Bubble-Based Microrobots with Rapid Circular Motions for Epithelial Pinning and Drug Delivery

Remotely powered microrobots are proposed as next-generation vehicles for drug delivery. However, most microrobots swim with linear trajectories and lack the capacity to robustly adhere to soft tissues. This limits their ability to navigate complex biological environments and sustainably release drugs at target sites. In this work, bubble-based microrobots with complex geometries are shown to efficiently swim with non-linear trajectories in a mouse bladder, robustly pin to the epithelium, and slowly release therapeutic drugs. The asymmetric fins on the exterior bodies of the microrobots induce a rapid rotational component to their swimming motions of up to ≈150 body lengths per second. Due to their fast speeds and sharp fins, the microrobots can mechanically pin themselves to the bladder epithelium and endure shear stresses commensurate with urination. Dexamethasone, a small molecule drug used for inflammatory diseases, is encapsulated within the polymeric bodies of the microrobots. The sustained release of the drug is shown to temper inflammation in a manner that surpasses the performance of free drug controls. This system provides a potential strategy to use microrobots to efficiently navigate large volumes, pin at soft tissue boundaries, and release drugs over several days for a range of diseases.     

Biohybrid Design Gets Personal: New Materials for Patient-Specific Therapy

Precision medicine requires materials and devices that can sense and adapt to dynamic physiological and pathological conditions. This motivates the design and manufacture of biohybrid materials that mimic the responsive behaviors demonstrated by natural biological systems. Two parallel approaches to biohybrid design are presented—biomimetics and biointegration. Biohybrid hydrogels that mimic the form and function of natural materials, or that integrate living cells or bioactive moieties, can respond to a range of environmental stimuli in parallel, including heat, light, pH, hydration, enzymes, and electric, mechanical, and magnetic forces. A range of examples that illustrate the tremendous potential of this nascent discipline are presented, and ongoing technical challenges related to manufacturing, storage, transport, and external noninvasive control of these materials that will need to be overcome in the coming years are outlined. The ethical, educational, and regulatory challenges that will govern translation of biohybrid design into medical applications are also discussed. Personalized medical therapies that target the precise needs of patients are a critically needed and expanding market. Biohybrid design offers the unique ability to manufacture materials and devices that match the dynamic and patient-specific in vivo environment, promising to generate more effective and safe therapies that enable personalized care.     

Synthesis and characterization of novel ion-exchange resin based on polyimide containing 8-hydroxyquinoline as a pendent groups

Novel ion-exchange resin (PBMDDMCMHQ polyimide) having 8-hydroxyuinoline as a pendent groups was prepared using phenylenebismaleimide-diamine polyimide (PBMDDM) and 5-chloromethyl-8-hydroxyquinoline hydrochloride (CMHQ). Phenylenebismaleimide-diamine polyimide (PBMDDM) was prepared by Michael addition reaction of 1,3-phenylenebismaleimide (PBM) and 4,4’-diaminodiphenyl methane (DDM). The resulting ion-exchange resin was characterized by spectral techniques. Polymeric metal chelates of ion-exchange resin were also prepared using transition metal ions Zn(II), Cu(II), Ni(II), Co(II) and Mn(II), and were duly characterized. Ion-exchange properties of ion-exchange resin (PBMDDMCMHQ) for Fe(III), Zn(II), Ni(II) and Cu(II) metal ions were also studied by batch-equilibration method. The produced ion-exchange resin (PBMDDMCMHQ) has thermal stability up to 220°C and can be used over a wide pH range. It has good metal up take capacity at varying pH range and can be recycled.     

Optimal replacement policy for a repairable system with multiple vacations and imperfect fault coverage

The present investigation deals with the reliability analysis of a repairable system consisting of single repairman who can take multiple vacations. The system failure may occur due to two types of faults termed as major and minor. When the system has failed due to minor faults, it is perfectly recovered by the repairman. If the system failure is due to major faults, there are some recovery levels/procedures that recover the faults imperfectly with some probability. However, the system cannot be repaired in ‘as good as new’ condition. It is assumed that the repairman can perform some other tasks when either the system is idle or waiting for recovery from the faults. The life time of the system and vacation time of the repairman are assumed to be exponential distributed while the repair time follows the general distribution. By assuming the geometric process for the system working/vacation time, the supplementary variable technique and Laplace transforms approach are employed to derive the reliability indices of the system. We propose the replacement policy to maximize the expected profit after a long run time. The validity of the analytical results is justified by taking numerical illustrations.     

