Impacts of ship emissions and sea-land breeze on urban air quality using chemical characterization, source contribution and dispersion model simulation of PM2.5 at Asian seaport.

Fine particulate matter (PM2.5) emitted from marine transportation, bulk materials handling at the docks, and dust dispersion has garnered increased attention, particularly in the interface between port and urban areas. This study explored the inter-transport of PM2.5 between Kaohsiung Harbor and neighboring Metro Kaohsiung. Chemical analyses of PM2.5 samples from four sites include water-soluble ions, metallic elements, carbons, anhydrosugars, and organic acids to establish PM2.5's chemical fingerprints. The CALPUFF air dispersion model is employed to simulate the spatiotemporal distribution of PM2.5 in Kaohsiung Harbor and adjacent urban areas. A clear seasonal and diurnal variation of PM2.5 concentrations and chemical composition was observed in both harbor and urban areas. The high correlation of nighttime PM2.5 levels between the port and urban areas suggests inter-transport phenomena. Sea salt spray, ship emissions, secondary aerosols, and heavy fuel-oil boilers exhibit higher levels in the port area than in the urban area. In Metro Kaohsiung, mobile sources, fugitive dust, and waste incinerators emerge as major PM2.5 contributors. Furthermore, sea breeze significantly influences PM2.5 dispersion from Kaohsiung Harbor to Metro Kaohsiung, particularly in the afternoon. The average contribution of PM2.5 from ships' main engines in Kaohsiung Harbor ranges from 2.9% to 5.3%, while auxiliary engines contribute 3.8%-8.3% of PM2.5 in Metro Kaohsiung.

Skill level and forearm muscle fatigue effects on ball speed in tennis serve.

This study determined the effect of skill level (ITN 3 vs. ITN 8) on the tennis serve biomechanics and analysed the impact of forearm fatigue on dominant arm mechanisms between the two groups (expert vs. non-expert tennis players). The motion capture system with 17 reflective markers attached on anatomic landmarks of the participant was used for data collection. A total of 12 expert and 11 non-expert tennis players performed the required serving tasks. The ball speed of the expert group was significantly faster than that of the non-expert group during non-fatigued and fatigued states (p < 0.001). The wrist radial/ulnar deviation angle at impact was significantly different between non-fatigued and fatigued states for top-spin (p = 0.030) and flat serves (p = 0.018). A significant increase in extensor carpi ulnaris (ECU) and extensor carpi radialis (ECR) muscle activity during extension (p < 0.010) was observed, with that of the ECU being an ulnar deviation. Both the ECU and ECR might contribute to wrist joint and racket handle stability for the coming acceleration and impact while fatigue occurs. Fatigue might substantially influence non-experts' dominant forearms because of the significantly different elbow joint angles and dominant arm syndromes they displayed as compared with the experts.

Forearm muscle activation, ulnar nerve at the elbow and forearm fatigue in overhand sports.

This study examined the morphologic changes of the ulnar nerve in different elbow positions by ultrasonography and the effects of fatigue on forearm muscle control during overhand movements. We enrolled 12 tennis players who performed flat serves and 15 baseball pitchers who performed fastball pitching. The motion capture was conducted with 14 reflective markers attached on anatomic landmarks of the participant for tennis serve and baseball pitching data collection. The distance from the nerve to the medial condyle between the tennis players and baseball pitchers showed significant differences (p = 0.006) as the elbow flexed to 90°. The differences are due to the baseball player's repetitive pitching motion while such motion does not apply to tennis player. Activity of the extensor carpi radialis (ECR) during the cocking phase in the tennis serves showed significant differences (p = 0.022) between the nonfatigued and fatigued states; the maximal value was observed in the fatigued state. The significant increase in the ECR activity in the fatigued state might be responsible for grasp-and-release activities and maintaining the wrist joint stability when performing overhand movements. Forearm fatigue influenced their overhand motion ability in accurate ball control, although it did not decrease the ball speed.

Chemical fingerprint and source apportionment of PM2.5 in highly polluted events of southern Taiwan.

To investigate the spatial distribution and diurnal variation of the chemical composition of PM2.5 pollution in an industrial city of southern Taiwan, 12-h PM2.5 was diurnally continuously collected simultaneously at the Kaoping Air Quality Zone (KAQZ) during one highly PM2.5-polluted episode. Water-soluble ions, metallic elements, carbonaceous contents, dicarboxylic acids, and anhydrosugars were analyzed to characterize the chemical fingerprint of PM2.5. Backward trajectory simulation and chemical mass balance (CMB) receptor modeling were applied to identify the potential sources of PM2.5 and their contributions. It showed that Chaozhou (rural area) accompanying the highest SORs and NORs suffered from the most severe PM2.5 pollution during the episode. Sulfate (SO42-) was probably formed by the atmospheric chemical reaction in the daytime, while NO3- processed at nighttime at the KAQZ. A homogeneous formation of NO3- occurred at Chaozhou. The concentrations of Zn, Pb, Fe, Cu, V, and Al, mainly emitted from anthropogenic sources, increased significantly at the KAQZ. The highest OC, SOC/OC, and DA/OCs at Daliao (industrial area) were attributed to the transformation of primary VOCs to secondary OC via photo-oxidation during the episode. Oxalic acid was mainly produced through photochemical reactions since a high correlation between oxalic acid and Ca2+ was observed at Nanzi (urban area) and Daliao during the episode. During the episode, PM2.5 mostly originated from local primary or secondary aerosol than long-range overseas transport. The dominant source was anthropogenic emissions, accounting for 67.1% and 70.4% of PM2.5 at Nanzi and Daliao, respectively. At Chaozhou, the contribution of anthropogenic emissions was the lowest (42.4%), but secondary aerosols had the highest contribution of 38.3% of PM2.5 among the three areas during the episode.

