GeSn lateral p-i-n waveguide photodetectors for mid-infrared integrated photonics.

In this Letter, we demonstrate mid-infrared (MIR) lateral p-i-n GeSn waveguide photodetectors (WGPDs) on silicon, to the best of our knowledge for the first time, as a key enabler of MIR electronic-photonic integrated circuits (EPICs). Narrow-bandgap GeSn alloys were employed as the active material to enable efficient photodetection in the MIR region. A lateral p-i-n homojunction diode was designed and fabricated to significantly enhance the optical confinement factor of the guided modes and thus enhance the optical responsivity. Thus, a photodetection range of up to 1950 nm and a good responsivity of 0.292 A/W at 1800 nm were achieved. These results demonstrate the feasibility of planar GeSn WGPDs for monolithic MIR EPICs on silicon.

Ge-on-insulator lateral p-i-n waveguide photodetectors for optical communication.

We report high-performance lateral p-i-n Ge waveguide photodetectors (WGPDs) on a Ge-on-insulator (GOI) platform that could be integrated with electronic-photonic integrated circuits (EPICs) for communication applications. The high-quality Ge layer affords a low absolute dark current. A tensile strain of 0.144% in the Ge active layers narrows the direct bandgap to enable efficient photodetection over the entire range of C- and L-bands. The low-index insulator layer enhances optical confinement, resulting in a good optical responsivity. These results demonstrate the feasibility of planar Ge WGPDs for monolithic GOI-based EPICs.

Concurrent dual-scopic management of diaphragm disease.

With the increasing appliance of minimally invasive approaches in both thoracic and general surgery, more and more diaphragmatic conditions are being managed with laparoscopy or thoracoscopy. Which one is adopted depends on the disease, facility support and surgeon's preference. However, in difficult scenarios such as adhesions, uncertain tumour location or bulky herniated organs, addition of another approach could be beneficial. Here we describe 2 cases, one with metastatic tumours within the diaphragm and another with diaphragmatic hernia in which concurrent thoracoscopic and laparoscopic, so-called dual-scopic, management was performed.

Determination of alkylphenol residues in baby-food purees by steam distillation extraction and gas chromatography-mass spectrometry.

This paper describes a simple and sensitive method for determining alkylphenols namely 4-tert-octylphenol (4-t-OP) and the isomers of 4-nonylphenol (4-NPs) present in various types of baby-food purees. The method involves extracting a sample with n-hexane for 1h using a modified Nielson-Kryger steam distillation extraction system and then identifying and quantitating the alkylphenols using a gas chromatography-mass spectrometry (GC-MS) operated in the selected ion monitoring (SIM) mode. The extraction conditions were evaluated at various values of pH of the sample solution. The limits of quantitation for this method were 0.2 ng/g from 1.0 g (wet weight) samples of 4-t-OP and the 4-NPs. The intra- and interbatch precisions and accuracies were also determined. The precision, in terms of the relative standard deviation (RSD), were less than 8%. Most of the recoveries of the alkylphenols from various spiked samples exceeded 60%, while the values of RSD ranged from 1% to 10%. Alkylphenol residues were detected in baby-food purees at concentrations of up to 19 ng/g (wet weight) for 4-t-OP and up to 21 ng/g (wet weight) for the 4-NPs.

Derivatization procedures and determination of levoglucosan and related monosaccharide anhydrides in atmospheric aerosols by gas chromatography-mass spectrometry.

This study evaluated the derivatization procedures for detecting the three most commonly monosaccharide anhydrides (MAs) (levoglucosan, mannosan and galactosan) in atmospheric aerosols using gas chromatography-mass spectrometry (GC-MS). Various silylating agents, mainly trimethylsilylating agents (TMS), were compared and the effects of various contents of trimethylchlorosilane (TMCS, as a stimulator) were evaluated to optimize the conditions for detecting these compounds in aerosol samples. Differences among the abundances of the derivatives were caused by the sterical hindrance of three hydroxyl groups in the structures of monosaccharide anhydrides. The effects of the reaction time and temperature were also examined. The optimal reaction time and temperature were 60min and 80 degrees C with 1% TMCS plus 0.2% 1,4-dithioerythritol (DTE). Under these conditions, the percentages of formation of bis-O-TMS derivatives (as by-products) were 23, 29 and 10% for galactosan, mannosan and levoglucosan, respectively. The concentrations of galactosan, mannosan and levoglucosan in particles of smoke samples ranged from 29 to 88, 23 to 69 and 77 to 380ng/m(3), respectively; and in particles of atmospheric aerosols ranged from 0.06 to 0.75, n.d. to 0.49 and 1.6 to 132ng/m(3), respectively. Levoglucosan was the dominant MAs detected in both type of samples. Less than 10% quantitation difference was obtained when bis-O-TMS derivatives were included in the calculation.

