We investigated the mechanism, whereby tumor necrosis factor‐like ligand 1A (TL1A) mediates the A1 differentiation of astrocytes in postoperative cognitive dysfunction (POCD).The cognitive and behavioral abilities of mice were assessed by Morris water maze and open field tests, while the levels of key A1 and A2 astrocyte factors were detected by RT‐qPCR. Immunohistochemical (IHC) staining was used to examine the expression of GFAP, western blot was used to assay the levels of related proteins, and enzyme‐linked immunosorbent assay (ELISA) was used to detect the levels of inflammatory cytokines.The results showed that TL1A could promote the progression of cognitive dysfunction in mice. Astrocytes differentiated into A1 phenotype, while unobvious changes were noted in astrocyte A2 biomarkers. Knockout of NLRP3 or intervention with NLRP3 inhibitor could inhibit the effect of TL1A, improving the cognitive dysfunction and suppressing the A1 differentiation.Our results demonstrate that TL1A plays an important role in POCD in mice, which promotes the A1 differentiation of astrocytes through NLRP3, thereby exacerbating the progression of cognitive dysfunction. We find that TL1A can promote the A1 differentiation of RAs via NLRP3 while aggravating the POCD. RAs‐A1 is a major pathological factor in the progression of POCD, while TL1A is an important cytokine in such progression. We provide a new reference for the pathological study of POCD. It has been found to act importantly in inflammatory bowel disease, neuroimmunity, and neuroinflammation.22.1em1Cya, KO) mice were purchased from Cyagen Biosciences, which were fed and watered freely in the Laboratory Animal Center of Jiaxing University. The mouse experiments complied with relevant regulations on animal ethics and welfare, and the experimental protocol was approved by the Ethics Committee.Wild‐type (WT) and NLRP3‐knockout . Mice in the Normal group underwent sham operation without splenectomy, while those in the POCD and POCD + TL1A groups underwent operation. The OCD + TL1A mice were intraperitoneally injected with recombinant TL1A cytokine (Abcam) at 5 ng/daily for 5 days prior to surgery.In Experiment 1, the WT mice were divided into three groups, namely, Normal, POCD, and POCD + TL1A (n = 10 per group). Mice in the WT and KO groups underwent sham operation without splenectomy, while those in the remaining two groups underwent operation without other drug intervention. The mice were fed and lived in the same environment.In Experiment 2, the WT and KO mice were divided into WT, KO, TL1A + WT‐POCD, and TL1A + KO‐POCD groups (n = 10 per group). Mice in the Normal, POCD, and POCD + TL1A groups were treated in the same way as in Experiment 1, while those in the POCD + TL1A + MCC950 group were given intragastric administration of 10 mg/kg MCC950 (NLRP3 specific inhibitor) once daily in addition to intrabitoneal injection of 5 ng of TL1A since 5 days before surgery, which were administered synchronously with TL1A.In Experiment 3, the WT mice were divided into four groups, namely, Normal, POCD, POCD + TL1A, and POCD + TL1A + MCC950 , and the cognitive ability changes in mice were dynamically observed.2.3The OFT explores the behaviors and activities of mice by analyzing the distance or time of their movements in different parts of the open field, such as overall, central, and peripheral areas. The length, width, and height of the open field were 90, 90, and 15 cm, respectively. During the test, the mice were placed gently in the field center, and their movement distance and residence time in the central area within 5 min were monitored via a video tracking software. Prior to testing the next mouse, the open field was cleaned with 70% ethanol to avoid influence from the residual urine or fecal odor of the previous mouse. The test environment was kept quiet to prevent disturbance to the mice.2.4The expression levels of inflammatory cytokines IL‐1β, IL‐6, and TNF‐α were assayed. In the animal experiment, the mouse brain tissues were isolated, cleaned twice with PBS, removed of blood vessels, membranes and other tissues, pulverized with liquid nitrogen, and then lysed on ice for 30 min with 1 mL of NP‐40 lysis buffer (Beyotime Biotechnology). The supernatant protein solutions were collected for assays. In the cell experiment, the culture medium was collected after treatment of BV2 cells, which was then centrifuged at 3000 rpm for 30 min and cryopreserved at −80°C. The cytokine levels were detected as per the protocol of the ELISA kit (Jiancheng Bioengineering Institute), and calculated by the standard curve method. The results were expressed in pg/mL.2.5We detected the mRNA levels of A1 biomarkers  and A2 biomarkers  in brain tissues and RAs. Table RT‐qPCR: Total RNAs were isolated from cells using TRIzol reagent (Invitrogen), which were subjected to first‐strand cDNA synthesis using a reverse transcription system (Roche) following the manufacturer's protocol. Next, PCR analysis was performed using the 7900 real‐time PCR system  and the SYBR Green PCR Master Mix (Roche) following the manufacturers' instructions to obtain cDNA. UC was used as a control, and the ΔΔCT method was used to present the relative RNA expression.2.6After the behavioral experiment, the mice were killed, and their brain tissues were perfused. The brain tissues were isolated, fixed in 4% paraformaldehyde, dehydrated with 15% and 30% sucrose solutions, embedded in OCT, serially sectioned at a thickness of 8 μm, and cryopreserved at −20°C. Next, the tissue sections were washed in PBS, blocked with 5% serum for 30 min, and then incubated overnight using the GFAP monoclonal antibody  at 4°C. Following three time washing in PBS, visualization was performed via the peroxidase substrate kit (Abcam), and the expression levels of GFAP were observed microscopically, We mainly observe the level of GFAP in cortical tissue.2.7The liquid nitrogen homogenates of mouse brain tissues were used for tissue protein detection. In the cell experiment, the suspended and adherent cells were collected after treatment, which were then washed with PBS for subsequent use. The tissue homogenate cells were lysed on ice for 30 min using 1.0 mL of precooled RIPA lysis buffer (Beyotime Biotechnology), followed by protein quantification via BCA assay and adjustment of protein concentrations. After denaturation at 100°C, the protein samples were electrophoresed and transferred onto the PVDF membranes. Thereafter, the membranes were washed in TBST and incubated for 2 h with horseradish peroxidase‐conjugated secondary antibody (Abcam). Image Pro‐Plus 6.0 was used to analyze the optical density (OD), and the results were presented as OD value comparisons between the target protein and the internal GAPDH reference.2.8The primary reactive astrocytes (RAs) of mice were used for experiments. The RAs of WT and KO mice were separated. The whole brains of newborn mice aged 1–3 days were harvested, disinfected with 75% ethanol, and then the hippocampus tissues were cut into small pieces under a dissecting microscope. After digestion of the tissue pieces with 0.25% trypsin, the digestion was terminated with complete DMEM and cells were separated by filtration through a sterile 100‐μm screen. The culture medium was replaced 12–18 h later, and the cells were passaged once every 3 days, and subsequently prepared on the 1% polylysine‐coated plates.RAs‐A1 induction conditions: stimulation with TNF‐α (30 ng/mL), IL‐1α (3 ng/mL), and C1q (400 μg/mL) for 24 h.In Experiment 1, the RAs isolated from WT mice were used, which were divided into Control, A1, and A1 + TL1A groups. In the A1 group, A1 differentiation was performed according to the induction conditions of RAS‐A1, while in the A1 + TL1A group, 10 ng/mL TL1A was added for the cell treatment.NLRP3−/−‐A1 + TL1A group. In the A1 + TL1A group, 10 ng/mL TL1A was also added for the cell treatment.In Experiment 2, the RAs isolated from WT mice were divided into Control, A1, and A1 + TL1A groups, whereas the RAs isolated from KO mice were assigned to the 2.9n, mean ± SEM). The SPSS 17.0 software was employed for data analysis and processing. After homogeneity test of variance, two independent sample t‐test was used for comparison between two groups, while one‐way ANOVA was conducted for comparison among three groups, and the subsequent pairwise comparison between groups was completed by LSD. All the above tests were two‐sided, and a difference of p < 0.05 signified statistical significance.The measurement data were expressed as  and A2 biomarkers  were detected. The results showed significantly upregulated mRNA levels of A1 biomarkers in POCD, which were higher than those in Normal. TL1A could further upregulate these mRNA levels Figure . Contras3.3The Morris water maze test revealed absence of obvious cognitive dysfunction in WT and KO mice, proving that the NLRP3 knockout did not affect POCD significantly. Obvious cognitive dysfunction was noted in the TL1A + WT‐POCD and TL1A + KO‐POCD mice, with the TL1A + KO‐POCD mice being less dysfunctional than the TL1A + WT‐POCD mice, as manifested by shortened escape latency, prolonged total movement distance and navigation time, as well as increased number of platform crossings Figure . OFT res3.4The assay results of A1 RA biomarkers showed that the NLRP3 knockout could lower the mRNA levels. Compared to the TL1A + WT‐POCD group, the mRNA levels of Serping1, Ggta1, C3, Psmb8, Srgn, and Amigo2 declined in the TL1A + KO‐POCD group Figure . The A2 3.5We used MCC950, an NLRP3 inhibitor, to block the action of NLRP3, and the results showed that MCC950 could antagonize the action of TL1A and inhibit the RAs‐A1 differentiation. Compared to the POCD‐TL1A group, the A1 RA mRNA levels in the POCD‐TL1A + MCC950 group decreased significantly Figure , while t3.6Reactive astrocytes (RAs) were successfully differentiated into the A1 phenotype so that the A1 RA mRNA levels were significantly upregulated, which were higher than those in the Control group. TL1A could promote the RAs‐A1 differentiation and elevate the mRNA levels Figure . Contras3.7NLRP3−/−‐A1 + TL1A group, leading to significantly lower mRNA levels of A1 biomarkers than those in the A1 + TL1A group  is a common complication following anesthesia, especially among elderly patients aged 65+ years and those who have undergone major surgery, with high morbidity and certain mortality.Studies have found that TL1A, a member of tumor necrosis family, is involved in the regulation of tumor, inflammation, and immunity, which exerts its role primarily via the DR3 ligand,5We find that TL1A can promote the A1 differentiation of RAs via NLRP3 while aggravating the POCD. RAs‐A1 is a major pathological factor in the progression of POCD, while TL1A is an important cytokine in such progression. We provide a new reference for the pathological study of POCD.Genghuan Wang and Yingcong Lin are mainly responsible for the operation of the experiment, the acquisition of relevant data, and the statistical distraction of the data; JianShen, Liping Zhai are mainly responsible for literature review, project coordination, partial data analysis, and article writing; Genghuan Wang and Qiaobing Guan are mainly responsible for project development, financial support, overall project proposal, and experimental design.All authors approval published the article.


