Dual trajectory of sleep and frail in elderly people. / è€å¹´äººç¡çœ ä¸Žè¡°å¼±åŒè½¨è¿¹.

The high incidence of dual sleep and frail disorders in the elderly people, often occurring together, seriously affects the physical and mental health of the older people, effective research on the dynamics of dual sleep and frail disorders is important for improving the quality of life for the older people and responding to global ageing trend. While trajectory studies provide a unique practical scientific perspective to grasp the dynamics of development, dual trajectories unite dual barriers provide an opportunity to study the dynamic dependence of both sleep and frailty simultaneously sleep trajectories and frailty trajectories in older people are interrelated and interacted through deeper mechanisms. Therefore, it is necessary for the study not only focus on the ongoing development of health problems, but also needs to consider multiple aspects and propose targeted intervention program.

Abnormal changes in functional connectivity between the amygdala and frontal regions are associated with depression in Alzheimer's disease.

PURPOSE: The aim of the present study was to investigate the functional connectivity (FC) of Alzheimer's disease patients with depression (D-AD) based on an amygdalar seed using resting-state functional magnetic resonance imaging (rs-fMRI). METHODS: Twenty-one non-depressed AD (nD-AD) patients and 21 D-AD patients underwent rs-fMRI. The Hamilton Depression Rating Scale and Neuropsychiatric Inventory were used to evaluate the severity of depression. The amygdala was used as the seed for FC analysis. The FC differences between the two groups were evaluated by two-sample t tests, and the correlation of FC changes with depressive severity was analyzed by Pearson correlational analysis. RESULTS: Compared with the nD-AD patients, D-AD patients had increased FC values between the amygdala and orbitofrontal cortex and decreased FC values among the amygdala, medial prefrontal cortex, and inferior frontal gyrus. CONCLUSION: These data suggest that abnormal amygdala-prefrontal FC may be an important characteristic of AD patients with depression.

Altered Intrinsic Coupling between Functional Connectivity Density and Amplitude of Low-Frequency Fluctuation in Mild Cognitive Impairment with Depressive Symptoms.

Neuroimaging studies have demonstrated that major depressive disorder increases the risk of dementia in older individuals with mild cognitive impairment. We used resting-state functional magnetic resonance imaging to explore the intrinsic coupling patterns between the amplitude and synchronisation of low-frequency brain fluctuations using the amplitude of low-frequency fluctuations (ALFF) and the functional connectivity density (FCD) in 16 patients who had mild cognitive impairment with depressive symptoms (D-MCI) (mean age: 69.6 ± 6.2 years) and 18 patients with nondepressed mild cognitive impairment (nD-MCI) (mean age: 72.1 ± 9.7 years). Coupling was quantified as the correlations between the ALFF values and their associated FCDs. The results showed that the ALFF values in the D-MCI group were higher in the left medial prefrontal cortex (mPFC) and lower in the right precentral gyrus (preCG), and the FCD values were higher in the left medial temporal gyrus (MTG) than those in the nD-MCI group. Further, correlation analyses demonstrated that, in the D-MCI group, the mPFC was negatively correlated with the MTG. These findings may relate to the characteristics of mood disorders in patients with MCI, and they offer further insight into the neuropathophysiology of MCI with depressive symptoms.

Complexity and Entropy Analysis of a Multi-Channel Supply Chain Considering Channel Cooperation and Service.

In this paper, based on the background of channel cooperation and service of the supply chain, this paper constructs a Nash game model and a Stackeberg game model in the multi-channel supply chain considering an online-to-store channel (OSC). Based on maximizing the profits and the bounded rationality expectation rule (BRE), this paper builds a dynamic game model, respectively, and analyzes the stability of the equilibrium points by mathematical analysis and explores the influences of parameters on stability domain and entropy of the system by using bifurcation diagram, the entropy diagram, the largest Lyapunov exponent and the chaotic attractor etc. Besides, the influences of service level and profit distribution rate on system's profit are discussed. The theoretical results show that the greater the service level and profit distribution rate are, the smaller the stability domain of the system is; the system will go into chaotic state and the system's entropy will increase when operators adjust her/his price decision quickly; when the manufacturer or the retailer keeps service level in the appropriate value which is conducive to maximizing her/his profit; the manufacturer should carefully set the service level of OSC to ensure the system's profit; in Nash game model, the stability of the system weakens than that in Stackelberg game model. Furthermore, this paper puts forward some suggestions to help the manufacturer and retailer in multi-channel supply chain to do the better decision.

