Finite element method, as a verified numerical simulation method, has been widely applied in the biomechanical research of clear aligner treatment. The accuracy of its calculation results is closely related to the construction method of the finite element model. This paper takes the finite element modeling process of clear aligner treatment as a clue, and reviews the modeling methods of relevant research in recent years, aiming to provide reference for subsequent studies.

Finite element method, as a verified numerical simulation method, has been widely applied in the biomechanical research of clear aligner treatment. The accuracy of its calculation results is closely related to the construction method of the finite element model. This paper takes the finite element modeling process of clear aligner treatment as a clue, and reviews the modeling methods of relevant research in recent years, aiming to provide reference for subsequent studies.

Multiple primary lung cancer (MPLC) refers to lung cancer in which two or more primary lesions occurred simultaneously or successively in different parts of the same patient's lungs. The diagnosis interval is 6 months. MPLC is divided into synchronous MPLC (sMPLC) and metachronous MPLC (mMPLC). sMPLC and intrapulmonary metastasis (IM) are different in treatment strategies and prognosis. However, there are many controversies about the distinction between the two in clinical practice. This article summarizes the current main methods of diagnosing MPLC, and focuses on the latest research progress in distinguishing MPLC from IM. It aims to provide a theoretical basis for accurate diagnosis and treatment of patients with multifocal lung cancer.
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OBJECTIVETo describe the distribution of zinc (Zn) and copper (Cu) in urine samples of generalpopulation in eight provinces of China, to analyze their characteristics of distribution between different region, gender and age-cohorts, and to provide the baseline of themetabolites in the general population.

METHODSFrom 2009 to 2010, 18 120 subjects from the general population aged from 6 to 60 years old were recruited from 24 areas among 8 provinces of China mainland by random sampling. The environmental and physical condition characteristics were collected from questionnaires, and urine samples were collected at the mean time. The levels of Zn and Cu in urine were measured using ICP-MS. Data were analyzed by statistical methods to compare the distribution characteristics of Zn and Cu among populations with different ages and genders.

RESULTSTotally, the median of Cu and Zn in urine were 9.28 and 115.47 µg/L respectively; and the inter-quartile range of Cu and Zn were 2.66-16.09 and 35.32-265.15 µg/L respectively. The median of Cu in male and female were 9.90 and 8.60 µg/L (Z=-5.63, P<0.001), and Zn in male and female were 140.44 and 95.27 µg/L (Z=-14.79, P<0.001). The median of Cu among the groups aged 6-12, 13-16, 17-20, 21-30, 31-45 and 46-60 years old were 9.30, 10.14, 9.67, 9.33, 8.38 and 8.74 µg/L (χ2=70.94, P<0.001), respectively, and the median of Zn 130.83, 132.07, 139.34, 109.3, 78.74 and 109.51 µg/L ((χ2=146.00, P<0.001), respectively.There was statistically significant differences in urinary Cu and Zn levels between male and female, and among the different age groups.

CONCLUSIONThe Cu and Zn levels and distribution in urine among general population between 2009 and 2010 in China were reported in this article. These basic data in China will provide scientific and reliable reference for further scientific research.

Adolescent ; Adult ; Age Factors ; Child ; China ; Copper ; urine ; Environment ; Female ; Humans ; Male ; Middle Aged ; Sex Factors ; Surveys and Questionnaires ; Zinc ; urine

OBJECTIVETo investigate the level of zinc (Zn) and copper (Cu) in whole blood among general population from 8 provinces in China, and to analyze the characteristics of distribution among different regions.

METHODSThis cross-sectional study was performed in 8 provinces from eastern, middle and western China between 2009 and 2010, including 13 110 subjects from 24 regions, and the blood and urine samples were collected. The ICP-MS was applied to test the content of ICP-MS in blood samples, and the results were used to analyze the characteristics of contents and distributions of Zn and Cu among population from different ages, genders and regions groups.

