Molecular Probing of the Stress Activation Volume in Vapor Phase Lubricated Friction

When two solid objects slide over each other, friction results from the interactions between the asperities of the (invariably rough) surfaces. Lubrication happens when viscous lubricants separate the two surfaces and carry the load such that solid-on-solid contacts are avoided. Yet, even small amounts of low-viscosity lubricants can still significantly lower friction through a process called boundary lubrication. Understanding the origin of the boundary lubricating effect is hampered by challenges in measuring the interfacial properties of lubricants directly between the two surfaces. Here, we use rigidochromic fluorescent probe molecules to measure precisely what happens on a molecular scale during vapor-phase boundary lubrication of a polymer bead-on-glass interface. The probe molecules have a longer fluorescence lifetime in a confined environment, which allows one to measure the area of real contact between rough surfaces and infer the shear stress at the lubricated interfaces. The latter is shown to be proportional to the inverse of the local interfacial free volume determined using the measured fluorescence lifetime. The free volume can then be used in an Eyring-type model as the stress activation volume, allowing to collapse the data of stress as a function of sliding velocity and partial pressure of the vapor phase lubricant. This shows directly that as more boundary lubricant is applied, larger clusters of lubricant molecules become involved in the shear process thereby lowering the friction.</p

Intravenous alteplase for stroke with unknown time of onset guided by advanced imaging: systematic review and meta-analysis of individual patient data

Background: Patients who have had a stroke with unknown time of onset have been previously excluded from thrombolysis. We aimed to establish whether intravenous alteplase is safe and effective in such patients when salvageable tissue has been identified with imaging biomarkers. Methods: We did a systematic review and meta-analysis of individual patient data for trials published before Sept 21, 2020. Randomised trials of intravenous alteplase versus standard of care or placebo in adults with stroke with unknown time of onset with perfusion-diffusion MRI, perfusion CT, or MRI with diffusion weighted imaging-fluid attenuated inversion recovery (DWI-FLAIR) mismatch were eligible. The primary outcome was favourable functional outcome (score of 0–1 on the modified Rankin Scale [mRS]) at 90 days indicating no disability using an unconditional mixed-effect logistic-regression model fitted to estimate the treatment effect. Secondary outcomes were mRS shift towards a better functional outcome and independent outcome (mRS 0–2) at 90 days. Safety outcomes included death, severe disability or death (mRS score 4–6), and symptomatic intracranial haemorrhage. This study is registered with PROSPERO, CRD42020166903. Findings: Of 249 identified abstracts, four trials met our eligibility criteria for inclusion: WAKE-UP, EXTEND, THAWS, and ECASS-4. The four trials provided individual patient data for 843 individuals, of whom 429 (51%) were assigned to alteplase and 414 (49%) to placebo or standard care. A favourable outcome occurred in 199 (47%) of 420 patients with alteplase and in 160 (39%) of 409 patients among controls (adjusted odds ratio [OR] 1·49 [95% CI 1·10–2·03]; p=0·011), with low heterogeneity across studies (I2=27%). Alteplase was associated with a significant shift towards better functional outcome (adjusted common OR 1·38 [95% CI 1·05–1·80]; p=0·019), and a higher odds of independent outcome (adjusted OR 1·50 [1·06–2·12]; p=0·022). In the alteplase group, 90 (21%) patients were severely disabled or died (mRS score 4–6), compared with 102 (25%) patients in the control group (adjusted OR 0·76 [0·52–1·11]; p=0·15). 27 (6%) patients died in the alteplase group and 14 (3%) patients died among controls (adjusted OR 2·06 [1·03–4·09]; p=0·040). The prevalence of symptomatic intracranial haemorrhage was higher in the alteplase group than among controls (11 [3%] vs two [&lt;1%], adjusted OR 5·58 [1·22–25·50]; p=0·024). Interpretation: In patients who have had a stroke with unknown time of onset with a DWI-FLAIR or perfusion mismatch, intravenous alteplase resulted in better functional outcome at 90 days than placebo or standard care. A net benefit was observed for all functional outcomes despite an increased risk of symptomatic intracranial haemorrhage. Although there were more deaths with alteplase than placebo, there were fewer cases of severe disability or death. Funding: None

