Engineered Nanoporous Frameworks for Adsorption Cooling Applications

The energy demand for traditional vapor-compressed technology for space cooling continues to soar year after year due to global warming and the increasing human population's need to improve living and working conditions. Thus, there is a growing demand for eco-friendly technologies that use sustainable or waste energy resources. This review discusses the properties of various refrigerants used for adsorption cooling applications followed by a brief discussion on the thermodynamic cycle. Next, sorbents traditionally used for cooling are reviewed to emphasize the need for advanced capture materials with superior properties to improve refrigerant sorption. The remainder of the review focus on studies using engineered nanoporous frameworks (ENFs) with various refrigerants for adsorption cooling applications. The effects of the various factors that play a role in ENF-refrigerant pair selection, including pore structure/dimension/shape, morphology, open-metal sites, pore chemistry and possible presence of defects, are reviewed. Next, in-depth insights into the sorbent-refrigerant interaction, and pore filling mechanism gained through a combination of characterization techniques and computational modeling are discussed. Finally, we outline the challenges and opportunities related to using ENFs for adsorption cooling applications and provide our views on the future of this technology.

Molecular-level insight into the chlorofluorocarbons adsorption by defective covalent organic polymers

Halocarbons have important industrial applications, however they contribute to global warming and the fact that they can cause ozone depletion. Hence, the techniques that can capture and recover the used halocarbons with energy efficiency methods have recently received greater attention. In this contribution, we report the capture of dichlorodifluoromethane (R12), which has high global warming and ozone depletion potential, using covalent organic polymers (COPs). The defect-engineered COPs were synthesized and demonstrated outstanding sorption capacities, ~226 wt% of R12 combined with linear-shaped adsorption isotherms. We further identified the plausible microscopic adsorption mechanism of the investigated COPs via grand canonical Monte Carlo simulations applied to non-defective and a collection of atomistic models of the defective COPs. The modeling work suggests that significant R12 adsorption is attributed to a gradual increment of porosities due to isolated/interconnected micro-/meso-pore channels and the change of the long-range ordering of both COPs. The successive hierarchical-pore-filling mechanism promotes R12 molecular adsorption via moderate van der Waals adsorbate-adsorbent interactions in the micropores of both COPs at low pressure followed by adsorbate-adsorbate interactions in the extra-voids created at moderate to high pressure ranges. This continuous pore-filling mechanism makes defective COPs as promising sorbents for halocarbon adsorption.

A Microporous Multi-Cage Metal-Organic Framework for an Effective One-Step Separation of Branched Alkanes Feeds

The improvement of the Total Isomerization Process (TIP) for the production of high-quality gasoline with the ultimate goal of reaching a Research Octane Number (RON) higher than 92 requires the use of specific sorbents to separate pentane and hexane isomers into classes of linear, mono- and di-branched isomers. Herein we report the design of a new multi-cage microporous Fe(III)-MOF (referred to as MIP-214, MIP stands for materials of the Institute of Porous Materials of Paris) with a flu-e topology, incorporating an asymmetric heterofunctional ditopic ligand, 4-pyrazolecarboxylic acid, that exhibits an appropriate microporous structure for a thermodynamic-controlled separation of hydrocarbon isomers. This MOF produced via a direct, scalable, and mild synthesis route was proven to encompass a unique separation of C5/C6 isomers by classes of low RON over high RON alkanes with a sorption hierarchy: (n-hexane≫n-pentane≈2-methylpentane>3-methylpentane)low RON≫(2,3-dimethylbutane≈i-pentane≈2,2-dimethylbutane)high RON following the adsorption enthalpy sequence. We reveal for the first time that a single sorbent can efficiently separate such a complex mixture of high RON di-branched hexane and mono-branched pentane isomers from their low RON counterparts, which is a major achievement reported so far.

When Polymorphism in Metal-Organic Frameworks Enables Water Sorption Profile Tunability for Enhancing Heat Allocation and Water Harvesting Performance