RESULTSTotally, the mean (95%CI) contents of Cu and Zn in blood were 795 (791-799)µg/L and 3 996(3 976-4 015) µg/L, respectively. The characteristics of distribution of Cu content were as followed, the content of males were lower than it of females (male:767 µg/L; female: 822 µg/L, t = -13.302, P < 0.01). The contents of blood Cu in groups of people aging 6-12, 13-16, 17-20, 21-30, 31-45 and 46-60 years old were separately 860(853-868), 758(748-769), 734(728-734), 782(774-790), 811(795-827) and 820(815-826) µg/L. The differences showed statistical significance (F = 78.77, P < 0.01). The blood Cu content of people in eastern China (800µg/L) were also significantly higher than it in middle (774 µg/L)and western China (782 µg/L) (F = 10.94, P < 0.01). Distribution of blood Zn content showed characteristics as follows: the Zn content was higher in males than in females (male 4 085 µg/L and female 3 908 µg/L, t = 8.78, P < 0.01). The contents of blood Zn in groups of people aging 6-12, 13-16, 17-20, 21-30, 31-45 and 46-60 years old were separately 3 306 (3 261-3 350), 3 888 (3 839-3 937), 3 948 (3 902-3 994), 4 272(4 228-4 315), 4 231(4 180-4 281) and 4 250 (4 205-4 294)µg/L, which showed significant statistical differences (F = 233.68, P < 0.01). The blood Zn content of people in eastern China (3 938 µg/L) were significantly lower than it in middle (4 237 µg/L)and western China (4 105 µg/L) (F = 53.16, P < 0.01). In addition, the study also compared the relation between content of Cu and Zn and the frequency of eating seafood. The results found that the frequency of eating seafood could influence the content of Cu and Zn (Cu: F = 13.54, P < 0.01; Zn: F = 200.20, P < 0.01).

CONCLUSIONThe contents and distributions of Cu and Zn in blood differs among people from different groups in ages, genders and regions. The baseline data of this study provided reliable scientific evidence for further research.

Adolescent ; Adult ; Child ; China ; epidemiology ; Copper ; blood ; Cross-Sectional Studies ; Female ; Humans ; Male ; Middle Aged ; Young Adult ; Zinc ; blood

OBJECTIVETo assess the levels of polycyclic aromatic hydrocarbons monohydroxy metabolites in urine of general population in China among 8 provinces, provide the baseline of the metabolites in the general population.

METHODSFrom 2009 to 2010, 18 120 subjects of general population aged 6-60 years old were recruited from 24 areas among 8 provinces in east, west and central areas of China mainland by cluster random sampling. The information of the living environment and health condition were collected by questionnaire and spot urine samples were collected, 4 680 urine samples were analysed by high performance liquid chromatography with tandem mass spectrometry, and monohydroxy metabolites distribution in urine among groups of gender and ages were analysed.

RESULTSGeometric means (GM) of 2-naphthol, 1-naphthol, 3-phenanthrol and 1-hydroxypyrene concentration in urine (95%CI) were 1.85 (1.75-1.95), 1.55 (1.50-1.61), 0.57 (0.54-0.59) and 0.82 (0.78-0.85) µg/L, respectively;and median are 2.44, <0.50, 0.72 and 0.90 µg/L, respectively. The concentration between male and female were significantly different (P < 0.01), and the concentration among the groups of population were significantly different (P < 0.01), the GM of 2-naphthol among the groups of population aged 6-12, 13-16, 17-20, 21-30, 31-45 and 46-60 years old were 1.60, 1.56, 1.69, 2.23, 1.91 and 1.86 µg/L (χ(2) = 17.90, P < 0.01), the GM of 1-naphthol in the groups were 1.30, 1.16, 1.53, 1.68, 1.80 and 1.52 µg/L (χ(2) = 76.22, P < 0.01), the GM of 3-phenanthrol in the groups were 0.78, 0.76, 0.55, 0.42, 0.50 and 0.99 µg/L (χ(2) = 66.48, P < 0.01), the GM of 1-hydroxypyrene in the groups were 0.77,0.64, 1.00, 0.84, 0.84 and 0.57 µg/L (χ(2) = 51.48, P < 0.01), respectively.

CONCLUSIONThe distribution of monohydroxy metabolites levels in urine of general population were different, it provided a basic data for the further study of polycyclic aromatic hydrocarbons biomonitoring in the population.

Adolescent ; Adult ; Child ; China ; epidemiology ; Cross-Sectional Studies ; Environmental Exposure ; Female ; Humans ; Male ; Middle Aged ; Naphthols ; urine ; Polycyclic Aromatic Hydrocarbons ; urine ; Pyrenes ; urine ; Sentinel Surveillance ; Young Adult

OBJECTIVETo evaluated the levels of arsenic (As) in blood and urine among general population in China and analyze its influencing factors.

METHODSA total of 18 120 subjects from general population aged 6-60 years were recruited from 24 districts in 8 provinces in eastern, central and western China mainland from 2009 to 2010, by cluster random sampling method. Blood samples and urine samples were collected, the information of the life-style was collected by questionnaire.Inductive coupled plasma mass spectrometry was applied to test the As level in the samples, and the distribution of As in blood and urine for different ages, genders, areas and life habits were then analyzed.

