Optimization of Sacrificial Layer Etching in Single-Crystal Silicon Nano-Films Transfer Printing for Heterogeneous Integration Application.

As one of the important technologies in the field of heterogeneous integration, transfer technology has broad application prospects and unique technical advantages. This transfer technology includes the wet chemical etching of a sacrificial layer, such that silicon nano-film devices are released from the donor substrate and can be transferred. However, in the process of wet etching the SiO2 sacrificial layer present underneath the single-crystal silicon nano-film by using the transfer technology, the etching is often incomplete, which seriously affects the efficiency and quality of the transfer and makes the device preparation impossible. This article analyzes the principle of incomplete etching, and compares the four factors that affect the etching process, including the size of Si nano-film on top of the sacrificial layer, the location of the anchor point, the shape of Si nano-film on top of the sacrificial layer, and the thickness of the sacrificial layer. Finally, the etching conditions are obtained to avoid the phenomenon of incomplete etching of the sacrificial layer, so that the transfer technology can be better applied in the field of heterogeneous integration. Additionally, Si MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) on sapphire substrate were fabricated by using the optimized transfer technology.

Simultaneous measurement of salinity and temperature using a Sagnac interferometer based on concatenated polarization-maintaining fiber tapers.

A Sagnac loop interferometer based on concatenated polarization-maintaining fiber (PMF) tapers is proposed for simultaneous measurement of seawater salinity and temperature. The influences of the distance between the PMF tapers as well as fiber taper diameter on sensor performance have been investigated. Experimental results indicate that the fabricated sensor with a distance of 3 cm between adjacent fiber tapers possesses the salinity and temperature sensitivities of 0.367 nm/% and -0.728nm/∘C, respectively, and the taper waist diameter of 20 µm would help to improve salinity sensitivity in comparison with a sensor of 30 µm in diameter. The proposed Sagnac loop interferometer based on concatenated PMF tapers is expected to find potential applications in the measurement of seawater salinity.

Ultrafast Resolution-Enhanced Digital Optical Frequency Comb-Based BOTDA with Pump Pulse Array Coding.

In this letter, a resolution enhancement and signal-to-noise ratio (SNR) improvement scheme for digital optical frequency comb (DOFC)-based Brillouin optical time-domain analysis (BOTDA) ultrafast distributed sensing employing a pump pulse array is proposed. Based on the properties of the time-invariant linear system and the cyclic revolution theorem, experimental results indicate that its spatial resolution reaches 10.24 m while the frequency uncertainty is below 2 MHz over a 9.5 km fiber. Moreover, the response time is only 209.6 µs and the temperature measurement error is less than 0.52 °C.

High-performance Acetone Soluble Tape Transfer Printing Method for Heterogeneous Integration.

A high-performance transfer printing method using a new soluble tape which can be dissolved in acetone is proposed to be used in heterogeneous integration. Si inks array was transferred from SOI wafers onto various substrates without adhesion promoter by this new method which we refer to as the acetone soluble tape (AST) method to compare with other transfer printing methods by using thermal release tape (TRT), water soluble tape (WST) and polydimethylsiloxane (PDMS). By using the AST method, the transfer printing process does not involve interface contention between stamp/inks and inks/receiver substrate so that it maximizes the transfer printing efficiency. Experimental results present the AST method has good performances, and various alien substrates, even curvilinear surfaces, can be selected as receiver substrates by the AST method. To examine the quality of the transferred Si inks, the Si TFTs were fabricated by using the Si membrane transferred by the AST method on sapphire substrate and the devices show the good performance. All the results confirm that the AST method is an effective method in heterogeneous integration.

Epithelial-mesenchymal transition softens head and neck cancer cells to facilitate migration in 3D environments.

