Flexible solar cells based on foldable silicon wafers with blunted edges.

Flexible solar cells have a lot of market potential for application in photovoltaics integrated into buildings and wearable electronics because they are lightweight, shockproof and self-powered. Silicon solar cells have been successfully used in large power plants. However, despite the efforts made for more than 50 years, there has been no notable progress in the development of flexible silicon solar cells because of their rigidity1-4. Here we provide a strategy for fabricating large-scale, foldable silicon wafers and manufacturing flexible solar cells. A textured crystalline silicon wafer always starts to crack at the sharp channels between surface pyramids in the marginal region of the wafer. This fact enabled us to improve the flexibility of silicon wafers by blunting the pyramidal structure in the marginal regions. This edge-blunting technique enables commercial production of large-scale (>240 cm2), high-efficiency (>24%) silicon solar cells that can be rolled similarly to a sheet of paper. The cells retain 100% of their power conversion efficiency after 1,000 side-to-side bending cycles. After being assembled into large (>10,000 cm2) flexible modules, these cells retain 99.62% of their power after thermal cycling between -70 °C and 85 °C for 120 h. Furthermore, they retain 96.03% of their power after 20 min of exposure to air flow when attached to a soft gasbag, which models wind blowing during a violent storm.

ATAD1 inhibits hepatitis C virus infection by removing the viral TA-protein NS5B from mitochondria.

ATPase family AAA domain-containing protein 1 (ATAD1) maintains mitochondrial homeostasis by removing mislocalized tail-anchored (TA) proteins from the mitochondrial outer membrane (MOM). Hepatitis C virus (HCV) infection induces mitochondrial fragmentation, and viral NS5B protein is a TA protein. Here, we investigate whether ATAD1 plays a role in regulating HCV infection. We find that HCV infection has no effect on ATAD1 expression, but knockout of ATAD1 significantly enhances HCV infection; this enhancement is suppressed by ATAD1 complementation. NS5B partially localizes to mitochondria, dependent on its transmembrane domain (TMD), and induces mitochondrial fragmentation, which is further enhanced by ATAD1 knockout. ATAD1 interacts with NS5B, dependent on its three internal domains (TMD, pore-loop 1, and pore-loop 2), and induces the proteasomal degradation of NS5B. In addition, we provide evidence that ATAD1 augments the antiviral function of MAVS upon HCV infection. Taken together, we show that the mitochondrial quality control exerted by ATAD1 can be extended to a novel antiviral function through the extraction of the viral TA-protein NS5B from the mitochondrial outer membrane.

Hippocampal excitation-inhibition balance underlies the 5-HT2C receptor in modulating depressive behaviours.

The implication of 5-hydroxytryptamine 2C receptor (5-HT2CR) in depression is a topic of debate, and the underlying mechanisms remain largely unclear. We now elucidate hippocampal excitation-inhibition (E/I) balance underlies the regulatory effects of 5-HT2CR in depression. Molecular biological analyses showed that chronic mild stress (CMS) reduced the expression of 5-HT2CR in hippocampus. We revealed that inhibition of 5-HT2CR induced depressive-like behaviors, reduced GABA release and shifted the E/I balance towards excitation in CA3 pyramidal neurons by using behavioral analyses, microdialysis coupled with mass spectrum, and electrophysiological recording. Moreover, 5-HT2CR modulated neuronal nitric oxide synthase (nNOS)-carboxy-terminal PDZ ligand of nNOS (CAPON) interaction through influencing intracellular Ca2+ release, as determined by fiber photometry and coimmunoprecipitation. Notably, disruption of nNOS-CAPON by specific small molecule compound ZLc-002 or AAV-CMV-CAPON-125C-GFP, abolished 5-HT2CR inhibition-induced depressive-like behaviors, as well as the impairment in soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly-mediated GABA vesicle release and a consequent E/I imbalance. Importantly, optogenetic inhibition of CA3 GABAergic neurons prevented the effects of AAV-CMV-CAPON-125C-GFP on depressive behaviors in the presence of 5-HT2CR antagonist. Conclusively, our findings disclose the regulatory role of 5-HT2CR in depressive-like behaviors and highlight the hippocampal nNOS-CAPON coupling-triggered E/I imbalance as a pivotal cellular event underpinning the behavioral consequences of 5-HT2CR inhibition.

