Objective:To assess the impacts of abdominal spectral computed tomography (CT) scans on radiation dose in order to validate the feasibility of low-dose spectral CT imaging.Methods:Using varying scanning protocols on the Discovery CT750 HD device, the abdomen of an adult male dose-specific phantom was scanned in two modes: conventional single-energy CT (SECT) and gemstone spectral imaging (GSI). Specifically, the conventional SECT mode featured tube voltages of 120 and 80 kVp, automatic tube current modulation technology, and a noise index (NI) of 10 HU. In contrast, the GSI mode was characterized by the automatic spectral imaging protocol selection (ASIS) technique, rapid switching of the tube voltage between 80 and 140 kVp, and Nis for non-spectral scanning of 8, 10, 15, and 20 HU. Then, various radiation dose metrics and objective image quality were compared across different scanning protocols.Results:In the case of the same NI, the three scanning dose modes (SECT with tube voltages of 120 and 80 kVp, and GSI with a tube voltage of 80/140 kVp) presented similar volume CT dose index (CTDI vol) and dose length product (DLP). However, the SECT with a tube voltage of 80 kVp showed the lowest measured organ absorbed dose ( DT; 5.89 mSv). Effective dose ( E) was determined using DLP and organ DT. The result indicated that, under the three modes except for SECT with a tube voltage of 80 kVp, the E values calculated using DLP were lower than those determinized using the organ DT, with deviations ranging from 9% to 20%. The differences in image noise levels and signal-to-noise ratios (SNR) of the three scanning modes were statistically significant ( F = 65.52, 35.09, P < 0.001). Conclusions:Spectral CT using ASIS technology can achieve low-dose spectral scanning while ensuring image quality.

Objective To analyze the technical movement characteristics of female table tennis play-ers with shoulder impingement syndrome when hitting a forehand topspin loop ball,in order to explore the reasons for shoulder impingement syndrome.Methods Thirteen female table tennis athletes with shoulder impingement syndrome were recruited for the shoulder impingement group(age 20.31±2.56 years,height 165.69±4.00 cm,weight 56.62±6.00 kg)and 13 healthy female table tennis athletes(age 21.54±2.78 years,height 165.54±4.45 cm,weight 60.08±8.02 kg)were selected for the healthy group.Kinematic and electromyographic data of the upper limbs were collected during six tri-als of forehand topspin strokes using a three-dimensional motion capture system and a wireless surface electromyographic system.The data were then averaged and compared between the groups.Results The shoulder impingement group had a greater shoulder flexion angular velocity at the end of the forward swing compared to the healthy group(t=-3.689,P=0.001).In addition,the shoulder impingement group showed significantly smaller trunk torsion angular amplitude(t=2.614,P=0.015)and average an-gular velocity of trunk torsion(t=3.958,P=0.001).Furthermore,the peak activation level of the anteri-or serratus muscle was smaller in the shoulder impingement group compared to the healthy group(t=2.363,P=0.027).Finally,the deactivation duration of both the triceps brachii and brachioradialis mus-cles was shorter in the shoulder impingement group compared to the latter(t=3.705,P=0.002;t=3.29,P=0.004).Conclusion Female table tennis players with shoulder impingement syndrome exhibit the fol-lowing characteristics in their forehand topspin:1)insufficient trunk rotation and premature deactiva-tion of the brachioradialis muscle,which lead to excessive loading on the shoulder during flexion;2)inadequate activation of the serratus anterior muscle,resulting in compromised scapular stability;3)premature deactivation of the triceps brachii muscle,which negatively affects the control of eccentric contraction velocity at the shoulder joint.