An ECC‐induced increase in titin‐based stiffness may contribute to the increased PFE. These results suggest that skeletal muscle is endowed with a force potentiation system that can attenuate ECC‐induced force reductions.The aim of this study was to elucidate the effects of eccentric contraction (ECC) on force enhancement in rat fast‐twitch skeletal muscle. Gastrocnemius (GAS) muscles were subjected to 200 ECCs in situ by electrical stimulation. Immediately before and after the stimulation, isometric torque produced by ankle flexion was measured at an ankle angle of 90°. After the second torque measurement, the superficial regions of the muscles were dissected and subjected to biochemical and skinned fiber analysis. ECC did not induce changes in the amount of degraded titin. After ECC, isometric torques in the GAS muscles were markedly reduced, especially at low stimulation frequency. ECC increased passive torque in whole muscle and passive force in skinned fibers. Passive force enhancement and the ratio of passive force to the maximal Ca Active force is generated by ATP‐driven interactions between myosin and actin filaments, whereas passive force is generated by elastic elements in stretched muscles. Titin is a giant protein with a molecular mass of 3–4 MDa that extends from the Z‐disk to the M‐band of the sarcomere. The I‐band region of titin contains flexible domains (immunoglobulin and PEVK domains), which are thought to contribute to passive force at long sarcomere lengths (SLs) , that is, residual force enhancement (RFE) and passive force enhancement (PFE). RFE is defined as an increase in active isometric force of a muscle after active stretch, compared with the corresponding (same length and same activation) active isometric force of a muscle whose length is not changed during activation. PFE is defined as an increase in passive force of a muscle after active stretch, compared to the corresponding (same length) passive force of a muscle Herzog, . FEs havEccentric contraction (ECC) is a contraction, in which skeletal muscles are stretched while contracting. It occurs when a force applied to the muscle exceeds the instantaneous force generated by the muscle itself. In a recent study from our laboratory  muscles partially support our hypothesis.22.1−1), midazolam (2.0 mg⋅kg body wt−1), and butorphanol (2.5 mg⋅kg body wt−1) was intraperitoneally administered for anesthesia. At the end of the experiments, the rats were euthanized with an overdose of isoflurane, followed by cervical dislocation. All procedures performed were approved by the Animal Care Committee of Hiroshima University.Eight male Wistar rats (10–11‐week‐old) were used in this study . The animals were provided water and standard chow  ad libitum and housed in a thermally controlled room at 20–24°C with a 12:12‐h light–dark cycle. A mixture of medetomidine . The knee and ankle were stabilized on the foot holder with a strap. The knee angle was maintained at 90° during the experiment. The muscle was stimulated every 4 s for 100 cycles using a 1‐s train of 1‐ms pulse at 80 Hz. During the stimulation, the foot was dorsiflexed by servomotor from 110° to 50° ankle angle at 60° sIn steps 1 and 2, the torque at 90° ankle angle at rest was set to 0 mN·m. Muscles from the contralateral limb were used as rested controls to compare with muscles subjected to ECC  for amount of degraded titin, passive force in skinned fibers, RFE, and PFE. The rested and ECC muscles were excised after passive torque measurements. Mechanically skinned fibers were prepared from a part of the superficial region of the lateral muscle, and the superficial region of the medial muscle was stored at −80°C for biochemical analysis. The experiments were conducted in a room controlled at 25°C.2.3−1) of an ice‐cold buffer containing 8 M urea, 2 M thiourea, 10 mM EGTA, 10 mM EDTA, 0.2 mM phenylmethanesulfonyl fluoride, 1.4 μM pepstatin A, 2.2 μM leupeptin, 0.83 mM benzamidine, and 0.13% 2‐mercaptoethanol (vol.⋅vol.−1). The protein content of the homogenate was determined using the Bradford assay with bovine serum albumin as the standard  were homogenized in 9 vol. (vol.⋅mass2.42.4.12+ activation (max Ca2+) solution consisted of (in mM) 36 Na+, 126 K+, 90 HEPES, 8 ATPtotal, 10 creatine phosphate, 1 Mg2+free, 49.5 Ca‐EGTA, and 0.5 EGTAfree and had a pH of 7.09–7.11 (pCa = ∼4.7). The relaxation solution was similar to the max Ca2+ solution, but with 49.5 mM Ca‐EGTA replaced by 49.5 mM EGTA (pCa >9). Mechanically skinned fibers were prepared from the excised GAS muscle as previously described in detail .Step 3: The fiber was immersed into the max Ca2+‐activated force (max Ca2+ force) and the passive force after deactivation in step 4 were termed maximal force (M) 1 and passive force (P) 1, respectively.Step 4: After reaching the maximal force, the fiber was immersed into the relaxation solution (deactivation). The maximal CaStep 5: The SL was shortened to 2.4 μm.2+ solution.Step 6: The fiber was immersed in the max Ca2+ solution. The max Ca2+ force in step 7 was termed M2.Step 7: The SL was stretched to 3.2 μm in the max CaStep 8: The fiber was immersed in the relaxation solution 20 s after stretching. The passive force after deactivation in step 8 was termed P2.To evaluate RFE and PFE, the skinned fibers were treated as follows Figure .Step 1:2+ solution often resulted in broken skinned fibers. M2 was then defined as the force level reached 20 s after the active stretch. Forces were normalized to the cross‐sectional area. The differences between M1 and M2 and between P1 and P2 are termed RFE and PFE, respectively.In step 6, the diffraction pattern produced by the laser beam sometimes disappeared or became blurred. In this case, the fiber was replaced in the relaxation solution and a fiber length difference in between 2.4‐μm and 3.2‐μm SL was measured in each fiber, using the manipulator. Based on the fiber length difference, the SL of the activating fiber was then adjusted to 3.2 μm. Our preliminary experiment demonstrated that excessively long immersion (more than ∼40 s) to the max Ca2.5t‐test, or Student's paired t‐test were used to determine the effects of ECC, stimulation frequency, ankle angle, SL, and/or active stretch as appropriate . The Holm–Sidak method was used for post hoc analysis when significant differences were detected in the two‐way repeated ANOVA. The acceptable level of significance was set at p < 0.05 .Data are presented as mean + SD. Two‐way ANOVA, two‐way repeated ANOVA, Student's 33.1There was a significant interaction between ECC and stimulation frequencies for isometric torque Figure . ECC ind3.22+‐regulated protease)  were lower in ECC than in rested fibers and that M2 was greater than M1. No differences in Δ max Ca2+ force  was calculated. There was a significant interaction between ECC and active stretch of the SL for these variables Figure . ECC res4In this study, we investigated the effects of ECC on FEs. Our previous study has indicated that ECC can induce an increase in passive force . It is well known that exercise training that includes a substantial ECC induces a greater activation of the genes responsible for muscle remodeling than other types of training  at a long SL in ECC than in rested muscle. Stimulation‐induced force in situ in ECC muscle was more depressed, compared with the max Ca2+ force in ECC fiber. The reduced force in ECC muscle will be ascribable to decreased Ca2+ release of the sarcoplasmic reticulum and impaired function of the myofibril, although the former is a predominant cause  behind FEs in further studies.J.S. and M.W. conceived and designed the research; performed experiments; analyzed the data; interpreted the results of experiments; prepared the figures; drafted the manuscript; edited and revised manuscript; approved the final version of the manuscript.This study was supported by the Grants‐in‐Aid for Scientific Research of Japan .The authors declare no conflict of interest.