Hypoxic environment promotes angiogenesis and bone bridge formation by activating Notch/RBPJ signaling pathway in HUVECs.

After epiphyseal fracture, the epiphyseal plate is prone to ischemia and hypoxia, leading to the formation of bone bridge and deformity. However, the exact mechanism controlling the bone bridge formation remains unclear. Notch/RBPJ signaling axis has been indicated to regulate angiogenesis and osteogenic differentiation. Our study aims to investigate the mechanism of bone bridge formation after epiphyseal plate injury, and to provide a theoretical basis for new therapeutic approaches to prevent the bone bridge formation. The expression of DLL4 and RBPJ was significantly up-regulated in HUVECs after ischemia and hypoxia treatment. Notch/RBPJ pathway positively regulated the osteogenic differentiation of BMSCs. HUVECs can induce osteogenic differentiation of BMSCs under ischemia and hypoxia. Notch/RBPJ pathway is involved in the regulation of the trans-epiphyseal bridge formation. Notch/RBPJ in HUVECs is associated with osteogenic differentiation of BMSCs and may participate in the regulation of the bone bridge formation across the epiphyseal plate.

Boosting the Photocatalytic Performance of g-C3N4 through MoS2 Nanotubes with the Cavity Enhancement Effect.

The development of catalysts with high photon utilization efficiency is crucial for enhancing the catalytic performance of photocatalysts. Graphitic carbon nitride (g-C3N4) is a prominent material in the field of photocatalysis. However, it still exhibits drawbacks such as low utilization of visible light and severe recombination of photogenerated carriers. To address these issues, this study employs MoS2 nanotubes (NTs) as cocatalysts and constructs MoS2 NTs/g-C3N4. The MoS2 NTs/g-C3N4 exhibits a significant cavity enhancement effect through multiple light reflections. This results in a broad spectral absorption range and high photon utilization efficiency, while also reducing the recombination of photogenerated carriers. The photocatalyst demonstrates outstanding performance in both photocatalytic hydrogen production and photodegradation of organic pollutants. Specifically, the hydrogen production rate is 1921 µmol·g-1·h-1, which is approximately 2.4 times that of g-C3N4. Furthermore, the photodegradation rate of Rhodamine B reaches 98.6% within 30 min, which is approximately three times higher than that of g-C3N4. Free radical capture experiments confirm that holes (h+) are the primary active species in photodegradation. A plausible photocatalytic mechanism for the catalyst is proposed. This study provides valuable insights into the development of heterojunction photocatalysts with high photon utilization efficiency.

Combinatorial Synthesis of Covalent Organic Framework Particles with Hierarchical Pores and Their Catalytic Application.

Precise tailoring of the aggregation state of covalent organic frameworks (COFs) to form a hierarchical porous structure is critical to their performance and applications. Here, we report a one-pot and one-step strategy of using dynamic combinatorial chemistry to construct imine-based hollow COFs containing meso- and macropores. It relies on a direct copolymerization of three or more monomers in the presence of two monofunctional competitors. The resulting particle products possess high crystallinity and hierarchical pores, including micropores around 0.93 nm, mesopores widely distributed in the range of 3.1-32 nm, and macropores at about 500 nm, while the specific surface area could be up to 748 m2·g-1, with non-micropores accounting for 60% of the specific surface area. The particles demonstrate unique advantages in the application as nanocarriers for in situ loading of Pd catalysts at 93.8% loading efficiency in the copolymerization of ethylene and carbon monoxide. The growth and assembly of the copolymer could thus be regulated to form flower-shaped particles, efficiently suppressing the fouling of the reactor. The copolymer's weight-average molecular weight and the melting temperature are also highly improved. Our method provides a facile way of fabricating COFs with hierarchical pores for advanced applications in catalysis.

Rab3A interacts with spastin to regulate neurite outgrowth in hippocampal neurons.