Occurrence and seasonal variation of alkylphenols in marine organisms from the coast of Taiwan.

The occurrence and distribution of alkylphenols (APs, i.e., 4-tert-octylphenol (4-t-OP) and 4-nonlyphenol isomers (4-NP)) in oysters (Crassostrea gigas), snails (Thais clavigera), coastal water and coastal sediments of the western coast of southern Taiwan are investigated. Alkylphenols were present in all matrices of interest: in water, ranging from 61 to 370 ng/l, in sediments, ranging from 27 to 190 ng/g, and in biota samples (i.e., oyster and snail), ranging from 20 to 5190 ng/g. Statistical analysis indicated that the probability distribution of most determined concentrations in oyster and snail samples was log-normal distribution. The bioaccumulation of APs resulted in a seasonal variation with respect to their compositions and concentrations in oyster and snail samples. For oysters, concentrations of APs in winter exceeded those in summer. In contrast, those in snails in summer exceeded those in winter. Estimated biomagnification factors of APs from snails to oysters ranged from 1.4 to 4.3 in summer, and 0.5 to 0.8 in winter on the dry weight basis. The results suggested that seasonally mediated physiological changes, such as dilution caused by growth, biotransformation and metabolism, may affect the bioaccumulation of APs in according to season and organism.

Determination and distribution characteristics of degradation products of nonylphenol polyethoxylates in the rivers of Taiwan.

Concentrations of degradation products of nonylphenol polyethoxylates (NPEOs) were analyzed in river water samples in order to determine the distribution characteristic of these alkylphenolic compounds in 18 major rivers of Taiwan. The degradation products of NPEOs were detected in all river samples, with the dicarboxylates alkylphenolic degradation products (CAPEC) being detected most frequently and at the highest concentrations. Concentrations of NP and NP1EO in rivers ranged from n.d. to 5.1 microg l(-1) and n.d. to 0.5 microg l(-1), respectively. The total concentrations of shortened carboxylates (i.e., NP1EC+NP2EC+NP3EC) and dicarboxylates alkylphenolic degradation products (CAP1EC+CAP2EC) ranged from n.d. to 63.6 microg l(-1) and n.d. to 94.6 microg l(-1), respectively. Concentrations of NP2EC, NP3EC and all CAPEC residues were determined semi-quantitatively by comparing with the internal standard. Significantly higher concentrations of CAPEC residues were detected in the river waters as compared to those of NP, NP1EO and NPEC degradation products and the average proportions of these compounds in the samples of the rivers were as follows: NP+NP1EO was 5+/-2.5%, total NPEC was 25+/-12%, and total CAPEC was 70+/-12%. The high concentration ratios of CAPEC/NPEC illustrate that aerobic biodegradation plays a main route in the fate of NPEO in the rivers of Taiwan.

Synthesis and determination of dicarboxylic degradation products of nonylphenol polyethoxylates by gas chromatography-mass spectrometry.

The synthesis and determination of persistent dicarboxylic metabolites of alkylphenol polyethoxylates (NPEOs), carboxyalkyl phenoxy ethoxy carboxylates (CAPECs), are investigated. The synthesized CAPECs have three and four carbon atoms and a carboxyl group in the alkyl chain side, and a carboxymethoxy acid group in its para-position (expressed as CA(3)P1EC and CA(4)P1EC in their abbreviation). The synthesis was successfully accomplished via a four-step reaction sequence that started from 4-fluoroanisole. After propylation by a propanol/acetyl chloride procedure, the derivatives of synthesized CA(3)P1EC and CA(4)P1EC were separated and identified by GC-MS with electron impact ionization (EI). The most abundant characteristic ions were produced by benzylic cleavages of carboxyalkyl chain to yield [M-87](+), corresponding to ions of m/z 235 for CA(3)P1EC and m/z 249 for CA(4)P1EC. Recoveries of synthesized CA(3)P1EC and CA(4)P1EC in various spiked water samples ranged from 82 to 92% with relative standard deviations (RSD) lesser than 7%. The limits of quantitation (LOQ) of CA(3)P1EC and CA(4)P1EC were estimated to be 0.005 and 0.01 microg/l in 100ml of water samples, respectively. The concentrations of CA(4)P1EC residues were detected in the aquatic environment ranging from n.d. to 3.24 microg/l. The results show that the synthesized CA(4)P1EC has been successfully applied to more accurately determine the concentrations of CA(4)P1EC residues in water samples.

