Quality-by-design-based microemulsion of disulfiram for repurposing in melanoma and breast cancer therapy.

Aim: The current study aims to develop and optimize microemulsions (ME) through Quality-by-Design (QbD) approach to improve the aqueous solubility and dissolution of poorly water-soluble drug disulfiram (DSF) for repurposing in melanoma and breast cancer therapy. Materials & methods: The ME was formulated using Cinnamon oil & Tween® 80, statistically optimized using a D-optimal mixture design-based QbD approach to develop the best ME with low vesicular size (Zavg) and polydispersity index (PDI). Results: The DSF-loaded optimized stable ME showed enhanced dissolution, in-vitro cytotoxicity and improved cellular uptake in B16F10 and MCF-7 cell lines compared with their unformulated free DSF. Conclusion: Our investigations suggested the potential of the statistically designed DSF-loaded optimized ME for repurposing melanoma and breast cancer therapy.

Identifying new medicinal uses of an existing marketed drug can save both money and time in the process of drug development. From many of the recently reported literature, disulfiram (a drug used for alcoholism) has shown its activity against various cancers, including breast and skin cancer. However, it possesses poor water solubility and absorption, leading to low medicinal activity. The current study aims to develop a novel microemulsion dosage form through a statistical design approach to enhance the solubility, dissolution and anticancer activity for repurposing in melanoma and breast cancer treatment. The novel microemulsion was prepared, statistically analyzed and optimized. The optimized microemulsion was found to be stable and showed improved medicinal activity against breast and skin cancer compared with the pure drug. Our research showed the potential of the developed microemulsion of the disulfiram for its new therapeutic use in skin cancer and breast cancer.

D-optimal Design Optimization of Solvent Mixture for Flavonoid Extraction from Phalaenopsis Leaves with Antioxidant Activity.

Aims: This study aimed to optimize the extraction of flavonoids and antioxidants from Phalaenopsis leaves by using solvent mixtures. Method: The total flavonoid content (TFC) and antioxidant activity were evaluated using the colorimetric method and ferric-reducing antioxidant power (FRAP), respectively. Maceration extracts from fresh leaves were used for the analysis. The study used the Design Expert 13.0 program to optimize the solvents (water, acetone, and methanol) and their combined ratio. Result: The results showed that 100% acetone was the best solvent for both responses, with a desirability value of 0.884, TFC of 0.434 mg QE/g fresh weight (FW) and FRAP of 713.53 µmol TE/g FW. Screening of the most potent Phalaenopsis genotypes for obtaining the most active leaf extract showed that P. amboinensis and P. pantherina were the best genotypes for TFC (0.786-0.797 mg QE/g FW) and FRAP activity (862.25-891.48 µmol TE/g FW). Conclusion: This study demonstrates an easy and useful way to obtain flavonoids and antioxidants from Phalaenopsis materials that can be used in the flower-based industry to make new functional ingredients.

Metformin Loaded Zein Polymeric Nanoparticles to Augment Antitumor Activity against Ehrlich Carcinoma via Activation of AMPK Pathway: D-Optimal Design Optimization, In Vitro Characterization, and In Vivo Study.

Metformin (MET), an antidiabetic drug, is emerging as a promising anticancer agent. This study was initiated to investigate the antitumor effects and potential molecular targets of MET in mice bearing solid Ehrlich carcinoma (SEC) as a model of breast cancer (BC) and to explore the potential of zein nanoparticles (ZNs) as a carrier for improving the anticancer effect of MET. ZNs were fabricated through ethanol injection followed by probe sonication method. The optimum ZN formulation (ZN8) was spherical and contained 5 mg zein and 30 mg sodium deoxycholate with a small particle size and high entrapment efficiency percentage and zeta potential. A stability study showed that ZN8 was stable for up to three months. In vitro release profiles proved the sustained effect of ZN8 compared to the MET solution. Treatment of SEC-bearing mice with ZN8 produced a more pronounced anticancer effect which was mediated by upregulation of P53 and miRNA-543 as well as downregulation of NF-κB and miRNA-191-5p gene expression. Furthermore, ZN8 produced a marked elevation in pAMPK and caspase-3 levels as well as a significant decrease in cyclin D1, COX-2, and PGE2 levels. The acquired findings verified the potency of MET-loaded ZNs as a treatment approach for BC.

Enhancing basil essential oil microencapsulation using pectin/casein biopolymers: Optimization through D-optimal design, controlled release modeling, and characterization.