RESULTSThe geometric mean (GM) of blood As concentration among general population was 2.33 µg/L;the GM of blood As in male (2.35 µg/L) was higher than and female (2.30 µg/L) (Z = -1.42, P < 0.05); from eastern, central to western China, the blood As level were 2.94, 1.30 and 0.98 µg/L (χ(2) = 643.22, P < 0.05) , respectively; the GM in smokers (2.84 µg/L) was higher than non-smokers (2.27) (Z = -6.28, P < 0.05) ;the seafood consumer had a higher blood As level (2.59 µg/L) than people not consuming seafood (1.47 µg/L) (Z = -23.68, P < 0.05). The urine As level of the whole population was 13.72 µg/L;while its GM in male (14.10 µg/L) was higher than female (13.33 µg/L) (Z = -3.94, P < 0.05); the values from eastern, central to western China were 14.14, 16.02 and 9.57 µg/L (χ(2) = 353.89, P < 0.05), respectively;the level in smokers (16.06 µg/L) was higher than nonsmokers (13.70 µg/L) (Z = -2.63, P < 0.05); the level in seafood consumers (14.82 µg/L) was higher than people not consuming seafood (10.99 µg/L) (Z = -3.20, P < 0.05). The blood As level had a positive correlation with urine As level (correlation coefficient:0.285, P < 0.05).

CONCLUSIONThe As level in blood and urine varied by gender and area among general population in China, and related to life-styles. There was a positive correlation between As level in blood and that in urine.

Adolescent ; Adult ; Arsenic ; blood ; urine ; Child ; China ; epidemiology ; Cross-Sectional Studies ; Environmental Exposure ; Female ; Humans ; Male ; Middle Aged ; Sentinel Surveillance ; Young Adult

OBJECTIVETo evaluate the levels of lead (Pb) and cadmium (Cd) in blood and urine among general population in China, and thereby analyze their prevalent features.

METHODSA total of 18 120 subjects from general population aged 6-60 years were recruited from 24 districts in 8 provinces in eastern, central and western China mainland from 2009 to 2010, by cluster random sampling method. The blood samples and urine samples of these people were collected. The questionnaire survey was used to collect the information of the living environment and health conditions.Inductive coupled plasma mass spectrometry was applied to test the Pb and Cd levels in the samples, and the distribution of Pb and Cd in blood and urine for different ages, genders, areas and life habits were then analyzed.

RESULTSAmong the general population in China, the geometric mean (GM) of blood Pb concentration was 34.9 µg/L; the GM of blood Pb in male and female groups were 40.1 and 30.4 µg/L (Z = -28.05, P < 0.05), respectively; the GM from eastern, central and western China were 31.2, 38.8 and 58.9 µg/L (χ(2) = 1 483.33, P < 0.05) , respectively. The GM of urine Pb of the whole population was 1.05 µg/L;while the GM in male and female groups were 1.06 µg/L and 1.05 µg/L (Z = -0.73, P > 0.05) , respectively;the values from eastern, central and western China were 0.76, 2.85 and 3.22 µg/L (χ(2) = 1 982.11, P < 0.05), respectively. The GM of blood Cd concentration among general population was 0.49 µg/L; and the values in male and female group were 0.60 and 0.41 µg/L (Z = -11.79, P < 0.05) , respectively; the GM from eastern, central and western China were 0.45, 0.65 and 0.67 µg/L (χ(2) = 69.87, P < 0.05), respectively; the GM of urine Cd concentration of the whole population was 0.28 µg/L, while the GM in male and female groups were 0.29 and 0.28 µg/L (Z = -3.86, P < 0.05), respectively; the values from eastern, central and western China were 0.29,0.42 and 0.18 µg/L (χ(2) = 402.76, P < 0.05), respectively. the Spearman's rank correlation coefficient for Cd in blood and Cd in urine was 0.22, for Pb in blood and Pb in urine was 0.21. Both the correlations were statistic significant (P < 0.05).

CONCLUSIONThe Pb and Cd levels in blood and urine were relatively higher among general population in China varying by gender and area. There were positive correlations between Pb and Cd levels in blood and those in urine.

