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Preemptive scheduling in a two-stage flow shop with at least two identical parallel machines in one of the stages to minimize makespan is NP-hard in the strong sense. Johnson's efficient algorithm presented in 1954 for minimizing makespan in two-machine flow shop cannot be used for preemptive scheduling. McNaughton's wrap-around rule presented in 1959 calculates the shortest preemptive schedule on identical parallel machines in linear time but there is no similarly effective algorithm for the simplest common generalization of the problem.

We introduce the categorized reference database ORchestra, which is available online at http://www.utwente.nl/choir/orchestra/. [ABSTRACT FROM AUTHOR]

The growing biomedical challenges impose the continuous development of novel platforms. Ensuring the biocompatibility of drug delivery and implantable biomedical devices is an essential requirement. Calcium carbonate (CaCO3) in the form of vaterite nanoparticles is a promising platform, which has demonstrated distinctive optical and biochemical properties, including high porosity and metastability. In this study, the biocompatibility of differently shaped CaCO 3 vaterite particles (toroids, ellipsoids, and spheroids) are evaluated by bacterial toxicity mode-of-action with a whole-cell biosensor. Different Escherichia coli (E. coli) strains were used in the bioluminescent assay, including cytotoxicity, genotoxicity and quorum-sensing. Firstly, both scanning electron microscopy (SEM) and fluorescence microscopy characterizations were conducted. Bacterial cell death and aggregates were observed only in the highest tested concentration of the vaterite particles, especially in toroids 15-25 µm. After, the bioluminescent bacterial panel was exposed to the vaterite particles, and their bioluminescent signal reflected their toxicity mode-of-action. The vaterite particles resulted in an induction factor (IF > 1) on the bacterial panel, which was higher after exposure to the toroids (1.557 ≤ IF ≤ 2.271) and ellipsoids particles (1.712 ≤ IF ≤ 2.018), as compared to the spheroids particles (1.134 ≤ IF ≤ 1.494), in all the tested bacterial strains. Furthermore, the vaterite particles did not affect the viability of the bacterial cells. The bacterial monitoring demonstrated the biofriendly nature of especially spheroids vaterite nanoparticles., Competing Interests: Declaration of Competing Interest The authors declared no potential conflicts of interest concerning the research, authorship, and/or publication of this article., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The red palm weevil (RPW), Rhynchophorus ferrugineus, is considered a severe pest of palms. Usually, the early stages of infection are without visible signs. An attractive early sensing approach of non-visible infections is based on volatile organic compounds (VOCs). In this study, a whole-cell bacterial biosensor was used for the identification of RPW in date palm (Phoenix dactylifera). The cells are genetically modified to produce light in the presence of general stresses. The bioluminescent bacterial panel is based on three genetically engineered Escherichia coli strains that are sensitive to cytotoxicity (TV1061), genotoxicity (DPD2794), or quorum-sensing (K802NR). The bioluminescent bacterial panel detects the presence of VOCs and a change in the light signal is then generated, reflecting the health status of the date palm tree. The bioreporter bacteria cells are immobilized in calcium alginate tablets and placed in a sealed jar without direct contact with the tested sample, thereby exposing them only to the VOCs in the surrounding air. The immobilized bacteria cells were exposed to the air near infected by RPW or uninfected sugar canes, date palm tree pieces, and on date palm trees. Commercial plate reader was used for signal measurement. The findings show that quorum-sensing was induced by all the tested samples of infected sugar canes, date palm tree pieces, and date palm trees. While, cytotoxicity was induced only by infected date palm tree pieces, and genotoxicity was induced only by infected date palm trees. The bacterial monitoring results enable the identification of specific signatures that will allow a quick and accurate diagnosis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Half of the harvested food is lost due to rots caused by microorganisms. Plants emit various volatile organic compounds (VOCs) into their surrounding environment, and the VOC profiles of healthy crops are altered upon infection. In this study, a whole-cell bacterial biosensor was used for the early identification of potato tuber soft rot disease caused by the pectinolytic bacteria Pectobacterium in potato tubers. The detection is based on monitoring the luminescent responses of the bacteria panel to changes in the VOC profile following inoculation. First, gas chromatography-mass spectrometry (GC-MS) was used to specify the differences between the VOC patterns of the inoculated and non-inoculated potato tubers during early infection. Five VOCs were identified, 1-octanol, phenylethyl alcohol, 2-ethyl hexanol, nonanal, and 1-octen-3-ol. Then, the infection was detected by the bioreporter bacterial panel, firstly measured in a 96-well plate in solution, and then also tested in potato plugs and validated in whole tubers. Examination of the bacterial panel responses showed an extensive cytotoxic effect over the testing period, as seen by the elevated induction factor (IF) values in the bacterial strain TV1061 after exposure to both potato plugs and whole tubers. Moreover, quorum sensing influences were also observed by the elevated IF values in the bacterial strain K802NR. The developed whole-cell biosensor system based on bacterial detection will allow more efficient crop management during postharvest, storage, and transport of crops, to reduce food losses., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Biofilm formation by photosynthetic organisms is a complex behavior that serves multiple functions in the environment. Biofilm formation in the unicellular cyanobacterium Synechococcus elongatus PCC 7942 is regulated in part by a set of small secreted proteins that promotes biofilm formation and a self-suppression mechanism that prevents their expression. Little is known about the regulatory and structural components of the biofilms in PCC 7942, or response to the suppressor signal(s). We performed transcriptomics (RNA-Seq) and phenomics (RB-TnSeq) screens that identified four genes involved in biofilm formation and regulation, more than 25 additional candidates that may impact biofilm formation, and revealed the transcriptomic adaptation to the biofilm state. In so doing, we compared the effectiveness of these two approaches for gene discovery., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Simkovsky, Parnasa, Wang, Nagar, Zecharia, Suban, Yegorov, Veltman, Sendersky, Schwarz and Golden.)