The development of thermally driven water-sorption-based technologies relies on high-performing water vapor adsorbents. Here, polymorphism in Al-metal-organic frameworks is disclosed as a new strategy to tune the hydrophilicity of MOFs. This involves the formation of MOFs built from chains of either trans- or cis- µ-OH-connected corner-sharing AlO4(OH)2 octahedra. Specifically, [Al(OH)(muc)] or MIP-211, is made of trans, trans-muconate linkers, and cis-µ-OH-connected corner-sharing AlO4(OH)2 octahedra giving a 3D network with sinusoidal channels. The polymorph MIL-53-muc has a tiny change in the chain structure that results in a shift of the step position of the water isotherm from P/P0 ≈ 0.5 in MIL-53-muc, to P/P0 ≈ 0.3 in MIP-211. Solid-state NMR and Grand Canonical Monte Carlo reveal that the adsorption occurs initially between two hydroxyl groups of the chains, favored by the cis-positioning in MIP-211, resulting in a more hydrophilic behavior. Finally, theoretical evaluations show that MIP-211 would allow achieving a coefficient of performance for cooling (COPc) of 0.63 with an ultralow driving temperature of 60 °C, outperforming benchmark sorbents for small temperature lifts. Combined with its high stability, easy regeneration, huge water uptake capacity, green synthesis, MIP-211 is among the best adsorbents for adsorption-driven air conditioning and water harvesting from the air.

Confined Water Cluster Formation in Water Harvesting by Metal-Organic Frameworks: CAU-10-H versus CAU-10-CH3

Several metal-organic frameworks (MOFs) excel in harvesting water from the air or as heat pumps as they show a steep increase in water uptake at 10-30 % relative humidity (RH%). A precise understanding of which structural characteristics govern such behavior is lacking. Herein, CAU-10-H and CAU-10-CH3 are studied with H, CH3 corresponding to the functions grafted to the organic linker. CAU-10-H shows a steep water uptake ≈18 RH% of interest for water harvesting, yet the subtle replacement of H by CH3 in the organic linker drastically changes the water adsorption behavior to less steep water uptake at much higher humidity values. The materials' structural deformation and water ordering during adsorption with in situ sum-frequency generation, in situ X-ray diffraction, and molecular simulations are unraveled. In CAU-10-H, an energetically favorable water cluster is formed in the hydrophobic pore, tethered via H-bonds to the framework μOH groups, while for CAU-10-CH3, such a favorable cluster cannot form. By relating the findings to the features of water adsorption isotherms of a series of MOFs, it is concluded that favorable water adsorption occurs when sites of intermediate hydrophilicity are present in a hydrophobic structure, and the formation of energetically favorable water clusters is possible.

Chiral Reticular Chemistry: A Tailored Approach Crafting Highly Porous and Hydrolytically Robust Metal-Organic Frameworks for Intelligent Humidity Control

Control of humidity within confined spaces is critical for maintaining air quality and human well-being, with implications for environments ranging from international space stations and pharmacies to granaries and cultural relic preservation sites. However, existing techniques rely on energy-intensive electrically driven equipment or complex temperature and humidity control (THC) systems, resulting in imprecision and inconvenience. The development of innovative techniques and materials capable of simultaneously meeting the stringent requirements of practical applications holds the key to creating intelligent and energy-efficient humidity control devices. In this study, we introduce chiral reticular chemistry as a tailored synthetic approach, targeting a highly porous hea topological framework characterized by intrinsic interpenetrating pore architecture. This groundbreaking design successfully circumvents the traditional compromise between the pore volume and hydrolytic stability. Our metal-organic framework (MOF) exhibits an extraordinary working capacity, setting a new record at 1.35 g g-1 within the relative humidity (RH) range of 40-60%, without exhibiting hysteresis. Consequently, it emerges as a state-of-the-art candidate for intelligent humidity regulation within confined spaces. Utilizing single-crystal X-ray measurements and molecular simulations, we unequivocally elucidate the mechanism of water clustering and pore filling, underscoring the pivotal role of the linker functionality in governing the water seeding process. Our findings represent a significant advancement in the field, paving the way for the development of highly efficient humidity control technologies and offering promising solutions for diverse real-world scenarios.

Endoscopic Transnasal Repair of Cerebrospinal Fluid Leakage: Experience in BSMMU

Endoscopic transnasal repair of CSF rhinorrhoea is gaining popularity around the world because of its tremendous success rate but it depends on defect site, size, technique of repair, experiences of surgeon and also patient's profile. Aim of this study was to analysis of surgical outcome of endoscopic transnasal repair of CSF rhinorrhoea. A retrospective study carried out in the department of ENT and Head neck surgery at Bangabandhu Sheikh Mujib Medical University (BSMMU) from January 2018 to December 2019. Of the total of 24 patients 16(66.0%) were female and 8(33.0%) males. The commonest site of the leak was in the cribriform plate in 18(75.3%) followed by 5(20.8%) in the fovea ethmoidalis, and 1(4.0%) in the sphenoid sinus, the overall success rate of this series with first surgical procedure was 95.83% and 100.0% with a second procedure. Meticulous pre-operative evaluation, proper identification of leakage site, choice of graft materials and surgical technique are keys to attaining excellent results.