A D-optimal design was employed to optimize the microencapsulation (MEC) of basil essential oil (BEO) within a biopolymer matrix using the complex coacervation technique. BEO microcapsules (BEO-MCs) obtained under the optimal conditions exhibited high yield and efficiency with 80.45 ± 0.01 % and 93.10 ± 0.18 %, respectively. The successful MEC of BEO with an average particle size of 4.81 ± 2.86 µm was confirmed by ATR-FTIR, X-RD, and SEM analyses. Furthermore, the thermal stability of BEO-MCs was assessed using TGA-DSC analysis, which provided valuable insights into the MC's thermal stability. Furthermore, the proposed model, with a high R2 value (0.99) and low RMSE (1.56 %), was the most suitable one among the tested models for the controlled release kinetics of the optimal BEO-MCs under simulated gastrointestinal conditions. The successful optimization of BEO MEC using biopolymers through the D-optimal design could be a promising avenue for food and pharmaceutical industries, providing new strategies for the development of effective products.

Impact of pH on physicochemical properties of corn starch by dry heat treatment.

This study investigated the effects of temperature, pH, and starch genotype on starch characteristics after dry heat treatment (DHT). DHT starches were prepared according to 19 DHT conditions, constructed using a D-optimal design, and analyzed with respect to apparent amylose (AAM) content, X-ray diffraction (XRD) pattern, relative crystallinity (RC), solubility and swelling power (SP), thermal properties, and pasting viscosity. The DHT starches maintained their granular structures even after DHT at pH 3, although there was some damage to their granular surfaces. The DHT starches showed lower amylose content, RC, SP, gelatinization temperature and enthalpy, degree of retrogradation, and pasting viscosity, but higher solubility, compared to those of native starches. These DHT effects were more pronounced as pH decreased at each temperature, regardless of the starch genotype. Overall, DHT can be used to expand the physical functionality of high-amylose and highly crystallized starches with poor properties. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01353-7.

The Gelatin-Coated Nanostructured Lipid Carrier (NLC) Containing Salvia officinalis Extract: Optimization by Combined D-Optimal Design and Its Application to Improve the Quality Parameters of Beef Burger.

The current study aims to synthesize the gelatin-coated nanostructured lipid carrier (NLC) to encapsulate sage extract and use this nanoparticle to increase the quality parameters of beef burger samples. NLCs were prepared by formulation of gelatin (as surfactant and coating biopolymer), tallow oil (as solid lipid), rosemary essential oil (as liquid lipid), sage extract (as active material or encapsulant), polyglycerol ester and Tween 80 (as low-molecular emulsifier) through the high-shear homogenization-sonication method. The effects of gelatin concentrations and the solid/liquid ratio on the particle size, polydispersity index (PDI), and encapsulation efficiency (EE%) of sage extract-loaded NLCs were quantitatively investigated and optimized using a combined D-optimal design. Design expert software suggested the optimum formulation with a gelatin concentration of 0.1 g/g suspension and solid/liquid lipid ratio of 60/40 with a particle size of 100.4 nm, PDI of 0.36, and EE% 80%. The morphology, interactions, thermal properties, and crystallinity of obtained NLC formulations were investigated by TEM, FTIR, DSC, and XRD techniques. The optimum sage extract-loaded/gelatin-coated NLC showed significantly higher antioxidant activity than free extract after 30 days of storage. It also indicated a higher inhibitory effect against E. coli and P. aeruginosa than free form in MIC and MBC tests. The optimum sage extract-loaded/gelatin-coated NLC, more than free extract, increased the oxidation stability of the treated beef burger samples during 90 days of storage at 4 and -18 °C (verified by thiobarbituric acid and peroxide values tests). Incorporation of the optimum NLC to beef burgers also effectively decreased total counts of mesophilic bacteria, psychotropic bacteria, S. aureus, coliform, E. coli, molds, and yeasts of treated beef burger samples during 0, 3, and 7 days of storage in comparison to the control sample. These results suggested that the obtained sage extract-loaded NLC can be an effective preservative to extend the shelf life of beef burgers.

Partial Least Squares, Experimental Design, and Near-Infrared Spectrophotometry for the Remote Quantification of Nitric Acid Concentration and Temperature.

