[Near-infrared quantum cutting downconversion luminescence of Yb3+ ion cooperative energy transferred from YVO4 matrix donor].

The present manuscript researches the near infrared quantum cutting luminescence phenomena of Yb3+ ion in YVO4 crystal matrix The luminescence spectra, excitation spectra and fluorescence lifetimes were measured. It was found that the excitation of YVO4 crystal matrix energy band by 322.0 nm light can result in the effective secondary cooperative energy transfer of Yba+ ion from the YVO4 crystal matrix It results in the intense 985.5 nm 2F(5/2)-->2F(7/2) near infrared quantum cutting luminescence of Yb3+ ion. Meanwhile, the 430.O nm luminescence intensity of YVO4 crystal matrix decreases greatly. From the experimental measurements, it was found that the lifetime of 430.0 nm fluorescence of (A) Yb(1.5) : YVO4 crystal is tauA = 3.785 s and that of (B) YVO4 crystal is tauB=22.72 s. It was found also that the theoretical efficiency up limit of quantum cutting of (A) Yb(1.5) : YVO4 crystal is about eta1.5%=183-3%.

[Three photons quantum-cutting system on the rear surface of cells to improve the efficiencies of solar cells].

The authors present a solar cell model with a three photons quantum-cutting system on the rear surface, then the method of calculation of limiting efficiencies was used to get the maximum efficiency 58.58% at the band gap Eg=0.9315 eV, and in contrast with two-photons quantum-cutting system, it is greatly improved. The result can prove that the three-photons quantum-cutting has a great sense to improve the efficiencies of solar cells. It is the exciting development for us to find out the useful luminescence materials to get the high efficiency.

[The changing process of population probability and fluorescence intensity in ErP5O14 noncrystalline from 0 second to stabilization].

The results of numerical simulation were compared respectively with and without considering the improved coefficient for the energy transfer process in ErP5O14 noncrystalline under 521.8, 450.0, 405.5 and 378.5 nm lights excitation. The results showed that it is essential to take the coefficient into calculation where energy transfer plays a key role. The relative fluorescence intensity ratios of 4I13/2-->4I15/2 to 4I11/2-->4I15/2 under 523.8, 450.0 and 378.5 nm lights excitation were 2.11, 2.82 and 2.99 times larger than that under 979.3 nm light excitation respectively. There are obviously effective near-infrared (NIR) quantum cutting of 4I13/2-->4I15/2 transition. The result indicates that ErP5O14 noncrystalline has potential application in the enhancement of conversion efficiency of germanium solar cells.

[A norovirus-borne outbreak caused by contaminated bottled spring water in a school, Zhejiang province].

OBJECTIVE: To study a local hospital reported acute gastroenteritis in a boarding school on its source of infection, mode of transmission and risk factors of the infection. METHODS: A suspected case was defined as who had developed diarrhea (≥ 3 times/day) or vomiting among teachers or students of the school, during April 19 - 30, 2010. A confirmed case was from a probable case plus tested positive for norovirus in stool specimens by using RT-PCR. Stool specimens of cases and environmental specimens were collected for laboratory diagnosis. In a case-control study, we compared exposures to sources of bottled water, consumption of bottled water, and hygienic habits of 220 probable or confirmed cases from April 21 - 23 in the peak of the outbreak, together with another 220 controls, with frequency-matched by school grade. RESULTS: 20.3% of the 1536 students but none of the teachers developed the disease. 98.6% of the cases (n = 217) and 85.5% (n = 188) of the controls had drunk bottled water in the classroom (OR(M-H) = 12.3, 95%CI: 3.7 - 40.9). 47.9% (n = 104) of the cases and 41.5% (n = 78) of the controls had drunk unboiled bottled water in classroom (OR(M-H) = 3.8, 95%CI: 1.5 - 9.6). 47.9% (n = 104) of the cases and 48.4% (n = 91) of the controls had drunk bottled mixed water (boiled and unboiled) in the classroom (OR(M-H) = 2.8, 95%CI: 1.1 - 7.0). Stool specimens from 3 cases and one bottle of uncovered bottled water in classroom showed positive of having norovirus genotype II. Coliforms was cultured much higher rates than standard deviations in the bottled water. The factory making the bottled water was not licensed or having strict disinfection facilities. CONCLUSION: Bottled spring water contaminated by norovirus was responsible for this outbreak.

