Spectral Analysis of Muscle Hemodynamic Responses in Post-Exercise Recovery Based on Near-Infrared Spectroscopy.

Spectral analysis of blood flow or blood volume oscillations can help to understand the regulatory mechanisms of microcirculation. This study aimed to explore the relationship between muscle hemodynamic response in the recovery period and exercise quantity. Fifteen healthy subjects were required to perform two sessions of submaximal plantarflexion exercise. The blood volume fluctuations in the gastrocnemius lateralis were recorded in three rest phases (before and after two exercise sessions) using near-infrared spectroscopy. Wavelet transform was used to analyze the total wavelet energy of the concerned frequency range (0.005-2 Hz), which were further divided into six frequency intervals corresponding to six vascular regulators. Wavelet amplitude and energy of each frequency interval were analyzed. Results showed that the total energy raised after each exercise session with a significant difference between rest phases 1 and 3. The wavelet amplitudes showed significant increases in frequency intervals I, III, IV, and V from phase 1 to 3 and in intervals III and IV from phase 2 to 3. The wavelet energy showed similar changes with the wavelet amplitude. The results demonstrate that local microvascular regulators contribute greatly to the blood volume oscillations, the activity levels of which are related to the exercise quantity.

Plantar Pressure Variability and Asymmetry in Elderly Performing 60-Minute Treadmill Brisk-Walking: Paving the Way towards Fatigue-Induced Instability Assessment Using Wearable In-Shoe Pressure Sensors.

Evaluation of potential fatigue for the elderly could minimize their risk of injury and thus encourage them to do more physical exercises. Fatigue-related gait instability was often assessed by the changes of joint kinematics, whilst planar pressure variability and asymmetry parameters may complement and provide better estimation. We hypothesized that fatigue condition (induced by the treadmill brisk-walking task) would lead to instability and could be reflected by the variability and asymmetry of plantar pressure. Fifteen elderly adults participated in the 60-min brisk walking trial on a treadmill without a pause, which could ensure that the fatigue-inducing effect is continuous and participants will not recover halfway. The plantar pressure data were extracted at baseline, the 30th minute, and the 60th minute. The median of contact time, peak pressure, and pressure-time integrals in each plantar region was calculated, in addition to their asymmetry and variability. After 60 min of brisk walking, there were significant increases in peak pressure at the medial and lateral arch regions, and central metatarsal regions, in addition to their impulses (p < 0.05). In addition, the variability of plantar pressure at the medial arch was significantly increased (p < 0.05), but their asymmetry was decreased. On the other hand, the contact time was significantly increased at all plantar regions (p < 0.05). The weakened muscle control and shock absorption upon fatigue could be the reason for the increased peak pressure, impulse, and variability, while the improved symmetry and prolonged plantar contact time could be a compensatory mechanism to restore stability. The outcome of this study can facilitate the development of gait instability or fatigue assessment using wearable in-shoe pressure sensors.

Identifying Fatigue Indicators Using Gait Variability Measures: A Longitudinal Study on Elderly Brisk Walking.

Real-time detection of fatigue in the elderly during physical exercises can help identify the stability and thus falling risks which are commonly achieved by the investigation of kinematic parameters. In this study, we aimed to identify the change in gait variability parameters from inertial measurement units (IMU) during a course of 60 min brisk walking which could lay the foundation for the development of fatigue-detecting wearable sensors. Eighteen elderly people were invited to participate in the brisk walking trials for 60 min with a single IMU attached to the posterior heel region of the dominant side. Nine sets of signals, including the accelerations, angular velocities, and rotation angles of the heel in three anatomical axes, were measured and extracted at the three walking times (baseline, 30th min, and 60th min) of the trial for analysis. Sixteen of eighteen participants reported fatigue after walking, and there were significant differences in the median acceleration (p = 0.001), variability of angular velocity (p = 0.025), and range of angle rotation (p = 0.0011), in the medial-lateral direction. In addition, there were also significant differences in the heel pronation angle (p = 0.005) and variability and energy consumption of the angles in the anterior-posterior axis (p = 0.028, p = 0.028), medial-lateral axis (p = 0.014, p = 0.014), and vertical axis (p = 0.002, p < 0.001). Our study demonstrated that a single IMU on the posterior heel of the dominant side can address the variability of kinematics parameters for elderly performing prolonged brisk walking and could serve as an indicator for walking instability, and thus fatigue.