Estimation of Pulse Wave Velocity in Main Pulmonary Artery with Phase Contrast Mri: Preliminary Investigation

Purpose: To assess the feasibility and reproducibility of a noninvasive MRI method to measure pulse wave velocity (PWV) in the main pulmonary artery (MPA). Materials and Methods: A total of 17 subjects without,, history of pulmonary diseases (38.2 +/- 18.4 years) participated in this study. Series of MR velocity maps of the MPA were acquired at 2 cm. above the pulmonary valves using a two-dimensional phase- contrast sequence. Effective temporal resolution was 11 msec after interleaving two dynamic series with different values of electrocardiograph (ECG) trigger delay. PAY was derived as the rate of MPA flow variations per unit change in MPA cross-sectional area, during early systole. Seven healthy subjects underwent three repetitive examinations to investigate intrascan and interscan reproducibility. Results : Flow vs. area was highly linear in the MPA during early systole, with Pearson's coefficients ranging from 0. 982 to 0 .999, rendering derivation of PWV with little difficulty. Average value of PWV in MPA was 1.96 +/- 0.27 m/second, in good agreement with literature values measured using invasive means. The percentage intra- and interscan differences were 5.46% and -10.86%, respectively. Conclusion : Phase-contrast MRI to noninvasively measure PWV in the MPA is feasible with good reproducibility

Simultaneous Temperature and Magnetization Transfer (Mt) Monitoring during High-Intensity Focused Ultrasound (Hifu) Treatment: Preliminary Investigation on Ex Vivo Porcine Muscle

Purpose: To measure temperature change and magnetization transfer ratio MTR) simultaneously during high-intensity focused ultrasound (HIFU) treatment. Materials and Methods: This study proposed an interleaved dual gradient-echo technique to monitor the heat and tissue damage brought to the heated tissue. The technique was applied to tissue samples to test its efficacy. Results: Ex vivo experiments on the porcine muscle demonstrated that both temperature changes and MTR exhibited high consistency in localizing the heated regions. As the heat dissipated after the treatment, the temperature of the heated regions decreased rapidly but MTR continued to be elevated. Moreover. thermal dose (TD) maps derived from the temperature curves demonstrated a sharp margin in the heated regions, but MTR maps may show a spatial gradient of tissue damage, suggesting complimentary information provided by these two measures. Conclusion: In a protocol of spot-by-spot heating over a large volume of tissue, MTR provides additional values to mark the locations of previously heated regions. By continuously recording the locations of heated spots, MTR maps could help plan the next target spots appropriately, potentially improving the efficiency of HIFU treatment and reducing undesirable damage to the normal tissue

Using Magnetic Resonance Imaging to Simultaneously onitor Temperature and Magnetization Transfer for High-Intensity Focused Ultrasound Treatment

