Organoid Modeling of the Tumor Immune Microenvironment.

In vitro cancer cultures, including three-dimensional organoids, typically contain exclusively neoplastic epithelium but require artificial reconstitution to recapitulate the tumor microenvironment (TME). The co-culture of primary tumor epithelia with endogenous, syngeneic tumor-infiltrating lymphocytes (TILs) as a cohesive unit has been particularly elusive. Here, an air-liquid interface (ALI) method propagated patient-derived organoids (PDOs) from >100 human biopsies or mouse tumors in syngeneic immunocompetent hosts as tumor epithelia with native embedded immune cells (T, B, NK, macrophages). Robust droplet-based, single-cell simultaneous determination of gene expression and immune repertoire indicated that PDO TILs accurately preserved the original tumor T cell receptor (TCR) spectrum. Crucially, human and murine PDOs successfully modeled immune checkpoint blockade (ICB) with anti-PD-1- and/or anti-PD-L1 expanding and activating tumor antigen-specific TILs and eliciting tumor cytotoxicity. Organoid-based propagation of primary tumor epithelium en bloc with endogenous immune stroma should enable immuno-oncology investigations within the TME and facilitate personalized immunotherapy testing.

Descending thoracic aortic mural ulceration is associated with postoperative spinal cord ischemia after branched endovascular aortic aneurysm repair.

OBJECTIVE: Paraplegia is one of the most feared complications after thoracoabdominal aortic aneurysm repair. The purpose of this study is to determine whether aortic thrombus characteristics are associated with spinal cord ischemia (SCI) after branched endovascular aneurysm repair (BEVAR). METHODS: From April 2011 to April 2020, 62 patients underwent elective BEVAR for thoracoabdominal aortic aneurysm and pararenal aortic aneurysms using a low-profile device and had a complete preoperative computed tomography angiography of the aorta from the sinotubular junction to the aortic bifurcation. Aortic thrombus was evaluated for thrombus thickness ≥5 mm, thrombus >2/3 of aortic circumference, and the presence of an ulcer-like thrombus. One point was assigned at each 5 mm axial image if all 3 criteria were met, resulting in a total "shaggy score" for the entire aorta. Data on demographics, procedural details, and outcomes were collected prospectively. All patients underwent a standard spinal cord protection protocol, including routine cerebrospinal fluid drainage. In July 2016, an insulin infusion protocol (IIP) was initiated to maintain postoperative blood glucose levels <120 mg/dL for 48 hours. The primary clinical end point was postoperative SCI. RESULTS: 10 (16%) patients developed postoperative SCI: 6 with transient paraparesis, 2 with persistent paraparesis, and 2 with persistent paraplegia. Patients with SCI were older, had higher shaggy scores, and were less likely to have been on an IIP. There were no significant differences in demographics, aneurysm type, or operative parameters. In a logistic multivariate regression model for SCI, age (odds ratio [OR]: 1.2 [1.1-1.4], P = .02) and shaggy score (OR: 1.2 [1.1-1.4], P = .02) were independently associated with increased risk of SCI, whereas treatment with the IIP was associated with lower risk of SCI (OR: 0.04 [0.006-0.50], P = .05). Of the individual components of the shaggy score, higher descending thoracic aortic ulcer scores were the most strongly associated with postoperative SCI (P = .009). CONCLUSIONS: Preoperative characterization of aortic wall thrombus is an important adjunctive tool for individualized clinical decision-making and patient counseling about the risk of SCI after BEVAR.

Relevance of BEST-CLI trial endpoints in a tertiary care limb preservation program.