Copper nitrate-mediated synthesis of 3-aryl isoxazolines and isoxazoles from olefinic azlactones.

A copper nitrate-mediated [2 + 2 + 1] cycloaddition reaction was developed for the expedient synthesis of pharmacologically interesting 3-aryl substituted isoxazolines and isoxazoles through C[double bond, length as m-dash]C bond cleavage. Copper nitrate is employed as a reaction promoter and precursor of nitrile oxides. The given approach features a new mode of cycloaddition from olefinic azlactones, copper nitrate and unsaturated compounds with wide substrate scope, good functional group tolerance and operational simplicity.

Isocyanide-Induced Activation of Copper Sulfate: Direct Access to Functionalized Heteroarene Sulfonic Esters.

A novel and direct approach to alkyl/aryl heteroarene sulfonic esters using copper sulfate as the environmentally benign inorganic sulfonation reagent was first realized with the aid of isocyanide. A variety of heterocycles reacted to afford the corresponding sulfonic esters through C-H functionalization. In this transformation, the otherwise inert copper sulfate was unusually activated by an isocyanide and employed as the source of the sulfonic substituents in an unprecedented fashion. The findings suggest that an appropriate activator may liberate the chemical activities of some relatively inert inorganic salts for organic synthesis.

Age-related alterations in phase synchronization of oxyhemoglobin concentration changes in prefrontal tissues as measured by near-infrared spectroscopy signals.

The prefrontal cortex plays an important role in planning complex cognitive behavior, personality expression, and decision making. This study aims to assess the phase synchronization of signals of the oxyhemoglobin concentration changes (Δ[HbO2]) in the left and right prefrontal tissues through near-infrared spectroscopy (NIRS) with wavelet phase coherence (WPCO) method. The NIRS signals were continuously recorded from the left and right prefrontal lobes in 43 healthy elderly subjects (age: 69.6 ± 8.4 years) and 40 young healthy subjects (age: 24.5 ± 1.7 years) during the resting state. Phase synchronization between the left and right prefrontal oscillations in six frequency intervals (I, 0.6-2 Hz; II, 0.145-0.6 Hz; III, 0.052-0.145 Hz; IV, 0.021-0.052 Hz; V, 0.0095-0.021 Hz; and VI, 0.005-0.0095 Hz) was analyzed using the WPCO method. The WPCO values of elderly subjects were significantly lower in frequency intervals I (F=7.376, p=0.010) and III (F=6.418, p=0.016) than those of the young subjects. Low phase coherence in intervals I and III indicates reduced synchronization of cardiac activity in the prefrontal area and weakened prefrontal functional connectivity, respectively.

Copper-catalyzed aerobic cascade cycloamination and acyloxylation: a direct approach to 4-acyloxy-1H-pyrazoles.

A novel direct transformation of hydrazones to acyloxylated pyrazoles by copper-catalyzed regioselective olefinic C(sp(2))-H bond cycloamination and acyloxylation was performed under mild conditions, which combines the formation of the pyrazole skeleton and installation of an acyloxyl group in a single step, using facile carboxylic acids as the acyloxylation reagents.

[Determination of N-isopropylaniline in workplace air by high-performance liquid chromatography].

OBJECTIVE: To establish the method of high-performance liquid chromatography (HPLC) for the determination of N-isopropylaniline in workplace air. METHODS: N-isopropylaniline in the air was collected by silicone tube, and was then dissolved by acetonitrile and determined by HPLC-UV detector. RESULTS: There was a linear relationship within the range of 0.0-100.0 µg/ml with the method, and the regression equation was y=22 863x+10 665(r=0.999 9); the detection limit was 0.005 µg/ml, and the minimum detectable concentration was 1.7x10(-3) mg/m3 (3.0 L sampling volume); the average recoveries of standard addition were 96.2%-101.3%. The within-run precision was 2.31%-2.99%, and the between-run precision was 3.21%-4.55%. The average desorption efficiency was 97.6%, the breakthrough volume was more than 8.12 mg, the sampling efficiency waE 100%, and the samples could be stored for at least 7 days at room temperature. CONCLUSION: The indicators ol the method all meet the requirements of GBZ/T 210.4-2008 (Determination methods of air chemicals in workplace), and can be used for the determination of N-isopropylaniline in workplace air.