利用磁共振影像去導引高能聚焦超音波的治療，不僅能夠增加治療時定位的準確性，更能在治療之後評估治療區域的範圍。我們的研究主要是希望能夠在超音波做治療時,同時量測溫度的變化以及磁轉移效應的改變。我們設計一個雙迴訊梯度脈衝序列，可以連續且插敘式地開關一個偏離共振頻率的脈衝,藉此得到與溫度相關的相位影像以及與組織燒灼程度有關的資訊。我們將設計的脈衝序列應用於含蛋白的假體、離體豬肉及豬肝的燒灼實驗。由所得到的結果顯示：從磁轉移比率所看到的燒灼區域大小與熱劑量所看到的區域大小很一致；即使物理性的溫度升高現象在加熱之後就逐漸消失，組織受加熱後所產生的生物性磁轉移效應改變仍會存留著。除此之外，熱劑量所看到的燒灼區域是很明確的，而磁轉移比率則可以顯示某個區域中不同程度的組織傷害。因此，當治療計畫中需要一個點接著一個點地連續治療某一個區域時，生物性磁轉移效應這項影像資訊，應該可以對於後續要治療的位置提供參考的影像。生物性磁轉移效應我們所提出的方法應該能夠改善高能聚焦超音波的治療效益，對於目標區域周圍的正常或重要的組織也能減少不必要的傷害。Abstracthe utilization of MRI for guiding high-intensity focused ultrasound (HIFU) beams not only increases the localization accuracy during HIFU procedures but also allows evaluation of HIFU-induced lesions after treatment. Our study investigated the feasibility of estimating temperature changes and magnetization transfer (MT) contrast simultaneously during HIFU heating procedures, using a dual gradient-echo technique interleaved with ON and OFF off-resonant MT pulses. Egg white phantom studies and ex vivo experiments on the porcine liver and muscle tissues demonstrated that this method exhibited high consistence with thermal dose in respect of determining lesion size. Even though physical heat elevation disperses quickly after heating procedure, the biological change in MT ratio (MTR) due to tissue damage does not diminish. Moreover, thermal dose map derived from physical temperature elevation could sharply define the lesion size, whereas MTR map showed a distribution of biological effect of cell damage. The distribution of MTR, which was invisible in thermal dose map, might be helpful for efficiently arranging the locations and sonication conditions of subsequent heating spots, particularly in a spot-by-spot treatment planning. In conclusion, the proposed method could potentially improve HIFU heating efficiency and reduce unwanted heating damage to tissues nearby the targeting area.ey words: temperature, magnetization transfer, thermal therapy, high-intensity focused ultrasound, MR guided, tissue damage.Contents試委員審定書 II文致謝 III文摘要 Vbstract VIist of Figures IXist of Tables XIhapter 1 Introduction 1.1 Thermal Therapy and MR Guided HIFU 1.1.1 Thermal Therapy 1.1.2 MR guided HIFU 1.2 Current Methods of Monitoring Heating Efficiency 2.3 Motivation 4.4 Organization 5hapter 2 Theory 6.1 Measure Temperature by MRI: Proton Resonance Frequency Shift 6.1.1 MR Phase Image and Chemical Shift due to Temperature Change 6.1.2 Measure Temperature Change by Proton Resonance Frequency Shift 11.1.3 Thermal Dose Calculation 13.2 Magnetization Transfer Effect and Magnetization Transfer Ratio 14.2.1 Magnetization Transfer (MT) effect 14.2.2 Magnetization Transfer Ratio (MTR) 17hapter 3 Simultaneous Monitoring of Temperature and Magnetization Transfer 18.1 The Designed Pulse Sequence 18.2 Validation Experiments 20.2.1 Validation of Temperature Measurements 20.2.2 Sweep Frequency 24.3 Heating Experiments Set-up 28hapter 4 Experiments 31.1 Phantom Experiments 31.1.1 Experiment Set-up 32.1.2 Results 34.1.3 Quantitative Analysis 37.2 Ex Vivo Experiments on Porcine Liver 39.2.1 Experiment Set-up 39.2.2 Results 41.2.3 Quantitative Analysis 48.3 Ex Vivo Experiments on Porcine Muscle 50.3.1 Experiment Set-up 50.3.2 Results 51.3.3 Quantitative Analysis 53.4 Two Heating Spots on Phantom 56.5 MTR Values in Phantoms With Different Concentration of Egg White 59.6 Pre-treatment Experiments: To Find Out the Position of Heating Focus 63.7 Over Heating Experiment 69hapter 5 Discussion 75.1 Comparison With Other Methods for Quantifying Tissue Damage 76.2 Comparison of Spot Size Determined by Temperature, MTR and Thermal Dose 77.3 The Characteristics of MT effect in Different Tissues 81.4 Limitations 82.4.1 Slice Number and Temporal Resolution 82.4.2 Temperature Measurement 83.4.3 MTR Measurements 84.5 Future Work 85.6 Conclusions 85eferences……..….……..……..