Northeast Yunnan Research Articles

Analysis of spatial distribution characteristics of A-level tourist attractions in Yunnan Province based on GIS

Based on GIS geographic information technology, this paper analyses and researches the spatial distribution characteristics of tourist attractions in Yunnan Province based on the data of Class A tourist attractions in Yunnan Province in 2022, using the nearest-neighbour index, kernel density analysis, geographic concentration index, imbalance index and Lorenz curve method. The results show that: (1) The spatial distribution type of A-grade tourist scenic spots in Yunnan Province is agglomeration, and the balance is low and the concentration degree is high, and the Lorentz curve shows a significant upward trend. From the perspective of the geographical area of Yunnan Province, the number of A-level tourist attractions in Kunming, Dalizhou, Puer, Qujing and Lijiang exceeds 50% of the province, showing obvious imbalance. (2) The spatial distribution of tourist attractions in Yunnan Province is obviously different, and the overall distribution characteristics of more northwest, less eastern edge, and more central area are mainly concentrated in central Yunnan and western Yunnan, while eastern Yunnan and northeast Yunnan are less distributed.

Origin of Color and Spectral Characteristics of Nanhong Agate from Northeast Yunnan, China

Nanhong agate has attracted public attention as the most distinctive gemstone in China. Owing to the limited data on Nanhong agates from a new production area in northeastern Yunnan, this paper presents the first data from gemological studies on these agates. Complex investigations using Fourier-transform infrared (FTIR) spectrometry, ultraviolet–visible (UV–VIS) luminescence spectrometry, Raman spectroscopy, polarizing microscopy, scanning electron microscopy (SEM), electron microprobe (EPMA), and laser ablation–inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses were carried out to obtain basic data concerning the gemological properties, microstructure, and spectroscopic and geochemical characteristics of this interesting material. The results illustrate that Nanhong agates from northeastern Yunnan are mainly composed of α-quartz and also contain certain amounts of moganite, illite, goethite, and hematite. The typical red (yellow) and white appearance can be attributed to the microstructure of the agates, the contents of Fe and Al impurities, and trace elements. The Raman spectra, microstructure, and chemical composition of the unique “yellow-skinned” agates from northeastern Yunnan are significantly different from those of other types of Nanhong agate. This work lays a foundation for the future identification and research of this type of Nanhong agate.

Mineralogical and geochemical composition of the early carboniferous Li-enriched coals of the Zhaotong coalfield, Northeast Yunnan, China

The Middle and Lower Carboniferous sedimentary sequences in the central and western parts of Guizhou, southwest China, are enriched in bauxite, and are characterized by increased levels of the critical element Li. In the adjacent area (northeastern Yunnan), the Lower Carboniferous sequences contain coal seams. Whether these coal seams are enriched in Li, and the provenance affinity between the bauxites and these coal seams are still unclear. In this study, the mineralogy and geochemistry of the C1 coal seam in the Wanshoushan Formation, Lower Carboniferous sedimentary sequences, Zhaotong Mining Area, northeastern Yunnan Province, were investigated. The results showed that the major minerals in the C1 coal seam are clay minerals, Al-bearing minerals, quartz, pyrite, and so on, most of which are of authigenic origin. This coal seam was enriched in Li, Cu, Zn, and so on with the Li concentration coefficient reaching to 8.92. The trace elements in the C1 coal seam of the Wanshoushan Formation and the elements in the bauxites of the Jiujialu and Dazhuyuan Formations were similar, and their provenance was the underlying Cambrian - Ordovician carbonate rocks.

Ceropegia sunhangiana, a new species of Apocynaceae from Southwest China

Ceropegia sunhangiana P.R.Luo and T.Deng, a new species from Qiaojia, northeast Yunnan, southwest China, is described and illustrated herein based on its morphological characteristics and molecular evidence. This species is similar to C. christenseniana, and C. sinoerecta but can be distinguished easily by its stem, indumentum, leaf, and floral features, especially the corolla shape and size, the corolla tube and lobe characters. Phylogenetic analysis based on ITS, trnL‐trnF, trnS‐trnG, psbA‐trnH and rps16 sequences shows that this new species belongs to C. sect. Chionopegia H.Huber with strong support, which was mutually verified by morphology analyses. A table including the morphological characters of related species and a dichotomous key to all 25 species of Ceropegia in China are provided.