Near-infrared spectrophotometry and partial least squares regression (PLSR) were evaluated to create a pleasantly simple yet effective approach for measuring HNO3 concentration with varying temperature levels. A training set, which covered HNO3 concentrations (0.1-8 M) and temperature (10-40 °C), was selected using a D-optimal design to minimize the number of samples required in the calibration set for PLSR analysis. The top D-optimal-selected PLSR models had root mean squared error of prediction values of 1.4% for HNO3 and 4.0% for temperature. The PLSR models built from spectra collected on static samples were validated against flow tests including HNO3 concentration and temperature gradients to test abnormal conditions (e.g., bubbles) and the model performance between sample points in the factor space. Based on cross-validation and prediction modeling statistics, the designed near-infrared absorption approach can provide remote, quantitative analysis of HNO3 concentration and temperature for production-oriented applications in facilities where laser safety challenges would inhibit the implementation of other optical techniques (e.g., Raman spectroscopy) and in which space, time, and/or resources are constrained. The experimental design approach effectively minimized the number of samples in the training set and maintained or improved PLSR model performance, which makes the described chemometric approach more amenable to nuclear field applications.

Travoprost Liquid Nanocrystals: An Innovative Armamentarium for Effective Glaucoma Therapy.

To date, the ophthalmic application of liquid crystalline nanostructures (LCNs) has not been thoroughly reconnoitered, yet they have been extensively used. LCNs are primarily made up of glyceryl monooleate (GMO) or phytantriol as a lipid, a stabilizing agent, and a penetration enhancer (PE). For optimization, the D-optimal design was exploited. A characterization using TEM and XRPD was conducted. Optimized LCNs were loaded with the anti-glaucoma drug Travoprost (TRAVO). Ex vivo permeation across the cornea, in vivo pharmacokinetics, and pharmacodynamic studies were performed along with ocular tolerability examinations. Optimized LCNs are constituted of GMO, Tween® 80 as a stabilizer, and either oleic acid or Captex® 8000 as PE at 25 mg each. TRAVO-LNCs, F-1-L and F-3-L, showed particle sizes of 216.20 ± 6.12 and 129.40 ± 11.73 nm, with EE% of 85.30 ± 4.29 and 82.54 ± 7.65%, respectively, revealing the highest drug permeation parameters. The bioavailability of both attained 106.1% and 322.82%, respectively, relative to the market product TRAVATAN®. They exhibited respective intraocular pressure reductions lasting for 48 and 72 h, compared to 36 h for TRAVATAN®. All LCNs exhibited no evidence of ocular injury in comparison to the control eye. The findings revealed the competence of TRAVO-tailored LCNs in glaucoma treatment and suggested the potential application of a novel platform in ocular delivery.

Design of mirtazapine solid dispersion with different carriers' systems: optimization, in vitro evaluation, and bioavailability assessment.

The solid dispersion technique is the most effective and widely used approach for increasing the solubility and release of drugs that have low water solubility. Mirtazapine (MRT) is an atypical antidepressant used to treat severe depression. MRT has a low oral bioavailability (about 50%) due to its low water solubility (BCS class II). The study's goal was to determine optimum conditions for incorporating MRT into various polymer types utilizing the solid dispersion (SD) technique, with the goal of selecting the most suitable formula with the optimal aqueous solubility, loading efficiency, and dissolution rate. The D-optimal design was used to pick the optimal response. The optimum formula was subjected to physicochemical evaluation by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM). In vivo bioavailability study was conducted on white rabbits' plasma samples. MRT-SDs were prepared by the solvent evaporation method using Eudragit (RL-100, RS-100, E-100, L-100-55), PVP K-30, and PEG 4000 with different drug/polymer percentages (33.33%, 49.99%, and 66.66%). Results showed that the optimum formula obtained using PVP K-30 at a drug percentage of 33.33% gave a loading efficiency of 100.93%, an aqueous solubility of 0.145 mg/ml, and a dissolution rate of 98.12% after 30 min. These findings demonstrated promising enhancement of MRT properties and increasing its oral bioavailability by 1.34-fold more than plain drug.

Ultra-high-performance supercritical fluid chromatography-mass spectrometry for the analysis of organic contaminants in sediments.

