Characterization of submicron particles during biomass burning and coal combustion periods in Beijing, China.

An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed along with other observation instruments to measure the characteristics of PM1 (particulate matter with a vacuum aerodynamic diameter of ≤1µm) during the biomass burning period (October 1 to 27; BBP) and the coal combustion period (December 10 to 31; CCP) in Beijing in 2014. The average PM1 mass concentrations during the BBP and CCP were 82.3 and 37.5µgm(-3), respectively. Nitrate, ammonium and other pollutants emitted by the burning processes, especially coal combustion, increased significantly in association with increased pollution levels. Positive matrix factorization (PMF) was applied to a unified high-resolution mass spectra database of organic species with NO(+) and NO2(+) ions to discover the relationships between organic and inorganic species. One inorganic factor was identified in both periods, and another five and four distinct organic factors were identified in the BBP and CCP, respectively. Secondary organic aerosols (SOAs) accounted for 55% of the total organic aerosols (OAs) during the BBP, which is higher than the proportion during the CCP (oxygenated OA, 40%). The organic nitrate and inorganic nitrate were first successfully separated through the PMF analysis based on the HR-ToF-AMS observations in Beijing, and organic nitrate components accounted for 21% and 18% of the total nitrate mass during the BBP and CCP, respectively. Although the PM1 mass concentration during the CCP was much lower than in the BBP, the average concentration of polycyclic aromatic hydrocarbons (PAHs) during the CCP (107.3±171.6ngm(-3)) was ~5 times higher than that in the BBP (21.9±21.7ngm(-3)).

Isolation and characterization of multipotent stem cells from human cruciate ligaments.

OBJECTIVES: Mesenchymal stem cells have great potential for tissue regeneration, and these cells can be harvested from a variety of tissues; however, up to now it has not been clear whether stem cells could be isolated from cruciate ligaments of the knee joint. The aim of our study was to isolate and characterize stem cells from both anterior and posterior cruciate ligaments (ACL and PCL) of humans. MATERIALS AND METHODS: Cruciate ligaments were obtained from patients receiving total knee arthroplasty for advanced osteoarthritis and plastic-adherent cells were serially passaged. In vitro chondrogenic, osteogenic and adipogenic abilities of the cells were evaluated by reverse transcriptase-polymerase chain reaction and histological study. Karyotyping and surface immunophenotyping of the cells were performed. RESULTS: It was found that a population of ligament-derived cells could be expanded and subcultured extensively. These cells were able to differentiate into osteoblasts, chondrocytes and adipocytes under appropriate inductions. Their phenotypic characteristics were similar to those of bone marrow mesenchymal stem cells. Karyotyping was normal after serial passage. CONCLUSIONS: In summary, our study demonstrates that human multipotent stem cells can be isolated and expanded from human ACL and PCL, which are easily obtained from patients following total knee or cruciate ligament reconstructive surgery. Self-renewal and mesodermal differentiation potential of these cells make them a viable alternative source for use in regenerative medicine.

Rabi oscillation damped by exciton leakage and Auger capture in quantum dots.

The decoherence of Rabi oscillation (RO) caused by biexciton, population leakage to the wetting layer (WL), and Auger capture in semiconductor quantum dots is theoretically analyzed with multilevel optical Bloch equations. The corresponding effects on the quality factor of RO are also discussed. We have found that the biexciton effect is relatively trifling, as the pulse duration is longer than 5 ps. The population leakage to the WL leads to a decrease of the RO average even though the damping rate is similar to that observed in the experiment. Auger capture in quantum dots results in RO damping that is consistent with the experimental data, which implies that Auger capture is an important decoherence process in quantum dots.

Coherent control of a V-type three-level system in a single quantum dot.

In a semiconductor quantum dot, the IIx and IIy transitions to the polarization eigenstates, |x> and |y>, naturally form a three-level V-type system. Using low-temperature polarized photoluminescence spectroscopy, we have investigated the exciton dynamics arising under strong laser excitation. We also explicitly solved the density matrix equations for comparison with the experimental data. The polarization of the exciting field controls the coupling between the otherwise orthogonal states. In particular, when the system is initialized into \Y>, a polarization-tailored pulse can swap the population into |x>, and vice versa, effectively operating on the exciton spin.

Characteristics of aerosols collected in central Taiwan during an Asian dust event in spring 2000.

Aerosol samples for PM(2.5) and PM(2.5-10) were collected at four locations in central Taiwan from 26 to 31 March 2000, a period that experienced exceedingly high PM levels from 29 to 30 March due to the passage of an Asian dust storm. The samples were analyzed for mass, metallic elements, ions, and carbon. The purpose of this paper is to investigate the influence of the dust storm on the characteristics of local ambient particulate matter. The results indicate that the concentrations of the crustal elements Ca, Mg, Al, Fe and the sea salt species Na+ and Cl- in PM(2.5-10) during the dust episode exceed the mean concentrations in the non-dust period by factors of 3.1, 2.9, 2.6, 2.2, 2.3 and 2.1 respectively. Enrichment factors of Ca, Fe, and Mg in PM(2.5-10) during the dust event are close to unity, indicating that these elements are from soil. Reconstruction of aerosol compositions revealed that soil of coarse particulates elevated approximately 50% in the dust event. It is noted that during the dust event, the ratio of Mg/Al in PM(2.5-10) ranged from 0.21 to 0.25 while that of Ca/Al ranged from 0.6 to 0.9, levels more constant than those obtained in non-dust period.