Spatio-temporal characteristics and influencing factors of traditional villages in the Yangtze River Basin: a Geodetector model

The Yangtze River Basin (YRB) is the birthplace of Chinese civilization and is rich in traditional village resources. Studying their spatial distribution characteristics and influencing factors can guide the protection, inheritance, and development of traditional villages in YRB. This study takes 5 batches of 3346 traditional villages in YRB since 2012 as the research object. Using the nearest neighbor index, kernel density analysis, standard deviation ellipse, and Geodetector model, we analyzed the spatial distribution characteristics of traditional villages in YRB and detected their influencing factors. The results show that the distribution of traditional villages in YRB exhibited a spatial pattern of cohesive clusters, forming a high-density area and development center in the junction zone between Guizhou and Hunan provinces and southeast of Anhui Province, and secondary-density areas in Northeast Yunnan Province and east Jiangxi Province. The results of the Geodetector show that the formation of the spatial distribution pattern of traditional villages in YRB is affected by the combined effects of natural and socio-economic factors, among which elevation and NDVI were the main factors, and the interaction of multiple factors showed an enhanced trend. The findings of this study can provide scientific decision-making support for the development and protection of traditional villages in YRB.

Thermodynamic Calculations of Direct Reduction Smelting Technology of Copper Oxide Ores Based on Smelting Slag from the Yubeidi Site, Yunnan Province

The current research on metallurgical remains from scientific excavations in northeast Yunnan from the Bronze Age period is insufficient. In order to study the smelting technology of the Bronze Age in north-eastern Yunnan, samples of slag and mineral excavated from the Yubei Di site in Dongchuan were examined. Based on the outcome of the characterization analysis, a simulation was executed utilizing the software Factsage 7.1 in order to generate a phase diagram that accurately portrays the melting procedure. This simulation aimed to produce the most credible representation of the phase transition by employing computational methods. Characterisation methods included Metallographic Microscopy, Scanning Electron Microscopy Energy Dispersive Spectromicropy (SEM-EDS), X-ray diffraction (XRD), and Radiocarbon Date (14C dating). The results showed that there was much copper ore left in the slag of the site. Most of these copper ores were in the form of copper ferrite or cuprous oxide. The copper ore was copper oxide ore, and metal copper particles appeared in a small amount of the slag. Most of the slags unearthed from the site of the Yubeidi site were products of sulfur-containing oxide reduction and smelting into copper. Based on the outcomes of the simulations, it was established that the slag excavated from the Yubeidi site was mainly from the reduction and smelting process of sulphur-containing copper oxide minerals into copper, without consciously adding fluxes, not having mastered the slag-making techniques for different types of copper ores, and with primitive techniques. The carbon 14 dating results show that the age of the slag was during the Spring and Autumn Period and the Warring States Period.

The Genesis of Pyrite in the Fule Pb-Zn Deposit, Northeast Yunnan Province, China: Evidence from Mineral Chemistry and In Situ Sulfur Isotope

The Fule deposit is a typical Cd-, Ge- and Ga-enriched Pb-Zn deposit located in the southeast of the Sichuan–Yunnan–Guizhou Pb-Zn polymetallic ore province in China. Zoned, euhedral cubic and pentagonal dodecahedral and anhedral pyrites were observed, and they are thought to comprise two generations. First generation pyrite (Py1) is homogeneous and entirely confined to a crystal core, whereas second generation pyrite (Py2) forms bright and irregular rims around the former. Second generation pyrite also occurs as a cubic and pentagonal dodecahedral crystal in/near the ore body or as an anhedral crystal generally closed to the surrounding rock. The content of S, Fe, Co, and Ni in Py1 are from 52.49 to 53.40%, 41.91 to 44.85%, 0.19 to 0.50% and 0.76 to 1.55%, respectively. The values of Co/Ni, Cu/Ni and Zn/Ni are from 0.22 to 0.42, 0.02 to 0.08 and 0.43 to 1.49, respectively, showing that the Py1 was formed in the sedimentary diagenetic stage. However, the contents of S, Fe, Co, and Ni in Py2 are in the range from 51.67 to 54.60%, 45.01 to 46.52%, 0.03 to 0.07% and 0.01 to 0.16%, respectively. The Co/Ni, Cu/Ni and Zn/Ni values of Py2 are from 0.40 to 12.33, 0.14 to 13.70 and 0.04 to 74.75, respectively, which is characterized by hydrothermal pyrite (mineralization stage). The different δ34S values of the Py1 (−34.9 to −32.3‰) and the Py2 (9.7 to 20.5‰) indicate that there are at least two different sources of sulfur in the Fule deposit. The sulfur in Py1 was derived from the bacterial sulfate reduction (BSR), whereas the sulfur in the ore-forming fluids (Py2) was derived from the thermochemical sulfate reduction (TSR). The main reasons for the different morphologies of pyrite in the regular spatial distribution in the Fule deposit are temperature and sulfur fugacity.

