Efficient Barrier Research Articles

The polyphenolic suberized peridermal skin of the Sikkim cucumber acts as an effective chemical barrier against Botrytis cinerea infection

Certain species of fleshy fruit that undergo skin cracking are capable of forming a specialized polyphenolic periderm to seal the wounded skin. Some of the genetic and metabolic components pertaining periderm formation have been identified, however it remains unknown if, and to what extent, this specialized tissue can act as an efficient barrier against the invasion of pathogenic fungi. We monitored the infection process of Botrytis cinerea on the cuticle-coated skin of the common cucumber (Cucumis sativus) or on the polyphenolic suberized peridermal skin of the Sikkim cucumber (C. sativus var. sikkimensis). In vivo inoculation assays inferred that while B. cinerea can successfully penetrate and form necrotic lesions on sativus fruit, it is incapable of penetrating the peridermal skin of sikkimensis fruit. Gas chromatography-mass spectrometry (GC-MS) profiling of fruit skin extracts, in vitro conidial germination and germ tube elongation assays, and qRT-PCR cutinase-encoding gene expression analyses, inferred that the accumulation of suberin monomers in the peridermal skin of sikkimensis fruit stimulate increased elongation of B. cinerea germ tubes and significantly alters the differential expression of cutinase-encoding genes. Among them, Bcin0607010, Bcin08g01580 and Bcin07g06480, three yet unidentified cutinases, whose expression is specifically increased in the presence of sikkimensis fruit skin extracts. Our data demonstrate that a polyphenolic suberized peridermal skin in cucumber fruit can shape the interactions with B. cinerea and implies that suberization of fleshy fruit may provide a means for reducing damage imposed by this and other pathogens.

Ключевые аспекты предупреждения возникновения и минимизации последствий аварий на опасных производственных объектах нефтегазового комплекса

Analysis of the existing legal requirements for operating organizations in terms of preventing the development and minimization of accidents consequences from the point of view of the «technology — equipment — personnel» system was carried out, and measures were proposed that are efficient safety barriers within the framework of the organizations readiness to act to localize and eliminate the accidents consequences. First of all, the operating organizations are obliged to guarantee the safety of the technological system of oil and gas complex facilities. Requirements for ensuring the safety of a technological system are established by the design documentation, including on the basis of calculation methods and hazard analysis of the technological processes. In the course of the conducted analysis of the causes of occurred accidents, it was revealed that one of the most common causes of accidents at the oil and gas complex facilities is the lack of technological regulations or their non-compliance with the established requirements. Carrying out a technological process and performing operations not provided for by the technological regulations can lead to an accident with significant consequences. Based on the analysis, it was revealed that one more of the most common cause of accidents is the operation of buildings, structures and technical devices that expired their established service life. When operating oil and gas complex facilities, special attention should be paid to staffing levels and personnel training. In addition to the mandatory requirements, it is recommended that a standard accident message be developed to help reduce the amount of time spent communicating in stressful situations. Failure to take measures on preventing and minimizing the consequences of accidents can negatively affect the activities of operating organizations, both in terms of image and financial components.

Protection of a defensive symbiont does not constrain the composition of the multifunctional hydrocarbon profile in digger wasps.

Hydrocarbons (HCs) fulfil indispensable functions in insects, protecting against desiccation and serving chemical communication. However, the link between composition and function, and the selection pressures shaping HC profiles remain poorly understood. Beewolf digger wasps (Hymenoptera: Crabronidae) use an antennal gland secretion rich in linear unsaturated HCs to form a hydrophobic barrier around their defensive bacterial symbiont, protecting it from brood cell fumigation by toxic egg-produced nitric oxide (NO). Virtually identical HC compositions mediate desiccation protection and prey preservation from moulding in underground beewolf brood cells. It is unknown whether this composition presents an optimized adaptation to all functions, or a compromise due to conflicting selection pressures. Here, we reconstitute the NO barrier with single and binary combinations of synthetic linear saturated and unsaturated HCs, corresponding to HCs found in beewolves. The results show that pure alkanes as well as 3 : 1 mixtures of alkanes and alkenes resembling the composition of beewolf HCs form efficient protective barriers against NO, indicating that protection can be achieved by different mixtures of HCs. Since in vitro assays with symbiont cultures from different beewolf hosts indicate widespread NO sensitivity, HC-mediated protection from NO is likely important across Philanthini wasps. We conclude that HC-mediated protection of the symbiont from NO does not exert a conflicting selection pressure on the multifunctional HC profile of beewolves.