A squarate-pillared titanium oxide quantum sieve towards practical hydrogen isotope separation

Separating deuterium from hydrogen isotope mixtures is of vital importance to develop nuclear energy industry, as well as other isotope-related advanced technologies. As one of the most promising alternatives to conventional techniques for deuterium purification, kinetic quantum sieving using porous materials has shown a great potential to address this challenging objective. From the knowledge gained in this field; it becomes clear that a quantum sieve encompassing a wide range of practical features in addition to its separation performance is highly demanded to approach the industrial level. Here, the rational design of an ultra-microporous squarate pillared titanium oxide hybrid framework has been achieved, of which we report the comprehensive assessment towards practical deuterium separation. The material not only displays a good performance combining high selectivity and volumetric uptake, reversible adsorption-desorption cycles, and facile regeneration in adsorptive sieving of deuterium, but also features a cost-effective green scalable synthesis using chemical feedstock, and a good stability (thermal, chemical, mechanical and radiolytic) under various working conditions. Our findings provide an overall assessment of the material for hydrogen isotope purification and the results represent a step forward towards next generation practical materials for quantum sieving of important gas isotopes.

Porous Salts Containing Cationic Al24-Hydroxide-Acetate Clusters from Scalable, Green and Aqueous Synthesis Routes

The solution chemistry of aluminum is highly complex and various polyoxocations are known. Here we report on the facile synthesis of a cationic Al24 cluster that forms porous salts of composition [Al24(OH)56(CH3COO)12]X4, denoted CAU-55-X, with X = Cl-, Br-, I-, HSO4-. Three-dimensional electron diffraction was employed to determine the crystal structures. Various robust and mild synthesis routes for the chloride salt [Al24(OH)56(CH3COO)12]Cl4 in water were established resulting in high yields (> 95%, 215 g per batch) within minutes. Specific surface areas and H2O capacities with maximum values of up to 930 m2/g and 430 mg/g are observed. The particle size of CAU-55-X can be tuned between 140 nm and 1250 nm, permitting its synthesis as stable dispersions or as highly crystalline powders. The positive surface charge of the particles, allow fast and effective adsorption of anionic dye molecules and adsorption of poly- and perfluoroalkyl substances (PFAS).

Separation of Branched Alkanes Feeds by a Synergistic Action of Zeolite and Metal-Organic Framework

Zeolites and metal-organic frameworks (MOFs) are considered as "competitors" for new separation processes. The production of high-quality gasoline is currently achieved through the total isomerization process that separates pentane and hexane isomers while not reaching the ultimate goal of a research octane number (RON) higher than 92. This work demonstrates how a synergistic action of the zeolite 5A and the MIL-160(Al) MOF leads to a novel adsorptive process for octane upgrading of gasoline through an efficient separation of isomers. This innovative mixed-bed adsorbent strategy encompasses a thermodynamically driven separation of hexane isomers according to the degree of branching by MIL-160(Al) coupled to a steric rejection of linear isomers by the molecular sieve zeolite 5A. Their adsorptive separation ability is further evaluated under real conditions by sorption breakthrough and continuous cyclic experiments with a mixed bed of shaped adsorbents. Remarkably, at the industrially relevant temperature of 423 K, an ideal sorption hierarchy of low RON over high RON alkanes is achieved, i.e., n-hexane ≫ n-pentane ≫ 2-methylpentane > 3-methylpentane ⋙ 2,3-dimethylbutane > isopentane ≈ 2,2-dimethylbutane, together with a productivity of 1.14 mol dm^-3 and a high RON of 92, which is a leap-forward compared with existing processes.

Special Non-Newtonian Third-Grade Fluid Flow with Magnetic Field: A Numerical Study

The Buongiorno model is utilized for the non-Newtonian third-grade fluid. With non-linear radiation and magnetic action, it incorporates both Brownian motion and thermophoresis processes. Aim this research is to look at non-Newtonian third-grade fluid boundary layer flow with non-linear solar energy thermal radiation and the magnetic effect. The similarity transformation is used to convert nonlinear PDEs into ODEs. Then numerically solved by shooting technique and the sixth-order R-K method. For various physical parameters, derived findings are graphically discussed. We believe that the current findings can be utilized to explain the non-Newtonian properties of second and third-grade fluids, as well as for applications in tribology, the automobile industry, and other fields.

