Single Carrier Research Articles

Deep blue fluorescent emitters based imidazole and carbazole for non-doped organic light emitting diodes with CIEy≤0.05

Two fluorescent emitters based imidazole and carbazole were synthesized for deep blue emission organic light-emitting diodes (OLED) with non-doped structure. The photophysical, thermal and electrochemical properties are investigated with high decomposition temperature up to 391 and 380 °C, and strong deep blue emission. Single carrier devices were also fabricated to show that two compounds have good bipolar carrier transport characteristic. The non-doped fluorescent OLED devices using the two compounds as emitting layers are designed among which the devices achieved the maximum external quantum efficiency of 1.66% and 1.56%, respectively. Besides, the deep blue emission peak of 412 nm with Commission Internationale de l’Eclairage (CIE) coordinate of (0.16, 0.04), and 420 nm with CIE coordinate of (0.16, 0.05) were also realized. The small CIEy value of 0.04 and 0.05 obtained in this work are very significant for high color purity full-color display, which is also among the best CIEy value results ever reported as deep blue bipolar emitters.

Trapezoidal reference-based single carrier pulse width modulation method for multilevel converters with novel FPGA implementation

Recent attention has focused on trapezoidal reference-based pulse width modulation (PWM) schemes in multilevel converters (MLCs) with easier implementation and better harmonic performance. Nevertheless, these studies utilize trapezoidal reference only for multi carrier PWM methods and details of FPGA implementation are not provided. This paper proposes a trapezoidal reference-based single carrier PWM (TSC-PWM) with its novel FPGA implementation. Design parameters of TSC-PWM is determined such that harmonic performance is maximized and architectural details of FPGA implementation of TSC-PWM are provided. Results reveal that TSC-PWM significantly reduces the resource utilization compared to other methods. Single-phase three-module cascaded H-bridge MLC (CHB-MLC) is established in both simulation and experimental platforms. Results indicate that the TSC-PWM provides better harmonic performance along with higher DC utilization ratio compared to other methods. Moreover, both half-wave and quarter-wave symmetries are ensured with TSC-PWM.

Single-Carrier, Single-λ Full-Duplex Analog Radio Feed Over a Single-Port RRH Transceiver

The densification of radio access and the massive deployment of radio heads calls for efficient optical fronthaul technologies. The adoption of analogue radio-over-fiber schemes promises greatly simplified equipment that can be distributed at the antenna sites for the purpose of radio signal conditioning and electro-optic conversion. Towards this direction, we propose and experimentally evaluate a full-duplex interface at the intersection between the optical and the radio frequency layer, aiming at bidirectional radio signal transmission over a single wavelength (1577 nm) and a single carrier frequency (5.375 GHz). Analogue coherent optical reception is performed through an electro-absorption modulated laser, which is employed as multi-functional element that accomplishes wavelength re-use for full-duplex radio-over-fiber transmission. The directional split is shifted to the electrical domain through adoption of a crosstalk-cancelling circulation stage, ensuring compatibility with a high dynamic power range for the simultaneous transmission and reception of up- and downlink radio signals, respectively, without the need for further duplexing methods subject to frequency translation or time slotting. We prove that margins of >2% in terms of error vector magnitude can be accomplished for an unpaired spectral configuration, where down- and uplink radio signals share the same spectrum in the optical and electrical domains.

An assessment of advanced DC-link based reversing voltage type multilevel inverter topologies

AbstractIn this paper, advanced DC-Link (DCL) based reversing voltage type Multilevel Inverter (MLI) topologies by compensating the difficulties in the conventional MLIs are reviewed. These topologies consist of less switching components and driver circuits when compared with conventional MLIs predominantly in higher levels. Consequently, installation area, total cost and hardware difficulties are reduced by increasing the voltage levels. The unipolar based Pulse Width Modulation Schemes (PWMS) will improve DCL inverters performance. This paper presents unipolar Multi-Reference (MR) based sine and space vector PWMS with single triangular carrier wave for generating required levels in output voltage. Comparison between UMR sine and space vector PWMS for DCL inverter topologies is presented in terms of Fundamental Output Voltage (FOV) and Total Harmonic Distortion (THD). The research tries to establish the survey analysis for single-phase 7-level DCL based reversing voltage type MLI topologies with UMR based sine and space vector PWMs. Finally, to confirm the feasibility of proposed DCL-MLIs in terms of FOV and THD the simulation results are incorporated. Further, the prototype model is developed for single-phase 7-level DCL inverter with Field Programmable Gate Array (FPGA) based UMR sine and space vector PWMS to authenticate simulation results. The efficiency of the proposed cascaded MLI achieves the value of 99.003%.

