Evaluation of Coefficients of Variation for Clinical Chemistry Tests Based on Internal Quality Control Data Across 5,425 Laboratories in China From 2013 to 2022.

Background: Clinical chemistry tests are most widely used in clinical laboratories, and diverse measurement systems for these analyses are available in China. We evaluated the imprecision of clinical chemistry measurement systems based on internal QC (IQC) data. Methods: IQC data for 27 general chemistry analytes were collected in February each year from 2013 to 2022. Four performance specifications were used to calculate pass rates for CVs of IQC data in 2022. Boxplots were drawn to analyze trends of CVs, and differences in CVs among different groups were assessed using the Mann-Whitney U-test or Kruskal-Wallis test. Results: The number of participating laboratories increased significantly from 1,777 in 2013 to 5,425 in 2022. CVs significantly decreased for all 27 analytes, except creatine kinase and lipase. Triglycerides, total bilirubin, direct bilirubin, iron, and γ-glutamyl transferase achieved pass rates >80% for all goals. Nine analytes with pass rates <80% based on 1/3 allowable total error were further analyzed; the results indicated that closed systems exhibited lower CVs than open systems for all analytes, except total protein. For all nine analytes, differences were significant between tertiary hospitals and non-tertiary hospitals and between accredited and non-accredited laboratories. Conclusions: The CVs of IQC data for clinical chemistry have seen a continuous overall improvement in China. However, there is ample room for imprecision improvement for several analytes, with stricter performance specifications.

Coupling strength of human-natural systems mediates the response of ecosystem services to land use change.

Addressing the dynamics of human-natural systems (HNS) driven by land use change (LC) is a key challenge for the sustainable development of ecosystem services (ES). However, how changes to the HNS coupling relationships affect ES is rarely reported. We used network analysis methods to construct an HNS correlation network in the Loess Plateau based on the correlation between the main components of HNS, such as ES, human factors, landscape pattern, vegetation cover, climate change and geomorphic characteristics, and quantitatively described the HNS coupling relationships through key network attributes. We analyzed the variation in HNS network attributes and their relationships with ES along an LC intensity gradient. The results show that carbon storage and soil conservation in the Loess Plateau increased by 0.56% and 0.26%, respectively, during the study period, while the habitat quality and water yield decreased by 0.11% and 0.18%, respectively. An increase in LC intensity reduces connectivity and density in the HNS network, which results in looser connections among HNS components. Importantly, we found that HNS network attributes explained 85% of ES variation across different LC intensity gradients and that connectivity and density had the strongest explanatory power. This means that LC mainly affects ES dynamics by changing the coupling strength of HNS. Our research offers a new perspective for linking LC-HNS-ES, which will help guide practitioners toward establishing and maintaining the sustainability of human well-being amidst changing HNS.

Dramatic shift in the drivers of ecosystem service trade-offs across an aridity gradient: Evidence from China's Loess Plateau.

Increased aridity creates challenges for sustainable ecosystem management due to the potential for trade-offs among ecosystem services. However, our understanding of how ecosystem service trade-offs (EST) respond to aridification remains limited. Here, generalized additive models and structural equation modeling were used to explore EST dynamics within an aridity gradient on the Loess Plateau, China. Trade-offs between water yield and both carbon storage and habitat quality showed nonlinear relationships with aridity, first increasing and then decreasing. Interestingly, climatic and human factors mostly indirectly influenced EST via effects on landscape characteristics. In regions with an Aridity Index (AI) value of <0.5, climatic and human factors strongly drove EST; in regions with AI > 0.5, landscape characteristics were most important. Therefore, landscape characteristics acted as the key regulators of EST. Importantly, AI values of ∼0.5 represented a transition point, after which dramatic shifts in EST-driver relationships were observed. As >22 % of the Earth's terrestrial surface is projected to reach this level of aridity by 2100, further research on this boundary (between sub-humid and semi-arid areas) is urgently needed to protect ecosystems from the effects of increasing aridity. This study may serve as a valuable reference for mitigating the potential negative effects of increased aridity on human well-being.

A New Practical Tool for Assessing the Analytical Performance and Designing Risk-Based Statistical Quality Control Procedures in Laboratories.

