世界军事领域依赖于纺织品

虽说纺织工业不能提供全世界军事领域中所需的坦克、武器或弹药等装备,但毫无疑问的是军事领域也不能没有纺织品。事实上,军事力量一直依赖于纺织品,包括军服、运输附件、睡眠休息装备以及其他数不清的物品。     

Poly(3-hexadecylthiophene)/montmorillonite clay nanocomposites: Influence of preparation and type of clay on their structures

A nanocomposite of poly(3-hexadecylthiophene) (PHDT) with montmorillonite (MMT) was prepared by in situ polymerization (PHDT/MMT) and nanocomposites of PHDT with organomontmorillonite clay (OrgMMT) were prepared by both in situ polymerization (PHDT/OrgMMT) and by the solvent casting method (PHDT/OrgMMT-sc). The nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). PHDT/OrgMMT was also characterized by transmission electron microscopy (TEM). FTIR spectra indicate the presence of the clay in the polymer matrices and show variations on the frequency of the Si–O–Si stretching vibration. The XRD diffractograms indicate that PHDT/MMT and PHDT/OrgMMT-sc are intercalated nanocomposites, while PHDT/OrgMMT is mostly exfoliated, but present also some intercalation, as confirmed by TEM.     

Using computational fluid dynamics to improve the drag coefficient estimates for tall buildings under wind loading

Wind is the main horizontal force acting on tall buildings. This force is proportional to the drag coefficient. The drag coefficient is an important factor in their structural design. Designers have historically relied upon experimental wind tunnel results to estimate the drag coefficient. However, this process is both expensive and time consuming. In this study, we alternatively computed the drag coefficient (apart from the pressure, force, and bending moment) using computational fluid dynamics for a typical 93‐m‐high residential building. The simulation considers the actual building geometry, as well as the neighborhood roughness effects. We compared these results with the conventional estimates contained in the Brazilian code NBR‐6123/1988 and Eurocode EC1. The results indicated that the pressures obtained herein near the top of the building were lower compared to those obtained using conventional estimation methods given in codes. Comparatively, the obtained bending moment relative to the base of the building was higher, indicating the existence of significant drag forces not considered in codes. In fluid dynamics simulations, the drag coefficient is determined for each terrain condition. Computational fluid dynamics can effectively simulate the drag force and resultant forces in the direction of the flow, as well as the vortices that result during coating detachment and other types of damage.     

Erythema migrans-like rash illness at a camp in North Carolina: a new tick-borne disease?

BACKGROUND: Borrelia burgdorferi, the causative agent of Lyme disease, has never been isolated from a patient thought to have acquired Lyme disease in any southeastern state. OBJECTIVE: To investigate 14 cases of an erythema migrans (EM)-like rash illness that occurred during 2 summers at an outdoor camp in central North Carolina in an effort to determine the etiologic, epidemiological, and clinical aspects of this illness. METHODS: Using active surveillance, we identified cases of clinically diagnosed EM in residents and staff of the camp. We collected clinical and demographic information; history of exposure to ticks; acute and convalescent serum antibodies to B. burgdorferi, Rickettsia rickettsii, and Ehrlichia chaffeensis; and cultures for spirochetes from biopsy specimens of skin lesions. Serum samples from a group of residents and staff who did not develop rashes were tested for the same antibodies. We speciated ticks removed from people and collected from vegetation. RESULTS: We identified 14 cases of EM-like rash illness during the 2 summers. Of the 14 case-patients, 10 had associated mild systemic symptoms and 1 had documented fever. All 14 case-patients had removed attached ticks, and 8 remembered having removed a tick from the site where the rash developed a median of 12 days earlier (range, 2-21 days). One tick removed from the site where a rash later developed was identified as Amblyomma americanum, the Lone Star tick; 97% of ticks collected from vegetation and 95% of ticks removed from people were A. americanum. No spirochetes were isolated from skin biopsy specimens. Paired serum samples from 13 case-patients did not show diagnostic antibody responses to B. burgdorferi or other tick-borne pathogens. CONCLUSIONS: This investigation suggests the existence of a new tick-associated rash illness. We suspect that the disease agent is carried by A. americanum ticks. In the southern United States, EM-like rash illness should no longer be considered definitive evidence of early Lyme disease.     

Well differentiated cerebellar tissue within a mature cystic teratoma

OBJECTIVE: Oesophageal self-expanding metal endoprostheses (SEMS, or stents) are recognized as a safe means of palliating dysphagia caused by malignancy. Stent designs that have covered or uncovered walls are now available. The purpose of this study was to compare the outcome of use of these two designs. DESIGN: Thirty consecutive cases were reviewed. All the patients had been referred over a period of 25 months for palliation of dysphagia caused by malignant obstruction. Either a covered or an uncovered stent was placed in each patient. Palliation of dysphagia, 30 day mortality, mean survival time, and the number of endoscopic re-interventions required, were assessed. RESULTS: Uncovered Ultraflex stents were used in 14 patients, and Schneider Wallstents were used in 16 patients. Dysphagia improved by one grade or more in 69% of patients. The 30 day mortality was 27%, with an overall mean survival time of 99 days. There was no significant difference between the two groups for these three parameters. Ten patients needed a total of 28 repeat endoscopic procedures to maintain stent patency, with overall rates for each group of 1.64 procedures per patient, for uncovered stents, compared with 0.31 for covered stents (significant at the P < 0.05 level). The number of repeat procedures increased with survival time. CONCLUSION: The use of covered self-expanding metal oesophageal endoprostheses is associated with a significant reduction in the need for endoscopic reintervention after stent placement.     