Ablation behavior, microstructure, phase evolution and in situ ceramization mechanism of ZrC-LaB6 modified carbon fiber/phenolic resin ceramizable composite

Carbon fiber/phenolic resin composite (CF/Ph) has drawn great interest in thermal protection for its characteristics of high specific strength and easy fabrication. However, oxidation failure limits further application of CF/Ph in hostile environments. Herein, a novel carbon fiber/phenolic resin ceramizable composite modified with ZrC and LaB6 was reported. The synergistic effects between ZrC and LaB6 on high-temperature thermal degradation behavior, oxidative corrosion and ablation resistance were systematically studied based on thermal analysis and oxyacetylene ablation experiment of the resulting ceramizable composite as well as microstructure evolution, phase evolution, and thermodynamic calculation analysis of the ablated surface. The resulting ceramizable composite exhibited excellent oxidative corrosion and ablation resistance, with the residue yield at 1500 °C as high as 32.8 % and the linear ablation rate at 4.3 MW/m2 for 30 s as low as -0.00231 mm/s, respectively. Further, the ablation mechanisms were revealed. Dense B-C-O-Zr-La ceramic layers with a mosaic structure, which acted as efficient thermal protection barriers, were constructed in situ, and significantly reduced corrosion to carbon. Moreover, an intense endothermic effect during the carbothermal reaction between ZrO2, B2O3 and PyC led to an abnormally better insulation capacity.

Organizational control for safety: A challenge in socioeconomic and natural environment

AbstractThe concepts and applications of cases in human factors (HFs), risk, reliability, and crisis, include the analysis of complex systems and difficult to predict sociotechnical systems. Rules and barriers are designed or revised to achieve better organizational efficiency results. The investigation then valuates the concepts such as the basis, the tests such as confirmation, the algorithms such as methods and tools, and the validation that indicates the certainty of achieving good results. The human elements (HE) are part of the design and can either disable or enable the flow of hazard energy. The intention is that these HEs inside the safety culture and technology design act as safeguards. The HE avoids design deficiencies, social and physical. HE can reduce load over the resistance capacity. The culture, social phenomenon, company project, management and staff, group and worker, operational control, failure control, and accident and disaster are classes of HF that transform hazard energy and need efficient HE barriers. The internal and external regulation after these discussions needs to revise its principles to correct processes of standardization and organizational communication, which would change the procedures for team building and the criteria for the technology project. An improvement program includes investigation of lessons learned and behavior treatment.

Study on the performance of sealing slurry at the bottom of geomembrane composite vertical cut off walls

At the bottom of the geomembrane cut-off walls, pollutants may seep out through the bottom gap between the geosynthetic membrane and the low-permeability bedrock, contaminating the groundwater and the surrounding environment. Therefore, to address the occurrence of bottom gap seepage, this study adopts a mixture of attapulgite and cement in a certain proportion, mixed and stirred to form a sealing material. This sealing material is used to connect the bedrock and the geosynthetic membrane, thereby creating an efficient composite vertical barrier with special containment capacity. A series of laboratory experiments were conducted to investigate engineering properties of cement-attapulgite sealing slurry, including flow value tests, unconfined compressive strength (UCS) tests, improved flexible wall permeability tests, and bedrock and sealing slurry adhesion tests. The results show that the flow value of the slurry decreases with the increase of attapulgite content, and it increases with the increase of water-cement ratio. The UCS strength increases with the increase of attapulgite content, and it decreases with the increase of water-cement ratio, but the range of change is different. The hydraulic conductivity measured with hexavalent chromium solution as the penetrant is less than 50 % higher than that measured with water as the penetrant, and hexavalent chromium solution has little effect on the hydraulic conductivity of sealing slurry. The bonding performance between sealing slurry and bedrock is satisfactory, and the hydraulic conductivity of bedrock-sealing slurry is less than 1 × 10−7 cm/s (28d curing age), it is concluded that use of cement-attapulgite sealing slurry as bonding material between bedrock and geomembrane meets the engineering design requirements.

