External Supply Research Articles

Using TiO2 to capture hot electrons for self-powered position-sensitive photodetection.

As environmental issues arise, the demand for self-powered position-sensitive detectors (PSDs) is increasing because of their advantages in miniaturization and low power consumption. Finding higher efficiency schemes for energy conversion is paramount for realizing high-performance self-powered PSDs. Here, a surface plasmon-based approach was used to improve the energy conversion efficiency, and a plasmon-enhanced lateral photovoltaic effect (LPE) was observed in PSD with TiO2/Au nanorods (NRs)/Si structure. The Au NRs convert absorbed light energy into electricity by generating hot electrons, which are efficiently captured by the TiO2 layer, and the PSD is capable of generating position sensitivity as high as 251.75 mV/mm when illuminated by a 780 nm laser without any external power supply, i.e. about five times higher than similar sensors in previous studies. In addition, the position sensitivity can be tailored by the thickness of TiO2 films. The enhancement mechanism is investigated by a localized surface plasmon (LSP)-driven carrier diffusion model. These findings reveal an important strategy for high sensitivity and low energy cost PSDs while opening up new avenues for energy harvesting self-powered position sensors.

Reconfigurable metasurface design via coplanar self-biasing structure

Reconfigurable metasurface enriches the functional integrated design into the originally limited space. Electrical control, through the external power supply to control the electromagnetic response control, is a common and simple control method. However, current methods of electrical control require external biasing circuits and even metallized through-holes to power the metasurface, thus leading the design and machining of the metasurface more complicated. In order to address this problem, we propose a coplanar self-biasing structure with feeder-structure multiplexing. Metasurface design is generated under connectivity control, and the electromagnetic responses under different voltage states are searched. The designed metasurface is fabricated and verified by measurement, which can prove that the metasurface can control one-dimensional far-field scattering beams. Moreover, the deicing function of the metasurface with integrated biasing line is verified by infrared measurement. All the measured results are consistent well with the expected targets, which shows the effectiveness of our ideas. Importantly, our design opens up a new way to simplify the reconfigurable metasurfaces design, which has a wide application value in the dynamic control of metasurfaces.

Electricity Generation at Gas Distribution Stations from Gas Surplus Pressure Energy

At gas distribution stations (GDSs), the process of throttling (pressure reduction) of natural gas occurs on gas pressure regulators without generating useful energy. If the gas expansion process is created in a turbine, to the shaft where an electric generator is connected, then electricity can be obtained. At the same time, the recycling of secondary energy resources is provided, which is an important component in the efficient use of natural resources. The obtained electric power can be supplied to the external power grid and/or used for the GDS’s own needs. The process of generating electricity at the GDS from gas overpressure energy is an environmentally friendly, energy-saving technology that ensures an uninterrupted, autonomous operation of the GDS in the absence of an external energy supply. The power needs of a GDS with regard to electricity are relatively small (5 ÷ 20 kW). Expansion in throttling devices or turbine flow paths leads to gas cooling with a possible hydrate formation. It is prevented via gas preheating or vortex expansion equipment that keeps the further gas temperature at a necessary level. Turbogenerators can be created on the basis of vortex expansion turbomachines, which have many advantages compared to turbomachines of other types. This article studies how gas pressure (outlet: gas distribution station) and gas preheating (inlet: vortex expansion machine) influence turbogenerator parameters. Nine turbogenerator variants for the power needs of gas distribution stations have been assessed.

Self‐Powered Electrochemiluminescence for Imaging the Corrosion of Protective Coating of Metal and Quantitative Analysis

AbstractIn almost all electrochemical systems for electrochemiluminescence (ECL) analysis, electrodes are connected with an external power source, either directly or via wireless energy transfer circuit. That is inconvenient and makes some applications impossible. Herein, we use galvanized iron with two different metals as both power source and electrodes to achieve a self‐powered ECL and exploit ECL for the imaging of the corrosion of protective coating of widely used metal (e.g. galvanized iron) for the first time. The self‐powered ECL enables the visualization of the deterioration of galvanic coating on iron using a smartphone and the detection of ascorbic acid with a linear range of 0.5–100 μM and a limit of detection of 0.31 μM. The devices based on self‐powered approach do not require external power supply, thus effectively reducing their volume and cost. The self‐powered ECL holds great promise for metal corrosion imaging and analytical applications.