The Complexity and Entropy Analysis for Service Game Model Based on Different Expectations and Optimal Pricing.

The internet has provided a new means for manufacturers to reach consumers. On the background of the widespread multichannel sales in China, based on a literature review of the service game and multichannel supply chain, this paper builds a multichannel dynamic service game model where the retailer operates an offline channel and the manufacturer operates an online channel and offers customers the option to buy online and pick up from the retailer's store (BOPS). The manufacturer and the retailer take maximizing the channel profits as their business objectives and make channel service game under optimal pricing. We carry on theoretical analysis of the model and perform numerical simulations from the perspective of entropy theory, game theory, and chaotic dynamics. The results show that the stability of the system will weaken with the increase in service elasticity coefficient and that it is unaffected by the feedback parameter adjustment of the retailer. The BOPS channel strengthens the cooperation between the manufacturer and the retailer and moderates the conflict between the online and the offline channels. The system will go into chaotic state and cause the system's entropy to increase when the manufacturer adjusts his/her service decision quickly. In a chaotic state, the system is sensitive to initial conditions and service input is difficult to predict; the manufacturer and retailer need more additional information to make the system clear or use the method of feedback control to delay or eliminate the occurrence of chaos.

Abnormal baseline brain activity in Alzheimer's disease patients with depression: a resting-state functional magnetic resonance imaging study.

PURPOSE: As one of the most common mental disorders and the most important precursor of suicide in Alzheimer's disease (AD), depression is associated with a decline in both well-being and daily functioning. At present, the diagnosis of AD patients with depression (D-AD) is largely dependent on clinical signs and symptoms, and the precise neural correlate underlying D-AD is still not fully understood. METHODS: The current study sought to investigate low-frequency oscillations at the voxel level in D-AD patients based on the amplitude of low-frequency fluctuations (ALFF) measured using resting-state functional magnetic resonance imaging. We examined 22 D-AD patients and 21 non-depressed AD (nD-AD) patients. RESULTS: The results revealed that D-AD patients exhibited increased ALFF values in the left caudate and thalamus and decreased ALFF values in the left middle temporal pole compared with nD-AD patients. CONCLUSION: These findings may provide further insight into the underlying neuropathophysiology of AD with depression.

Common 1H-MRS Characteristics in Patients With Alzheimer's Disease and Vascular Dementia Diagnosed With Kidney Essence Deficiency Syndrome: A Preliminary Study.

Context • Traditional Chinese medicine (TCM) indicates that both Alzheimer's disease (AD) and vascular dementia (VD) should be categorized as dementia and that they have a common etiology and pathogenesis under TCM classification of syndromes, such as with kidney essence deficiency syndrome (KEDS). The pathological location is mainly in the brain. However, it remains unclear whether AD and VD patients with KEDS exhibit a metabolic commonality in the same region of the brain. Objective • The study intended to investigate the metabolic characteristics of the brain using proton magnetic resonance spectroscopy (1H-MRS) in patients with AD and VD who had been diagnosed with KEDS. Design • The research team designed a pilot study, with the participants being allocated to 3 groups: (1) an AD group, (2) a VD group, and (3) a control group. All data analysis was carried out by a trained radiologist who was blinded to each participant's diagnosis. Setting • The study took place at the Tongde Hospital of Zhejiang Province (Zhejiang Sheng, China). Participants • Participants were patients at the Tongde Hospital with mild AD or VD who had been diagnosed with KEDS. The normal controls were patients' spouses or guardians with normal cognitive function. Outcome Measures • All participants underwent 1H-MRS. The N-acetyl aspartate (NAA)/myo-inositol (mI), NAA/creatine (Cr), choline (Cho)/Cr, and mI/Cr ratios were bilaterally measured in the posterior cingulate gyrus (PCG) and anterior cingulate gyrus (ACG) by the Syngo spectroscopy postprocessing package. Demographic characteristics and 1H-MRS data were assessed across the AD, VD, and normal control groups. Results • Thirteen patients with mild AD with KEDS, 15 patients with mild VD with KEDS, and 18 normal controls were recruited from May 2013 through May 2014. The AD and VD groups did not significantly differ in the NAA/mI, NAA/Cr, Cho/Cr, and mI/Cr ratios in either the PCG or the ACG, with the exception being the Cho/Cr ratio in the right ACG, for which the ratio of the AD group was significantly lower when compared with that of the VD group (P < .05). Conclusions • Mild AD and VD with KEDS showed similar patterns for the 1H-MRS on the cingulate cortex, providing evidence for a common pathogenesis for the KEDS that is associated with AD and VD, providing a modern biological basis for the philosophy of providing the same treatment for different diseases.

