Continuous time-varying biasing approach for spectrally tunable infrared detectors

In a recently demonstrated algorithmic spectral-tuning technique by Jang et al. [Opt. Express 19, 19454-19472, (2011)], the reconstruction of an object’s emissivity at an arbitrarily specified spectral window of interest in the long-wave infrared region was achieved. The technique relied upon forming a weighted superposition of a series of photocurrents from a quantum dots-in-a-well (DWELL) photodetector operated at discrete static biases that were applied serially. Here, the technique is generalized such that a continuously varying biasing voltage is employed over an extended acquisition time, in place using a series of fixed biases over each sub-acquisition time, which totally eliminates the need for the post-processing step comprising the weighted superposition of the discrete photocurrents. To enable this capability, an algorithm is developed for designing the time-varying bias for an arbitrary spectral-sensing window of interest. Since continuous-time biasing can be implemented within the readout circuit of a focal-plane array, this generalization would pave the way for the implementation of the algorithmic spectral tuning in focal-plane arrays within in each frame time without the need for on-sensor multiplications and additions. The technique is validated by means of simulations in the context of spectrometry and object classification while using experimental data for the DWELL under realistic signal-to-noise ratios

Breaking the Buildup-time Limit of sensitivity in Avalanche Photodiodes by Dynamic Biasing

Avalanche photodiodes (APDs) are the preferred photodetectors for direct-detection, high data-rate long-haul optical telecommunications. APDs can detect low-level optical signals due to their internal amplification of the photon-generated electrical current, which is attributable to the avalanche of electron and hole impact ionizations. Despite recent advances in APDs aimed at reducing the average avalanche-buildup time, which causes intersymbol interference and compromises receiver sensitivity at high data rates, operable speeds of commercially available APDs have been limited to 10Gbps. We report the first demonstration of a dynamically biased APD that breaks the traditional sensitivity-versus-speed limit by employing a data-synchronous sinusoidal reverse-bias that drastically suppresses the average avalanche-buildup time. Compared with traditional DC biasing, the sensitivity of germanium APDs at 3Gbps is improved by 4.3 dB, which is equivalent to a 3,500-fold reduction in the bit-error rate. The method is APD-type agnostic and it promises to enable operation at rates of 25Gbps and beyond

Characteristics of dibenzothiophene desulfurization by Rhodococcus erythropolis R1 and its Dsz-negative mutant

Introduction: Biodesulfurization is used as a selective method for lowering the sulfur content of petroleum products. Materials and methods: A sulfur-oxidation bacterial strain named Rhodococcus erythropolis R1 (NCBI GenBank Accession No. GU570564) was used in this study for desulfurization of dibenzothiophene (DBT). Results: The induced culture of strain R1 was able to produce 2-hydroxybiphenyl (2- HBP) from DBT followed 4S pathway without further degrading carbon backbone. This process confirmed by gas chromatography (GC) analysis. The specific activity of DBT desulfurization by R1 was 45 µM (g dry wt)-1 h-1. The addition of Tween 80 as surfactant and glycerol as carbon source determines a 100% rate of DBT-desulfurization during 3 days. The heavy plasmid detected in R1 strain carries dsz genes responsible for biodesulfurization of DBT that was shown by PCR reaction. The mutant strains which had lost this plasmid also had lost desulfurization phenotype. Both mutant and wild strain were sensitive to high concentration of 2-HBP and some antibiotics. Discussion and conclusion: Strain R1 desulfurize DBT through the sulfur-specific degradation pathway or 4S pathway with the selective cleavage of carbon-sulfur (C-S) bonds without reducing the energy content. Addition of surfactant enhanced the desulfurization of DBT by increasing its bioavailability and also could improve the growth and desulfurization rate. The location of desulfurization genes was on a heavy plasmid in strain R1. Based on the results of this study, R. erythropolis R1 could serve as a model system for efficient biodesulfurization of petroleum oil without reducing the energy value

Thyroid Hormone Levels in Preterm Neonates with Birth Weight Less than 2500 g, Treated with Phenobarbital

ObjectivesIndicatively, phenobarbital can impair thyroid function in adults and children. The present research aims to evaluate the thyroid hormone levels in preterm neonates who had received phenobarbital treatment.Materials & MethodsThis study was conducted on preterm neonates who weighed less or equal to 2500 g when phenobarbital was prescribed for treatment in the first 15 days of life. TSH and total T4 measurements were performed before and three months after initiation of phenobarbital.ResultsIn this study, the sum of preterm neonates stood at 94, of which 53 were girls, with a mean birth weight of 2004.41 ± 315.41g. Weight of 8.5% were under 1500 g. The mean gestational agewas estimated at 33.64 ± 2.01 weeks. Mean T4 levels were 12.24 ± 1.96 and 12.07 ± 1.95 (p=0.334), and mean TSH levels were 5.34 ± 2.14 and5.15 ± 2.15 (p=0.376) before and after prescribingphenobarbital, respectively. The same results were compared based on sex, gestational age, birth weight, and height for T4 and TSH and T4 based on head circumference. The only significant difference was TSH in preterm infants with head circumference <32 cm before and after prescribing phenobarbital (p=0.030). ConclusionIn preterm newborns that had less than 2500 g birth weight, phenobarbital did not significantly alter the serum thyroid hormone level