C. nitida) genotypes within self, single and double hybrid crosses and to determine heterosis pattern in the resulting hybrids for sexual compatibility and key nut yield and quality traits. Crosses among kola genotypes from three field gene banks  and one advanced germplasm (Bunso progeny) in Ghana were evaluated along their parents for sexual compatibility, nut yield and nut quality. Data were collected on pod set, pseudo-pod set, pod weight, number of nuts per pod, nut weight, brix, potential alcohol and nut firmness. Significant (P < 0.001) differential pod set was observed within Bunso progeny, JX1, GX1 and MX2 crosses; while pseudo-pod set differed only within JX1 and MX2 crosses (P < 0.001). Very large prevalence of mid-parent, heterobeltiosis, and economic heterosis was observed for sexual compatibility, outturn and brix for the single and double hybrid crosses. Heterosis was prominent among the double hybrid crosses as compared to the single hybrid crosses suggesting that recurrent selection of compatible varieties from advanced generations could result in genetic gain in kola improvement. The top five crosses with best heterosis for sexual compatibility and an appreciable positive heterosis for outturn and brix were B1/11 × B1/71 × B1/157 × B1/149, B1/11 × B1/71 × B1/296 × B1/177, GX1/46 × GX1/33 × B1/212 × B1/236, JX1/90 × JX1/51 and JX1/51 × JX1/36. These materials could serve as sources of beneficial alleles for improving Ghanaian kola hybrids and populations for yield and sexual compatibility.Sexual incompatibility among kola genotypes accounted for over 50% yield loss. Compatible and high yielding varieties are in demand to develop commercial orchards. The objective of this study was to assess self-compatibility and cross-compatibility of kola ( Cola nitida and Cola acuminata, native to the warm and humid regions of tropical West Africa4 and with chromosome numbers 2n = 40, are of commercial importance as both species are cultivated for their edible nuts (kola nuts)5.The genus Cola  is made up of evergreen tropical and sub-tropical fruit crops7. Kola seed has nutritional, cultural, cosmetic and pharmaceutical interests9. Kola nuts are chewed to encourage salivation, to keep awake11 and for traditional rites like marriages and naming ceremonies14. Kola nuts are used in confectionary industries as active ingredients in beverages and pharmaceuticals15. Beverage companies use kola due to the high caffeine, 1.84–2.56%16 content of the nuts. Thus, kola nuts are greatly used for the manufacture of energy drinks17. Kola nuts are also major source of bioactive compounds and are regarded as the future gold mine of plant therapy21. The genus Cola has long been involved in Ayurvedic preparations which is based on the idea of herbal treatment and other natural therapies to treat various ailments and disorders. The genus has received the attention of pharmaceutical industries due to the presence of bioactive molecules like Hydroxy Citric Acid (HCA), oleic acid, flavonoids and theobromine which has immense remedial qualities23.The nuts are also rich in palmitic and oleic acids which are known to maintain good skin; consequently they are used in the production of cosmetic products such as soaps24, while the red coloured ones are regarded as a rich source of red pigments in the plant kingdom26. The pigments that give fresh foods their vibrant hues of red, green, purple, yellow and orange do more than just make a pretty meal, they contain powerful antioxidant properties that make a profound effect on the total health of consumers.Kola nuts have multiple uses27. The uses of the crop have created an increased demand globally in excess of current production of the crop28. In the rural economy of Ghana, where an estimated 46% of the people of the country live, especially in the forest agro-ecological zones of the country, kola cultivation and marketing plays a key role in the sustenance of livelihoods30. Kola contributes significantly to the foreign revenue of Ghana. The Gross Domestic Product for per capita contribution of kola to the economy of Ghana was US$1,370 and Gross Domestic Product in exchange rates was US$37,543,361,20431. This highlights the economic potential of kola as a cash crop.Ghana kola nut production has increased from 5000 tons in 1961 to 25,303 tons in 20199. In addition, only few plantations/ orchards of the species are available. These observations suggested that the species in its current state is unlikely to meet the continuously growing local and international demands. Exploiting options for large-scale cultivation requires availability of improved planting materials which farmers have indicated as one of their challenges/needs14. Although few cultivars have been selected from open-pollinated seedlings over the years, breeding programs to develop new and improved cultivars were not established until 1967 when active kola research began at the Cocoa Research Institute of Ghana (CRIG) with introduction of some kola genotypes from Oyoko in the Eastern region of Ghana32. Two high yielding hybrids GX1/46 × GX1/16 and JX1/5 × JX1/9 were recently recommended to farmers by the Cocoa Research Institute of Ghana33.Despite the cultural, nutraceutical and economic importance of kola, breeding efforts in kola are limited. Kola production has been based primarily on selections from the wild over a long history. The current exploitation of the species in Ghana mainly relies on just few stands in farmers’ background, home garden and farmsBalanogastris kolae and Sorphorhinus spp), which are among the major constraints of kola value chain35.Management techniques in commercial orchards have been improved remarkably in recent years, but genetic improvement have not kept pace with the large economic value of this important crop. Besides, there is a need of improved varieties to overcome self- and cross-incompatibility, and to resist drought stress and kola weevils Knowledge of compatible and high yielding varieties are critical for the development of high yielding commercial hybrids of kola. Therefore, the availability of information on the compatible partners and patterns of compatibility of lines in the breeding programme among the several valuable kola cultivars collected and conserved at the Cocoa Research Institute of Ghana (CRIG) would boost the national kola production system. A clear definition of the most successful self-compatible and cross-compatible individuals or genotypes would improve fruit set and productivity.48. Furthermore, developing improved varieties with enhanced nut quality attributes ensures consumer acceptability of the end products52. Aside fruit set, it is important to select cultivars with enhanced nut quality attributes such as brix, texture or firmness of nuts, and potential alcohol content. Knowledge on correlation between fruit set and these quality traits in kola is lacking. Correlation strength among traits is important in cultivar development. It provides valuable information that aid breeders in determining the most efficient design for genotype evaluations34.Fruit set assessment is currently the most used method to test self and cross-compatibility among cultivars45. Dominance variance is thus very important in selection for pod set/compatibility in kola. Breeding for expression of dominance is accomplished by the selection of parental pairs that express higher than average for the trait of interest when crossed, that is, heterosis breeding. Utilization of heterosis can speed up the process of generating superior hybrids53. Development of locally preferred hybrids with certain fruit characters along with high yield and adaptation is essentially achieved through heterosis breeding54.Plant breeding is a long process requiring efficient selection of suitable parents with desired traits to produce superior hybrids. Sexual compatibility in kola is determined to a larger extent by non-additive gene effects than by additive genetic effects55. Recent advancements in molecular genetics have confirmed that the cause of heterosis is purely genetic53. Heterosis breeding involves evaluation of elite-parents and first filial generations to detect heterotic hybrids and appropriate parents56 for key traits of crops. Despite the established application of heterosis in plant breeding to identify outstanding genotypes or parents, not much is known about its use in selecting superior parents and hybrids for sexual compatibility and yield in kola.Heterosis or hybrid vigour is a natural phenomenon whereby hybrid offspring of genetically diverse individuals display superior performance relative to the mid-parent value (average heterosis), or to the superior parent (heterobeltiosis) or over check/released cultivar or variety (economic heterosis)C. nitida) genotypes from self, single and double hybrid crosses and heterosis pattern in resulting hybrids for sexual compatibility and key nut yield and quality traits.Therefore, the objective of this study was to assess self-compatible and compatible partners of kola  among the double hybrid crosses for pod set  (Supplementary Table Pod set of the single hybrid crosses (SCC) of JX1 was more than two-fold higher (P < 0.001) than pod set of single hybrid selfs of JX1 germplasm collection Fig. . Pseudo There was significant P < 0.001; df = 27) variation among the single hybrid selfs of GX1 for pod set, which ranged from 1.9% for GX1/25 × GX1/25 to 54.3% for GX1/87 × GX1/87 . The top five self-crosses that expressed significantly higher compatibility were JB1 × JB1, A1 × A1, JB 37 × JB 37, JB 36 × JB 36 and JB 9 × JB 9 . On the other hand, single self-crosses had compatibility scores ranging from 0–4 and compatibility score 2 was predominant   among the Bunso progeny crosses in number of pods, pod weight, number of nuts/pod, weight of unpeeled nuts, weight of peeled nuts and percentage outturn  among the JX1 crosses  were observed among the GX1 self-crosses for yield related traits such as number of pods, pod weight, number of nuts/pod, unpeeled nut weight, and peeled nut weight. Variation among the crosses for outturn was not significant (P > 0.05)   were more associated with dimension 1 which contributed 68.4% of total variation. Also, the SCC-JX1 were more distributed on the positive quadrant of the biplot as compared to SCS-JX1  higher than the overall mean for weight of unpeeled nuts, number of nuts/pod, number of pod, pod weight, pod set and weight of peeled nut weight  higher category mean than overall mean of crosses for brix and pod width (Supplementary Table Highly significant (P < 0.001) and positive correlation was observed between number of pods and pod set, pod weight and pod set, number of nuts per pod and number of pods, number of nuts per pod and pod weight, outturn and pod set, outturn and number of pods, outturn and pod weight, outturn and weight of unpeeled nuts, outturn and weight of peeled nuts  and positive for the relationship between number of pods and pod set, pod weight and pod set, number of nuts per pod and pod set, number of nuts per pod and number of pods, number of nuts per pod and pod weight, nut length and pod width, nut width and nut length, weight of unpeeled nuts and pod set, weight of unpeeled nuts and number of nuts per pod, weight of peeled nuts and pod set, weight of peeled nuts and number of pods, weight of peeled nuts and pod weight, weight of peeled nuts and number of nuts per pod, outturn and pod weight  and strong positive correlation was observed between number of pods and pod set, pod weight and pod set, pod weight and number of pods, number of nuts per pod and pod set, number of nuts per pod and number of pods, number of nuts per pod and pod weight, nut weight and nut length, weight of unpeeled nuts and number of pods, weight of unpeeled nuts and pod weight, weight of unpeeled nuts and number of nuts per pod, weight of peeled nuts and pod set, weight of peeled nuts and number of pods, weight of peeled nuts and number of pods, weight of peeled nuts and pod weight, weight of peeled nuts and number of nuts per pod, outturn