Holocene aeolian environmental dynamics in fixed and semi-fixed deserts over the arid Central Asia revealed by comprehensive sand-dune records

Fixed and semi-fixed deserts are widely distributed in arid Central Asia (ACA). Environmental changes in these deserts can affect the regional radiation balance, climate dynamics, and global climate through a series of feedback effects. This study analyzed luminescence dating from 37 sites, with a particular focus on dendritic dunes (a pattern of vegetated linear dunes) and the ancient dunes beneath them in the Gurbantunggut Desert and yielded the following insights. (1) Primary ridges of dendritic dunes originated approximately 1.0 ka, whereas secondary ridges predominantly formed at 8.5 ± 0.3 ka. The formation of the underlying ancient dunes commenced at least 11.0 ± 0.5 ka and ended between 8.5 ± 0.3 ka and 8.2 ± 0.4 ka. (2) During the Holocene, the Gurbantunggut Desert underwent two distinct environmental phases. From 11.7 ka to 8.1 ± 0.1 ka, the region was characterized by vigorous aeolian activity, marked by the prevalence of mobile dunes. Conversely, the period from 8.1 ± 0.1 ka to 0 ka exhibited substantial environmental amelioration, with limited aeolian activity and the intermittent partial development of vegetated linear dunes. (3) A comprehensive analysis of the principal factors affecting regional aeolian activity revealed that at 11.7 ka–8.1 ± 0.1 ka, moisture (precipitation) and near-surface wind intensity primarily governed aeolian activity in the Gurbantunggut Desert. At 8.1 ± 0.1 ka–0 ka, aeolian activity was mainly influenced by moisture (precipitation), near-surface wind intensity, and external sand supply. (4) Similar patterns of Holocene aeolian activity were observed in the fixed Bayanbulak, Karakum, and Kizil Kum Deserts within the ACA. On a suborbital scale, winter insolation served as the primary driving factor, along with the ice volume and atmospheric CO2 concentration. These factors collectively controlled regional winter temperatures, which determined moisture (precipitation) and near-surface wind intensity by affecting the winter westerlies and Siberian High, ultimately controlling regional aeolian activity.

Self-powered strain sensing devices with wireless transmission: DIW-printed conductive hydrogel electrodes featuring stretchable and self-healing properties

With rapid advancements in health and human–computer interaction, wearable electronic skins (e-skins) designed for application on the human body provide a platform for real-time detection of physiological signals. Wearable strain sensors, integral functional units within e-skins, can be integrated with Internet of Things (IoT) technology to broaden the applications for human body monitoring. A significant challenge lies in the reliance of most existing wearable strain sensors on rigid external power supplies, limiting their practical flexibility. In this study, we present an innovative strategy to fabricate glutaraldehyde (GA)-poly(vinyl alcohol) (PVA)/cellulose nanocrystals (CNC)/Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) conductive hydrogels through multiple hydrogen bonding systems. Combining the advantageous rheological properties of the precursor solution and the high specific surface area after freeze–thaw cycling, we have created a self-powered sensing system prepared by large-area printing using direct ink writing (DIW) printing. The resulting conductive hydrogel exhibits commendable mechanical properties (411 KPa), impressive stretchability (580 %), and robust self-healing capabilities (>98.3 %). The strain sensor, derived from the conductive hydrogel, demonstrates a gauge factor (GF) of 2.5 within a stretching range of 0–580 %. Additionally, the resultant supercapacitor displays a peak energy density of 0.131 mWh/cm3 at a power density of 3.6 mW/cm3. Benefiting from its elevated strain response and remarkable power density features, this self-powered strain sensing system enables the real-time monitoring of human joint motion. The incorporation of a 5G transmission module enhances its capabilities for remote data monitoring, thereby contributing to the progress of wireless tracking technologies for self-powered electronic skin.