(1)H-MRS asymmetry changes in the anterior and posterior cingulate gyrus in patients with mild cognitive impairment and mild Alzheimer's disease.

Alzheimer's disease (AD) is the most common cause of dementia worldwide. Amnestic mild cognitive impairment (aMCI) is often the prodromal stage to AD. Most patients with aMCI harbor the pathologic changes of AD and demonstrate transition to AD at a rate of 10%-15% per year. Patients with AD and aMCI experience progressive brain metabolite changes. Accumulating evidence indicates that the asymmetry changes of left and right brain happen in the early stage of AD. However, the features of asymmetry changes in both anterior cingulate gyrus (ACG) and posterior cingulate gyrus (PCG) are still unclear. Here, we examine the left-right asymmetry changes of metabolites in ACG and PCG. Fifteen cases of mild AD patients meeting criteria for probable AD of NINDS-ADRDA, thirteen cases of aMCI according to the Mayo Clinic Alzheimer's Disease Research Center criteria, and sixteen cases of age-matched normal controls (NC) received Proton magnetic resonance spectroscopy ((1)H-MRS) for measurement of NAA/mI, NAA/Cr, Cho/Cr, and mI/Cr ratios in the PCG and ACG bilaterally. We analyzed (1)H-MRS data by paired t-test to validate the left-right asymmetry of (1)H-MRS data in the PCG and ACG. In AD, there was a significant difference in mI/Cr between the left and right ACG (P<0.001) and the left and right PCG (P=0.007). In aMCI, there was a significant difference in mI/Cr between the left and right ACG (P<0.001). In NC, there were no differences in the ratio value of metabolites NAA/mI, NAA/Cr, Cho/Cr, and mI/Cr between the left and right ACG and PCG. Thus, the left-right asymmetry of mI/Cr in the ACG and PCG may be an important biological indicator of mild AD.

Neurometabolic characteristics in the anterior cingulate gyrus of Alzheimer's disease patients with depression: a (1)H magnetic resonance spectroscopy study.

BACKGROUND: Depression is a common comorbid psychiatric symptom in patients with Alzheimer's disease (AD), and the prevalence of depression is higher among people with AD compared with healthy older adults. Comorbid depression in AD may increase the risk of cognitive decline, impair patients' function, and reduce their quality of life. However, the mechanisms of depression in AD remain unclear. Here, our aim was to identify neurometabolic characteristics in the brain that are associated with depression in patients with mild AD. METHODS: Thirty-seven patients were evaluated using the Neuropsychiatric Inventory (NPI) and Hamilton Depression Rating Scale (HAMD-17), and divided into two groups: 17 AD patients with depression (D-AD) and 20 non-depressed AD patients (nD-AD). Using proton magnetic resonance spectroscopy, we characterized neurometabolites in the anterior cingulate gyrus (ACG) of D-AD and nD-AD patients. RESULTS: Compared with nD-AD patients, D-AD patients showed lower N-acetylaspartate/creatine (NAA/Cr) and higher myo-inositol/creatine (mI/Cr) in the left ACG. NPI score correlated with NAA/Cr and mI/Cr in the left ACG, while HAMD correlated with NAA/Cr. CONCLUSIONS: Our findings show neurometabolic alterations in D-AD patients. Thus, D-AD pathogenesis may be attributed to abnormal activity of neurons and glial cells in the left ACG.

Long non­coding RNA GHET1 promotes osteosarcoma development and progression via Wnt/ß­catenin signaling pathway.

Osteosarcoma (OS) is known as a malignant tumor with a high mortality rate of children and adults worldwide. Long non­coding RNAs (lncRNAs) have been revealed as oncogenes or tumor suppressors that are involved in the tumorigenesis and metastasis of some types of cancer. However, the biological role of long non­coding RNA gastric carcinoma proliferation enhancing transcript 1 (lncGHET1) and its regulatory mechanism in OS progression have not been elucidated. The aim of the present study was to investigate the role of lncGHET1 in OS. The present study explored lncGHET1 expression using a reverse transcription­quantitative (RT­q)PCR assay. Furthermore, the Cell Counting Kit­8 assay, flow cytometry detection, wound healing and transwell invasion assays were performed to evaluate its biological role and the underlying mechanisms in vitro. Additionally, the effect of lncGHET1 was evaluated in vivo in a xenograft model. lncGHET1 expression was significantly upregulated in OS cell lines compared with in an osteoblastic cell line according to the RT­qPCR assay. The results of a knockdown functional experiment suggested that inhibition of lncGHET1 attenuated cell proliferation, migration, invasion and epithelial­to­mesenchymal transition, and promoted apoptosis, partly through regulating the Wnt/ß­catenin signaling pathway in OS. These findings indicated that lncGHET1 may serve an essential regulatory role in the biological processes of OS. The present study identified a novel therapeutic target for diagnosis and treatment of human OS.