A nontarget screening method was developed based on D-optimal designs for ultra-high performance supercritical fluid chromatography with positive and negative electrospray ionization mode mass spectrometry. A mixture of organic contaminants such as pesticides, steroids, surfactants, phenolic and fatty acids, and polycyclic aromatic hydrocarbon derivatives, was used for the optimization. An aprotic mixture of dichloromethane and acetone [3:1] performed overall best as the injection solvent. The highest peak capacities (n) were accomplished at the shallowest gradient (1%B/min), ammonium formate (n = 378 in negative ionization mode), or ammonium acetate (n = 327 in positive ionization mode) in methanol as the modifier. Capillary voltage, make-up solvent flow rate, water, and additive concentration were the most significant factors for improving peak intensity: higher peak intensities were obtained at lower additive concentrations (5mM ammonium formate), and with 5% water in positive ionization mode. Conversely, water had detrimental effects in negative ionization mode. The optimized method was used to quantify organic contaminants in 17 freshwater sediment samples from Copenhagen, Denmark. Out of 50 monitored contaminants, 35 were detected in at least one sample. Further, the method has a potential for target and nontarget screening analysis of organic contaminants in solid matrices.

Optimization and In Vitro Digestion of a Guava (Psidium guajava), Mamey (Pouteria sapota) and Stevia (Stevia rebaudiana) Functional Beverage.

Guava and mamey are phenolic- and carotenoid-rich fruits with potential health benefits, but are minimally used as ingredients in functional beverages. The objectives of the present work are to optimize the content of guava and mamey pulps and a stevia solution in the formulation of a functional beverage with high content of bioactive compounds and sensory acceptability using a mixture design analysis, and to analyze its composition after in vitro digestion. The optimized formulation (17.77 and 19.23 g of guava and mamey pulps, respectively; 1% stevia solution) yielded a beverage with 418.21 mg gallic acid equivalents (GAE)/100 mL and 0.20 mg ß-carotene/100 mL, and an antioxidant capacity of 213.58, 78.90 and 234.03 mg Trolox equivalents (TE)/100 mL using three methodologies. The mathematical model developed was significant (p < 0.05), according to R2 values between 0.70 and 0.75. α- and ß-carotene were quantified during the oral phase of in vitro digestion. Gallic, p-coumaric, ferulic and chlorogenic acids were also identified. The beverage had a general acceptability of 6.72. We conclude that the mathematical model developed was a good predictor of the experimental data and that the optimized beverage contained high bioactive concentrations (phenolics and carotenoids) and was well-accepted by potential consumers.

Spanlastics as a Potential Platform for Enhancing the Brain Delivery of Flibanserin: In Vitro Response-Surface Optimization and In Vivo Pharmacokinetics Assessment.

Flibanserin was licensed by the United States Food and Drug Administration (FDA) as an oral non-hormonal therapy for pre-menopausal women with inhibited sexual desire disorder. However, it suffers from susceptibility to first-pass metabolism in the liver, low aqueous solubility, and degradation in the acidic stomach environment. Such hurdles result in a limited oral bioavailability of 33%. Thus, the aim of the study was to utilize the principles of nanotechnology and the benefits of an intranasal route of administration to develop a formulation that could bypass these drawbacks. A response-surface randomized D-optimal strategy was used for the formulation of flibanserin spanlastics (SPLs) with reduced size and increased absolute zeta potential. Two numerical factors were studied, namely the Span 60: edge activator ratio (w/w) and sonication time (min), in addition to one categorical factor that deals with the type of edge activator. Particle size (nm) and zeta potential (mV) were studied as responses. A mathematical optimization method was implemented for predicting the optimized levels of the variables. The optimized formulation was prepared using a Span: sodium deoxycholate ratio of 8:2 w/w; a sonication time of 5 min showed particle sizes of 129.70 nm and a zeta potential of -33.17 mV. Further in vivo assessment following intranasal administration in rats showed boosted plasma and brain levels, with 2.11- and 2.23-fold increases (respectively) compared to raw FLB. The aforementioned results imply that the proposed spanlastics could be regarded as efficient drug carriers for the trans-nasal delivery of drugs to the brain.

Optimal designs for health risk assessments using fractional polynomial models.

Fractional polynomials (FP) have been shown to be more flexible than polynomial models for fitting data from an univariate regression model with a continuous outcome but design issues for FP models have lagged. We focus on FPs with a single variable and construct D-optimal designs for estimating model parameters and I-optimal designs for prediction over a user-specified region of the design space. Some analytic results are given, along with a discussion on model uncertainty. In addition, we provide an applet to facilitate users find tailor made optimal designs for their problems. As applications, we construct optimal designs for three studies that used FPs to model risk assessments of (a) testosterone levels from magnesium accumulation in certain areas of the brains in songbirds, (b) rats subject to exposure of different chemicals, and (c) hormetic effects due to small toxic exposure. In each case, we elaborate the benefits of having an optimal design in terms of cost and quality of the statistical inference.