The biological impact and signalling of epithelial-mesenchymal transition (EMT) during cancer metastasis has been established. However, the changes in biophysical properties of cancer cells undergoing EMT remain elusive. Here, we measured, via video particle tracking microrheology, the intracellular stiffness of head and neck cancer cell lines with distinct EMT phenotypes. We also examined cells migration and invasiveness in different extracellular matrix architectures and EMT-related signalling in these cell lines. Our results show that when cells were cultivated in three-dimensional (3D) environments, the differences in cell morphology, migration speed, invasion capability and intracellular stiffness were more pronounced among different head and neck cancer cell lines with distinct EMT phenotypes than those cultivated in traditional plastic dishes and/or seated on top of a thick layer of collagen. An inverse correlation between intracellular stiffness and invasiveness in 3D culture was revealed. Knock-down of the EMT regulator Twist1 or Snail or inhibition of Rac1 which is a downstream GTPase of Twist1 increased intracellular stiffness. These results indicate that the EMT regulators, Twist1 and Snail and the mediated signals play a critical role in reducing intracellular stiffness and enhancing cell migration in EMT to promote cancer cells invasion.

Prevalence and Trends of Cigarette Smoking Among Military Personnel in Taiwan: Results of 10-Year Anti-Smoking Health Promotion Programs in Military.

OBJECTIVES: The purpose of this study is to evaluate the prevalence and trends of cigarette smoking among young military conscripts, military officers, and military university students during recently 10 years in Taiwan. METHODS: Repeated cross-sectional surveys were conducted annually among young military conscripts and military university students from 2006 to 2014. All the young conscripts were reviewed within 1 month at the military training center and before retiring after 1 year of military services. The military officers were included using purposive sampling from 2004 to 2008 and 2013 to 2014 in different military services. Military university students were included in this study. Freshman and senior students were random sampled as the study subjects. Participants completed a structured questionnaire that included questions on general demographics and health-related behaviors. Current smokers is defined as subjects who smoked ≥1 cigarette/day during the past 30 days or had smoked ≥100 cigarettes in their lifetime or still have the habit of smoking during study. We used a χ2 test to examine the difference between the prevalence of cigarette smoking among different groups. The Cochran-Armitage test for trend was applied to examine the change of prevalence of smoking after repeated cross-sectional surveys among populations. RESULTS: The prevalence of cigarette smoking within military training center and after 1-year military services was 48.6% and 48.1% on 2006, which became 39.2% and 38.6% on 2010, and then further declined to 31.0% and 30.1% on 2014. For military officers, the trends of prevalence of smoking among different military services showed slight decline from 2004 to 2008, but decreased significantly between 2013 and 2014. The prevalence of smoking in 2014 was 32.1%, 32.8%, and 32.4% for the Army, Navy, and Air Force, respectively. More interestingly, the prevalence of smoking of freshman and senior students increased during the first 5 years (2007-2011) of survey and then decreased after 2012. Furthermore, in 2014, the prevalence of smoking decreased as the difference became smaller, 4.5% and 6.1% for freshman and senior, respectively. CONCLUSION: During this 10-year period, the smoking cessation programs include in-class education course, out-door physical training, antismoking clinic, and group therapy. After these military health promoting programs, there are some beneficial effects to decline the prevalence of cigarette smoking for military personnel in Taiwan. However, more active intervention and health promoting programs in prevention and cessation of smoking are needed for the military. The military also have to develop specific approaches and programs to prevent cigarette smoking among conscripts and officers.

Bio- chemical and physical characterizations of mesenchymal stromal cells along the time course of directed differentiation.

Cellular biophysical properties are novel biomarkers of cell phenotypes which may reflect the status of differentiating stem cells. Accurate characterizations of cellular biophysical properties, in conjunction with the corresponding biochemical properties could help to distinguish stem cells from primary cells, cancer cells, and differentiated cells. However, the correlated evolution of these properties in the course of directed stem cells differentiation has not been well characterized. In this study, we applied video particle tracking microrheology (VPTM) to measure intracellular viscoelasticity of differentiating human mesenchymal stromal/stem cells (hMSCs). Our results showed that osteogenesis not only increased both elastic and viscous moduli, but also converted the intracellular viscoelasticity of differentiating hMSCs from viscous-like to elastic-like. In contrast, adipogenesis decreased both elastic and viscous moduli while hMSCs remained viscous-like during the differentiation. In conjunction with bio- chemical and physical parameters, such as gene expression profiles, cell morphology, and cytoskeleton arrangement, we demonstrated that VPTM is a unique approach to quantify, with high data throughput, the maturation level of differentiating hMSCs and to anticipate their fate decisions. This approach is well suited for time-lapsed study of the mechanobiology of differentiating stem cells especially in three dimensional physico-chemical biomimetic environments including porous scaffolds.