Performance of wildlife fence systems under animal impact load

Wildlife fence protection systems specifically designed for animal protection are critical in mitigating wildlife-vehicle collisions and preserving animal habitats. These systems are quite similar to rockfall barrier systems, which are well studied and developed, however, few studies are specifically oriented toward investigating structural performance of these systems. Despite the similarities, results of studies related to rockfall barriers may not be directly applicable to design and performance evaluation of wildlife barrier systems due to differences in a range of size, shape, and velocity of impactors and structural details. This study aims to bridge this gap by analyzing performance and capacity of wildlife structures in more detail through parametric study with consideration of a wide range of properties and structural details appropriate for these systems, such as mesh type (square and inclined), mesh size, and wire diameters. The behavior of these systems under impact loads is simulated using nonlinear finite element models with consideration of ductile damage and element removal techniques to accurately capture wire rupture and changes in the impactor-fence system interface. The results demonstrate that the response of the system is highly influenced by factors such as mesh type, opening size, wire diameter, and impactor size. Notably, the system utilizing an inclined mesh type exhibits a 35 % higher failure velocity, 50 % greater energy dissipation, and 21 % less maximum displacement compared to the square mesh system. The detailed results and discussions in this study provide valuable insights into the influence of individual parameters on the behavior of wildlife fence systems, aiding in the design of more efficient wildlife barrier systems with enhanced performance.

Pemetrexed-layered double hydroxide with Eudragit® S100; 2D van der Waals nanohybrid with drug delivery function

The well-known anti-cancer drug, Pemetrexed (PMX), has low bioavailability upon oral administration owing to its poor chemical stability in a gastrointestinal condition. To conquer this major issue, pemetrexed drug was first intercalated into layered double hydroxide (LDH) to form a PMX-LDH nanohybrid, thereafter Eudragit® S100 (S100), an enteric coating agent, was functionalized to form a 2D van der Waals nanohybrid drug, PMX-LDH-S100, eventually to protect from drug degradation under a gastric condition. According to the pharmacokinetic (PK) study, the AUC, T1/2 and MRT (mean residence time) values for the present 2D van der Waals nanohybrid were determined to be more than three times greater than intact PMX, suggesting that LDH-S100 layers resulted in the formation of efficient barrier to induce a sustained release and prolonged circulation of PMX, and ultimately enhancing the plasma PMX concentration and oral bioavailability. Moreover, orally administered PMX-LDH-S100 significantly inhibited tumor volume in A549 tumor mouse model, suppressing tumor volume by 64% and 51% than PBS and PMX samples. This study indicates that the developed anticancer drug delivery technoloy might be an orally administrable system for PMX to have improved efficacy in cancer treatment.

Co-Impregnated N-Doped Carbon Nanotube/SiO2-Modified Separators as Efficient Polysulfide Barriers for Lithium–Sulfur Batteries

Co-Impregnated N-Doped Carbon Nanotube/SiO₂-Modified Separators as Efficient Polysulfide Barriers for Lithium–Sulfur Batteries

Numerical Simulation and Parameter Optimization of a New Reed–Nylon Net Combined Sand Fence

This paper introduces a kind of double-row reed–nylon net combined sand barrier. Using the computational fluid dynamics (CFD) method and the Euler–Euler double-fluid model, the new sand fences’ windproof effect and airflow features are simulated under different porosities and spacings, and the optimal configuration parameters are selected. The new sand fence has better windproof performance and practical significance than double-row reed and double-row nylon net fences. The new sand fences with a porosity of 0.3–0.4 and spacing of 28 H provide a longer protection range and a better wind protection effect. Considering the serious sand damage in China’s Taklamakan Desert, the new fences’ impact on sand buildup is examined. The combined sand fences have powerful sand blocking and accumulation effects, even though there is only a small quantity of sand accumulation on the leeward side of the second row. The sand particles primarily settle between sand fences in the center and rear areas. The combination of sand fences made of different materials combines the advantages of both, improves the construction efficiency and service life, and provides a more economical and efficient sand barrier arrangement for the arrangement of wind and sand-blocking facilities around railroads and highways in desert areas.

Single-cell transcriptomics identifies new blood cell populations in Drosophila released at the onset of metamorphosis.