Vesosomal drug delivery system with multi-compartments for controlled and sustained release

Liposomes are spherical structures enveloped by a lipid bilayer. They have been extensively studied to date due to their advantage of self-assembly, biocompatibility, good cellular/tissue uptake, and capability to carry large drug payloads. On the other hand, limitations still remain in multi-drug loading in a single carrier and controlling their release. On-demand drug release is a desirable feature in drug delivery systems to have more precise control over drug release, resulting in the reduction of drug payloads for safer and more economical medication. Light-triggered drug release systems have their benefits in being non-invasive, tissue-penetrable, and target-specific. However, most of proposed systems have not been realized for approved treatments because of the necessity of continuous light exposure, inability to meet an optimal cutoff size, and molecular interruptions. Herein, we devised a drug delivery system enabling the light-triggered sequential release of drugs through a multicompartment vesosomal system, in which smaller liposomes were encapsulated in a larger unilamellar vesicle. The lipid peroxidation of lipids in the liposomal form upon red-light-induced reactive oxygen species (ROS) caused the liposomes to release encapsulated contents. Liposomes composed of different unsaturated/saturated lipid fractions along with a photosensitizer were loaded into a vesosomal system. Upon light exposure, ROS-vulnerable liposomes release their contents while the contents in ROS-non-vulnerable were released after some delay. This system was further investigated in vitro with calcein-loaded vesosomes and doxorubicin-loaded vesosomes for demonstrating the controlled and sustained release of contents, respectively. Moreover, Caenorhabditis elegans was tested as an in vivo model due to its similarity of the epidermis layer to the human skin and showed inhibited growth in the red-light-exposed group. Through this work, we believe that our work could pave a road for intelligent multicompartmental drug delivery systems, enabling on-demand drug delivery.

A Five-Leg Three-Level Dual-Output Inverter

Classical 3-level dual-output inverter, 3-L DOI, involves two similar 3-level inverters that provides a pair of 3-phase output voltages with same or different frequencies from common input voltage source. Flexibility of either operation of the constituting inverters is evident in this DOI; but total duplication of power switches is a major drawback. State of the art coupled 3-L DOIs reduce this drawback by providing series-shared power devices between the two different 3-phase output terminals. Compared with the classical 3-L DOI, these newly developed coupled 3-L DOIs involves a smaller number of power switches; however, independent operation of the constituting inverters is lost. In this brief, a 3-L DOI is proposed which involves lesser number of power devices and provides flexibility of either operation of the constituting inverters. The 3-L DOI feature hinges on the concept of parallel-common-inverter-leg representation. At the same or varying frequency mode operation, the proposed inverter can synthesize two 3-phase output voltages. Range and relation between the two modes of operations are defined for the DOI. The control strategy is based on the single triangular carrier sinusoidal pulse-width modulation perspective. Experimental results are presented that depict the DOI inverter performances.

New insight into gain suppression and single event Burnout effects in LGAD

Low Gain Avalanche Detectors (LGADs) will be employed in the CMS MTD and ATLAS HGTD upgrades to mitigate the high levels of pile-up events expected in the High Luminosity phase of the LHC. Over the last several years, much attention has been focused on designing radiation-tolerant gain implants to ensure that these sensors survive the expected fluence (>1015 neq/cm2). This work reports several effects observed during our previous studies on two relevant phenomena Single Event Burnout (SEB) and carrier density-induced Gain Suppression (GS). Influence of irradiation level, pad configuration and gain layer depth on SEB are discussed. In this paper, we also extend GS study with a new insight into the spatio-temporal dynamics of charge transport in LGAD, probed with a focused ion beam.