Effect of Plant Oils upon Lipase and Citric Acid Production in Yarrowia lipolytica Yeast

The nonconventional yeast Yarrowia lipolytica degrades very efficiently hydrophobic substrates to produce organic acids, single-cell oil, lipases, and so forth. The aim of this study was to investigate the biochemical behavior and simultaneous production of valuable metabolites such as lipase, citric acid (CA), and single-cell protein (SCP) by Yarrowia lipolytica DSM 3286 grown on various plant oils as sole carbon source. Among tested plant oils, olive oil proved to be the best medium for lipase and CA production. The Y. lipolytica DSM 3286 produced 34.6 ± 0.1 U/mL of lipase and also CA and SCP as by-product on olive oil medium supplemented with yeast extract. Urea, as organic nitrogen, was the best nitrogen source for CA production. The results of this study suggest that the two biotechnologically valuable products, lipase and CA, could be produced simultaneously by this strain using renewable low-cost substrates such as plant oils in one procedure

Fluid Replacement Therapy in Different Medical Conditions in Children

Vascular access and Intravenous Fluid (IVF) administration are essential issues in childrenwho are admitted to the emergency wards. Despite the common use of maintenance IVF,there are a lot of variations in fluid administration methods and no definite guidelines for IVFand electrolyte monitoring. Because hypotonic fluids cause hyponatremia in many children,isotonic fluids are indicated, according to recent studies, as an accepted method in pediatricIVF therapy to prevent hyponatremia. This narrative review aims to provide an evidencebasedapproach for selecting the most appropriate IVFs in patients aged 1 day to 18 years.Data showed that the basis of fluid therapy in children varies according to the type of diseaseand the underlying conditions of children. Depending on each case, the clinicians shoulddecide on what and how fluid and electrolytes be used

Biased Treg/Th17 balance away from regulatory toward inflammatory phenotype in relapsed multiple sclerosis and its correlation with severity of symptoms

The opposing immune functions of Treg and Th17 lymphocytes and the plasticity of Treg/Th17 differentiation, has led us to investigate the effects of their fluctuations and counterbalance in autoimmune condition of multiple sclerosis (MS). Evaluation of Treg and Th17 frequency in peripheral blood of a group of relapsed MS patients, showed a decrease in Treg/Th17 ratio compared to that of healthy controls. A reverse correlation between these subsets was observed in controls but not in patient groups. Both Treg frequency and Treg/Th17 ratio were negatively correlated with severity of symptoms. There was shown to be an enduring increase in Treg frequency associated with MS disease

Leptin promotes melanoma tumor growth in mice related to increasing circulating endothelial progenitor cells numbers and plasma NO production

<p>Abstract</p> <p>Background</p> <p>Epidemiological studies propose that obesity increases the risk of several cancers, including melanoma. Obesity increases the expression of leptin, a multifunctional peptide produced predominantly by adipocytes which may promote tumor growth. Several recently experiments have suggested that the tumors growth is in need of endothelial progenitor cell (EPC) dependent generation of new blood vessels.</p> <p>Our objectives in the present study were to examine the effects of leptin on melanoma growth, circulating EPCs number and plasma levels of nitric oxide metabolites (NOx).</p> <p>Methods</p> <p>2 × 10⁶B16F10 melanoma cells were injected to thirty two C57BL6 mice subcutaneously. The mice were randomly divided into 4 groups (n = 8) in 8th day. Two groups were received twice daily intraperitoneal(i.p) injections of either PBS or recombinant murine leptin (1 μg/g initial body weight). Two groups were received i.p. injections of either 9F8 an anti leptin receptor antibody or the control mouse IgG at 50 μg/mouse every 3 consecutive days. By the end of the second week the animals were euthanized and blood samples and tumors were analyzed.</p> <p>Results</p> <p>The tumor weight, EPC numbers and NOx level in leptin, PBS, 9F8, and IgG group were (3.2 ± 0.6, 1.7 ± 0.3, 1.61 ± 0.2,1.7 ± 0.3 g), (222.66 ± 36.5, 133.33 ± 171, 23.33 ± 18, 132.66 ± 27.26/ml of blood), and (22.47 ± 5.5, 12.30 ± 1.5, 6.26 ± 0.84, 15.75 ± 6.3 μmol/L) respectively. Tumors weight and size, circulating EPC numbers and plasma levels of NOx were significantly more in the leptin than 9f8 and both control groups (p < 0.05). The plasma concentration of NOx significantly decreased in 9f8 treated mice compare to control group (p < 0.05).</p> <p>Conclusions</p> <p>In conclusion, our observations indicate that leptin causes melanoma growth likely through increased NO production and circulating EPC numbers and consequently vasculogenesis.</p