Drosophila blood cells called hemocytes form an efficient barrier against infections and tissue damage. During metamorphosis, hemocytes undergo tremendous changes in their shape and behavior, preparing them for tissue clearance. Yet, the diversity and functional plasticity of pupal blood cells have not been explored. Here, we combine single-cell transcriptomics and high-resolution microscopy to dissect the heterogeneity and plasticity of pupal hemocytes. We identified undifferentiated and specified hemocytes with different molecular signatures associated with distinct functions such as antimicrobial, antifungal immune defense, cell adhesion or secretion. Strikingly, we identified a highly migratory and immune-responsive pupal cell population expressing typical markers of the posterior signaling center (PSC), which is known to be an important niche in the larval lymph gland. PSC-like cells become restricted to the abdominal segments and are morphologically very distinct from typical Hemolectin (Hml)-positive plasmatocytes. G-TRACE lineage experiments further suggest that PSC-like cells can transdifferentiate to lamellocytes triggered by parasitoid wasp infestation. In summary, we present the first molecular description of pupal Drosophila blood cells, providing insights into blood cell functional diversification and plasticity during pupal metamorphosis.

Enhancement of Microglia Functions by Developed Nano-Immuno-Synergist to Ameliorate Immunodeficiency for Malignant Glioma Treatment.

Resident microglia are key factors in mediating immunity against brain tumors, but the microglia in malignant glioma are functionally impaired. Little immunotherapy is explored to restore microglial function against glioma. Herein, oleanolic acid (OA) (microglia "restorer") and D PPA-1 peptide (immune checkpoint blockade) are integrated on a nano-immuno-synergist (D PAM@OA) to work coordinately. The self-assembled OA core is coated with macrophage membrane for efficient blood-brain barrier penetration and microglia targeting, on which D PPA-1 peptide is attached via acid-sensitive bonds for specific release in tumor microenvironment. With the enhanced accumulation of the dual drugs in their respective action sites, D PAM@OA effectively promotes the recruitment and activation of effector T cells by inhibiting aberrant activation of Signal transducer and activator of transcription (STAT-3) pathway in microglia, and assists activated effector T cells in killing tumor cells by blocking elevated immune checkpoint proteins in malignant glioma. Eventually, as adjuvant therapy, the rationally designed nano-immuno-synergist hinders malignant glioma progression and recurrence with or without temozolomide. The work demonstrates the feasibility of a nano-formulation for microglia-based immunotherapy, which may provide a new direction for the treatment of brain tumors.

A Nanodisc-Paved Biobridge Facilitates Stem Cell Membrane Fusogenicity for Intracerebral Shuttling and Bystander Effects.

Mesenchymal stem cell (MSC) therapies experience steadfast clinical advances but are still hindered by inefficient site-specific migration. An adaptable MSC membrane fusogenicity technology is conceptualized for lipid raft-mediated targeting ligand embedding by using toolkits of discoidal high-density lipoprotein (HDL)-containing biomimicking 4F peptides. According to the pathological clues of brain diseases, the vascular cell adhesion molecule 1 specialized VBP peptide is fused with 4F to assemble 4F-VBP (HDL), which acts as a biobridge and transfers VBP onto the living cell membrane via lipid rafts for surface engineering of MSCs in suspension. When compared with the membrane-modifying strategies of PEGylated phospholipids, 4F-VBP (HDL) provides a 3.86 higher linkage efficiency to obtain MSCs4F-VBP(HDL) , which can recognize and adhere to the inflammatory endothelium for efficient blood-brain barrier crossing and brain accumulation. In APPswe/PSEN1dE9 mice with Alzheimer's disease (AD), the transcriptomic analysis reveals that systemic administration of MSCs4F-VBP(HDL) can activate pathways associated with neuronal activity and diminish neuroinflammation for rewiring AD brains. This customizable HDL-mediated membrane fusogenicity platform primes MSC inflammatory brain delivery, which can be expanded to other disease treatments by simply fusing 4F with relevant ligands for living cell engineering.

Exploring energy efficiency barriers and drivers In the Portuguese water sector

While research, development, and implementation of energy efficiency measures in water and wastewater utilities are accelerating, there has been little research into the barriers and drivers to their adoption within the sector. This study presents the findings of a series of 11 semi-structured interviews conducted to Portuguese water and wastewater utilities. The results show the prioritization of quality-of-service subjects, such as reducing water losses and increasing the resilience of systems, over energy efficiency in this sector. Despite referring to financial barriers as important, the interviewees point out that the major barriers are the lack of human resources, lack of internal technical skills, and the bureaucratic public procurement processes. The main drivers highlighted in this study are the existence of awareness campaigns and dissemination of good practices, the existence of energy service companies, and the availability of funding, either public or specific financing programs with accessible rates. The results of this research can help define sector-oriented policies fostering the adoption of measures and strategies that help improve the energy performance and resilience of water and wastewater utilities worldwide.

