Study on Functional Layout of Forest Health Care Base Based on Visual Effect of Landscape: A Case Study of Beijing Mangshan National Forest Park

In recent years, with the rapid development of forest health care industry in China, the demand for forest health care base, especially the construction of mountain forest health care base, has become increasingly urgent. Based on the spatial analysis function of GIS software and the impact of mountain forest environmental factors on human health, this paper briefly introduces the main site selection requirements and application of mountain forest recreation base, taking Jixian County as an example

Spatial distribution of the persistent organic pollutants across the Tibetan Plateau and its linkage with the climate systems: a 5-year air monitoring study

The Tibetan Plateau (TP) has been contaminated by persistent organic pollutants (POPs), including legacy organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) through atmospheric transport. The exact source regions, transport pathways and time trends of POPs to the TP are not well understood. Here polystyrene–divinylbenzene copolymer resin (XAD)-based passive air samplers (PASs) were deployed at 16 Tibetan background sites from 2007 to 2012 to gain further insight into spatial patterns and temporal trends of OCPs and PCBs. The southeastern TP was characterized by dichlorodiphenyltrichloroethane (DDT)-related chemicals delivered by Indian monsoon air masses. The northern and northwestern TP displayed the greatest absolute concentration and relative abundance of hexachlorobenzene (HCB) in the atmosphere, caused by the westerly-driven European air masses. The interactions between the DDT polluted Indian monsoon air and the clean westerly winds formed a transition zone in central Tibet, where both DDT and HCB were the dominant chemicals. Based on 5 years of continuous sampling, our data indicated declining concentrations of HCB and hexachlorocyclohexanes (HCHs) across the Tibetan region. Inter-annual trends of DDT class chemicals, however, showed less variation during this 5-year sampling period, which may be due to the ongoing usage of DDT in India. This paper demonstrates the possibility of using POP fingerprints to investigate the climate interactions and the validity of using PAS to derive inter-annual atmospheric POP time trends

Effect of Ridge Width on the Lasing Characteristics of Triangular and Rectangular InAs/In0.53Ga0.47As Quantum Well Lasers

The lasing characteristics of InP-based InAs/In0.53Ga0.47As quantum well (QW) lasers with different ridge widths are investigated. Two groups of lasers are grown for comparison, one with active triangular QW regions and the other with rectangular QW regions. Their output powers, characteristic temperatures (T0), external differential quantum efficiencies (ηd) and junction temperatures (Tj) are analyzed and compared. The parameter of ridge width is found to play an important role in the performance of the lasers. In triangular QW lasers, by broadening the ridge width from 8 to 12\ua0μm, output power and ηd of the lasers are decreased for the temperature range of 100–320\ua0K due to heating effect. But by broadening the ridge width from 8 to 100\ua0μm in rectangular QW lasers, output power has about 3.5 time increase at 100\ua0K and ηd also has a little increase for temperatures from 100 to 180\ua0K due to much larger emission area and much faster heat dissipation. Tj, the real temperature of the active region, is also found to have accelerated increase at high injection current and heat sink temperature. Besides, compared to the rectangular QW laser of the same ridge width, the improved thermal performance of triangular QW laser is also demonstrated

Accumulation of perfluoroalkyl compounds in Tibetan mountain snow:temporal patterns from 1980 to 2010

The use of snow and ice cores as recorders of environmental contamination is particularly relevant for per- and polyfluoroalky substances (PFASs) given their production history, differing source regions and varied mechanisms driving their global distribution. In a unique study perfluoroalkyl acids (PFAAs) were analyzed in dated snow-cores obtained from high mountain glaciers on the Tibetan Plateau (TP). One snow core was obtained from the Mt Muztagata glacier (accumulation period of 1980–1999), located in western Tibet and a second core from Mt. Zuoqiupo (accumulation period: 1996–2007) located in southeastern Tibet, with fresh surface snow collected near Lake Namco in 2010 (southern Tibet). The higher concentrations of ∑PFAAs were observed in the older Mt Muztagata core and dominated by perfluorooctanesulfonic acid (PFOS) (61.4–346 pg/L) and perfluorooctanoic acid (PFOA) (40.8–243 pg/L), whereas in the Mt Zuoqiupu core the concentrations were lower (e.g., PFOA: 37.8–183 pg/L) with PFOS below detection limits. These differences in PFAA concentrations and composition profile likely reflect the upwind sources affecting the respective sites (e.g., European/central Asian sources for Mt Muztagata and India sources for Mt Zuoqiupu). Perfluorobutanoic acid (PFBA) dominated the recent surface snowpack of Lake Namco which is mainly associated with India sources where the shorter chain volatile PFASs precursors predominate. The use of snow cores in different parts of Tibet provides useful recorders to examine the influence of different PFASs source regions and reflect changing PFAS production/use in the Northern Hemisphere

Mixed infection of Bartonella and Eperythrozoon in a dog - case report

ABSTRACT A March male Golden, weighing 7.6kg, presented with gradual weight loss, high body temperature, depression, poor appetite and thirst, and vomiting before consultation. The results showed that the erythrocytes, hematocrit, hemoglobin, and platelets were lower than the reference values. The diagnosis of mixed infection with haematocrit and eosinophilic bodies was confirmed by real-time fluorescence PCR of whole blood, which was positive for haematocrit and eosinophilic bodies. The dog was treated with doxycycline and ceftriaxone, and the dog fully recovered after 2 weeks with blood transfusion, symptomatic treatment, and supportive therapy. This indicates that the disease can be treated well by a comprehensive treatment approach

Optimization and evaluation of multi-bed adsorbent tube method in collection of volatile organic compounds

The feasibility of using adsorbent tubes to collect volatile organic compounds (VOCs) has been demonstrated since the 1990's and standardized as Compendium Method TO-17 by the U.S. Environmental Protection Agency (U.S EPA). This paper investigates sampling and analytical variables on concentrations of 57 ozone (O-3) precursors (C-2-C-12 aliphatic and aromatic VOCs) specified for the Photochemical Assessment Monitoring Station (PAMS). Laboratory and field tests examined multi-bed adsorbent tubes containing a sorbate combination of Tenax TA, Carbograph 1 TD, and Carboxen 1003. Analyte stabilities were influenced by both collection tube temperature and ambient O-3 concentrations. Analytes degraded during storage, while blank levels were elevated by passive adsorption. Adsorbent tube storage under cold temperatures (- 10 degrees C) in a preservation container filled with solid silica gel and anhydrous calcium sulfate (CaSO4) ensured sample integrity. A high efficiency (> 99%) O-3 scrubber (i.e., copper coil tube filled with saturated potassium iodide [KM removed O-3 (i.e., < 200 ppbv) from the air stream with a sampling capacity of 30 h. Water vapor scrubbers interfered with VOC measurements. The optimal thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) desorption time of 8 min was found at 330 degrees C. Good linearity (R-2 > 0.995) was achieved for individual analyte calibrations (with the exception of acetylene) for mixing ratios of 0.08-1.96 ppbv. The method detection limits (MDLs) were below 0.055 ppbv for a 3 L sample volume. Replicate analyses showed relative standard deviations (RSDs) of < 10%, with the majority of the analytes within < 5%