ObjectiveTo investigate the effects of foliar fertilizer of nano-calcium carbonate and calcium nitrate tetrahydrate on the agronomic traits， carbohydrate and endogenous hormone contents of Dendrobium officinale planted for 1 year under greenhouse cultivation， in order to provide scientific basis for fertilization to improve the yield and quality of D. officinale. MethodsSingle-factor experimental design was adopted. Starting from early spring， D. officinale was treated with foliar spraying according to corresponding fertilizers. Three treatment groups were established based on different fertilizers， namely， a blank group（clear water）， a nano-calcium carbonate group（0.727 g·L^-1 nano-calcium carbonate water-soluble fertilizer）， and a calcium nitrate tetrahydrate group（1.091 g·L^-1 calcium nitrate tetrahydrate water-soluble fertilizer）. The frequency of spraying was three times per month， and the entire treatment process lasted for nine months. The effects of various treatments on the traits and relative chlorophyll content of D. officinale were dynamically monitored. Sampling was conducted at three specific time points：August 2， 2023， September 8， 2023， and November 1， 2023， respectively. The contents of glucose and mannose in D. officinale stems were determined by high performance liquid chromatography（HPLC）， the content of soluble sugars in D. officinale stems and leaves was determined by phenol method， and enzyme-linked immunosorbent assay（ELISA） was used to detect the concentrations of cytokinin and auxin. ResultsCompared with the blank group， the treatments with nano-calcium carbonate and calcium nitrate tetrahydrate could significantly increase stem length， stem node number， leaf number， and tiller number. Among them， during the harvesting period in November， the stem length and tiller number， which are indicators related to the yield of D. officinale， increased by 60.85% and 19.23% after treatment with calcium nitrate tetrahydrate， and by 32.54% and 28.85% after treatment with nano-calcium carbonate， respectively. Compared with the blank group， treatments with nano-calcium carbonate and calcium nitrate tetrahydrate could promote the accumulation of sucrose in the stems and leaves of D. officinale to varying degrees， as well as the accumulation of polysaccharides， mannose， and glucose in the stems. In addition， nano-calcium carbonate treatment also facilitated the accumulation of fructose in the stems and leaves of D. officinale. Specifically， during the harvesting period in November， polysaccharides and mannose， which were the main active ingredients in D. officinale stems， increased by 28.48% and 29.36% after treatment with calcium nitrate tetrahydrate， and by 39.91% and 82.62% after treatment with nano-calcium carbonate， respectively. In addition， compared with the blank group， the concentrations of auxin in the stems and leaves of D. officinale were significantly increased after treatment with calcium nitrate tetrahydrate（P<0.05）. Similarly， the concentrations of cytokinin and auxin in the stems of D. officinale were also elevated after treatment with nano-calcium carbonate. Correlation analysis further indicated that elongation growth and tillering of D. officinale stems after foliar spraying of nano-calcium carbonate and calcium nitrate tetrahydrate might be related to the accumulation of carbohydrates in the stems and leaves and the synergistic effect of auxin and cytokinin. ConclusionIn production practice， spraying nano-calcium carbonate and calcium nitrate tetrahydrate can promote the accumulation of cytokinin， auxin， and carbohydrate contents in the stems and leaves of D. officinale， and promote tillering and elongation growth of the stems.

Objective To analyze the technical movement characteristics of female table tennis play-ers with shoulder impingement syndrome when hitting a forehand topspin loop ball,in order to explore the reasons for shoulder impingement syndrome.Methods Thirteen female table tennis athletes with shoulder impingement syndrome were recruited for the shoulder impingement group(age 20.31±2.56 years,height 165.69±4.00 cm,weight 56.62±6.00 kg)and 13 healthy female table tennis athletes(age 21.54±2.78 years,height 165.54±4.45 cm,weight 60.08±8.02 kg)were selected for the healthy group.Kinematic and electromyographic data of the upper limbs were collected during six tri-als of forehand topspin strokes using a three-dimensional motion capture system and a wireless surface electromyographic system.The data were then averaged and compared between the groups.Results The shoulder impingement group had a greater shoulder flexion angular velocity at the end of the forward swing compared to the healthy group(t=-3.689,P=0.001).In addition,the shoulder impingement group showed significantly smaller trunk torsion angular amplitude(t=2.614,P=0.015)and average an-gular velocity of trunk torsion(t=3.958,P=0.001).Furthermore,the peak activation level of the anteri-or serratus muscle was smaller in the shoulder impingement group compared to the healthy group(t=2.363,P=0.027).Finally,the deactivation duration of both the triceps brachii and brachioradialis mus-cles was shorter in the shoulder impingement group compared to the latter(t=3.705,P=0.002;t=3.29,P=0.004).Conclusion Female table tennis players with shoulder impingement syndrome exhibit the fol-lowing characteristics in their forehand topspin:1)insufficient trunk rotation and premature deactiva-tion of the brachioradialis muscle,which lead to excessive loading on the shoulder during flexion;2)inadequate activation of the serratus anterior muscle,resulting in compromised scapular stability;3)premature deactivation of the triceps brachii muscle,which negatively affects the control of eccentric contraction velocity at the shoulder joint.