The Stability and Complexity Analysis of a Low-Carbon Supply Chain Considering Fairness Concern Behavior and Sales Service.

This paper studies a low-carbon dual-channel supply chain in which a manufacturer sells products through the direct channel and traditional channel, and a retailer sells products through the traditional channel. The manufacturer considers carbon emission reduction and has fairness concern behavior. The retailer provides sales service in the traditional channel and considers fairness concern behavior. The objective of this paper is to analyze the effects of different parameter values on the price stability and utility of the supply chain system emphatically using 2D bifurcation diagram, parameter plot basin, the basins of attraction, chaos attractor and sensitivity to the initial value, etc. The results find that the retailer's fairness concern behavior shrinks the stability of the supply chain system more than that of the manufacturer's fairness concern behavior. The system stability region decreases with the increase of carbon emission reduction level and the retailer's fairness concern. The customers' preference for the direct channel decreases the stable range of the direct channel, while it enlarges the stable range of the traditional channel. The supply chain system enters into chaos through flip bifurcation with the increase of price adjustment speed. In a stable state, the manufacture improving customer's preference for the direct channel and the retailer choosing the appropriate fairness concern level can achieve the maximum utility separately. In a chaotic state, the average utilities of the manufacturer and retailer all decline, while that of the retailer declines even more. By selecting appropriate control parameter, the low-carbon dual-channel supply chain system can return to a stable state from chaos again. The research of this paper is of great significance to price decisions of participants and supply chain operation management.

The Impacts of Green Innovation Input and Channel Service in a Dual-Channel Value Chain.

This paper constructs a dual-channel value chain composed of one altruistic manufacturer and one altruistic retailer, where the manufacturer makes green innovation input for green products and sells its green products to its customers through both the direct channel and the traditional channel, the retailer provides channel service for customers and sells green products through the traditional channel. We consider two scenarios in which the manufacturer and the retailer make decentralized and centralized decisions, respectively. We develop two dynamic game models for the two scenarios and analyze the dynamic behaviors of the two dynamic game models using bifurcation diagram, LLE (largest Lyapunov exponent) and attraction of basin, etc. We find that the stability region in decentralized decision model is greater than that of centralized decision, and narrow with increase of service value, green innovation input. In the decentralized decision model, the stability of the system decreases with the altruistic behavior increasing. With the price adjustment speed increasing, the dual-channel green value chain system enters into chaotic state through flip bifurcation or N-S bifurcation. In the stable state, the manufacturer and the retailer can obtain the maximum utility with the appropriate value of green innovation input. In the chaotic state, the utilities of the manufacturer and retailer are greatly affected and significantly reduced. This study will provide good guidance for sustainable development decision-making of dual-channel green value chain.

The Abnormal Functional Connectivity between the Hypothalamus and the Temporal Gyrus Underlying Depression in Alzheimer's Disease Patients.

Hypothalamic communication with the rest of the brain is critical for accomplishing a wide variety of physiological and psychological functions, including the maintenance of neuroendocrine circadian rhythms and the management of affective processes. Evidence has shown that major depressive disorder (MDD) patients exhibit increased functioning of the hypothalamic-pituitary-adrenal (HPA) axis. Neurofibrillary tangles are also found in the hypothalamus of Alzheimer's disease (AD) patients, and AD patients exhibit abnormal changes in the HPA. However, little is known of how the hypothalamus interacts with other brain regions in AD patients with depression (D-AD). Functional connectivity (FC) analysis explores the connectivity between brain regions that share functional properties. Here, we used resting-state (rs) magnetic resonance imaging (MRI) technology and the FC method to measure hypothalamic connectivity across the whole brain in 22 D-AD patients and 21 non-depressed AD patients (nD-AD). Our results showed that D-AD patients had reduced FC among the hypothalamus, the right middle temporal gyrus (MTG) and the right superior temporal gyrus (STG) compared with the FC of nD-AD patients, suggesting that the abnormal FC between the hypothalamus and the temporal lobe may play a key role in the pathophysiology of depression in AD patients.