[Molecular characteristics of noroviruses causing outbreaks of acute gastroenteritis in Huzhou].

OBJECTIVE: To study the molecular characteristics of Noroviruses causing outbreaks of acute gastroenteritis in Huzhou. METHODS: From 2008 to 2010, total 119 fecal specimens collected from outbreaks of acute gastroenteritis were tested for Norovirus. Partial sequence of RNA dependent RNA polymerase (RdRp) of the positive samples were amplified by RT-PCR, then the PCR production were purified, sequenced and put into phylogenetic analysis. RESULTS: 50 of 119 specimens were positive for Norovirus by real-time RT-PCR. Out of those 50 Norovirus positive specimens, 9 were Norovirus Genogroup I (GI) positive, 35 were Norovirus Genogroup II (GII) positive, 6 was both Norovirus GI and GII positive. 12 PCR products for RdRp were selected for further studies on sequencing. Phylogenetic analysis revealed that the 5 GI norovirus isolates were belonged to genotype GI/2 and GI/3. Of the 7 GII norovirus isolates, 6 were belonged to genotype GII/4, 1 was belonged to genotype Glib. CONCLUSION: Norovirus is a major cause of outbreaks of acute gastroenteritis in Huzhou and the epidemic strains of norovirus isolated from Huzhou had a high degree of genetic diversity.

[Epidemiological study and clinical analysis of 113 laboratory-confirmed cases with hand, foot and mouth disease].

OBJECTIVE: To analyse the epidemiological and clinical characteristics of different pathogenesis type cases, severe and common cases of hand, foot and mouth disease. METHODS: Descriptive epidemic method was used to analyse the epidemiological and clinical characteristics of laboratory-confirmed cases with hand,foot and mouth disease. RESULTS: The epidemiological characteristics 113 cases were the same as epidemic situation at the same time in Anji county. Clinical characteristics were difference in different pathogenesis type cases, severe and common cases of hand, foot and mouth disease. CONCLUSION: Prevention and control work taken should according to the characteristics of the disease, such as early identification of severe cases, handling and controlling over the outbreaks in order to reduce the severe cases and the death.

[An investigation and analysis on an outbreak of acute gastroenteritis caused by genogroup I and II norovirus].

OBJECTIVE: To investigate the cause of an outbreak characterized by diarrhea and vomit in a middle school in Huzhou City. METHODS: Comprehensive analysis was conducted based on field epidemiological study, clinical characteristics of the cases and laboratory test. RESULTS: 578 cases of acute gastroenteritis were found. The attack rate was 23.58%. The most frequently observed clinical symptoms were diarrhea, vomiting, abdominal pain and nausea. Some few had fever. Most cases had slight clinical symptom with a course from 1 to 3 days. The cases were distributed in every class, showing no phenomenon of clustering. Norovirus were detected in 11 out of 15 stool samples by using RT-PCR. 6 were genogroup II norovirus. 3 were genogroup I norovirus. enogroup I and II norovirus were detected at the same time in 2 stool samples (the same student with 2 tests). Case-control study showed that drinking unheated bottled water was risk factor (OR = 2.46, 95% CI = 1.19-5.23), and had a dose response relation with the disease (chi = 24.8 P < 0.01). The epidemic was controlled soon through isolating patients during treatment, providing boiled water, disinfecting and health education. CONCLUSION: This was an infectious diarrhea outbreak caused by norovirus. The suspected transmission ways were drinking unheated bottled water and contact daily.