OBJECTIVE: Major adverse limb event-free survival (MALE-FS) differed significantly by initial revascularization approach in the BEST-CLI randomized trial. The BEST-CLI trial represented a highly selected subgroup of patients seen in clinical practice; thus, we examined the endpoint of MALE-FS in an all-comers tertiary care practice setting. METHODS: This is a single-center retrospective study of consecutive, unique patients who underwent technically successful infrainguinal revascularization for chronic limb-threatening ischemia (2011-2021). MALE was major amputation (transtibial or above) or major reintervention (new bypass, open bypass revision, thrombectomy, or thrombolysis). RESULTS: Among 469 subjects, the mean age was 70 years, and 34% were female. Characteristics included diabetes (68%), end-stage renal disease (ESRD) (16%), Wound, Ischemia, and foot Infection (WIfI) stage 4 (44%), Global Limb Anatomic Staging System (GLASS) stage 3 (62%), and high pedal artery calcium score (pMAC) (22%). Index revascularization was autogenous vein bypass (AVB) (30%), non-autogenous bypass (NAB) (13%), or endovascular (ENDO) (57%). The composite endpoint of MALE or death occurred in 237 patients (51%) at a median time of 189 days from index revascularization. In an adjusted Cox model, factors independently associated with MALE or death included younger age, ESRD, WIfI stage 4, higher GLASS stage, and moderate-severe pMAC, whereas AVB was associated with improved MALE-FS. Freedom from MALE-FS, MALE, and major amputation at 30 days were 90%, 92%, and 95%; and at 1 year were 63%, 70%, and 83%, respectively. MALE occurred in 144 patients (31%) and was associated with ESRD, WIfI stage, GLASS stage, pMAC score, and index revascularization approach. AVB had superior durability, with adjusted 2-year freedom from MALE of 72%, compared with 66% for ENDO and 51% for NAB. Within the AVB group, spliced vein conduit had higher MALE compared with single-segment vein (hazard ratio, 1.8; 95% confidence interval, 0.9-3.7; P = .008 after inverse propensity weighting), but there was no statistically significant difference in major amputation. Of the 144 patients with any MALE, the first MALE was major reintervention in 47% and major amputation in 53%. Major amputation as first MALE was associated with non-AVB index approach. Indications for major reintervention were symptomatic stenosis/occlusion (54%), lack of clinical improvement (28%), asymptomatic graft stenosis (16%), and iatrogenic events (3%). Conversion to bypass occurred after 6% of ENDO cases, two-thirds of which involved distal bypass targets at the ankle or foot. CONCLUSIONS: In this consecutive, all-comers cohort, disease complexity was associated with procedural selection and MALE-FS. AVB independently provided the greatest MALE-FS and freedom from MALE and major amputation. Compared with the BEST-CLI randomized trial, MALE after ENDO in this series was more frequently major amputation, with relatively few conversions to open bypass.

Perceived discrimination and psychological distress among Mainland Chinese immigrant women in Hong Kong: The indirect effects of tolerance of uncertainty and common dyadic coping.

OBJECTIVES: By studying Mainland Chinese immigrant women who married Hong Kong men, this study examined the association between their perceived discrimination and psychological distress after the 2019-2020 social movement in Hong Kong. Additionally, this study examined the indirect effects of individual coping strategies (tolerance of uncertainty) and couples' coping strategies (common dyadic coping), guided by the cultural and developmental psychopathology framework. METHOD: Ninety-nine Mainland Chinese immigrant women who married Hong Kong men participated in this cross-sectional survey. RESULTS: We found a positive association between perceived discrimination and psychological distress (r = .50, p < .01). Reduced uncertainty tolerance and low levels of common dyadic coping both showed indirect effects on the discrimination-psychological distress association. Tolerance of uncertainty had a larger indirect effect than common dyadic coping. CONCLUSIONS: Focusing on the psychological adjustment of immigrant women facing discrimination, our findings underscore the importance of preserving individual- and couple-level resources. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Iliac artery calcification score stratifies mortality risk estimation in patients with chronic limb-threatening ischemia undergoing revascularization.

OBJECTIVE: Patients with chronic limb-threatening ischemia (CLTI) are at high risk for adverse limb outcomes and mortality. Using the Vascular Quality Initiative (VQI) prediction model to estimate mortality after revascularization can assist with clinical decision-making. We aimed to improve the discrimination of the 2-year VQI risk calculator by incorporating a common iliac artery (CIA) calcification score based on computed tomography scans. METHODS: This was a retrospective analysis of patients who underwent infrainguinal revascularization for CLTI from January 2011 to June 2020 and had a computed tomography scan of the abdomen/pelvis 2 years before or up to 6 months after revascularization. CIA calcium morphology, circumference, and length were scored. Bilateral scores were summed for the total calcium burden (CB) score, which was trichotomized (mild, 0-15; moderate, 16-19; severe, 20-22). The VQI CLTI model was used to categorize patients as low, medium, or high risk for mortality. RESULTS: A total of 131 patients with a mean age of 69±12 years were included in the study, and 86 (66%) were men. CB scores were mild in 52 (40%), moderate in 26 (20%), and severe in 53 (40%) patients. Older patients (P = .0002) and those with coronary artery disease (P = .06) had higher CB scores. Patients with severe CB scores were more likely to undergo infrainguinal bypass compared with those with mild or moderate CB scores (P = .006). The 2-year VQI mortality risk was calculated to be low in 102 (78%), medium in 23 (18%), and high in 6 (4.6%) patients. In the "low-risk" VQI mortality subgroup, 46 (45%) patients had mild, 18 (18%) had moderate, and 38 (37%) had severe CB scores, and patients with severe CB scores had significantly higher risk of mortality compared with those with mild or moderate scores (hazard ratio, 2.5; 95% confidence interval, 1.2-5.1; P = .01). In this "low-risk" VQI mortality subgroup, CB score further stratified the risk of mortality (P = .04). CONCLUSIONS: Higher total CIA calcification was significantly associated with mortality in patients undergoing infrainguinal revascularization for CLTI, and preoperative assessment of CIA calcification may help with perioperative risk stratification and guide clinical decision making in this population.