Objective:To assess the impacts of abdominal spectral computed tomography (CT) scans on radiation dose in order to validate the feasibility of low-dose spectral CT imaging.Methods:Using varying scanning protocols on the Discovery CT750 HD device, the abdomen of an adult male dose-specific phantom was scanned in two modes: conventional single-energy CT (SECT) and gemstone spectral imaging (GSI). Specifically, the conventional SECT mode featured tube voltages of 120 and 80 kVp, automatic tube current modulation technology, and a noise index (NI) of 10 HU. In contrast, the GSI mode was characterized by the automatic spectral imaging protocol selection (ASIS) technique, rapid switching of the tube voltage between 80 and 140 kVp, and Nis for non-spectral scanning of 8, 10, 15, and 20 HU. Then, various radiation dose metrics and objective image quality were compared across different scanning protocols.Results:In the case of the same NI, the three scanning dose modes (SECT with tube voltages of 120 and 80 kVp, and GSI with a tube voltage of 80/140 kVp) presented similar volume CT dose index (CTDI vol) and dose length product (DLP). However, the SECT with a tube voltage of 80 kVp showed the lowest measured organ absorbed dose ( DT; 5.89 mSv). Effective dose ( E) was determined using DLP and organ DT. The result indicated that, under the three modes except for SECT with a tube voltage of 80 kVp, the E values calculated using DLP were lower than those determinized using the organ DT, with deviations ranging from 9% to 20%. The differences in image noise levels and signal-to-noise ratios (SNR) of the three scanning modes were statistically significant ( F = 65.52, 35.09, P < 0.001). Conclusions:Spectral CT using ASIS technology can achieve low-dose spectral scanning while ensuring image quality.

Objective:To analyze the epidemiological and clinical characteristics of hospitalized patients with dengue fever in Guangdong Province in 2019, so as to provide reference for clinical diagnosis and treatment of dengue fever.Methods:The general data, laboratory examination data, clinical manifestations and prognosis data of 480 inpatients with dengue fever admitted to Eight People′s Hospital Affiliated to Guangzhou Medical University between January 4 and October 31, 2019 were analyzed retrospectively. The clinical and onset characteristics of patients with dengue fever were described.Results:Among 480 dengue patients, 442(92.1%) were dengue fever, 38(7.9%) were severe dengue, and 136(28.3%) had underlying diseases. The peak age of onset was mainly in young adults aged 20 to 49 years old, accounting for 66.0%(317/480) in total. The seasonal peak was mainly in August to October. There were 399(83.1%) local cases and 61(12.7%) imported cases. The most common clinical manifestations were fever (98.1%, 471/480), chills (72.9%, 350/480), headache (58.5%, 281/480) and bone/joint/muscle pain (67.1%, 322/480), followed by digestive tract symptoms and respiratory tract symptoms. Among 446 serum samples, 358 (80.3%) were dengue virus (DENV)-1, 54 (12.1%) were DENV-2, 34 (7.6%) were DENV-3. The main laboratory tests of the patients were leucopenia (65.8%, 316/480), low hematocrit (30.2%, 145/480), thrombocytopenia (48.3%, 232/480), neutropenia (44.8%, 215/480), elevated alanine aminotransferase (ALT) (37.7%, 181/480) and aspartate aminotransferase (AST) (59.4%, 285/480). Treatment mainly adopted symptomatic support treatment and active prevention of complications. The length of stay was (5.8±3.1) days (range 1.0-38.0 days). A total of 461(96.0%) patients were cured or improved.Conclusions:In 2019, the majority of dengue fever patients in Guangdong Province are young adults aged 20 to 49 years old, and the proportion of severe patients is high, with DENV-1 infection as the main type. After symptomatic support treatment and active prevention of complications, most of the dengue fever patients have a good prognosis.