[Gas chromatography for determination of N-butylbenzene in workplace atmosphere].

OBJECTIVE: To establish a method for the determination of N-butylbenzene in the workplace atmosphere by gas chromatography. METHODS: N-butylbenzene in the workplace atmosphere was collected by activated charcoal tube, desorbed using carbon disulfide, and determined by capillary column gas chromatography. RESULTS: The method showed a linear relationship within the range of 0∼100 µg/ml. The regression equation was y = 0.870x-0.014, with the correlation coefficient r being 0.999 9. The limit of detection was 0.32 µg/ml. The minimum detectable concentration was 0.21 mg/m³ (with sampled air volume of 1.5 L). The average spike recovery rate was 97.8%∼102.6%. The within-run precision was 3.06% and the between-run precision was 3.64%. The rate of average desorption was 99.6%. The breakthrough volume was 6.34 mg. The sampling efficiency was 100%. The samples could be stored for at least 7 days at room temperature. CONCLUSION: All parameters of the method meet the requirements of GBZ/T 210.4-2008 "Guide for establishing occupational health standards-Part 4 Determination methods of air chemicals in workplace" and can be applied for the determination of N-butylbenzene in workplace atmosphere.

Rhodium-catalyzed direct C-H bond cyanation of arenes with isocyanide.

An efficient rhodium-catalyzed regioselective C-H bond cyanation of arenes was developed using tert-butyl isocyanide as the cyanide source. A wide range of (hetero)aryl and cycloalkenyl nitriles could be afforded with high regioselectivity and good functional group tolerance.

Rhodium-catalyzed direct ortho C-N bond formation of aromatic azo compounds with azides.

An efficient rhodium-catalyzed regioselective C-N bond formation of azo compounds in good to excellent yields through C-H bond functionalization using azides as the nitrogen source was developed. Alkyl, aryl, and sulfonyl azides could be efficiently assembled in this reaction with excellent functional group tolerance.

[Determination of chloropicrin in air of workplace by gas chromatography with absorption solution collection].

OBJECTIVE: To establish a method for determination of chloropicrin in the air of workplace by gas chromatography with liquid absorption collection. METHODS: Chloropicrin in sample air was collected by absolute ethyl alcohol in a porous glass plate absorption tube. Following direct sample loading, samples were separated by gas chromatography and detected with a micro-electron capture detector. The present method was compared with the national standard method. RESULTS: The range of linearity was 0-3.0 µg/ml, and the regression equation was y = 3488.80x-57.84, with a correlation coefficient of 0.999 4. The detection limit was 0.003 µg/ml, with a minimum detectable concentration of 0.005 mg/m³ based on a 3.0 L sampling volume. The average recovery rate was 98.9%∼103.2%. The within-run precision was 0.96%-2.12%, and the between-run precision was 2.75%-4.59%. The sampling efficiency was 98.6%. Samples in porous glass plate absorption tube could be stored at 4 °C for at least 5 days. The result ratio of this method to the national standard method was 97.7%-108.0% . CONCLUSION: The present method meets the requirements of "Guide for establishing occupational health standards-Part 4: Determination methods of air chemicals in workplace" (GBZ/T 210.4-2008), and is feasible for determination of chloropicrin in the air of workplace.

Palladium-Catalyzed Asymmetric O-1,5-Addition with Oximes via Hydroximation of Unsaturated Esters.

Different from electronically matched 1,4- and 1,6-additions, herein, we disclose an electronically mismatched 1,5-conjugate addition process with oximes as the nucleophiles. By this design, the oxime moieties are readily introduced to the γ-position of the electron-deficient substrates in good yields, excellent regioselectivities, and high enantioselectivities. The corresponding allyl oximes are also conveniently transformed into a series of valuable enantioenriched skeletons.

