Effect of Heat Treatment on the Material Property and Cell Viability of Wire Arc Additively Manufactured Ti6Al4 V.

Wire arc additive manufacturing (WAAM) holds promise for producing medium to large industrial components. Application of WAAM in the manufacturing of biomedical materials has not yet been evaluated. The current study addresses two key research questions: first, the suitability of the WAAMed Ti6Al4V alloy for biomedical applications, and second, the effect of Ti6Al4V's constituents (α and ß phases) on the cell viability. The WAAMed Ti6Al4V alloy was fabricated (as-deposited: AD) using a metal inert gas (MIG)-based wire arc system using an in-house designed shielding chamber filled with argon. Subsequently, samples were subjected to solution treatment (950 °C for 1 h), followed by aging at 480 °C (T1), 530 °C (T2), and 580 °C (T3) for 8 h and subsequent normalization to ambient conditions. Microstructural analysis revealed ∼45.45% of α'-Ti colonies in the as-deposited samples, reducing to 23.26% postaging at 580 °C (T3). The α-lath thickness and interstitial oxygen content in the sample were observed to be proportional to the aging temperature, peaking at 580 °C (T3). Remarkably, during tribocorrosion analysis in simulated body fluid, the 580 °C-aged T3 sample displayed the lowest corrosion rate (7.9 µm/year) and the highest coefficient of friction (CoF) at 0.58, showing the effect of increasing oxygen content in the alloy matrix. Cell studies showed significant growth at 530 and 580 °C by day 7, correlated with higher oxygen content, while other samples had declining cell density. Additionally, optimal metallurgical property ranges were identified to enhance the Ti6Al4V alloy's biocompatibility, providing crucial insights for biomedical implant development.

Development of iodine based sustained release antimicrobial coatings for polyurethane voice prostheses.

Voice prostheses are known to fail in few weeks to several months of implantation due to the clogging mainly caused by microbial biofilm formation, which is a cause of concern. Iodine is a known broad-spectrum biocide and is reported to easily form complexes with various polymers. For long term device disinfection, strong iodine complexation that offers sustained iodine release for a prolonged period is essential. The present research work deals with the synthesis of a poly(methyl methacrylate-n-butyl acrylate-N-vinyl-2-pyrrolidone) (poly[MMA-BA-NVP]) tercopolymer through free radical polymerization for surface coating thermoplastic polyurethane (TPU) based voice prostheses. The NVP content in the tercopolymer was varied from 20% to 50% to optimise iodine loading and subsequent release. Base TPU coated with the tercopolymer was treated with 4% aqueous iodine solution at room temperature (28 ± 3 °C) for two hours. It was observed that the tercopolymer containing 35% N-vinyl-2-pyrrolidone (NVP), 32.5% methyl methacrylate (MMA) and 32.5% butyl acrylate (nBA) gave a stable coating on TPUs together with sustained iodine release for a prolonged period. Furthermore, the tercopolymer coated and iodine loaded TPUs exhibited excellent antimicrobial activity against Candida albicans, Staphylococcus aureus and Escherichia coli.

Rapid detection of Mucorales in human blood and urine samples by functionalized Heusler magnetic nanoparticle assisted customized loop-mediated isothermal amplification.

Mucormycosis is a rare disease with scarce diagnostic methods for early intervention. Available strategies employing direct microscopy using calcofluor white-KOH, culture, radiologic, and histopathologic testing often are time-intensive and demand intricate protocols. Nucleic Acid Amplification Test holds promise due to its high sensitivity combined with rapid detection. Loop-mediated isothermal amplification (LAMP) based detection offers an ultrasensitive technique that does not require complicated thermocyclers like in polymerase chain reaction, offering a straightforward means for improving diagnoses as a near-point-of-care test. The study introduces a novel magnetic nanoparticle-based LAMP assay for carryover contaminant capture to reduce false positives. Solving the main drawback of LAMP-based diagnosis techniques. The assay targets the cotH gene, which is invariably specific to Mucorales. The assay was tested with various species of Mucorales, and the limit of detections for Rhizopus microsporus, Lichtheimia corymbifera, Rhizopus arrhizus, Rhizopus homothallicus, and Cunninghamella bertholletiae were 1 fg, 1 fg, 0.1 pg, 0.1 pg, and 0.01 ng, respectively. This was followed by a clinical blindfolded study using whole blood and urine samples from 30 patients diagnosed with Mucormycosis. The assay has a high degree of repeatability and had an overall sensitivity of > 83%. Early Mucormycosis detection is crucial, as current lab tests from blood and urine lack sensitivity and take days for confirmation despite rapid progression and severe complications. Our developed technique enables the confirmation of Mucormycosis infection in < 45 min, focusing specifically on the RT-LAMP process. Consequently, this research offers a viable technique for quickly identifying Mucormycosis from isolated DNA of blood and urine samples instead of invasive tissue samples.

