible skin–core poly(ethylene-co-acrylic acid)/polyaniline functional hybrids

Surface modification of polymeric films is a way to obtain final products with high performance for many specific and ad hoc tailored applications, e.g. in functional packaging, tissue engineering or (bio)sensing. The present work reports, for the first time, on the design and development of surface modified ethylene–acrylic acid copolymer (EAA) films with polyaniline (PANI), with the aim of inducing electrical conductivity and potentially enable the electronic control of a range of physical and chemical properties of the film surface, via a new “grafting from” approach. In particular, we demonstrate that PANI was successfully polymerized and covalently grafted onto flexible EAA substrates, previously activated. The final hybrid materials and the corresponding intermediates were fully characterized via FTIR, XPS, SEM–EDAX, mechanical and electrical tests. The mechanical properties of the films are not detrimentally affected by each treatment step, while a significant increase in electrical conductivity was achieved for the new hybrid materials.     

Improved heat stability by whey protein–surfactant interaction

One of the main changes that occur during heat treatment of milk is whey protein denaturation, which in its turn may lead to protein aggregation and gelation. In this contribution, the effect of lysophospholipids, the main components of lysolecithins, as well as alternative surfactants, on heat-induced whey protein aggregation has been studied. Hereby, attention was paid to the relation between polar lipid molecular structure (e.g. effect of alkyl chain length, effect of polar head group) and heat-stabilising properties. Residual protein determination in the supernatant obtained after centrifugation of heated whey protein solutions learned that whey protein aggregation was at least partly prevented in the presence of surfactants. As the short alkyl chain lysophospholipids were particularly effective heat stabilisers, hydrophilic surfactants seemed to be most effective, which may be ascribed to their higher critical aggregation concentration. Upon more severe heat treatment, protein aggregation was probed either in-situ by oscillatory rheology, or ex-situ by yield rheometry. As some surfactants significantly reduced the gel strength, or even prevented heat-induced gel formation, these experiments corroborated the heat-stabilising effect of hydrophilic surfactants. Nuclear Magnetic Resonance (NMR) enabled a more direct evaluation of the protein–surfactant interaction. A strong hydrophobic interaction between small molecular weight surfactants and whey proteins became obvious from the chemical shift of the surfactant hydrophobic groups in the NMR spectrum and could be quantified by pulsed field gradient NMR (pfg-NMR) diffusiometry. The results indicated that protein–surfactant interaction did not occur upon thermal denaturation, but already took place at room temperature. However, the effect of this interaction became mainly obvious during thermal treatment.