Vertical stratification of volatile organic compounds and their photochemical product formation potential in an industrial urban area.

High emissions of volatile organic compounds (VOCs) from the petrochemical industry and vehicle exhaust may contribute to high ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP). In this study, the vertical profiles of VOCs were created for the southern Taiwan industrial city of Kaohsiung. Vertical air samples were collected up to 1000 m using an unmanned aerial vehicle (UAV). In Renwu District, VOC distribution was affected by the inversion layer up to 200 m height. Total VOCs (36-327 ppbv), OFP (66-831 ppbv) and SOAFP (0.12-5.55 ppbv) stratified by height were the highest values at 300 m. The VOCs originated from both local and long-distance transport sources. These findings can be integrated into Kaohsiung's future air quality improvement plans and serve as a reference for other industrialized areas worldwide.

Comparison of Ball-And-Racket Impact Force in Two-Handed Backhand Stroke Stances for Different-Skill-Level Tennis Players.

This study compared the kinetic roles of the upper extremities in racket impact force generation between the open stance (OS) and square stance (SS) for tennis players with different skill levels in two-handed backhand strokes. Twelve male tennis players were divided into an advanced group (AG) (L3-L2 skill level) and intermediate group (IG) (L7-L6 skill level), and their data were used in a three-dimensional kinetic analysis. Their motions were captured using 21 reflective markers attached to anatomic landmarks for two-handed backhand stroke motion data collection. During the acceleration phase, significant differences were not observed between both stances, but they were observed between the groups with different skill levels for the force of the upper extremities (p = 0.027). The joint forces were significantly lower in the AG than in the IG. Players performing the SS had significantly larger pronation and supination of the wrist joint moment than those in the OS (p = 0.032) during the acceleration phase, irrespective of the playing level. Higher internal rotation moment after impact was observed at each joint, particularly among young intermediate tennis players, regardless of their stance. The AG demonstrated a higher joint force and moment at every joint compared with the IG at impact. Moreover, the AG demonstrated superior stroke efficiency and effectively reduced joint moment after impact and sports injury. Key pointsAdvanced players, regardless of open stance or square stance, have larger joint force and moment at each joint before ball impact resulting in better stroke efficiency and reduced chance of injury.Intermediate players, regardless of stance, have higher internal rotation moment at each joint instead of larger joint force as compared to advanced players before ball impact. The higher internal rotation moment will induce higher joint impact force which makes the player injury-prone.Young intermediate tennis players may want to avoid excessive follow-through movement after ball impact to prevent injury in their early career.

The effects of forearm fatigue on baseball fastball pitching, with implications about elbow injury.

This study investigated the contribution of flexor muscles to the forearm through fatigue; therefore, the differences in forearm mechanisms on the pitching motion in fastball were analysed. Fifteen baseball pitchers were included in this study. Ultrasonographical examination of participants' ulnar nerve in the cubital tunnel with the elbow extended and at 45°, 90° and 120° of flexion was carried. A three-dimensional motion analysis system with 14 reflective markers attached on participants was used for motion data collection. The electromyography system was applied over the flexor carpi ulnaris, flexor carpi radialis and extensor carpi radialis muscles of the dominant arm. Flexor carpi ulnaris muscle activity showed a significant difference during the acceleration phase, with a peak value during fastball post-fatigue (P = 0.02). Significant differences in the distance between ulnar nerve and medial condyle on throwing arm and non-throwing arm were observed as the distance increased with the elbow movement from 0° to 120° of flexion (P = 0.01). The significant increase of the flexor carpi ulnaris muscle activity might be responsible for maintaining the stability of the wrist joint. The increased diameter might compress the ulnar nerve and cause several pathological changes. Therefore, fatigue in baseball pitchers still poses a threat to the ulnar nerve because the flexor carpi ulnaris and flexor carpi radialis all originate from the medial side of the elbow, and the swelling tendons after fatigue might be a key point.

Lower Extremity Muscle Activation and Kinematics of Catchers When Throwing Using Various Squatting and Throwing Postures.

