NO Deficiency Compromises Inter- and Intrahemispheric Blood Flow Adaptation to Unilateral Carotid Artery Occlusion.

Carotid artery stenosis (CAS) affects approximately 5-7.5% of older adults and is recognized as a significant risk factor for vascular cognitive impairment (VCI). The impact of CAS on cerebral blood flow (CBF) within the ipsilateral hemisphere relies on the adaptive capabilities of the cerebral microcirculation. In this study, we aimed to test the hypothesis that the impaired availability of nitric oxide (NO) compromises CBF homeostasis after unilateral carotid artery occlusion (CAO). To investigate this, three mouse models exhibiting compromised production of NO were tested: NOS1 knockout, NOS1/3 double knockout, and mice treated with the NO synthesis inhibitor L-NAME. Regional CBF changes following CAO were evaluated using laser-speckle contrast imaging (LSCI). Our findings demonstrated that NOS1 knockout, NOS1/3 double knockout, and L-NAME-treated mice exhibited impaired CBF adaptation to CAO. Furthermore, genetic deficiency of one or two NO synthase isoforms increased the tortuosity of pial collaterals connecting the frontoparietal and temporal regions. In conclusion, our study highlights the significant contribution of NO production to the functional adaptation of cerebrocortical microcirculation to unilateral CAO. We propose that impaired bioavailability of NO contributes to the impaired CBF homeostasis by altering inter- and intrahemispheric blood flow redistribution after unilateral disruption of carotid artery flow.

Impact of Ionic Liquid Additives and Inorganic Fullerene-Like Tungsten Disulfide on Friction and Wear under Aqueous Environments.

Aqueous lubricants are gaining attention due to significant advantages such as being environmentally friendly, tunable, and thermally stable. The oil and gas industry can use such additives to utilize in water-based fluids for applications where small sliding velocities and large lateral forces require enhanced lubrication. This investigation aims to compare the effects of two different additives: (i) inorganic fullerene-like tungsten disulfide (IF-WS2) and (ii) an alkanolamine ionic liquid denoted as AA-IL. Both additives were paired with three different base fluids, deionized water (DIW), aqueous NaCl, and aqueous CaCl2, to measure the impact on fluids commonly utilized in the field. The addition of IF-WS2 to all three solutions resulted in a 30-60% decrease in the coefficient of friction (COF) and wear. Surface analysis by X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS) showed that the formation of a tribofilm (tungsten oxide layer) is primarily responsible for tribological improvements. The AA-IL did not show evidence of any chemical interaction. Instead, a physically bonded film of the AA-IL on the steel surface enabled the improved COF (40-50% reduction) and wear response. Both additives are effective in very small amounts and provide excellent wear and friction reduction properties.

Development of Fluorine-Free Tantalum Carbide MXene Hybrid Structure as a Biocompatible Material for Supercapacitor Electrodes.

The application of nontoxic 2D transition-metal carbides (MXenes) has recently gained ground in bioelectronics. In group-4 transition metals, tantalum possesses enhanced biological and physical properties compared to other MXene counterparts. However, the application of tantalum carbide for bioelectrodes has not yet been explored. Here, fluorine-free exfoliation and functionalization of tantalum carbide MAX-phase to synthesize a novel Ta4C3Tx MXene-tantalum oxide (TTO) hybrid structure through an innovative, facile, and inexpensive protocol is demonstrated. Additionally, the application of TTO composite as an efficient biocompatible material for supercapacitor electrodes is reported. The TTO electrode displays long-term stability over 10 000 cycles with capacitance retention of over 90% and volumetric capacitance of 447 F cm-3 (194 F g-1) at 1 mV s-1. Furthermore, TTO shows excellent biocompatibility with human-induced pluripotent stem cells-derived cardiomyocytes, neural progenitor cells, fibroblasts, and mesenchymal stem cells. More importantly, the electrochemical data show that TTO outperforms most of the previously reported biomaterials-based supercapacitors in terms of gravimetric/volumetric energy and power densities. Therefore, TTO hybrid structure may open a gateway as a bioelectrode material with high energy-storage performance for size-sensitive applications.

Outcomes of pericardiectomy for constrictive pericarditis following mediastinal irradiation.