Synthesis, Characterization, and Encapsulation Properties of Rigid and Flexible Porphyrin Cages Assembled from N-Heterocyclic Carbene-Metal Bonds

Four porphyrins equipped with imidazolium rings on the para positions of their meso aryl groups were prepared and used as tetrakis(N-heterocyclic carbene) (NHC) precursors for the synthesis of porphyrin cages assembled from eight NHC-M bonds (M = Ag⁺ or Au⁺). The conformation of the obtained porphyrin cages in solution and their encapsulation properties strongly depend on the structure of the spacer -(CH₂)_n- (n = 0 or 1) between meso aryl groups and peripheral NHC ligands. In the absence of methylene groups (n = 0), porphyrin cages are rather rigid and the short porphyrin-porphyrin distance prevents the encapsulation of guest molecules like 1,4-diazabicyclo[2.2.2]octane (DABCO). By contrast, the presence of methylene functions (n = 1) between meso aryl groups and peripheral NHCs offers additional flexibility to the system, allowing the inner space between the two porphyrins to expand enough to encapsulate guest molecules like water molecules or DABCO. The peripheral NHC-wingtip groups also play a significant role in the encapsulation properties of the porphyrin cages.

Porous Covalent Organic Polymers for Efficient Fluorocarbon-Based Adsorption Cooling

Adsorption-based cooling is an energy-efficient renewable-energy technology that can be driven using low-grade industrial waste heat and/or solar heat. Here, we report the first exploration of fluorocarbon adsorption using porous covalent organic polymers (COPs) for this cooling application. High fluorocarbon R134a equilibrium capacities and unique overall linear-shaped isotherms are revealed for the materials, namely COP-2 and COP-3. The key role of mesoporous defects on this unusual adsorption behavior was demonstrated by molecular simulations based on atomistic defect-containing models built for both porous COPs. Analysis of simulated R134a adsorption isotherms for various defect-containing atomistic models of the COPs shows a direct correlation between higher fluorocarbon adsorption capacities and increasing pore volumes induced by defects. Combined with their high porosities, excellent reversibility, fast kinetics, and large operating window, these defect-containing porous COPs are promising for adsorption-based cooling applications.

Metal-Dependent and Selective Crystallization of CAU-10 and MIL-53 Frameworks through Linker Nitration

The reaction of the V-shaped linker molecule 5-hydroxyisophthalic acid (H2 L0 ), with Al or Ga nitrate under almost identical reaction conditions leads to the nitration of the linker and subsequent formation of metal-organic frameworks (MOFs) with CAU-10 or MIL-53 type structure of composition [Al(OH)(L)], denoted as Al-CAU-10-L0, 2, 4, 6 or [Ga(OH)(L)], denoted as Ga-MIL-53-L2 . The Al-MOF contains the original linker L0 as well as three different nitration products (L2 , L4 and L4/6 ), whereas the Ga-MOF mainly incorporates the linker L2 . The compositions were deduced by 1 H NMR spectroscopy and confirmed by Rietveld refinement. In situ and ex situ studies were carried out to follow the nitration and crystallization, as well as the composition of the MOFs. The crystal structures were refined against powder X-ray diffraction (PXRD) data. As anticipated, the use of the V-shaped linker results in the formation of the CAU-10 type structure in the Al-MOF. Unexpectedly, the Ga-MOF crystallizes in a MIL-53 type structure, which is usually observed with linear or slightly bent linker molecules. To study the structure directing effect of the in situ nitrated linker, pure 2-nitrobenzene-1,3-dicarboxylic acid (m-H2 BDC-NO2 ) was employed which exclusively led to the formation of [Ga(OH)(C8 H3 NO6 )] (Ga-MIL-53-m-BDC-NO2 ), which is isoreticular to Ga-MIL-53-L2 . Density Functional Theory (DFT) calculations confirmed the higher stability of Ga-MIL-53-L2 compared to Ga-CAU-10-L2 and grand canonical Monte Carlo simulations (GCMC) are in agreement with the observed water adsorption isotherms of Ga-MIL-53-L2 .

Multivariate Sulfonic-Based Titanium Metal-Organic Frameworks as Super-protonic Conductors

The proton-conducting performances of a microporous Ti-based metal-organic framework (MOF), MIP-207, were successfully tuned using a multicomponent ligand replacement strategy to gradually introduce a controlled amount of sulfonic acid groups as a source of Brönsted acidic sites while keeping the robustness and ecofriendly synthesis conditions of the starting material. Typically, multivariate sulfonic-based solids MIP-207-(SO₃H-IPA)_x-(BTC)_1-x were prepared by combining various ratios of trimesate 1,3,5-benzenetricarboxylate (BTC) moieties and 5-SO₃H-isophthalate (SO₃H-IPA). The best sulfonic-MOF candidate that combines structural integrity with high proton conductivity values (e.g., σ = 2.6 × 10^-2 S cm^-1 at 363 K/95% relative humidity) was further investigated using ab initio molecular dynamics simulations. These calculations supported that the -SO₃H groups act as proton donors and revealed that the proton transfer mechanism results from the solvation structure of protons through the fast Zundel/hydronium interconversion along the continuous H-bonded network connecting the adsorbed water molecules.