Objective:To investigate the clinical characteristics and CT imaging features of patients with different clinical types of coronavirus disease 2019 (COVID-19), so as to provide a reference for the treatment and evaluation of COVID-19.Methods:The clinical data of 278 patients with COVID-19 admitted to Guangzhou Eighth People's Hospital from January 20th to February 10th in 2020 were collected. The patients were divided into mild, ordinary, severe and critical types. The differences of clinical symptoms and signs, laboratory examination indexes and CT image features of lung in different clinical types were analyzed and compared, and the relationship between clinical and imaging features and clinical types of diseases were analyzed.Results:Among the 278 patients with COVID-19, 130 were male (46.8%) and 148 were female (53.2%), of whom 88.8% (247/278) were 20 to 69 years old. 238 (85.6%) patients combined one or more basic diseases. The source of cases was mainly imported cases ( n = 201, 72.3%), of whom 89 cases were imported from Wuhan, accounting for 44.3% of all imported cases. With the aggravation of the disease, the male composition ratio, age and the number of basic diseases of patients gradually increased, and the incidences of fever, dry cough, chilly or chills, and fatigue in severe and critical patients were significantly higher than those in the mild and ordinary ones. The white blood cell count (WBC), neutrophil counts (NEU) and proportions (NEU%) of the severe and critical patients were higher than those of the mild and ordinary patients [WBC (×10 9/L): 5.7±3.1, 6.5±2.4 vs. 5.4±1.7, 4.9±1.6; NEU (×10 9/L): 4.4±3.1, 4.9±2.5 vs. 2.8±1.2, 2.9±1.3; NEU%: 0.72±0.13, 0.73±0.14 vs. 0.51±0.12, 0.59±0.11; all P < 0.01], while the lymphocyte count (LYM) and ratio (LYM%), platelet count (PLT) were lower than those in the mild and ordinary patients [LYM (×10 9/L): 1.0±0.4, 1.2±0.8 vs. 2.1±0.9, 1.5±0.6; LYM%: 0.21±0.11, 0.20±0.12 vs. 0.40±0.11, 0.32±0.11; PLT (×10 9/L): 177.1±47.8, 157.7±51.6 vs. 215.3±59.7, 191.8±64.3; all P < 0.05]. The level of albumin (Alb) was the lowest in the critical patients and the level of total bilirubin (TBil) was the highest, which was statistically significant as compared with the mild, ordinary and severe patients [Alb (g/L): 33.0±5.8 vs. 42.8±4.4, 39.6±5.1, 34.4±4.2; TBil (μmol/L): 20.1±12.8 vs. 12.0±8.7, 10.9±6.3, 12.2±8.3; both P < 0.01]. Lactate dehydration (LDH) and cardiac troponin I (cTnI) in the severe and critical patients were significantly higher than those in the mild and ordinary patients [LDH (μmol·s -1·L -1): 5.6±2.2, 5.0±2.9 vs. 2.8±0.9, 3.3±1.2; cTnI (μg/L): 0.010 (0.006, 0.012), 0.010 (0.006, 0.012) vs. 0.005 (0.003, 0.006), 0.005 (0.001, 0.008); both P < 0.05]. C-reactive protein (CRP) level of severe patients were higher than that in the mild, ordinary and critical patients [mg/L: 43.3 (33.2, 72.1) vs. 22.1 (16.2, 25.7), 29.7 (19.8, 43.1), 25.8 (23.0, 36.7), P < 0.01]. The level of procalcitonin (PCT) in the severe and critical patients was higher than that in the mild and ordinary patients [μg/L: 0.17 (0.12, 0.26), 0.13 (0.09, 0.24) vs. 0.06 (0.05, 0.08), 0.05 (0.04, 0.09), P < 0.01]. The typical CT imaging features were as follows: the ordinary type mainly showed the single or multiple ground glass shadows on the chest image; the severe type mainly showed the multiple ground glass shadows, infiltration shadows or solid transformation shadows. Compared with the ordinary patients, the lesions increase, and the scope of the lesion expanded to show double lungs. Critical type was mainly manifested as diffuse consolidation of both lungs with multiple patchy density increase shadows, multiple leafy patchy density increase shadows were seen on each leaf, most of them were ground glass-like density, and some were shown separately lung consolidation. Conclusions:Men, advanced aged, and combining multiple underlying diseases are high-risk populations of COVID-19, and they should pay close attention to the risk of progressing to severe or critical type. CT imaging features could be used as an important supplement when diagnosing severe and critical COVID-19.