Suitable Heel Height, a Potential Method for Musculoskeletal Problems during the Third Trimester: A Pilot Study.

BACKGROUND: The treatment options for third-trimester musculoskeletal issues are limited. This study aims to examine how heel height affects gait biomechanics and provides heel height recommendations for various musculoskeletal problems. METHODS: Five third-trimester gravidas were recruited wearing uniform footwear with four heel heights (0 mm, 15 mm, 30 mm, and 45 mm). Lower-limb muscle forces, joint angles, joint torques, joint contact forces, and ground reaction forces (GRF) at specific moments (the first peak, valley, and second peak of GRF) were collected for one-way analysis of variance with repeated measures. RESULTS: The soleus, gastrocnemius, tibialis posterior, plantaris, obturator externus, gluteus maximus, gemellus superior, and obturator internus were the smallest at heel heights of 45 mm and 15 mm at the valley of GRF. Hip extension and knee flexion displayed the smallest joint angle and joint torques at a height of 15 mm. Ankle joint contact force decreased with increased heel height. CONCLUSIONS: The height of the heel significantly impacts muscle force, joint angles, joint torques, and joint contact force. A heel of 15 mm might be the most suitable heel height to potentially avoid or alleviate musculoskeletal problems during the third trimester.

Effects of prolonged brisk walking induced lower limb muscle fatigue on the changes of gait parameters in older adults.

BACKGROUND: Lower extremity muscle fatigue affects gait stability and increases the probability of injuries in the elderly. RESEARCH QUESTION: How does prolonged walking-induced fatigue affect lower limb muscle activity, plantar pressure distribution, and tripping risk? METHODS: Eighteen elderly adults walked fast on a treadmill for 60 minutes at a fixed speed. The plantar pressure was measured with an in-shoe monitoring system, eight lower limb muscles were monitored using surface electromyography, and foot movements were tracked by a motion capture analysis system. The above data and participants' subjective fatigue level feedback were collected every 5 minutes. Statistical analysis used the Friedman one-way repeated measures analysis of variance by ranks test followed by Wilcoxon signed-ranks test with Benjamini-Hochberg stepwise correction. RESULTS: The subjective reported fatigue on the Borg scale increased gradually from 1 to 6 (p = 0.001) during the 60 minutes, while the EMG amplitude of vastus medialis significant decreased (p = 0.013). The results of plantar pressure demonstrated that the distribution of load and impulse shifted medially in both the heel and arch regions while shifted laterally in both the toes and metatarsal regions. The significantly increased contact area supports this shift at the medial arch (p = 0.036, increased by 6.94%, the 60th minute vs. the baseline). The symmetry of medial-lateral plantar force increased at the toes, metatarsal, and arch regions. The significantly increased parameters also include the swing time and contact time. The minimum foot clearance was reduced, increasing tripping probability, not significantly, though. SIGNIFICANCE: This study facilitates a better understanding of changes in lower limb muscle activity and gait parameters during prolonged fast walking. Besides, this study has good guiding significance for developing smart devices based on plantar force, inertial measurement units, and EMG sensors to monitor changes in muscle activation in real-time and prevent tripping.

[Detection of chlorpyrifos in air of workplace with HPLC].

OBJECTIVE: To establish the method of detecting the concentrations of chlorpyrifos in air of workplace with high performance liquid chromatographic (HPLC). METHODS: According to standards of methods for determining the chemical substances in workplace air, chlorpyrifos in the air was collected by silicone tube, then dissolved by acetonitrile and determined by high performance liquid chromatography with UV-detector. RESULTS: There was a linear relationship within the range of 0 ∼ 10.0 µg/ml, and regression equation was y = 5206.1x - 104.7, correlation coefficient was 0.9999, the detection limit was 0.006 µg/ml. The lowest detected concentration was 0.001 mg/m(3) (sampling volume 4.5 L). The average recoveries was 98.3% ∼ 102.5%. The within-run precision was 1.96% ∼ 4.39%, the between-run precision was 2.76% ∼ 5.87%. The desorption efficiencies were 99.0% ∼ 103.3% and the sampling efficiencies were 94%. The samples in silicone tube could be stored for 15 days at room temperature. CONCLUSION: The present method could meet with the requirements of Guide for establishing occupational health standards-Part 4 Determination methods of air chemicals in workplace and be feasible for determination of chlorpyrifos in workplace air.