This study investigated the differences in joint motions and muscle activities of the lower extremities involved in various squatting postures. The motion capture system with thirty-one reflective markers attached on participants was used for motion data collection. The electromyography system was applied over the quadriceps, biceps femoris, tibialis anterior, and gastrocnemius muscles of the pivot and stride leg. The joint extension and flexion in wide squatting are greater than in general squatting (p = 0.005). Knee joint extension and flexion in general squatting are significantly greater than in wide squatting (p = 0.001). The adduction and abduction of the hip joint in stride passing are significantly greater than in step squatting (p = 0.000). Furthermore, the adduction and abduction of the knee joint in stride passing are also significantly greater than in step squatting (p = 0.000). When stride passing is performed, the muscle activation of the hamstring of the pivot foot in general squatting is significantly greater than in wide squatting (p < 0.05), and this difference continues to the stride period. Most catchers use a general or wide squatting width, exclusive of a narrow one. Therefore, the training design for strengthening the lower extremity muscles should consider the appropriateness of the common squat width to enhance squat-up performance. For lower limb muscle activation, wide squatting requires more active gastrocnemius and tibialis anterior muscles. Baseball players should extend the knee angle of the pivot foot before catching the ball. Key pointsCommon squatting width can enhance squat-up performance through strengthening lower body muscle.Wide squatting width might improve lower body muscle activation, leading to more effective communication between the brain and the muscle group. The benefit might be improved coordination of lower body muscle.Common and wide squatting width might be cycled through training to enhance the strengthen and coordination of the lower body muscle, respectively.

Comparison of dominant hand range of motion among throwing types in baseball pitchers.

Previous research on baseball pitchers' wrists, elbows, and should joints contributes to our understanding of pitchers' control over delicate joint motion and ball release. However, limited research on forearm, wrist, and hand joints prevents full comprehension of the throwing mechanism. The present descriptive laboratory study quantifies angular performances of hand and wrist joints while pitching breaking balls, including fastballs, curveballs and sliders, among pitchers with different skill levels. Nineteen baseball pitchers performed required pitching tasks (10 from university and 9 from high school). A three-dimensional motion analysis system collected pitching motion data. The range of joint motion in the wrist and proximal interphalangeal (PIP) and metacarpophalangeal (MP) joints of the index and middle fingers were compared among fastballs, curveballs and sliders. Thirteen reflective markers were placed on selected anatomic landmarks of the wrist, middle and index fingers of the hand. Wrist flexion angle in the pitching acceleration phase was larger in fastballs (20.58±4.07°) and sliders (22.48±5.45°) than in curveballs (9.08±3.03°) (p = .001). The flexion angle of the PIP joint was significantly larger in curveballs (38.5±3.8°) than in fastballs (30.3±4.8°) and sliders (30.2±4.5°) (p=.004) of the middle finger. Abduction angle of MP joint on the middle finger was significantly larger in curveballs (15.4 ±3.6°) than in fastballs (8.9±1.2°) and sliders (6.9±2.9°) (p=.001) of the middle finger, and the abduction angle of index finger was significantly larger in sliders (13.5±15.0°) than in fastballs (7.2 ±2.8°) (p=.007). Hand and wrist motion and grip types affect the relative position between fingers and ball, which produces different types of baseball pitches. A larger extension angle of the wrist joint and the coordination of middle and index fingers are crucial when pitching a fastball. Abduction and flexion movement on the MP joint of the middle finger are important for a curveball. MP joint abduction and flexion movement of the index finger produce sliders. Understanding the control mechanism in a throwing hand can help improve training protocols in either injury prevention or performance improvement for baseball pitchers.

Comparison of segmental linear and angular momentum transfers in two-handed backhand stroke stances for different skill level tennis players.

The purpose of this study was to investigate the differences of momentum transfer from the trunk and upper extremities to the racket between open and square stances for different skill levels players in the two-handed backhand stroke. The motion capture system with twenty-one reflective markers attached on anatomic landmarks of the subject was used for two-handed backhand stroke motion data collection. Twelve subjects were divided into an advanced group and an intermediate group based on skill level. The three-dimensional linear and angular momentums of the trunk, upper arm, forearm, hand and racket were used for kinetic chain analysis. Results showed that all players with the square stance had significantly larger backward linear momentum contribution in trunk and upper arm than with the open stance (p<.05) irrespective of playing level. However, the external rotation angular momentum of the shoulder joint was significantly larger with an open stance than with a square stance (p=.047). Comparison of playing levels showed that the intermediate group performed higher linear momentum in three components of the trunk, upper arm backward linear momentum, and trunk right bending angular momentum than the advanced group significantly (p<.05). The advanced group reduces trunk linear movement to keep stability and applies trunk and linkage segment rotation to generate backhand stroke power. The advanced group also has a quick backswing for increasing acceleration and maintains longer in the follow-through phase for shock energy absorption. This information could improve training protocol design for teaching the two-handed backhand stroke and teaching players, especially beginners, how to make an effective stroke.