Free Flap Reconstruction in Head and Neck Surgery: Experience in Bangabandhu Sheikh Mujib Medical University

Free flap reconstruction after surgical ablation of head & neck cancer greatly improve the surgical outcome. Microvascular anastomosis is an important part of Microsurgery and it is not widely practiced in every center. A retrospective review was conducted in the Head & Neck Division of Otolaryngology-Head & Neck Surgery Department, Bangabandhu Sheikh Mujib Medical University (BSMMU), Bangladesh from May 2016 to June 2017. Total 20 patients with head & neck cancer had been treated surgically between this period and 14 patients were reconstructed with free flap. The focus of this study is to establish the surgical outcome, which is more with free flap reconstruction in the patients previously diagnosed as head & neck cancer. We reconstructed 14 cases of oral cavity carcinoma (Stage IV) with the free flap. Majority cases were carcinoma involving the buccal mucosa with retromolar trigone (36%) followed by buccal mucosa (22%), buccal mucosa with lower alveolus (21%), carcinoma tongue with floor of the mouth (14%) and floor of the mouth (7%). Radial forearm freflap (RFFF) were commonly used in 10 cases (71.4%) and Anterolateral thigh flap (ALT) used in four cases (21.5%). Partial flap loss was seen in one case and wound infection occurred in another case but both were managed successfully with postoperative dressing and debridement. Microvascular free flap reconstruction can be a good choice after surgical removal of the head & neck cancer diseases and it should be practiced in every well-equipped tertiary medical center with the help of properly trained surgeon.

Fetomaternal Outcome of Pregnancy in Women with Tetralogy of Fallot

This prospective study was done to determine fetomaternal outcomes of pregnancy in women with Tetralogy of Fallot (TOF) and carried out in two centres especially in the care of patients with adult congenital heart disease (CHD) from January 2005 to December 2009. Clinical, haemodynamic and obstetric data were reviewed for pregnant women with TOF. Ten (10) pregnant women were identified in the age range 18 to 47 years. Most of the patients were in the age group of 18 to 27 years, 34 to 36 weeks gestational age (in week) and primi gravida (60%). Right-sided aortic arch (20%) and major anomalies of pulmonary collaterals (30%) were common anomalies anatomical association. Normal vaginal delivery was the mode of delivery (70%) in the majority of the patients. Spontaneous abortions were occurred in 3(30%) patients. Primary maternal cardiac events complicating pregnancies were congestive heart failure (20%), arrhythmias and cardiovascular events (10%). Premature labor (40%) was the most common obstetric complication. Premature birth (40%), fetal demise (20%), neonatal death (10%) and cardiac anomaly at birth (10%) were the offspring complications in the study. Women with TOF can go through pregnancy with a low risk to themselves with frequent treatable complications, but there is a high incidence of miscarriage, premature births and low birth weight. An incidence of congenital anomaly in the fetus is higher than that found in the normal population.

Hexahydroxytriphenylene for the synthesis of group 13 MOFs - a new inorganic building unit in a β-cristobalite type structure

Two new, microporous MOFs of framework composition ((CH3)2NH2)2[M3O(HHTP)(HHTP˙)], M = Al3+, Ga3+, H6HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene, are described. Electron diffraction combined with molecular simulations show that these compounds crystallize in the β-cristobalite structure, containing a new type of trinuclear inorganic building unit for MOFs and radical anions.

Total Lip Reconstruction after Excision of Cancer with Composite Radial Forearm Palmaris Longus Tendon Free Flap

Reconstruction of total lip is a challenging task for a plastic surgeon. It becomes more complicated when there is loss of additional tissues like angle of mouth, buccal mucosa or floor of the mouth. Radial forearm flap with palmaris longus tendon provides an easier but reliable technique for three dimensional lip reconstructions with good functional and aesthetic outcome. In this short observational series we included 5 patients of total lip reconstruction and conducted at Sylhet MAG Osmani Medical College Hospital and Private Clinic of Sylhet, Bangladesh from January 2014 to December 2017. Among these one was a case of basal cell carcinoma of upper lip and rest was squamous cell carcinoma of lower lip. The mean age was 71 years. All the flaps survived and patients had normal speech and oral continence. Composite radial forearm flap with palmaris longus tendon is a good, reliable option for total lip reconstruction.