Evaluation of High-Deductible Health Plans and Acute Glycemic Complications Among Adults With Diabetes

Optimal diabetes care requires regular monitoring and care to maintain glycemic control. How high-deductible health plans (HDHPs), which reduce overall spending but may impede care by increasing out-of-pocket expenses, are associated with risks of severe hypoglycemia and hyperglycemia is unknown. To examine the association between an employer-forced switch to HDHP and severe hypoglycemia and hyperglycemia. This retrospective cohort study used deidentified administrative claims data for privately insured adults with diabetes from a single insurance carrier with multiple plans across the US between January 1, 2010, and December 31, 2018. Analyses were conducted between May 15, 2020, and November 3, 2022. Patients with 1 baseline year of enrollment in a non-HDHP whose employers subsequently forced a switch to an HDHP were compared with patients who did not switch. Mixed-effects logistic regression models were used to examine the association between switching to an HDHP and the odds of severe hypoglycemia and hyperglycemia (ascertained using diagnosis codes in emergency department [ED] visits and hospitalizations), adjusting for patient age, sex, race and ethnicity, region, income, comorbidities, glucose-lowering medications, baseline ED and hospital visits for hypoglycemia and hyperglycemia, and baseline deductible amount, and applying inverse propensity score weighting to account for potential treatment selection bias. The study population was composed of 42 326 patients who switched to an HDHP (mean [SD] age: 52 [10] years, 19 752 [46.7%] women, 7375 [17.4%] Black, 5740 [13.6%] Hispanic, 26 572 [62.8%] non-Hispanic White) and 202 729 patients who did not switch (mean [SD] age, 53 [10] years, 89 828 [44.3%] women, 29 551 [14.6%] Black, 26 689 [13.2%] Hispanic, 130 843 [64.5%] non-Hispanic White). When comparing all study years, switching to an HDHP was not associated with increased odds of experiencing at least 1 hypoglycemia-related ED visit or hospitalization (OR, 1.01 [95% CI, 0.95-1.06]; P = .85), but each year of HDHP enrollment did increase these odds by 2% (OR, 1.02 [95% CI, 1.00-1.04]; P = .04). In contrast, switching to an HDHP did significantly increase the odds of experiencing at least 1 hyperglycemia-related ED visit or hospitalization (OR, 1.25 [95% CI, 1.11-1.42]; P < .001), with each year of HDHP enrollment increasing the odds by 5% (OR, 1.05 [95% CI, 1.01-1.09]; P = .02). In this cohort study, employer-forced switching to an HDHP was associated with increased odds of potentially preventable acute diabetes complications, potentially because of delayed or deferred care. These findings suggest that employers should be more judicious in their health plan offerings, and health plans and policy makers should consider allowing preventive and high-value services to be exempt from deductible requirements.

Evaluation of a high-speed hybrid OAM-OFDM-MDM multiplexed coherent FSO system under desert conditions

To meet the needs of future wireless optical networks, this paper introduces a high-speed, hybrid multiplexed, coherent free-space optical (FSO) communication system that integrates an orbital angular momentum (OAM) multiplexed signal with an orthogonal frequency division multiplexing (OFDM) technique. Two independent QAM polarized beams, each carrying in-phase and quadrature (I/Q) phase 16-QAM-OFDM modulated data, are combined using mode division multiplexing (MDM) to increase the capacity of the proposed system. The reason of choosing OFDM is its capability to support higher data rate, and mitigating intersymbol interference (ISI). The signal is detected using a coherent detection-based digital signal processing (DSP) algorithm at the receiver end. The proposed hybrid FSO system is evaluated in low and heavy dust environments using bit error rate (BER), link distance, optical signal-to-noise ratio (OSNR), and received optical power performance matrices. The simulation results demonstrate the successful transmission of a 120 Gb/s single carrier over the longest link ranges of 1.5 and 0.40 km, respectively, under low and heavy dust weather environments below the signal degradation threshold value (forward error correction (FEC) limit) of BER 2.2 × 10–3 in strong turbulent conditions.

