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In recent years, there has been a progressive trend towards less invasive technologies for detecting metastatic cancer and guiding therapy with the goal of lower morbidity, better outcomes, and superior cosmetic appearance than traditional methods. This mini-review examines three emerging noninvasive hybrid technologies for detecting primary cancer, metastasis and guiding thermal therapy. Real-time thermoacoustic imaging and thermometry potentially provides valuable and critical feedback for guiding focused microwave ablation therapy. Label-free photoacoustic monitoring of cancer cells is a promising clinical diagnostic and theranostic tool for detecting metastatic disease and monitoring the response to therapy. Finally, immunologically targeted gold nanoparticles combined with photoacoustic imaging is able to detect lymph node micrometastasis in mouse models of breast cancer. These emerging techniques have the potential to improve the decision to biopsy, provide more accurate prognosis, and enhance the efficacy of therapy for early and late stage cancers.

As a real-time high resolution imaging modality, pulse echo ultrasound (US) is a common screening tool for breast, thyroid, and other types of cancer. However, US has low specificity for detecting cancer due to poor contrast in soft tissue. Hybrid US techniques like photoacoustic (PA) and thermoacoustic (TA) imaging provide additional sources of contrast for cancer detection but are still mostly independent research tools not readily available in the clinic. The goal of this study was to develop and demonstrate advantages of a real-time trimodal imaging system that combines US, PA, and TA integrated into a commercial US system. Our trimodal system provided real-time feedback on near-infrared absorbing contrast agents, water content, and acoustic backscatter for structure, all important contrast features for accurate diagnostics and feedback during thermal therapy. Real-time video of the pumped Methylene Blue (MB, 0.025% in diH2O) was captured at a velocity resolution of 280 mm/s. Spectrally probed MB resulted in unique PA spectral responses, as well as qualitative images in false colors. Thermometry revealed a correlation between the PA and TA signal responses and MB temperature each with $\mathrm{R}^{2}=0.99$ . By combining all three modalities, the system is capable of detecting different sources of contrast, including acoustic backscatter (US), optical (PA) and microwave (TA) absorption, and changes in temperature (PA and TA).

Tissue engineering has gained considerable attention in the development of small diameter tissue engineered vascular grafts (TEVGs) for treating coronary heart disease. A properly designed acellular and biodegradable TEVG must encourage the infiltration and growth of vascular smooth muscle cells (SMCs). Our group has previously shown that increasing levels of TGFβ2 can differentially modulate SMC migration and proliferation. In this study, tubular electrospun scaffolds loaded with TGFβ2 were fabricated using various ratios of gelatin/polycaprolactone (PCL), resulting in scaffolds with porous nano-woven architecture suitable for tissue ingrowth. Scaffold morphology, degradation rate, TGβ2 release kinetics, and bioactivity were assessed. TGFβ2 was successfully integrated into the electrospun biomaterial that resulted in a differential release profile depending on the gelatin/PCL ratio over the course of 42 days. Higher TGFβ2 elution was obtained in scaffolds with higher gelatin content, which may be related to the biodegradation of gelatin in culture media. The biological activity of the released TGFβ2 was evaluated by its ability to affect SMC proliferation as a function of its concentration. SMCs seeded on TGFβ2-loaded scaffolds also showed higher densities and infiltration after 5 days in culture as compared to scaffolds without TGFβ2. Our results demonstrate that the ratio of synthetic and natural polymers in electrospun blends can be used to tune the release of TGFβ2. This method can be used to intelligently modulate the SMC response in gelatin/PCL scaffolds making the TGFβ2-loaded conduits attractive for cardiovascular tissue engineering applications.

Thermoacoustic (TA) thermometry requires calibration to establish the relationship between the change in TA signal with the change in temperature. Previous studies have used a priori slopes values (i.e. TA signal vs temperature), typically determined experimentally from previously performed standard calibrations. However, standard calibration requires more than one test and is not robust to changing sample orientation or composition. The goal of this study is to compare a previously studied self-calibration method to the standard calibration method in estimating temperature using real-time 3D TA thermometry in bovine udder tissue kept in the same orientation for both methods. The self-calibration and standard methods estimated temperatures of the udder sample during localized heating with a normalized root mean square errors (NRMSE) of 7.1% and 8.4%, respectively. The predicted temperatures produced by the self-calibration method were less variable than the standard method. Overall, the qualitative and quantitative results comparing predicted change in temperature suggested that self-calibration is as accurate as standard calibration with less variability and less experimentation. These advantages point to self-calibration being a more preferred method to provide temperature predictions for feedback control in future breast cancer ablation therapy.