Presenting limb severity is associated with long-term outcomes after infrainguinal revascularization for chronic limb-threatening ischemia.

OBJECTIVE: The SVS Wound, Ischemia, foot Infection (WIfI) limb staging system was established to estimate risk of major amputation in chronic limb-threatening ischemia (CLTI) and better stratify outcomes comparisons. There is little data on treatment outcomes beyond 1 year based on presenting WIfI stage. METHODS: This is a single-institution retrospective study of 413 patients who underwent infrainguinal revascularization for CLTI (2011-2021) with data available for WIfI staging. Patient characteristics and outcomes were gathered from the electronic medical record. Data were analyzed based on presenting WIfI stage and initial treatment received at our center. RESULTS: Presenting WIfI stages were 1 to 2 (23%), 3 (27%), and 4 (50%). Index revascularization approach was endoluminal (59%), autogenous vein bypass (29%), or non-autogenous bypass (13%). Operative mortality within 30 days was 2.9% and was not associated with WIfI stage or revascularization approach. Median limb follow-up time was 502 days (interquartile range [IQR], 112-1256 days), and median survival follow-up time was 932 days (IQR, 343-1770 days). Major amputation or death occurred in 19% and 46% of patients at median times of 119 days (IQR, 28-314 days) and 739 days (IQR, 204-1475 days), respectively. WIfI stage was independently associated with major amputation (P = .001), as was initial revascularization approach (P = .01). In a Cox proportional hazards model, factors independently associated with major amputation were male sex (hazard ratio [HR], 1.4; 95% confidence interval [CI], 1.04-2.0; P = .03), diabetes (HR, 1.8; 95% CI, 1.3-2.5; P = .001), WIfI stage 4 (HR, 2.3; 95% CI, 1.5-3.5; P < .001), and non-autogenous bypass (HR, 2.9; 95% CI, 2.1-4.2; P < .001). In a Cox proportional hazards model for mortality, independently associated factors were age (HR, 1.04; 95% CI, 1.02-1.05; P < .001), end-stage renal disease (HR, 2.8; 95% CI, 1.9-4.0; P < .001), congestive heart failure (HR, 1.9; 95% CI, 1.4-2.5; P < .001), chronic obstructive pulmonary disease (HR, 1.5; 95% CI, 1.1-2.1; P = .02), and WIfI stage 4 (HR, 1.6; 95% CI, 1.04-2.2; P = .03). Among those presenting with WIfI stage 4 limbs, Kaplan-Meier estimated rates of freedom from major amputation or death at 2 years were 71% ± 3.7% and 68% ± 3.5%, respectively. In an inverse propensity weighted Cox proportional hazards model, non-white race (HR, 1.5; 95% CI, 1.01-2.2; P = .047), diabetes (HR, 2.0; 95% CI, 1.2-3.3; P = .008), Global Anatomic Staging System infrapopliteal grade (HR, 1.2; 95% CI, 1.05-1.3; P = .005), non-autogenous bypass (HR, 3.2; 95% CI, 1.9-5.3; P < .001), and endoluminal revascularization (HR, 2.6; 95% CI, 1.6-4.3; P < .001) were independently associated with major amputation in the WIfI stage 4 subgroup. CONCLUSIONS: Presenting WIfI stage is strongly associated with long-term risks of major amputation and death following infrainguinal revascularization for CLTI and should be used to stratify outcomes comparisons. Effective revascularization is critical in WIfI stage 4 disease, and autogenous vein bypass provides durable long-term limb preservation.

Pedal arterial calcification score is associated with the risk of major amputation in chronic limb-threatening ischemia.

