Improved discrimination of COVID-19 based on data enhancement technology and an information balance feature selection (INB) method.

The coronavirus disease (COVID-19) ravaged the world in late 2019 and posed a serious threat to human life and property destruction on a global scale. In this paper, the Wasserstein generative adversarial network with gradient penalty (WGAN-GP) method was selected for balancing the data sample, and an information balance feature selection (INB) method was first proposed to realize the accurate discrimination of COVID-19 saliva samples based on the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The results of the experiment showed that the INB method obtained higher classification accuracy than the traditional feature selection methods in both the original spectrum and the second-order derivative spectrum, especially in the second-order derivative spectrum where all the indexes reached about 85 %. In addition, the combination of WGAN_GP data augmentation and the INB method resulted in an accuracy of 88.7 % for the original spectrum and even 90.6 % for the second-order derivative spectrum. According to these findings, classification research using the WGAN_GP data enhancement model may increase classification accuracy. Additionally, the ability to successfully separate COVID-19 indicates that the INB method to identify spectral data features is a workable method, which also offers a fresh viewpoint on feature selection.

Renal Embolization-Induced Uremic Swine Model for Assessment of Next-Generation Implantable Hemodialyzers.

Reliable models of renal failure in large animals are critical to the successful translation of the next generation of renal replacement therapies (RRT) into humans. While models exist for the induction of renal failure, none are optimized for the implantation of devices to the retroperitoneal vasculature. We successfully piloted an embolization-to-implantation protocol enabling the first implant of a silicon nanopore membrane hemodialyzer (SNMHD) in a swine renal failure model. Renal arterial embolization is a non-invasive approach to near-total nephrectomy that preserves retroperitoneal anatomy for device implants. Silicon nanopore membranes (SNM) are efficient blood-compatible membranes that enable novel approaches to RRT. Yucatan minipigs underwent staged bilateral renal arterial embolization to induce renal failure, managed by intermittent hemodialysis. A small-scale arteriovenous SNMHD prototype was implanted into the retroperitoneum. Dialysate catheters were tunneled externally for connection to a dialysate recirculation pump. SNMHD clearance was determined by intermittent sampling of recirculating dialysate. Creatinine and urea clearance through the SNMHD were 76-105 mL/min/m2 and 140-165 mL/min/m2, respectively, without albumin leakage. Normalized creatinine and urea clearance measured in the SNMHD may translate to a fully implantable clinical-scale device. This pilot study establishes a path toward therapeutic testing of the clinical-scale SNMHD and other implantable RRT devices.

Toward Reagent-Free Discrimination of Alzheimer's Disease Using Blood Plasma Spectral Digital Biomarkers and Machine Learning.

BACKGROUND: Alzheimer's disease (AD) is the most prevalent neurodegenerative disease. The detection of early-stage AD is particularly desirable because it would allow early intervention. However, a minimally invasive, low-cost, and accurate discrimination or diagnostic method for AD is especially difficult in the earliest stage of AD. OBJECTIVE: The aim of this research is to discover blood plasma spectral digital biomarkers of AD, develop a novel intelligent method for the discrimination of AD and accelerate the translation of Fourier transform infrared (FTIR) spectral-based disease discrimination methods from the laboratory to clinical practice. METHODS: Since vibration spectroscopy can provide the structure and chemical composition information of biological samples at the molecular level, we investigated the potential of FTIR spectral biomarkers of blood plasma to differentiate between AD patients and healthy controls. Combined with machine learning technology, we designed a hierarchical discrimination system that provides reagent-free and accurate AD discrimination based on blood plasma spectral digital biomarkers of AD. RESULTS: Accurate segregation between AD patients and healthy controls was achieved with 89.3% sensitivity and 85.7% specificity for early-stage AD patients, 92.8% sensitivity and 87.5% specificity for middle-stage AD patients, and 100% sensitivity and 100% specificity for late-stage AD patients. CONCLUSIONS: Our results show that blood plasma spectral digital biomarkers hold great promise as discrimination markers of AD, indicating the potential for the development of an inexpensive, reagent-free, and less laborious clinical test. As a result, our research outcome will accelerate the clinical application of spectral digital biomarkers and machine learning.

Active Circulating Blood Volume During Hemodialysis: A Bench Model.