Mucormycosis is a challenging disease to diagnose early. This study introduces a sensitive and rapid diagnostic approach using Loop-mediated isothermal amplification technology. Testing blood and urine samples from 30 patients revealed promising sensitivity and repeatability, indicating its potential for non-invasive diagnosis.

Orthopedic Scaffolds: Evaluation of Structural Strength and Permeability of Fluid Flow via an Open Cell Neovius Structure for Bone Tissue Engineering.

The ability of bone to regenerate itself through mechanobiological responses is its dynamic property. Mechanical cues from a neighboring environment produce the structural strain to promote blood flow and bone marrow mobility that in turn aids the bone regeneration process. Occurrences of these phenomena are crucial for the success of metallic scaffolds implanted in the host bone tissue. Thus, permeability and fluid flow-induced wall shear stress (WSS) are two parameters that directly influence cell bioactivities inside a scaffold and are crucial for effective bone tissue regeneration. Given that the scaffolds shall be implanted in the body, permeability assessment was carried out using non-Newtonian fluid. In this work, the triply periodic minimal surface scaffolds with Neovius architectures were fabricated by using selective laser melting technology. The estimation of fluid flow was carried out using computational fluid dynamics (CFD) analysis with a non-Newtonian blood fluid model. Further, the structural strength of various open cell Neovius lattices was evaluated using a static compression test, and in vitro cell culture using Alamar blue assay was evaluated. Results revealed that the values of intrinsic blood flow permeability of the three-dimensional (3D)-printed open cell porous scaffold with Neovius architecture were of the same order of magnitude as those of human bone, ranging from 0.0025 × 10-9 to 0.0152 × 10-9 m2. The structural elastic modulus and compressive strength of NOCL40, NOCL50, and NOCL60 lattices range from 3.27 to 3.71 GPa and 194 to 205 MPa, respectively. All of the values are comparable to the human bone, thus making these lattices a suitable alternative for orthopedic applications.

Effect of SDF/ SSKI Application on Microtensile Bond Strength of Composite Resin to Carious Primary Dentin: An In Vitro Study.

PURPOSE: The purpose of this in vitro study was to investigate the effect of applying silver diamine fluoride (SDF) followed by a saturated solution of potassium iodide (SSKI) on the microtensile bond strength (mTBS) of composite resin to the natural carious dentin of primary molars. METHODS: Sixty-nine extracted carious primary molars were randomly allocated to one of the three groups, where the prepared affected dentin was treated with: (1) group A-SDF/SSKI; (2) group B-SDF alone; and (3) group C-deionized water. After restoration with composite resin restorative material, specimens were prepared and tested for mTBS in the universal testing machine. Median bond strengths were compared using the Kruskal-Wallis test. RESULTS: The median (range) values of mTBS in groups A, B, and C were 16.99 (6.55 to 95.60), 17.71 (4.93 to 101.1), and 24.60 (5.29 to 91.7) MPa, respectively. There was no statistically significant difference in the microtensile bond strength among the three groups (P=0.94). CONCLUSION: The application of either silver diamine fluoride along with a saturated solution of potassium iodide or SDF alone does not have a significant inhibitory effect on the bond strength of the composite resin to carious dentin in vitro.

Hydrogel nanosheets confined 2D rhombic ice: a new platform enhancing chondrogenesis.