BACKGROUND: We developed a new practical tool and applied it to assess the performance of 14 biochemical assays and designed risk-based statistical quality control (SQC) procedures. METHODS: Two graphs were combined to develop the new tool. Data points of assays were plotted on the tool to determine their sigma performance and the risk-based SQC procedures. The quality goal index (QGI) was also calculated for quality improvement. RESULTS: Among 14 assays, total bilirubin, direct bilirubin, alanine aminotransferase, creatine kinase, and gammaglutamyl transferase achieved 6-sigma performance, the recommended SQC procedure was 13s rule (n = 2) with a run size of 1,000 patient samples. Triglycerides was 5-sigma quality and could be controlled with 13s/22s/R4s multi-rule procedure (n = 2) with a run size of 450. Uric acid, creatinine, total cholesterol, and aspartate aminotransferase obtained 4-sigma quality and could be controlled using 13s/22s/R4s/41s multi-rule procedure (n = 4) with run size of 200. The performance for urea, alkaline phosphatase, amylase, and lactate dehydrogenase was 3-sigma and 13s/22s/R4s/41s/6X multi-rule procedure (n = 6) with run size of 45 was recommended. The QGI for assays with sigma quality below 6.0 were all less than 0.8. CONCLUSIONS: The developed tool can be used to simplify laboratory practices in assessing analytical performance and designing SQC procedures.

Application of biological variation and sigma metrics to evaluate the performance of HbA1c in external quality assessment.

BACKGROUND: It is crucial to improve the accuracy of HbA1c measurement as its essential role in diabetes diagnosis and treatment. We aimed to establish the biological variation (BV) and sigma metrics (SM) models and apply the models to evaluate the analytical performance of HbA1c in external quality assessment (EQA) program. METHODS: Data of HbA1c EQA (2021) and internal quality control (IQC) (March-August 2021) were collected. The group-specific bias and coefficient of variance (CV) were computed for measuring systems with laboratory number >9 in EQA program. The analytical bias and CV for individual laboratory were estimated from EQA and IQC data. The CV% and bias% were plotted in the BV-SM models for performance evaluation of measuring system and individual laboratory. RESULTS: Totally, 380 laboratories participated in EQA program. The overall inter-laboratory CV of five EQA samples ranged from 3.02% to 3.63%. There were five measuring systems that met the minimum performance for 5/5 samples: Arkary, Primus, Roche, Mindray and Tosoh, but none of them achieved the optimum performance. Half of the 196 laboratories that reported IQC and EQA results simultaneously achieved 3σ and minimum performance limits. Further analysis indicated that 88.8%, and 31.6% of the laboratories met the minimum performance for bias and CV, respectively. CONCLUSIONS: The biological variation and sigma metrics are appropriate quality management models for evaluating the performance of HbA1c in EQA program. The intra-laboratory and inter-laboratory imprecision need to be improved in order to achieve the required analytical goals for diabetes diagnosis.

Dynamic characteristics of soil aggregate stability and related carbon and nitrogen pools at different developmental stages of plantations in northern China.

The carbon and nitrogen reserves of forest soil play a key role in combating global climate change. Afforestation is considered an effective measure for increasing carbon and nitrogen reserves in terrestrial forest ecosystems. However, the mechanisms governing how different developmental stages of plantations affect soil carbon and nitrogen stability and storage remain unclear. In this study, we selected three developmental stages of the Larix principis-rupprechtii plantations: medium mature forest (30 yr), near mature forest (40 yr) and mature forest (50 yr). We studied the distribution and stability of soil aggregates at distinct developmental stages, the distribution of carbon and nitrogen pools related to aggregates, and their relationship to environmental factors. We found that with increasing forest age, the soil sand particles became finer. In each developmental stage, the proportion of aggregates >0.25 mm reached more than 85%. The concentrations of carbon and nitrogen in the soil aggregates were lower in the near mature forest (40 a) than in the medium mature forest (30 a), but reached a maximum in the mature forest (50 a). There were significant positive correlations between soil carbon and nitrogen concentrations and soil relative water content (RWC), forest age, and stand density. Soil texture strongly affected the distribution of aggregates. TOC/TN was mainly influenced by aggregate distribution, which was most vulnerable to environmental factors. Environmental factors have a significant negative impact on soil texture, and the path coefficient was -0.812. Environmental factors indirectly affected the concentrations of soil carbon and nitrogen by influencing the distribution and stability of soil aggregates. Therefore, different developmental stages of plantations strongly affected forest carbon and nitrogen pools by changing the soil structure and environmental factors. This study provides a basis for understanding the mechanisms of forest soil carbon and nitrogen storage.