Latent variable modeling and its implications for institutional review board review: variables that delay the reviewing process.

BACKGROUND: To investigate the factors related to approval after review by an Institutional Review Board (IRB), the structure equation model was used to analyze the latent variables 'investigators', 'vulnerability' and 'review process' for 221 proposals submitted to our IRB. METHODS: The vulnerability factor included vulnerable cases, and studies that involved drug tests and genetic analyses. The principal investigator (PI) factor included the license level of the PI and whether they belonged to our institution. The review factor included administration time, total review time, and revision frequency. The revision frequency and total review time influenced the efficiency of review. RESULTS: The latent variable of reviewing was the most important factor mediating the PIs and vulnerability to IRB review approval. The local PIs moderated with genetic study and revision frequency had an impact on the review process and mediated non-approval. CONCLUSIONS: Better guidance of the investigators and reviewers might improve the efficiency with which IRBs function.

Effects of horizontal acceleration on human visual acuity and stereopsis.

The effect of horizontal acceleration on human visual acuity and stereopsis is demonstrated in this study. Twenty participants (mean age 22.6 years) were enrolled in the experiment. Acceleration from two different directions was performed at the Taiwan High-Speed Rail Laboratory. Gx and Gy (< and >0.1 g) were produced on an accelerating platform where the subjects stood. The visual acuity and stereopsis of the right eye were measured before and during the acceleration. Acceleration <0.1 g in the X- or Y-axis did not affect dynamic vision and stereopsis. Vision decreased (mean from 0.02 logMAR to 0.25 logMAR) and stereopsis declined significantly (mean from 40 s to 60.2 s of arc) when Gx > 0.1 g. Visual acuity worsened (mean from 0.02 logMAR to 0.19 logMAR) and poor stereopsis was noted (mean from 40 s to 50.2 s of arc) when Gy > 0.1 g. The effect of acceleration from the X-axis on the visual system was higher than that from the Y-axis. During acceleration, most subjects complained of ocular strain when reading. To our knowledge, this study is the first to report the exact levels of visual function loss during Gx and Gy.

SPAK deficiency corrects pseudohypoaldosteronism II caused by WNK4 mutation.

Stimulation of the OSR1 (Oxidative stress-responsive kinase-1)/SPAK [STE20 (sterile 20)/SPS1-related proline/alanine-rich kinase]-NCC (Na(+)-Cl(-) cotransporter) signaling cascade plays an important role in the WNK [With-No-Lysine (K)] kinase 4 D561A knock-in mouse model of pseudohypoaldosteronism type II (PHA II) characterized by salt-sensitive hypertension and hyperkalemia. The aim of this study was to investigate the respective roles of Osr1 and Spak in the pathogenesis of PHA II in vivo. Wnk4 (D561A/+) mice were crossed with kidney tubule-specific (KSP) Osr1 knockout (KSP-Osr1 (-/-)) and Spak knockout (Spak (-/-)) mice. Blood pressure, plasma and urine biochemistries, and the relevant protein expression in the kidneys were examined. Wnk4 (D561A/+), KSP-Osr1 (-/-), and Spak (-/-) mice recapitulated the phenotypes of PHA II, Bartter-like syndrome, and Gitelman syndrome, respectively. Wnk4 (D561A/+).KSP-Osr1 (-/-) remained phenotypically PHA II while Wnk4 (D561A/+).Spak (-/-) mice became normotensive and lacked the PHA II phenotype. Phosphorylated Spak and Ncc were similarly increased in both Wnk4 (D561A/+) and Wnk4 (D561A/+).KSP-Osr1 (-/-) mice while phosphorylated Ncc normalized in Wnk4 (D561A/+).Spak (-/-) mice. Furthermore, Wnk4 (D561A/+).KSP-Osr1 (-/-) mice exhibited exaggerated salt excretion in response to thiazide diuretics while Wnk4 (D561A/+).Spak (-/-) mice exhibited normal responses. Wnk4(D561A/+).Spak (-/-).KSP-Osr1 (-/-) triple mutant mice had low blood pressure and diminished phosphorylated Ncc. Both SPAK and OSR1 are important in the maintenance of blood pressure but activation of SPAK-NCC plays the dominant role in PHA II. SPAK may be a therapeutic target for disorders with salt-sensitive hypertension related to WNK4 activation.