Investigating novel mechanisms of neurite outgrowth via cytoskeleton is critical for developing therapeutic strategies against neural disorders. Rab3A is a vesicle-related protein distributed throughout the nervous system, but the detailed mechanism related to cytoskeleton remains largely unknown. Our previous reports show that spastin serves microtubule to regulate neurite outgrowth. Here, we asked whether Rab3A could function via modulating spastin during neuronal development. The results revealed that Rab3A colocalized with spastin in cultured hippocampal neurons. Immunoprecipitation assays showed that Rab3A physically interacted with spastin in rat brain lysates. Rab3A overexpression significantly induced spastin degradation; this effect was reversed by leupeptin- or MG-132- administration, suggesting the lysosomal and ubiquitin-mediated degradation system. Immunofluorescence staining further confirmed that Rab3A and spastin immune-colocalized with the lysosome marker lysotracker. In COS7 cells, Rab3A overexpression significantly downregulated spastin expression and abolished the spastin-mediated microtubule severing. Furthermore, overexpression inhibited while genetic knockdown of Rab3A promoted neurite outgrowth. However, this inhibitory effect on neurite outgrowth in hippocampal neurons could be reversed via co-transfection of spastin, indicating that Rab3A functions via its interaction protein spastin. In general, our data identify an interaction between Rab3A and spastin, and this interaction affects the protein stability of spastin and eliminates its microtubule severing function, thereby modulating neurite outgrowth.

Enhanced Photoinduced Carrier Separation in Fe-MOF-525/CdS for Photocatalytic Hydrogen Evolution: Improved Catalytic Dynamics with Specific Active Sites.

Single-atom metal-anchored porphyrin-based metal-organic frameworks (MOFs) have shown excellent light absorption, catalytic sites, and high stability during photocatalytic reactions, while there are still challenges for facile assembly with quantum dots to enhance catalytic dynamics. Herein, a kind of Fe single atom-doped MOF material (Fe-MOF-525) was ball milled with CdS in a proper ratio through Fe-N4 and Fe-N-C bonding, which showed the enhanced photoinduced carrier separation ability. As a result, extended light absorption ranges of CdS/Fe-MOF-5252.3 induced the promotion of the photocatalytic hydrogen (H2) value (3638.6 µmol g-1 h-1), which was 7.2 and 2.3 times higher than those of Fe-MOF-525 and CdS. In this work, the facile synthetic technique, specific active sites, and enhanced catalytic dynamics in the composite highlight the future research on MOF-based heterojunctions and their potential photocatalysis applications..

Exposure to Butylparaben Induces Craniofacial Bone Developmental Toxicity in Zebrafish (Danio rerio) Embryos.

Butylparaben (BuP) is a common antibacterial preservative utilized extensively in food, medical supplies, cosmetics, and personal care products. The current study reports the use of Zebrafish (Danio rerio) embryos to investigate potential developmental toxicity caused by exposure to BuP. The development of Neural crest cells (NCCs) is highly active during gastrulation in Zebrafish embryos. Thus, we utilized 0.5 mg/L, 0.75 mg/L, and 1 mg/L BuP solutions, respectively, in accordance with the international safety standard dosage. We observed severe craniofacial cartilage deformities, periocular edema, cardiac dysplasia, and delayed otolith development in the Zebrafish larvae 5 days after exposure. The oxidative stress response was significantly enhanced. In addition, the biochemical analysis revealed that the activities of catalase (CAT) and superoxide dismutase (SOD) were significantly reduced relative to the control group, whereas the concentration of malondialdehyde (MDA) was significantly elevated. Furthermore, ALP activity, a marker of osteoblast activity, was also reduced. Moreover, the RT-qPCR results indicated that the expression of chondrocyte marker genes sox9a, sox9b, and col2a1a was down-regulated. In addition, the morphology of maxillofacial chondrocytes was altered in Zebrafish larvae, and the proliferation of cranial NCCs was inhibited. Accordingly, our findings indicate that strong oxidative stress induced by BuP inhibits the proliferation of NCCs in larval Zebrafish, leading to craniofacial deformities.

Microbial pathways driving stable soil organic carbon change in abandoned Moso bamboo forests in southeast China.

Mineral-associated organic carbon (MOC) is a stable component of the soil carbon (C) pool, critical to realize carbon sequestration and coping with climate change. Many Moso bamboo (Phyllostachys edulis) forests in subtropical and tropical areas that used to be intensively managed have been left unmanaged. Still, studies on MOC changes occurring during the transition from intensive management to unmanagement are lacking. Besides, the understanding of the role of microorganisms in MOC accumulation is far from satisfactory. Based on the combination of field investigation and laboratory analysis of 40 Moso bamboo forest sampling plots with different unmanaged chronosequence's in southeast China, we observed the MOC content in Moso bamboo forests left unmanaged for 2-5 years had decreased, whereas that in forests left unmanaged for 11-14 years had increased compared with that in intensively managed forests. Specifically, the MOC contents in forests left unmanaged for 11-14 years were significantly higher than in those under intensive management or unmanaged for 2-5 years. Moreover, we found that microorganisms drove MOC change through two different pathways: (i) more microorganisms led to more soil nutrients, which led to more amino sugars, ultimately resulting in the accumulation of MOC, and (ii) microorganisms promoted the accumulation of MOC by influencing the content of metal oxides (poorly crystalline aluminum oxides and free aluminum oxides). We believe that ignoring the interaction between microorganisms and metal oxides may lead to uncertainty in evaluating the relative contribution of microbial residues to MOC.