BACKGROUND: Pericardiectomy for postradiation constrictive pericarditis has been reported to generally have unfavorable outcomes. This study sought to evaluate surgical outcomes in a large cohort of patients undergoing pericardiectomy for radiation-associated pericardial constriction. METHODS: A retrospective analysis of all patients (≥18 years) who underwent pericardiectomy for a diagnosis of constrictive pericarditis with a prior history of mediastinal irradiation from June 2002 to June 2019 was conducted. There were 100 patients (mean age 57.2 ± 10.1 years, 49% females) who met the inclusion criteria. Records were reviewed to look at the surgical approach, the extent of resection, early mortality, and late survival. RESULTS: The overall operative mortality was 10.1% (n = 10). The rate of operative mortality decreased over the study period; however, the test of the trend was not statistically significant (p = .062). Hodgkin's disease was the most common malignancy (64%) for which mediastinal radiation had been received. Only 27% of patients had an isolated pericardiectomy, and concomitant pericardiectomy and valve surgery were performed in 46% of patients. Radical resection was performed in 50% of patients, whereas 47% of patients underwent subtotal resection. Prolonged ventilation (26%), atrial fibrillation (21%), and pleural effusion (16%) were the most common postoperative complications. The overall 1, 5-, and 10-years survival was 73.6%, 53.4%, and 32.1%, respectively. Increasing age (hazard ratio, 1.044, 95% confidence interval 1.017-1.073) appeared to have a significant negative effect on overall survival in the univariate model. CONCLUSION: Pericardiectomy performed for radiation-associated constrictive pericarditis has poor long-term outcomes. The early mortality, though high (~10%), has been showing a decreasing trend in the test of time.

Fabrication and Deformation of 3D Multilayered Kirigami Microstructures.

Mechanically guided 3D microassembly with controlled compressive buckling represents a promising emerging route to 3D mesostructures in a broad range of advanced materials, including single-crystalline silicon (Si), of direct relevance to microelectronic devices. During practical applications, the assembled 3D mesostructures and microdevices usually undergo external mechanical loading such as out-of-plane compression, which can induce damage in or failure of the structures/devices. Here, the mechanical responses of a few mechanically assembled 3D kirigami mesostructures under flat-punch compression are studied through combined experiment and finite element analyses. These 3D kirigami mesostructures consisting of a bilayer of Si and SU-8 epoxy are formed through integration of patterned 2D precursors with a prestretched elastomeric substrate at predefined bonding sites to allow controlled buckling that transforms them into desired 3D configurations. In situ scanning electron microscopy measurement enables detailed studies of the mechanical behavior of these structures. Analysis of the load-displacement curves allows the measurement of the effective stiffness and elastic recovery of various 3D structures. The compression experiments indicate distinct regimes in the compressive force/displacement curves and reveals different geometry-dependent deformation for the structures. Complementary computational modeling supports the experimental findings and further explains the geometry-dependent deformation.

Fast Self-Healing of Polyelectrolyte Multilayer Nanocoating and Restoration of Super Oxygen Barrier.

A self-healable gas barrier nanocoating, which is fabricated by alternate deposition of polyethyleneimine (PEI) and polyacrylic acid (PAA) polyelectrolytes, is demonstrated in this study. This multilayer film, with high elastic modulus, high glass transition temperature, and small free volume, has been shown to be a super oxygen gas barrier. An 8-bilayer PEI/PAA multilayer assembly (≈700 nm thick) exhibits an oxygen transmission rate (OTR) undetectable to commercial instrumentation (<0.005 cc (m-2 d-1 atm-1 )). The barrier property of PEI/PAA nanocoating is lost after a moderate amount of stretching due to its rigidity, which is then completely restored after high humidity exposure, therefore achieving a healing efficiency of 100%. The OTR of the multilayer nanocoating remains below the detection limit after ten stretching-healing cycles, which proves this healing process to be highly robust. The high oxygen barrier and self-healing behavior of this polymer multilayer nanocoating makes it ideal for packaging (food, electronics, and pharmaceutical) and gas separation applications.

Adaptation of the cerebrocortical circulation to carotid artery occlusion involves blood flow redistribution between cortical regions and is independent of eNOS.

