Photochemically responsive polymer films enable tunable gliding flights.

Miniaturized passive fliers based on smart materials face challenges in precise control of shape-morphing for aerodynamics and contactless modulation of diverse gliding modes. Here, we present the optical control of gliding performances in azobenzene-crosslinked liquid crystal networks films through photochemical actuation, enabling reversible and bistable shape-morphing. First, an actuator film is integrated with additive constructs to form a rotating glider, inspired by the natural maple samara, surpassing natural counterparts in reversibly optical tuning of terminal velocity, rotational rate, and circling position. We demonstrate optical modulation dispersion of landing points for the photo-responsive microfliers indoors and outdoors. Secondly, we show the scalability of polymer film geometry for miniature gliders with similar light tunability. Thirdly, we extend the material platform to other three gliding modes: Javan cucumber seed-like glider, parachute and artificial dandelion seed. The findings pave the way for distributed microflier with contactless flight dynamics control.

Screen Time Among Medical and Nursing Students and Its Correlation With Sleep Quality and Attention Span: A Cross-Sectional Study.

BACKGROUND:  Screen time is increasing among students and is also known to affect their lifestyle and health. The study investigated the correlation of screen time with sleep quality and attention span. METHODS: A cross-sectional study was conducted among undergraduate medical and nursing students in November 2021. A total of 192 students were selected randomly and investigated using a structured questionnaire. Sleep behavior was assessed using the Pittsburg Sleep Quality Index. Screen time and attention span were measured for each participant. The screen time data was reported as the median with an IQR. Pearson's correlation was performed to assess the correlation between screen time and sleep behavior and screen time and attention span. RESULTS:  The median screen time for 28 days was 260 (192.2-326.7) hours, and the median non-academic screen time was 250.0 (172.3-328.0) hours. Subjective sleep quality was good among 163 (84.9%) of the study participants. Global sleep quality was poor among 91 (42.2%) participants. The median score of the digit span forward was 6.00 (IQR: 5.00-7.00), and the median score of the digit span backward was 5.00 (IQR: 4.00-6.00). The global sleep score had a strong positive correlation with screen time, with a Pearson's correlation coefficient of 0.86. Forward and backward attention spans were not correlated with sleep scores, with correlation coefficients of 0.037 and 0.071, respectively. CONCLUSION:  Screen time is increasing significantly among medical and nursing undergraduate students, and their sleep is also getting affected. Emphasis should be given to the balance between digitalization and health.

Three-dimensional blueprinting of molecular patterns in liquid crystalline polymers.

Exploiting the interplay of anisotropic diamagnetic susceptibility of liquid crystalline monomers and site selective photopolymerization enables the fabrication of 3D freeforms with highly refined microstructures. Utilizing chain transfer agents in the mesogenic inks presents a pathway for broadly tuning the mechanical properties of liquid crystalline polymers and their response to stimuli. In particular, the combination of 1,4-benzenedimethanethiol and tetrabromomethane is shown to enable voxelated blueprinting of molecular order, while allowing for a modulation of the crosslink density and the mechanical properties. The formulation of these monomers allows for the resolution of the voxels to approach the limits set by the coherence lengths defined by the anchoring from surfaces. These compositions demonstrate the expected thermotropic responses while allowing for their functionalization with photochromic switches to elicit photomechanical responses. Actuation strains are shown to outstrip that accomplished with prior systems that did not access chain transfer agents to modulate the structure of the macromolecular network. Test cases of this system are shown to create freeform actuators that exploit the refined director patterns during high-resolution printing. These include topological defects, hierarchically-structured light responsive grippers, and biomimetic flyers whose flight dynamics can be actively modulated via irradiation with light.

A dimensionally-reduced nonlinear elasticity model for liquid crystal elastomer strips with transverse curvature.

Liquid crystalline elastomers (LCEs) are active materials that are of interest due to their programmable response to various external stimuli such as light and heat. When exposed to these stimuli, the anisotropy in the response of the material is governed by the nematic director, which is a continuum parameter that is defined as the average local orientation of the mesogens in the liquid crystal phase. This nematic director can be programmed to be heterogeneous in space, creating a vast design space that is useful for applications ranging from artificial ligaments to deployable structures to self-assembling mechanisms. Even when specialized to long and thin strips of LCEs - the focus of this work - the vast design space has required the use of numerical simulations to aid in experimental discovery. To mitigate the computational expense of full 3-d numerical simulations, several dimensionally-reduced rod and ribbon models have been developed for LCE strips, but these have not accounted for the possibility of initial transverse curvature, like carpenter's tape spring. Motivated by recent experiments showing that transversely-curved LCE strips display a rich variety of configurations, this work derives a dimensionally-reduced 1-d model for pre-curved LCE strips. The 1-d model is validated against full 3-d finite element calculations, and it is also shown to capture experimental observations, including tape-spring-like localizations, in activated LCE strips.