Preparation and Reactivity Study of a Versatile Trifluoromethylthiolating Agent: S-Trifluoromethyl Trifluoromethanesulfonothioate (TTST).

A novel, air and thermally stable, yet highly reactive trifluoromethylthiolating reagent, CF3 SO2 SCF3 (1), was prepared easily in one step from commercially inexpensive CF3 SO2 Na and Tf2 O. 1 is a highly versatile and atom-efficient reagent that can generate one equivalent of CF3 S+ , two equivalents of CF3 S- , or a combination of CF3 S⋅/CF3 ⋅ species. Many high-yielding CF3 S reactions of C, O, S, and N-nucleophiles were achieved, including the simple-step preparations of many reported CF3 S reagents. 1 delivered a hitherto hard-to-synthesize ArOSCF3 that was followed by a novel CF3 SII -rearrangement. Through Cu or TDAE/Ph3 P combinations, 1 generated two equivalents of CF3 S anion species, and the photo-catalyzed reactions of alkenes with 1 provided CF3 /CF3 S-containing products in high atom-efficiency.

Computational adaptive optics for high-resolution non-line-of-sight imaging.

Non-line-of-sight (NLOS) imaging has aroused great interest during the past few years, by providing a unique solution for the observation of hidden objects behind obstructions or scattering media. As such, NLOS imaging may facilitate broad applications in autonomous driving, remote sensing, and medical diagnosis. However, existing NLOS frameworks suffer from severe degradation of resolution and signal-to-noise ratio (SNR) due to aberrations induced by scattering media and system misalignment, restricting its practical applications. This paper proposes a computational adaptive optics (CAO) method for NLOS imaging to correct optical aberrations in post-processing without the requirement of any hardware modifications. We demonstrate the effectiveness of CAO with a confocal NLOS imaging system in Terahertz (THz) band by imaging different samples behind occlusions for both low- and high-order aberrations. With appropriate metrics used for iterative CAO in post-processing, both the resolution and SNR can be increased by several times without reducing the data acquisition speed.

The impact of different rotation regime on the soil bacterial and fungal communities in an intensively managed agricultural region.

The continuous wheat-maize planting has led to the increase in epidemic frequency of wheat diseases under climate change. Analyzation of the soil microbial composition in different rotation crops is essential to select alternative rotation regime. This study investigated the bacterial and fungal community abundance and composition, and potential microbe-microbe interactions in three rotations, including wheat-maize → spring maize (WMFS), wheat-soybean (WS) and continuous wheat-maize (WM) planting. The results revealed that there were 110, 156, and 195 bacterial, and 17, 8, and 15 fungal operational taxonomic units respectively enriched by WMFS, WS, and WM. WM increased the relative abundance of Actinobacteria and α-Proteobacteria in wheat, and the relative abundance and copy number of genus Fusarium in maize. WMFS and WS could decrease the abundance of Fusarium in summer-crop across the growth stages and in wheat at elongation. WS also increased the copy number of ammonia-oxidizing bacteria in wheat at flowering and harvest. Network analysis revealed that WM resulted in simple and isolated wheat network with small modules dominating and none Nitrospirae and ß-Proteobacteria in the main modules. WS formed interconnected and intricate wheat network with the maximum number of large modules and module connectors. Under WS, positive correlation between antagonistic Streptomyces (Actinobacteria) and genus Fusarium was found in wheat. Soil physicochemical properties explained the majority of the variation in bacterial and fungal ß-diversity in wheat (P < 0.01). Rotation regime switching from WM to WMFS and WS may effectively damp the risk of wheat disease and maintain the wheat yield in intensive cereal production.