Cerebral circulation is secured by feed-forward and feed-back control pathways to maintain and eventually reestablish the optimal oxygen and nutrient supply of neurons in case of disturbances of the cardiovascular system. Using the high temporal and spatial resolution of laser-speckle imaging we aimed to analyze the pattern of cerebrocortical blood flow (CoBF) changes after unilateral (left) carotid artery occlusion (CAO) in anesthetized mice to evaluate the contribution of macrovascular (circle of Willis) vs. pial collateral vessels as well as that of endothelial nitric oxide synthase (eNOS) to the cerebrovascular adaptation to CAO. In wild-type mice CoBF reduction in the left temporal cortex started immediately after CAO, reaching its maximum (-26%) at 5-10 s. Thereafter, CoBF recovered close to the preocclusion level within 30 s indicating the activation of feed-back pathway(s). Interestingly, the frontoparietal cerebrocortical regions also showed CoBF reduction in the left (-17-19%) but not in the right hemisphere, although these brain areas receive their blood supply from the common azygos anterior cerebral artery in mice. In eNOS-deficient animals the acute CoBF reduction after CAO was unaltered, and the recovery was even accelerated compared with controls. These results indicate that 1) the Willis circle alone is not sufficient to provide an immediate compensation for the loss of one carotid artery, 2) pial collaterals attenuate the ischemia of the temporal cortex ipsilateral to CAO at the expense of the blood supply of the frontoparietal region, and 3) eNOS, surprisingly, does not play an important role in this CoBF redistribution.

One-year Results of Minimally Invasive Sutured Fixation of the Slipped Ribs in the Pediatric Population.

PURPOSE: Costal cartilage resection with or without rib resection is the gold standard surgery for slipping rib syndrome. Minimally invasive restoration of normal anatomy via nonabsorbable sutures has been described in the adult population with encouraging results. We sought to assess the efficacy of minimally invasive sutured fixation of the hypermobile rib in the pediatric population. METHODS: A retrospective review was performed at Mayo Clinic involving 31 pediatric patients diagnosed with slipped rib syndrome. Minimally invasive sutured open reduction internal fixation was performed between 2020 and 2022. The standardized Örebro Musculoskeletal Pain Screening Questionnaire was given at dedicated time points pre- and post-operatively to assess efficacy. Significance was determined via the Wilcoxon rank sum test. RESULTS: SRS was diagnosed clinically in 31 patients (24 females, 7 males, 1220 years-old). Symptoms were present for an average of 18.9 months and patients had seen an average of 4.7 specialists. Traumatic causes were identified in three patients and eight patients had hypermobility. At one month follow up, there were no surgical complications and patients reported significantly less pain (p < 0.001). Preoperative analgesics reduced by 80%. Ultimately, seven patients underwent a second operation; three patients underwent a third operation; one patient underwent five total operations. Recurrent pain was reported in six patients. Only nine patients followed-up at 1-year post-operation. CONCLUSION: Pediatric patients with SRS demonstrated an early positive response to suture fixation without costal cartilage excision. Reoperation and recurrent pain, however, remain significant in this population. LEVEL OF EVIDENCE: Level IV. TYPE OF STUDY: Case series with no comparison group.

Acute type A aortic dissection in adolescents and young adults under 30 years of age: demographics, aetiology and postoperative outcomes of 139 cases.

OBJECTIVES: The prevalence and aetiology of acute aortic dissection type A (AADA) in patients ≤30 years is unknown. The aims of this clinical study were to determine the prevalence and potential aetiology of AADA in surgically treated patients ≤30 years and to evaluate the respective postoperative outcomes in this selective group of patients in a large multicentre study. METHODS: Retrospective data collection was performed at 16 participating international aortic institutions. All patients ≤30 years at the time of dissection onset were included. The postoperative results were analysed with regard to connective tissue disease (CTD). RESULTS: The overall prevalence of AADA ≤30 years was 1.8% (139 out of 7914 patients), including 51 (36.7%) patients who were retrospectively diagnosed with CTD. Cumulative postoperative mortality was 8.6%, 2.2% and 1.4%. Actuarial survival was 80% at 10 years postoperatively. Non-CTD patients (n = 88) had a significantly higher incidence of arterial hypertension (46.6% vs 9.8%; P < 0.001) while AADA affected the aortic root (P < 0.001) and arch (P = 0.029) significantly more often in the CTD group. A positive family history of aortic disease was present in 9.4% of the study cohort (n = 13). CONCLUSIONS: The prevalence of AADA in surgically treated patients ≤30 years is <2% with CTD and arterial hypertension as the 2 most prevalent triggers of AADA. Open surgery may be performed with good early results and excellent mid- to long-term outcomes.