提高DC-DC变换器效率用高单元密度屏蔽栅功率MOSFET

本文介绍了飞兆半导体公司最新开发的高单元密度、屏蔽栅功率MOSFET的结构。这种屏蔽栅结构有助于建立电荷平衡,从而减少MOSFET的通态电阻和栅电荷。这种新技术能使通态电阻比前一代减少50%以上。为进一步改善器件特性,一种肖特基器件也被单片集成在这种新型MOSFET中,使得反向恢复电荷减少了将近20%。上述措施直接减小了在高频、大电流和高输入电压下非常关键的体二极管损耗。该新型器件在典型的同步降压变换器应用中,能提供1.5%的最高效率改进。     

Suspended Wash Load Transport of Nonuniform Sediments

The results of an experimental study on transport of suspended wash load through a coarse-bed stream are presented. The experiments were conducted under different concentrations of fine suspended sediment (wash load of uniform size, 0.064 mm diameter) and with three different coarse-bed sediments: two having uniform sizes and one with nonuniform size distribution. For any equilibrium concentration of wash load in suspension, a definite proportion of the wash material was observed to be present within the bed material. No difference is found in this regard between wash load and suspended load transport. Therefore, the relationship, as stated by Samaga et al., for the parameter representing sheltering—exposure and interference effects in the suspended load transport of nonuniform sediments was applied in a modified form by using the present data and the data collected from the literature.     

CD73 and PD-L1 as Potential Therapeutic Targets in Gallbladder Cancer

Gallbladder cancer (GBC) is one of the most common and aggressive biliary tract cancers with a dismal prognosis. Ongoing clinical trials are evaluating a few selected immune checkpoint inhibitors (ICIs) as monotherapy for the treatment of GBC patients. However, only a subset of patients benefits from these treatments. To improve ICI therapy response, molecular mechanisms that confer resistance to immune checkpoint (IC) blockade needs to be explored. Epithelial-to-mesenchymal transition (EMT) program and cancer stem cells (CSCs) have been implicated as key processes that confer ICI treatment resistance. However, in GBC the EMT-CSC-IC axis has not yet been clearly elucidated. This study aims to examine the aberrant expression of ICs associated with CSC and EMT. We successfully enriched CSCs by utilizing a 3-dimensional culture system and established a reversible EMT model with human GBC NOZ cell line. Notably, ICs CD73 and PD-L1 were closely associated with both CSC and EMT phenotypes. Knockdown of CD73 or PD-L1 reduced the proliferative and motile abilities of both adherent monolayers and anchorage-free spheroids. In conclusion, blocking CD73 and PD-L1 offer a promising therapeutic strategy for targeting highly aggressive populations with CSC and EMT phenotype to improve GBC patient prognosis.     

Carboxymethylation of cellulosic material (average degree of polymerization 2600) isolated from cotton (Gossypium) linters with respect to degree of substitution and rheological behavior

Carboxymethylation of cellulosic material (average degree of polymerization 2600) containing 76.5% cellulose and 23.6% xylose isolated from cotton (Gossypium) linters was studied under varying reaction conditions with respect to maximum degree of substitution (DS). The influence of reaction conditions on the apparent viscosity of the prepared derivatives was also studied. The conditions optimized were sodium hydroxide concentration 3.75M, monochloroacetic acid concentration 2.05 mol/AGU, carboxymethylation time 3.5 h, and temperature 55°C, to yield carboxymethyl cellulose of DS 0.77. Rheological studies of 1 and 2% solutions of the optimized product revealed their non‐Newtonian pseudoplastic behavior. Repeating units of the optimized product were also determined by HPLC after complete depolymerization of the polymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1477–1482, 2005     

120 keV Ar ion-induced red and blue shift of SPR Wavelength of Au nanoparticles in fullerene C60

Journal of Materials Science: Materials in Electronics - Au nanoparticles are synthesized in a fullerene C60 matrix using the thermal co-evaporation technique. Fullerene C60 is chosen due to its...