Nanoconfinement within flexible interfaces is a key step towards exploiting confinement effects in several biological and technological systems wherein flexible 2D materials are frequently utilized but are arduous to prepare. Hitherto unreported, the synthesis of 2D hydrogel nanosheets (HNSs) using a template- and catalyst-free process is developed representing a fertile ground for fundamental structure-property investigations. In due course of time, nucleating folds propagating along the edges trigger co-operative deformations of HNS generating regions of nanoconfinement within trapped water islands. These severely constricting surfaces force water molecules to pack within the nanoscale regime of HNS almost parallel to the surface bringing about phase transition into puckered rhombic ice with AA and AB Bernal stacking pattern, which was mostly restricted to molecular dynamics studies so far. Interestingly, under high lateral pressure and spatial inhomogeneity within nanoscale confinement, bilayer rhombic ice structures were formed with an in-plane lattice spacing of 0.31 nm. In this work, a systematic exploration of rhombic ice formation within HNS has been delineated using high-resolution transmission electron microscopy, and its ultrathin morphology was examined using atomic force microscopy. Scanning electron microscopy images revealed high porosity while mechanical testing presented young's modulus of 155 kPa with ∼84% deformation, whereas contact angle suggested high hydrophilicity. The combinations of nanosheets, porosity, nanoconfinement, hydrophilicity, and mechanical strength, motivated us to explore their application as a scaffold for cartilage regeneration, by inducing chondrogenesis of human Wharton Jelly derived mesenchymal stem cells. HNS promoted the formation of cell aggregates giving higher number of spheroid formation and a marked expression of chondrogenic markers (ColI, ColII, ColX, ACAN and S-100), thereby providing some cues for guiding chondrogenic differentiation.

An open-source OpenSim® ankle-foot musculoskeletal model for assessment of strains and forces in dense connective tissues.

BACKGROUND: The ankle and foot are among the most critical load-bearing joints in the human anatomy. Anatomically accurate human body models are imperative to understanding the mechanics of injury and musculoskeletal disorders. A typical human ankle-foot anatomy consists of 25 DOFs, 112 dense connective tissues (DCTs) (92 ligaments, one capsule and 19 fasciae), 30 tendons, and 65 muscles. Existing models possess less than half of the DOFs and physiological elements. In this work, we have developed an ankle-foot joint complex musculoskeletal model for the OpenSim® platform by incorporating 24 degrees of freedom (DOF) comprising of 66 DCTs (46 ligaments, one 1 capsule and 19 fasciae), 30 tendons, and 65 muscles. METHODS: Computed tomography (CT) data of human ankle joint-foot complex was segmented using Mimics ® (Version 17.0, Materialise, Belgium) to obtain models of the cartilages and bones of the ankle joint-foot complex. The position and resting lengths of the DCTs were attained from the MRI data and literature. Five joints, namely, tibiotalar, subtalar, chopart, tarsometatarsal (TMT), and metatarsophalangeal (MTP) joints and their joint axes were formulated to yield 24 DOFs. A forward simulation was carried out at each joint of the ankle-foot complex within their respective range of motions. The strains, instantaneous strain rates, and forces developed in the ligaments during the simulation were studied. RESULTS: During plantar-dorsiflexion of the tibiotalar joint, the anterior tibio-talar ligament (aTTL) yielded the maximum strain compared to all other ligaments. Anterior tibio-fibular ligament (aTFL) experienced extreme strain during subtalar inversion. Hence, the coupled kinematics of subtalar inversion and plantar flexion are failure-prone activities for aTFL. The chopart, TMT, and MTP joints yielded maximum strains or forces for several bundles at the extremes of the range of motion. This signifies that rotations of these joints to their extreme range of motion are prone to failure for the bundles attached to the joint complex. CONCLUSION: The results illustrate the potential application of the proposed OpenSim® ankle-foot model in understanding the ligament injury mechanism during sports activity and its prevention. Researchers can use the proposed model or customise it to study complex kinematics, understanding injury mechanisms, testing fixtures, orthosis or prosthesis, and many more in the domain of musculoskeletal research.

A novel, minimally invasive implant to assist in repeated intraocular drug delivery.