Network analysis reveals the regulatory effect of mixed stands on ecosystem structure and functions in the Loess Plateau, China.

Afforestation, an important measure for ecological restoration, has been implemented all over the world, but fragile ecosystem structures and climate change endanger its ecological functions. One major obstacle to optimizing ecological function has been quantifying and characterizing a complex ecosystem structure. Here, the structure and functions of six types of land-use restoration were investigated in the hilly-gully region of the Loess Plateau, China. In total, 44 ecological factors from canopy, understory and soil were determined. We constructed the related network of reforestation ecosystems, quantified the structure of ecosystem through network topology, and explored the relationships between structure and functions. The results showed that changes in plantation type altered the network hubs, but some nodes, such as species height, breast-height diameter and understory biomass, were often keystone hubs. Mixed plantations enhanced the connectivity among different modules. In addition, we found that closeness of network connectivity was an important factor influencing ecological functions, while soil erodibility was the main limiting factor for reforestation ecosystem structure in this region. Moreover, mixed plantations tended to have more balanced topological metrics and ecological functions. Overall, this study suggests that mixed plantations or monoculture plantations should be designed according to the characteristics and ecological demands of the regional ecological environment. Although monoculture plantations may support local ecosystems, mixed plantations offer more resilience to a landscape because they were help to achieve a balance among the ecological functions.

Three years' experience of quality monitoring program on pre-analytical errors in china.

BACKGROUND: Various errors in the procedure of specimen collection have been reported as the primary causes of pre-analytical errors. The aim of this study was to monitor and assess the reasons and frequencies of rejected samples in China. METHODS: A pre-analytical external quality assessment (EQA) scheme involving six quality indicators (QIs) was conducted from 2017 to 2019. Rejection rate was calculated for each QI. The difference of the rejection rates over the time was checked by Chi-square test. Furthermore, the 25th, 50th, and 75th percentiles of the results from total laboratories each year were calculated as optimum, desirable, and minimum level of performance specifications. RESULTS: In total, 423 laboratories submitted data continuously for six EQA rounds. The overall rejection rates were 0.2042%, 0.1709%, 0.1942%, 0.1689%, 0.1593%, and 0.1491%, respectively. The most common error was sample hemolysed (0.0514%-0.0635%), and the least one was sample not received (0.0008%-0.0014%). A significant reduction in percentages was observed for all QIs. For biochemistry and immunology, hemolysis accounted for more than half of the rejection causes, while for hematology, the primary cause shifted from incorrect fill level to sample clotted. The quality specifications had improved over time, except for the optimum level. CONCLUSION: The significant reduction in error rates on sample rejection we observed suggested that laboratories should pay more attention to the standardized specimen collection. We also provide a benchmark for QIs performance specification to help laboratories increase awareness about the critical aspects in the need of improvement actions.

National survey on delta checks in clinical laboratories in China.

Background This study aimed to understand the status quo of delta checks in Chinese clinical laboratories through a nationwide online survey. Methods The survey was divided into two parts. The first part was a general situation survey in which clinical laboratories had to provide information about the laboratories, including delta checks used. In the second part, clinical laboratories were asked to record the delta check alerts generated in their laboratories from June 1st, 2019 to June 30th, 2019. Results The most frequently used analytes in delta checks were potassium (K), glucose (Glu), creatinine (Cre) for clinical chemistry and hemoglobin (Hgb), platelet (PLT) count and white blood cell (WBC) count for clinical hematology. The median maximum time interval between specimens for all analytes was 5 days. The most commonly used delta check calculation modes in Chinese clinical laboratories were percentage change and absolute change. K and Hgb were the analytes most involved in clinical chemistry and clinical hematology delta check alerts. The most common causes of delta check alerts were that the patients had received treatment, which was followed by the change in the patient's physiological state and interference from hemolysis, lipemia and icterus. The two most common outcomes of delta check alerts were 'no problems found, standard report issued' and 'no problems found, report issued with comment'. Conclusions This study was the first nationwide survey of delta checks in China, the results of which help us to understand the current situation of delta checks in Chinese clinical laboratories.

A 3-year-long investigation of the authenticity of the return results of hepatitis B virus qualitative testing in external quality assessment in East China.