Posterior superior alveolar nerve block alone in the extraction of upper third molars: a prospective clinical study.

Background: Third molar extraction is the most commonly performed minor oral surgical procedure in outpatient settings and requires regional anesthesia for pain control. Extraction of the maxillary molars commonly requires both posterior superior alveolar nerve block (PSANB) and greater palatine nerve block (GPNB), depending on the nerve innervations of the subject teeth. We aimed to study the effectiveness of PSANB alone in maxillary third molar (MTM) extraction. Methods: A sample size comprising 100 erupted and semi-erupted MTM was selected and subjected to study for extraction. Under strict aseptic conditions, the patients were subjected to the classical local anesthesia technique of PSANB alone with 2% lignocaine hydrochloride and adrenaline 1:80,000. After a latency period of 10 min, objective assessment of the buccal and palatal mucosa was performed. A numerical rating scale and visual analog scale were used. Results: In the post-latency period of 10 min, the depth of anesthesia obtained in our sample on the buccal side extended from the maxillary tuberosity posteriorly to the mesial of the first premolar (15%), second premolar (41%), and first molar (44%). This inferred that anesthesia was effectively high until the first molars and was less effective further anteriorly due to nerve innervation. The depth of anesthesia on the palatal aspect was up to the first molar (33%), second molar (67%), and lateromedially; 6% of the patients received anesthesia only to the alveolar region, whereas 66% received up to 1.5 cm to the mid-palatal raphe. In 5% of the cases, regional anesthesia was re-administered. An additional 1.8 ml PSANB was required in four patients, and another patient was administered a GPNB in addition to the PSANB during the time of extraction and elevation. Conclusion: The results of our study emphasize that PSANB alone is sufficient for the extraction of MTM in most cases, thereby obviating the need for poorly tolerated palatal injections.

Late-Onset Bartter's Syndrome Type II with End-Stage Renal Disease Due to a Novel Mutation in KCNJ1 Gene in an Indian Adult Male - A Case Report.

Mutations in ROMK1 potassium channel gene (KCNJ1) causes antenatal/neonatal Bartter's syndrome type II, which presents with renal salt wasting, hypokalemic metabolic alkalosis, secondary hyperaldosteronism, hypercalciuria, and nephrocalcinosis. We herein describe a case of late-onset Bartter's syndrome type II with progressive renal failure requiring renal replacement therapy secondary to a novel homozygous missense mutation in Exon 2 of KCNJ1 gene (c.500G>A). With this case, we aim to highlight the need for a high index of suspicion and the role of genetic evaluation to diagnose clinically unclassified cases of nephrocalcinosis with renal electrolyte abnormalities more so in late and atypical presentations.

Effect of Preemptive Multimodal Analgesia Regimen on Post-operative Epidural Demand Boluses in Lower Limb Orthopaedic Surgeries.