OBJECTIVE: The medial arterial calcification (MAC) score is a simple metric that describes the burden of inframalleolar calcification using a plain foot radiograph. We hypothesized that a higher MAC score would be independently associated with the risk of major amputation in patients with chronic limb-threatening ischemia (CLTI). METHODS: We performed a single-institution, retrospective study of 250 patients who had undergone infrainguinal revascularization for CLTI from January 2011 to July 2019 and had foot radiographs available for MAC score calculation. A single blinded reviewer assigned MAC scores of 0 to 5 using two-view minimum plain foot radiographs, with 1 point each for calcification of >2 cm in the dorsalis pedis, plantar, and metatarsal arteries and >1 cm in the hallux and non-hallux digital arteries. RESULTS: The MAC score was 0 in 36%, 1 in 5.2%, 2 in 8.4%, 3 in 14%, 4 in 14%, and 5 in 21%. The MAC score was trichotomized to facilitate analysis and clinical utility (mild, MAC score 0-1; moderate, MAC score 2-4; and severe, MAC score 5). The variables independently associated with a higher MAC score were male sex, diabetes, end-stage renal disease, and the global limb anatomic staging system pedal score. The MAC score was not associated with the Society for Vascular Surgery WIfI (wound, ischemia, foot infection) grade or overall WIfI stage (P = .58). The median follow-up was 759 days (interquartile range, 264-1541 days). A higher MAC score was significantly associated with the risk of major amputation (P < .0001). In a Cox proportional hazards multiple regression model for major amputation that included the trichotomized MAC score, diabetes, end-stage renal disease, and WIfI stage (1-3 vs 4). The MAC score (MAC score 5: hazard ratio [HR], 4.9; 95% confidence interval [CI], 1.9-13.1; P = .001; MAC score 2-4: HR, 3.4; 95% CI, 1.3-8.8; P = .01) and WIfI stage (WIfI stage 4: HR, 2.1; 95% CI, 1.1-3.9; P = .03) were significantly associated with the risk of major amputation. In the subsets of patients with the most advanced WIfI stage of 3 to 4 (191 of 250; 76%) and patients with diabetes (185 of 250; 74%), the MAC score further stratified the risk of major amputation on univariate and multivariate analyses. CONCLUSIONS: The MAC score is a simple, practical tool and a strong independent predictor of major amputation in patients with CLTI. It provides novel clinical data that are currently unmeasured using any validated CLTI staging system. The MAC score is a promising standardized measure of inframalleolar disease burden that can be used in conjunction with the WIfI staging system to help improve outcomes stratification and determine the optimal treatment strategies for patients with CLTI.

Capturing the complexity of open abdominal aortic surgery in the endovascular era.

OBJECTIVE: Volume and quality benchmarks for open abdominal aortic surgery and particularly open aortic aneurysm repair (OAR) in the endovascular era are guided by the Society for Vascular Surgery guidelines, but the Vascular Quality Initiative (VQI) OAR module fails to capture the full spectrum of complex OAR. We hypothesized that VQI-ineligible complex OAR would be the dominant form of open repairs performed at a VQI-participating tertiary center. METHODS: All OAR cases performed at a single tertiary care center from 2007 to 2020 were reviewed. The VQI OAR criteria were applied with exclusions (non-VQI) defined as concomitant renal bypass, clamping above the superior mesenteric artery or celiac artery, repairs performed for trauma, anastomotic aneurysm, isolated iliac aneurysm, or infected aneurysms. Linear regression was used to assess temporal trends. RESULTS: Among a total of 481 open abdominal aortic operations, 355 (74%) were OAR. The average annual OAR volume remained stable over 14 years (25 ± 6; P = .46). Non-VQI OAR comprised 54% of all cases and persisted over time (R2 = 0.047, P = .46). Supraceliac clamping (35%) was often necessary. The proportion of endograft explantation cases significantly increased over time from 4% in 2007 to 20% in 2019 (P = .01). Infectious indications represented 20% (n = 70) of cases. Visceral branch grafts were performed in 16% of all cases. OAR for ruptured aneurysm constituted 10% of cases. Thirty-day mortality was significantly higher in non-VQI vs VQI-eligible OAR cases (10% vs 4%; P = .04). CONCLUSIONS: Complex OAR comprises a majority of OAR cases in a contemporary tertiary referral hospital, yet these cases are not accounted for in the VQI. Creation of a "complex OAR" VQI module would capture these cases in a quality-driven national registry and help to better inform benchmarks for volume and outcomes in aortic surgery.

Limb-based patency as a measure of effective revascularization for chronic limb-threatening ischemia.