Vestibular paroxysmia associated with paroxysmal pulsatile tinnitus: a case report and review of the literature.

PURPOSE: Vestibular paroxysmia is defined as paroxysmal, brief, and carbamazepine-responsive vertigo. Although neurovascular cross-compression (NVCC) of the vestibulocochlear nerve is believed to be the cause of vestibular paroxysmia, the mechanism remains controversial. Herein, we describe the case of a man with NVCC who presented with paroxysmal vertigo associated with paroxysmal pulsatile tinnitus. CASE REPORT: A 68-year-old man presented with paroxysmal vertigo for one month. Paroxysmal pulsatile tinnitus in the right ear occurred simultaneously with the vertigo. Magnetic resonance imaging demonstrated that the right anterior inferior cerebellar artery was compressing the right vestibulocochlear nerve. The vertigo and tinnitus completely disappeared within one week after treatment with carbamazepine. CONCLUSION: The pulsatile nature of the patient's tinnitus implied that the auditory nerve was being compressed by a pulsating artery and was found to consolidate the causal relationship between NVCC and vestibular paroxysmia.

A tiny infarct on the dorsolateral pons mimicking vestibular neuritis.

We report a case of a tiny infarct on the left dorsolateral pons in a 50-year-old man who presented with prolonged and isolated vertigo. The clinical features mimic vestibular neuritis and can easily lead to misdiagnosis. Selective involvement of the left superior vestibular nucleus might explain the resemblance to acute peripheral vestibulopathy.

Immune reconstitution associated hypercalcemia.

The emergence of highly active antiretroviral therapy using combinations of reverse transcriptase and protease inhibitors ushered the dawn of a new era in management of human immunodeficiency virus infection. Immune reconstitution inflammatory syndrome is an adverse consequence of the restoration of pathogen-specific immune responses during the early phase of antiretroviral therapy. Pre-existing subclinical or opportunistic infections become apparent or even "worse" as host immunological inflammatory responses are "switched on". Major reductions in plasma viral load were associated with substantial increases in circulating CD4 T-cell lymphocyte counts and restoration of immune function. The rapid reversal in immune function gives rise to paradoxical therapeutic reaction by rebuilding host immune responses. Herein, a hidden culprit responsible for tuberculosis-associated immune reconstitution characterized by severe hypercalcemia and acute renal failure is reported, illustrating the compounded therapeutic strategy in AIDS patients.

Ocular responses and visual performance after high-acceleration force exposure.

PURPOSE: To evaluate ocular responses and visual performance after high-acceleration force exposure. METHODS: Fourteen men were enrolled in the study. A human centrifuge was used to induce nine times the acceleration force in the head-to-toe (z-axis) direction (+9 Gz force). Visual performance was evaluated using the ETDRS (Early Treatment of Diabetic Retinopathy Study) visual chart, and contrast sensitivity (CS) was examined before and after centrifugation. Ocular responses were assessed with biomicroscopy and topographic mapping after gravitational stress. RESULTS: Transient visual acuity reduction (0.02 +/- 0.04 logMar vs. 0.19 +/- 0.07 logMar VA; P < 0.05) and temporary ocular anterior segment reactions were observed immediately after centrifugation. These reactions included changes in corneal thickening (553.7 +/- 21.7 mum vs. 591.2 +/- 20.6 mum; P < 0.05), increasing anterior chamber depth (ACD; 3.19 +/- 0.26 mm vs. 4.53 +/- 0.34 mm; P < 0.05), and pupillary enlargement (3.54 +/- 0.73 mm vs. 5.76 +/- 0.61 mm; P < 0.05). The increase in ACD continued for 15 minutes after exposure to acceleration (3.19 +/- 0.26 mm vs. 4.39 +/- 0.27 mm; P < 0.05). Pupillary dilation was noted both 15 (3.54 +/- 0.73 mm vs. 5.56 +/- 0.67 mm; P < 0.05) and 30 (5.47 +/- 0.59 mm, P < 0.05) minutes after the gravitational stress. CS decreased significantly at low and medium spatial frequencies (1.5, 3, and 6 cyc/deg) and did not return to the baseline level by 30 minutes. CONCLUSIONS: High-acceleration force may induce transient visual acuity reduction and temporary corneal thickening. Prolonged increase in ACD and pupillary dilation were also observed. The decrease in CS persisted for 30 minutes after centrifugation. The mechanisms underlying these observations are not clear, because there are no previous reports on this topic. Further studies are needed.