Paper] Study on Single Frequency Downlink with Coupling Loop Interference Canceller for Professional SC-FDE Wireless Camera using Millimeter-wave Band

Professional wireless cameras using the millimeter-wave band can transmit more information than those in the UHF band, making this band especially useful for transmitting high-quality video and audio with low latency. Although such devices have been put into practical use, there is a need to downsize the equipment on the camera side to reduce expensive millimeter-wave band components and improve operability. In this study, we configure the downlink of a professional wireless camera for UHDTV as a single frequency network (SFN) and study the expansion of coverage provided by a booster. A coupling loop interference canceller and multi-path equalizer are installed in the booster. A computer simulation shows that the booster works well. SFN interference, in which the master and booster waves multiply propagate, can be equalized through frequency domain equalization (FDE) of the single-carrier (SC) system at the receiver side.

Structural design of dual carrier multiplication avalanche photodiodes on InP substrate

Avalanche photodiodes are widely used in various fields, such as optical communication and laser radar, because of their high multiplication. In order to adapt to very weak signal detection applications, devices are required to have higher gain values. The existing avalanche photodiodes generally use single carrier multiplication mode of operation, its multiplication effect is limited. In this paper is designed an InP/In&lt;sub&gt;0.53&lt;/sub&gt;Ga&lt;sub&gt;0.47&lt;/sub&gt;As/In&lt;sub&gt;0.52&lt;/sub&gt;Al&lt;sub&gt;0.48&lt;/sub&gt;As avalanche photodiode structure with electrons and holes jointly involved in multiplication. In this structure, In&lt;sub&gt;0.53&lt;/sub&gt;Ga&lt;sub&gt;0.47&lt;/sub&gt;As material is used for the absorption layer, InP material is used for the hole multiplication layer, In&lt;sub&gt;0.52&lt;/sub&gt;Al&lt;sub&gt;0.48&lt;/sub&gt;As is used for the electron multiplication layer, and the two multiplication layers are distributed on the upper side and lower side of the absorber layer. Under the reverse bias, the photogenerated electrons and the absorber-layer generated holes can enter into the respective multiplier layers in different directions and create the avalanche multiplication effect, so that the carriers are fully utilized. This structure and the conventional single multiplication layer structure are simulated by Silvaco TCAD software. Comparing the single InP multiplication layer structure with the single In&lt;sub&gt;0.52&lt;/sub&gt;Al&lt;sub&gt;0.48&lt;/sub&gt;As multiplication layer structure, the gain value of the double multiplication layer structure at 95% breakdown voltage is about 2.3 times and about 2 times of the former two, respectively, and the device has a larger gain value because both carriers are involved in multiplication in both multiplication layers at the same time. The structure has a dark current of 1.5 nA at 95% breakdown voltage, which does not increase in comparison with the single multiplication layer structure, owing to the effective control of the electric field inside the structure by multiple charge layers. Therefore, this structure is expected to improve the detection sensitivity of the system.

Effect of fertilizers enriched with bio-based carriers on selected growth parameters, grain yield and grain quality of maize (Zea mays L.)