OBJECTIVE: In 2019, the Global Vascular Guidelines on chronic limb-threatening ischemia (CLTI) introduced the concept of limb-based patency (LBP) defined as maintained patency of a target artery pathway after intervention. The purpose of this study was to investigate the relationship between LBP and major adverse limb events (MALE) after infrainguinal revascularization for CLTI. METHODS: Consecutive patients undergoing revascularization for CLTI between 2016 and 2019 at a single tertiary institution with a dedicated limb preservation team were included. Subjects with aortoiliac disease, prior infrainguinal stents, or existing bypass grafts were excluded. Demographics, Global Limb Anatomic Staging System scores, Wound, Ischemia, foot Infection (WIfI) stages, revascularization details, and limb-specific outcomes were reviewed. LBP was defined by the absence of reintervention, occlusion, critical stenosis (>70%), or hemodynamic compromise with ongoing symptoms of CLTI. MALE included thrombectomy or thrombolysis, new bypass, open surgical graft revision and/or major amputation. RESULTS: We analyzed 184 unique limbs in 163 patients. This cohort was composed of 66.9% male patients with a mean age of 72 years. Baseline characteristics included diabetes (66%), tissue loss (91%), and advanced WIfI stages (30% stage 3, 51% stage 4). Global Limb Anatomic Staging System stage 3 anatomic patterns were common (n = 119 [65%]). Sixty limbs were treated with open bypass (65% involving tibial targets) and 124 underwent endovascular intervention (70% including infrapopliteal targets). The 12-month freedom from MALE and loss of LBP were 74.0% ± 3.7% and 48.6% ± 4.2%, respectively. Diabetes (hazard ratio [HR], 2.56; 95% confidence interval [CI], 1.13-5.83; P = .025) and loss of LBP (HR, 4.12; 95% CI, 1.96-8.64; P < .001) were independent predictors of MALE in a Cox proportional hazard model. Loss of LBP was the sole independent predictor of major limb amputation after revascularization (HR, 4.97; 95% CI, 1.89-13.09; P = .001). Loss of LBP impacted both intermediate-risk limbs (HR, 2.85; 95% CI, 1.02-7.97; P = .047 in WIfI stages 1-3) and high-risk limbs (HR, 3.99; 95% CI, 1.32-12.11; P = .014 in WIfI stage 4). However, the loss of LBP had the greatest impact on patients presenting with WIfI stage 4 disease (31% vs 8% major limb amputation at 12 months in limbs without vs with maintained LBP). CONCLUSIONS: The anatomic durability of revascularization, as measured by LBP, is a key determinant of treatment outcomes in CLTI regardless of the initial mode of intervention undertaken. Loss of LBP is most detrimental in patients presenting with advanced limb threat (WIfI stage 4).

Pedal arterial calcification score is associated with hemodynamic change and major amputation after infrainguinal revascularization for chronic limb-threatening ischemia.

OBJECTIVE: Pedal medial arterial calcification (pMAC) is associated with major amputation in patients with chronic limb-threatening ischemia (CLTI). We hypothesize that this association would be related to unresolved distal ischemia. We investigated relationships across pMAC score, hemodynamic change, and major amputation after infrainguinal revascularization for CLTI. METHODS: This is a single-institution, retrospective study of 306 patients who underwent technically successful infrainguinal revascularization for CLTI (2011-2020) and had foot x-rays for blinded pMAC scoring (0-5). A total of 136 (44%) patients had toe pressure measurements performed within 90 days before and 60 days after revascularization. Ischemia grade (0-3) was assigned using the Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) system. RESULTS: The revascularization approach was open bypass in 118 (38%) and endovascular in 188 (62%) patients. pMAC scores were trichotomized (0-1 [125; 41%], 2-4 [116; 38%], 5 [65; 21%]). Post-revascularization WIfI ischemia grade was improved in 78 of 136 (57%) and unchanged/worsened in 58 of 136 (43%). A lower pMAC score was associated with hemodynamic improvement (P = .004). Failure to improve the ischemia grade was associated with major amputation (P = .0002). In the endovascular subgroup, WIfI ischemia grade was improved in 43 of 90 (48%) with available measurements, and 37 of 188 (20%) underwent major amputation. In a multivariate logistic model, pMAC 5 was the only factor independently associated with unimproved ischemia grade after endovascular treatment (odds ratio: 4.0 [1.1-16.6], P = .04). In a Cox proportional hazards model, factors independently associated with major amputation after endoluminal revascularization were WIfI stage 4 (hazard ratio [HR]: 2.7 [1.3-5.7], P = .007) and pMAC score (pMAC: 2-4: HR: 10.6 [1.4-80.7], P = .02; pMAC: 5: HR: 15.5 [2.0-119], P = .008). In the bypass subgroup, WIfI ischemia grade was improved in 35 of 46 (76%) with available measurements but was not associated with pMAC score (P = .88) or any other baseline patient or limb characteristics. A total of 19 of 118 (16%) patients underwent major amputation. In a Cox proportional hazards model including bypass conduit, WIfI stage, and pMAC score, the only factor independently associated with major amputation after bypass was use of nonautologous conduit (HR: 5.6 [1.8-17.6], P = .003). CONCLUSIONS: The pMAC score is independently associated with persistent distal ischemia and major amputation after technically successful revascularization for CLTI. These data suggest that pMAC may be a marker for hemodynamic response to revascularization and risk of limb loss, and it may have a stronger influence on the outcome of endoluminal interventions.