The Origin of the Black Shale Series and Bentonites from the Wufeng Formation in the Southwestern Upper Yangtze: Implications for the Convergence of the Yangtze and Cathaysia Blocks in the Late Ordovician

AbstractEarly Paleozoic black organic sediments and bentonites occur widely in the craton basin within the Yangtze block and are generally believed to be genetically related to a specific tectonic setting on the cratonic boundary. However, the intimate relationship between their origins and the dynamic mechanisms are unclear, as exemplified by the genesis of the black shale series and bentonites from the Wufeng Formation during the Ordovician–Silurian transition (OST). In order to reveal the relationship between the Wufeng Formation and the convergence of the Yangtze and Cathaysia blocks (i.e., the intracontinental Kwangsian Orogeny), two stratigraphic sections respectively in Zhaotong area (Northeast Yunnan) and Puyi area (Northwestern Guizhou) that were located in the semi‐restricted inner Yangtze Sea during the OST were systematically studied, on the basis of whole‐rock geochemical composition, pyrite δ34S (δ34Spy), total organic carbon (TOC), stable Sr isotope, pyrite framboid size distribution and zircon U‐Pb age, trace elements. The evidence shows that the paleo‐oceanic environment changed significantly at the turn of the early–late Katian and formed the black shale series in the Wufeng Formation. These acritarch assemblages were formed in the transition process of the Upper Yangtze Basin from passive continental margin basin to foreland basin during this interval. Based on previous research on the genetic relationship between black shale series and plate tectonic movement, a basin‐mountain evolution model suitable for South China in the Late Ordovician is presented. The two bentonites in the Wufeng Formation with U‐Pb ages of 445.5 ± 0.8 Ma and 441.9 ± 2.4 Ma primarily originated from the intermediate–acid volcanic eruption during the collision and convergence between the Yangtze and Cathaysia blocks in the Late Ordovician, the provenance region probably being located in the Jiangnan orogenic belt. Thus, we believe that the appearance of the black shale series and bentonite in the Wufeng Formation at the turn of the early–late Katian may represent the initiation of basin‐mountain transformation and the Kwangsian Orogeny in South China, which provides important evidence for the collision and convergence of the Yangtze and Cathaysia blocks in the Late Ordovician.

Effect of Faults on Shale Pore Fracture and Shale Gas Preservation: A Case Study of the Wufeng-Longmaxi Formation in the Northeast Yunnan Area

Effect of Faults on Shale Pore Fracture and Shale Gas Preservation: A Case Study of the Wufeng-Longmaxi Formation in the Northeast Yunnan Area

A Comparative Analysis of Chinese and English Versions of Red Tourism Texts in Northeast Yunnan——Take Tang Jiyao's Former Residence as an Example

In view of current English version of red cultural tourism texts in Northeast Yunnan, by comparing the Chinese and English versions of red tourism texts in the scenic spot of "Tang Jiyao's Former Residence" from the perspectives of text content, vocabulary, syntactic structure, the paper intends to explores the ways to improve the quality of translation of red tourism texts, so as to make some contributions to the development of the red tourism cultural resources and the realization of sustainable development of the red cultural tourism industry in Northeast Yunnan.