Introduction Excruciating pain is associated with lower limb orthopaedic surgeries involving femoral shaft fractures. Postoperative pain management is still ineffective in low-resource settings where the use of epidural and opioid-free analgesia is impractical. Literature is scarce with respect to the effect of a preemptive multimodal analgesia regimen on the requirement of postoperative epidural demand boluses. Hence, the present study aimed to evaluate the effect of pre-emptive multimodal analgesia in reducing the requirement of epidural demand boluses postoperatively, and to find out the time required to receive the first epidural bolus. Material and methods This double-blinded randomized control study included 48 subjects. Patients aged 18-60 years with lower limb fractures requiring surgery under combined spinal-epidural anesthesia were included. Patients were divided into two groups through random allocation. Group A: Preemptive multimodal group received intravenous paracetamol 1 g, IV diclofenac 75 mg diluted in 100ml NS, IV tramadol 50 mg diluted in 100ml NS and tab pregabalin 75 mg orally, 30 mins before surgery. Group B: Placebo group received 3 pints of 100ml NS IV and tab ranitidine 150 mg, 30 mins before surgery. Intraoperatively, combined spinal-epidural anaesthesia was administered taking all the aseptic precautions. Visual analogue scale (VAS) was recorded immediately on shifting to a postoperative room, and then at 1, 4, 8, 12, and 24 hr for both groups. Epidural boluses (10 ml of 0.125% bupivacaine with 2 µg/ml of fentanyl) were given whenever the patient's visual analogue scale was more than 4. The time at which the first epidural bolus was required by the patient was recorded. The total number of epidural boluses given over 24 hours based on VAS was recorded for both, the preemptive and placebo groups. If the patient still complained of pain, IV diclofenac 75 mg was given if the VAS was more than 4, while IV diclofenac 75 mg along with IV tramadol 50 mg was given if the VAS was more than 6. Patient satisfaction with anesthesia care, in general, was assessed 24 hrs postoperatively. Results A total of 48 subjects were included in the study. During the immediate-postoperative period, and at 8, 12 and 24 hr, the median VAS was significantly low in group A as compared to group B. A significant increase in the demand for epidural bolus immediate-postoperatively was observed in group B (70.83%) compared to group A (4.17%) (p-value of <0.001). At 8 hr, 12hr, and 24hr, patients in group A found a significantly less need for epidural boluses compared to Group B. The mean total number of epidural boluses taken in group A was significantly less compared to group B (1.79 ± 0.41 VS 3.33 ± 0.48, p-Value <0.001). In group A, all patients reported no requirement for diclofenac and tramadol. In group B, 8.33% required diclofenac 75 mg, while the remaining 91.66% had no requirement for diclofenac and tramadol. The difference in patient satisfaction with anaesthesia care in general between the two study groups was found to be significant with a p-value of 0.027. Patients in Group A were very satisfied compared with those in group B. Conclusions The study found that the pre-emptive multimodal analgesia group had better postoperative pain control because they required fewer epidural boluses and no extra analgesics postoperatively. This group was more satisfied with the anaesthesia care in general.

Rate of Recovery and Symptomatic Efficacy of a Polyherbal AYUSH Formulation in the Treatment of SARS-CoV-2 Disease: A Single-arm Trial.

Background: The COVID-19 pandemic, caused by the human coronavirus, SARS-CoV-2, has led to the death of millions across the globe. The SARS-CoV-2 virus is highly infectious, and mutates rapidly. This creates additional challenges for the development of robust therapeutic solutions. Along with modern healthcare, there is a need to explore natural, plant-based antiviral compounds that can be used in the treatment of COVID-19. Objective: The present feasibility study investigates the efficacy of a 13-ingredient Ayurvedic polyherbal formulation, NOQ19, in the management of COVID-19. Methodology: A single-arm, open-label study design was adopted for this feasibility study. 161 RT-PCR-positive COVID-19 patients were enrolled. The enrolled participants were provided with the Ayurvedic intervention - two tablets of NOQ19 thrice daily along with the standard of care treatment. Follow-up COVID-19 RT-PCR tests were conducted on days 5, 10, and 14 or until the patient tested negative. The time taken to turn RT-PCR negative or become asymptomatic was noted. Setting: The study was conducted at Sri Sri Institute for Advanced Research from April 2021 to June 2021. Participants: A total of 161 COVID-19 patients isolating at home were assessed. Intervention: The NOQ19 preparation is a combination of 13 Ayurvedic herbs. Outcomes Measured: RT-PCR tests, the turnaround time to becoming asymptomatic, and regular symptoms assessment. Results: The analysis demonstrated that 74% of the patients tested negative on the RT-PCR within five days of taking NOQ19. Additionally, 98% of the subjects tested negative on the RT-PCR on day 10 after taking NOQ19 and standard of care treatment (as necessary). None of the participants reported any adverse events or side-effects due to NOQ19 medication. Conclusion: The NOQ19 Ayurvedic polyherbal formulation can be an effective and safe option for the symptomatic management of COVID-19.

Primary Sjögren's Syndrome Presenting as Cerebral Venous Thrombosis: A Rare Case.