The standard of care for posterior segment disorders such as wet age-related macular degeneration, diabetic macular oedema and retinal vascular occlusions is pharmacotherapy by intravitreal drug delivery. Since the therapeutic effect of these drugs lasts only around 4 to 8 weeks, repeated intravitreal injections are required. Pain is experienced by the patients during injection as the needle courses through the sclera and choroid. The current work describes the design and development of a novel anodized titanium alloy implant that allows for intravitreal injections through the implant so that the needle transverses only the conjunctiva, thus minimizing discomfort to the patient. Both ex-vivo testing of the implant in enucleated goat's eye as well as in-vivo validation in rabbit eyes was carried out. The implant was placed through pars plana via a minor surgical procedure and was sutured to the sclera and covered with conjunctiva. Subsequent intravitreal injections were administered under topical anaesthesia with a 30-gauge needle through the implant thus delivering the drug into the vitreous cavity. Repeated intravitreal injections were administered every 2 weeks via the implant for 3 months in 4 rabbits. Apart from cataract in 1 rabbit, no complications were observed. There was no evidence of intra-ocular inflammation or infection at final follow-up. Histopathological analysis did not reveal any inflammation or necrosis around the area of implant. The implants were subsequently removed at 5 months and scleral wound was closed with a single suture. The sclera and overlying conjunctiva healed well and no intraocular complications were observed after removal.

Cellular studies and sustained drug delivery via nanostructures fabricated on 3D printed porous Neovius lattices of Ti6Al4V ELI.

Site-specific drug delivery has the potential to reduce drug dosage by 3- to 5-folds. Given the propensity of drugs used in the treatment of tuberculosis and cancers, the increased drug dosages via oral ingestion for several months to a few years of medication is often detrimental to the health of patients. In this study, the sustained delivery of drugs with multiscale structured novel Neovius lattices was achieved. 3D Neovius open cell lattices (NOCL) with porosities of 40%, 45%, and 50% were fabricated layer-by-layer on the laser bed fusion process. Micron-sized Ti6Al4V ELI powder was used for 3D printing. The Young's modulus achieved from the novel Neovius lattices were in the range of 1.2-1.6 GPa, which is comparable to human cortical bone and helps to improve implant failure due to the stress shielding effect. To provide sustained drug delivery, nanotubes (NTs) were fabricated on NOCLs via high-voltage anodization. The osteogenic agent icariin was loaded onto the NOCL-NT samples and their release profiles were studied for 7 d. A significantly steady and slow release rate of 0.05% per hour of the drug was achieved using NOCL-NT. In addition, the initial burst release of NOCL-NT was 4 fold lower than that of the open-cell lattices without NTs. Cellular studies using MG63 human osteoblast-like cells were performed to determine their biocompatibility and osteogenesis which were analyzed using Calcein AM staining and Alamar Blue after 1, 5, and 7 d. 3D printed NOCL samples with NTs and with Icariin loaded NTs demonstrated a significant increase in cell proliferation as compared to as printed NOCL samples.

Protein Patterning on Microtextured Polymeric Nanobrush Templates Obtained by Nanosecond Fiber Laser.

Micropatterned polymer brushes have attracted attention in several biomedical areas, i.e., tissue engineering, protein microarray, biosensors, etc., for precise arrangement of biomolecules. Herein, a facile and scalable approach is reported to create microtextured polymer brushes with the ability to generate different type of protein patterns. Nanosecond fiber laser is exploited to generate micropatterns on poly(poly(ethylene glycol) methacrylate) (polyPEGMA) brush modified Ti alloy substrate. Surface initiated atom transfer radical polymerization is employed to grow PolyPEGMA brush (11-87 nm thick) on Ti alloy surface immobilized with initiator having an initiator density (σ*) of 1.5 initiators per nm2 . Polymer brushes are then selectively laser ablated and their presence on nontextured area is confirmed by atomic force microscopy, fluorescence microscopy, and X-ray photoelectron spectroscopy. Spatial orientation of biomolecules is first achieved by nonspecific protein adsorption on areas ablated by the laser, via physisorption. Further, patterned brushes of polyPEGMA are modified to activated ester that gives rise to protein conjugation specifically on nonlaser ablated brush areas. Moreover, the laser ablated brush modified patterned template is also successfully utilized for generating alternate patterns of bacteria. This promising technique can be further extended to create interesting patterns of several biomolecules which are of great interest to biomedical research community.