Outstanding thermally conductive and anticorrosive polymer composite coating via a multifunctional epoxy curing agent zinc dimethacrylate

Highly thermally conductive metallic materials show great promise in thermal management field. Whereas, inherently high susceptibility of metal materials to corrosion medium would shorten service life and affect heat transfer properties of corresponding materials, thus invalidating their applicability to thermal management devices. This study solves this by preparing an epoxy composite coating with integrated high thermal conductivity (TC) and well long-term corrosion protection performance via synthesizing zinc dimethacrylate (ZDMA) as a novel multifunctional epoxy resin curing agent and designing “point-surface” heterostructure of recrystallized ZDMA nanoparticles-modified boron nitride (BN) sheet with both thermally conductive and anticorrosive functions. The findings reveal that the “double bridging effect” provided by ZDMA and well-dispersed filler result in the formation of efficient heat conduction pathways and barrier effect in the coating. The final coating (h-ZBN/Z/EP) exhibits a high TC of 2.55 W/(m·K), which is more than 11 times that of pure epoxy coating and is much higher than the TC reported for other anti-corrosion polymer coatings. Case calculation and finite element simulation show that the coating can maintain well heat transfer performance of the coated metal material compared to pure epoxy coating. Further combined with the corrosion inhibitory effect of Zn2+ ions, the low-frequency impedance of h-ZBN/Z/EP coating is still as high as 1.32 × 1011 ohm·cm2 after immersion in 3.5 wt% NaCl solution for 360 days. This ingenious strategy provides a fascinating and simple method for preparing multifunctional composite coatings used for long-term protection of heat conduction metallic materials.

High-throughput computational screening of Ti-based binary alloys as diffusion barrier layers for copper interconnects

This study utilized first-principles high-throughput computations to scrutinize the viability of Ti-W and Ti-Ru binary alloys as diffusion barrier layers for copper interconnects. By computing the formation energy, as well as constructing a convex hull phase diagram, we discerned the stability ranges for these alloys: specifically for Ti1−xWx at 0.45 < x < 0.82, and for Ti1−xRux at 0.12 < x < 0.31 and 0.87 < x < 1. It became evident that regions rich in Ti and Ru needed exclusion due to their inherent instability and diminished mechanical properties. Detailed analyses regarding structural stability, electronic structure, and mechanical properties helped confirm that Ti1−xWx at 0.45 < x < 0.82 and Ti1−xRux at 0.12 < x < 0.31 alloys offer optimal choices for efficient diffusion barriers. Moreover, the materials' mixing energy and formation energy were substantively less than 0 kJ/mol, with the alloys' convex hull energy poised within the range of 0–4 kJ/mol, thus explaining the observed superior stability of the solid solubility. Advanced screening also shed light on the previously well-studied Ti-W alloy, with Ti content between 70 % and 90 %. Interestingly, TiRu in the Ti-Ru alloys emerged as a potential area warranting further exploration. The Ti0.25W0.75 solid solution and TiRu intermetallic compound, among other alternatives probed, boasted integrative properties and thus appear as the most promising materials for diffusion barrier layers. This study delivers meaningful insights for the design and execution of high-performance diffusion barrier materials.

Oriented External Electric-Field Effects on the Activation of Aryl CO Bond in Anisole using Rh(PEP) (E=Al, B, Ga) Catalysts.

The present work reports a DFT-based mechanistic investigation of aryl C-O bond activation in anisole catalysed by a Rh-Al pincer-type complex at room temperature. The study is extended to analogues Rh-E complexes based on Group 13 elements (E=B/Ga). Our results show a preference for the heterolytic cleavage pathway over oxidative addition in the C-O bond activation. The calculated barriers range from 16 to 36 kcal/mol, following the order: E=Al<E=Ga<E=B. A strong correlation between the activation barriers and the local electric field (LEF) at the Rh metal centre for the studied Rh-E complexes was observed. Additionally, the ability of Oriented External Electric Field (OEEF) to lower the reaction barrier by applying the OEEF along the direction of electron reorganization, that is, "the reaction axis", was examined. Our results demonstrate the significant effect of applied OEEF on the aryl C-O bond activation in Rh-E systems. Furthermore, the effect of OEEF on the C-O bond activation using modified Rh-E (E=B, Al, or Ga) complexes, in which electronic structure modifications enable a more efficient barrier control by the OEEF, was showcased. Notably, applying a moderate field strength reduces the high reaction barrier for the Rh-B system by approximately 13 kcal/mol.