Thermoacoustic (TA) imaging is a modality where pulsed microwaves are used to generate ultrasound waves in tissue, which are highly correlated with temperature. This study uses a self-calibration approach to improve the estimation of temperature using 3D real-time TA thermometry in porcine tissue during localized heating. The self-calibration method estimated temperatures at eight embedded thermocouple locations with a normalized root-mean-square error of 3.25 ± 2.08 % . The results demonstrate that the method has the suitable accuracy and resolution to provide feedback control for breast cancer ablation therapy.

Coronary artery bypass grafts used to treat coronary artery disease (CAD) often fail due to compliance mismatch. In this study, we have developed an experimental/computational approach to fabricate an acellular biomimetic hybrid tissue engineered vascular graft (TEVG) composed of alternating layers of electrospun porcine gelatin/polycaprolactone (PCL) and human tropoelastin/PCL blends with the goal of compliance-matching to rat abdominal aorta, while maintaining specific geometrical constraints. Polymeric blends at three different gelatin:PCL (G:PCL) and tropoelastin:PCL (T:PCL) ratios (80:20, 50:50, and 20:80) were mechanically characterized. The stress–strain data were used to develop predictive models, which were used as part of an optimization scheme that was implemented to determine the ratios of G:PCL and T:PCL and the thickness of the individual layers within a TEVG that would compliance match a target compliance value. The hypocompliant, isocompliant, and hypercompliant grafts had target compliance values of 0.000256, 0.000568, and 0.000880 mmHg−1, respectively. Experimental validation of the optimization demonstrated that the hypercompliant and isocompliant grafts were not statistically significant from their respective target compliance values (p-value = 0.37 and 0.89, respectively). The experimental compliance values of the hypocompliant graft were statistically significant than their target compliance value (p-value = 0.047). We have successfully demonstrated a design optimization scheme that can be used to fabricate multilayered and biomimetic vascular grafts with targeted geometry and compliance.

Controlled environments have long played an important role in the field of agriculture because they enable growers to more precisely regulate not only the quantity of a crop but the quality as well. Currently, most controlled environments rely on mechanical systems to regulate temperature and relative humidity within the controlled space, but these systems can be costly to install and operate. For this reason, researchers have begun investigating the efficacy of using high-pressure fogging systems and their associated control strategies in naturally ventilated greenhouses as an alternative to mechanical cooling methods. However, conducting detailed analyses of a greenhouse’s aerodynamics requires carefully arrayed instruments, a consideration of many different scenarios, and a significant amount of time to compile data, not to mention the monetary cost of experimental analysis. The objective of this study, then, was to develop a 3D computational fluid dynamics (CFD) model capable of more efficiently analyzing the movement of air in a naturally ventilated greenhouse equipped with a high-pressure fogging system. The overall model included five subunits: (1) a porous media model to simulate the ways that a crop canopy will affect airflow, (2) a solar load model and (3) a discrete ordinates radiation model to simulate solar radiation, (4) a species transport and discrete phase model to simulate evaporation of droplets, and (5) an evapotranspiration (ET) model integrated with a user-defined function (UDF). The overall model predicted temperature and relative humidity within the greenhouse with percentage errors for temperature and relative humidity of 5.7% to 9.4% and 12.2% to 26.9%, respectively (given a 95% confidence interval). The average percent error between the simulated and measured ET was around 8%, and the CFD-simulated stomatal and aerodynamic resistances agreed well and were within the ranges indicated by earlier research. Having validated the overall model with experimental data, we then used a 2 4 full-factorial design to determine the effects on climate uniformity produced by four factors: position of the side vent, position of the vertical sprayer nozzles, position of the horizontal sprayer nozzles, and angle of the nozzle. On the basis of our statistical analysis, we concluded that “horizontal nozzle position” was the most significant factor for climate uniformity, while the least significant factor among those evaluated was “side vent opening.”

Computational fluid dynamics (CFD), numerical analysis and simulation tools of fluid flow processes have emerged from the development stage and become nowadays a robust design tool. It is widely used to study various transport phenomena which involve fluid flow, heat and mass transfer, providing detailed information for spatial and temporal distributions of flow speed and direction, pressure, temperature and species concentration. The CFD tools provide a cost-effective way of carrying out equipment and process design and optimization, and can reduce risk in equipment modification and process scale-up. In recent years, CFD modeling has been gaining attraction from the agri-food industry. The present paper provides a state-of-the-art review on various CFD applications to improve crop farming systems such as, soil tillage, sprayers, harvesting, machinery, and greenhouses. The challenges faced by modelers using CFD in precision crop production are discussed and possibilities for incorporating the CFD models in decision support tools for Precision Farming are highlighted.