Sjogren's syndrome is a late-onset, slowly progressing autoimmune disease characterized by the destruction of the exocrine glands by lymphocytic infiltration, resulting in dry mouth (xerostomia) and dry eyes (keratoconjunctivitis sicca). Sjögren's syndrome may be associated with various autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, and systemic sclerosis. We report a case of a 34-year-old female who delivered a live baby 20 days ago. She presented in a postictal state after two episodes of tonic-clonic movements of limbs with altered sensorium with a history of headache for seven days. Further evaluation revealed that the subject had a history of multiple abortions and grittiness in her eyes. MRI showed signs of infarction in the left parietal lobe and magnetic resonance venography (MRV) suggested cavernous venous thrombosis. After an unwavering effort to rule out alternate causes, the rare correlation between primary Sjogren's syndrome and cerebral venous thrombosis was considered. Additional investigations were performed, which showed the patient to be positive for Anti SS-A (Ro52), Anti SS-B (La), and anti-centromere antibodies. The patient gradually improved with anti-edema measures and steroids and was discharged by day nine. We present this case to emphasize the neurological manifestation of Sjogren's syndrome, which may present as cerebral venous thrombosis.

Fibrinogen Levels in Type 2 Diabetes Mellitus and it's Correlation with Microvascular Microvascular Complications.

Diabetes mellitus comprises a group of common metabolic disorders that share the phenotype of hyperglycemia the potential role of hemostatic factors, particularly fibrinogen, in atherosclerosis and its complications has generated considerable attention. Fibrinogen, itself is determined by several modifiable and non-modifiable determinants like age, sex, smoking, body mass index (BMI), hypertension, alcoholism, glycemic control, lipid profile and urine albumin excretion rate. The present study is undertaken to know the levels of fibrinogen in type 2 diabetes mellitus and its relation with microvascular complications. MATERIAL: This is a cross section observational study. All patients, admitted to our hospital, who where a known case of Type 2 Diabetes mellitus where tested for fibrinogen levels and other investigations such as CBC, urine routine and ACR, Fundoscopy during the month of April 2020 to June 2021and were included in the study. All characteristics were summarized descriptively. For continuous variables, the summary statistics of mean, standard deviation (SD) were used. For categorical data, the number and percentage were used in the data summaries. Chi-square (χ2)/ Freeman Halton Fisher exact test was employed to determine the significance of differences between groups for categorical data. The difference of the means of analysis variables between two independent groups was tested by unpaired t test. The difference of the means of analysis variables between more than two independent groups was tested by ANOVA and F test of testing of equality of Variance. If the pvalue was < 0.05, then the results were considered to be statistically significant. OBSERVATION: A total of 70 patients were studied. The mean age was 45 years with a male preponderance of 61%. Of the total 70 studied, It was noted that in diabetics the mean fibrinogen level was very high (611mg/dl) which was observed to be very highly significant (p value <0.05). The duration of diabetes was more than 5 years in majority of cases that is 29 cases with mean duration of diabetes 7.5 years. Fibrinogen level was significantly correlated with HbA1C (p <0.05), urine albumin excretion measured by microalbuminuria (p< 0.05). Fibrinogen level was significantly higher in patients with retinopathy (p<0.05). ANOVA / Unpaired t test were used which showed duration of diabetes (p value <0.05)and microalbuminuria (p value < 0.05) to be independent risk factors. CONCLUSION: A significant association between fibrinogen levels and albumin excretion rate measured by micro albiminuria was documented . Because microalbiminuria is a well recognized powerful predictor of cardiovascular related illness and death in diabetes, fibrinogen levels can be considered as a potential additional risk fctor in patients with diabetes. On the basis of observation of this study, it may be conferred that hyperfibrinogenemia could be a mechanism of the increased micro and macrovascular risks faced by patients with Type 2 diabetes mellitus.

Long-term Persistence of Immunogenicity After Primary Vaccination and Response to Booster Vaccination With Typhoid Conjugate Vaccine: Results of a Phase IV Extension Study.