Sertaconazole-Nitrate-Loaded Leciplex for Treating Keratomycosis: Optimization Using D-Optimal Design and In Vitro, Ex Vivo, and In Vivo Studies.

This study aims to develop efficient topical therapy for keratomycosis using sertaconazolenitrate (STZN)-loaded leciplex (LP). The D-optimal design was used to optimize STZN-loaded LP by utilizing soy phosphatidylcholine (SPC) molar ratio (X1), cationic surfactant molar ratio (X2), and cationic surfactant type (X3) as the independent variables, whereas their impact was studied for entrapment efficiency percent (EE; Y1), particle size (PS; Y2), polydispersity index (PDI; Y3), zeta potential (ZP; Y4), and permeability coefficient (Kp; Y5). The optimized formula was evaluated regarding morphology, ex vivo permeation, mucoadhesion, stability, and in vivo studies. The optimized formula was spherical and showed EE of 84.87 ± 1.71%, PS of 39.70 ± 1.35 nm, PDI of 0.242 ± 0.006, ZP of +54.60 ± 0.24 mV, and Kp of 0.0577 ± 0.0001 cm/h. The ex vivo permeation study revealed that the optimized formula enhanced the Kp and corneal deposition by 2.78 and 12.49 folds, respectively, compared to the aqueous drug dispersion. Furthermore, the optimized formula was stable and revealed promising mucoadhesion properties. Finally, the in vivo studies showed that the optimized formula was superior to the drug dispersion in treating rats with induced keratomycosis. These results confirmed the capabilities of LP as a promising nanocarrier for treating ocular diseases topically.

Implementation of a Design of Experiments to Improve Periplasmic Yield of Functional ScFv Antibodies in a Phage Display Platform.

Purpose: Production of functional recombinant antibody fragments in the periplasm of E. coli is a prerequisite step to achieve sufficient reagent for preclinical studies. Thus, the cost-effective and lab-scale production of antibody fragments demands the optimization of culture conditions. Methods: The culture conditions such as temperature, optical density (OD600) at induction, induction time, and IPTG concentration were investigated to optimize the functional expression of a phage-derived scFv molecule using a design of experiment (DoE). Additionally, the effects of different culture media and osmolyte supplements on the expression yield of scFv were examined. Results: The developed 2FI regression model indicated the significant linear effect of the incubation temperature, the induction time, and the induction OD600 on the expression yield of functional scFv. Besides, the statistical analysis indicated that two significant interactions of the temperature/induction time and the temperature/induction OD600 significantly interplay to increase the yield. Further optimization showed that the expression level of functional scFv was the most optimal when the cultivation was undertaken either in the TB medium or in the presence of media supplements of 0.5 M sorbitol or 100 mM glycine betaine. Conclusion: In the present study, for the first time, we successfully implemented DoE to comprehensively optimize the culture conditions for the expression of scFv molecules in a phage antibody display setting, where scFv molecules can be isolated from a tailor-made phage antibody library known as "Human Single Fold scFv Library I."

Augmented in vitro and in vivo Profiles of Brimonidine Tartrate Using Gelatinized-Core Liposomes.

Background: The low entrapment efficiency of the hydrophilic drugs such as brimonidine tartrate (BRT) in liposomes represents a challenge that requires interventions. Gelatinized core liposomes (GCLs) were fabricated to increase the drug entrapment, corneal penetration, and physical stability of the investigated molecule. Research Design and Methods: GCLs encapsulating BRT were prepared and optimized utilizing D-optimal design (DOD). The effect of plasticizer incorporation on the physicochemical characteristics and on the in vivo performance was studied. The optimized formulations were investigated for pH, rheological properties, morphological characteristics, in vitro release profiles, biological performance, safety profile. The effects of storage and gamma sterilization were also investigated. Results: The results revealed the great success of the prepared formulations to achieve high entrapment efficiency reaching 98% after a maturation period of 10 days. The addition of glycerol as plasticizer significantly minimized the particle size and shortened the maturation period to 7 days. The selected formulations were stable for 3 months after gamma sterilization. The formulations showed significant lowering of intra-ocular pressure (IOP) in glaucomatous rabbits with sustainment of the pharmacological effect for 24 hours compared to drug solution. Conclusions: Enhanced in vitro and in vivo profiles of brimonidine tartrate loaded gelatinized-core-liposomes were obtained.

Hyaluronic acid-enriched bilosomes: an approach to enhance ocular delivery of agomelatine via D-optimal design: formulation, in vitro characterization, and in vivo pharmacodynamic evaluation in rabbits.