Objective:To retrospective analyze the epidemiology, clinical characteristics, treatment and prognosis in patients with coronavirus disease 2019 (COVID-19).Methods:A total of 278 patients with COVID-19 admitted to Guangzhou Eighth People′s Hospital from January 20 to February 10, 2020 were selected. The general demographic data, epidemiological data, clinical symptoms, laboratory examinations, lung CT imaging, treatment and prognosis were analyzed.Results:There were 130 male patients (46.8%) and 148 females (53.2%) with age (48.1±17.0) years and 88.8% patients between 20-69 years. Two hundred and thirty-six (84.9%) patients had comorbidities. Two hundred and eleven cases (75.9%) were common type. The in-hospital mortality was 0.4% (1/278). The majority (201, 72.3%) were imported cases mainly from Wuhan (89, 44.3%). The most common clinical manifestations were fever (70.9%) and dry cough (61.5%). In some patients, hemoglobin (10.4%), platelets (12.6%) and albumin (55.4%) were lower than the normal range. Other biochemical tests according to liver and function were normal, while lactic dehydrogenase (LDH) was elevated in 61 patients (21.9%), creatine kinase increased in 26 patients (9.4%). Prolonged activated partial thromboplastin time (APTT) was seen in 52 patients (18.7%), D-dimer higher than normal in 140 patients (50.4%), while 117 patients (42.1%) had elevated high-sensitivity C-reactive protein. Typical CT manifestations included single or multiple ground glass shadows especially in lung periphery in early disease which infiltrated and enlarged during progressive stage. Diffuse consolidation with multiple patchy density in severe/critical cases and even "white lung" presented in a few patients. Two hundred and forty-two patients (87.1%) received one or more antiviral agents, 242 (87.1%) combined with antibacterials, 191 (68.7%) with oxygen therapy. There were 198 patients (71.2%) treated with traditional Chinese medicine.Conclusions:COVID-19 could attack patients in all ages with majority of common type and low mortality rate. Clinical manifestations involve multiple organs or systems. Progression of the disease results in critical status which should be paid much attention.

ObjectiveTo investigate the prevalence of nonalcoholic fatty liver disease (NAFLD) and related abnormal indicators among taxi drivers in Shenzhen, China, and to provide a basis for scientific prevention and treatment of fatty liver disease. MethodsA total of 1752 taxi drivers who underwent physical examination in Shenzhen Longhua District People’s Hospital from May 2018 to June 2019 were selected, and related indicators were measured, including body mass index (BMI), blood pressure, fasting plasma glucose (FPG), total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and uric acid (UA). Liver ultrasound examination was also performed. The association between the prevalence rate of NAFLD and various biochemical parameters was analyzed. The t-test was used for comparison of continuous data between two groups, and the chi-square test was used for comparison of categorical data between two groups. ResultsThe prevalence rate of NAFLD among the taxi drivers was 51.66% (905/1752), and male drivers had a significantly higher prevalence rate than female drivers［57.94% (770/1329) vs 31.91% (135/423), χ2=9.209, P=0.027］. The taxi drivers with NAFLD had significantly higher abnormal rates of BMI, blood lipids, blood pressure, FPG, and UA than those without NAFLD (χ2=5.894, 7.126, 8.045, 8.909, and 10.373, P=0.047, 0.035, 0.030, 0.028, and 0.018). The taxi drivers with a BMI of ≥28 kg/m2 had a significantly higher prevalence rate of NAFLD than those with a BMI of 24.0-27.9 kg/m2 or a BMI of ＜24 kg/m2 (male: χ2=7.904 and 18.624, P=0.035 and 0.008; female: χ2=8.613 and 31.635, P=0.029 and 0.006). The taxi drivers with working years of ＞15 years had a significantly higher prevalence rate of NAFLD than those with working years of 11-15 years, 5-10 years, and ＜5 years (male: χ2=9.781, 13.546, and 18.052, P=0.024, 0.012, and 0.008; female: χ2=7.052, 9.847, and 12.157, P=0.036, 0.023, and 0.016). ConclusionThere is a high prevalence rate of NAFLD among taxi drivers in Shenzhen, and male drivers have a higher prevalence rate than female drivers. The prevalence rate of NAFLD is associated with the abnormal rates of hyperlipidemia, obesity, hyperglycemia, and hyperuricemia and the working years in driving.