Differential protein oxidation in Duchenne and Becker muscular dystrophy

BACKGROUND: The fifth edition of the TNM classification contains a number of changes concerning head and neck tumors. The division of Stage IV tumors into three subcategories marks a significant expansion of the stage grouping procedure. METHODS: In a retrospective study, the clinical courses of 3247 patients with carcinoma of the oral cavity, the oro- and hypopharynx, the larynx, the salivary glands, and the maxillary sinus were comparatively evaluated according to the fourth and fifth editions of the TNM classification agreed upon by the International Union Against Cancer and the American Joint Committee on Cancer. The particular aim of this study was to test the prognostic relevance of the subdivision of Stage IV, especially for mucosal carcinoma. RESULTS: In classifying the primary tumor, the most extensive changes were noted for supraglottic and salivary gland tumors. On the basis of the fourth edition of the TNM classification, the following recurrence free 5-year survival rates for 3033 cases of mucosal cancer were calculated: Stage I, 91.0%; Stage II, 78.6%; Stage III, 61.4%; Stage IV, 31.0%. The calculations based on the fifth edition yielded the following: Stage I, 91.0%; Stage II, 77.2%; Stage III, 61.2%; Stage IVA, 32.4%; Stage IVB, 25.3%; Stage IVC, 3.6%. CONCLUSIONS: The adequacy of the revised stage classification in establishing a prognostic hierarchy was confirmed. However, a significant prognostic distinction between N2 metastasis (Stage IVA) and N3 metastasis (Stage IVB) could not be found.     

Characterization and Physical Explanation of Energetic Particles on Planck HFI Instrument

The Planck High Frequency Instrument (HFI) has been surveying the sky continuously from the second Lagrangian point (L2) between August 2009 and January 2012. It operates with 52 high impedance bolometers cooled at 100 mK in a range of frequency between 100 GHz and 1 THz with unprecedented sensitivity, but strong coupling with cosmic radiation. At L2, the particle flux is about 5 \(\hbox {cm}^{-2}\,\hbox {s}^{-1}\) and is dominated by protons incident on the spacecraft. Protons with an energy above 40 MeV can penetrate the focal plane unit box causing two different effects: glitches in the raw data from direct interaction of cosmic rays with detectors (producing a data loss of about 15 % at the end of the mission) and thermal drifts in the bolometer plate at 100 mK adding non-Gaussian noise at frequencies below 0.1 Hz. The HFI consortium has made strong efforts in order to correct for this effect on the time ordered data and final Planck maps. This work intends to give a view of the physical explanation of the glitches observed in the HFI instrument in-flight. To reach this goal, we performed several ground-based experiments using protons and \(\alpha \) particles to test the impact of particles on the HFI spare bolometers with a better control of the environmental conditions with respect to the in-flight data. We have shown that the dominant part of glitches observed in the data comes from the impact of cosmic rays in the silicon die frame supporting the micro-machined bolometric detectors propagating energy mainly by ballistic phonons and by thermal diffusion. The implications of these results for future satellite missions will be discussed.     

A bacterial consortium isolated from an Icelandic fumarole displays exceptionally high levels of sulfate reduction and metals resistance

The soils of three fumaroles and one mining site, all with high metal content, were surveyed for the presence of metal-resistant sulfate-reducing bacteria and their potential application in the bioremediation of acid mine drainages. By means of selective soil enrichments a bacterial consortium was isolated from an Icelandic fumarole that displayed very high sulfate reduction in the presence of a mixture of 0.75 g/L of Fe, 0.20 g/L of Zn and 0.080 g/L of Cu. Under these conditions the bacterial consortium reduced 91% of the added 3.9 g/L of sulfate after 28 days, precipitating 100% of the Fe, 96% of the Zn and 97% of the Cu during the same time. Both total bacterial numbers and numbers of culturable sulfate-reducing bacteria remained unchanged when grown in media containing metals, suggesting low or absent inhibitory effects of the metals on the bacterial consortium. PCR-DGGE profiles of the sulfate reducing bacterial communities obtained from the Icelandic fumarole sample showed that bacterial diversity decreased significantly after metal addition: from the original 12 ribotypes only two were detected in the metal-tolerant culture. Phylogenetic analysis of 16S ribosomal RNA gene sequences revealed that these two ribotypes were affiliated with the genera Clostridium and Desulfovibrio, with C. subterminale, C. pascui, C. mesophilum and C. peptidovorans and D. desulfuricans identified as their closest relatives.