A cadaveric study on the rate of strain-dependent behaviour of human anterior cruciate ligament.

PURPOSE: Failure of anterior cruciate ligament often occurs in young sports personnel hampering their career. Such ACL ruptures are quite prevalent in sports such as soccer during dynamic loading which occurs at more than one rate of loading. In this work, a structural constitutive equation has been used to predict the forces acting on ACL for different rates of loading. METHODS: Ligaments with distal femur and proximal tibia were subjected to tensile loading to avoid crushing of tissue ends and slipping at higher rates of strain. Custom designed cylindrical grippers were fabricated to clamp the distal femur and proximal tibial bony sections. To estimate parameters for the model, eighteen fresh cadaveric femur-ACL-tibia complex (FATC) samples were experimented on by pure tensile loading at three orders of rates of strain viz., 0.003, 0.03, and 0.3 s^-1. The experimental force-elongation data was used to obtain parameters for De-Vita and Slaughter's equation. The model was validated with additional tensile experiments. RESULTS: Statistical analysis demonstrated failure stress, Young's modulus and volumetric strain energy to vary significantly as a function of rate of strain. Midsection failure was observed only in samples tested at 0.03 s^-1. Femoral or tibial insertion failure were observed in all other experiments irrespective of rate of strain. CONCLUSION: Human FATC samples were tensile tested to failure at three rates of strain using custom-designed cylindrical grippers. A structural model was used to model the data for the ACL behaviour in the linear region of loading to predict ligament behaviour during dynamic activities in live subjects.

Estimation of forces on anterior cruciate ligament in dynamic activities.

In this work, a nonlinear strain rate dependent plugin developed for the OpenSim® platform was used to estimate the instantaneous strain rate (ISR) and the forces on the ACL's anteromedial (aACL) and posterolateral (pACL) bundles during walking and sudden change of direction of running termed as 'plant-and-cut' (PC). The authors obtained the kinematics data for walking via optical motion capture. PC movements, along with running kinematics, were obtained from the literature. A nonlinear plugin developed for ligaments was interfaced with OpenSim® platform to simulate walking and PC motions with a flexed knee and an extended knee. PC phase is sandwiched between an approach phase and take-off phase and was studied at various event velocities (1.8, 3, and 4.2 m s-1), and angles of PC (23°, 34°, and 45°) as encountered in adult ball games. In both cases of PC-with-extended knee and PC-with-flexed-knee, the maximum forces on both the ACL bundles were observed after the take-off phase. A maximum force of ~ 35 N kg-1 of body weight (BW) was observed on aACL after the take-off phase for an event velocity of 4.2 m s-1. In the posterolateral bundle (pACL), the maximum forces (~ 40 N kg-1 of BW) were observed towards the end of the mid-swing phase (after the take-off phase) for the various combinations of the parameters studied. The forces observed in the simulation of PC-with-flexed-knee and PC-with-extended-knee has resulted in magnitude higher than sustainable by the adults. This study is novel in attempting to incorporate differing rates-of-strain that have been shown to alter soft tissue properties into the OpenSim® musculoskeletal model. The proposed model can be used by researchers to predict the forces during various kinematic activities for other soft tissues.

Epoxy based sandwich composite using three-dimensional integrally woven fabric as core strengthened with additional carbon face-sheets.

Sandwich composites are three-dimensional (3D) composite structures that offer higher stiffness with overall low density. However, they suffer from low strength; thus, not suited for load bearing applications. In this work, an attempt is made to develop a high strength lightweight sandwich composite suited for load-bearing applications. A sandwich composite based on 3D integrally woven fabric with thickness 3 mm as the core and strengthened with additional 2x2 twill woven carbon fabric face-sheets is reported. The samples were manufactured by wet hand lay co-lamination process using Araldite® LY 1564 epoxy as the matrix polymer and with fiber fraction of 50% by weight. The number of additional carbon face-sheets over the core was varied from two to eight in steps of two. The composite samples were experimented under three-point bending and edgewise compression tests to determine the flexural and compressive strengths in both warp and weft directions. The weft direction samples yielded higher flexural and compressive strengths due to the continuous arrangement of the core pile yarn. The samples with six carbon face-sheets tested along the weft direction offered the highest specific strengths of ~409 kN m/kg and 259 kN m/kg in bending and compression tests. Similarly, the flexural strength was ~340 MPa, and compressive strength was ~217 MPa. A detailed fractography study revealed no core crushing or compression failure of the core during bending tests.