and pod weight  and positive correlation was observed between number of pods and pod set, pod weight and pod set, pod weight and number of pods, nut weight and nut length, weight of unpeeled nuts and number of pods, weight of peeled nuts and number of nuts per pod, weight of peeled nuts and number of nuts per pod, weight of peeled nuts and weight of unpeeled nuts, outturn and number of nuts per pod, outturn and weight of unpeeled nuts, outturn and weight of peeled nuts , outturn (%) and brix , GX1  that expressed moderately self-compatible class for self-compatibility could be great sources of genetic materials for developing self-compatible varieties. The selection of these crosses or genetic materials from different germplasm sources would help to capture genetic diversity available for the enhancement of elite lines and make this information accessible for breeding decisions40. Pseudo-pod set is inversely related to pod set and results in low yield in kola. There is a need to consider pseudo pod set as one of the target traits to select against in breeding for sexual compatibility in kola. Crosses such as B1/11 × B1/71 × GX1/46 × GX1/16, Club × JB32 × JX1/5 × JX1/9, JX1/9 × JX1/11 × GX1/46 × GX1/53, JX1/20 × JX1/9, JX1/51 × JX1/20, JX1/5 × JX1/23 and JX1/73 × JX1/23, A1 × A1, JB1 × JB1 which were very highly compatible and expressed no pseudo-pod set would be useful genetic materials to select against pseudo-pod set. Variation in the level of pseudo-compatibility among genotypes in Brassica oleracea has been shown to depend on the genetic background in which the S genes operate69. Johnson70 reported pseudo-compatibility as one of the factors affecting the degree of self-incompatibility in inbred lines of Brussels sprouts.The genetic variability in pseudo-pod set was significant for the JX1 and MX2 crosses. Bunso progeny and GX1 crosses expressed non-significant variation for pseudo pod set. These differences among the crosses of the various germplasm collections could be due to differences in the genetic materials. Pseudo-compatibility is the fertilization by pollen with which they would normally be incompatible; incomplete incompatibility in which gametes which would normally be incompatible form a viable embryo or fruit set72. Nevertheless, some genotypes were cross-incompatible and cannot fertilize each other. In some cases, this was expressed as low pod set. For example, among the single hybrids of JX1, 2% of the crosses made up of JX1/73 × JX1/36 and JX1/87 × JX1/118 were incompatible and 15 of the crosses  exhibited very low compatibility. Selection against these crosses could help make progress in breeding for compatible varieties in kola. Griggs et al.73 and Cuevas and Polito72 reported similar findings in their work on olive.The cross pollinations in general resulted to more pod set than the self-pollinations. Other authors reported that cross pollinations can enhance fertilization as shown by their higher fruit set reports74. However, the double hybrid self-pollinated crosses showed lower degree of compatibility reactions as observed in nearly all self -pollinations. This suggests that the phenomenon of self-incompatibility is expressed even in advanced generations of kola. This could have consequences of reduced yields in advanced generations of kola if recommended varieties are not inter-spaced with pollinizers and are solely established. The issue of self-incompatibility in advanced varieties of kola could be managed through inclusion of pollinizers in orchards to increase yield. In crops exhibiting SI, cultivars that serve as pollen donors (“pollenizers”) are usually interspersed throughout orchards since fruit set depends largely on cross pollinations. Pollenizers are commonly used in canola (Brassica napus L.), sunflower, strawberry (Fragaria x anannasa (Weston), European pear (Pyrus communis), sweet cherry, Japanese plum 77. The use of pollenizers is also recommended in olive (Olea europaea L.)63. Two genotypes A1 and B1 were identified to be great pollinizers of Cola nitida in Ghana34.The fairly good pod set of the double hybrid crosses as compared to the single hybrid crosses in this study could be due to an expression of genetic gains for pod set. The Bunso kola progenies were earlier selected for sexual compatibility or pod set in a hybrid breeding program78. Sporophytic self-incompatibility has been reported in Asteraceae, Betulaceae, Convolvulaceae, sterculiaceae and malvaceae40. Kola is of the family malvaceae.The falling or distribution of double and single crosses into higher compatibility scores than the double and single self-hybrid crosses further confirmed existence of self-incompatibility in kola. Self-incompatibility is a genetically controlled mechanism that prevents self-fertilization in about half of angiosperm species.79, Akpertey et al.80,and Adebola et al.81.The significant variation observed among the kola crosses for pod yield related traits  and nut yield related traits  present an opportunity to select kola hybrids and cultivars that combine high self or cross-compatibility with high yield and good nut attributes. DCC6, DCC9, DCC19, DCC26, DCC32, JX1/1 × JX1/67, JX1/2 × JX1/45, JX1/20 × JX1/118, JX1/21 × JX1/9, JX1/51 × JX1/23, JX1/73 × JX1/23 and JX1/73 × JX1/6 combined high pod and nut yield traits and high nut yield. Selecting these genetic materials would lead to purging of unfavourable alleles whilst retaining or even increasing frequency of favourable alleles for pod set, yield and nut quality. Variation in yield and its related traits in kola was also reported by Onomo et al85. In this study, nuts of kola crosses were assessed for some important quality traits. The results confirmed that there were significant variations among the crosses for total soluble solids or brix for JX1 and MX2 kola gene banks. This suggests genetic diversity among the genotypes for brix and provides an opportunity to select crosses that are high in brix content. Brix was high for JX1/119 × JX1/32, JX1/24 × JX1/45, JX1/25 × JX1/99, JX1/30 × JX1/7, JX1/31 × JX1/23, JX1/51 × JX1/20, JX1/51 × JX1/25, JX1/51 × JX1/36, JX1/51 × JX1/42, JX1/51 × JX1/31, JX1/62 × JX1/6, JX1/63 × JX1/23, and JX1/73 × JX1/23. The top crosses with high brix for MX2 crosses were Club × Club, JB 10 × JB 10, JB 19 × JB 19, JB 26 × JB 26 and P2-1B × P2-1B. Brix is a measure of sugar or sweetness of fruits86. Considering the issue of astringency in kola, crosses that are high in brix could have an improved sensory attributes and good shelf-life during storage. The brix is very important because the higher the brix, the sweeter nut flavour and crop genotypes high in brix are preferred by consumers87. Astringency has been reported by Osei-Bonsu et al.88, Takrama et al.35 and Lowor et al.89 as a poor sensory attribute of kola consumption. Also, kola crosses with high brix content could store better during post-harvest storage. It is generally known that the higher the brix content of fruits, the better the shelf life during storage92.Developing fruit crops with high qualities has been a goal in several breeding programs17. Varieties with higher potential alcohol content are therefore desirable. Potential alcohol does not only influence flavour and sensory perceptions of kola nuts93 but serve as one of the principal characters required in the development and improvement of kola genotypes for domestic and industrial uses. JX1 crosses  and MX2 self-crosses  expressed high potential alcohol content. Though not significant, the following crosses of Bunso progeny  and GX1 crosses  had high potential alcohol content compared to the other crosses. These crosses would be important for developing industrial products like wine.Significant differences were observed among the crosses of JX1 and MX2 gene banks for potential alcohol. However, the variability in this trait for Bunso progeny and GX1 crosses was not statistically different. The difference in the significance of variation of this trait among different populations of kola could be explained by the differences in the genetic composition of genotypes and the environments where the accessions are established. Kola is used to develop various products including soft drinks and wine95. Texture properties are very important in foods for harvesting, processing, packaging, storage and presentation to the consumer/customer. For example, hardness/firmness, one of the texture properties, is one of the most substantial parameters generally used to determine freshness of fruits and vegetables94. All the four populations of kola used in this study did not exhibit significant differences among nuts of crosses for nut firmness except JX1 crosses. The top six crosses of the JX1 with higher nut firmness were JX1/30 × JX1/7, JX1/45 × JX1/45, JX1/62 × JX1/27, JX1/62 × JX1/7, JX1/63 × JX1/113 and JX1/J1 × JX1/33. These materials are great resources to improve nut firmness attribute of kola hybrids.Fruit or nut firmness is an important component of texture and influences sensory perception of consumers. Consumers regard texture as a positive quality attribute donating freshness and storability of products and contributing to the enjoyment of eatingCluster analysis was carried out to group crosses having similar performance in relation to pod set, pseudo-pod set, yield components and nut quality traits. Quantitative analysis regrouped the crosses into 3 clusters for Bunso progeny, JX1 and GX1 gene banks and 5 clusters for the MX2 gene bank which facilitates the selection of diverse crosses or parents for the kola breeding programme. Based on the results, the diversity panel was categorized into three clusters with cluster 2 and 3 containing the best performing crosses for Bunso progeny, JX1 and GX1. Crosses in cluster 2 and 3 for Bunso progeny, JX1 and GX1 and cluster 4 and 5 of MX2 were more distributed at the positive side of the quadrant and were more associated with dimension 1. The dimension 1 contributed 74.1%, 68.4%, 97.1% and 27.4% of the total variability for Bunso progeny, JX1, GX1 and MX2 crosses respectively. Given the information on the contribution of the traits to variation on the PC1 and PC2 axes, the biplots identified the genetic materials with high compatibility, yield and nut quality. The higher category means than overall mean for traits of the crosses that constitute cluster 2 and 3 and 4 and 5 of MX2 indicates that they performed above average of all the crosses. Such crosses would be rewarding if selected and used in kola breeding programmes to develop compatible and high yielding varieties..34 and Adebola et al.81 who found significant and positive correlation between pod set and number of pods, number of nuts /pod, and nut weight. The negative and significant correlations between pod set and pseudo pod set indicates that an increase in pseudo-pod set would result in a decrease in pod set. This necessitates the need to select against pseudo-pod set in kola breeding programmes. Correlation between the nut quality traits and the yield traits was weak and not significant for Bunso progeny crosses. Similarly, correlation between the nut quality traits and the yield traits was weak and not significant for the MX2 crosses except correlation between brix and nut length , brix and nut width , firmness of nuts and nut length . However, in the case of JX1 and GX1 crosses, significantly strong correlations were observed between the nut quality traits and the agronomic/yield traits. For instance, the correlation between brix and pod length and between brix and outturn was 0.81 and 0.84 respectively for JX1 accessions. Similarly, the correlation between brix and outturn and brix and nut width was 0.6 and 0.56 respectively for GX1 accessions. The association of yield traits and nut quality traits for these genetic resources of kola allows the selection of promising genotypes that combines high yield with nut quality traits97. Due to the high demand and the search for new hybrids that meet the requirements of the consumer market, breeding strategies consist of exploring important