BACKGROUND: In external quality assessments (EQAs), it is important and necessary for participants to return authentic test results. However, to obtain better evaluation results, some laboratories have lacked confidence that their own and have preferred to rely upon the test results in surrounding laboratories. These violations covered up errors during testing and affected the authenticity of the returned data. The occurrence of violations in EQA launched by different EQA organizers is still unknown because these violations were carried out in private. In this paper, we adjusted the hepatitis B virus (HBV) qualitative EQA schemes to uncover some of the violations by using specially designed sample combinations in four EQA surveys to show the authenticity and accuracy of HBV testing in some prefectures of East China. METHODS: Four HBV qualitative EQA surveys were selected from 2016 to 2018, which were named 201602, 201701, 201702, and 201801, and a total of 474 laboratories were included. In the first two EQA surveys, the same EQA sample combinations were distributed. In the last two EQA surveys, three kinds of different sample combinations were designed and distributed with specific plans. The result of adding different sample combinations was that each laboratory only had a 33.3% chance of receiving the same sample combinations as those received by the surrounding laboratories. In addition, the laboratories were not aware that those samples with the same serial numbers might have different concentrations and target values. The sample concentrations, mode of delivery, requirements, results reports, and evaluation criteria were all the same as those of the first two EQA surveys. RESULTS: The number of laboratories with failed tests increased from fourfold to sevenfold between the first two and the last two EQA surveys. The number of failed tests in 201702 was eight times that in 201701 during the same year. Six (6 of 469, 1.28%) and three (3 of 472, 0.64%) poor performer laboratories (PPLabs) appeared in 201602 and 201701, respectively, while the number of those laboratories increased to 29 (29 of 474, 6.12%) in 201702 and 201801. Failed tests from PPLabs accounted for 70.5% (201702) and 68.7% (201801) of the total failed tests. The increase in the number of PPLabs was not universal but was concentrated in some prefectures. CONCLUSIONS: The current EQA results for HBV qualitative testing were not as good as originally anticipated. Violations during the EQA surveys caused by exchanging test results with other laboratories and by modifying results before returning still occurred in some prefectures of East China. The laboratories that were in violation can be partly exposed as PPLabs by providing different kinds of sample combinations. Through such an EQA adjustment, the laboratory would have to re-establish confidence in its own testing results from HBV EQA samples. Then, evaluations of HBV qualitative testing samples in EQA would be more authentic and accurate in East China.

Analysis and evaluation of the external quality assessment results of quality indicators in laboratory medicine all over China from 2015 to 2018.

Background This study aimed to comprehensively evaluate laboratory quality in China and explore factors affecting laboratory errors through analyzing the external quality assessment (EQA) results of quality indicators (QIs). Methods According to model 3 (interpretive) of the proficiency testing scheme, the National Center for Clinical Laboratories of China (CNCCL) developed a questionnaire for 15 QIs. Clinical laboratories from different provinces of China participated in the EQA program of QIs annually and submitted data via an online reporting system named Clinet-EQA. The results of QIs were expressed in percentage and sigma value or minute. Three levels of quality specifications (QSs) were defined based on percentile values. Furthermore, the QIs were analyzed by disciplines, hospital scales and information construction levels of participant laboratories. Results A total of 3450 laboratories nationwide continuously attended the EQA program and submitted complete data from 2015 to 2018. The performance of most QIs has improved year by year. QIs in post-analytical gained the best performance with sigma values that varied from 5.3σ to 6.0σ. The comparison of results among different disciplines showed significant differences for five QIs. More than half of QIs had statistical differences among different hospital scales measured by hospital grades and number of hospital beds. The performance of nine QIs were influenced by information construction levels of participant laboratories. Conclusions The overall laboratory quality in China has improved since the initiation of EQA program for QIs, but the performance of some QIs was still unsatisfactory. Therefore, laboratories should make efforts for continuous quality improvement based on information provided by QSs.

Response of soil organic carbon and nitrogen to nitrogen deposition in a Larix principis-rupprechtii plantation.