Ultrafast Self‐Charging in Acid–Base Free Aqueous Rechargeable Zinc–Quinhydrone Batteries

AbstractIn the field of energy technologies, self‐charging batteries are receiving extensive attention. However, the existing technologies are highly dependent on the available sources of O2, have long self‐charging duration, and have complex architectures. Herein, a novel ultrafast chemical self‐charging Zn‐quinhydrone polymer gel (QPG) battery, composed of acid/base free quinhydrone as a cathode material is reported. The prepared Zn–QPG battery exhibits a specific capacity of 209.7 mAh g−1 at 10C rate and maintains 86.4% of the initial discharge capacity even after 3000 cycles with a high coulombic efficiency of 99.4%. The aqueous amphiphilic block co‐polymer‐driven selective oxidation of hydroquinone (HQ) to benzoquinone (BQ) compels the chemical self‐charging feature wherein the device attains ≈1.1 V within ten minutes of complete discharge. The chemical self‐charging generated a high specific capacity of 197.8 mAh g−1 at 10C rate with a capacity retention of 91.2% after 100 cycles. Moreover, a flexible Zn–QPG battery also demonstrates excellent rechargeability and power‐delivering ability even in a wrist‐bend geometry. This work paves the way to develop ultrafast energy storage systems, which are not dependent on an external power supply and broaden the horizon of aqueous zinc–organic batteries.

Tribological Performance of Soft Magnetic Composite Materials for Gas Turbine Applications

Abstract Soft magnetic composites (SMCs) have gained attention in the last years of their usage in more compact and powerful electromechanical systems. These materials are used to combine the application of metallic material to the capability of generating (without external supply) a magnetic field. Automotive and aerospace technologies push the applications of these original materials to even higher power and mechanical stress to reduce the number of components, the size, and, in turn, the weight of complex systems. Considering gas turbine application, SMCs were formerly developed for bearings, but in the last decades, the new era of gas turbine electrification (e.g., hybrid-electric fly) has determined the need for mechanical improvement of such materials. At the same time, the reliability of soft magnetic material has to be discovered to avoid failure and reduce the maintenance schedule. In the present work, tribological behaviors of SMCs were investigated by standard wear tests. Two different types of SMSc were prepared through the powder metallurgy technique. Tests were conducted by a tribometer using a ball-on-disk configuration in lubricated condition. The effect of oil temperature and applied load were investigated. In addition, an extensive post-mortem analysis was conducted on the worn surface to recognize the mechanisms responsible for the deterioration of the materials. The results showed the effects of the oil viscosity on the useful operating life of the SMCs. Removal mechanisms depend on the load conditions, and the proper selection of the oil characteristics and load was assessed.

Academy of Breastfeeding Medicine Position Statement: Breastfeeding in Emergencies.

Background: During emergencies, including natural disasters and armed conflict, breastfeeding is critically important. Breastfeeding provides reliable nutrition and protection against infectious diseases, without the need for clean water, feeding implements, electricity, or external supplies. Key Information: Protection, promotion, and support of breastfeeding should be an integral part of all emergency preparedness plans. Breastfeeding specialists should be part of plan development. Emergency protocols should include breastfeeding specialists among emergency relief personnel, provide culturally sensitive environments for breastfeeding, and prioritize caregivers of infants in food/water distribution. Emergency relief personnel should be aware that dehydration and missed feedings can impact milk production, but stress alone does not. Emergency support should focus on keeping mothers and infants together and providing private and/or protected spaces for mothers to breastfeed or express milk. Emergency support should also focus on rapidly identifying mothers with breastfeeding difficulties and breastfeeding mothers and infants who are separated, so their needs can be prioritized. Breastfeeding support should be available to all women experiencing difficulties, including those needing reassurance. Nonbreastfed infants should be identified as a priority group requiring support. Relactation, wet-nursing, and donor milk should be considered for nonbreastfed infants. No donations of commercial milk formula (CMF), feeding bottles or teats, or breast pumps should be accepted in emergencies. The distribution of CMF must be highly controlled, provided only when infants cannot be breastfed and accompanied by a comprehensive package of support. Recommendations: Protecting, promoting, and supporting breastfeeding should be included in all emergency preparedness planning and in training of personnel.