Multifunctional Quasi-Solid-State Zinc-Sulfur Battery.

The introduction of structural energy storage devices into emerging markets, such as electric vehicles, is predominately hindered by weak energy density, safety concerns, and immaturity of the field in materials. Herein, fabrication and testing of a freeze-resistant, multifunctional quasi-solid-state zinc-sulfur battery (ZnS) are reported. To this end, an electrostatic spray coating technique was used to deposit a thin layer of sulfur on the highly porous, unidirectional activated carbon nanofibers (A-CNFs) as a load-bearing cathode. This technique could fill micro- and mesopores, and microsized channels with sulfur, achieving an extensive sulfur loading of 60 wt %. Several drawbacks of structural energy storage devices (applicability under varied climate conditions, poor electrochemical performance and mechanical properties) are addressed by initiating an antifreezing hydrogel electrolyte with a failure strain of over 200%. This electrolyte possesses ethylene glycol and an I2 additive as an antifreezing agent and redox mediator, respectively. The as-assembled ZnS battery offers a high energy density of 283 Wh/kg based on the CNF-S cathode (149 Wh/kg based on the ZnS cell) and mechanical properties beyond state-of-the-art structural energy storage devices with a tensile strength of 377 MPa, Young's modulus of 16.7 GPa, and energy-to-failure of 4.5 MJ/m3. The electrochemomechanical properties of the ZnS battery were also investigated to elucidate the effects of electrochemical energy storage on mechanical properties and vice versa. Overall, the ZnS battery outperforms state-of-the-art structural energy storage devices in terms of energy storage and load-bearing capabilities.

Development of a controlled-atmosphere, rapid-cooling cryogenic chamber for tribological and mechanical testing.

Mechanical testing of seals, bearing materials, and mechanisms in cryogenic environments is a rapidly growing field of research, as it promises improvements in equipment performance and reliability for applications such as space exploration, liquid hydrocarbon storage, and superconducting devices. Cooling of test equipment is usually performed within a well-insulated test chamber, via direct or indirect evaporation of liquid cryogen. State-of-the-art equipment is frequently insufficient for rigorous testing, being expensive and cumbersome, cooling slowly, struggling to replicate relevant environmental conditions, and/or failing to reach the temperature of the cryogen. Herein, we employ a rapid prototyping approach using polymer 3D printing to iteratively refine cryogen-based cooling of a tribometer. The final design greatly exceeds the minimum temperature of state-of-the-art equipment, cooling a chamber to liquid nitrogen temperatures (-196 °C) while maintaining dry test conditions. When modified for use on a cryogenic tensile tester, the design cools to -150 °C in 149 s, significantly improving upon state-of-the-art performance. By utilizing this 3D-printed equipment, we find that components produced via Fused Deposition Modeling with unmodified, commodity polylactic acid have favorable mechanical properties in a cryogenic environment: tensile strength of 110 MPa, elongation at break of 10%, and specific wear of 5.6 × 10-5 mm3/Nm against stainless steel. By leveraging 3D printing for rapid manufacture of production-quality parts, highly refined cooling chamber designs have been experimentally developed for both a tribometer and a load frame in rapid succession, enabling significant improvements in cryogenic test capabilities.

Pediatric surgical rib fixation: A collected case series of a rare entity.

BACKGROUND: Rib fractures are uncommon in children and are markers of extreme traumatic force from high-energy or nonaccidental etiology. Traditional care includes nonoperative management, with analgesia, ventilator support, and pulmonary physiotherapy. Surgical stabilization of rib fractures (SSRFs) has been associated with improved outcomes in adults. In children, SSRF is performed and its role remains unclear, with data only available from case reports. We created a collected case series of published pediatric SSRF cases, with the aim to provide a descriptive summary of the existing data. METHODS: Published cases of SSRF following thoracic trauma in patients younger than 18 years were identified. Collected data included demographics, injury mechanism, associated injuries, surgical indication(s), surgical technique, time to extubation, postoperative hospital stay, and postoperative follow-up. RESULTS: Six cases were identified. All were boys, with age range 6 to 16 years. Injury mechanism was high-energy blunt force in all cases, and all patients suffered multiple associated injuries. Five of six cases were related to motor vehicles, and one was horse-related. Indication(s) for surgery included ventilator dependence in five, significant chest deformity in two, and poor pain control in one case. Plating systems were used for rib stabilization in five of six cases, while intramedullary splint was used in one. All patients were extubated within 7 days following SSRF, and all were discharged by postoperative Day 20. On postoperative follow-up, no SSRF-related major issues were reported. One patient underwent hardware removal at 2 months. CONCLUSION: Surgical stabilization of rib fractures in children is safe and feasible, and should be considered as an alternative to nonoperative therapy in select pediatric thoracic trauma cases. Potential indications for SSRF in pediatric patients include poor pain control, chest wall deformity, or ventilator dependence. Further studies are needed to establish the role and possible benefits of SSRF in pediatric thoracic trauma. LEVEL OF EVIDENCE: Collected case series, level V.