OBJECTIVE: To evaluate the persistence of antibodies three years after primary vaccination with typhoid conjugate vaccine (TCV) of either Cadila Healthcare Ltd. (Cadila-TCV) or Bharat Biotech International Ltd. (Bharat-TCV) administered in a previous phase II/III study, and to study the booster dose response to Cadila-TCV. METHODS: This was an open-label, phase IV extension study conducted in tertiary care and multispecialty hospitals in India. 112 subjects (Cadila-TCV-57, Bharat-TCV-55) who had participated in previous study were enrolled. Of these, eligible subjects received a single-dose of Cadila-TCV and were followed-up for 28 days post-booster. Primary outcome was persistence of antibodies 3 years after primary vaccination and seroconversion (≥4-fold rise in antibody titre from baseline) 28 days post-booster. Safety was based on reported adverse events (AEs) post-booster. RESULTS: The baseline GMT reported in the current study was significantly higher than pre-vaccination GMT reported in the previous study. 89/112 (79.5%) subjects had antibody titer ≥10 IU/mL at baseline; eligible subjects (n=17) who had baseline antibody titre <10 IU/mL were administered booster dose. All the vaccinated subjects showed seroconversion post-booster. The GMTs reported at 10 days and 28 days post-booster were significantly higher as compared to GMTs reported after primary vaccination in previous study. 4 (23.5%) vaccinated subjects reported 9 AEs; all were solicited and of mild/moderate intensity. CONCLUSIONS: There was a significant persistence of immunogenicity after primary vaccination with both the TCVs, and robust immune response after booster vaccination with Cadila-TCV.

Tracheobronchial Injury: Role of Virtual Bronchoscopy.

A tracheobronchial avulsion is a very rare and serious condition that occurs mostly due to blunt trauma chest caused by high-speed traffic accidents. In this article, we present a challenging case of a 20-year-old male who had a right tracheobronchial transection with carinal tear which was repaired on cardiopulmonary bypass (CPB) through right thoracotomy. Challenges faced and a review of literature will be discussed. How to cite this article: Kaur A, Singh VP, Gautam PL, Singla MK, Krishna MR. Tracheobronchial Injury: Role of Virtual Bronchoscopy. Indian J Crit Care Med 2022;26(7):879-880.

Sonographic assessment of diaphragmatic thickening and excursion as predictors of weaning success in the intensive care unit: A prospective observational study.

Background and Aims: Ultrasonographic assessment of diaphragmatic function can be a useful bedside tool in the weaning and extubation of mechanically ventilated patients, especially in patients with difficult weaning, in whom diaphragmatic weakness is suspected. Thus, this study was planned to assess the role of bedside sonographic assessment of diaphragmatic indices such as diaphragmatic thickening fraction (DTf) and diaphragmatic excursion (DE) in predicting successful extubation or extubation failure in weaning eligible patients by comparing the measurements with outcome. Methods: This prospective observational study was conducted on 50 mechanically ventilated, weaning-ready patients during the spontaneous breathing trial (SBT). The DE and DTf of patients were noted along with conventional parameters of weaning. Probability value <0.05 was considered statistically significant. Receiver operating characteristic (ROC) curves were used for analysis. Area under the curve (AUC) was measured, and sensitivity and specificity for different cut-off values were estimated. Results: Out of 50 patients, 15 (30%) had SBT failure and 4 had extubation failure. The group with SBT failure had significantly higher rapid shallow breathing index (RSBI) and airway occlusion pressure (P0.1s), whereas DE and DTf were lower compared to the SBT successful group. Strong correlation existed between RSBI, DTf, DE and P0.1s. DTf of nearly 24% (sensitivity 93.5%, specificity 94.7%) and DE of 1.10 cm (84% sensitivity, 89.5% specificity) were associated with best outcome. Conclusion: Along with conventional parameters of weaning, sonographic assessment of diaphragmatic parameters can be useful in predicting the success of SBT and in avoiding unnecessary extubation failures and thereby help in achieving a successful weaning outcome.

Correlation of Variables for WHARFE Assessment and Pederson Difficulty Index for Impacted Mandibular Third Molar Surgery-A Prospective Clinical Study.

OBJECTIVES: To assess the correlation of factors of WHARFE assessment and Pederson difficulty index for impacted mandibular third molar surgery. STUDY DESIGN: A comparative study of difficult factors utilizing Pederson WHARFE and WAR lines was performed involving patients undergoing surgical removal of mandibular third molars for 100 such teeth. RESULTS: The Spearman's rho correlation run to determine the relationship between Pederson difficulty index and WHARFE assessment values showed a strong, positive monotonic correlation at the 0.05 level (2-tailed; rs = 0.242, n = 100, p = 0.015 < 0.05). CONCLUSION: The study has revealed WHARFE assessment to be a more reliable and consistent measure for the radiological evaluation of surgical difficulty over the contemporary Pederson difficulty index.