Low efficiency of nutrient use, especially nitrogen, from mineral fertilizers under the drought conditions is a worldwide problem in agriculture. Therefore, low-cost, and environmentally friendly technologies that improve the utilization of nutrients from applied fertilizers while increasing water availability to plants are urgently needed. The aim of our research was to prepare bio-based carriers composed from different ratios of natural hydroabsorbent (NHA), synthetic superabsorbent polymer (SAP), and zeolite. The commercial fertilizers (NP and NPK) were enriched with these carriers with subsequent determination of their ability to release nutrients and affect the growth of maize plants grown under drought conditions. The first (i) part of our experiment focused on the lab preparation of bio-based carriers followed by a testing of their abilities to release nitrogen into water in the lab conditions. The effect of selected carriers in the mixture with commercial fertilizers to the growth of maize were subsequently tested under the optimal and limited watering regime in the greenhouse pot experiment (ii). The control treatment (no fertilizer) and fertilization treatments were established, namely, single bio-based carrier (C2) and compound fertilizers (NP, NPK) and their mixture (C2-NP, C2-NPK). The effect of these fertilizers applied in two doses (at the level of 30 and 60 kg/ha N) on the yield and grain quality of maize (iii) was finally evaluated in a two-year field experiment (2020 – 2021). Based on the existing kinetic models, it was possible to the link nitrogen release to the structural variables of the composite carriers. A small volume of zeolite microparticles incorporated into the biopolymer network of the NHA and SAP carrier accelerated the nitrogen release in the lab experiment (i) and increased the maximum amount of released nitrogen in proportion to the zeolite content without significantly affecting the water-holding capacity. The results of the greenhouse pot experiment (ii) demonstrated that application of a bio-based carrier composed of 7 wt% SAP, 7 wt% zeolite and 86 wt% NHA in combination with NP and NPK fertilizers significantly increased chlorophyll content, the ability of maize plants to absorb radiation in photosystem II, and the weight of above-ground maize biomass under limited and optimal irrigation conditions. The C2-NPK increased grain weight, grain yield and protein content in the grain of maize under the field conditions (iii). Fertilizers enriched with bio-based carrier are a promising alternative to improve soil moisture and increase nutrient availability to plants grown not only in drought conditions.

Grant-Free Non-Orthogonal Multiple Access in Single-Carrier Frequency-Selective Fading Channels

Grant-free (GF) access is one key technology for massive machine-type communication (mMTC) in Internet-of-things. Single-carrier (SC) modulation has higher power-efficiency than multicarrier modulation such as orthogonal frequency division multiplexing, due to lower peak-to-average power ratio, and thus is specifically suitable for low-power-supply machine-type devices. In this paper, we study both the coherent and non-coherent grant-free non-orthogonal multiple access (GF-NOMA) schemes where SC modulation is employed in frequency selective fading channels. For coherent SC-GF-NOMA, the linear input-output relation is first presented, and two user-activity detection (UAD) algorithms, block covariance-based maximum-likelihood detection (CB-MLD) and turbo approximated message passing (Turbo AMP), are proposed. In block CB-MLD, a block update strategy is introduced in the coordinate descent iteration to utilize the special block-sparsity signal property inherent in coherent SC-GF-NOMA. Moreover, Turbo AMP consists of two components, AMP and message passing (MP), and turbo iteration between them. Concretely, AMP is designed for UAD-CE with fixed active user probability, and MP is designed to update the active user probability by utilizing the block sparsity. Moreover, the performance of Turbo AMP is analyzed by state-evolution (SE) formalism. For non-coherent SC-GF-NOMA, the linear input-output relation is first derived from which the hierarchical block-sparsity signal property is observed, and then block CB-MLD-based UAD algorithm is presented to utilize this signal property. Finally, computer simulation results are given to demonstrate the effectiveness of the proposed algorithms in both coherent and non-coherent SC-GF-NOMA.

Engineered upconversion nanocarriers for synergistic breast cancer imaging and therapy: Current state of art.

Breast cancer is the most common type of cancer in women and is the second leading cause of cancer-related deaths worldwide. Early diagnosis and effective therapeutic interventions are critical determinants that can improve survival and quality of life in breast cancer patients. Nanotheranostics are emerging interventions that offer the dual benefit of in vivo diagnosis and therapeutics through a single nano-sized carrier. Rare earth metal-doped upconversion nanoparticles (UCNPs) with their ability to convert near-infrared light to visible light or UV light in vivo settings have gained special attraction due to their unique luminescence and tumor-targeting properties. In this review, we have discussed applications of UCNPs in drug and gene delivery, photothermal therapy (PTT), photodynamic therapy (PDT) and tumor targeting in breast cancer. Further, present challenges and future opportunities for UCNPs in breast cancer treatment have also been mentioned.

Fully synthetic Tn-based three-component cancer vaccine using covalently linked TLR4 ligand MPLA and iNKT cell agonist KRN-7000 as built-in adjuvant effectively protects mice from tumor development.