A metal-organic framework for efficient water-based ultra-low-temperature-driven cooling

Efficient use of energy for cooling applications is a very important and challenging field in science. Ultra-low temperature actuated (T_driving < 80 °C) adsorption-driven chillers (ADCs) with water as the cooling agent are one environmentally benign option. The nanoscale metal-organic framework [Al(OH)(C₆H₂O₄S)] denoted CAU-23 was discovered that possess favorable properties, including water adsorption capacity of 0.37 g_H2O/g_sorbent around p/p₀ = 0.3 and cycling stability of at least 5000 cycles. Most importantly the material has a driving temperature down to 60 °C, which allows for the exploitation of yet mostly unused temperature sources and a more efficient use of energy. These exceptional properties are due to its unique crystal structure, which was unequivocally elucidated by single crystal electron diffraction. Monte Carlo simulations were performed to reveal the water adsorption mechanism at the atomic level. With its green synthesis, CAU-23 is an ideal material to realize ultra-low temperature driven ADC devices.

Correction: Modulation of the mechanical energy storage performance of the MIL-47(VIV) metal organic framework by ligand functionalization

Correction for ‘Modulation of the mechanical energy storage performance of the MIL-47(V^IV) metal organic framework by ligand functionalization’ by Pascal G. Yot et al., Dalton Trans., 2019, DOI: 10.1039/c8dt04214d.

Revisiting the water sorption isotherm of MOF using electrical measurements

Adsorption/desorption isotherms of Cr-soc-MOF-1.

Modulation of the mechanical energy storage performance of the MIL-47(VIV) metal organic framework by ligand functionalization

The functionalization of the metal-organic framework MIL-47(V^IV) with ligands bearing bulky functional groups (-Br or -CF₃) has been envisaged as a possible route to enhance the mechanical energy storage performances of this family of hybrid porous materials. This exploratory work was carried out by coupling advanced experimental techniques (mercury intrusion and X-ray powder diffraction) supported by density functional theory calculations. MIL-47(V^IV)-BDC-CF₃ was demonstrated to be one of the most promising porous materials for mechanical energy-related applications with performance in terms of work energy which surpasses that of any porous solids reported so far.

A phase transformable ultrastable titanium-carboxylate framework for photoconduction

Porous titanium oxide materials are attractive for energy-related applications. However, many suffer from poor stability and crystallinity. Here we present a robust nanoporous metal-organic framework (MOF), comprising a Ti₁₂O₁₅ oxocluster and a tetracarboxylate ligand, achieved through a scalable synthesis. This material undergoes an unusual irreversible thermally induced phase transformation that generates a highly crystalline porous product with an infinite inorganic moiety of a very high condensation degree. Preliminary photophysical experiments indicate that the product after phase transformation exhibits photoconductive behavior, highlighting the impact of inorganic unit dimensionality on the alteration of physical properties. Introduction of a conductive polymer into its pores leads to a significant increase of the charge separation lifetime under irradiation. Additionally, the inorganic unit of this Ti-MOF can be easily modified via doping with other metal elements. The combined advantages of this compound make it a promising functional scaffold for practical applications.

Computational structure determination of novel metal–organic frameworks

A structure prediction tool has been developed to guide the discovery of MOF materials.

Outcome of Endoscopic Sinus Surgery in the Treatment of Chronic Rhinosinusitis

This prospective study was conducted to compare the outcome of endoscopic sinus surgery (ESS) using SNOT-20 score chart (subjective) and Lund & Kennedy scoring chart (objective) and carried out in the Department of Otolaryngology & Head-Neck Surgery, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Dhaka Medical College Hospital (DMCH) & Shaheed Suhrawardy Medical College Hospital (ShSMCH) from July 2010 to March 2012. Total 73 admitted cases were selected purposively for ESS, male 53(72.60%) and female 20(27.40%). Among the study participants 10(13.7%) had chronic rhinosinusitis with bilateral polyposis and 26(35.62%) had chronic rhinosinusitis with unilateral polyposis and 12(16.44%) had bilateral chronic rhinosinusitis without polyposis and 25(34.25%) had unilateral chronic rhinosinusitis without polyposis. Surgical procedures done among the patients were Uncinectomy (infundibulectomy), Middle Meatal Antrostomy; Anterior Ethmoidectomy; Sphenoidotomy, Associated septoplasty and no significant per or post operative complications were noted. In Chronic rhinosinusitis (CRS) with polyposis pre operative SNOT-20 mean and SD 1.322±0.341 and post ESS snot-20 mean and SD 0.3472±0.0755, CRS without polyposis pre operative SNOT-20 mean and SD 0.9297±0.86 and post ESS SNOT-20 mean and SD 1986±0.0558. In CRS with polyposis pre operative Lund & Kennedy score of endoscopic assessment, mean and SD 5.333±2.255 and post ESS mean and SD 1.31±1.009. In CRS without polyposis pre op Lund & Kennedy score mean and SD 3.108±1.074 and post ESS mean and SD 0.76±0.641.Post ESS SNOT-20 in CRS with Polyposis, 't' test result was 27.58 which was significant (p<0.001) and in CRS without Polyposis was 21.622 which was significant (p<0.001); Lund & Kennedy Score of post ESS in CRS with Polyposis 't' test result was 7.763 which was significant (p<0.001), CRS without Polyposis was 7.177 which was significant (p<0.001).This implies that outcome of ESS in treatment of CRS with or without polyposis had statistically significant role. Symptomatic relief and quality of life improvement after ESS was compared by improvement in post operative scores of SNOT-20 & Lund-Kennedy score of endoscopic assessment. Post operative lower values were considered to be better improvement status. The results of the study suggests that ESS performed in Chronic Rhinosinusitis without Polyposis cases, relief of symptoms and quality of life improved was better than Chronic Rhinosinusitis with Polyposis cases postoperatively as compared by SNOT-20 and Lund & Kennedy score of endoscopic assessment.