Flexible endoscopy of aerodigestive tract in small infants.

BACKGROUND: Flexible endoscopy (FE) is a useful method for diagnosing airway problems. Congenital or acquired airway lesions in infants may lead to respiratory distress that requires comprehensive investigation and management. This study was designed to evaluate the use of FE in small infants. METHODS: Infants who had symptoms of respiratory distress and received FE when they were less than 1-year-old were studied and their medical history, diagnoses, interventions, and complications from FE were investigated. RESULTS: The study population consisted of 568 small infants (334 boys and 234 girls) who weighed 5.1 +/- 2.4 kg, and received FE when they were 4.5 +/- 3.6 months of age. Most patients (91.2%) received diagnostic FE and the remainder (8.8%) received therapeutic procedures. Stridor (38.0%) was the most common indication for FE and laryngomalacia (33.3%) was the most frequent finding. Synchronous FE diagnosis was found in 351 (61.8%) cases. No major complications associated with FE were found. CONCLUSION: Flexible endoscopy allows direct visualization of dynamic motion of the small aerodigestive tract. Laryngomalacia was the most common FE finding of respiratory distress in small infants. Synchronous FE lesions were frequently found in this young age group and it necessitated a thorough investigation of the entire aerodigestive tract.

Endotracheal tube position in pediatrics and neonates: comparison between flexible fiberoptic bronchoscopy and chest radiograph.

BACKGROUND: Correct tracheal intubation in critically ill patient is very important in intensive care medicine. The purpose of this study is to evaluate the value and accuracy of the flexible fiberoptic bronchoscopy (FFB) in confirming the endotracheal tube (ETT) position and to compare with the chest radiograph method in intubated pediatric and neonate patients. METHODS: We prospectively used the FFB to evaluate the ETT position in the pediatric and neonate intensive care units (ICUs) from January 2000 to December 2000. The distance between the ETT tip and the trachea carina measured by FFB (TC-FFB) was recorded and compared with that by the chest radiograph (TC-CR). The consuming time needed for checking the ETT position was also compared between these two methods. RESULTS: There were 74 cases enrolled. There was a significant correlation between TC-FFB and TC-CR (r = 0.898, p = 0.000). It took less time to confirm the ETT position by using the FFB than by the post-intubation chest radiograph (0.3 +/- 0.1 min vs. 103.8 +/- 45.2 min, p < 0.05). No major complication was noted in performing the FFB measurement. CONCLUSIONS: FFB is an accurate, convenient, timesaving and less traumatic technique in confirming the correct ETT position for the critical and emergent patients in the pediatric and neonate ICUs.

Determination of nonylphenol polyethoxylates in household detergents by high-performance liquid chromatography.

Preliminary survey results of the content of nonylphenol polyethoxylates (NPEOs) in various household detergents sold in Taiwan are presented. This survey was conducted to elucidate the concentration of NPEOs in household detergents and support pollution prevention and control programs. The concentrations of NPEOs in detergents and cleaners were determined by HPLC with a C8 reversed-phase column and equipped with fluorescence detection. The accuracy and precision of the method was validated and was successfully applied to determine concentrations of NPEOs in household detergents. The results show that NPEOs were detected in 41% of 90 household detergents at concentrations from 0.2 to 21%. The highest concentration of NPEOs (21%) was detected in a laundry liquid especially designed for washing socks. Reversed-phase liquid chromatography connected with electrospray mass spectrometry confirmed the results.

Nasopharyngeal tract length measurement in infants.

UNLABELLED: Artificial nasopharyngeal (NP) airway is a common device used to secure upper airway patency. The proper length of its insertion is important, especially in infants. The purpose of this study is to measure and compare the endoscopic and the anthropometric measurements of NP length in infants. MATERIAL AND METHODS: We collected data from 413 infants who received flexible fiberoptic endoscopy. Endoscopic measurement length is from the nostril to the vocal cord (N-V distance). Anthropometric measurement length is from the nose tip to the earlobe. We stratified the infants into four groups by body weight and compared the difference between the two measurement methods. RESULTS: The mean length of the endoscopic measurement is compatible to the anthropometric measurement in all four groups. There is a statistically significant correlation between the N-V distance and the body length (p = 0.0001, r = 0.83), the body weight (p = 0.0001, r = 0.81), and the age (p = 0.0001, r = 0.64). CONCLUSION: The anthropometric measurement of nasopharyngeal airway length is nearly identical to the endoscopic measurement.