We present a new strategy for self-adjuvanting vaccine development that has different types of covalently-linked immunostimulants as the carrier molecule. Using Tn antigen as the model, a three-component vaccine (MPLA-Tn-KRN7000) containing the TLR4 ligand MPLA and the iNKT cell agonist KRN7000 was designed and synthesized. This expands fully synthetic self-adjuvanting vaccine studies that use a single carrier to one with two different types of carriers. The corresponding two-component conjugate vaccines Tn-MPLA, Tn-KRN7000 and Tn-CRM197 were also synthesized, as controls. The immunological evaluation found that MPLA-Tn-KRN7000 elicits robust Tn-specific and T cell-dependent immunity. The antibodies specifically recognized, bound to and exhibited complement-dependent cytotoxicity against Tn-positive cancer cells. In addition, MPLA-Tn-KRN7000 increased the survival rate and survival time of tumor-challenged mice, and surviving mice reject further tumor attacks without any additional treatment. Compared to the glycoprotein vaccine Tn-CRM197, the two-component conjugate vaccines, Tn-MPLA and Tn-KRN7000, and the physical mixture of Tn-MPLA and Tn-KRN7000, MPLA-Tn-KRN7000 showed the most effect at combating tumor cells both invitro and invivo. The comparison of immunological studies in wild-type and TLR4 knockout mice, along with the test of binding affinity to CD1d protein suggests that the covalently linked MPLA-KRN7000 immunostimulant induces a synergistic activation of TLR4 and iNKT cell that improves the immunogenicity of Tn. This work demonstrates that MPLA-Tn-KRN7000 has the potential to be a vaccine candidate and provides a new direction for fully synthetic vaccine design.

A Millimeter-Wave GaN MMIC Front End Module with 5G NR Performance Verification

This paper proposes a millimeter-wave (mmWave) 5G front end module (FEM) based on multiple gallium nitride (GaN) monolithic microwave integrated circuits (MMICs) with 5G new radio (NR) performance verification. The proposed structure is configured by a wide band GaN single-pole double-throw (SPDT) switch MMIC, a GaN low-noise amplifier (LNA) MMIC, and a GaN power amplifier (PA) MMIC with the target operation band from 26.5 GHz to 29.5 GHz. The LNA and PA MMICs are designed with 150 nm GaN/SiC technology, and the SPDT MMIC is designed with 100 nm GaN/Si. The LNA MMIC shows the measured noise figure less than or equal to 2.52 dB within the operation band. The PA MMIC is based on a two-stage configuration and shows about 35 dBm measured saturated power with power-added efficiency better than 34% within the operation band. Also, the SPDT MMIC is based on an artificial transmission line configuration for wideband performance and shows that the measured insertion loss is less than 1.6 dB, and the measured isolation is higher than 25 dB within the operation band. Furthermore, all MMICs are integrated within a single carrier as an FEM and successfully verified by 5G NR test signals.

The research on channel estimation and signal‐noise ratio estimation based on minimum error entropy kalman filter for single carrier frequency domain equalization system

SummaryIn this paper, the channel estimation and signal‐to‐noise ratio (SNR) estimation technique of single‐carrier frequency domain equalization (SC‐FDE) system under low SNR in aeronautical multipath channel are studied, a SNR estimation algorithm which is easy to implement in engineering and an improved LS channel estimation algorithm based on Kalman filter using minimum error entropy (MEE‐KF) are proposed. This paper first introduces the SC‐FDE system and introduces the principle of MEE‐KF, and then, the channel estimation flow based on MEE‐KF is obtained by combining it with the traditional LS channel estimation algorithm, which makes the estimation results perform better. Simulation results show that after getting more accurate noise variance, the channel estimation results can better follow the changes of the channel after MEE‐KF processing, so as to resist the doppler frequency offset effect and make the channel estimation results more accurate, that is the channel response results of the data part can be closer to the real situation, so that the communication performance of SC‐FDE system has also been greatly improved.