Changes in visual function during the Coriolis illusion.

BACKGROUND: The Coriolis illusion produces spatial disorientation and is, therefore, dangerous for pilots. It is not known whether it also affects visual function (visual acuity and stereopsis). METHODS: There were 18 subjects (15 men and 3 women, mean age 24.7 yr) enrolled in the study. A spatial disorientation simulator was used to produce Coriolis stimulation. The visual acuity of the subjects was evaluated with the Rosenbaum Vision Card before and during Coriolis stimulation. Stereopsis was measured with the Titmus stereo test. Throughout the experiments, eyeball movements were observed on a television monitor. Electrooculography (EOG) and electroencephalography (EEG) were also documented. RESULTS: Before Coriolis stimulation, the visual acuity and stereopsis of all subjects were 20/20 and 40 s of arc, respectively. During the Coriolis illusion, the visual acuity of nine subjects (50%) remained 20/20, whereas the visual acuity of the others (50%) dropped by two lines. The stereopsis of most subjects (77.8%) decreased to 800 arc-seconds or less. Rhythmic nystagmus was observed, while EOG amplitudes were significantly elevated compared with those at baseline (9.41 +/- 0.26 microv2 and 8.45 +/- 0.36 microv2, respectively). EEG activity (frequency) was also greater than at baseline (13.15 +/- 0.84 Hz and 11.94 +/- 1.20 Hz, respectively; P < 0.05). CONCLUSIONS: During Coriolis stimulation, the visual acuity of the subjects remained stable, but their stereopsis was reduced. Further study is warranted.

Heart status following high G exposure in rats and the effect of brief preconditioning.

INTRODUCTION: Acceleration on the +Gz axis increases pressure in the cardiac chambers. Our research was designed to study whether: 1) such acceleration would impair cardiac function; and 2) a "preconditioning" exposure to +Gz would protect the heart from any such effects. METHODS: There were 45 male Sprague-Dawley rats that were randomly divided into 3 groups of 15: 1) control without acceleration (CTRL); 2) exposure to 5 min of +15 Gz (EXP); and 3) pretreatment whereby the 5-min exposure was preceded by two exposures of 30 s at +15 Gz (PRE). Within each group of 15, subsets of 7 animals were used to study: 1) echocardiographic heart function or 2) myocardial injury [lactic dehydrogenase (LDH) and malondialdehyde (MDA)], and 1 animal was used to examine the histology of cardiac tissue. RESULTS: Acceleration (EXP) was found to have a significant effect on cardiac function; specifically the early diastolic myocardial velocity (Em) and systolic myocardial velocity (Sm) in both ventricles decreased in EXP compared to CTRL, while PRE significantly reduced this elect. The systolic mitral annular velocity in the left ventricular lateral wall was significantly less affected in PRE than in EXP (1.99 +/- 0.65 vs. 1.2 +/- 0.39 cm x s(-1), P = 0.017). Enzyme levels showed only minor changes. In histology, no neutrophil infiltration was found in three groups. CONCLUSIONS: These results suggest that short bouts of acceleration might offer cardiac protection. Confirmation using larger animal models may allow application of the concept to pilots preparing to undertake sustained high G maneuvers and may explain some aspects of the "G layoff" effect.

Visual fields during acute exposure to a simulated altitude of 7620 m.