….…..…..…..…..…..…..…...….......……….... 87ist of Figuresig. 1.1. The lattice-like treatment planning 3ig. 2.1. The definition of phase 7ig. 2.2. A schematic diagram of chemical shift effect 9ig. 2.3. The flow chart relates temperature change to proton resonant frequency shift and phase 10ig. 2.4. The illustration of two pools model and magnetization transfer effect 16ig. 3.1. The developed pulse sequence. The dual gradient-echo sequence interleaved with and without off-resonance MT pulses, respectively 19ig. 3.2. The apparatus for verifying the accuracy of temperature change measured by PFR shift method 21ig. 3.3. The phase images of a tub of hot water within 634 sec 22ig. 3.4. The maps of measured temperature decrease 23ig. 3.5. The values of temperature decrease of hot water were measured by MR PRF shift and thermal meter 23ig. 3.6. The magnitude images with different offset frequencies of RF irradiation 25ig. 3.7. The values of signal intensity and CNR as a function of offset frequency at heated-spot and non-heated area of phantom 27ig. 3.8. The schematic heating apparatus 28ig. 3.9. The experimental set-up of targeting tissue and HIFU transducer 29ig. 4.1. The schematic heating process and the time course of MR acquisition for experiment of 60% egg white phantom 33ig. 4.2. The phase images and the calculated pseudo-colored temperature change maps 35ig. 4.3. Comparison of optical picture of cut face of the heated egg white phantom, MTR map, ΔMTR map 2 min after turning off of HIFU heating pulses, and the thermal dose map 37ig. 4.4. The time course of temperature change and MTR 38ig. 4.5. The schematic heating process and the time course of MR acquisition for ex vivo experiment of porcine liver 40ig. 4.7. The phase images and the calculated pseudo-colored temperature change maps 42ig. 4.8. The magnitude images with MT pulses and without MT pulses 44ig. 4.9. The estimated MTR maps of the whole time course 45ig. 4.10 Pseudo-colored maps of temperature change, MTR, filtered ΔMTR and thermal dose (TD) maps 47ig. 4.11. The time course of temperature change and MTR 49ig. 4.12. The schematic heating process and the time course of MR acquisition or ex vivo experiment of porcine muscle 51ig. 4.13. Comparison of optical picture, MTR, ΔMTR and thermal dose maps at the end of whole heating procedure 52ig. 4.14. The time course of temperature change and MTR 55ig. 4.15. The schematic heating process and the time course of MR acquisition or two heating spots of phantom 57ig. 4.16. The results of the heating spot and the previous heated spot 58ig. 4.17. The MTR valuse of phantoms with different egg white concentration 60ig. 4.18. The schematic heating process and the time course of MR acquisition or pre-treatment experiments 65ig. 4.19. The results of pre-heat experiments 67ig. 4.20. The results of over-heating experiments 72ig. 4.21. The time course of over-heating experiment 73ig. 5.1. Compare the heated spot size of porcine liver evaluated by temperature ise and MTR to that determined by thermal dose 79 ist of Tablesable 2.1. Temperature dependence coefficient α of different materials 12able 2.2. The phase change of different temperature elevation and echo time 13able 3.1. MR parameters for validation of temperature measurement. 21able 3.2. The materials included in phantom for experiment of sweep frequency 24able 4.1. The materials included in the 60% egg white phantom 33able 4.2. The MR parameters for experiment of 60% egg white phantom 33able 4.3. The MR parameters for ex vivo experiment of porcine liver 40able 4.4. The MR parameters for ex vivo experiment of porcine muscle 51able 4.5. The MR parameters for two heating spots of phantom 57able 4.6 The values of MTRin the phantoms with different concentration of egg hite 62able 4.7. The MR parameters for pre-treatment experiments …6