Distinct Organotypic Platforms Modulate Rainbow Trout (Oncorhynchus mykiss) Intestinal Cell Differentiation In Vitro.

In vitro organotypic cell-based intestinal platforms, able to faithfully recapitulate the complex functions of the organ in vivo, would be a great support to search for more sustainable feed ingredients in aquaculture. We previously demonstrated that proliferation or differentiation of rainbow trout intestinal cell lines is dictated by the culture environment. The aim of the present work was to develop a culture platform that can efficiently promote cell differentiation into mature enterocytes. We compared four options, seeding the RTpiMI cell line derived from the proximal intestine on (1) polyethylene terephthalate (PET) culture inserts ThinCert™ (TC), (2) TC coated with the solubilized basement membrane matrix Matrigel® (MM), (3) TC with the rainbow trout fibroblast cell line RTskin01 embedded within the Matrigel® matrix (MMfb), or (4) the highly porous polystyrene scaffold Alvetex® populated with the abovementioned fibroblast cell line (AV). We evaluated the presence of columnar cells with a clear polarization of brush border enzymes, the formation of an efficient barrier with a significant increase in transepithelial electrical resistance (TEER), and its ability to prevent the paracellular flux of large molecules but allow the transit of small compounds (proline and glucose) from the apical to the basolateral compartment. All parameters improved moving from the simplest (TC) through the more complex platforms. The presence of fibroblasts was particularly effective in enhancing epithelial cell differentiation within the AV platform recreating more closely the complexity of the intestinal mucosa, including the presence of extracellular vesicles between fibroblasts and epithelial cells.

Dietary Microplastic Administration during Zebrafish (Danio rerio) Development: A Comprehensive and Comparative Study between Larval and Juvenile Stages.

One of the main sources of MPs contamination in fish farms is aquafeed. The present study investigated, for the first time through a comparative approach, the effects of different-sized fluorescent MPs included in a diet intended for zebrafish (Danio rerio). A comparison based on fish developmental stage (larval vs. juvenile), exposure time, and dietary MPs' size and concentration was performed. Four experimental diets were formulated, starting from the control, by adding fluorescent polymer A (size range 1-5 µm) and B (size range 40-47 µm) at two different concentrations (50 and 500 mg/kg). Zebrafish were sampled at 20 (larval phase) and 60 dpf (juvenile stage). Whole larvae, intestine, liver and muscles of juveniles were collected for the analyses. Polymer A was absorbed at the intestinal level in both larvae and juveniles, while it was evidenced at the hepatic and muscular levels only in juveniles. Hepatic accumulation caused an increase in oxidative stress markers in juveniles, but at the same time significantly reduced the number of MPs able to reach the muscle, representing an efficient barrier against the spread of MPs. Polymer B simply transited through the gut, causing an abrasive effect and an increase in goblet cell abundance in both stages.

Hot-Electron-Induced Photochemical Properties of CdSe/ZnSe Core/Shell Quantum Dots under an Ambient Environment.

Using CdSe/ZnSe core-shell quantum dots (QDs) as a model, we systematically investigate the photochemical properties of QDs with the ZnSe shells under an ambient environment, which show almost opposite responses to either oxygen or water in comparison with CdSe/CdS core/shell QDs. While the ZnSe shells provide an efficient potential barrier for photoinduced electron transfer from the core to the surface-adsorbed oxygen, they also act as a stepping stone for hot-electron transfer directly from the ZnSe shells to oxygen. The latter process is so effective and competes favorably with ultrafast relaxation of hot electrons from the ZnSe shells to the core QDs, which can completely quench the photoluminescence (PL) with saturated adsorption of oxygen (1 bar) and initiate oxidation of the surface anion sites. Water can slowly eliminate the excess hole to neutralize the positively charged QDs, partially canceling the photochemical effects of oxygen. Alkylphosphines─through two distinctive reaction pathways with oxygen─stop the photochemical effects of oxygen and completely recover PL. With limited thickness (around two monolayers), the ZnS outer shells substantially slow down photochemical effects on CdSe/ZnSe/ZnS core/shell/shell QDs but cannot fully stop PL quenching by oxygen.