Percutaneous Tracheostomy in COVID Era: Time to Adapt and Improvise.

BACKGROUND: Percutaneous dilatation tracheostomy (PDT) is required in patients with novel coronavirus disease-2019 (COVID-19) with severe respiratory involvement, but the procedure needs modification to minimize the risk of aerosol exposure to caregivers. AIM AND OBJECTIVE: To share the experience of apnea approach of PDT in COVID patients. Also, to demonstrate the safety of the technique for healthcare workers (HCWs) and patients with respect to hemodynamic and oxygenation parameters. The incidence of adverse events and difficulties during the procedure were also recorded. MATERIALS AND METHODS: According to this modified approach, percutaneous tracheostomy was performed with apnea technique during open tracheal steps (video attached) and the endotracheal tube was withdrawn to the level of cords under video-laryngoscopic guidance. STUDY DESIGN: A retrospective data analysis of all the tracheostomy procedures (PDT) performed with the apnea technique during the COVID era (June-September) in non-COVID and COVID patients in intensive care units (ICUs). RESULTS: During these 4 months, 74 PDT procedures were performed in both COVID and non-COVID patients in the ICUs of our hospital. Out of these, PDT with apnea technique was performed in 45 patients (61%). This technique was successful in 44 patients (97.7%) with mean apnea time of 110 + 8.6 seconds. There was no significant (p < 0.05) change in mean arterial pressure and oxygen saturation of 15 COVID patients in pre-PDT and immediate post-PDT period. None of the six team members performing PDT had symptoms or tested positive for COVID-19. CONCLUSION: PDT with apnea technique can be performed to minimize the risk of aerosol exposure and does not compromise the quality of care. It is safe both for the patient and HCWs. HOW TO CITE THIS ARTICLE: Paul G, Gautam PL, Sharma S, Sravani MV, Krishna MR. Percutaneous Tracheostomy in COVID Era: Time to Adapt and Improvise. Indian J Crit Care Med 2021;25(6):642-647.

Effect of coronavirus lockdowns on the ambient seismic noise levels in Gujarat, northwest India.

The Covid-19 pandemic created havoc and forced lockdowns in almost all the countries worldwide, to inhibit social spreading. In India as well, as a precautionary measure, complete and partial lockdowns were announced in phases during March 25 to May 31, 2020. The restricted human activities led to a drastic reduction in seismic background noise in the high frequency range of 1-20 Hz, representative of cultural noise. In this study, we analyse the effect of anthropogenic activity on the Earth vibrations, utilizing ambient noise recorded at twelve broadband seismographs installed in different environmental and geological conditions in Gujarat. We find that the lockdowns caused 1-19 dB decrease in seismic noise levels. The impact of restricted anthropogenic activities is predominantly visible during the daytime in urban areas, in the vicinity of industries and/or highways. A 27-79% reduction in seismic noise ground displacement (drms) is observed in daytime during the lockdown, in populated areas. However, data from station MOR reveals a drastic decrease in drms amplitude both during the day (79%) and night times (87%) since factories in this area operate round the clock. The noise at stations located in remote areas and that due to microseisms, shows negligible variation.

Thermomechanically active electrodes power work-dense soft actuators.

The effect of chain extender structure and composition on the thermomechanical properties of liquid crystal elastomers (LCE) synthesized using thiol-acrylate Michael addition is presented. The intrinsic molecular stiffness of the thiol chain extender and its relative molar ratio to acrylate-based host mesogens determine the magnitudes of the thermomechanical strains, temperatures at which they are realized and the mechanical work-content. A non-linear structure-property relationship emerges, wherein higher concentrations of flexible extenders first magnify the thermomechanical sensitivity, but a continued increase leads to weaker actuation. Understanding this interplay leads to a composite material platform, enabling a peak specific work production of ∼2 J kg-1 using ∼115 mW of electrical power supplied at 2 V. Composites of LCE with eGaIn liquid metal (LM) are prepared, which act as heaters, while being capable of actuation themselves. The thermomechanically active electrodes convert the electrical power into Joule heat, which they efficiently couple with the neat LCE to which they are bound. This system harnesses the nascent responsiveness of the LCE using electrodes that work with them, instead of fighting against them (or passively standing in the way). Specific work generated increases when subjected to increasing levels of load, reaching a peak at loads ∼260× the actuator weight. These ideas are extended to tri-layered actuators, where LCE films with orthogonal molecular orientations sandwich LCE-LM composite heaters. Torsional actuation modes are harnessed to twist under load.