Adolescent ; Adult ; Cadmium ; blood ; urine ; Child ; China ; epidemiology ; Cross-Sectional Studies ; Environmental Exposure ; Female ; Humans ; Lead ; blood ; urine ; Male ; Middle Aged ; Sentinel Surveillance ; Young Adult

OBJECTIVETo evaluated the manganese (Mn), cobalt (Co) and molybdenum (Mo) levels in blood and urine among general population in China, and thereby to analyze their prevalent features.

METHODSFrom 2009 to 2010, a total of 18 120 subjects of general population aged 6-60 years were recruited from 24 districts in 8 provinces in eastern, central and western China mainland, by cluster random sampling method. The information about their living environment and health status were collected by questionnaire, and their blood and urine samples were also collected.Inductive coupled plasma mass spectrometry (ICP-MS) was applied to test the Mn, Co and Mo levels of blood and urine samples, and the Mn, Co, Mo distribution in blood and urine among groups of population in different ages and genders were then analyzed.

RESULTSAmong general population in China, the geometric mean (GM) of Mn concentration in blood was 8.98 µg/L. The Mn concentration in blood among males and females were separately 8.14 µg/L and 9.88 µg/L (Z = -18.84, P < 0.01). The GM of Mn concentration in urine was 0.63 µg/L. The Mn concentration in urine among males and females were separately 0.62 µg/L and 0.63 µg/L (Z = -0.67, P > 0.05). The geometric mean (GM) of Co concentration in blood was 0.194 µg/L. The Co concentration in blood among males and females were separately 0.166 µg/L and 0.225 µg/L (Z = -23.04, P < 0.01). The GM of Co concentration in urine was 0.282 µg/L. The Co concentration in urine among males and females were separately 0.260 µg/L and 0.307 µg/L (Z = -7.35, P < 0.01). The GM of Mo concentration in blood was 0.25 µg/L. The Mo concentration in blood among male and female group were separately 0.27 µg/L and 0.23 µg/L (Z = -5.03, P < 0.01). The GM of Mo concentration in urine was 27.7 µg/L. The Mo concentration in urine among males and females were 29.8 µg/L and 25.6 µg/L (Z = -6.31, P < 0.01), respectively.

CONCLUSIONThe Mn, Co and Mo levels in blood and urine varied by gender and area among general population in China, the study provided basic data evidence for the following Mn, Co and Mo biological monitoring studies in near future.

Adolescent ; Adult ; Child ; China ; epidemiology ; Cobalt ; Environmental Exposure ; Environmental Monitoring ; Female ; Humans ; Male ; Manganese ; Middle Aged ; Molybdenum

Objective To evaluated the manganese (Mn), cobalt (Co) and molybdenum (Mo) levels in blood and urine among general population in China , and thereby to analyze their prevalent features.Methods From 2009 to 2010, a total of 18 120 subjects of general population aged 6-60 years were recruited from 24 districts in 8 provinces in eastern , central and western China mainland , by cluster random sampling method.The information about their living environment and health status were collected by questionnaire , and their blood and urine samples were also collected.Inductive coupled plasma mass spectrometry ( ICP-MS) was applied to test the Mn , Co and Mo levels of blood and urine samples , and the Mn, Co, Mo distribution in blood and urine among groups of population in different ages and genders were then analyzed.Results Among general population in China , the geometric mean ( GM) of Mn concentration in blood was 8.98 μg/L.The Mn concentration in blood among males and females were separately 8.14 μg/L and 9.88 μg/L ( Z =-18.84, P <0.01 ).The GM of Mn concentration in urine was 0.63 μg/L.The Mn concentration in urine among males and females were separately 0.62 μg/L and 0.63 μg/L ( Z =-0.67, P >0.05 ).The geometric mean ( GM ) of Co concentration in blood was 0.194 μg/L.The Co concentration in blood among males and females were separately 0.166 μg/L and 0.225 μg/L ( Z =-23.04, P <0.01 ).The GM of Co concentration in urine was 0.282 μg/L.The Co concentration in urine among males and females were separately 0.260μg/L and 0.307μg/L ( Z=-7.35, P<0.01).The GM of Mo concentration in blood was 0.25μg/L.The Mo concentration in blood among male and female group were separately 0.27 μg/L and 0.23 μg/L ( Z =-5.03, P <0.01 ).The GM of Mo concentration in urine was 27.7 μg/L.The Mo concentration in urine among males and females were 29.8 μg/L and 25.6μg/L (Z=-6.31,P<0.01), respectively.Conclusion The Mn, Co and Mo levels in blood and urine varied by gender and area among general population in China , the study provided basic data evidence for the following Mn , Co and Mo biological monitoring studies in near future.