Long-term Lower Extremity and Cardiovascular Complications after Simultaneous Pancreas-Kidney Transplant.

Lower extremity (LE) vascular disease and adverse cardiovascular events (ACEs) cause significant long-term morbidity after simultaneous pancreas-kidney (SPK) transplantation. This study's purpose was to describe the incidence of, and risk factors associated with, LE vascular complications and related ACEs following SPK. All SPKs performed at the authors' institution from 2000 to 2019 were retrospectively analyzed. The primary outcome was any LE vascular event, defined as LE endovascular intervention, open surgery, amputation, or invasive podiatry intervention. Secondary outcomes included post-SPK ACE. A total of 363 patients were included, of whom 54 (14.9%) required at least one LE vascular intervention following SPK. Only 3 patients received pre-SPK ankle brachial indices (ABIs). A history of peripheral artery disease (PAD) (HR 2.95, CI 1.4-6.2) was a risk factor for post-SPK LE vascular intervention even after adjustment for other factors. Fifty-nine (16.3%) patients experienced an ACE in follow-up. Requiring a LE intervention post-SPK was associated with a subsequent ACE (HR 2.3, CI 1.2-4.5). LE vascular and cardiovascular complications continue to be significant sources of morbidity for SPK patients, especially for patients with preexisting PAD. The highest risk patients may benefit from more intensive pre- and post-SPK workup with ABIs and follow-up with a vascular surgeon.

Dimerization and structure formation of colloids via capillarity at curved fluid interfaces.

Capillary interactions are ubiquitous between colloids trapped at fluid interfaces. Generally, colloids in fluid interfaces have pinned, undulated contact lines that distort the interface around them. To minimize the area, and therefore the energy of these distortions, colloids interact and assemble in a manner that depends on the shape of the host interface. On curved interfaces, capillary interactions direct isolated colloid motion along deviatoric curvature gradients. This directed motion relies on the leading order, long-ranged quadrupolar distortions made by the colloids' undulated pinned contact lines. Here we study pair interactions and dimer formation of colloids on non-uniformly curved fluid interfaces. Pair interaction energies are inferred to be order of 104kBT, and interacting forces are of order 10-1 pN for 10 micron particles adsorbed on interfaces formed around a 250 micron micropost. We compare experiments to analysis for the pair interaction energy, and identify criteria for dimers to form. We also study the formation of trapped structures by multiple particles to discern the influence of the underlying interface shape and the contact line undulations. By comparison to Monte Carlo simulations with potentials of interactions based on analysis, we find that higher order terms in the distortion fields generated by the particles play a major role in the structure formation on the curved interface. These interactions are determined by the particle's contact line and the host interface shape, and can be used to assemble particles independent of their material properties.

Elastocapillary interactions on nematic films.

Rod-like colloids distort fluid interfaces and interact by capillarity. We explore this interaction at the free surface of aligned nematic liquid crystal films. Naive comparison of capillary and elastic energies suggests that particle assembly would be determined solely by surface tension. Here, we demonstrate that, under certain circumstances, the capillary and elastic effects are complementary and each plays an important role. Particles assemble end-to-end, as dictated by capillarity, and align along the easy axis of the director field, as dictated by elasticity. On curved fluid interfaces, however, curvature capillary energies can overcome the elastic orientations and drive particle migration along curvature gradients. Domains of dominant interaction and their transition are investigated.

Curvature-driven assembly in soft matter.