Enabling Selectively Tunable Mechanical Properties of Graphene Oxide/Silk Fibroin/Cellulose Nanocrystal Bionanofilms.

Enhancing and manipulating the mechanical properties of graphene oxide (GO)-based structures are challenging because the GO assembly is easily delaminated. We develop nacre-like bionanofilms whose in-plane mechanical properties can be manipulated through water vapor annealing without influencing their mechanical properties in the thickness direction. These bionanofilms are prepared from GO, silk fibroin (SF), and cellulose nanocrystals (CNCs) via a spin-assisted layer-by-layer assembly. The postannealing mechanical properties of the films are determined with atomic force microscopy (AFM) bending and nanoindentation, and it is confirmed that the mechanical properties of the bionanofilms are altered only in the in-plane direction. While AFM bending shows Young's moduli of 26.9, 36.3, 24.3, and 41.4 GPa for 15, 15 annealed, 30, and 30 annealed GO/SF/CNC trilayers, nanoindentation shows reduced moduli of 19.5 ± 2.6 and 19.5 ± 2.5 GPa before and after annealing, respectively. The unaltered mechanical properties of the bionanofilms along the thickness direction after annealing can be attributed to the CNC frame in the SF matrix acting as a support against stress in the thickness direction, while annealing reorganizes the bionanofilm structure. The tunability of the bionanofilms' mechanical properties in only one direction through structure manipulation can lead to various applications, such as e-skin, wearable sensors, and human-machine interaction devices.

Novel Innovations for Ventricular Assist Device Infection.

Device infection is a major potential complication following ventricular assist device implantation and can lead to devastating consequences. The treatment options are few and often challenging to implement. The most durable option may require device exchange to obtain adequate source control. Due to the prolonged support times offered by the new left ventricular assist devices (LVADs), there is concern that the number of patients that will eventually require repeated device exchanges for device infection will increase. The benefit of medical antibiotic therapy alone is limited and is frequently unsuccessful. Surgical treatment strategies that improve outcomes by eliminating the infection and by preventing infection recurrence are needed. We report a case of a third-time LVAD exchange (4th device implant) for device infection within eight years of the index implant, and we briefly discuss the role of the greater omentum in the surgical treatment of this complication.

Effects of SiO2 content on the nanomechanical properties of CoCrPt-SiO2 granular films.

CoCrPt material is used for perpendicular magnetic recording media due to its high magneto-crystalline anisotropy that brings good thermal stability on the media. The addition of SiO2 between the CoCrPt grains offers benefits including lower noise and better thermal stability. It has been reported that the SiO2 content has strong effects on the media's recording performance such as coercivity, anisotropy and noise. In this work, we focus on studying the effects of the SiO2 content on the nanomechanical properties of the media which are critical for the head-disk interface reliability. Variations of these properties with SiO2 content provide guidelines for optimum designs considering both recording and mechanical interface performance.

Preemptive Extracorporeal Life Support for Surgical Treatment of Severe Constrictive Pericarditis.