Torque-dense photomechanical actuation.

Contactless actuation powered using light is shown to generate torque densities approaching 10 N m kg-1 at angular velocities ∼102 rad s-1: metrics that compare favorably against tethered electromechanical systems. This is possible even though the extinction of actinic light limits the characteristic thickness of photoresponse in polymers to tens of µm. Confinement of molecularly patterned developable shells fabricated from azobenzene-functionalized liquid crystalline polymers encodes torque-dense photoactuation. Photostrain gradients from unstructured irradiation segment this geometry into two oppositely curved regions connected by a curved crease. A monolithic curved shell spontaneously bifurcates into a jointed, arm-like mechanism that generates flexure over sweep angles exceeding a radian. Strain focusing at the crease is hierarchical: an integral crease nucleates at smaller magnitudes of the prebiased curvature, while a crease decorated with point-like defects emerges at larger curvatures. The phase-space of morphogenesis is traceable to the competition between stretch and bending energies and is parameterizable as a function of the geometry. The framework for generating repetitive torque-dense actuation from slender light-powered actuators holds broader implications for the design of soft, remotely operated machines. Here, it is harnessed in illustrative mechanisms including levers, lifters and grabbers that are powered and regulated exclusively using light.

Voxelated Molecular Patterning in Three-Dimensional Freeforms.

The ability to pattern material response, voxel by voxel, to direct actuation and manipulation in macroscopic structures can enable devices that utilize ambient stimuli to produce functional responses at length scales ranging from the micro- to the macroscopic. Fabricating liquid crystalline polymers (LCPs), where the molecular director is indexably defined in three-dimensional (3D) freeforms, can be a key enabler. Here, the combination of anisotropic magnetic susceptibility of the liquid crystalline monomers in a reorientable magnetic field and spatially selective photopolymerization using a digital micromirror device to independently define molecular orientation in light and/or heat-responsive multimaterial elements, which are additively incorporated into 3D freeforms, is exploited. This is shown to enable structural complexity across length scales in nontrivial geometries, including re-entrant shapes, which are responsive to either heat or light. A range of monomer compositions are optimized to include photoinitiators, light absorbers, and polymerization inhibitors to modulate the polymerization characteristics while simultaneously retaining the tailorability of the nematic alignment. The versatility of this framework is illustrated in an array of examples, including (i) thermomechanical generation of Gaussian-curved structures from flat geometries, (ii) light-responsive freeform topographies, and (iii) multiresponsive manipulators, which can be powered along independent axes using heat and/or light. The ability to integrate responses to multiple stimuli, where the principal directions of the mechanical output are arbitrarily tailored in a 3D freeform, enables new design spaces in soft robotics, micromechanical/fluidic systems, and optomechanical systems.

Geological evidence for AD 1008 tsunami along the Kachchh coast, Western India: Implications for hazard along the Makran Subduction Zone.

The 2004 Sumatra-Andaman tsunami emphasized the catastrophic nature of such disasters and exposed our knowledge gap of the historical and palaeo events. In the aftermath of this deadly event, the thrust in palaeotsunami studies was restricted to areas in the Indian Ocean, affected by this tsunami. The northern Arabian Sea, which hosts a similar tsunamigenic source i.e. the Makran Subduction Zone (MSZ), has so far remained 'Terra-Incognita'. Here, for the first time, we report geological evidence of the 1008 AD tsunami, also mentioned as 'an enigma' in the historical reports, by identifying a >250 km long sand sheet with a landward extent of more than 250 m from the Indian coastline. Detailed sedimentology and geochemistry reveals an offshore origin of this sand sheet, from where it was eroded by a high energy wave and deposited in a supratidal environment. Optical and AMS 14C chronology constrains its age of deposition around 1000 AD. The shear size of the sand sheet, laterally and across the coast, along with grain size, a characteristically different provenance, are some of the major indicators, which can be useful in palaeotsunami/palaeostorm deposit distinction. Our report of the AD 1008 event from the Indian coastline, also supports the claim that the Western MSZ, albeit at longer intervals, has experienced major thrust earthquakes (Mw > 8) in the historical past. The proximity of this sand sheet to the shoreline does not discount the role of extremely unlikely, large storms as its causal mechanism.