Multicomponent Reaction of Isocyanide, Ditelluride, and Mn(III) Carboxylate: Synthesis of N-Acyl Tellurocarbamate.

A multicomponent reaction of isocyanides, ditellurides and manganese(III) carboxylates under mild reaction conditions leads to the synthesis of various N-acyl tellurocarbamates. This method demonstrates good functional tolerance and broad substrate scope and, as a result, is especially suitable for the postfunctionalization of complicated molecules such as drugs. The given method can be further extended to the synthesis of selenocarbamates.

Changes in segment coordination variability and the impacts of the lower limb across running mileages in half marathons: Implications for running injuries.

BACKGROUND: Segment coordination variability (CV) is a movement pattern associated with running-related injuries. It can also be adversely affected by a prolonged run. However, research on this topic is currently limited. The purpose of this study was to investigate the effects of a prolonged run on segment CV and vertical loading rates during a treadmill half marathon. METHODS: Fifteen healthy runners ran a half marathon on an instrumental treadmill in a biomechanical laboratory. Synchronized kinematic and kinetic data were collected every 2 km (from 2 km until 20 km), and the data were processed by musculoskeletal modeling. Segment CVs were computed from the angle-angle plots of selected pelvis-thigh, thigh-shank, and shank-rearfoot couplings using a modified vector coding technique. The loading rate of vertical ground reaction force was also calculated. A one-way MANOVA with repeated measures was performed on each of the outcome variables to examine the main effect of running mileage. RESULTS: Significant effects of running mileage were found on segment CVs (p ≤ 0.010) but not on loading rate (p = 0.881). Notably, during the early stance phase, the CV of pelvis frontal vs. thigh frontal was significantly increased at 20 km compared with the CV at 8 km (g = 0.59, p = 0.022). The CV of shank transverse vs. rearfoot frontal decreased from 2 km to 8 km (g = 0.30, p = 0.020) but then significantly increased at both 18 km (g = 0.05, p < 0.001) and 20 km (g = 0.36, p < 0.001). CONCLUSION: At the early stance, runners maintained stable CVs on the sagittal plane, which could explain the unchanged loading rate throughout the half marathon. However, increased CVs on the frontal/transverse plane may be an early sign of fatigue and indicative of possible injury risk. Further studies are necessary for conclusive statements in this regard.

Different Design Feature Combinations of Flatfoot Orthosis on Plantar Fascia Strain and Plantar Pressure: A Muscle-Driven Finite Element Analysis With Taguchi Method.

Customized foot orthosis is commonly used to modify foot posture and relieve foot pain for adult acquired flexible flatfoot. However, systematic investigation of the influence of foot orthotic design parameter combination on the internal foot mechanics remains scarce. This study aimed to investigate the biomechanical effects of different combinations of foot orthoses design features through a muscle-driven flatfoot finite element model. A flatfoot-orthosis finite element model was constructed by considering the three-dimensional geometry of plantar fascia. The plantar fascia model accounted for the interaction with the bulk soft tissue. The Taguchi approach was adopted to analyze the significance of four design factors combination (arch support height, medial posting inclination, heel cup height, and material stiffness). Predicted plantar pressure and plantar fascia strains in different design combinations at the midstance instant were reported. The results indicated that the foot orthosis with higher arch support (45.7%) and medial inclination angle (25.5%) effectively reduced peak plantar pressure. For the proximal plantar fascia strain, arch support (41.8%) and material stiffness (37%) were strong influencing factors. Specifically, higher arch support and softer material decreased the peak plantar fascia strain. The plantar pressure and plantar fascia loading were sensitive to the arch support feature. The proposed statistics-based finite element flatfoot model could assist the insole optimization and evaluation for individuals with flatfoot.