Functionalized Co2FeAl Nanoparticles for Detection of SARS CoV-2 Based on Reverse Transcriptase Loop-Mediated Isothermal Amplification.

Loop-mediated isothermal amplification (LAMP) is a sensitive, efficient, and rapid nucleic acid amplification technique resulting in a large number of amplicons; however, it suffers from a high incidence of false positives due to carry-over and aerosol. Herein, we report a 10 min nano-capture system that is used in conjunction with a modified reverse transcriptase-LAMP (RT-LAMP) assay for the accurate detection of SARS CoV-2 virus. The nano-capture system employs in-house-designed probe-functionalized magnetic nanoparticles Co2FeAl (cobalt-based Heusler alloy) for efficient capture of contaminating amplicons from the reaction mixture preceding RT-LAMP. The nano-cleaned RT-LAMP assay along with engineered primers successfully detected the presence of 10 copies of SARS CoV-2 virus while completely eliminating the incidence of false positives. The presented contaminant-capture method has been compared with other approaches for elimination of contaminants and was found to be more effective. The insight brought in this work is the design of a rapid nano-capture system that hybridizes with contaminating amplicons (carry-over) with high specificity to enable easy removal from the assay for elimination of false positives. The method has been proven to be successful for RT-LAMP assays in the rapid and highly specific detection of SARS CoV-2, which is currently a major challenge for global health. To the best of our knowledge, this is the first work involving a nano-based cleaning strategy for reliable and rapid diagnosis using isothermal amplification approaches.

Levels of TGF-ß1 in peri-miniscrew implant crevicular fluid.

The peri-miniscrew implant crevicular fluid is analogous to gingival crevicular fluid, and its contents reflect the state of inflammation and health during the life of the miniscrews in the mouth. The stability of MSI is fundamental to its role as an anchorage. This study aimed to evaluate transforming growth factor-beta one (TGF-ß1) of the peri-miniscrew implant crevicular fluid (PMICF), on implant insertion, pre- and post-loading of MSIs to find a clue to their role in the stability of MSI. Fifty-two MSIs sites were placed in the mouths of 13 patients aged 12-26 years undergoing orthodontic treatment. PMICF was collected using micro-pipettes at T1 (day 0, 1 h after MSI implantation), T2 (day 1), T3/baseline (day 21, preloading of MSI), T4 (day 21, 1 h post loading), T5 (day 22, 1 day post loading), T6 (day 43, 3 weeks post loading). The levels of TGF-ß1 were estimated by enzyme-linked immunosorbent assay (ELISA). The data were subjected to statistical analysis. Of the 52 MSIs, 20 MSIs failed at T3. In the case of successful MSIs, the TGF-ß1 levels were found to monotonously decrease from T1 (~1400 pg/mL) until T3 (~700 pg/mL) and saturate thereafter. In the case of failed MSIs, the levels of TGF-ß1 at various time periods were approximately constant and of much lower value than corresponding time periods of successful MSIs. This study highlights the role of TGF- ß1 in bone metabolism around miniscrew reflecting the state of inflammation from 1 h post-implantation.

Simultaneous and high sensitive detection of Salmonella typhi and Salmonella paratyphi a in human clinical blood samples using an affordable and portable device.