Increase in marginal sea alkalinity may impact air–sea carbon dioxide exchange and buffer acidification

AbstractTotal alkalinity (TA) has increased in the Baltic Sea, with implications for atmospheric CO2‐induced acidification and CO2 uptake. We compiled extensive data of TA in surface waters of the Baltic Sea, aiming to (i) identify new tendencies in the relationship between TA and salinity (TA–S relationship), (ii) update the TA trend analysis, (iii) investigate spatial–temporal patterns, and (iv) discuss potential drivers and implications. We observed a progressive decrease in the slopes and increase in the intercepts of the TA–S overtime due to the persistent process of TA enhancement. A weak seasonal pattern was identified, with warmer months presenting lower salinity and TA. Lower rates of TA increase were observed in high salinities (Skagerrak–Kattegat; +1.00 to +2.20 μmol kg−1 yr−1), intermediate trends in low salinities (Gulf of Bothnia; +3.28 to +3.57 μmol kg−1 yr−1), and maximal trends in the Central Baltic Sea (+3.70 to +4.57 μmol kg−1 yr−1) and Bornholm Basin (+4.82 to +5.32 μmol kg−1 yr−1). The increase in the intercept of the TA–S in the Gulf of Bothnia suggests a progressive increase in the external supply of TA, although lower than previously thought. The maximum trend in the Bornholm Basin suggests an increase in external supply from the Southern catchment and/or the accumulation of internal production. The positive TA–phosphorus correlations underscore a significant internal source. The TA increase amplifies the CO2 uptake by 1.8–7.8% during spring/summer and reduces the CO2 outgassing by 3.4–7.7% in autumn/winter. The TA enhancement has the potential to buffer CO2‐induced acidification by 39–60% by 2050.

Engineering the cell wall reactive groups of Plant Growth Promoting Rhizobacteria by culture strategy for heavy metal removal

This research delved into the effects of nutrient limitation on the level of sporulation and the cadmium adsorption capacity of the bacterium Bacillus sp. isolated from the rhizosphere of endemic soils in the Region of Valparaiso, Chile. The bacteria were subjected to nitrogen limitation in fed-batch mode and were compared to bacteria grown in batch culture without nutrient limitation. The cultures were carried out in a 3 L bioreactor with an external nitrogen supply of ammonium at a flow of 0.123 L h−1. The specific maximum growth rate was 0.42 h−1 in batch and 0.45 h−1 in the exponential phase of the fed-batch.The analysis of sporulation did not show any significant difference between the biomass coming from the fed-batch and batch cultures.It was found that maximum cadmium adsorption capacity varied with culture strategy. The dry biomass grown without nutrient limitation exhibited a maximum adsorption capacity for cadmium of 65.0 mgCd g−1biomass. Conversely, the limited biomass achieved a lower cadmium adsorption capacity of approximately 36.0 mgCd g−1biomass. FTIR analysis showed that nitrogen limitation induced changes in the composition of the outer cell wall, specifically an increase of deacetlylated polysaccharides, reducing the relative amount of secondary amines and proteins from the peptidoglycan matrix. Amino groups from acetylated polysaccharides and proteins have been associated elsewhere with greater cadmium affinity, which could explain the poor results obtained with the nitrogen-restricted biomass. This study shows that new physiological states displaying different adsorption capabilities were effectively obtained by engineering the cell coverage of the bacteria using varying culture strategies. The fed-batch culture proved to be a valuable tool for studying PGPR strains for biosorption and other applications. Exploring diverse nutrient limitations and other pollutants in this bacterium and other members of the PGPR family offer great opportunities to tailor biosorption strategies based on specific conditions, ultimately contributing to sustainable environmental solutions.