Trace element compositions of sulfides from Pb-Zn deposits in the Northeast Yunnan and northwest Guizhou Provinces, SW China: Insights from LA-ICP-MS analyses of sphalerite and pyrite

Trace elements in sphalerite and pyrite from six deposits at the Sichuan-Yunnan-Guizhou lead–zinc metallogenic province were analysed to constrain the composition, distribution characteristics and substitution mechanisms of trace elements by LA-ICP-MS analyses. The results show that the sphalerites are characterized by high Fe, Ge, Cd and low Bi, Ni, Co and Tl contents, while pyrites characteristically have high contents of Ni, Co, As and low contents of Ge, Ga, Tl, Bi and In. Iron, Ga, Mn, Cd and Ge in sphalerite and Co, Ni and Tl in pyrite are generally lattice-bound, while Ag, Cu, As and Sb are usually present in both micro-inclusions and solid solution. Significant correlations between some elements in sphalerite suggest the substitution mechanisms: 2Zn2+ ↔ (Ag+, Cu+) + (Ga3+, As3+) and 3Zn2+ ↔ 2(Cu+, Ag+) + Ge4+, and the existence of negative correlation between Fe and Mn implies a competition between both elements. The correlation trends between trace elements in pyrite demonstrate the coupled substitution mechanism of 2Fe2+ ↔ (Tl+, Cu+, Ag+) + Sb3+.Generally, darker sphalerite is relatively rich in Fe and Ge compared to light-color sphalerite, and is deficient in Ga, In and Sn. Regionally, the Cu in sphalerite tends to gradually increase from southeast to northwest, and pyrite from Maoping has significantly higher Co and Ti concentrations and Co/Ni ratios than that from the deposits in northwestern Guizhou. The variation of the Co/Ni ratio in pyrite at the scale of these deposits may provide vectors for the geochemical exploration of Pb-Zn mineralization and the Co/Ni ratios close to 0.1 are more prospective for a larger deposit.

Relationship between extreme climate indices and spatiotemporal changes of vegetation on Yunnan Plateau from 1982 to 2019

Extreme weather events have led to significant changes in vegetation over the past few decades. Extreme climate indices and net primary productivity (NPP) of vegetation on Yunnan from 1982 to 2019 were calculated based on Rclimdex 1.0 software and the Carnegie-Ames-Stanford approach (CASA) model, respectively. The relationship between them was studied on annual and monthly scales. The interaction detector was used to calculate the contribution rate of extreme climate factors and synergistic effect on NPP. The results showed that：(1) Annual NPP showed a significant increasing trend in southeast Yunnan, while it showed a decreasing trend in central and northwest Yunnan. (2) Extreme temperature indices (TXx, TXn, TNx, TNn) showed significant increasing trends (P < 0.01), while cold day index (Tx10p) and cold night index (Tn10p) showed significant decreasing trends (P < 0.01), and the warming trend is more obvious. Individual precipitation intensity increases while the continuous precipitation decreases. (3) The correlation between extreme temperature indices and NPP was lower than that between extreme precipitation factors. Extreme precipitation indices had a significant impact on vegetation NPP and dominated the pattern of spatial distribution. Extreme precipitation indices had the excellent explanatory power for the NPP of shrub, grassland, and agricultural vegetation. NPP of Alpine vegetation was remarkably affected by the maximum Tmin (TNx) (q = 0.868). (4) PD values of interactions between extreme climate factors are higher than that of an individual factor. The synergistic effect of extreme climatic factors on NPP in northeast Yunnan is more significant. The interaction between the two extreme climate factors significantly impacts the NPP of agricultural and alpine vegetation. The results may help deeply understand and predict the impact of extreme climate factors on the different sub-regional ecosystems on Yunnan.