Intradialytic hypotension due to excessive fluid removal is a common complication of hemodialysis. A bench model was constructed to evaluate quantification of active circulating blood volume (ACBV). The model included a central pump representing the heart and compartments to represent the central and peripheral circulation. A blood oxygenator was used to simulate lung volume and two containers represented fast and slow circulation compartments. A separate dialysis circuit with a blood pump and two ultrasound flow-dilution probes was incorporated. Vascular access was simulated with both a shunt (fistula or graft) and a central venous catheter. Hypertonic saline (5%) was circulated in the system. A bolus of isotonic saline was introduced in the dialysis circuit, which dispersed through the physiologic model. ACBV was measured by comparing the baseline dilution curve to the curve as it returned to the probes. To evaluate the sensitivity of this technique, we investigated changing cardiac output, central venous volume, shunt flow, vascular access type, and HD pump flow. Overall percentage error (mean ± SD) across all tests (n = 15 conditions, each in triplicate) was 2.6% ± 7.4%. This study demonstrates the ability to accurately measure ACBV on the bench.

Theoretical analysis of the hydrodynamic filtering system in the balaenid whales suspension feeding.

Balaenid whales are giant filter feeders that feed on the dense aggregations of prey. Through their unique oral filters, they can effectively filter water out and leave prey in their mouths. In this study, a theoretical model is established to analyze the hydrodynamic filtering system in the balaenid whales suspension feeding. First, the appropriate velocity profiles in the anteroposterior and mediolateral directions are adopted to approximate the flow field in the anteroposterior channel along the tongue (APT channel). Then, a four-stage Runge-Kutta method is used to calculate the particle trajectories and predict the corresponding filter cake profile by solving the particle motion equations. Finally, the effects of three crucial parameters, i.e. the APT channel widthDT, the fringe layer permeabilityK, and the food particle diameterdp, are discussed. The results show that the particle trajectories consist of a series of backward-outward arcs and the food particles tend to accumulate in the posterior region of the oral cavity. The growing parabolic filter cake profiles are formed except for the case of extremely low permeability. A smallDTand largeKmake the tendency of particle posterior aggregation obviously. So squeezing the tongue and having larger fringe layer permeability are both conducive to the swallowing process. But the change indphas less influence on this tendency. The proposed theoretical analysis method is a fast and low-cost calculation method. The study on the balaenid whales' filter feeding biomechanics and hydrodynamics is helpful to guide the design of the high-efficiency bionic filters.

Influence of a novel hierarchical cellular structure on the mechanical behavior: The thousands of eyes bobhi material.

The thousands of eyes Bobhis (TEB) is a natural cellular material and has ingeniously evolved hierarchical structures to resist the damage from external environment. In this study, the relationship between cellular structure and mechanical properties of the TEBs is first investigated. SEM studies reveal that the TEB hierarchically exhibit three distinct cellular structures, the filled-cells, novel-closed-cells and open-cells, which is ranging from the macroscopic (>10-3 m) to the microcosmic scale (10-4-10-6 m) respectively. Compression and shear tests indicate that such hierarchical cellular structure has intimate influence on the mechanical properties of TEB. The loads of TEB samples are decomposed through the three hierarchical cellular structures. Microscopically, the multiple micro-cracks are firstly generated from the open-cells, and the novel-closed-cells are deformed and crushed in which the multiple micro shear bands and cell walls interlocking phenomenon can be found in the tests. Macroscopically, the filled-cells are stretched and damaged with the extrusion of filler. The hierarchical cellular structure of TEB possesses excellent mechanical properties, which hinder the catastrophic failure and increase the toughness and strength. The distinct hierarchical cellular structure of TEB provides a new pathway to design bio-inspired engineering materials.

Intradialytic Symptoms and Recovery Time in Patients on Thrice-Weekly In-Center Hemodialysis: A Cross-sectional Online Survey.

RATIONALE & OBJECTIVE: Patients experience various symptoms during hemodialysis. We aimed to assess the frequency and severity of symptoms during hemodialysis and whether intradialytic symptoms are associated with recovery time postdialysis. STUDY DESIGN: An online questionnaire was sent to 10,000 patients in a National Kidney Foundation database. SETTING & PARTICIPANTS: Adult patients receiving in-center hemodialysis 3 times weekly for 3 or more months. EXPOSURE: Online questionnaire. ANALYTIC APPROACH: Tabulation of frequency and severity of events and recovery time as percent of respondents, construction of a total symptom score, followed by rank correlation analysis of symptom characteristics with total recovery time. OUTCOMES: Patient-reported intradialytic symptoms and recovery time postdialysis. RESULTS: 359 patients met screening criteria and completed the questionnaire. Mean age was 62.5 ± 13.8 years, 207 (58%) were men, 74 (21%) were black/African American, 132 (37%) had diabetes, 252 (70%) had hypertension, and 102 (28%) had a history of myocardial infarction, heart surgery, or stent placement. 311 (87%) patients had symptoms during dialysis in the previous week, with mean severity of 2.7 (range for each symptom, 1-5). The most common symptoms were fatigue/feeling washed out (62%), cramps (44%), and symptoms of low blood pressure (42%). Median time to recovery was 3 (range, 0-24) hours, and this correlated with the incidence and severity of intradialytic symptoms (P < 0.0001). 40% of patients had time to recovery times of 4 hours or longer. 1 in 3 patients reported having stopped dialysis early for intradialytic symptoms and 6% reported skipping dialysis at least once because of intradialytic symptoms. LIMITATIONS: Recall-based self-reported data with a relatively low response rate. CONCLUSIONS: A majority of patients receiving in-center hemodialysis experience symptoms such as feeling washed out, fatigue, and cramping; these may be severe and are correlated with longer recovery time following hemodialysis, as well as shortened and skipped hemodialysis sessions.