agronomic traits and improvements in organoleptic properties to favour both higher quality and production. The contrasting results for the kola germplasm sets could be explained by genetic differences of their genotypes and the environments in which they were grown. Brix is affected by a lot of factors including genetics and environmental factors100. Selection and involvement of kola genotypes identified in this study to have appreciable higher contents of brix in breeding programmes could help develop improved varieties with enhanced nut quality.The significant strong correlations of pod set, yield traits such as number of pods, pod weight, number of nuts/pod, weight of unpeeled nuts, weight of peeled nuts and outturn for Bunso progeny, JX1 and GX1 crosses suggested that these economic traits could be improved simultaneously. These results further suggest possible deployment of indirect selection for nut yield using pod set, pod weight, nut width and nut length as surrogate traits in kola breeding programmes. This agrees the findings of Nyadanu et al101 among the parental lines used which is worth testing to inform future decision making in the kola breeding pipeline. This could further be explained by the additive effects of several desired dominant alleles, or as ‘overdominance’ the combined effect of two different alleles at the same gene locus, or a combination of both105. Hence, heterosis helps a breeder to make more stringent selections. The parents of the double hybrid crosses were selected earlier for their high fruit set or compatibility potentials74. Hence linkats containing favourable gene reassortments, especially in linkage disequilibrium, could be preserved. This may account for the very large mid-parent heterosis and heterobeltiosis noted for the double hybrid crosses which was above that of single hybrid crosses. It would be interesting to check if further cross-breeding of the double hybrid crosses could maximize progressive heterosis responses resulting in even higher compatibility in third generation of hybrid crosses.The high prevalence of positive estimates of MPH, BPH and ECH for pod set and outturn among the double hybrid crosses of Bunso progeny suggest that the crosses performed better than their parents and standard varieties for this trait and further indicate absence of bidirectional dominance deviation. The prevalence positive heterosis observed among the single hybrid crosses of JX1 for pod set, outturn and brix indicates that effective progress can be made in the development of compatible and high yield kola varieties with quality nuts. The expression of high and positive heterosis among the double hybrids of Bunso progeny for pod set and outturn and pod set, outturn and brix in the case of JX1 crosses could be dependent on the degree of fit and genetic diversity106 and Alam et al.107 suggested that positive heterosis is desired in the selection for yield and its components, whereas negative heterosis is desired for early cycling and short plant height. In our case however, a positive heterobeltiosis for compatibility, outturn and brix was desirable since it indicates that the crosses were more compatible, had higher nut outturn and brix than their parents.Lamkey and EdwardsSignificant and large variations for sexual compatibility, nut yield and nut quality attributes were observed for crosses of Bunso progeny, JX1, GX1 and MX2 field genebanks of kola in Ghana. The cross pollinations in general resulted to more than two-fold pod set than the self-pollinations confirming the need for pollinizers to increase fruit set in kola. Self-compatible and cross compatible partners within single hybrid and double hybrid crosses were identified. Strong and significant correlation was observed between sexual compatibility and number of pods, pod weight, number of nuts/pod and outturn for the crosses of all the four field gene banks of kola. Significant and positive correlation between yield and nut quality traits observed for JX1 and GX1 crosses provides opportunity to simultaneously develop kola varieties that combine high yield with good nut quality. Very large prevalence of mid-parent heterosis, heterobeltiosis and economic heterosis was observed for the double hybrid crosses of Bunso progeny and single hybrid crosses. Mid-parent heterosis, heterobeltiosis and economic heterosis observed for the double hybrid crosses was above that of single hybrid crosses. This indicates that recurrent selection of compatible kola varieties from advanced generations of kola could be rewarding. The top five crosses with best heterosis for sexual compatibility and an appreciable positive heterosis for outturn and brix were B1/11 × B1/71 × B1/157 × B1/149, B1/11 × B1/71 × B1/296 × B1/177, GX1/46 × GX1/33 × B1/212 × B1/236, JX1/90 × JX1/51 and JX1/51 × JX1/36. The top very highly compatible kola partners identified in this study included B1/11 × B1/71 × GX1/46 × GX1/16, Club x JB 32 × JX1/5 × JX1/9, GX1/46 × GX1/16 × JX1/5 × JX1/9, GX1/46 × GX1/16 × JX1/5 × JX1/9, GX1/46 × GX1/53 × JX1/17 × JX1/5, JX1/9 × JX1/11 × GX1/46 × GX1/53, JX1/21 × JX1/9, JX1/51 × JX1/23, JX1/51xJX1/20, JX1/63 × JX1/23, JX1/73 × JX1/6, and JX1/J1 x JX1/23. The top self-compatible crosses included JX1/17 × JX1/9 × JX1/17 × JX1/9, JX1/23 × JX1/53 × JX1/23 × JX1/53, GX1/46 × GX1/53 × GX1/46 × GX1/53, JX1/9 × GX1/16 × JX1/9 × GX1/16, JX1/9 × JX1/11 × JX1/9 × JX1/11 JX1/31 × JX131, JX1/108 × JX1/108, GX1/27 × GX1/27, GX1/30 × GX1/30, A1 × A1, JB 1 × JB1 and JB37 × JB 37. Involvement of these materials from different germplasm collections in the Ghanaian kola breeding programme could help to capture genetic diversity available in the improvement of the parental population and broaden the genetic base of elite kola germplasm for developing compatible varieties.The source of plant materials used for the study is the Cocoa Research Institute of Ghana (CRIG). The experiment was conducted on four different kola field gene banks held at CRIG namely, MX2, JX1, GX1 and Bunso progeny (advanced germplasm). All the materials were collected under the authority of CRIG in Ghana and all procedures were carried out in accordance with relevant guidelines for handling of plant genetic resources.Assessment of self-compatibility and cross-compatibility of genotypes within the various gene banks was carried out from January 2019 to December 2020. MX2 kola field gene bank is located at CRIG, Tafo. CRIG is located at an altitude of 222 m above sea level with a minimum and maximum temperature of 21 to 37 °C, respectively. The weather conditions during 2019 and 2020 at CRIG are shown in Supplementary Fig. The physical and chemical properties of the soils at MX2 (Tafo); JX1 and GX1 (Afosu), and Bunso progeny trial (Bunso) are presented in Supplementary Table From May 2019 to December 2020, crossing of some genotypes of MX2, JX1, GX1 and Bunso progeny trial was carried out. Partners used in the crossing depends on the availability of male and female flowers for the genotypes involved as flowering in the species is erratic across years. Twenty pollinations/crossings were targeted per each cross. The crossings/pollination was replicated thrice using three pollinators. Before pollination, female flowers about to open were covered or bagged with nylon nets and the male flowers were emasculated before pollen maturation. Freshly opened female flowers were pollinated with pollen grains from newly opened male flowers. Pollen grains from newly opened male flowers were collected with 15 cm thin sticks with sharp ends and smeared to each of the stigmatic lobes of freshly opened female flowers. Pollinated female flowers were re-bagged immediately with nylon nets for further 48 h. For each of the crosses carried out, pod sets, pseudo-pod sets, number of dropped flowers after pollination were recorded two weeks after pollination. Based on the records of pod sets, the crosses were categorized into incompatible, very low compatible, low compatible, moderate compatible, high compatible and very high compatible using a 0–5 scale—0 (no pod set), 1 (1–20% pod set), 2 (21–40% pod set), 3 (41–60% pod set), 4 (61–80% pod set) and 5 (81–100% pod set). The proportion of fruit set to number of flowers pollinated was expressed in percentage and noted as percentage pod set as shown in Eq.  and digital caliper  respectively. The weight of the pods was measured using weighing balance. The pods were broken and the number of nuts per pod was counted and recorded. Nut length and width were measured using digital caliper. Weight of nuts with the peels and weight of the nuts after removing the peels were measured using the weighing balance. The proportion of the total peeled weight of the nut of each cross to the weight of fresh unpeeled nuts was estimated as the outturn as shown in the formula below.Firmness of the nuts from each cross within MX2, JX1, GX1 and Bunso progeny trial was determined using a handheld penetrometer . The nuts collected were stored in a nylon net and kept at room temperature for 24 h to ensure uniform temperature of nuts of the various crosses. A disc of about 2 cm in diameter was peeled of the skin of each nut using a stainless-steel vegetable peeler. A plunger with the tip size 5/16 was used. The plunger was forced into the nut through the peeled surface with the nuts against a stationary hard surface with a uniform speed of about 2 s. Depth of penetration was consistent to the inscribed line on the tip of the plunger. Readings were recorded in poundforce (lbf).0. Potential alcohol content of the juice from the nuts of the various crosses was also measured and recorded.To measure the brix, the refractometer  was calibrated using distilled water. The nuts of the crosses were crushed using mortar and pestle. The juice in the crushed nuts was then sieved through cheeth cloth into glass beaker. A disposable plastic pipette was then used to drop the juices into the window of the refractometer. Total soluble solids (TSS) was determined with a digital refractometer and was expressed in Brix108. To test the effect of the crossing type on pod and pseudo-pod set, a generalised linear model with a binomial distribution error to the data organized as success and failure events was fitted. The prominence of compatibility classes within each specific cross type was compared by using a multiple proportion comparison test from the prop.test  function of base R. An analysis of variance or a Kruskall-wallis test (where relevant) was used to assess the effect of the cross type on the pod and pseudo-pod yield as well as on the nut firmness, brix and potential alcohol content. When the analysis showed significance, mean comparisons were made according to the least significance difference test at P < 0.05 (LSD0.05).To understand the grouping patterns of different type of crosses based on pod and pseudo-pod traits, a hierarchical clustering on principal component analysis was computed using the FactorMineR package109, and the graphical outputs were visualized using the factoextra package110. The correlation strength and significance among different pod and pseudo-pod traits was assessed using function corr_plot  of the Metan package111.Data collected were analysed using the R environment (V. 3.6.2)112. Relative heterosis or mid parent heterosis was estimated as percent deviation of hybrid cross value from its mid-parental self-cross value. The formulae used for estimating the relative heterosis was as follows:Heterosis for sexual compatibility (pod set %), outturn and brix were computed using the overall mean of each cross over replications. The heterosis of single cross hybrids and double cross hybrids were computed after Fehr and (1987)Heterobeltiosis was calculated as the superiority of hybrid cross for pod set, outturn and brix from the better parent self-cross pod set as follows:Two recommended varieties of kola were used for the estimation. Standard variety 1 = GX1/46 × GX1/16 and standard variety 2 = JX1/5 × JX1/9.Supplementary Information 1.Supplementary Information 2.Supplementary Information 3.