Oxyfluorfen induces hepatotoxicity through lipo-sugar accumulation and inflammation in zebrafish (Danio rerio).

Oxyfluorfen (OXY) is widely used in agriculture as a herbicide, resulting in its continuous accumulation in the environment. The presence of OXY can be detected in soil and rivers. However, until now, the potential toxicity of OXY to aquatic organisms has not been evaluated. In this study, zebrafish was used as a model animal to evaluate OXY-induced liver toxicity. The study found that 0.25, 0.5, and 1 mg/L of OXY affected the early development of zebrafish and severely damaged the lipid and sugar metabolism in the liver of zebrafish larvae. Furthermore, a metabolic function disorder caused liver damage. OXY also caused inflammation by upregulating the inflammatory factors IL-6, IL-8, and TNF-α, and activated the apoptotic pathway to inhibit hepatocyte proliferation, resulting in zebrafish liver toxicity. Our research showed that OXY had certain toxic effects on zebrafish development and liver and could cause potential harm to other aquatic organisms and humans.

Combination of biodegradation and fenton process for efficient removal of PDM/ZnO.

In the present study, an investigation was conducted on the removal of polydiallyldimethylammonium chloride-acrylic-acrylamide-hydroxyethyl acrylate/ZnO nanocomposites (PDM/ZnO) through biodegradation and Fenton process coupled treatments. As revealed from the results of the chemical oxygen demand, the total organic carbon, the biochemical oxygen demand and the CO2 production analysis, PDM/ZnO could be partially biodegraded. The optimal initial pH, the mixed liquid suspended solids concentration and additional carbon source (glucose) dosage in the biodegradation were 7.0, 4.0 g/L and 1.0 g/L, respectively. On the whole, NaCl, the coexisted metal cations (Cu2+, Zn2+ and Cr3+) and additional NH4Cl inhibited the biodegradation of PDM/ZnO. PDM/ZnO was suggested to adversely affect on microbial community structure and activity. Optimum conditions for Fenton treatment were 50 mg/L Fe2+, 20 mL/L H2O2 and pH 2.0. Biodegradation showed that 64% of PDM/ZnO was removed. Besides, the combination of Fenton post-treatment could achieve an over 97% removal of PDM/ZnO. Thus, Fenton process combined biodegradation pre-treatment can act as an effective method to remove PDM/ZnO.

Self-Sustaining Fluorination of Active Methylene Compounds and High-Yielding Fluorination of Highly Basic Aryl and Alkenyl Lithium Species with a Sterically Hindered N-Fluorosulfonamide Reagent.

Fluorination of carbanions is pivotal for the synthesis of fluorinated compounds, but the current N-F fluorinating agents have significant drawbacks due to many reactive locations that surround the reactive N-F site. By developing a sterically hindered N-fluorosulfonamide reagent, namely N-fluoro-N-(tert-butyl)-tert-butanesulfonamide (NFBB), we discovered a conceptually novel base-catalyzed, self-sustaining fluorination of active methylene compounds and achieved the high-yielding fluorination of the hitherto difficult highly basic (hetero)aryl and alkenyl lithium species. In the former, the mild and high yield fluorination of active methylene compounds exhibited wide functional group tolerance and its novel catalytic fluorination-deprotonation cycle mechanism was demonstrated by deuterium-tracing experiments. In the latter, NFBB reacted with a variety of highly basic (hetero)aryl and alkenyl lithium species to provide the desired fluoro (hetero)arenes and alkenes in unprecedented high or quantitative yields.

Gold (I/III)-Catalyzed Trifluoromethylthiolation and Trifluoromethylselenolation of Organohalides.

The first C-SCF3 /SeCF3 cross-coupling reactions using gold redox catalysis [(MeDalphos)AuCl], AgSCF3 or Me4 NSeCF3 , and organohalides as substrates are reported. The new methodology enables a one-stop shop synthesis of aryl/alkenyl/alkynyl trifluoromethylthio- and selenoethers with a broad substrate scope (>60 examples with up to 97 % isolated yield). The method is scalable, and its robustness is evidenced by the late-stage functionalization of various bioactive molecules, which makes this reaction an attractive alternative in the synthesis of trifluoromethylthio- and selenoethers for pharmaceutical and agrochemical research and development.

Toward Covalent Organic Framework Metastructures.