Agomelatine (AGO) is a dual-functional drug. It uses as an antidepressant when orally administrated and antiglaucomic when topically applied to the eye. This study aimed to formulate AGO into bilosomal vesicles for glaucoma treatment, as modern studies pointed out the effect of topical AGO on intraocular pressure for the treatment of glaucoma. A modified ethanol injection technique was used for the fabrication of AGO bilosomes according to a D-optimal design. Phosphatidylcholine (PC) to edge activator (EA) ratio, Hyaluronic acid percentage (HA%), and EA type were utilized as independent variables. The measured responses were percent entrapment efficiency (EE%), particle size (PS), polydispersity index, zeta potential, percentage of drug released after 2 h (Q2h%), and 24 h (Q24h%). The optimal bilosomal formula (OB), with the desirability of 0.814 and the composition of 2:1 PC: EA ratio, 0.26% w/v HA and sodium cholate as EA, was subjected to further in vitro characterizations and in vivo evaluation studies. The OB formula had EE% of 81.81 ± 0.23%, PS of 432.45 ± 0.85 nm, Q2h% of 42.65 ± 0.52%, and Q24h% of 75.14 ± 0.39%. It demonstrated a higher elasticity than their corresponding niosomes with a typical spherical shape of niosomes by using transmission electron microscope. It exhibited acceptable stability over three months. pH and Refractive index measurements together with the histopathological study ensured that the OB formula is safe for the eye and causes no ocular irritation or blurred vision. The OB formula showed superiority in the in vivo pharmacodynamics parameters over the AGO solution, so AGO-loaded bilosome could improve ocular delivery and the bioavailability of agomelatine.

Intranasally administered melatonin core-shell polymeric nanocapsules: A promising treatment modality for cerebral ischemia.

AIMS: The neurohormone melatonin (MEL) has been reported as a promising neuroprotective molecule, however it suffers pharmaceutical limitations such as poor solubility and low bioavailability, which hinder its pharmacological and clinical potential. In the current work, MEL was loaded in core-shell nanocarrier system; polymeric nanocapsules (PNCs), and assessed for its potential in cerebral ischemia reperfusion injury rat model when administered intranasally. KEY FINDINGS: Adopting a D-optimal factorial design, MEL-PNCs were successfully formulated using the nanoprecipitation technique. MEL-PNCs exhibited a particle size ranging from 143.5 to 444 nm, negative zeta potential values ranging from -24.2 to -38.7 mV, cumulative release % for MEL ranging from 36.79 to 41.31 % over 8 h period, with overall good storage properties. The selected MEL-PNCs formulation displayed 8-fold higher permeation than the drug solution across sheep nasal mucosa. MEL-PNCs administered intranasally decreased oxidative stress and hippocampal inflammation, and the histological examination revealed the significant restoration of hippocampal neurons. SIGNIFICANCE: MEL-PNCs administered intranasally could be a promising treatment modality in brain ischemia.

Experimental Validation of Entropy-Driven Swarm Exploration under Sparsity Constraints with Sparse Bayesian Learning.

Increasing the autonomy of multi-agent systems or swarms for exploration missions requires tools for efficient information gathering. This work studies this problem from theoretical and experimental perspectives and evaluates an exploration system for multiple ground robots that cooperatively explore a stationary spatial process. For the distributed model, two conceptually different distribution paradigms are considered. The exploration is based on fusing distributively gathered information using Sparse Bayesian Learning (SBL), which permits representing the spatial process in a compressed manner and thus reduces the model complexity and communication load required for the exploration. An entropy-based exploration criterion is formulated to guide the agents. This criterion uses an estimation of a covariance matrix of the model parameters, which is then quantitatively characterized using a D-optimality criterion. The new sampling locations for the agents are then selected to minimize this criterion. To this end, a distributed optimization of the D-optimality criterion is derived. The proposed entropy-driven exploration is then presented from a system perspective and validated in laboratory experiments with two ground robots. The experiments show that SBL together with the distributed entropy-driven exploration is real-time capable and leads to a better performance with respect to time and accuracy compared with similar state-of-the-art algorithms.

D-optimal design of the additive mixture model with multi-response.

This paper proposes the D-optimal design for the additive mixture model with two-response, which is linear model with no interaction terms. The optimality was validated by using the general equivalence theorem, and the corresponding weights are found under which additive model satisfies D-optimality. In addition, relevant statistics and graphics are given to illustrate our results.