Background Pertussis is a reported vaccine-preventable respiratory disease in China. Because the routine laboratory methods for diagnosis are not in use, the reported cases are mainly in infants with classical paroxysmal cough and the true incidence related to pertussis is most likely under estimated. In China, however, few studies have attempted to address this issue. The purpose of this cross sectional study was to estimate the incidence rates using the method of sero-epidemiology of immunoglobulin (Ig) G antibodies against pertussis toxin (PT) among healthy populations in China. Methods Blood samples were obtained from 1313 healthy individuals aged 0 to 95 years in Guangdong province of China throughout September 2010. Serum IgG antibodies against PT were determined by commercial ELISA kits. Subjects with concentration of anti-PT IgG higher than 30 IU/mL were indicated to have recent Bordetella pertussis infection, if they have not received a booster dose of pertussis vaccine within one year. Results Of the 1313 study subjects, 117 (8.91%) were found to have anti-PT antibodies higher than 30 IU/mL. The estimated incidence of recent infection was thus 9395 per 100,000 for individuals older than 7 years. Peaks of the estimated incidence rate of recent infection were found to be 11561 per 100,000 in age group of 41–50 years and 11428 per 100,000 in the group aged 13–19 years. Conclusions Our study indicated that B.pertussis infections are considerablely common, particularly in adolescents and adults in China. The study also stresses the importance of laboratory diagnosis for pertussis and employment of booster dose of pertussis vaccine in adolescents and adults in this country.

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The precipitation behaviour and age-hardening response of Al-1.5Cu-4.0Mg (wt.%) alloys microalloyed with Si have been investigated by means of hardness measurement, TEM and HRTEM. Compared to the ternary alloy, the quaternary alloys exhibit a higher hardness. It is found that the underaged microstructure in the Al-1.5Cu-4.0 Mg alloy contains some fine precipitates, which are identified as the T phase by FFT spectra. The peak-aged microstructures of the ternary alloy is dominated by the T phase, while the peak-aged microstructures of the Si-containing alloys are dominated by the S phase. The volume fraction of the S phase is found to increase as more Si is added.

Tungsten, an essential refractory metal material, has the characteristics of high melting and boiling points, high hardness, low expansion coefficient, and low vapor pressure. An indirect strategy to print three-dimensional (3D) refractory metal materials via digital light processing (DLP) followed by a post-treatment process was proposed. To analyze this strategy, a transparent ink with tungsten salts was developed, printed into a 3D precursor via DLP, and subsequently transited into 3D porous tungsten. The ultraviolet rheological properties and stability of the ink, transition process from the precursor to a 3D article, and the properties of the obtained 3D porous tungsten were investigated. This ink was preferable for DLP 3D printing, possessing consistency, stability and favorable absorbance at the wavelength of 385 nm. With increasing temperature, the weight of the tungsten salt in the 3D precursor decreased by 8.97% and was transited to tungsten oxide below 460 ℃, reduced to pure nano-sized tungsten at approximately 700 ℃, and finally sintered into porous articles. The organics initially contributed to polymerization during printing as well as reduction as a carbon reducer after pyrolysis. The pore size distribution of porous tungsten is nonlinear or multimodal, depending on the final sintering temperature. At 1200 ℃, two distinct peaks are observed in the pore distribution curves of the products. At 1400 ℃, the small pore as a whole decreases from approximately 100 to 1000 nm. Correspondingly, the relative density of the samples increased with temperature.

Epstein-Barr virus (EBV)-encoded small RNAs (EBER1 and EBER2) are highly expressed in all forms of EBV latency in EBV-associated malignancies. EBER gene variations and their association with EBV-associated disease still remain poorly characterized. To investigate the patterns of EBER gene variations and their roles in tumorigenesis, EBER gene sequences were analyzed by nested-PCR and DNA sequencing in 101 lymphomas from Northern China, a non-nasopharyngeal carcinoma (NPC) endemic area. In addition, EBV type 1 and type 2 classifications were made by using nested-PCR assays across type-specific regions in the EBNA2 gene. EB-6m was the dominant subtype (95.0%, 96/101) in lymphoma. The distribution of the EBER subtypes in the four lymphoma groups was not significantly different (p > 0.05), neither was that of the EBNA2 type (p > 0.05). Compared with previous data in the same area, the distribution of EBER subtypes in lymphoma was similar to that in EBV-associated gastric carcinoma (EBVaGC) and throat washing (TW) from healthy donors (p > 0.05), but was significantly different from that of NPC. The EBNA2 type distribution between lymphoma and the other three groups was significantly different (p < 0.05). The proportion of type 1 and type 2 dual infections was higher in lymphoma than that in GC, NPC and TW. The mutation 7123nt A → T was identified in 11 of 101 (10.9%, 11/101) lymphomas, significantly more than that in EBV-associated gastric carcinomas (EBVaGC) (0%, 0/50) and throat washings (TWs) from healthy donors (3.3%, 3/92) (p < 0.05). These findings indicate that EBER subtypes may not be associated with pathogenesis of lymphoma, but that a point mutation at position 7123nt (A → T) provides a new area for further exploration. Furthermore it is necessary to investigate the role of EBNA2-subtype mixed infections in the establishment of lymphoma.