The Influencing Mechanism of Household Food Purchasing Behavior and Household Reserve Efficiency under Non-Normal Conditions

Family reserves are an important part of national reserves, and how to do a good job in family reserves is a common concern of the government and society. Under the non-normal conditions of major accidents and disasters, wars, plagues, social unrest, etc., urban food supply mainly depends on external supply guarantee, and urban residents’ risk perception is more sensitive. Based on the Theory of Planned Behavior and Norm Activation Model, this study constructs an analytical framework for the risk perception, perceived behavior control, and family reserve efficacy of urban residents under non-normal conditions from the perspectives of rationality and sensibility, self-interest, and altruism. The perceived behavior control of household food reserves in non-normal conditions is affected by risk perception, subjective norms, and personal norms. On this basis, countermeasures and suggestions are put forward: Urban residents should strengthen their sense of risk and responsibility for storing food at home, reserve food appropriately, and develop a good habit of family saving. On the other hand, it is necessary to pay attention to personal norms, reduce the negative impact of subjective norms on residents, and avoid excessive food storage and food waste.

Role of SbNRT1.1B in cadmium accumulation is attributed to nitrate uptake and glutathione-dependent phytochelatins biosynthesis

Phytoremediation of cadmium (Cd)-polluted soil by using sweet sorghum displays a tremendous potential as it is a fast-growing, high biomass and Cd tolerant energy plant. Previous study has demonstrated SbNRT1.1B expression change is in accordance with enhanced Cd accumulation by external nitrate supply in sweet sorghum. Nevertheless, underlying mechanism of SbNRT1.1B response to Cd stress is still elusive. SbNRT1.1B exhibited a positive response to Cd stress in sweet sorghum. Overexpressing SbNRT1.1B increased primary root length, shoot fresh weight, nitrate and chlorophyll concentrations compared with Col-0 under Cd stress, while complementary SbNRT1.1B rescued these decreased values in mutant chl1–5. Cd concentrations in overexpressing SbNRT1.1B, complementary SbNRT1.1B and Col-0 lines were 3.2–4.1, 2.5–3.1 and 1.2–2.1 folds of that in chl1–5. Consistent with Cd concentrations, non-protein thiol (NPT), reduced glutathione (GSH) and phytochelatins (PCs) concentrations as well as the related genes expression levels showed the same trends under Cd stress. GSH biosynthesis inhibitor failed to reverse the patterns of GSH-dependent PCs concentrations changes in different lines, suggesting that SbNRT1.1B plays an upstream role in GSH-dependent PCs biosynthesis under Cd treatment. Altogether, SbNRT1.1B enhances nitrate concentrations contributing to increased chlorophyll concentrations and GSH-dependent PCs metabolites biosynthesis, thereby improving growth and Cd concentrations in plants.

Controlled drainage with subirrigation systems: Reduce water supply by automatic control

Controlled drainage with subirrigation (CDSI) is a viable measure to supply, retain or discharge groundwater, thereby contributing to freshwater availability in agriculture under changing environmental conditions. Relatively simple CDSI systems can be controlled manually to set a few drainage levels. More advanced systems can be controlled remotely to set any drainage level (between a technical maximum and minimum). CDSI potentially improves hydrological conditions for crop growth, but the required external water supply can be large. Therefore, the objective of this paper is to investigate whether external water supply for subirrigation can be reduced by automatic control of CDSI systems in relation to crop water demand. Field measurements of a CDSI pilot in the Dutch sandy Pleistocene uplands were combined with weather forecasts to simulate the optimal drainage level and day by day water demand and supply using the agro-hydrological Soil, Water, Atmosphere, Plant model (SWAP). Firstly, model simulations showed that the water requirement reduced by 60 mm (dry growing season), 253 mm (average growing season) and 348 mm (wet growing season) using a dynamically managed crest level (CDSI-dyn) compared to using a fixed crest level (CDSI-fix), with minor effects on crop yield. Secondly, model simulations showed that a higher hydraulic resistance to downward seepage, a higher ditch water level or deeper roots reduced the water supply (up to 100 mm). Thirdly, accepting 10 % daily crop drought and oxygen stress for CDSI-dyn reduced the water supply requirement with 235–628 mm (dry vs wet growing season) compared to CDSI-fix. In conclusion, the required water volume for CDSI could be substantially reduced by automated control of the drainage level and water supply rate, while maintaining crop yield or accepting minor reductions, which increases the potential of implementation of CDSI systems.