Overexpression of sonic hedgehog in the triple negative breast cancer: clinicopathological characteristics of high burden breast cancer patients from Bangladesh

Dysregulation of Hedgehog (Hh) signaling pathway has been documented in mammary gland development and breast cancer (BC) progression. Despite the remarkable progress in therapeutic interventions, BC related mortality in Bangladesh increased in the last decade. Triple negative breast cancer (TNBC) still presents a critical therapeutic challenge. Thus effective targeted therapy is urgently needed. In this study, we report the clinicopathological characteristics and prognosis of BC patients from Bangladesh. Routine immunohistochemical analysis and high throughput RNA-Seq data from the TCGA library were used to analyze the expression pattern and association of high and low level of Shh expression in a collection of BC patients with a long-term follow-up. High levels of Shh were observed in a subset of BC tumors with poor prognostic pathological features. Higher level of Shh expression correlated with a significantly poorer overall survival of patients compared with patients whose tumors expressed a low level of Shh. These data support the contention that Shh could be a novel biomarker for breast cancer that is involved in mediating the aggressive phenotype of BC. We propose that BC patients exhibiting a higher level of Shh expression, representing a subset of BC patients, would be amenable to Shh targeted therapy.

Hydrogen adsorption in metal-organic frameworks: the role of nuclear quantum effects

The role of nuclear quantum effects on the adsorption of molecular hydrogen in metal-organic frameworks (MOFs) has been investigated on grounds of Grand-Canonical Quantized Liquid Density-Functional Theory (GC-QLDFT) calculations. For this purpose, we have carefully validated classical H2-host interaction potentials that are obtained by fitting Born-Oppenheimer ab initio reference data. The hydrogen adsorption has first been assessed classically using Liquid Density-Functional Theory and the Grand-Canonical Monte Carlo methods. The results have been compared against the semi-classical treatment of quantum effects by applying the Feynman-Hibbs correction to the Born-Oppenheimer-derived potentials, and by explicit treatment within the GC-QLDFT. The results are compared with experimental data and indicate pronounced quantum and possibly many-particle effects. After validation calculations have been carried out for IRMOF-1 (MOF-5), GC-QLDFT is applied to study the adsorption of H2 in a series of MOFs, including IRMOF-4, -6, -8, -9, -10, -12, -14, -16, -18, and MOF-177. Finally, we discuss the evolution of the H2 quantum fluid with increasing pressure and lowering temperature.

Pylorus Preserving Pancreaticoduodenectomy vs. Standard Whipple's Procedure in Case of Carcinoma head of the Pancreas and Periampullary Carcinoma

Pancreatic carcinoma is a life threatening condition. Surgical resection is the only hope of cure. Advances in surgical technique have reduced the mortality rate. Nevertheless, operative complications related with morbidity still remains high. Two operation techniques in the treatment of periampullary and pancreatic head cancer: the Standard Whipple operation (SW) and Pylorus Preserving Pancreaticoduodenectomy (PPPD) are performed predominantly. This study was performed to compare the results of Pylorus Preserving Pancreaticoduodenectomy (PPPD) with that of the Standard Whipple's (SW) procedure. This prospective study was carried out in the Department of General Surgery, BSMMU in two years duration. All admitted patient's with periampullary carcinoma and carcinoma of the head of the pancreas were included and randomized for a SW or a PPPD resection. Data regarding patients demographics, preoperative assessment, intraoperative and postoperative findings were collected and analyzed. Less blood loss (2.67±0.65 units in Group I and 2.88±0.64 units in Group II), fewer need of blood transfusions and shorter hospital stay in the PPPD group were observed. Gastrointestinal leakage was similar in both groups of patients (1:1). One pancreatic fistula (8.3% in Group I) was observed in PPPD group and one intra-abdominal abscess developed in Standard Whipple's procedure (00.0% in Group I and 12.5% in Group II). Bile leakage was higher in standard Whipple procedure (8.3% in Group I and 37.5% in Group II). Morbidity was more or less similar in both groups (58.0% in Group I and 50.0% in Group II) but one patient (12.5% in Group II) died in standard Whipple's resection. PPPD procedure is more effective treatment for periampullary carcinoma and cancer of the pancreatic head region than the standard Whipple's operation.