Control over the spatial arrangement of colloids in soft matter hosts implies control over a wide variety of properties, ranging from the system's rheology, optics, and catalytic activity. In directed assembly, colloids are typically manipulated using external fields to form well-defined structures at given locations. We have been developing alternative strategies based on fields that arise when a colloid is placed within soft matter to form an inclusion that generates a potential field. Such potential fields allow particles to interact with each other. If the soft matter host is deformed in some way, the potential allows the particles to interact with the global system distortion. One important example is capillary assembly of colloids on curved fluid interfaces. Upon attaching, the particle distorts that interface, with an associated energy field, given by the product of its interfacial area and the surface tension. The particle's capillary energy depends on the local interface curvature. We explore this coupling in experiment and theory. There are important analogies in liquid crystals. Colloids in liquid crystals elicit an elastic energy response. When director fields are moulded by confinement, the imposed elastic energy field can couple to that of the colloid to define particle paths and sites for assembly. By improving our understanding of these and related systems, we seek to develop new, parallelizable routes for particle assembly to form reconfigurable systems in soft matter that go far beyond the usual close-packed colloidal structures.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'.

Smectic Gardening on Curved Landscapes.

Focal conic domains (FCDs) form in smectic-A liquid crystal films with hybrid anchoring conditions with eccentricity and size distribution that depend strongly on interface curvature. Assemblies of FCDs can be exploited in settings ranging from optics to material assembly. Here, using micropost arrays with different shapes and arrangement, we assemble arrays of smectic flower patterns, revealing their internal structure as well as defect size, location, and distribution as a function of interface curvature, by imposing positive, negative, or zero Gaussian curvature at the free surface. We characterize these structures, relating free surface topography, substrate anchoring strength, and FCD distribution. Whereas the largest FCDs are located in the thickest regions of the films, the distribution of sizes is not trivially related to height, due to Apollonian tiling. Finally, we mold FCDs around microposts of complex shape and find that FCD arrangements are perturbed near the posts, but are qualitatively similar far from the posts where the details of the confining walls and associated curvature fields decay. This ability to mold FCD defects into a variety of hierarchical assemblies by manipulating the interface curvature paves the way to create new optical devices, such as compound eyes, via a directed assembly scheme.

Shape-controlled orientation and assembly of colloids with sharp edges in nematic liquid crystals.

The assembly of colloids in nematic liquid crystals via topological defects has been extensively studied for spherical particles, and investigations of other colloid shapes have revealed a wide array of new assembly behaviors. We show, using Landau-de Gennes numerical modeling, that nematic defect configurations and colloidal assembly can be strongly influenced by fine details of colloid shape, in particular the presence of sharp edges. For cylinder, microbullet, and cube colloid geometries, we obtain the particles' equilibrium alignment directions and effective pair interaction potentials as a function of simple shape parameters. We find that defects pin at sharp edges, and that the colloid consequently orients at an oblique angle relative to the far-field nematic director that depends on the colloid's shape. This shape-dependent alignment, which we confirm in experimental measurements, raises the possibility of selecting self-assembly outcomes for colloids in liquid crystals by tuning particle geometry.

Curvature capillary migration of microspheres.

We address the question: how does capillarity propel microspheres along curvature gradients? For a particle on a fluid interface, there are two conditions that can apply at the three phase contact line: either the contact line adopts an equilibrium contact angle, or it can be pinned by kinetic trapping, e.g. at chemical heterogeneities, asperities, or other pinning sites on the particle surface. We formulate the curvature capillary energy for both scenarios for particles smaller than the capillary length and far from any pinning boundaries. The scale and range of the distortion made by the particle are set by the particle radius; we use singular perturbation methods to find the distortions and to rigorously evaluate the associated capillary energies. For particles with equilibrium contact angles, contrary to the literature, we find that the capillary energy is negligible, with the first contribution bounded to fourth order in the product of the particle radius and the deviatoric curvature of the host interface. For pinned contact lines, we find curvature capillary energies that are finite, with a functional form investigated previously by us for disks and microcylinders on curved interfaces. In experiments, we show microspheres migrate along deterministic trajectories toward regions of maximum deviatoric curvature with curvature capillary energies ranging from 6 × 10(3)-5 × 10(4)kBT. These data agree with the curvature capillary energy for the case of pinned contact lines. The underlying physics of this migration is a coupling of the interface deviatoric curvature with the quadrupolar mode of nanometric disturbances in the interface owing to the particle's contact line undulations. This work is an example of the major implications of nanometric roughness and contact line pinning for colloidal dynamics.

Resilience and depressive symptoms in mainland Chinese immigrants to Hong Kong.