Construction of Fully Integrated and Energy Self-Sufficient NO2 Gas Sensors Utilizing Zinc-Air Batteries.

Exploration of novel self-powered gas sensors free of external energy supply restrictions, such as light illumination and mechanical vibration, for flexible and wearable applications is in urgent need. Herein, this work constructs a flexible and self-powered NO2 gas sensor based on zinc-air batteries (ZABs) with the cathode of the ZABs also acting as the gas-sensitive layer. Furthermore, the SiO2 coating film, serving as a hydrophobic layer, increases the three-phase interfaces for the NO2 reduction reaction. The constructed sensors exhibit a high sensing response (0.3 V @ 5 ppm), an ultralow detection limit (61 ppb), a fast sensing process (129 and 103 s), and excellent selectivity. Moreover, the sensors also possess a wide working temperature range and a low working temperature tolerance (0.34 V at -15 °C). Simulations indicate that the hydrophobic surface at the cathode-hydrogel interface will accommodate more NO2 gas molecules at the reaction sites and prevent the influence of inner water evaporation and direct dissolution of NO2 in the electrolyte, which is beneficial to the enhanced gas sensing abilities. Finally, the self-powered sensing device is incorporated into a smart sensing system for practical applications. This work will pave a new insight into the construction of integrated and energy self-sufficient smart gas sensing systems.

A Self-Powered, Skin Adhesive, and Flexible Human-Machine Interface Based on Triboelectric Nanogenerator.

Human-machine interactions (HMIs) have penetrated into various academic and industrial fields, such as robotics, virtual reality, and wearable electronics. However, the practical application of most human-machine interfaces faces notable obstacles due to their complex structure and materials, high power consumption, limited effective skin adhesion, and high cost. Herein, we report a self-powered, skin adhesive, and flexible human-machine interface based on a triboelectric nanogenerator (SSFHMI). Characterized by its simple structure and low cost, the SSFHMI can easily convert touch stimuli into a stable electrical signal at the trigger pressure from a finger touch, without requiring an external power supply. A skeleton spacer has been specially designed in order to increase the stability and homogeneity of the output signals of each TENG unit and prevent crosstalk between them. Moreover, we constructed a hydrogel adhesive interface with skin-adhesive properties to adapt to easy wear on complex human body surfaces. By integrating the SSFHMI with a microcontroller, a programmable touch operation platform has been constructed that is capable of multiple interactions. These include medical calling, music media playback, security unlocking, and electronic piano playing. This self-powered, cost-effective SSFHMI holds potential relevance for the next generation of highly integrated and sustainable portable smart electronic products and applications.

A self-powered sensor based on hollow bimetallic sulfide and double-strand TSDR amplification achieves sensitive miRNA-21 detection