Plant growth and ecosystem production are limited by nitrogen (N), however, the mechanisms of N limitation in terrestrial carbon (C) sequestration in soil remains unclear. To examine these mechanisms N was deposited at rates of 0, 50, 100, and 150 kg N ha-1 yr-1 for two years in a subalpine Larix principis-rupprechtii plantation. Soil C and N components were measured three times encompassing the entire growing season (spring, summer, and autumn) in the second year of the experiment. Results showed that N-deposition affected soil organic carbon (SOC) in the upper soil layer (0-10 cm) especially in the summer season. Dissolved organic carbon (DOC) played the key role in C loss under the high-N treatment (p < 0.01) with higher N-deposition significantly increasing both DOC and DOC/SOC in summer (p < 0.01). In the summer season when there was sufficient precipitation and higher temperatures, the average DOC across all treatments was higher than spring and autumn. The active C components contributed to SOC sequestration in low and medium N- treatment and DOC, DON dynamics in summer were responsible for the C and N pool loss under the high N-treatment.

Defense pattern of Chinese cork oak across latitudinal gradients: influences of ontogeny, herbivory, climate and soil nutrients.

Knowledge of latitudinal patterns in plant defense and herbivory is crucial for understanding the mechanisms that govern ecosystem functioning and for predicting their responses to climate change. Using a widely distributed species in East Asia, Quercus variabilis, we aim to reveal defense patterns of trees with respect to ontogeny along latitudinal gradients. Six leaf chemical (total phenolics and total condensed tannin concentrations) and physical (cellulose, hemicellulose, lignin and dry mass concentration) defensive traits as well as leaf herbivory (% leaf area loss) were investigated in natural Chinese cork oak (Q. variabilis) forests across two ontogenetic stages (juvenile and mature trees) along a ~14°-latitudinal gradient. Our results showed that juveniles had higher herbivory values and a higher concentration of leaf chemical defense substances compared with mature trees across the latitudinal gradient. In addition, chemical defense and herbivory in both ontogenetic stages decreased with increasing latitude, which supports the latitudinal herbivory-defense hypothesis and optimal defense theory. The identified trade-offs between chemical and physical defense were primarily determined by environmental variation associated with the latitudinal gradient, with the climatic factors (annual precipitation, minimum temperature of the coldest month) largely contributing to the latitudinal defense pattern in both juvenile and mature oak trees.

Preliminary probe of quality indicators and quality specification in total testing process in 5753 laboratories in China.

BACKGROUND: The aim of the study was to promote the establishment and implementation of quality indicators (QIs) in clinical laboratories, catch up with the state of art, and provide preliminary quality specifications for established QIs. METHODS: Clinical laboratories from different provinces in China were included in this QIs survey in 2015. All participants were asked to collect data related to QIs and complete QIs questionnaires. Defect percentages and sigma values were calculated for each QI. The 25th percentile, median, and the 75th percentile of defect percentages and TATs were calculated as optimum, desirable and minimum quality specifications. While 25th, median, and 75th of sigma values were calculated as minimum, desirable and optimum quality specifications, respectively. RESULTS: Five thousand seven hundred and fifty-three clinical laboratories from 28 provinces in China participated in this survey. Median defect percentages of pre-examination QIs varied largely from 0.01% (incorrect sample container) to 0.57% (blood culture contamination) with sigma values varied from 4.0σ to 5.1σ. Median defect percentages of examination phase QIs were all really high. The most common problem in examination phase was test uncovered by inter-laboratory comparison (86.67%). Defect percentages of critical values notification and timely critical values notification were all 0.00% (6.0σ). While the median of defect percentages of incorrect laboratory reports was only 0.01% (5.4σ). CONCLUSIONS: Improvements are needed in all phases of total testing process (TTP) in laboratories in China, especially in examination phase. More attention should be paid when microbiology specimens are collected and results are reported. Quality specifications can provide directions for laboratories to make effort for.

Sigma metric analysis for performance of creatinine with fresh frozen serum.

BACKGROUND: Six sigma provides an objective and quantitative methodology to describe the laboratory testing performance. In this study, we conducted a national trueness verification scheme with fresh frozen serum (FFS) for serum creatinine to evaluate its performance in China. METHODS: Two different concentration levels of FFS, targeted with reference method, were sent to 98 laboratories in China. Imprecision and bias of the measurement procedure were calculated for each participant to further evaluate the sigma value. Quality goal index (QGI) analysis was used to investigate the reason of unacceptable performance for laboratories with σ < 3. RESULTS: Our study indicated that the sample with high concentration of creatinine had preferable sigma values. For the enzymatic method, 7.0% (5/71) to 45.1% (32/71) of the laboratories need to improve their measurement procedures (σ < 3). And for the Jaffe method, the percentages were from 11.5% (3/26) to 73.1% (19/26). QGI analysis suggested that most of the laboratories (62.5% for the enzymatic method and 68.4% for the Jaffe method) should make an effort to improve the trueness (QGI > 1.2). Only 3.1-5.3% of the laboratories should improve both of the precision and trueness. CONCLUSIONS: Sigma metric analysis of the serum creatinine assays is disappointing, which was mainly due to the unacceptable analytical bias according to the QGI analysis. Further effort is needed to enhance the trueness of the creatinine measurement.