Enteric fever is one of the leading causes of infection and subsequent fatality (greater than 1.8 million) (WHO 2018), especially in the developing countries due to contaminated water and food inter twinned with unhygienic practices. Clinical gold standard technique of culture-based method followed by biochemical tests demand 72+ hours for diagnosis while newly developed techniques (like PCR, RT-PCR, DNA microarray etc.) suffer from high limit of detection or involve high-cost infrastructure or both. In this work, a quick and highly specific method, SMOL was established for simultaneous detection of Salmonella paratyphi A and Salmonella typhi in clinical blood samples. SMOL consists of (i) pre-concentration of S. typhi and S. paratyphi A cells using magnetic nanoparticles followed by (ii) cell lysis and DNA extraction (iii) amplification of select nucleic acids by LAMP technique and (iv) detection of amplified nucleic acids using an affordable portable device (costs less than $70). To identify the viability of target cells at lower concentrations, the samples were processed at two different time periods of t = 0 and t = 4 h. Primers specific for the SPA2539 gene in S. paratyphi A and STY2879 gene in S. typhi were used for LAMP. Within 6 h SMOL was able to detect positive and negative samples from 55 human clinical blood culture samples and detect the viability of the cells. The results were concordant with culture and biochemical tests as well as by qPCR. Statistical power analysis yielded 100%. SMOL results were concordant with culture and biochemical tests as well as by qPCR. The sensitive and affordable system SMOL will be effective for poor resource settings.

Graphene Quantum Dots in the Game of Directing Polymer Self-Assembly to Exotic Kagome Lattice and Janus Nanostructures.

Graphene quantum dots (GQDs) are the harbingers of a paradigm shift that revitalize self-assembly of the colloidal puzzle by adding shape and size to the material-design palette. Although self-assembly is ubiquitous in nature, the extent to which these molecular legos can be engineered reminds us that we are still apprenticing polymer carpenters. In this quest to unlock exotic nanostructures ascending from eventual anisotropy, we have utilized different concentrations of GQDs as a filler in free-radical-mediated aqueous copolymerization. Extensive polymer grafting over the geometrically confined landscape of GQDs (0.05%) bolsters crystallization instilling a loom which steers interaction of polymeric cilia into interlaced equilateral triangles with high sophistication. Such two-dimensional (2D) assemblies epitomizing the planar tiling of "Star of David" forming a molecular kagome lattice (KL) without metal templation evoke petrichor. Interestingly, a higher percentage (0.3%) of GQDs allow selective tuning of the interfacial property of copolymers breaking symmetry due to surface energy incongruity, producing exotic Janus nanomicelles (JNMs). Herein, with the help of a suite of characterizations, we delineate the mechanism behind the formation of the KL and JNMs which forms a depot of heightened drug accretion with targeted delivery of 5-fluorouracil in the colon as validated by gamma scintigraphy studies.

An open-source plugin for OpenSim® to model the non-linear behaviour of dense connective tissues of the human knee at variable strain rates.

The force-length characteristics of dense connective tissues (DCTs) vary non-linearly as a function of strain rate. However, there is no class of OpenSim® available to incorporate the effect of strain rate into the OpenSim® model. In this work, a new plugin for OpenSim® was developed to incorporate the non-linear strain rate behaviour of dense connective tissues (DCTs) of the human knee. Experimental force-length plots from the literature were used to extract the shape factor, scale factor, the coefficient of viscosity and elastic stiffness corresponding to specific strain rates. A new class object termed as NonLinearLigament was formulated using a customized plugin based on a structural constitutive model. A test platform was created to evaluate the force-length patterns at multiple strain rates ranging from 0.0001 s-1 to 100 s-1 for the DCT bundles. Knee kinematics of 25 DCT bundles were subjected to forward simulation at various strain rates. To understand the significance, the force-length characteristics of each of the DCTs were simulated as a function of strain rate for both existing Ligament class of OpenSim® and the proposed NonLinearLigament class. In the proposed ligament class, higher forces were observed with an increase of strain rate in DCTs. Existing Ligament class in OpenSim® was devoid of any changes at different strain rates. In summary, the developed plugin takes into account the short term viscoelastic behaviour of DCTs and hence, would help in accurate modelling of tissue behaviour specifically for dynamic situations.

Relationship between Dislocation Density and Antibacterial Activity of Cryo-Rolled and Cold-Rolled Copper.