Cardiovascular disease (CVD) is the leading cause of death for Americans. As coronary artery bypass graft surgery (CABG) remains a mainstay of therapy for CVD and native vein grafts are limited by issues of supply and lifespan, an effective readily available tissue-engineered vascular graft (TEVG) for use in CABG would provide drastic improvements in patient care. Biomechanical mismatch between vascular grafts and native vasculature has been shown to be the major cause of graft failure, and therefore, there is need for compliance-matched biocompatible TEVGs for clinical implantation. The current study investigates the biaxial mechanical characterization of acellular electrospun glutaraldehyde (GLUT) vapor-crosslinked gelatin/fibrinogen cylindrical constructs, using a custom-made microbiaxial optomechanical device (MOD). Constructs crosslinked for 2, 8, and 24 hrs are compared to mechanically characterized porcine left anterior descending coronary (LADC) artery. The mechanical response data were used for constitutive modeling using a modified Fung strain energy equation. The results showed that constructs crosslinked for 2 and 8 hrs exhibited circumferential and axial tangential moduli (ATM) similar to that of the LADC. Furthermore, the 8-hrs experimental group was the only one to compliance-match the LADC, with compliance values of 0.0006±0.00018 mm Hg−1 and 0.00071±0.00027 mm Hg−1, respectively. The results of this study show the feasibility of meeting mechanical specifications expected of native arteries through manipulating GLUT vapor crosslinking time. The comprehensive mechanical characterization of cylindrical biopolymer constructs in this study is an important first step to successfully develop a biopolymer compliance-matched TEVG.

Coronary heart disease is a leading cause of death among Americans for which coronary artery bypass graft (CABG) surgery is a standard surgical treatment. The success of CABG surgery is impaired by a compliance mismatch between vascular grafts and native vessels. Tissue engineered vascular grafts (TEVGs) have the potential to be compliance matched and thereby reduce the risk of graft failure. Glutaraldehyde (GLUT) vapor-crosslinked gelatin/fibrinogen constructs were fabricated and mechanically tested in a previous study by our research group at 2, 8, and 24 hrs of GLUT vapor exposure. The current study details a computational method that was developed to predict the material properties of our constructs for crosslinking times between 2 and 24 hrs by interpolating the 2, 8, and 24 hrs crosslinking time data. matlab and abaqus were used to determine the optimal combination of fabrication parameters to produce a compliance matched construct. The validity of the method was tested by creating a 16-hr crosslinked construct of 130 μm thickness and comparing its compliance to that predicted by the optimization algorithm. The predicted compliance of the 16-hr construct was 0.00059 mm Hg−1 while the experimentally determined compliance was 0.00065 mm Hg−1, a relative difference of 9.2%. Prior data in our laboratory has shown the compliance of the left anterior descending porcine coronary (LADC) artery to be 0.00071 ± 0.0003 mm Hg−1. Our optimization algorithm predicts that a 258-μm-thick construct that is GLUT vapor crosslinked for 8.1 hrs would match LADC compliance. This result is consistent with our previous work demonstrating that an 8-hr GLUT vapor crosslinked construct produces a compliance that is not significantly different from a porcine coronary LADC.

Purpose The purpose of this study was to quantify the biomechanical response of human posterior ocular tissues from donors of various racioethnic groups to better understand how differences in these properties may play a role in the racioethnic health disparities known to exist in glaucoma. Methods Sequential digital image correlation (S-DIC) was used to measure the pressure-induced surface deformations of 23 normal human posterior poles from three racioethnic groups: African descent (AD), European descent (ED), and Hispanic ethnicity (HIS). Regional in-plane principal strains were compared across three zones: the optic nerve stump (ONS), the peripapillary (PP) sclera, and non-PP sclera. Results The PP scleral tensile strains were found to be lower for ED eyes compared with AD and HIS eyes at 15 mm Hg (P = 0.024 and 0.039, respectively). The mean compressive strains were significantly higher for AD eyes compared with ED eyes at 15 mm Hg (P = 0.018). We also found that the relationship between tensile strain and pressure was significant for those of ED and HIS eyes (P < 0.001 and P = 0.004, respectively), whereas it was not significant for those of AD (P = 0.392). Conclusions Our results suggest that, assuming glaucomatous nerve loss is caused by mechanical strains in the vicinity of the optic nerve head, the mechanism of increased glaucoma prevalence may be different in those of AD versus HIS. Our ONS strain analysis also suggested that it may be important to account for ONS geometry and material properties in future scleral biomechanical analysis.