The depletion region can be reconstructed by tuning the polarization states generated from the ferroelectric In2Se3 layers. Further, the energy bands at the heterojunction interfaces can be aligned and flexibly engineered using ferroelectric field control. Fast response, self‐driven photodetection, and three‐orders‐of‐magnitude detection improvements are achieved in the switchable visible or near‐infrared operation bands. The results of the study are expected to aid in improving the photodetection performance of vdW optoelectronic devices.Owing to the large built‐in field for efficient charge separation, heterostructures facilitate the simultaneous realization of a low dark current and high photocurrent. The lack of an efficient approach to engineer the depletion region formed across the interfaces of heterojunctions owing to doping differences hinders the realization of high‐performance van der Waals (vdW) photodetectors. This study proposes a ferroelectric‐controlling van der Waals photodetector with vertically stacked two‐dimensional (2D) black phosphorus (BP)/indium selenide (In α‐In2Se3 and black phosphorus (BP) is reported. The energy bands at the heterojunction interfaces can be aligned and flexibly engineered. Fast‐response, self‐driven photodetection, and three‐orders of magnitude detection improvement are achieved in the switchable visible or near‐infrared bands. This work provides a feasible method for the performance improvement of vdWs optoelectronic devices.A ferroelectric‐enabled van der Waals (vdWs) heterojunction through vertically stacking  Pioneering studies on van der Waals heterojunction photodetectors have been reported. Lee et al. reported gate‐tunable photovoltaic (PV) responses with atomically thin heterodiodes based on the stacking structures of n‐MoS2 and p‐WSe2. Ghosh et al. presented a high‐speed WSe2/SnSe2 diode with large negative responsivity through band alignment engineering. Remarkably, Wang et al. demonstrated the first observation of a ballistic avalanche in vertical InSe/BP heterostructures. Moreover, several other vertically stacked heterojunctions, such as BP/MoS2, GaTe/MoS2, and AsP/InSe have been explored. The underlying mechanism relies on the transportation of photogenerated carriers excited in intrinsic channels or depleted p‐n regions. However, the precise control and tuning of doping concentrations remain a common challenge in 2D materials, hindering the photodetection performance of such PV detectors. It is worth noting that electrostatic doping can significantly relieve this problem; however, it is achieved at the cost of a dramatic decrease in photoabsorption and quantum efficiency because it reduces the thickness of the photoactive area to avoid the electrostatic shielding effect.As core components, heterojunction‐based light‐emitting or photodetection devices are crucial to underpinning modern information science and technology. Compared with their bulky counterparts, two‐dimensional (2D) materials provide an outstanding platform for the construction of high‐performance electronic/optoelectronic structures in an ultracompact manner, particularly, for infrared photodetectors. It facilitates the random stacking of different 2D materials to form various functional heterojunctions without lattice mismatch; however, this severely restricts the performance of traditional covalent or ion‐bonded devices.4, 5 2D ferroelectric layers allow high‐quality interfaces, a better combination of nanostructures, and a higher integration density. Indium selenide (In2Se3), a representative ferroelectric III‐VI compound with a monolayer comprising alternating Se or In atoms through covalent bonding, has demonstrated great potential in electronics and optoelectronics. Notably, α‐phase n‐In2Se3 exhibits a stable structure at room temperature, and its out‐of‐plane polarization can be efficiently engineered via the application of an external electric field at different temperatures. Thus, combined with other 2D materials to construct different heterojunctions, 2D ferroelectric materials are expected to yield more flexibleThe advent of 2D ferroelectric materials has ushered a versatile pathway for realizing versatile doping control. Compared with bulky ferroelectric films, which impose high demands on the growth substrates to reduce the lattice mismatch and manufacturing process to avoid defects,16 2D α‐In2Se3 and BP to realize high‐sensitivity photodetection in switchable visible and infrared bands. By tuning the ferroelectric polarization field, the carrier concentration at the interface was controlled to selectively deplete the carrier concentration in the In2Se3 or BP layers. Consequently, the depletion region was broadened and shifted. Moreover, switchable high‐performance detection was achieved in both the visible and infrared wavelengths by flipping the applied direction of the ferroelectric polarization field. The proposed strategy promises a feasible solution for overcoming the tradeoff between light harvesting and wavelength selection in conventional photodetectors.This study proposed a ferroelectric‐enabled van der Waals heterojunction by vertically stacking 22.12Se3 vdW heterojunction is shown in Figure2 substrate, and BP layers were placed above the In2Se3 material. This configuration facilitated better light absorption in the BP and easy implementation of the gate voltage from the substrate. A thin film of the photoresist PMMA was spin‐coated above the device to isolate the air‐induced degradation after preparation. The position of the middle Se atom changes under a perpendicular electric field induced by the gate voltage. This breaks the spatial symmetry and affects the ferroelectric polarization state. An optical micrograph of the device is shown in Figure  No air bubbles existed in the overlapping region of the heterojunction, except for a few impurities on the surface, indicating that the heterojunction had excellent interfacial quality. The line‐scanning profiles of the heterostructures obtained via atomic force microscopy (AFM) are shown in Figure 2Se3 flakes were ≈10 nm. Owing to the absence of in‐plane polarization in 3R α‐In2Se3 for this thickness, the effect of in‐plane polarization was not observed in the following measurement.A schematic of the BP/Inα‐In2Se3 and BP, ultraviolet photoelectron spectroscopy (UPS) measurements were performed, as shown in Figure Ecut) of In2Se3 were measured. The work function (W) of In2Se3 was estimated to be 4.1 eV and the Fermi level was 1.24 eV above the valence band according to formula W = hv – Ecut, where hv = 21.2 eV is the photon energy of the He source. To accurately obtain the bandgap of 3R α‐In2Se3, the photoluminescence spectra of the bulk crystals were also measured from 1.2 to 1.6 eV. With Lorentz fitting, a direct bandgap of ≈1.38 eV was achieved  modes, the A1(LO) and A1(TO) modes were observed owing to symmetry breaking of the atom structure (belonging to the R3m space group). This provides direct evidence that 3R α‐In2Se3 is different from its β phase counterparts, which are stable at room temperature. In a previous study, the presence of the A(LO) mode indicated a lack of antisymmetry in the R3m structure. In particular, the observation of A(LO) mode further confirmed the ferroelectric 3R α‐In2Se3 crystal structure. Compared with the Raman spectra of individual materials, there was no dramatic decrease in the peak intensities and significant translation of the peak positions at the heterojunction. This implies high crystallinity in the overlapping area. Moreover, the disappearance of A(LO) peak of α‐In2Se3 can be attributed to the absorption of BP, which restricts the incident light from reaching the α‐In2Se3 material.To characterize the energy‐band alignment between 3R 2.22Se3 FETs were measured in a dark environment. The linear I–V and Ohmic behaviors at different gate voltages  occurred. In contrast to other ferroelectric dielectrics with only polarization‐bound charges, the ferroelectric semiconductor (3R α‐In2Se3) hosts both mobile and ferroelectric‐bound charges, benefiting from the cooperative behavior of the semiconductor and ferroelectric properties. Further, details can be found in Figure First, the electrical characteristics of BP and Inure 2Se3.32 In 2Se3/BP device, the BP (drain) was grounded to avoid the influence of the applied voltage on the out‐of‐plane polarization in In2Se3. The output current curves for the different ferroelectric polarization states are shown in FigureIDS0.5 V / IDS‐0.5 V) curves in Figure  Thus, to reduce the influence of these uncertainties, the measurement was performed in a vacuum environment at 1.8 × 10−5 mbar. Furthermore, a 180° change in the piezoresponse phase  for p‐doped BP and (Ec − Ef) for n‐doped In2Se3 were determined as 0.028 and 0.14 eV (see Note Ec − Ef) for In2Se3 was consistent with the UPS measurements. Further, the Fermi‐level difference ▵Ef of 0.47 eV was calculated for these two materials before stacking. Because the interfacial state of the heterojunction can be neglected owing to the presence of the dangling bond‐free structure, the distribution of the depletion region was mainly determined by the doping concentrations of the two materials. From the band diagrams, the dark current in the “Up” state at zero bias is lower than in the other states because the narrow bandgap BP is depleted, which substantially reduces the dark current generated by thermal excitation, which is consistent with the test results in Figure 2Se3 vdW heterojunction can be selectively controlled through the effective modulation of carriers at the interface by the ferroelectric field, which promises significant enhancement of the photoresponse.The equilibrium band alignments corresponding to the three different polarization states are shown in Figure 2.32Se3 vdW heterojunction, photoresponse measurements were performed in the visible and near‐infrared bands. FigureIDS–VDS characteristics at different light intensities of 520 nm light irradiation for three ferroelectric polarization states‐ “Fresh,” “Down,” and “Up,” respectively. Figure IDS–VDS curve at different incident powers, resulting in a short‐circuit photocurrent (Iph‐sc) and open‐circuit voltage (Vph‐oc). As shown in Figure Iph‐sc curve exhibited an approximately linear increase with optical power (by power function fitting Iph‐sc ∝ P0.84). However, Vph‐oc exhibited a logarithmic relationship with optical power  as shown in Figure Vph‐oc was logarithmically related to the optical power . Besides, photogating effect features with a nonlinear or exponential relationship between the generated photocurrent and incident optical power. However, the photocurrent and optical power under different ferroelectric polarization states show a linear relationship in our work. The results further confirm that the photoresponse of our device mainly originated from the heterojunction PV effect, photogating effect is not the dominating. The significant improvement in response speed can be attributed to the high mobility of BP and the efficient charge separation enabled by the large built‐in field. The dynamic variation of the photoresponse versus the gate/drain voltage at a fixed optical power at 520 and 1550 nm are shown in Figure R =Iph /P. As evident, the responsivity was enhanced by an order of magnitude at a wavelength of 520 nm and by three orders of magnitude at 1550 nm under a zero‐bias voltage. With reverse bias applied to the external electrode, the peak potential barrier is covered by a steep band structure and the electrons are transported more smoothly. As a result, the photocurrent is also enhanced at a sufficiently large bias. In addition, the selective