Chitosan is a nature-sourced polysaccharide widely used in numerous applications. The antibacterial potential of chitosan has attracted researchers to further develop and utilize this polymer for the formation of biocompatible antibacterial agents for both the food and healthcare industries. The tested hypothesis in this study is that modified N-alkylaminated chitosan nanoparticles (CNPs) have selective binding properties to Gram-negative bacteria strains that result in bacterial aggregation. Various bacterial strains were tested of five Gram-negative bacteria including Erwinia carotovora, Escherichia coli, Pseudomonas aeruginosa, Salmonella, and Serratia marcescens, as well as three Gram-positive bacteria strains including Bacillus licheniformis, Bacillus megaterium, and Bacillus subtilis. The fluorescence microscopy characterization showed that the presence of CNPs caused the aggregation of Escherichia coli bacteria cells, where modified CNPs with a shorter chain length of the substituent caused a higher aggregation effect. Moreover, it was found that the CNPs exhibited a selective binding behavior to Gram-negative as compared to Gram-positive bacteria strains, mainly to Escherichia coli and Salmonella. Also, the scanning electron microscopy characterization showed that CNPs exhibited selective binding to Gram-negative bacteria, which was especially understood when both Gram-negative and Gram-positive bacteria strains were within the same sample. In addition, the bacterial viability assay suggests that CNPs with a lower degree of substitution have a higher inhibitory effect on bacterial growth. CNPs with longer side chains had a less inhibitory effect on the bacterial growth of Gram-negative strains, where a concentration-dependent response pattern was only seen for the cases of Gram-negative strains, and not for the case of Gram-positive strain. To conclude, the further understanding of the selective binding of CNPs to Gram-negative bacteria strains may produce new opportunities for the discovery and characterization of effective antibacterial agents., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The world acceptance of medical cannabis slowly widens. Cannabinoids are known as the main therapeutic active compounds in the cannabis plant, yet their bioactive physiological effects are still unknown. In this study, the mode of action of nine selected cannabinoids was examined using a bioluminescent bacterial panel, as well as the extracts of six different cannabis varieties and cannabinoids standards artificial mixtures. The bacterial panel was composed of genetically modified E. coli bacteria that is commonly found in the gut microbiome, to which a lux operon was added to various stress promoters. The panel was exposed to the cannabinoids in order to identify bacterial defense mechanism, via the aforementioned specific stress types response. This enables the understanding of the toxicity mode of action of cannabinoids. From all the tested cannabinoids, only delta-9-tetrahydrocannabinol (THC) and delta-9-tetrahydrocannabinolic acid A (THCA) produced a genotoxic effect, while the other tested cannabinoids, demonstrated cytotoxic or oxidative damages. Unlike pure cannabinoids, cannabis plant extracts exhibited mostly genotoxicity, with minor cytotoxicity or oxidative stress responses. Moreover, cannabinoids standards artificial mixtures produced a different response patterns compared to their individual effects, which may be due to additional synergistic or antagonistic reactions between the mixed chemicals on the bacterial panel. The results showed that despite the lack of cannabigerol (CBG), cannabidivarin (CBDV), cannabinol (CBN), and cannabichromene (CBC) in the artificial solution mimicking the CN6 cannabis variety, a similar response pattern to the cannabinoids standards mixture was obtained. This work contributes to the understanding of such correlations and may provide a realistic view of cannabinoid effects on the human microbiome., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Over the past two decades, whole-cell biosensors (WCBs) have been widely used in the environmental field, with only few applications proposed for use in agricultural. This study describes the development and optimization of a WCB for the detection of volatile organic compounds (VOCs) that is produced specifically by infected potato tubers. First, the effect of calcium-alginate matrix formation (beads vs. tablets) on the membrane uniformity and sensing efficiency was evaluated. Then, important parameters in the immobilization process were examined for their effect on the sensitivity to the presence of VOCs. The highest sensitivity to the target VOC was obtained by 20 min polymerization of bacterial suspension with optical density of 0.2 at 600 nm, dissolved in low-viscosity sodium alginate (1.5% w/v) and exposure to VOC at 4 °C. After optimization, the lowest limit of detection for three infection-sourced VOCs (nonanal, 3-methyl-1-butanol, and 1-octen-3-ol) was 0.17-, 2.03-, and 2.09-mg/L, respectively, and the sensor sensitivity was improved by 8.9-, 3.1- and 2-fold, respectively. Then, the new optimized immobilization protocol was implemented for the CMOS-based application, which increased the sensor sensitivity to VOC by 3-fold during real-time measurement. This is the first step in creating a sensor for real-time monitoring of crop quality by identifying changes in VOC patterns., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A series of stable polysaccharide derivatives that spontaneously self-assemble into nanocarriers was synthesized by applying a reductive amination on chitosan. The prepared nanocarriers were comprehensively studied and found to allow encapsulation of molecular cargo in both aqueous and lipidic media and deliver this cargo across biological barriers. The nanocarriers have demonstrated effective transdermal delivery of diclofenac (Voltaren), a nonsteroidal anti-inflammatory drug, by increasing its skin permeation up to 100 vs the tested control. The modified polysaccharides were studied with a panel of three types of bioreporter bacteria sensitive to genotoxic and cytotoxic stresses. These studies showed the general safety of the prepared nanocarriers and provided insights concerning their activity in collaboration with the aliphatic side chain length. The described nanocarriers could be applied as tunable biocompatible vehicles for the delivery of medicines, cosmetic agents, and in other applications.