Differences in shale gas accumulation process and its significance in exploration of Lower Silurian Longmaxi Formation in Northeast Yunnan

Differences in shale gas accumulation process and its significance in exploration of Lower Silurian Longmaxi Formation in Northeast Yunnan

Remagnetization of Permian Emeishan basalts: Constraints on the timing of native copper mineralization in northeast Yunnan Province, China

New paleomagnetic results from the Permian Emeishan basalts in the Zhaotong area, NE Yunnan province, China show four natural remanent magnetization components. Detailed stepwise thermal demagnetization of basaltic samples from 16 flows from the Dadi section, which represent basalt units III and IV, isolated two groups of characteristic remanent magnetizations. Samples in unit IV (five flows) record a southwest declination and a moderate downward inclination that is considered to be a partial remagnetized remanence. The bottom flows from unit III (11 flows) record a normal polarity direction, interpreted as a remagnetization, which yields a tilt-corrected mean direction of Ds/Is= 8.8°/31.6° (N = 9, ks= 39.7,α95= 8.3°), with a corresponding paleomagnetic pole at 77.1°N, 240.0°E (K = 49.2, A95= 7.4°). The secondary directions have steeper inclinations than primary ones that have been successfully recovered from other studies in this area of the Emeishan basalts. By comparison with the Phanerozoic paleomagnetic poles of the South China Block, the preferred timing of remagnetization is the Lower-Middle Jurassic. Field relationships suggest that the remagnetization of the Emeishan basalts is coeval with the spatially related, but localized, copper mineralization. Thus the timing of the main copper mineralization hosted in the Emeishan basalts is hypothesized to occur in the Early-Middle Jurassic.

Porcine reproductive and respiratory syndrome virus (PRRSV) antibody levels in large swine farms in selected regions of Yunnan province, China

Porcine reproductive and respiratory syndrome (PRRS) is caused by the PRRS virus (PRRSV), and it is a widespread disease that severely affects swine production in all age groups. Detection of PRRSV antibody levels in pig farms is beneficial for immunity evaluations. In this study, a total of 1,206 serum samples of breeding boars, breeding sows, reserve pigs and commercial pigs from 16 large-scale swine farms in 4 different regions of Yunnan province in China were collected during 2019 and detected by indirect enzyme-linked immunosorbent assay (ELISA). The results showed that the average positive rate of PRRSV antibody was 88.32%, among which the antibody-positive rates were 89.03%, 89.18%, 92.11%, and 82.95% in East Yunnan (E. Yunnan), Central Yunnan (Cent. Yunnan), Northwest Yunnan (N.W. Yunnan) and Northeast Yunnan (N.E. Yunnan), respectively (P &gt; 0.05). For the different pig categories, the reserve pigs (93.51%) showed much higher antibody-positive rates, followed by breeding sows (92.44%), commercial pigs (87.34%) and breeding boars (85.62%). Statistical analysis revealed that the rates were significantly different among different pig categories (P &lt;0.05). These s results indicated that pig categories were significantly associated with PRRSV antibody levels in this study. All the positive rates in this study fulfilled the requirement of ≥ 70% set by the National Animal Disease Surveillance Plan of China (2011). The study could provide evidence of the antibody response of PRRSV at the farm level.

Poisonous delicacy: Market-oriented surveys of the consumption of Rhododendron flowers in Yunnan, China

Ethnopharmacological relevancePlants from the family Ericaceae, and in particular those in the genus Rhododendron are frequently reported to contain grayanotoxins. Plant products such as honey and herbal medicines made from these plants occasionally contain grayanotoxins, and in turn may lead to intoxication. The balance between the benefits and risk of poisoning from Rhododendrons is of concerns. This study explores the ethnobotanical knowledge of the people in Yunnan, China as regards the consumption of Rhododendron flowers, and gives special focus to their assessment of the benefit-risk balance. Materials and methodsAn ethnobotanical survey was conducted across 14 county-level local markets in north and central Yunnan province, during which a total of 82 stalls selling Rhododendron flowers were visited and 204 people were interviewed. Voucher specimens were obtained under the guidance of collectors, and details about local practices and knowledge were recorded using semi-structured interviews and participatory observations. ResultsThe consumption of the corollas of Rhododendron decorum Franch. Flowers (RDf) or Rhododendron pachypodum Balf. f. & W.W. Sm. Flowers (RPf) as a seasonal delicacy is a long-standing tradition in the study area. RDf are widely consumed in northwest and northeast Yunnan, while RPf are more prevalent in the central regions of Yunnan, and there is a high consistency in the knowledge of the process for detoxification or palatability for each species. The main reasons for eating the flowers were listed as health benefits (mostly clear heat), wild collected, tradition and good flavor. All RPf consumers stated that the corolla from this species is not toxic, while 67.4% of the RDf consumers claim that the corolla from RDf is toxic. We compared the two species and analyzed their process intensities, poisoning cases and cautions, market trade forms and existing toxicity studies, which agreed well and consistently that the corolla of RDf deserve more toxicity attention than RPf. ConclusionOur study provides a window to look into the ways, beyond honey and herbal medicine, by which Rhododendron species have influenced human wellbeing. The local culture can justify eating Rhododendron flowers, and meanwhile, has developed a series of skills to avoid the side effects of eating them, and therefore the study also provides a good case to answer more general questions about the rationality of eating any plant products by assessing the trade-off between benefits and side effects.