MicroRNA (miRNA) sensitive detection is significant for cancer diagnosis. Currently, self-powered biosensors in clinical miRNA detection show the advantages of no external power supply, mild reaction conditions, low cost and portability. In this work, the bimetallic sulfide heterojunction hollow nanocubes are prepared as the substrate material, which can significantly improve the electrochemical reaction rate and increase the enzyme load. Meanwhile, we design the independent duplex-chain assisted toehold mediated strand displacement reaction (TSDR) strategy. The two substable double chains trigger a continuous chain displacement reaction, and the current signal amplification is realized based on molecular recognition. The constructed sensor has a linear response range of 0.05–10000 fM and a detection limit (LOD) of 8.3 aM. In addition, we use commercial apps to present signals, fundamentally changing the signal output mode of electrochemical sensors, and facilitating the construction of a portable real-time sensor platform. The self-powered biosensor has the characteristics of good biocompatibility, real-time monitoring and economic efficiency in miRNA detection, which provides a new idea for sensitive detection of miRNA. Moreover, it has far-reaching reference significance for the development of other sensing technologies, which is expected to extend from the medical field to environmental monitoring, food safety and other fields.

Internal- and external-sourcing strategy analysis of group manufacturing enterprises under semiconductor supply chain disruption risk

Semiconductor manufacturing enterprises face potential risks of supply disruption owing to economic and political factors. To enhance supply stability and industry sustainability, group manufacturing enterprises can establish internal suppliers to supply components exclusively to internal OEMs. However, under the competition from external suppliers and OEMs, it is unclear how group manufacturing enterprises decide on procurement strategies. We construct a two-echelon supply chain game model consisted of four supply chain stakeholders and analyze the group manufacturing enterprise's decision-makings on developing an internal supplier and procurement strategies. We obtain some remarkable findings. The optimal procurement decisions of group manufacturing enterprise, the internal OEM, and the internal supplier are different. Decision makers should consider which enterprise's profit is more important and choose the procurement strategy preferentially. Group manufacturing enterprise, the external supplier, and the competitive OEM cannot achieve a triple-win situation. Even if the internal supplier's technical level is high, the group manufacturing enterprise and the internal OEM cannot gain competitive advantages in the internal-sourcing scenario. Group manufacturing enterprise needs to pay more attention to the environmental impact. Furthermore, we extend the basic model and analyze the robustness of the conclusions.

Analysis of the dynamic model of the impact of external economic shocks on inflationary processes

The past few decades by the emergence of such crises in the economic and social sphere of society, which resulted in economic supply shocks have been marked. Previously extremely rare, they have shifted the focus to the relevance of research on macroeconomic processes affected by shocks of this nature, not only in economic theory, but also in mathematical modelling. As a result of the analysis of already known macroeconomic models, it was revealed that the impact of external economic shocks on the main indicators of macroeconomics can have both negative and positive effects on economic growth. The purpose of the study is to build and analyze a dynamic optimization model, as well as recommendations for developing an optimal economic policy strategy. The article contains a description of the formulation and mathematical formalization of the macroeconomic task of levelling social damage from the impact of an external economic supply shock on the inflationary process and the unemployment rate. The connection between the two latter processes is established on the basis of the equation of the modified Phillips curve, supplemented by inflationary expectations, assuming a short-term perspective. The corresponding to this task economic and mathematical model is classified as an optimization model and represents the task of finding the conditional minimum of the loss functional. The article describes the qualitative analysis of this model, carried out using the methods of calculus of variations, formulas describing the dynamics of the above-mentioned macroeconomic indicators are obtained, a formula is derived for finding the level of inflation expectations at each moment of the time period under consideration. The obtained results of the mathematical model study are interpreted economically, while special attention is paid to the analysis of the impact of the external supply shock on these indicators.

The contribution of logistics to improving health care quality: a case study approach

ABSTRACT This research in a managerial vision tries to understand how inter-organisational logistical collaboration on physical (drugs, consumables, medical equipment and kits) and information flows contributes to improving the quality of care. The analysis of the content of the semi-structured interviews allowed us to discuss the two research proposals resulting from the literature review and their level of acceptance. The results show that the collaboration between the operators of the two supply chains, internal and external supply chains, contributes to improving care but under certain conditions. Recommendations have been made to many entities to improve logistical practices and the quality of care provided to patients. In doing so, our research thus contributes to compiling literature on hospital logistics and paves the way for more future research in the field of logistics in healthcare establishments.