Oral cavity flow distribution and pressure drop in balaenid whales feeding: a theoretical analysis.

Balaenid whales, as continuous ram filter feeders, can efficiently separate prey from water by baleen. The feeding process of balaenid whales is extremely complex, in which the flow distribution and pressure drop in the oral cavity play a significant role. In this paper, a theoretical model coupled with oral cavity velocity and pressure in balaenid whales is established based on mass conservation, momentum conservation and pressure drop equations, considering both the inertial and the friction terms. A discrete method with section-by-section calculation is adopted to solve the theoretical model. The effects of four crucial parameters, i.e. the ratio of filtration area to inlet area (S), the Reynolds number of entrance (Re in ), the ratio of thickness to permeability of the porous media formed by the fringe layer (ϕ) and the width ratio of the anteroposterior canal within the mouth along the tongue (APT channel) to that along the lip (APL channel) (H) are discussed. The results show that, for a given case, the flow distribution and the pressure drop both show increasing trends with the flow direction. For different cases, when S is small, Re in is small and ϕ is large, a good flow pattern emerges with a smoother flow speed near the oropharynx, better drainage, better shunting and filtration, and higher energy efficiency. However, for smaller values of H, some energy efficiency is sacrificed to achieve additional average transverse flow in order to produce better shunting and filtration. The research in this paper provides a reference for the design of high-efficiency bionic filters.

Theoretical and numerical studies on a five-ray flexible pectoral fin during labriform swimming.

Natural fish have evolved with an excellent swimming performance after millions of years. Based on the flexible features of the pectoral fin, this paper focuses on the kinematics and hydrodynamics of the fin when fish are swimming stably in still water in labriform mode. The locomotion mechanism based on the morphology of the pectoral fin is applied to establish a kinematic model composed of five rays and membranes, which is adopted to control the pectoral fin to reach deformation in approximately the same way as the labriform mode. A semi-empirical theoretical model based on the kinematics is proposed to calculate the hydrodynamic force. In order to study the flow field, the numerical simulation of fluid-structure interaction is carried out and the results are validated by the present semi-empirical model, which also verifies the feasibility of the semi-empirical theoretical model for describing the dynamics of the pectoral fin under a complex water environment. In addition, the relationship between propulsion performance and locomotion parameters (e.g. frequency of motion, amplitude of flapping and rowing angle, and phase lag between flapping and rowing) of the multi-degree of freedom flexible pectoral fin is also revealed. It is found that the frequency and amplitude of the flapping angle have a significant influence on the hydrodynamic thrust, while the rowing angle and phase lag have little effect. The established models and the results provide effective tools and significant reference for the design of bionic pectoral fins.

Failure mechanism of monolayer graphene under hypervelocity impact of spherical projectile.

The excellent mechanical properties of graphene have enabled it as appealing candidate in the field of impact protection or protective shield. By considering a monolayer graphene membrane, in this work, we assessed its deformation mechanisms under hypervelocity impact (from 2 to 6 km/s), based on a serial of in silico studies. It is found that the cracks are formed preferentially in the zigzag directions which are consistent with that observed from tensile deformation. Specifically, the boundary condition is found to exert an obvious influence on the stress distribution and transmission during the impact process, which eventually influences the penetration energy and crack growth. For similar sample size, the circular shape graphene possesses the best impact resistance, followed by hexagonal graphene membrane. Moreover, it is found the failure shape of graphene membrane has a strong relationship with the initial kinetic energy of the projectile. The higher kinetic energy, the more number the cracks. This study provides a fundamental understanding of the deformation mechanisms of monolayer graphene under impact, which is crucial in order to facilitate their emerging future applications for impact protection, such as protective shield from orbital debris for spacecraft.

The SNaP system: biomechanical and animal model testing of a novel ultraportable negative-pressure wound therapy system.