PURPOSE: Immigrants are highly vulnerable to the development of psychological problems such as depressive symptoms, which calls for further study of immigration in the Eastern context. Identification of factors that protect against depressive symptoms would inform interventions to enhance immigrant adaptation. METHODS: This survey recruited 1,205 individuals who are adult immigrants from mainland China to Hong Kong. The Patient Health Questionnaire-9 (PHQ-9) was used to screen them for depressive symptoms. Participants also completed assessments for acculturative stress, discrimination and rejection, and personal and family resilience. RESULTS: The results showed that participants reported considerable depressive symptoms. After controlling for socio-demographic characteristics, acculturative stress, and discrimination and rejection, personal resilience was associated with fewer depressive symptoms. Family resilience added significant explanation of variance to predict depressive symptoms over and above the individual variables, including personal resilience. CONCLUSIONS: Our findings draw attention to the role of resilience as a protective factor against mental distress when facing adversities, while highlighting the central importance of family as an emotional resource for immigrant adjustment in the Chinese context. As personal resilience can increase with interventions, our results can inform trials to enhance adaptation among mainland Chinese immigrants in Hong Kong.

A Randomized Controlled Trial of Two Parenting Interventions on Enhancing Parental Resilience Resources and Reducing Children's Problem Behaviors in Chinese Cross-Boundary Families: Positive Benefits and Moderation Effects.

Daily cross-boundary schooling between Shenzhen and Hong Kong constitutes a constant challenge for Chinese cross-boundary families in terms of parenting burden. To address their most urgent parenting needs, we adapted and evaluated two intervention approaches-improving emotional regulation and providing knowledge about Hong Kong. A cluster randomized controlled trial with repeated assessments (pre-, post-intervention, and one-month follow-up) was adopted to evaluate the intervention effects on the increases of parental resilience resources and reduction of children's problem behaviors. We further conducted moderation analyses to investigate whether parents with more increases in parental resilience resources would report a greater reduction in children's problem behaviors. A total of 214 mothers of cross-boundary families were randomly assigned to the emotional regulation arm (ER, n = 120) or the information provision arm (IP, n = 94). Both intervention arms showed positive effects on emotional regulation strategies, and the IP arm outperformed the ER arm in knowledge acquisition. Both arms showed significant and comparable improvements in parental self-efficacy and children's problem behaviors. Moreover, participants in the IP arm who reported more improvements in parental resilience resources showed a greater reduction in children's problem behaviors. By adapting two interventions to a new population of cross-boundary families, this trial extended the benefits from parents to children and demonstrated that the improvement of parental resilience resources makes a difference in reducing children's problem behaviors in the IP arm. Future studies are suggested to focus on parental resilience resources and maximize the benefits on children's outcomes.

A Randomized Controlled Trial of Two Parent-Child Parallel Interventions to Enhance Positive Adaptation of Immigrant Families in Hong Kong: The Moderating Role of Depressive Symptoms.

Parents and children who have recently immigrated from the Chinese mainland to Hong Kong face various challenges, including psychological and sociocultural adaptation difficulties. In collaboration with community partners, our research team has developed and implemented culturally sensitive and preventive parent-child parallel interventions to enhance positive adaptation among immigrant parents and children. Two interventions were conducted in this randomized controlled trial: an emotion regulation (ER) arm, which addressed psychological adaptation by reducing parent-child conflicts and improving emotions, and an information provision (IP) arm targeting sociocultural adaptation by increasing participants' knowledge about Hong Kong. The study randomly assigned 113 and 73 parent-child pairs (allocation ratio 3:2) into the ER and IP arms, respectively. Parents and children attended four two-hour weekly sessions of their assigned intervention and completed assessments before, immediately after, and one month following the intervention. The results showed that in the ER arm, parents showed improved positive affect, and children reported decreases in parent-child conflicts more than their counterparts in the IP arm. In the IP arm, parents and children increased their knowledge, and parents decreased sociocultural adaptation difficulties more than their counterparts in the ER arm. In addition, the moderation analyses showed that in both interventions, parents and children with elevated baseline depressive symptoms obtained greater benefits relative to their counterparts with fewer symptoms. Such marked improvements were seen among parents in negative affect and adaptation difficulties and among children in parent-child conflict, positive and negative affect in the ER arm. More improvements were noted among parents in negative affect and sociocultural adaptation difficulties and among children in negative affect in the IP arm. Future studies are suggested to develop and provide parent-child parallel interventions targeting both psychological and sociocultural adaptations to parents and children with heightened baseline depressive symptoms to facilitate their positive adaptation in Hong Kong.