Chlorination and ozonation of various waters may be associated with the formation of toxic disinfection byproducts (DBPs) and cause health risks to humans. Monitoring the toxicity of chlorinated and ozonated water and identification of different toxicity mechanisms are therefore required. This study is one of its kind to examine the toxic effects of chlorinated and ozonated wastewater effluents on three genetically modified bioluminescent bacteria, in comparison to the naturally isolated cyanobacteria, Spirulina strains as test systems. Three different secondary wastewater effluents were collected from treatment plants, chlorinated using sodium hypochlorite (at 1 and 10 mg L -1 of chlorine) or treated using 3-4 mg L -1 of ozone at different contact times. As compared to cyanobacterial Spirulina sp., the genetically modified bacteria enhancing bioluminescence at the presence of stress agents demonstrated greater sensitivity to the toxicity induction and have also provided mechanism-specific responses associated with genotoxicity, cytotoxicity and reactive oxygen species (ROS) generation in wastewater effluents. Effects of effluent chlorination time and chlorine concentration revealed by means of bioluminescent bacteria suggest the formation of genotoxic and cytotoxic DBPs followed with their possible disappearance at longer times. Ozonation could degrade genotoxic compounds in some effluents, but the cytotoxic potential of wastewater effluents may certainly increase with ozonation time. No induction of ROS-related toxicity was detected in either chlorinated or ozonated wastewater effluents. UV absorbance- and fluorescence emission-based spectroscopic characteristics may be variously correlated with changes in genotoxicity in ozonated effluents, however, no associations were obtained in chlorinated wastewater effluents. The bacterial response to the developed mechanism-specific toxicity differs among wastewater effluents, reflecting variability in effluent compositions., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

We propose a mathematical programming formulation that incorporates annualized hours and shows to be very flexible with regard to modeling various contract types. The objective of our model is to minimize salary cost, thereby covering workforce demand, and using annualized hours. Our model is able to address various business questions regarding tactical workforce planning problems, e.g., with regard to annualized hours, subcontracting, and vacation planning. In a case study for a Dutch hospital two of these business questions are addressed, and we demonstrate that applying annualized hours potentially saves up to 5.2% in personnel wages annually.

A multiplex technique is described that can be used in photoelectric observations of dispersed spectra. The encoding pattern is a set of pseudo-random binary sequences. The data processing requires a minimum possible number of operations. A special purpose device could give the spectral intensity distribution on-line. An application at the solar eclipse (Mexico, 1970) is described.