BACKGROUND: Negative-pressure wound therapy is traditionally achieved by attaching an electrically powered pump to a sealed wound bed and applying subatmospheric pressure by means of gauze or foam. The Smart Negative Pressure (SNaP) System (Spiracur, Inc., Sunnyvale, Calif.) is a novel ultraportable negative-pressure wound therapy system that does not require an electrically powered pump. METHODS: Negative pressure produced by the SNaP System, and a powered pump, the wound vacuum-assisted closure advanced-therapy system (Kinetic Concepts, Inc., San Antonio, Texas), were compared in vitro using bench-top pressure sensor testing and microstrain and stress testing with pressure-sensitive film and micro-computed tomographic scan analysis. In addition, to test in vivo efficacy, 10 rats underwent miniaturized SNaP (mSNaP) device placement on open wounds. Subject rats were randomized to a system activation group (approximately -125 mmHg) or a control group (atmospheric pressure). Wound measurements and histologic data were collected for analysis. RESULTS: Bench measurement revealed nearly identical negative-pressure delivery and mechanical strain deformation patterns between both systems. Wounds treated with the mSNaP System healed faster, with decreased wound size by postoperative day 7 (51 percent versus 12 percent reduction; p < 0.05) and had more rapid complete reepithelialization (21 days versus 32 days; p < 0.05). The mSNaP device also induced robust granulation tissue formation. CONCLUSIONS: The SNaP System and an existing electrically powered negative-pressure wound therapy system have similar biomechanical properties and functional wound-healing benefits. The potential clinical efficacy of the SNaP device for the treatment of wounds is supported.

Initial clinical experience using a novel ultraportable negative pressure wound therapy device.

UNLABELLED:  Background. Traditional negative pressure wound therapy (NPWT) devices, such as the electrically powered V.A.C.® Therapy System (KCI, San Antonio, TX), are important tools in the treatment of both acute and chronic wounds. The following describes the first clinical experience using a novel, non-electrically powered, ultraportable NPWT device called the Smart Negative Pressure (SNaP™) Wound Care System (Spiracur, Sunnyvale, CA). METHODS: Twelve consecutive adult subjects with chronic wounds ranging from neuropathic wounds to venous stasis ulcers were treated with the SNaP System at an academic outpatient dermatology clinic. Subjects were followed biweekly for complications and wound healing progression over a 4-week period. RESULTS: Of the 12 subjects treated, 5 achieved complete wound healing within 4 weeks. All subjects demonstrated healing after treatment with the SNaP System, and statistically significant healing was reached at 4 weeks (P < 0.01) for patients who were able to complete the treatment protocol. Use of the SNaP System promoted cleaner wound beds with robust granulation tissue formation. There were no serious adverse events directly related to the device. The most common complaint was mild or moderate wound pain in 3 of 12 subjects. CONCLUSION: These findings support the safety and potential clinical utility of a new ultraportable NPWT device for the treatment of chronic wounds.  .

Amniotic membrane in the surgical management of acute toxic epidermal necrolysis.

OBJECTIVE: To report a new surgical technique to manage severe acute toxic epidermal necrolysis. DESIGN: Two interventional case reports. PARTICIPANTS: Two patients. Case 1: A 6-year-old boy had severe toxic epidermal necrolysis develop after being treated with trimethoprim and sulfamethoxazole for chronic otitis media. Both eyes and eyelids were affected. He underwent bilateral lysis of symblepharon and all adhesions and bilateral amniotic membrane transplantation to the entire ocular surface except the cornea. Loss of eyelid skin required transplantation of amniotic membrane to all four eyelids and strips of amniotic membrane at the eyelid margins. Case 2: An 8-year-old girl with severe toxic epidermal necrolysis associated with mycoplasma pneumonia had bilateral, diffuse keratoconjunctivitis, diffuse corneal epithelial defects, and bilateral symblepharon. Amniotic membrane transplantation was performed bilaterally, using a symblepharon ring in the left eye. INTERVENTION: Amniotic membrane transplantation. MAIN OUTCOME MEASURES: Preservation of normal ocular and eyelid surfaces and prevention of blindness. RESULTS: Case 1: Thirty-six months after bilateral ocular surgery, there is no symblepharon, good ocular surface wetting, and an uncorrected bilateral vision of 20/20. Case 2: Amniotic membrane transplantation protected both ocular surfaces and prevented conjunctival contracture without adhesion of the eyelids to the ocular surface. The central vision was preserved. There was minimal peripheral corneal vascularization and mild conjunctival scarring of the tarsal conjunctival surface 34 months postoperatively. CONCLUSIONS: These are the first cases of acute toxic epidermal necrolysis treated with amniotic membrane transplantation and the first use of the procedure on external eyelid surfaces with good healing of the eyelids. This new treatment for acute toxic epidermal necrolysis preserves normal ocular and eyelid surfaces and may prevent blindness.