Dynamic Salmonella Enteritidis biofilms development under different flow conditions and their removal using nanoencapsulated thymol

In food industries, microbial contaminations are difficult to control due to the recurrent formation of biofilms that hinders antimicrobials penetration and efficiency. An understanding of Salmonella Enteritidis biofilms behavior under flow conditions is a key to develop efficient preventive and control strategies. S. Enteritidis biofilms displayed 5.96, 6.28 and 6.80 log CFU cm−2 under 0.006 cm s−1, 0.045 cm s−1, and 0.087 cm s−1 flow velocities, respectively. Biofilms exposed to higher nutrient conditions under greater flow rates, induced significantly more biofilm biomass. To control biofilms, the disinfection efficiency of thymol (THY) was assessed under dynamic conditions by encapsulation it into two types of nanocapsules: monolayer (ML) nanocapsules prepared with a single carrier material (maltodextrin), and layer-by-layer (LBL) nanocapsules prepared by combining two carrier materials (maltodextrin and pectin). A combined mixture of ML and LBL nanocapsules at ½ their minimal inhibitory concentrations induced 99.99% eradication of biofilms developed under the highest flow conditions, after 5 h. ML nanocapsules decreased significantly bacterial counts during the first 0.5 h, while LBL nanocapsules eliminated the remaining bacterial cells and ensured a protection from bacterial contamination for up to 5 h by releasing THY in a sustained manner over time due to the thicker shell wall structure.

The paired mail carrier problem

Often traditional mail carrier models assume that one carrier is assigned to each truck. This carrier drives the truck according to a delivery route, gets out of the truck at a stop, and services customers using a walking loop. We introduce the Paired Mail Carrier Problem (PMCP), which allows for two mail carriers per truck. If at least one carrier is in the truck, the truck may move forward. Given two mail carriers per truck, the objective is to minimize the time from the start to the end of the route while ensuring that each service stop is fully serviced and obeys all feasibility constraints. We develop a mixed integer programming (MIP) formulation and two fast heuristics for the PMCP. The MIP formulation obtains optimal solutions for smaller instances within reasonable running times. Furthermore, we demonstrate that, in addition to being very efficient (running time is on the order of milliseconds, even for large instances), our heuristics are near-optimal (within 5% of optimality) on instances up to 80 stops. More importantly, we evaluate the impact of the paired mail carrier (PMC) setting on both a one-truck situation and a fleet (multiple trucks) situation, relative to the single mail carrier (SMC) setting. Overall, the PMC setting not only can accomplish over 50% extra work within the same shift hours but also can lead to 22% cost savings. Finally, we discuss an extension where we can have three or more mail carriers per truck.

Co-Delivery of 8-Hydroxyquinoline Glycoconjugates and Doxorubicin by Supramolecular Hydrogel Based on α-Cyclodextrin and pH-Responsive Micelles for Enhanced Tumor Treatment.

The sustained release of multiple anti-cancer drugs using a single delivery carrier to achieve a synergistic antitumor effect remains challenging in biomaterials and pharmaceutics science. In this study, a supramolecular hydrogel based on the host-guest complexes between pH-responsive micelle derived poly(ethylene glycol) chains and α-cyclodextrin was designed for codelivery of two kinds of anti-cancer agents, hydrophilic 8-hydroxyquinoline glycoconjugate and hydrophobic doxorubicin. The host-guest interactions were characterized using X-ray diffraction and differential scanning calorimetry techniques. The resultant supramolecular hydrogel showed thixotropic properties, which are advantageous to drug delivery systems. In vitro release studies revealed that the supramolecular hydrogel exhibited faster drug release profiles in acidic conditions. The MTT assay demonstrated a synergistic cancer cell proliferation inhibition of DOX/8HQ-Glu mixture. In vitro cytotoxicity studies indicated excellent biocompatibility of the supramolecular hydrogel matrix, whereas the DOX/8HQ-Glu-loaded supramolecular hydrogel showed a sustained inhibition efficacy against cancer cells. The codelivery of hydrophobic anti-cancer drugs and hydrophilic anti-cancer drug glycoconjugates via a pH-responsive supramolecular hydrogel opens up new possibilities for the development of an effective cancer treatment based on the tumor-specific Warburg effect.