photoresponse controlled by the ferroelectric polarization state promises dual‐color detection in the visible and near‐infrared regions, thereby providing a viable route for target identification in complex environments.The primary contribution of photogenerated carriers is light absorption in the intrinsically doped or depletion regions. To evaluate the influence of different ferroelectric polarization states on the carrier concentration variation in the depletion region, the photoresponse of the BP/Inα‐phase indium selenide (α‐In2Se3) is modulated by the external electric field. It plays a role of “field transfer” effect in controlling the BP doping concentration. For “Down” state, In2Se3 is in a low doping concentration. Under the ferroelectric field, BP exhibits a heavy p‐type doping. The depletion region mainly exists in In2Se3. The induced ferroelectric field inside In2Se3 has a direction from In2Se3 to the BP material under external bias, which is the same as the built‐in field of the heterojunction. It further enhances the depletion of free carriers in In2Se3 material. The selective photogenerated current at 520 nm incidence mainly occurs in the depleted In2Se3 since its wide bandgap ≈1.39 eV is higher than that of 1550 nm photons. The generated photocarriers can be efficiently extracted by the internal built‐up field within a finite lifetime, whereas, for “Up” state, further widens the depletion width in BP material. The theoretical calculation of depletion region proves the widening of the BP depletion (see Note 2Se3 with ferroelectricity and narrow bandgap BP is proposed to achieve wavelength‐selective photoresponse (520 and 1550 nm) under three states controlled by external bias. Particularly, the depletion region in the BP is gradually widened to enhance the photoresponse at 1550 nm by combining the ferroelectric polarization field. In summary, the heterojunction provides a versatile platform for controlling the depletion region positions through applying different external bias. The presence of tunable ferroelectric polarization field in In2Se3 changes the doping concentration and depletion region distribution at the heterojunction interface, playing an indispensable role in affecting the energy band and thus determining the dark current and photoresponse in different states. The tunable ferroelectric field and the built‐in field both contribute the multifunctional detection properties of our device, including the wavelength‐selective behavior, low dark current, and fast response time.The optoelectronic properties of our devices are a combination of ferroelectric properties and heterojunctions. The ferroelectricity behavior of 32Se3 and narrow‐bandgap p‐type BP materials. Remarkably, an increase of up to three orders of magnitude in the photoresponse was achieved by significantly increasing the distribution of the depletion region in BP under the ferroelectric polarized “Up” state. Further, the ferroelectric vdW heterojunction provided an approach to overcome the low photoresponse owing to the narrow and uncontrollable depletion region in previous 2D heterojunction‐based photodetectors. It is expected that the ferroelectric‐controlled BP/In2Se3 vdW heterojunctions can be employed to engineer high‐sensitivity, multifunctional, and selective fascinating detectors to satisfy various applications in different areas.This study proposed a van der Waals heterojunction with a ferroelectric‐controlled depletion region. The outstanding merits of heterojunctions in switchable response in the visible and near‐infrared, fast response, and large responsivity enhancement were thoroughly demonstrated by assembling the ferroelectric properties of n‐type In42Se3 vdW heterojunction in this study was fabricated using the dry transfer method with polydimethylsiloxane (PDMS) carriers. The 2D In2Se3 and BP flakes were mechanically exfoliated from the bulk material provided by HQ Graphene before being transferred to highly P‐doped silicon substrates  and precisely aligned to overlap with each other to form heterostructures. The transfer was conducted in a N2‐protection glovebox to reduce the oxidation of BP. Further, electron beam lithography  was used to define the electrode pattern. Gold metal and chromium films with thicknesses of 15 and 45 nm, respectively, were deposited via thermal evaporation as contact electrodes, followed by a standard peeling process. Before performing the measurements, a PMMA film was spin‐coated to prevent BP exposure to air and water.The BP/In2Se3 materials.Electronic properties were determined using a commercial Keithley 4200A‐SCS probe station. Response time data were measured using a Tektronix MDO3014 oscilloscope. The Raman spectra were characterized using a Lab Ram HR800 with a 514 nm excitation laser. AFM (Bruker Dimension Icon) was used to determine the thickness of the 2D materials. A UPS (PHI5000 VersaProbe III [Scanning ESCA Microprobe) Spherical Analyzer (SCA)] was used to acquire the band structures  of the InThe authors declare no conflict of interest.Supporting InformationClick here for additional data file.


Predictions are compared with data from an experimental Ni-based superalloy as well as commercial superalloys for which published data are available. The methodology was generally successful in predicting the transition temperature of the commercial superalloys but underpredicted the transition temperature of the experimental superalloy by approximately 50–100 °C. The difference in the transition temperature of the experimental superalloy to form a continuous Al2O3 scale is primarily attributed to a complex oxide subscale that increased the internal volume fraction of oxide and led to reduced oxygen ingress. The sensitivity and limitations of the methodology are discussed, and recommendations are made to refine the methodology to facilitate the interpretation of oxidation behaviour in polycrystalline Ni-based superalloys.An assessment is made of the Wagner transition criteria for predicting the formation of a continuous AlThe online version contains supplementary material available at 10.1007/s11085-023-10163-5. This is typically achieved by selecting alloy compositions that automatically form a passive oxide layer on the surface that hinders further oxidation damage. Al and Cr are well known for producing protective oxides and are particularly suitable for selective oxidation –4. Giggi2O3 scales (Type II) for oxidation resistance because they experience relatively lower service temperatures than their single-crystal turbine blade counterparts. At lower temperatures, Cr2O3 forms a continuous scale faster than Al2O3 and provides superior corrosion resistance. However, Cr2O3 is unsuitable at higher temperatures as it can form volatile compounds (e.g. CrO3). This results in significant mass loss at temperatures beyond 1000 °C, and at lower temperatures when the gas velocity is sufficiently high. Critically, this instability of Cr2O3 at higher temperatures, combined with relatively slower elemental diffusion in Al2O3  from Giggins and Pettit (GP)  was calculated with Eq.  to 4.8 × 10−4 (1100 °C) in Ni–Al alloys. Nesbitt \documentd Grundy  reportedorted in , whereasorted in  calculatorted in  and 41]\documentorted in . Consideorted in –45 and morted in . Howeverorted in  calculatorted in  and argu2O3 scale is established. Using the dissociation pressure of Cr2O3 would result in a smaller oxygen partial pressure and 2O3 scale begins to form that the expressions become less compatible. While calculating the dissociation pressure of Cr2O3 from standard Gibbs free energies is relatively straightforward, it would be more challenging to implement alongside the work of Park and Altstetter  for susormation , which i2O3 and possible synergistic effects. However, Eq.  that surpasses the minimum values (8.84 at% and 6.98 at%) predicted by the Wagner criterion. The limitation of the Wagner criterion to accurately determine the Type III oxidation transition temperature could be attributed to its failure to account for compound oxide scale effects.The increased oxide volume fraction of the complex oxide subscale at 900–950 °C Fig. , combined alloys , 54 and d alloys , suggest−4, −10 cm2/s, and −13 cm2/s gave a value of Thermo-Calc (1.88 × 10−12 cm2/s) in Table The sensitivity of the Wagner criterion to its input parameters was examined by using different values , 48, 56 2O3 scale. Notably, its −12) as the commercial Al2O3 formers and an order of magnitude higher than the commercial Cr2O3 formers (× 10−13). Its −5 mg2/cm4 h) is also an order of magnitude lower than the commercial Cr2O3 formers despite relying on the formation of Cr2O3 for oxidation resistance. This is supported by the TGA results for Alloy X in Fig. 2O3 formers can be attributed to its higher Al concentration (11.30 at%), which could facilitate rapid diffusion to the metal–oxide interface. In addition, Alloy X is the only investigated alloy that contains an appreciable concentration of Mn, which has been previously reported to improve oxidation resistance [The Al concentration of Alloy X exceeds the calculated sistance , 58. Thesistance . Howevermentclass2pt{minim2O3 formation at 800 °C. However, Alloy X has an adequate Al concentration to satisfy the calculated 2O3 scale if established under different conditions. For instance, a suitable pre-oxidation treatment at higher temperatures could lower the 2O3 formation at lower service temperatures.The mixed results for 1 Tables  and 4 su2O3 scale regeneration and the potential formation of less-protective oxides could lead to break-away oxidation. In this regard, 2O3 scale after spallation. However, partial or complete spallation of the scale contradicts the assumption of an initially present continuous external scale for 2O3 scales are formed on the alloy surface. For complete spallation, the entire alloy surface is exposed, necessitating re-compliance of the 2O3 scales formed during isothermal oxidation if it is to be considered for commercial applications.It is acknowledged that oxide spallation in cyclic conditions is a concern for in-service operation. The uncertainty of Al2O3 scales, may possess a composition inclined to undergo Type III oxidation, wherein the influence of surface roughness on oxidation mechanisms could be significant. Further research is therefore warranted to explore the impact of surface roughness on the oxidation behaviour of Alloy X, to assess its commercial suitability.The samples in this study were polished to a 1-µm diamond surface finish which is not representative of commercial turbine disc components. Since Wagner’s criteria assume ionic diffusion in the oxide scale is rate-controlling and reactions at the metal–surface and oxide–gas boundaries are in equilibrium, it is inferred that the surface morphology is ignored. Therefore, the polished samples allowed for a comparison with Wagner’s criteria and the literature as well as providing a uniform initial surface condition for reproducibility. However, it should be acknowledged that Alloy X, which showed regions of continuous Al2O3 scale were used to predict the critical concentration of Al required for continuous Al2O3 formation in experimental and commercial Ni-based superalloys from 750 to 1050 °C:2O3-forming commercial superalloys and simpler Ni–Cr–Al systems outlined in [The Wagner model successfully predicted the oxidation behaviour of known Allined in .Testing the Wagner model on the experimental Alloy X at multiple temperatures gave an underprediction of the transition temperature by approximately 50–100 °C.The calculation of the internal oxide volume fraction Below is the link to the electronic supplementary material.