The bottom-up assembly of periodically ordered structures provides a scalable way for producing metastructured materials with exotic optical and mechanical properties. However, direct self-assembly of small molecules into such metastructures beyond the nanoscale remains an unresolved issue. Here we demonstrate that metastructured assemblies of two-dimensional (2D) polymers, specifically 2D covalent organic frameworks (COFs), can be directly synthesized in solution. We applied 2D COF monomer polycondensation to prepare flower-shaped particles consisting of highly crystalline "petals" with sizes larger than 20 µm. The petal comprises periodically arranged COF nanoflake units with tunable lengths of 490-850 nm, thicknesses about 20 nm, interflake spacing around 14 nm, and Hermans orientation factors up to 0.998. Such a metastructure is mechanically robust and remains almost intact even after full pyrolysis at 900 °C. It also demonstrates unique birefringence and polarization-dependent resonances under visible-near-infrared light not observed in its constituents, 2D COF polycrystals, and with well-defined nanopores of 1.8 nm and the high surface area of 1576 m2/g. Such metastructured particles with nanopores are well-suited as novel particulate optical devices for collecting and storing information about their surroundings that can be easily read out by polarization imaging with high sensitivity, as demonstrated by their explosive detection and anticounterfeiting applications. Self-assembly of 2D polymers into metastructures may become an important method for developing functional materials with unprecedented properties and extensive applications.

Hydrogenative Ring-Rearrangement of Furfural to Cyclopentanone over Pd/UiO-66-NO2 with Tunable Missing-Linker Defects.

Upgrading furfural (FAL) to cyclopentanone (CPO) is of great importance for the synthesis of high-value chemicals and biomass utilization. The hydrogenative ring-rearrangement of FAL is catalyzed by metal-acid bifunctional catalysts. The Lewis acidity is a key factor in promoting the rearrangement of furan rings and achieving a high selectivity to CPO. In this work, highly dispersed Pd nanoparticles were successfully encapsulated into the cavities of a Zr based MOF, UiO-66-NO2, by impregnation using a double-solvent method (DSM) followed by H2 reduction. The obtained Pd/UiO-66-NO2 catalyst showed a significantly better catalytic performance in the aforementioned reaction than the Pd/UiO-66 catalyst due to the higher Lewis acidity of the support. Moreover, by using a thermal treatment. The Lewis acidity can be further increased through the creating of missing-linker defects. The resulting defective Pd/UiO-66-NO2 exhibited the highest CPO selectivity and FAL conversion of 96.6% and 98.9%, respectively. In addition, the catalyst was able to maintain a high activity and stability after four consecutive runs. The current study not only provides an efficient catalytic reaction system for the hydrogenative ring-rearrangement of furfural to cyclopentanone but also emphasizes the importance of defect sites.

Development of N-F fluorinating agents and their fluorinations: Historical perspective.

This review deals with the historical development of all N-F fluorinating agents developed so far. The unique properties of fluorine make fluorinated organic compounds attractive in many research areas and therefore fluorinating agents are important. N-F agents have proven useful by virtue of their easy handling. This reagent class includes many types of N-F compounds: perfluoro-N-fluoropiperidine, N-fluoro-2-pyridone, N-fluoro-N-alkylarenesulfonamides, N-fluoropyridinium salts and derivatives, N-fluoroquinuclidium salts, N-fluoro-trifluoromethanesulfonimide, N-fluoro-sultams, N-fluoro-benzothiazole dioxides, N-fluoro-lactams, N-fluoro-o-benzenedisulfonimide, N-fluoro-benzenesulfonimide, 1-alkyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane salts, N-fluoropyridinium-2-sulfonate derivatives, 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane salts, N-fluorodinitroimidazole, N-fluoro-trichloro-1,3,5-triazinium salt, N-F ethano-Tröger's base derivatives, N-fluoro-methanesulfonimide, N-fluoro-N-arylarenesulfonamides, bisN-F salts such as N,N'-difluorobipyridinium salts and N,N'-difluoro-1,4-diazoniabicyclo[2.2.2]octane salts, and their many derivatives and analogs, including chiral N-F reagents such as optically active N-fluoro-sultam derivatives, N-fluoro-alkaloid derivatives, DABCO-based N-F derivatives, and N-F binaphthyldisulfonimides. The synthesis and reactions of these reagents are described chronologically and the review also discusses the relative fluorination power of each reagent and their mechanisms chronicling developments from a historical perspective.