[Responses of soil microbial carbolic metabolism characteristics to home-field advantage of leaf litter decomposition in Liaoheyuan Nature Reserve of northern Hebei Province, China].

Using litter bag method, we studied the responses of soil microbial biomass carbon (MBC), microbial respiration (MR) and microbial metabolic quotient (qCO2) in 0-5 cm, 5-10 cm and 10-20 cm soil layers to home-field advantage of Betula platyphlla and Quercus mongolica leaf litter decomposition in Liaoheyuan Nature Reserve, northern Hebei Province. The results showed that the contents of MBC in Betula platyphila and Quercus mongolica leaf litter treatments in home environment (Bh and Qh treatments) were significant higher than that in B. platyphlla and Q. mongolica leaf litter treatments in non-home environment (Ba and Qa treatments). There was no significant difference in MR between home and non-home environments. Response degree of MBC and MR to home-field advantage of different litter decomposition was inconsistent. The MBC of the different soil layers in Qa treatment fell by 39.6%, 34.9% and 33.5% compared to Qh treatment, respectively, and that in B. platyphlla treatment was decreased by 31.6%, 27.1% and 17.0%, respectively. MR of the different soil layers in Qa treatment accounted for 96.3%, 92.4% and 83.7% of Qh treatment, respectively, while MR in B. platyphila treatment was 99. 4%, 97. 3% and 101.3%, respectively. In contrast to MBC, qCO2 in soil showed a reverse pattern. Our study suggested that rich nutrients in soil enhanced microbial activity and weakened the conflict of nutrient uptake between plants and microorganisms, which led to the result that MBC and qCO2 had an obvious response to home-field advantage of litter decomposition, when litter decomposed in its home environment. There was a weak response between MR and home-field advantage of litter decomposition, because of influence of soil temperature, water content and their interaction. Furthermore, MBC, MR and qCO2 had a higher response degree to home-field advantage of Q. mongolica litter than B. platyphila litter, since lower quality litter exhibited higher home-field advantage of litter decomposition.

Maximum temperature accounts for annual soil CO2 efflux in temperate forests of Northern China.

It will help understand the representation legality of soil temperature to explore the correlations of soil respiration with variant properties of soil temperature. Soil temperature at 10 cm depth was hourly logged through twelve months. Basing on the measured soil temperature, soil respiration at different temporal scales were calculated using empirical functions for temperate forests. On monthly scale, soil respiration significantly correlated with maximum, minimum, mean and accumulated effective soil temperatures. Annual soil respiration varied from 409 g C m(-2) in coniferous forest to 570 g C m(-2) in mixed forest and to 692 g C m(-2) in broadleaved forest, and was markedly explained by mean soil temperatures of the warmest day, July and summer, separately. These three soil temperatures reflected the maximum values on diurnal, monthly and annual scales. In accordance with their higher temperatures, summer soil respiration accounted for 51% of annual soil respiration across forest types, and broadleaved forest also had higher soil organic carbon content (SOC) and soil microbial biomass carbon content (SMBC), but a lower contribution of SMBC to SOC. This added proof to the findings that maximum soil temperature may accelerate the transformation of SOC to CO2-C via stimulating activities of soil microorganisms.

[Responses of soil microbial carbon metabolism to the leaf litter composition in Liaohe River Nature Reserve of northern Hebei Province, China].