Successful treatment of mesenteric vasculitis caused by Henoch-Schönlein purpura with methylprednisolone pulse therapy.

Although mesenteric vasculitis due to Henoch-Schönlein purpura (HSP) is relatively uncommon, it is the most life-threatening manifestation associated with high mortality. We describe a 15-year-old boy with HSP who had massive gastrointestinal bleeding and ileus but delayed onset of the purpuric rash. Abdominal ultrasonography revealed thickening of both small and large intestinal walls, and CT found prominent mesenteric vessels with comb sign and double wall of the bowel. These findings were consistent with mesenteric vasculitis and bowel ischaemia. The ischaemic intestine recovered after methylprednisolone pulse therapy and surgical intervention was avoided. Our report suggests that corticosteroid pulse therapy may help controlling HSP with massive gastrointestinal haemorrhage and ischaemic bowel due to widespread mesenteric vasculitis.

Hibiscus protocatechuic acid inhibits lipopolysaccharide-induced rat hepatic damage.

Hibiscus protocatechuic acid (PCA), a phenolic compound found in the dried flowers of Hibiscus sabdariffa L. (Malvaceae), was demonstrated to have an antioxidant effect in vitro and in vivo, and an antitumor property in our previous study. In the present study, we used lipopolysaccharide (LPS, an endotoxin) to induce rat liver inducible nitric oxide synthase (iNOS), and found that pretreatment with PCA decreased the liver iNOS and the serum total nitrite induced by LPS. Our investigation showed that pretreatment of rats with PCA (0.2 and 0.5 mmol/kg dosed by gavage) for 5 days significantly decreased the serum levels of the hepatic enzyme markers alanine- and aspartate aminotransferase (ALT, alanine aminotransferase; AST, aspartate aminotransferase) induced by the 6-h treatment with LPS (i.p.; 5 mg/kg). Histopathological evaluation of the rat livers revealed that PCA reduced the incidence of liver lesions induced by LPS, including neutrophil infiltration, congestion, and liver cell swelling induced by LPS in rats. We conclude that PCA, an antioxidant, presents an inhibitory potential on iNOS and hepatic damage induced by LPS.

Congenital generalized lipodystrophy in a 4-month-old infant.

Congenital generalized lipodystrophy (CGL, Berardinelli-Seip syndrome) is a rare autosomal recessive disorder with a clinical presentation of paucity of adipose tissue, muscular hypertrophy, organomegaly, and insulin-resistant diabetes. A 4-month-old Taiwanese female infant had hepatosplenomegaly and low body weight gain despite a voracious appetite. Hypermetabolism, hyperhidrosis, loss of subcutaneous fat, muscular hypertrophy, acanthosis nigricans, hypertrichosis, and marked hypertriglyceridemia were also noted. Liver histology revealed fatty change and portal-to-portal bridging fibrosis. Clinical features, serum biochemistry, and liver histology were compatible with the diagnosis of CGL. She was given a special diet characterized by calorie restriction and partial substitution of long-chain triglycerides with medium-chain triglycerides. The serum triglyceride concentration subsequently decreased. This present case suggests that extensive fatty infiltration and subsequent cirrhosis of the liver may be the earliest complication of CGL.

Choledochal cyst in infancy: a follow-up study.

From January 1980 to February 1997, 19 cases, 8 males and 11 females, of choledochal cyst were diagnosed before one year old. The majority of patients were diagnosed by ultrasonography before 6 months old (15/19; 79%), including two diagnosed prenatally. According to Todani's classification, type Ia was the most common (74%), followed by type Ic (26%). Fourteen patients underwent Roux-en-Y choledocho- or hepatico-jejunostomy and cyst excision, 3 patients underwent Kasai operation, and I patient underwent external biliary drainage only. The remaining one patient with Trisomy 18 anomaly refused operation. Four of the 10 patients in whom liver histologic examinations were performed, had liver cirrhosis. The follow-up period of these patients ranged from 6 months to 9 years, with a mean of 4.1 years. We divided these 19 cases into 2 groups, according to the presence or absence of biliary atresia. In the 7 infants with biliary atresia (37%), all presented with jaundice and alcoholic stool. Two patients died due to delayed presentation and surgery, both had liver cirrhosis. One patient is living with liver cirrhosis. Another patient was lost to follow-up, but frequent cholangitis was noted till 8 months old. The remaining 3 patients are living and well. In the 12 without biliary atresia, 9 patients are living and well. Two patients died, one due to Trisomy 18 anomaly and the other with delayed surgery and liver cirrhosis. One case was lost to follow-up. In summary: 1-) a possibility of the association of biliary atresia in infants with choledochal cyst should be carefully searched and considered as a unique group; 2) ultrasonography is a good diagnostic tool in choledochal cyst during prenatal or infancy period; 3) the mortality cases were characterized by prolonged bile stasis, biliary cirrhosis, delayed surgery, or multiple anomalies; 4) surgery should be performed as early as possible for those with persistent jaundice and light colored stools.