In the present work, cold rolling and cryo-rolling were performed on 99% commercially pure copper substrates. Both cold and cryo-rolling processes caused severe plastic deformation that led to an increase in dislocation density by 14× and 28× respectively, as compared to the pristine material. Increases in average tensile strengths, by 75% (488 MPa) and 150% (698 MPa), were observed in the two rolled materials as the result of the enhancement in dislocation density. In addition to strength, enhanced antibacterial property of cryo-rolled copper was observed in comparison to cold rolled and pristine copper. Initial adhesion and subsequent proliferation of bio-film forming Gram-positive bacteria Staphylococcus aureus was reduced by 66% and 100% respectively for cryo-rolled copper. Approximately 55% protein leakage, as well as ethidium bromide (EtBr) uptake, were observed confirming rupture of cell membrane of S. aureus. Inductively coupled plasma-mass spectroscopy reveals higher leaching of elemental copper in nutrient broth media from the cryo-rolled copper. Detailed investigations showed that increased dislocation led to leaching of copper ions that caused damage to the bacterial cell wall and consequently killing of bacterial cells. Cryo-rolling enhanced both strength, as well as antibacterial activity, due to the presence of dislocations.

Outcome and safety analysis of 3D-printed patient-specific pedicle screw jigs for complex spinal deformities: a comparative study.

BACKGROUND CONTEXT: Spinal deformities are very challenging to treat and have a great risk of neurologic complications because of hardware placement during corrective surgery. Various techniques have been introduced to ensure safe and accurate placement of pedicle screws. Patient-specific screw guides with predrawn and prevalidated trajectory seem to be an attractive option. PURPOSE: We have focused on developing three-dimensional (3D) printing technique for complex spinal deformities in India. This study also aimed to compare the placement of pedicle screw with 3D printing and freehand technique. STUDY DESIGN/SETTINGS: This is a retrospective comparative clinical study in an academic institutional setting. PATIENT SAMPLE: A total of 20 patients were enrolled during the study: 10 were operated on with the help of 3D printing (Group 1) and 10 were operated on with freehand technique (Group 2). Group 1 included six patients with congenital scoliosis, three patients with adolescent idiopathic scoliosis (AIS), and one patient with post-tubercular kyphosis, and Group 2 included five patients with congenital scoliosis, four patients with AIS, and one patient with post-tubercular kyphosis. OUTCOME MEASURES: Primary outcomes were measured in terms of screw violation, and secondary outcomes were measured in terms of surgical time, blood loss, radiation exposure (number of shoots required), and complications. MATERIALS AND METHODS: MIMICS Base v18.0 software was used for 3D reconstruction from computed tomography scan images of all the patients. 3-Matic software was used to create a drill guide. A 3D printer from Stratasys Mojo with ABS P430 model material cartilage (a thermoplastic material) was used for the printing of the vertebra model and jigs. A two-sample test of proportion was used to compare correctly and wrongly placed pedicle screws with 3D printing and freehand technique. t Test with equal variance was used for operating surgical time and blood loss. RESULTS: No superior or inferior screw violation was observed in any of our patients in either group. We found a significant difference (p=.03) between the two groups regarding perfect screw placement in favor of 3D printing. There were 13 Grade 2 medial perforations in the freehand group and 3 in the 3D printing group. There was no Grade 3 medial perforation in either group. Six Grade 2 lateral perforations in the freehand group and seven in the 3D printing group were observed. Three Grade 3 lateral perforations in the freehand group and two in 3D printing group were observed. Analysis showed a statistically significant (p=.005) medial violation in the freehand group. Surgical time was significantly less (p=.03) in the 3D printing group compared with the freehand group. Mean blood loss was higher in the freehand group but was not statistically significant (p=.3) in the 3D printing group. Fluoroscopic shots required were less in number in the 3D printing group compared with the freehand group. There was no neurologic deficit in any of the patients in the two groups. CONCLUSIONS: In our study, focusing on spinal deformities with statistically significant higher rates of accurate screw positioning and higher numbers of inserted screws with 3D printing was possible because of enhanced safety, particularly at apical levels. As such, spinal deformities are difficult to treat worldwide. In India, these deformities are often neglected and present at a very late and a much more deformed state when their treatment becomes even more challenging. Developing these patient-specific drill templates will enable an average spine surgeon to treat these patients with much ease and safety.