BACKGROUND: Surgical treatment of constrictive pericarditis (CP) is particularly challenging because of the increased risk of right heart failure. The necessity of postoperative extracorporeal life support (ECLS) can result in mortality rates of 100%. Preemptive implantation of ECLS may improve postoperative outcomes; however, no data are currently available on its use. We conducted a retrospective study to evaluate the feasibility of our strategy. METHODS: Between September 2012 and June 2016, ECLS was established percutaneously through the groin vessels in 12 individually selected patients with high-risk CP immediately before pericardiectomy in the operating theater as part of the surgical strategy. Prolonged weaning was performed in the intensive care unit. Demographic characteristics, perioperative data, and survival were analyzed. RESULTS: The median patient age was 61.5 years (first quartile, third quartile: 51.3, 68.5 years), with a preoperative central venous pressure of 24 mm Hg (first quartile, third quartile: 21, 28 mm Hg). Furthermore, the pulmonary artery pressure was greater than 60 mm Hg in 50% of patients and a dip plateau sign existed in 75% before surgery. The median duration of ECLS therapy was 132 hours (first quartile, third quartile: 96, 168 hours) with a length of stay on the intensive care unit of 10 days (first quartile, third quartile: 7.0, 16.8 days). There was no intraoperative death. The cumulative 30-day, 1-year, and 5-year survival rates were 83% ± 11%, 75% ± 13%, and 75% ± 13%, respectively. CONCLUSIONS: From our real-world data, preemptive use of perioperative ECLS, assigned by individual team decision in selected patients with severe CP, is a feasible and safe strategy.

Dynamic adhesive force measurements under vertical and horizontal motions of interacting rough surfaces.

An instrument to measure dynamic adhesive forces between interacting rough surfaces has been developed. It consists of four parts, namely, main instrument body, vertical positioning system with both micrometer and nanometer positioning accuracies, horizontal positioning system with nanometer positioning accuracy, and custom-built high-resolution, and high dynamic bandwidth capacitive force transducer. The vertical piezoelectric actuator (PZT) controls the vertical (approaching and retracting) motion of the upper specimen, while the horizontal PZT controls the horizontal (reciprocal) motion of the lower specimen. The force transducer is placed in line with the upper specimen and vertical PZT, and directly measures the adhesive forces with a root-mean-square load resolution of 1.7 microN and a dynamic bandwidth of 1.7 kHz. The newly developed instrument enables reliable measurements of near-contact and contact adhesive forces for microscale devices under different dynamic conditions. Using the developed instrument, dynamic pull-in and pull-off force measurements were performed between an aluminum-titanium-carbide sphere and a 10 nm thick carbon film disk sample. Three different levels of contact force were investigated; where for each contact force level the vertical velocity of the upper sample was varied from 0.074 to 5.922 microms, while the lower sample was stationary. It was found that slower approaching and retracting velocities result in higher pull-in and pull-off forces. The noncontact attractive force was also measured during horizontal movement of the lower sample, and it was found that the periodic movements of the lower disk sample also affect the noncontact surface interactions.

A microelectromechanical systems (MEMS) force-displacement transducer for sub-5 nm nanoindentation and adhesion measurements.

We present a highly sensitive force-displacement transducer capable of performing ultra-shallow nanoindentation and adhesion measurements. The transducer utilizes electrostatic actuation and capacitive sensing combined with microelectromechanical fabrication technologies. Air indentation experiments report a root-mean-square (RMS) force resolution of 1.8 nN and an RMS displacement resolution of 0.019 nm. Nanoindentation experiments on a standard fused quartz sample report a practical RMS force resolution of 5 nN and an RMS displacement resolution of 0.05 nm at sub-10 nm indentation depths, indicating that the system has a very low system noise for indentation experiments. The high sensitivity and low noise enables the transducer to obtain high-resolution nanoindentation data at sub-5 nm contact depths. The sensitive force transducer is used to successfully perform nanoindentation measurements on a 14 nm thin film. Adhesion measurements were also performed, clearly capturing the pull-on and pull-off forces during approach and separation of two contacting surfaces.

An improved meniscus surface model for contacting rough surfaces.

Based on the Extended-Maugis-Dugdale (EMD) elastic theory, a single asperity capillary meniscus model considering asperity deformation due to both contact and adhesive forces was developed. Specifically included in the single asperity meniscus model was the solid surface interaction inside the contact area. Subsequently, the single asperity model was coupled with a statistical roughness surface model to develop an improved meniscus surface model applicable to a wide-range of humidity levels and adhesion parameter values. Simulations were performed using typical surfaces found in microelectromechanical systems (MEMS) and magnetic storage hard disk drives to examine the effects of surface roughness and relative humidity. It was found that smoother surfaces give rise to higher adhesive and pull-off forces, and at higher relative humidity levels, the capillary force governs the adhesive behavior. As the humidity decreases, the solid surface interaction increases and needs to be included in the total meniscus adhesion. By integrating the adhesive force-displacement curves, the adhesion energy per unit area was calculated for MEMS surfaces and favorably compared with reported experimental data.