Adoption of the mobile Internet: An empirical study of multimedia message service (MMS)

Multimedia message service (MMS) provides more multimedia communication with entertainment effects than current text-based short message service (SMS). While many reports indicate that the mobile Internet market will be huge, little is known about whether people will accept MMS. This study applies innovation diffusion theory to examine the factors that influence the adoption of MMS. The proposed model was empirically evaluated by using survey data collected from 207 users concerning their perceptions of MMS. The findings indicate that perceptions of use were different over innovation diffusion stages. Specifically, there was a significant difference between potential adopters and users. The results may provide further insights into MMS marketing strategies.MMS Mobile application Innovation diffusion theory Adoption

Autosegmentation of Prostate Zones and Cancer Regions from Biparametric Magnetic Resonance Images by Using Deep-Learning-Based Neural Networks

The accuracy in diagnosing prostate cancer (PCa) has increased with the development of multiparametric magnetic resonance imaging (mpMRI). Biparametric magnetic resonance imaging (bpMRI) was found to have a diagnostic accuracy comparable to mpMRI in detecting PCa. However, prostate MRI assessment relies on human experts and specialized training with considerable inter-reader variability. Deep learning may be a more robust approach for prostate MRI assessment. Here we present a method for autosegmenting the prostate zone and cancer region by using SegNet, a deep convolution neural network (DCNN) model. We used PROSTATEx dataset to train the model and combined different sequences into three channels of a single image. For each subject, all slices that contained the transition zone (TZ), peripheral zone (PZ), and PCa region were selected. The datasets were produced using different combinations of images, including T2-weighted (T2W) images, diffusion-weighted images (DWI) and apparent diffusion coefficient (ADC) images. Among these groups, the T2W + DWI + ADC images exhibited the best performance with a dice similarity coefficient of 90.45% for the TZ, 70.04% for the PZ, and 52.73% for the PCa region. Image sequence analysis with a DCNN model has the potential to assist PCa diagnosis

Tetrandrine Suppresses Human Brain Glioblastoma GBM 8401/<i>luc2</i> Cell-Xenografted Subcutaneous Tumors in Nude Mice In Vivo

Tetrandrine (TET), a bisbenzylisoquinoline (BBI) alkaloid, is isolated from the plant Stephania tetrandra S. Moore and has a wide range of biological activity, including anticancer properties in vitro and in vivo. At first, we established a luciferase-expressing stable clone that was named GBM 8401/luc2 cells. Herein, the primary results indicated that TET reduced the total cell viability and induced cell apoptosis in GBM 8401/luc2 human glioblastoma cells. However, there is no available information showing that TET suppresses glioblastoma cells in vivo. Thus, we investigated the effects and mechanisms of TET on a GBM 8401/luc2 cell-generated tumor in vivo. After the tumor volume reached 100–120 mm3 in subcutaneously xenografted nude mice, all of the mice were randomly divided into three groups: Group I was treated with phosphate-buffered solution (PBS) containing 0.1% dimethyl sulfoxide, Group II with 25 mg/kg of TET, and Group III with 50 mg/kg of TET. All mice were given the oral treatment of PBS or TET by gavage for 21 days, and the body weight and tumor volumes were recorded every 5 days. After treatment, individual tumors, kidneys, livers, and spleens were isolated from each group. The results showed that TET did not affect the body weights, but it significantly decreased the tumor volumes. The TET treatment at 50 mg/kg had a two-fold decrease in tumor volumes than that at 25 mg/kg when compared to the control. TET decreased the total photon flux, and treatment with TET at 50 mg/kg had a lower total photon flux than that at 25 mg/kg, as measured by a Xenogen IVIS imaging system. Moreover, the higher TET treatment had lower tumor volumes and weights than those of the lower dose. The apoptosis-associated protein expression in the tumor section was examined by immunohistochemical analysis, and the results showed that TET treatment reduced the levels of c-FLIP, MCL-1, and XIAP but increased the signals of cleaved-caspase-3, -8, and -9. Furthermore, the hematoxylin and eosin (H & E) staining of kidney, liver, and spleen tissues showed no significant difference between the TET-treated and control groups. Overall, these observations demonstrated that TET suppressed subcutaneous tumor growth in a nude-mice model via the induction of cell apoptosis