Analysis and Application of Drought Characteristics Based on Theory of Runs and Copulas in Yunnan, Southwest China.

Drought is a complex natural disaster phenomenon. It is of great significance to analyze the occurrence and development of drought events for drought prevention. In this study, two drought characteristic variables (the drought duration and severity) were extracted by using the Theory of Runs based on four drought indexes (i.e., the percentage of precipitation anomaly, the standardized precipitation index, the standardized precipitation evapotranspiration index and the improved comprehensive meteorological drought index). The joint distribution model of drought characteristic variables was built based on four types of Archimedean copulas. The joint cumulative probability and the joint return period of drought events were analyzed and the relationship between the drought characteristics and the actual crop drought reduction area was also studied. The results showed that: (1) The area of the slight drought and the extreme drought were both the zonal increasing distribution from northeast to southwest in Yunnan Province from 1960 to 2015. The area of the high frequency middle drought was mainly distributed in Huize and Zhanyi in Northeast Yunnan, Kunming in Central Yunnan and some areas of Southwest Yunnan, whereas the severe drought was mainly occurred in Deqin, Gongshan and Zhongdian in Northwest Yunnan; (2) The drought duration and severity were fitted the Weibull and Gamma distribution, respectively and the Frank copula function was the optimal joint distribution function. The Drought events were mostly short duration and high severity, long duration and low severity and short duration and low severity. The joint cumulative probability and joint return period were increased with the increase of drought duration and severity; (3) The error range between the theoretical return period and the actual was 0.1–0.4 a. The year of the agricultural disaster can be accurately reflected by the combined return period in Yunnan Province. The research can provide guidelines for the agricultural management in the drought area.

Spatial and Temporal Evolution Characteristics of Drought in Yunnan Province from 1969 to 2018 Based on SPI/SPEI

The objective of this article is to describe the effect of precipitation and temperature on the drought characteristics of Yunnan province in China. The rainfall and temperature data from 10 national meteorological stations in Yunnan province during 1969 to 2018 were used to investigate the spatial and temporal evolution of drought in Yunnan province and the difference of drought index based on Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) at nearly 50a different time scales. The results showed that Yunnan province had a frequent alternation of drought and flood, and the larger the time scale, the gentler the SPI and SPEI changes. The recent 50a drought mainly occurred in 1980–1982, 1988–1990, 2003–2007, and 2010–2015, and there was continuous drought and the duration was prolonged. The changes of SPI and SPEI showed a downward trend in different seasons. The linear slopes of SPI and SPEI in spring, summer, autumn, and winter were − 0.0064, − 0.0088, − 0.0057 and − 0.0.0111, respectively, and the drought trend was the most serious in winter. Continuous spring drought occurred in 2009–2010 and 2012–2014. The SPEI values in 2009–2010 and 2012–2014 were − 0.80, − 0.64, − 0.75, − 1.23, and − 1.17, respectively. The spatial distribution of drought frequency in Yunnan province was greatly different, and its distribution rule was more in the north and east, less in the south and west. The drought frequency in Zhaotong (northeast Yunnan) was the highest at 36.53%, the drought frequency in Deqin and Lijiang (northwest Yunnan) were 33.11% and 33.28%, and the drought frequency in Kunming (central Yunnan) Lincang, Lancang, and Simao (southwest Yunnan) were 29.35%, 30.73%, 32.77%, and 28.35%, respectively. This study provided a scientific basis for revealing the spatial and temporal variation rules, evolution trends, regional drought, and drought impact assessment and risk management of drought in Yunnan province.