Using litter bag method, we studied the effects of single and mixed litters from Betula platyphlla, Populus davidiana and Quercus mongolica on soil microbial biomass carbon (MBC), microbial respiration (MR) and microbial metabolic quotient (qCO2) in 0-5, 5-10 and 10-20 cm soil layers. The results showed that the average contents of MBC in 0-20 cm soil layer were 124.84, 325.29, 349.79 and 319.02 mg . kg-1 in the leaf litter removal treatment, Betula platyphlla treatment, Populus davidiana treatment and Quercus mongolica treatment, and the corresponding average rates of MR were 0.66, 1.12, 1.16 and 1.10 µg . g-1 . h-1, respectively. Meanwhile, in 0-20 cm soil layer, the average contents of MBC in the treatments with single leaf litter, mixed litter of two plant species and mixed litter of three plant species were 331. 37, 418. 52 and 529. 34 mg . kg-1, and the corresponding average rates of MR were 1.13, 1.30 and 1.46 µg . g-1 . h-1, respectively. In contrast to the MBC and MR, qCO2 in soil showed a reverse pattern. Our study suggested that characteristics of microbial carbolic metabolism were influenced by litter quality. Namely, the treatment with high litter quality had higher MBC, MR and utilization efficiency of soil carbon, compared with the treatment with low litter quality. Moreover, mixture of different species of leaf litter improved soil microbial activities, increased utilization efficiency on soil carbon and promoted diversity of microbial metabolic pathways, which could then contribute to maintaining and enhancing soil quality of forestland.

National survey on appropriateness of clinical biochemistry reporting in China.

BACKGROUND: Accurate and reliable testing reports play an important role in the prevention, diagnosis, treatment and prognosis of disease. However, little is known about the appropriateness of laboratory testing reporting in China. This national survey takes clinical biochemistry as an example to investigate the state of reporting appropriateness in our country. METHODS: An electronic questionnaire was sent to 1209 laboratories. The participants were asked to retrospectively evaluate the error rates of the following quality indicators: report template integrity, report content filling integrity, report delay, report recall, non-conformities between instrument and laboratory information system (LIS) data, non-conformities between report and request, report notification error, and report modification. Mann-Whitney and Kruskal-Wallis tests were used to identify the potential impacts of reporting appropriateness. RESULTS: A total of 662 of the 1209 laboratories (55%) submitted the survey results, with three returning incomplete data. For the integrity of the report, only 31% of the laboratories had a complete report template that contained all of 21 elements. In addition, the overall error rate of content filling integrity was 45.9% for 19,770 pieces of reports. The overall σ-values of other six quality indicators were all >4, and no significant difference was found among different departments. Group comparison suggested that reporting electronically had a better performance. CONCLUSIONS: The laboratory reporting system in China needs to improve, particularly the integrity of the report. Strengthening information technology will not only promote reporting appropriateness, but also guarantee accurate, standardized and traceable data collection and long-term monitoring.

Patterns of biomass and carbon distribution across a chronosequence of Chinese pine (Pinus tabulaeformis) forests.

Patterns of biomass and carbon (C) storage distribution across Chinese pine (Pinus tabulaeformis) natural secondary forests are poorly documented. The objectives of this study were to examine the biomass and C pools of the major ecosystem components in a replicated age sequence of P. tabulaeformis secondary forest stands in Northern China. Within each stand, biomass of above- and belowground tree, understory (shrub and herb), and forest floor were determined from plot-level investigation and destructive sampling. Allometric equations using the diameter at breast height (DBH) were developed to quantify plant biomass. C stocks in the tree and understory biomass, forest floor, and mineral soil (0-100 cm) were estimated by analyzing the C concentration of each component. The results showed that the tree biomass of P. tabulaeformis stands was ranged from 123.8 Mg·ha-1 for the young stand to 344.8 Mg·ha-1 for the mature stand. The understory biomass ranged from 1.8 Mg·ha-1 in the middle-aged stand to 3.5 Mg·ha-1 in the young stand. Forest floor biomass increased steady with stand age, ranging from 14.9 to 23.0 Mg·ha-1. The highest mean C concentration across the chronosequence was found in tree branch while the lowest mean C concentration was found in forest floor. The observed C stock of the aboveground tree, shrub, forest floor, and mineral soil increased with increasing stand age, whereas the herb C stock showed a decreasing trend with a sigmoid pattern. The C stock of forest ecosystem in young, middle-aged, immature, and mature stands were 178.1, 236.3, 297.7, and 359.8 Mg C ha-1, respectively, greater than those under similar aged P. tabulaeformis forests in China. These results are likely to be integrated into further forest management plans and generalized in other contexts to evaluate C stocks at the regional scale.