Decreased functional connectivity between the dorsal anterior cingulate cortex and lingual gyrus in Alzheimer's disease patients with depression.

BACKGROUND: Depression is one of the most common psychiatric symptoms in Alzheimer's disease (AD), occurring in up to 40% of AD patients. It influences the cognitive function of patients and increases the burden on their caregivers. Currently, there are few effective medical treatments for reducing the symptoms of depression in AD patients. Understanding the underlying neurobiological mechanisms in AD patients with depression (D-AD) is crucial for developing effective interventions. The anterior cingulate cortex (ACC) is an important brain region involved in emotional and cognitive processing. Several functional magnetic resonance imaging studies have shown that patients with major depressive disorder have structural, functional, and metabolic abnormalities in the ACC. METHODS: We investigated the resting-state functional connectivity (FC) of ACC subregions in 15 D-AD patients and 17 non-depressed AD (nD-AD) patients, by parcellating the ACC into the rostral and dorsal ACC (dACC). RESULTS: Our results revealed that D-AD patients have decreased FC between the dACC and the right occipital lobe and right lingual gyrus, compared with nD-AD patients. CONCLUSIONS: Decreased FC between the dACC and the right occipital lobe and right lingual gyrus may play an important role in the neuropathophysiology of depression in AD.

Fractional amplitude of low-frequency fluctuations is disrupted in Alzheimer's disease with depression.

OBJECTIVE: To explore brain activity in AD with depression (D-AD) based on fractional amplitude of low-frequency fluctuation (fALFF). METHODS: Twenty-two D-AD and 21 AD without depression patients (nD-AD) were examined by magnetic resonance imaging during resting state. Neuropsychiatric Inventory and Hamilton Depression Rating Scale were employed to assess the severity of depression. We analysed the characteristics of fALFF in D-AD differing from nD-AD. We also examined the correlation between fALFF and the depression severity. RESULTS: D-AD patients had higher fALFF in right fusiform gyrus, left caudate nucleus, and right middle temporal gyrus (MTG), meanwhile lower fALFF in supplementary motor area (SMA) than nD-AD patients. CONCLUSIONS: Abnormal fALFF changes in fusiform gyrus, caudate nucleus, MTG and SMA may be important neuropathophysiologic characteristics of depression in AD. SIGNIFICANCE: We have clarified the potential neuropathological changes of depression in AD based on fALFF method, which is crucial for effective intervention.

Abnormal degree centrality in Alzheimer's disease patients with depression: A resting-state functional magnetic resonance imaging study.

Depression is common in Alzheimer's disease (AD) and occurs in AD patients with a prevalence of up to 40%. It reduces cognitive function and increases the burden on caregivers. Currently, there are very few medications that are useful for treating depression in AD patients. Therefore, understanding the brain abnormalities in AD patients with depression (D-AD) is crucial for developing effective interventions. The aim of this study was to investigate the intrinsic dysconnectivity pattern of whole-brain functional networks at the voxel level in D-AD patients based on degree centrality (DC) as measured by resting-state functional magnetic resonance imaging (R-fMRI). Our study included 32 AD patients. All patients were evaluated using the Neuropsychiatric Inventory and Hamilton Depression Rating Scale and further divided into two groups: 15 D-AD patients and 17 non-depressed AD (nD-AD) patients. R-fMRI datasets were acquired from these D-AD and nD-AD patients. First, we performed a DC analysis to identify voxels that showed altered whole brain functional connectivity (FC) with other voxels. We then further investigated FC using the abnormal DC regions to examine in more detail the connectivity patterns of the identified DC changes. D-AD patients had lower DC values in the right middle frontal, precentral, and postcentral gyrus than nD-AD patients. Seed-based analysis revealed decreased connectivity between the precentral and postcentral gyrus to the supplementary motor area and middle cingulum. FC also decreased in the right middle frontal, precentral, and postcentral gyrus. Thus, AD patients with depression fit a 'network dysfunction model' distinct from major depressive disorder and AD.

Regional Coherence Changes in Alzheimer's Disease Patients with Depressive Symptoms: A Resting-State Functional MRI Study.