Role of community-based active case finding in screening tuberculosis in Yunnan province of China

BackgroundThe barriers to access diagnosis and receive treatment, in addition to insufficient case identification and reporting, lead to tuberculosis (TB) spreads in communities, especially among hard-to-reach populations. This study evaluated a community-based active case finding (ACF) strategy for the detection of tuberculosis cases among high-risk groups and general population in China between 2013 and 2015.MethodsThis retrospective cohort study conducted an ACF in ten communities of Dongchuan County, located in northeast Yunnan Province between 2013 and 2015; and compared to 136 communities that had passive case finding (PCF). The algorithm for ACF was: 1) screen for TB symptoms among community enrolled residents by home visits, 2) those with positive symptoms along with defined high-risk groups underwent chest X-ray (CXR), followed by sputum microscopy confirmation. TB incidence proportion and the number needed to screen (NNS) to detect one case were calculated to evaluate the ACF strategy compared to PCF, chi-square test was applied to compare the incidence proportion of TB cases’ demography and the characteristics for detected cases under different strategies. Thereafter, the incidence rate ratio (IRR) and multiple Fisher’s exact test were applied to compare the incidence proportion between general population and high-risk groups. Patient and diagnostic delays for ACF and PCF were compared by Wilcoxon rank sum test.ResultsA total of 97 521 enrolled residents were visited with the ACF cumulatively, 12.3% were defined as high-risk groups or had TB symptoms. Sixty-six new TB patients were detected by ACF. There was no significant difference between the cumulative TB incidence proportion for ACF (67.7/100000 population) and the prevalence for PCF (62.6/100000 population) during 2013 to 2015, though the incidence proportion in ACF communities decreased after three rounds active screening, concurrent with the remained stable prevalence in PCF communities. The cumulative NNS were 34, 39 and 29 in HIV/AIDS infected individuals, people with positive TB symptoms and history of previous TB, respectively, compared to 1478 in the general population. The median patient delay under ACF was 1 day (Interquartile range, IQR: 0–27) compared to PCF with 30 days (IQR: 14–61).ConclusionsThis study confirmed that massive ACF was not effective in general population in a moderate TB prevalence setting. The priority should be the definition and targeting of high-risk groups in the community before the screening process is launched. The shorter time interval of ACF between TB symptoms onset and linkage to healthcare service may decrease the risk of TB community transmission. Furthermore, integrated ACF strategy in the National Project of Basic Public Health Service may have long term public health impact.

Pressure–dependent fracture permeability of marine shales in the Northeast Yunnan area, Southern China

A series of pressure–dependent permeability experiments were conducted on the Lower Silurian Longmaxi organic–rich shales in northeast Yunnan area, southern China, to investigate the effects of sedimentary bedding, fracture surface roughness, fracture offset, fracture aperture and effective pressure on shale permeability. The results demonstrate that the sedimentary bedding of shale only has a slight influence on matrix permeability, while the fractures can enhance shale permeability dramatically. Even at a maximum effective pressure of 48 MPa, the permeabilities of aligned fractures (without fracture offset) can increase by about one order of magnitude over the permeabilities of the shale matrix. A power–law relation appears to better describe the pressure–dependency of permeability for the tested shale samples than the exponential relationship. The smoother the fracture surface is, the higher the permeability of aligned fractures will be. The fracture offset can improve fracture permeability distinctly. However, the increasing degree of offset fracture permeability is not proportional to the extent of fracture offset. There is a lower pressure sensitivity for offset fracture than aligned fracture. Fracture aperture is the fundamental factor in controlling the fracture permeability, which shows a positive relationship with the cube of fracture aperture. The pressure–dependence of aligned fractures in shale obeys the Walsh permeability model, but the pressure–dependence of offset fractures in shale does not fit well with this model. By combining the experimental results with the geological characteristics of different types of natural fractures, we conclude that the denser vertical intra–formational tension fractures connect with the bed–parallel slip fractures are favorable for step–like migration and enrichment of shale gas in structural highs. The large–scaled high–angle shear fractures likely damage the preservation conditions of shale gas, which is harmful to shale gas enrichment.