BACKGROUND: The hypoxia associated with sudden exposure to high altitude is known to impair vision and may thereby affect flight safety. However, no data were available regarding hypoxic effects on visual fields. The aim of this study was to evaluate black-and-white visual field sensitivity with acute hypoxia during acute exposure to a simulated altitude of 7620 m. METHODS: Subjects were 15 male pilots 26-39 yr of age. We measured arterial oxygen saturation (S(aO2)%) using transdermal pulse oximetry while the visual field was measured within a 30 degrees eccentricity in the right eye by computerized perimetry. The subject breathed 100% O2 for 30 min before and during chamber ascent, then removed his mask while measurements were performed. RESULTS: The S(aO2)% and visual field sensitivities (mean +/- SD) at ground level were 99.1 +/- 0.4% and 43.9 +/- 2.1 dB, respectively. During hypoxia, the S(aO2)% dropped to 64.0 +/- 5.4% within 3 min. Mean visual sensitivity was significantly reduced by 7.2 +/- 1.6 dB. Furthermore, peripheral sensitivity was slightly but significantly more diminished than central sensitivity. CONCLUSIONS: Severe acute hypoxia reduces central and moderate peripheral black-and-white vision by a factor of two with the strongest effect in the periphery.

An electromyographic assessment of the anti-G straining maneuver.

BACKGROUND: The anti-G straining maneuver (AGSM), used by aircrew to enhance their +Gz tolerance and to reduce the potential risk of G-induced loss of consciousness, has been recognized as an effective technique. The purpose of this study was to establish an objective tool to evaluate the effectiveness of an aircrew member's AGSM. METHODS: There were 20 healthy subjects who participated in the study, including 8 senior aviation physiological trainers and 12 trainees. The former were familiar with the anti-G maneuver and had experienced high +Gz exposure, the latter had never been exposed to any high +Gz stress before the study. The analytic method of electromyography (EMG) was used to investigate the physical characteristics of the L-1 AGSM. RESULTS: Comparison of the EMG data from the two groups indicated that the mean duration of a breathing cycle of the trainer group was significantly longer than that of the trainee group (p < 0.001). The buccinator was the muscle that had the most rapid firing rate in both groups (p < 0.001). The trainer group had a significantly faster firing rate of the buccinator than the trainee group (p = 0.03). In addition, the trainee group performed the AGSM with a firing sequence of muscles that was different from that of the trainer group. CONCLUSIONS: An automated and quantitative system based on EMG can be used during AGSM training to augment or replace the current subjective evaluation of the trainee's performance.

Contrast sensitivity after +Gz acceleration.

BACKGROUND: This study was designed to determine the extent and duration of contrast sensitivity (CS) loss after high sustained +Gz acceleration in a centrifuge. METHODS: The subjects were 12 healthy male flight surgeons between 20 and 22 (mean = 21.1) yr of age. The human centrifuge at the Aviation Physiology Research Laboratory in Tainan, Taiwan, was used to expose the subjects to an acceleration profile. Each subject experienced three centrifuge runs made up of one gradual onset and two rapid onset profiles. Contrast sensitivity (CS) was measured before, and at 5 min, 10 min, and 20 min for the right eye; and 7 min, 12 min, and 22 min for the left eye after the acceleration. Both eyes were measured with the right eye being tested first. RESULTS: There was a generalized depression of CS at 5-12 min for both eyes. The depression was more severe at low and medium frequencies (1.5, 3.0, 6.0 cycles per degree, cpd) than at a high spatial frequency (18.0 cpd). There was a significant decrease in CS of the right eye at 1.5 cpd (p < 0.05 between control and 5 min), and on the left eye at 3.0 cpd (p < 0.05 between control and 7 min, p < 0.05 between control and 12 min) and 6.0 cpd (p < 0.05 between control and 12 min). The CS loss was more obvious at 5-12 min for both eyes, and there was only partial recovery at 22 min after the acceleration. CONCLUSIONS: These results demonstrated that +Gz acceleration is associated with CS loss. The recovery time was greater than expected. Factors other than ocular blood flow may be involved in the prolonged CS loss.