Alzheimer's disease (AD) is characterized by progressive cognitive decline along with neuropsychiatric symptoms including depression and psychosis. Depression is a common psychiatric disorder occurring in people across the lifespan. Accumulating evidence indicates that depression may be a prodrome and/or a "risk factor" for AD. However, whether AD and depression share a common pathophysiological pathway is still unclear. The aim of this study was to identify regional alterations in brain function associated with depressive symptoms in mild AD patients. Thirty-two mild AD patients were evaluated using the Neuropsychiatric Inventory and Hamilton Depression Rating Scale, and were divided into two groups: 15 AD patients with depressive symptoms (D-AD) and 17 non-depressed AD (nD-AD) patients. Using the approach of regional homogeneity (ReHo), we characterized resting-state regional brain activity in D-AD and nD-AD patients. Compared with nD-AD patients, D-AD patients showed decreased ReHo in the right precentral gyrus, right superior frontal gyrus, right middle frontal gyrus, and right inferior frontal cortex. Our findings show regional brain activity alterations in D-AD patients. Thus, D-AD pathogenesis may be attributed to abnormal neural activity in multiple brain regions.

[Cetyltrimethylammonium bromide for fluorescence enhancement of anhydrotetracycline hydrochloride and iso-tetracycline].

Fluorescence enhancement of anhydrotetracycline hydrochloride and iso-tetracycline has been described. The fluorescence intensities of anhydrotetracycline hydrochloride and iso-tetracycline with cetyltrimethylammonium bromide (CTMAB) enhanced by micellar solution have been examined. It is found that fluorescence enhancement of anhydrotetracycline hydrochloride and iso-tetracycline depends on the concentration of CTMAB and pH of the solution. It can be used to develop sensitive methods for the determination of tetracycline hydrochloride and its decomposition product.

VEGF and EMMPRIN expression correlates with survival of patients with osteosarcoma.

AIM: To investigate the clinicopathologic characteristics of Vascular Endothelial Growth Factor (VEGF) and Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) expression in osteosarcoma, and to evaluate the clinical significance of these two markers in the survival of osteosarcoma. METHODS: VEGF and EMMPRIN expression in paraffin-embedded specimens gathered from 65 patients with primary osteosarcoma were detected by the method of immunohistochemistry using antibodies against VEGF and EMMPRIN. The correlation of VEGF and EMMPRIN expression with the clinicopathologic features and with the survival of osteosarcoma was subsequently assessed. RESULTS: The expression of VEGF and EMMPRIN was detected in 47/65 (72.31%) and 45/65 (69.23%) of patients with osteosarcoma, respectively. Positive expression of VEGF and EMMPRIN was significantly correlated with surgical stage and percentage of dead cells of osteosarcoma. A significant correlation was found between the expression of VEGF and EMMPRIN in osteosarcoma (r=0.89, p=0.01). Additionally, surgical stage, percentage of dead cells, VEGF and EMMPRIN expression showed significant influence on overall survival (OS) and disease-free survival (DFS) in univariate analysis. In multivariate analysis, surgical stage (IIA versus IIB/III) and percentage of dead cells (≤90% versus >90%) were significant for DFS and OS. Those patients with VEGF+/EMMPRIN+ co-expression showed significantly shorter OS and DFS compared with VEGF-/EMMPRIN- expression. CONCLUSION: According to our study, the overexpression of VEGF or EMMPRIN may be an important feature of osteosarcoma. A combined detection of VEGF/EMMPRIN co-expression may benefit us in prediction of a poor survival of osteosarcoma.

[Soluble organic carbon in plant litters on Loess Plateau: content and biodegradability].

The litters of eight plant species from the Loess Plateau were cut into pieces with 2 mm and 1 cm in size, and extracted with distilled water and 0.01 mol x L(-1) CaCl2 to determine the soluble organic carbon (SOC) content. In the meantime, a 7-day indoor incubation test was conducted at (25 +/- 3) degrees C to investigate their biodegradability. The SOC content and the ratio of SOC to total carbon (SOC/TC) in the litters were 18.20-156.82 g x kg(-1) and 4.21%-32.84%, respectively. Shrub litter had a slightly higher SOC content than tree litter, while grass litter had the lowest SOC content. After 7-day incubation, the biodegradation rate of SOC in the plant litters ranged from 44.5% to 80.6% (62.9% on average), and decreased in the order of shrub > tree > grass. By the end of the incubation, the proportion of soluble organic matter in solution had a significant increasing trend, which was related to the rapid biodegradation of labile composition in the litters. The higher content and higher biodegradation rate of SOC in plant litters might play important roles in nutrient cycling and energy flow during the vegetation restoration on Loess Plateau.