The anomalous phase shift is larger for shorterdistances between the JJs and vanishes for distances much longer thanthe superconducting coherence length. Results are consistent withthe hybridization of Andreev bound states, leading to the formationof an Andreev molecule. Our devices constitute a realization of atunable superconducting phase source and could enable new couplingschemes for hybrid quantum devices.We perform switchingcurrent measurements of planar Josephson junctions(JJs) coupled by a common superconducting electrode with independentcontrol over the two superconducting phase differences. We observean anomalous phase shift in the current–phase relation of aJJ as a function of gate voltage or phase difference in the secondJJ. This demonstrates the nonlocal Josephson effect, and the implementationof a φ A prominent example is the electrostatic tuning of the criticalcurrent,12 which allowsfor JJ field-effect transistors,16 voltage-tunable superconductingqubits,20 resonators,22 and amplifiers.25 Moreover, the interplay between ABSs, spin–orbit interaction,and Zeeman fields results in nonreciprocal switching currents29 and anomalous phase offsets, or φ0-junctions,38 with applications in superconducting electronics and spintronics.39 A yet largely unexplored possibility offeredby superconductor–semiconductor hybrids is the engineeringof Andreev molecules from the hybridization of spatially overlappingABSs.43 Predicted to arise in JJs coupling over length scales comparableto the superconducting coherence length, Andreev molecules offer apromising platform to realize φ0-junctions40 and novel manipulation and coupling schemesfor Andreev qubits.41 Experimental studiesof ABS hybridization focused on two-terminal quantum dots45 and quantum dot chains.46 Recently, engineeringof Andreev molecules was demonstrated in open, multiply connectedgeometries47 and laterally coupled JJs.49 Measurements of the switching current in double InAs nanowires revealeda nonlocal Josephson effect,48 howeverthe device geometry did not allow measurements of phase shifts inthe current–phase relation (CPR).The developmentof high-qualityhybrid superconductor–semiconductor materials over the pastdecade enabled new possibilities in superconducting electronics andquantum computing.42 to the interplay between two distinct Cooper pair transfer mechanismsat φ1 = φ2 and at φ1 = −φ2, namely double crossed Andreev reflection(dCAR) and double elastic cotunneling (dEC), respectively. Differentfrom the proposal of ref . Such a coupled system realizes the nonlocal Josephson effect:an anomalous phase shift  was nonlocally induced in JJ1 by the phasedifference across JJ2. Varying the length L of thecommon superconducting electrode, we observed that the phase shiftwas larger for small L, and it vanished for L much longer than the superconducting coherence length.Our observations are consistent with the hybridization of ABSs originatingfrom the two JJs, resulting in the formation of an Andreev molecule.As the superconducting phase offset is electrically tuned by a currentflowing in a flux line or a voltage applied to a gate, our devicesconstitute a demonstration of a tunable superconducting phase source.Our findings open up new avenues for the design and implementationof advanced nanoscale quantum devices with enhanced controllabilityand functionality.The double-loop geometry allowed usto independently tune the superconductingphase differences φ50 measured in a dilution refrigerator with a base temperature below10 mK. R,embedded in the arm of a large superconducting loop, threaded by flux ΦL. The region where the two loops merged (bottomright in L. We labelthe bottom and top junctions in Supporting Information for details).Both JJ1 and JJ2 were controlled by gate electrodes, energized byvoltages of V1 and V2, respectively. A third gate, at voltage V3, was set to −3 V throughout the experiment toprevent parallel conducting paths. A narrow Al constriction was definedon the left arm of the large Al loop  definedin the same epitaxial heterostructure of InAs and Al, Al loop 1a. This IL and IR in the flux lines. Switching currents of theentire device were obtained by ramping the current I from zero to around 35 μA (depending on the device) with arepetition rate of 133 Hz and detecting when the four-terminal voltagedrop V exceeded a threshold. As planar devices arecharacterized by an intrinsically large spread of their switchingcurrent,51 we averaged the results over16 ramps for each data point. In all of our devices, JJ1 had a maximumsupercurrent of approximately 450 nA, while the Al constrictions consistentlyshowed switching currents of IAl ∼34 μA, independent of ΦL and ΦR. Due to the large asymmetry between the arms of the device, theswitching current ISW of the right armwas obtained by subtracting IAl from theswitching current of the entire device. Further details on the measurementsetup are discussed in the Supporting Information.The measurement setup used to measure the switching currents isschematically depicted in 1 across JJ1 was tuned by the magnetic flux impinging within the perimeterof the device as φ1 = 2π(ΦL + ΦR)/Φ0, where Φ0 is the superconducting magnetic flux quantum. The phase differenceφ2 across JJ2 was instead tuned by the magnetic fluxΦR. However, as JJ2 was bypassed by a large stripeof Al, φ2 was not expected to affect ISW, unless a nonlocal Josephson effect was present; inthe absence of coupling between JJ1 and JJ2, ISW would simply represent the CPR of JJ1.Our devices allowed an independent tuning of the phase differencesacross the two junctions. The phase difference φWe furthernote that the finite geometric and kinetic inductancesof the superconducting loops were too small to significantly distortthe CPR of JJ1 and JJ2. Similarly, coupling between the two loopsmediated by shared inductance was negligible. The inductances ofthe inner and outer loops were 105 pH and 200 pH, respectively, whiletheir common Al segment (right side of ISW of Device 1as a function of IL and IR performed with V1 = 0 and V2 = 0 (both JJs open). Clear supercurrent oscillationswere present, which depended on both IL and IR. The vector ΦL + ΦR in 1 is expected to be maximally modulated. The vectors ΦR – ΦL and ΦL indicate thedirections over which φ1 and φ2 areconstant, respectively. Details of the definition of such vectorsare presented in the Supporting Information. Clear modulations of the supercurrent were observed along ΦR – ΦL, confirming a coupling betweenJJ1 and JJ2. V2 = −1.2 V and V2 = −2.4 V, respectively. As V2 was set more negative, JJ2 was depleted, andthe supercurrent oscillations became more and more regular, untilsupercurrent modulations were completely suppressed along ΦR – ΦL . 2 and γ1, respectively, measured for V1 = 0. Selected linecuts of V2, saturating to a conventional forward-skewedCPR for V2 ≲ −2 V.ISW as a function of φ1 for selected valuesof φ2 (see Supporting Information for details). For example, ISW(φ1) for φ2 = 0.8π, that is, when thephase shift was found to be the largest. I1 and Δφ1, which representthe anomalous supercurrent  and anomalous phase shift, respectively. The dependenceof ΔI1 and Δφ1 on φ2 is further shown in 40 Time-reversal symmetry requires I1 = −I1, which imposesΔφ1 = 0 at φ2 = .This condition was used to accurately account for a constant offsetto Δφ1. For φ2 ≠ , the CPR of JJ1 gained an anomalous phase shift Δφ1 or, equivalently, an anomalous supercurrent ΔI1 at φ1 = 0, controlled byboth phase and gate tuning of JJ2. Both the anomalous phase shiftand anomalous supercurrent were symmetric and periodic in φ2, consistent with theoretical expectations.40 The phase shift Δφ1 was also anodd function of φ2, compatible with the relativeinterplay of the dCAR and dEC processes as a function of the nonlocalphase. There was also a pronounced forward skewness toward Δφ1, which is a consequence of the nonsinusoidal CPR of bothJJs. The largest Δφ1 measured in Device 1 was±0.22π, which resulted in ΔI1 = ± 170 nA. These values might be increased furtherin devices with shorter L. We confirmed that couplingtakes place over length scales of at least 400 nm but significantlysmaller than 4 μm. Such length scales are consistent with thoseof superconducting correlations in our devices. In the InAs quantumwell, we expect a superconducting coherence length ξInAs ∼ 600 nm, compared to ξAl ∼ 100 nmof the Al film52 . These length scales are compatible with the absence of couplingin Device 3 (L = 4 μm), and they indicate thatboth the semiconductor and the superconductor might be relevant tomediating the coupling over short JJ separations. Extending our experimentsto several devices with varying L values will makeit possible to extract the typical length scale governing the nonlocaleffect, thus providing a better understanding of the microscopic couplingmechanisms.V1 affected the amplitude of ISW but not Δφ1, while V2 tuned Δφ1 without any influence onthe amplitude of ISW. A gate-dependentphase shift can result from tuning of the transmission and numberof ABSs in each JJ, affecting the degree of hybridization betweenABSs in JJ1 and JJ2. If the gate tuning of Δφ1 was only due to a change of the ABS transmissions as a functionof V2, we would expect the effect to besymmetric with respect to JJ1 and JJ2, contrary to the observations.Previous work also showed that gate voltages mainly affect hybridJJs by reducing the number of ABSs, not by changing the ABS transmission.53 We instead speculate that the different dependencesof ISW on V1 and V2 reflect how Δφ1 is affected by the number of ABSs present in each junction.In the present case, V2 controls Δφ1 by tuning the number of ABSs in JJ2 available for hybridizationwith the ABSs in JJ1. As JJ2 is depleted, ABSs in JJ1 progressivelylose states of JJ2 to hybridize with, until a conventional CPR isrestored. On the other hand, setting V1 negative decreases the number of ABSs in JJ1, which directly resultsin a decrease of ISW. However, as longas the number of ABSs in JJ2 is unchanged, the hybridization of theremaining ABSs in JJ1 is also unchanged, and Δφ1 remains constant.Further insights into the nonlocal Josephson effectare gainedvia the gate dependence shown in 0-junction behaviorin the same material system by the combination of spin–orbitcoupling and external magnetic fields.37 To achieve similar Δφ1 as in 0-junctionbehavior induced by ferromagnetic elements in a JJ and field cycling,constituting a phase battery;38 the φ0-junction that we realized here is instead continuously andelectrically tunable over short time scales; hence, it could be promptlyutilized as a phase source for applications in superconducting electronicsand spintronics.Previous work demonstrated φIn conclusion, our investigation of phase-tunableJJs placed inclose proximity to each other and sharing a common electrode demonstratedthe formation of an Andreev molecule exhibiting a nonlocal Josephsoneffect. This manifested as an anomalous phase shift and an anomaloussupercurrent arising in one JJ, depending on phase tuning and gatingof the second JJ. In light of our results, Andreev molecules expandthe available toolset of functionality in hybrid materials, also enablingnew quantum manipulation schemes and coupling architectures for hybridqubits.