MHD boundary layer radiative, heat generating and chemical reacting flow past a wedge moving in a nanofluid

The present study analyzed numerically magneto-hydrodynamics (MHD) laminar boundary layer flow past a wedge with the influence of thermal radiation, heat generation and chemical reaction. This model used for the momentum, temperature and concentration fields. The principal governing equations is based on the velocity u_w (x) in a nanofluid and with a parallel free stream velocity u_e (x) and surface temperature and concentration. Similarity transformations are used to transform the governing nonlinear boundary layer equations for momentum, thermal energy and concentration to a system of nonlinear ordinary coupled differential equations with fitting boundary conditions. The transmuted model is shown to be controlled by a number of thermo-physical parameters, viz. the magnetic parameter, thermal convective parameter, mass convective parameter, radiation-conduction parameter, heat generation parameter, Prandtl number, Lewis number, Brownian motion parameter, thermophoresis parameter, chemical reaction parameter and pressure gradient parameter. Numerical elucidations are obtained with the legendary Nactsheim-Swigert shooting technique together with Runge-Kutta six order iteration schemes. Comparisons with previously published work are accomplished and proven an excellent agreement.

Serum lipid profile and its association with hypertension in Bangladesh

Background

Hypertension and dyslipidemia are major risk factors for cardiovascular disease, accounting for the highest morbidity and mortality among the Bangladeshi population. The objective of this study was to determine the association between serum lipid profiles in hypertensive patients with normotensive control subjects in Bangladesh.

Methods

A cross-sectional study was carried out among 234 participants including 159 hypertensive patients and 75 normotensive controls from January to December 2012 in the National Centre for Control of Rheumatic Fever and Heart Disease in Dhaka, Bangladesh. Data were collected on sociodemographic factors, anthropometric measurements, blood pressure, and lipid profile including total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL), and high density lipoprotein (HDL).

Results

The mean (± standard deviation) systolic blood pressure and diastolic blood pressure of the participants were 137.94±9.58 and 94.42±8.81, respectively, which were higher in the hypertensive patients (P<0.001). The serum levels of TC, TG, and LDL were higher while HDL levels were lower in hypertensive subjects compared to normotensives, which was statistically significant (P<0.001). Age, waist circumference, and body mass index showed significant association with hypertensive patients (P<0.001) but not with normotensives. The logistic regression analysis showed that hypertensive patients had 1.1 times higher TC and TG, 1.2 times higher LDL, and 1.1 times lower HDL than normotensives, which was statistically significant (P<0.05).

Conclusion

Hypertensive patients in Bangladesh have a close association with dyslipidemia and need measurement of blood pressure and lipid profile at regular intervals to prevent cardiovascular disease, stroke, and other comorbidities.

Major Salivary Gland Tumors: A Clinicopathological Study

Background: Major salivary gland tumors comprise a morphologically diverse group of rare tumors. The tumors also have variations in their clinicopathological profile related to racial and geographic differences. Objective: To find out the frequency of different types of major salivary gland neoplasm. Methodology: This cross sectional study was carried out on 50 patients having major salivary gland tumor in the departments of Otolaryngology of Bangabandhu Sheikh Mujib Medical University, Dhaka Medical College Hospital and Sir Salimullah Medical College Hospital from January 2010 to September 2010. Result: In this study, most cases occur in 5th decade. Incidence of malignant and benign parotid neoplasm was found 23.8% and 76.2% respectively. Benign and malignant tumors of submandibular gland were 50% in each group. No sublingual gland neoplasm was found in this group. Conclusion: Parotid gland was the most common site of origin of both benign and malignant tumours. Plemorphic adenoma was the most common benign salivary gland tumour and mucoepidermoid carcinoma was the most frequent malignant neoplasm. DOI: http://dx.doi.org/10.3329/jssmc.v5i1.16250 J Shaheed Suhrawardy Med Coll, 2013;5(1):43-45